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23 Sep 2020 at 01:52
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Bibliography on: Endosymbiosis


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RJR: Recommended Bibliography 23 Sep 2020 at 01:52 Created: 


A symbiotic relationship in which one of the partners lives within the other, especially if it lives within the cells of the other, is known as endosymbiosis. Mitochondria, chloroplasts, and perhaps other cellular organelles are believed to have originated from a form of endosymbiosis. The endosymbiotic origin of eukaryotes seems to have been a biological singularity — that is, it happened once, and only once, in the history of life on Earth.

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Citations The Papers (from PubMed®)


RevDate: 2020-09-21

Ip JC, Xu T, Sun J, et al (2020)

Host-Endosymbiont Genome Integration in a Deep-Sea Chemosymbiotic Clam.

Molecular biology and evolution pii:5909661 [Epub ahead of print].

Endosymbiosis with chemosynthetic bacteria has enabled many deep-sea invertebrates to thrive at hydrothermal vents and cold seeps, but most previous studies on this mutualism have focused on the bacteria only. Vesicomyid clams dominate global deep-sea chemosynthesis-based ecosystems. They differ from most deep-sea symbiotic animals in passing their symbionts from parent to offspring, enabling intricate co-evolution between the host and the symbiont. Here, we sequenced the genomes of the clam Archivesica marissinica (Bivalvia: Vesicomyidae) and its bacterial symbiont to understand the genomic/metabolic integration behind this symbiosis. At 1.52 gigabases, the clam genome encodes 28 genes horizontally transferred from bacteria, a large number of pseudogenes and transposable elements whose massive expansion corresponded to the timing of the rise and subsequent divergence of symbiont-bearing vesicomyids. The genome exhibits gene family expansion in cellular processes that likely facilitate chemoautotrophy, including gas delivery to support energy and carbon production, metabolite exchange with the symbiont, and regulation of the bacteriocyte population. Contraction in cellulase genes is likely adaptive to the shift from phytoplankton-derived to bacteria-based food. It also shows contraction in bacterial recognition gene familie, indicative of suppressed immune response to the endosymbiont. The gammaproteobacterium endosymbiont has a reduced genome of 1.03 megabases but retains complete pathways for sulfur oxidation, carbon fixation, and biosynthesis of 20 common amino acids, indicating the host's high dependence on the symbiont for nutrition. Overall, the host-symbiont genomes show not only tight metabolic complementarity, but also distinct signatures of co-evolution allowing the vesicomyids to thrive in chemosynthesis-based ecosystems.

RevDate: 2020-09-18

Becker DM, NJ Silbiger (2020)

Nutrient and sediment loading affect multiple facets of coral functionality in a tropical branching coral.

The Journal of experimental biology pii:jeb.225045 [Epub ahead of print].

Coral reefs, one of the most diverse ecosystems in the world, face increasing pressures from global and local anthropogenic stressors. Therefore, a better understanding of the ecological ramifications of warming and land-based inputs (e.g., sedimentation and nutrient loading) on coral reef ecosystems is necessary. In this study, we measured how a natural nutrient and sedimentation gradient affected multiple facets of coral functionality, including endosymbiont and coral host response variables, holobiont metabolic responses, and percent cover of Pocillopora acuta colonies in Mo'orea, French Polynesia. We used thermal performance curves to quantify the relationship between metabolic rates and temperature along the environmental gradient. We found that algal endosymbiont % nitrogen content, endosymbiont densities, and total chlorophyll a content increased with nutrient input, while endosymbiont nitrogen content cell-1 decreased, likely representing competition among the algal endosymbionts. Nutrient and sediment loading decreased coral metabolic responses to thermal stress in terms of their thermal performance and metabolic rate processes. The acute thermal optimum for dark respiration decreased, along with the maximal performance for gross photosynthetic and calcification rates. Gross photosynthetic and calcification rates normalized to a reference temperature (26.8 °C) decreased along the gradient. Lastly, percent cover of P. acuta colonies decreased by nearly two orders of magnitude along the nutrient gradient. These findings illustrate that nutrient and sediment loading affect multiple levels of coral functionality. Understanding how local-scale anthropogenic stressors influence the responses of corals to temperature can inform coral reef management, particularly on the mediation of land-based inputs into coastal coral reef ecosystems.

RevDate: 2020-09-16
CmpDate: 2020-09-16

Kakumanu ML, DeVries ZC, Barbarin AM, et al (2020)

Bed bugs shape the indoor microbial community composition of infested homes.

The Science of the total environment, 743:140704.

Indoor pests, and the allergens they produce, adversely affect human health. Surprisingly, however, their effects on indoor microbial communities have not been assessed. Bed bug (Cimex lectularius) infestations pose severe challenges in elderly and low-income housing. They void large amounts of liquid feces into the home environment, which might alter the indoor microbial community composition. In this study, using bed bug-infested and uninfested homes, we showed a strong impact of bed bug infestations on the indoor microbial diversity. Floor dust samples were collected from uninfested and bed bug-infested homes and their microbiomes were analyzed before and after heat interventions that eliminated bed bugs. The microbial communities of bed bug-infested homes were radically different from those of uninfested homes, and the bed bug endosymbiont Wolbachia was the major driver of this difference. After bed bugs were eliminated, the microbial community gradually shifted toward the community composition of uninfested homes, strongly implicating bed bugs in shaping the dust-associated environmental microbiome. Further studies are needed to understand the viability of these microbial communities and the potential risks that bed bug-associated microbes and their metabolites pose to human health.

RevDate: 2020-09-14

Gonçalves WG, Fernandes KM, Silva APA, et al (2020)

Ultrastructure of the Bacteriocytes in the Midgut of the Carpenter ant Camponotus rufipes: Endosymbiont Control by Autophagy.

Microscopy and microanalysis : the official journal of Microscopy Society of America, Microbeam Analysis Society, Microscopical Society of Canada pii:S1431927620024484 [Epub ahead of print].

The carpenter ant Camponotus rufipes has intracellular bacteria in bacteriocytes scattered in the midgut epithelium, which have different amounts of endosymbionts, according to the developmental stages. However, there are no detailed data about the midgut cells in adult workers. The present work aimed to evaluate the morphology and cellular events that coordinate the abundance of endosymbionts in the midgut cells in C. rufipes workers. The midgut epithelium has digestive cells, bacteriocytes, and cells with intermediate morphology. The latter is similar to bacteriocytes, due to the abundance of endosymbionts, and similar to digestive cells, due to their microvilli. The digestive and intermediate cells are rich in autophagosomes and autolysosomes, both with bacteria debris in the lumen. These findings suggest that midgut cells of C. rufipes control the endosymbiont level by the autophagy pathway.

RevDate: 2020-09-10

Rossbacher S, C Vorburger (2020)

Prior adaptation of parasitoids improves biological control of symbiont-protected pests.

Evolutionary applications, 13(8):1868-1876 pii:EVA12934.

There is increasing demand for sustainable pest management to reduce harmful effects of pesticides on the environment and human health. For pest aphids, biological control with parasitoid wasps provides a welcome alternative, particularly in greenhouses. However, aphids are frequently infected with the heritable bacterial endosymbiont Hamiltonella defensa, which increases resistance to parasitoids and thereby hampers biological control. Using the black bean aphid (Aphis fabae) and its main parasitoid Lysiphlebus fabarum, we tested whether prior adaptation of parasitoids can improve the control of symbiont-protected pests. We had parasitoid lines adapted to two different strains of H. defensa by experimental evolution, as well as parasitoids evolved on H. defensa-free aphids. We compared their ability to control caged aphid populations comprising 60% unprotected and 40% H. defensa-protected aphids, with both H. defensa strains present in the populations. Parasitoids that were not adapted to H. defensa had virtually no effect on aphid population dynamics compared to parasitoid-free controls, but one of the adapted lines and a mixture of both adapted lines controlled aphids successfully, strongly benefitting plant growth. Selection by parasitoids altered aphid population composition in a very specific manner. Aphid populations became dominated by H. defensa-protected aphids in the presence of parasitoids, and each adapted parasitoid line selected for the H. defensa strain it was not adapted to. This study shows, for the first time, that prior adaptation of parasitoids improves biological control of symbiont-protected pests, but the high specificity of parasitoid counter-resistance may represent a challenge for its implementation.

RevDate: 2020-09-10

Jain SS, Afiq-Rosli L, Feldman B, et al (2020)

Homogenization of Endosymbiont Communities Hosted by Equatorial Corals during the 2016 Mass Bleaching Event.

Microorganisms, 8(9): pii:microorganisms8091370.

Thermal stress drives the bleaching of reef corals, during which the endosymbiotic relationship between Symbiodiniaceae microalgae and the host breaks down. The endosymbiont communities are known to shift in response to environmental disturbances, but how they respond within and between colonies during and following bleaching events remains unclear. In 2016, a major global-scale bleaching event hit countless tropical reefs. Here, we investigate the relative abundances of Cladocopium LaJeunesse & H.J.Jeong, 2018 and Durusdinium LaJeunesse, 2018 within and among Pachyseris speciosa colonies in equatorial Singapore that are known to host both these Symbiodiniaceae clades. Bleached and unbleached tissues from bleaching colonies, as well as healthy colonies, during and following the bleaching event were sampled and analyzed for comparison. The nuclear ribosomal internal transcribed spacer (ITS) regions were separately amplified and quantified using a SYBR Green-based quantitative polymerase chain reaction (qPCR) method and Illumina high-throughput sequencing. We found Cladocopium to be highly abundant relative to Durusdinium. The relative abundance of Durusdinium, known to be thermally tolerant, was highest in post-bleaching healthy colonies, while bleached and unbleached tissues from bleaching colonies as well as tissue from healthy colonies during the event had depressed proportions of Durusdinium. Given the importance of Durusdinium for thermal tolerance and stress response, it is surprising that bleached tissue showed limited change over healthy tissue during the bleaching event. Moreover, colonies were invariably dominated by Cladocopium during bleaching, but a minority of colonies were Durusdinium-dominant during non-bleaching times. The detailed characterization of Symbiodiniaceae in specific colonies during stress and recovery will provide insights into this crucial symbiosis, with implications for their responses during major bleaching events.

RevDate: 2020-09-09

Ciuca L, Vismarra A, Lebon W, et al (2020)

New insights into the biology, diagnosis and immune response to Dirofilaria repens in the canine host.

Veterinary parasitology: X, 4:100029 pii:100029.

Dogs are the primary host for Dirofilaria repens, therefore it is mandatory to accurately diagnose the canine infection and to expand our current knowledge on parasite biology and the immune response of the infected host for a better prevention.Thus, the aim of the present study was to provide new insights from experimental infections of dogs with D. repens, focusing on the evaluation of: 1) the pre-patent period and 2) the antibody response against D. repens somatic antigens and against the Wolbachia endosymbiont. Briefly, on Day 0, twenty purpose-bred Beagle dogs were experimentally infected with 50 infective larvae (L3) of D. repens. Starting from Day 58 until the last day of the study (Day 281), blood samples were collected on a monthly basis for detection of antibodies against D. repens (Dr) and recombinant Wolbachia surface protein (rWSP) by non-commercial IgG-ELISAs. Additional samples were collected on Days 220, 245 and 281 for the detection of microfilariae (mff) using the modified Knott's test and biomolecular analysis, following two PCR protocols: Gioia et al. (2010; protocol A) and Rishniw et al. (2006- protocol B). The results were analysed by univariate statistical analyses using 2 × 2 contingency tables and K Cohen was calculated to assess the agreement among all the diagnostic techniques. Overall, the outcome of the study revealed that out of the 20 dogs experimentally infected with D. repens, 16 (80 %) were microfilaraemic, 17 (85 %) were positive at DNA detection in the blood, 18 (90 %) had D. repens antibodies and 16 (80 %) had Wolbachia antibodies on the last day of the study. The overall k agreement between Knott's and PCR protocol B was 0.442 (P = 0.0001) and increased throughout the study, reaching 0.828 (P = 0.0001) on Day 281. To the authors knowledge, this is only the second study reporting antibody response to D. repens somatic antigen in experimentally infected dogs. ELISA results showed that an antibody response develops before the onset of patency, and steadily increases with time. Results would suggest that the development of an immunological response to infection could lead to application in epidemiological studies, risk assessment and as an aid in the diagnostic approach in dogs, in particular for early infections without mff.

RevDate: 2020-09-07

Lenhart PA, JA White (2020)

Endosymbionts facilitate rapid evolution in a polyphagous herbivore.

Journal of evolutionary biology [Epub ahead of print].

Maternally transmitted bacterial symbionts can be important mediators of the interactions between insect herbivores and their foodplants. These symbionts are often facultative (present in some host individuals but not others) and can have large effects on their host's phenotype, thus giving rise to heritable variation upon which selection can act. In the cowpea aphid (Aphis craccivora) it has been established that the facultative endosymbiont Arsenophonus improves aphid performance on black locust trees (Robinia pseudoacacia) but not on fava (Vicia faba). Here, we tested whether this fitness differential translated into contemporaneous evolution of aphid populations associated with the different plants. In a laboratory study lasting 16 weeks, we found that the frequency of Arsenophonus-infected individuals significantly increased over time for aphid populations on black locust but declined for aphid populations on fava. By the end of the experiment, Arsenophonus infection was >3× more common on black locust than fava, which is comparable to previously described infection frequencies in natural field populations. Our results clearly demonstrate that aphid populations with mixed facultative symbiont infection status can rapidly evolve in response to the selective environments imposed by different host plants. This selection differential may be a sufficient explanation for the global association between Arsenophonus-infected cowpea aphids and black locust trees, without invoking additional assortative mechanisms. Because the aphid and plant originate from different parts of the world, we further hypothesize that Arsenophonus infection may have acted as a preadaptation that has promoted functional specialisation of infected aphids on a novel host plant.

RevDate: 2020-09-03

Karakaidos P, T Rampias (2020)

Mitonuclear Interactions in the Maintenance of Mitochondrial Integrity.

Life (Basel, Switzerland), 10(9): pii:life10090173.

In eukaryotic cells, mitochondria originated in an α-proteobacterial endosymbiont. Although these organelles harbor their own genome, the large majority of genes, originally encoded in the endosymbiont, were either lost or transferred to the nucleus. As a consequence, mitochondria have become semi-autonomous and most of their processes require the import of nuclear-encoded components to be functional. Therefore, the mitochondrial-specific translation has evolved to be coordinated by mitonuclear interactions to respond to the energetic demands of the cell, acquiring unique and mosaic features. However, mitochondrial-DNA-encoded genes are essential for the assembly of the respiratory chain complexes. Impaired mitochondrial function due to oxidative damage and mutations has been associated with numerous human pathologies, the aging process, and cancer. In this review, we highlight the unique features of mitochondrial protein synthesis and provide a comprehensive insight into the mitonuclear crosstalk and its co-evolution, as well as the vulnerabilities of the animal mitochondrial genome.

RevDate: 2020-09-02

Guo Y, Takashima Y, Sato Y, et al (2020)

Mycoavidus sp. Strain B2-EB: Comparative Genomics Reveals Minimal Genomic Features Required by a Cultivable Burkholderiaceae-Related Endofungal Bacterium.

Applied and environmental microbiology, 86(18): pii:AEM.01018-20.

Obligate bacterial endosymbionts are critical to the existence of many eukaryotes. Such endobacteria are usually characterized by reduced genomes and metabolic dependence on the host, which may cause difficulty in isolating them in pure cultures. Family Burkholderiaceae-related endofungal bacteria affiliated with the Mycoavidus-Glomeribacter clade can be associated with the fungal subphyla Mortierellomycotina and Glomeromycotina. In this study, a cultivable endosymbiotic bacterium, Mycoavidus sp. strain B2-EB, present in the fungal host Mortierella parvispora was obtained successfully. The B2-EB genome (1.88 Mb) represents the smallest genome among the endofungal bacterium Mycoavidus cysteinexigens (2.64-2.80 Mb) of Mortierella elongata and the uncultured endosymbiont "Candidatus Glomeribacter gigasporarum" (1.37 to 2.36 Mb) of arbuscular mycorrhizal fungi. Despite a reduction in genome size, strain B2-EB displays a high genome completeness, suggesting a nondegenerative reduction in the B2-EB genome. Compared with a large proportion of transposable elements (TEs) in other known Mycoavidus genomes (7.2 to 11.5% of the total genome length), TEs accounted for only 2.4% of the B2-EB genome. This pattern, together with a high proportion of single-copy genes in the B2-EB genome, suggests that the B2-EB genome reached a state of relative evolutionary stability. These results represent the most streamlined structure among the cultivable endofungal bacteria and suggest the minimal genome features required by both an endofungal lifestyle and artificial culture. This study allows us to understand the genome evolution of Burkholderiaceae-related endosymbionts and to elucidate microbiological interactions.IMPORTANCE This study attempted the isolation of a novel endobacterium, Mycoavidus sp. B2-EB (JCM 33615), harbored in the fungal host Mortierella parvispora E1425 (JCM 39028). We report the complete genome sequence of this strain, which possesses a reduced genome size with relatively high genome completeness and a streamlined genome structure. The information indicates the minimal genomic features required by both the endofungal lifestyle and artificial cultivation, which furthers our understanding of genome reduction in fungal endosymbionts and extends the culture resources for biotechnological development on engineering synthetic microbiomes.

RevDate: 2020-08-29

Li L, Wang M, Li L, et al (2020)

Endosymbionts of vent-dwelling metazoans in PACManus-diversity and potential adaptive features revealed by genome analysis.

Applied and environmental microbiology pii:AEM.00815-20 [Epub ahead of print].

Deep-sea hydrothermal vent communities are dominated by invertebrates, namely bathymodiolin mussels, siboglinid tubeworms, and provannid snails. Symbiosis is considered key to successful colonization by these sedentary species in such extreme environments. In the PACManus vent fields, snails, tubeworms, and mussels each colonized a niche with distinct geochemical characteristics. To better understand the metabolic potentials and genomic features contributing to host-environment adaptation, we compared genomes of the symbionts of Bathymodiolus manusensis, Arcovestia ivanovi, and Alviniconcha boucheti sampled at PACManus and discuss their environmental adaptive features. We found that B. manusensis and A. ivanovi are colonized by γ-proteobacteria from distinct clades, whereas endosymbionts of B. manusensis feature high intraspecific heterogeneity with differing metabolic potentials. A. boucheti harbored three novel ϵ-proteobacteria symbionts, suggesting potential species-level diversity of snail symbionts . Genome comparisons revealed gene families related to low pH homeostasis, metal resistance, oxidative stress resistance, environmental sensing/responses, and chemotaxis and motility were most abundant in A. ivanovi's symbiont, followed by symbionts of the vent-mouth-dwelling snail A. boucheti, and relatively low in the vent-periphery-dwelling mussel B. manusensis, which is consistent with their environmental adaptation and host-symbiont interactions. Gene families classified to host interaction/attachment, virulence factors/toxins, and eukaryotic-like proteins were most abundant in symbionts of mussels and least abundant in those of snails, indicating these symbionts may differ in their host-colonization strategy. Comparison of ϵ-symbionts to non-symbionts demonstrated the expanded gene families in symbionts were related to VB12 synthesis, toxin-antitoxin, methylation, and lipopolysaccharide biosynthesis, suggesting these are vital to symbiotic establishment and development in ϵ-proteobacteriaImportance Deep-sea hydrothermal vents are dominated by several invertebrate species. The establishment of symbiosis has long been thought to be the key to successful colonization by these sedentary species in such harsh environments. Yet the relationships between symbiotic bacteria and their hosts, and their role in environment adaptations generally remain unclear. In this paper, we show that the distribution of three host species showed characteristic niche partitioning in the Manus Basin, giving us opportunity to understand how they adapt to their particular habitats. This study also revealed three novel genomes of symbionts from the snails of A. boucheti Combined with a dataset of other ectosymbiont and free-living bacteria, genome comparisons of the snail endosymbionts pointed to several genetic traits that may have contributed to the lifestyle shift into the epithelial cells in ϵ-proteobacteria These findings could increase our understanding of invertebrate-endosymbiont in deep-sea ecosystems.

RevDate: 2020-08-27

Lu P, Sun Q, Fu P, et al (2020)

Wolbachia Inhibits Binding of Dengue and Zika Viruses to Mosquito Cells.

Frontiers in microbiology, 11:1750.

As traditional approaches to the control of dengue and Zika are insufficient, significant efforts have been made to develop utilization of the endosymbiotic bacterium Wolbachia to reduce the ability of mosquitoes to transmit pathogens. Although Wolbachia is known to inhibit flaviviruses in mosquitoes, including dengue virus (DENV) and Zika virus (ZIKV), it remains unclear how the endosymbiont interferes with viral replication cycle. In this study, we have carried out viral binding assays to investigate the impact of the Wolbachia strain wAlbB on the attachment of DENV serotype 2 (DENV-2) and ZIKV to Aedes aegypti Aag-2 cells. RNA interference (RNAi) was used to silence a variety of putative mosquito receptors of DENV that were differentially regulated by wAlbB in Aag-2 cells, in order to identify host factors involved in the inhibition of viral binding. Our results showed that, in addition to suppression of viral replication, Wolbachia strongly inhibited binding of both DENV-2 and ZIKV to Aag-2 cells. Moreover, the expression of two putative mosquito DENV receptors - dystroglycan and tubulin - was downregulated by wAlbB, and their knock-down resulted in the inhibition of DENV-2 binding to Aag-2 cells. These results will aid in understanding the Wolbachia-DENV interactions in mosquito and the development of novel control strategies for mosquito-borne diseases.

RevDate: 2020-08-25

Russell SL, Pepper-Tunick E, Svedberg J, et al (2020)

Horizontal transmission and recombination maintain forever young bacterial symbiont genomes.

PLoS genetics, 16(8):e1008935 pii:PGENETICS-D-19-01871 [Epub ahead of print].

Bacterial symbionts bring a wealth of functions to the associations they participate in, but by doing so, they endanger the genes and genomes underlying these abilities. When bacterial symbionts become obligately associated with their hosts, their genomes are thought to decay towards an organelle-like fate due to decreased homologous recombination and inefficient selection. However, numerous associations exist that counter these expectations, especially in marine environments, possibly due to ongoing horizontal gene flow. Despite extensive theoretical treatment, no empirical study thus far has connected these underlying population genetic processes with long-term evolutionary outcomes. By sampling marine chemosynthetic bacterial-bivalve endosymbioses that range from primarily vertical to strictly horizontal transmission, we tested this canonical theory. We found that transmission mode strongly predicts homologous recombination rates, and that exceedingly low recombination rates are associated with moderate genome degradation in the marine symbionts with nearly strict vertical transmission. Nonetheless, even the most degraded marine endosymbiont genomes are occasionally horizontally transmitted and are much larger than their terrestrial insect symbiont counterparts. Therefore, horizontal transmission and recombination enable efficient natural selection to maintain intermediate symbiont genome sizes and substantial functional genetic variation.

RevDate: 2020-08-24

Wada N, Yuasa H, Kajitani R, et al (2020)

A ubiquitous subcuticular bacterial symbiont of a coral predator, the crown-of-thorns starfish, in the Indo-Pacific.

Microbiome, 8(1):123 pii:10.1186/s40168-020-00880-3.

BACKGROUND: Population outbreaks of the crown-of-thorns starfish (Acanthaster planci sensu lato; COTS), a primary predator of reef-building corals in the Indo-Pacific Ocean, are a major threat to coral reefs. While biological and ecological knowledge of COTS has been accumulating since the 1960s, little is known about its associated bacteria. The aim of this study was to provide fundamental information on the dominant COTS-associated bacteria through a multifaceted molecular approach.

METHODS: A total of 205 COTS individuals from 17 locations throughout the Indo-Pacific Ocean were examined for the presence of COTS-associated bacteria. We conducted 16S rRNA metabarcoding of COTS to determine the bacterial profiles of different parts of the body and generated a full-length 16S rRNA gene sequence from a single dominant bacterium, which we designated COTS27. We performed phylogenetic analysis to determine the taxonomy, screening of COTS27 across the Indo-Pacific, FISH to visualize it within the COTS tissues, and reconstruction of the bacterial genome from the hologenome sequence data.

RESULTS: We discovered that a single bacterium exists at high densities in the subcuticular space in COTS forming a biofilm-like structure between the cuticle and the epidermis. COTS27 belongs to a clade that presumably represents a distinct order (so-called marine spirochetes) in the phylum Spirochaetes and is universally present in COTS throughout the Indo-Pacific Ocean. The reconstructed genome of COTS27 includes some genetic traits that are probably linked to adaptation to marine environments and evolution as an extracellular endosymbiont in subcuticular spaces.

CONCLUSIONS: COTS27 can be found in three allopatric COTS species, ranging from the northern Red Sea to the Pacific, implying that the symbiotic relationship arose before the speciation events (approximately 2 million years ago). The universal association of COTS27 with COTS and nearly mono-specific association at least with the Indo-Pacific COTS provides a useful model system for studying symbiont-host interactions in marine invertebrates and may have applications for coral reef conservation. Video Abstract.

RevDate: 2020-08-18

Cotes-Perdomo AP, Oviedo Á, LR Castro (2020)

Molecular detection of pathogens in ticks associated with domestic animals from the Colombian Caribbean region.

Experimental & applied acarology pii:10.1007/s10493-020-00531-0 [Epub ahead of print].

Tick-borne diseases constitute a problem for livestock and public health. Given the socio-economic and environmental conditions of the Colombian Caribbean, ticks are particularly abundant, in turn exposing domestic animals and people in contact with them to such diseases. This study evaluates the presence of Babesia spp., Anaplasma spp., Coxiella spp. and Borrelia spp. in domestic animal ticks (Amblyomma mixtum, A. dissimile, Dermacentor nitens, Rhipicephalus sanguineus and R. microplus) by conventional PCR. Findings show a prevalence of 12.5% of Babesia, 0% of Borrelia, 39.4% of Anaplasma and 52.9% of Coxiella, whereas 6.2% of a total sample of 104 tick pools presented coinfections between Babesia and Anaplasma. Among the molecularly identified species are Ba. vogeli, Ba. bigemina and A. marginale, in addition to two Coxiella species-one being C. mudrowiae and the other similar to an undescribed endosymbiont of Rhipicephalus sp. It is necessary to evaluate the vector capacity of ticks such as A. mixtum, D. nitens and R. sanguineus in the transmission of A. marginale. Moreover, it is necessary to explore the role that bacteria of the genus Coxiella might have both in the health of humans and animals, and in the metabolism and reproduction of ticks. This is the first report on Babesia vogeli and B. bigemina in ticks from the Colombian Caribbean, representing a risk to animal and human health.

RevDate: 2020-08-18

Poquita-Du RC, Goh YL, Huang D, et al (2020)

Gene Expression and Photophysiological Changes in Pocillopora acuta Coral Holobiont Following Heat Stress and Recovery.

Microorganisms, 8(8): pii:microorganisms8081227.

The ability of corals to withstand changes in their surroundings is a critical survival mechanism for coping with environmental stress. While many studies have examined responses of the coral holobiont to stressful conditions, its capacity to reverse responses and recover when the stressor is removed is not well-understood. In this study, we investigated among-colony responses of Pocillopora acuta from two sites with differing distance to the mainland (Kusu (closer to the mainland) and Raffles Lighthouse (further from the mainland)) to heat stress through differential expression analysis of target genes and quantification of photophysiological metrics. We then examined how these attributes were regulated after the stressor was removed to assess the recovery potential of P. acuta. The fragments that were subjected to heat stress (2 °C above ambient levels) generally exhibited significant reduction in their endosymbiont densities, but the extent of recovery following stress removal varied depending on natal site and colony. There were minimal changes in chl a concentration and maximum quantum yield (Fv/Fm, the proportion of variable fluorescence (Fv) to maximum fluorescence (Fm)) in heat-stressed corals, suggesting that the algal endosymbionts' Photosystem II was not severely compromised. Significant changes in gene expression levels of selected genes of interest (GOI) were observed following heat exposure and stress removal among sites and colonies, including Actin, calcium/calmodulin-dependent protein kinase type IV (Camk4), kinesin-like protein (KIF9), and small heat shock protein 16.1 (Hsp16.1). The most responsive GOIs were Actin, a major component of the cytoskeleton, and the adaptive immune-related Camk4 which both showed significant reduction following heat exposure and subsequent upregulation during the recovery phase. Our findings clearly demonstrate specific responses of P. acuta in both photophysiological attributes and gene expression levels, suggesting differential capacity of P. acuta corals to tolerate heat stress depending on the colony, so that certain colonies may be more resilient than others.

RevDate: 2020-08-17

Pilgrim J, Siozios S, Baylis M, et al (2020)

The Tissue Tropisms and Transstadial Transmission of a Rickettsia Endosymbiont in the Highland Midge, Culicoides impunctatus (Diptera: Ceratopogonidae).

Applied and environmental microbiology pii:AEM.01492-20 [Epub ahead of print].

Rickettsia are a group of intracellular bacteria which can manipulate host reproduction and alter sensitivity to natural enemy attack in a diverse range of arthropods. The maintenance of Rickettsia endosymbionts in insect populations can be achieved through both vertical and horizontal transmission routes. For example, the presence of the symbiont in the follicle cells and salivary glands of Bemisia whiteflies allows Belli group Rickettsia transmission via the germline and plants, respectively. However, the transmission routes of other Rickettsia, such as those in the Torix group of the genus, remain underexplored. Through fluorescence in-situ hybridisation (FISH) and transmission electron microscopy (TEM) screening, this study describes the pattern of Torix Rickettsia tissue tropisms in the highland midge, Culicoides impunctatus (Diptera: Ceratopogonidae). Of note is high intensity of infection of the ovarian suspensory ligament, suggestive of a novel germline targeting strategy. Additionally, localisation of the symbiont in tissues of several developmental stages suggests transstadial transmission is a major route of ensuring maintenance of Rickettsia within C. impunctatus populations. Aside from providing insights into transmission strategies, Rickettsia presence in the fat body of larvae indicates potential host fitness and vector capacity impacts to be investigated in the future.Importance Statement Microbial symbionts of disease vectors have garnered recent attention due to their ability to alter vectorial capacity. Their consideration as a means of arbovirus control depends on symbiont vertical transmission which leads to spread of the bacteria through a population. Previous work has identified a Rickettsia symbiont present in several species of biting midges (Culicoides spp.), which transmit bluetongue and Schmallenberg arboviruses. However, symbiont transmission strategies and host effects remain underexplored. In this study, we describe the presence of Rickettsia in the ovarian suspensory ligament of Culicoides impunctatus Infection of this organ suggests the connective tissue surrounding developing eggs is important for ensuring vertical transmission of the symbiont in midges and possibly other insects. Additionally, our results indicate Rickettsia localisation in the fat body of Culicoides impunctatus As the arboviruses spread by midges often replicate in the fat body, this location implies possible symbiont-virus interactions to be further investigated.

RevDate: 2020-08-15

Martinez J, Klasson L, Welch JJ, et al (2020)

Life and death of selfish genes: comparative genomics reveals the dynamic evolution of cytoplasmic incompatibility.

Molecular biology and evolution pii:5892770 [Epub ahead of print].

Cytoplasmic incompatibility is a selfish reproductive manipulation induced by the endosymbiont Wolbachia in arthropods. In males Wolbachia modifies sperm, leading to embryonic mortality in crosses with Wolbachia-free females. In females, Wolbachia rescues the cross and allows development to proceed normally. This provides a reproductive advantage to infected females, allowing the maternally-transmitted symbiont to spread rapidly through host populations. We identified homologs of the genes underlying this phenotype, cifA and cifB, in 52 of 71 new and published Wolbachia genomes sequences. They are strongly associated with cytoplasmic incompatibility. There are up to seven copies of the genes in each genome, and phylogenetic analysis shows that Wolbachia frequently acquires new copies due to pervasive horizontal transfer between strains. In many cases the genes have subsequently acquired loss-of-function mutations to become pseudogenes. As predicted by theory, this tends to occur first in cifB, whose sole function is to modify sperm, and then in cifA, which is required to rescue the cross in females. Although cif genes recombine, recombination is largely restricted to closely related homologs. This is predicted under a model of coevolution between sperm modification and embryonic rescue, where recombination between distantly related pairs of genes would create a self-incompatible strain. Together, these patterns of gene gain, loss and recombination support evolutionary models of cytoplasmic incompatibility.

RevDate: 2020-08-13

Pavlinec Ž, Zupičić IG, Oraić D, et al (2020)

Assessment of predominant bacteria in noble pen shell (Pinna nobilis) collected in the Eastern Adriatic Sea.

Environmental monitoring and assessment, 192(9):581 pii:10.1007/s10661-020-08541-6.

Noble pen shell (Pinna nobilis) is an endemic species and the largest known bivalve in the Mediterranean Sea. By filtering large amounts of water, they maintain a high percentage of organic matter, hence playing an important role in the marine ecosystem. The ecological community of pen shells is impressive, and there are numerous microorganisms present in its soft tissues. Since this species is highly endangered due to recently described mass mortalities throughout the Mediterranean, this study was aimed at finding out more about its microbiome. In this study, we identified the predominant bacterial populations of specimens collected at three separate locations along the Eastern Adriatic coast. The predominant bacteria were isolated and 16S rRNA sequencing was performed to identify eight different bacterial genera: Aestuariibacter sp., Aliivibrio sp., Alteromonas sp., Marinobacter sp., Pseudoalteromonas sp., Rubritalea sp., Thalassospira sp. and the Vibrio splendidus clade. The identified genera are ubiquitous in the marine environment and have previously been described as both beneficial symbionts and potential pathogens in other molluscs. There was a clear difference in the predominant bacterial populations between northern and southern sampling sites, which could be linked to water temperature. These findings indicate the need for expanded sampling over a longer time period, since more exhaustive research would provide information vital to the conservation of this critically endangered species.

RevDate: 2020-08-13

Wong ML, Liew JWK, Wong WK, et al (2020)

Natural Wolbachia infection in field-collected Anopheles and other mosquito species from Malaysia.

Parasites & vectors, 13(1):414 pii:10.1186/s13071-020-04277-x.

BACKGROUND: The endosymbiont bacterium Wolbachia is maternally inherited and naturally infects some filarial nematodes and a diverse range of arthropods, including mosquito vectors responsible for disease transmission in humans. Previously, it has been found infecting most mosquito species but absent in Anopheles and Aedes aegypti. However, recently these two mosquito species were found to be naturally infected with Wolbachia. We report here the extent of Wolbachia infections in field-collected mosquitoes from Malaysia based on PCR amplification of the Wolbachia wsp and 16S rRNA genes.

METHODS: The prevalence of Wolbachia in Culicinae mosquitoes was assessed via PCR with wsp primers. For some of the mosquitoes, in which the wsp primers failed to amplify a product, Wolbachia screening was performed using nested PCR targeting the 16S rRNA gene. Wolbachia sequences were aligned using Geneious 9.1.6 software, analyzed with BLAST, and the most similar sequences were downloaded. Phylogenetic analyses were carried out with MEGA 7.0 software. Graphs were drawn with GraphPad Prism 8.0 software.

RESULTS: A total of 217 adult mosquitoes representing 26 mosquito species were screened. Of these, infections with Wolbachia were detected in 4 and 15 mosquito species using wsp and 16S rRNA primers, respectively. To our knowledge, this is the first time Wolbachia was detected using 16S rRNA gene amplification, in some Anopheles species (some infected with Plasmodium), Culex sinensis, Culex vishnui, Culex pseudovishnui, Mansonia bonneae and Mansonia annulifera. Phylogenetic analysis based on wsp revealed Wolbachia from most of the mosquitoes belonged to Wolbachia Supergroup B. Based on 16S rRNA phylogenetic analysis, the Wolbachia strain from Anopheles mosquitoes were more closely related to Wolbachia infecting Anopheles from Africa than from Myanmar.

CONCLUSIONS: Wolbachia was found infecting Anopheles and other important disease vectors such as Mansonia. Since Wolbachia can affect its host by reducing the life span and provide resistance to pathogen infection, several studies have suggested it as a potential innovative tool for vector/vector-borne disease control. Therefore, it is important to carry out further studies on natural Wolbachia infection in vector mosquitoes' populations as well as their long-term effects in new hosts and pathogen suppression.

RevDate: 2020-08-11

Curran DM, Grote A, Nursimulu N, et al (2020)

Modeling the metabolic interplay between a parasitic worm and its bacterial endosymbiont allows the identification of novel drug targets.

eLife, 9: pii:51850.

The filarial nematode Brugia malayi represents a leading cause of disability in the developing world, causing lymphatic filariasis in nearly 40 million people. Currently available drugs are not well-suited to mass drug administration efforts, so new treatments are urgently required. One potential vulnerability is the endosymbiotic bacteria Wolbachia-present in many filariae-which is vital to the worm. Genome scale metabolic networks have been used to study prokaryotes and protists and have proven valuable in identifying therapeutic targets, but have only been applied to multicellular eukaryotic organisms more recently. Here, we present iDC625, the first compartmentalized metabolic model of a parasitic worm. We used this model to show how metabolic pathway usage allows the worm to adapt to different environments, and predict a set of 102 reactions essential to the survival of B. malayi. We validated three of those reactions with drug tests and demonstrated novel antifilarial properties for all three compounds.

RevDate: 2020-08-10

Duan R, Xu H, Gao S, et al (2020)

Effects of Different Hosts on Bacterial Communities of Parasitic Wasp Nasonia vitripennis.

Frontiers in microbiology, 11:1435.

Parasitism is a special interspecific relationship in insects. Unlike most other ectoparasites, Nasonia vitripennis spend most of its life cycle (egg, larvae, pupae, and early adult stage) inside the pupae of flies, which is covered with hard puparium. Microbes play important roles in host development and help insect hosts to adapt to various environments. How the microbes of parasitic wasp respond to different fly hosts living in such close relationships motivated this investigation. In this study, we used N. vitripennis and three different fly pupa hosts (Lucilia sericata, Sarcophaga marshalli, and Musca domestica) to address this question, as well as to illustrate the potential transfer of bacteria through the trophic food chains. We found that N. vitripennis from different fly pupa hosts showed distinct microbiota, which means that the different fly hosts could affect the bacterial communities of their parasitic wasps. Some bacteria showed potential horizontal transfer through the trophic food chains, from the food through the fly to the parasitic wasp. We also found that the heritable endosymbiont Wolbachia could transferred from the fly host to the parasite and correlated with the bacterial communities of the corresponding parasitic wasps. Our findings provide new insight to the microbial interactions between parasite and host.

RevDate: 2020-08-07

Hu FY, CW Tsai (2020)

Nutritional Relationship between Bemisia tabaci and Its Primary Endosymbiont, Portiera aleyrodidarum, during Host Plant Acclimation.

Insects, 11(8): pii:insects11080498.

Plant sap-sucking insects commonly have established mutualistic relationships with endosymbiotic bacteria that can provide nutrients lacking in their diet. Bemisia tabaci harbors one primary endosymbiont, Portiera aleyrodidarum, and up to seven secondary endosymbionts, including Hamiltonella defensa and Rickettsia sp. Portiera aleyrodidarum is already known to play a critical role in providing necessary nutrients for B. tabaci. In the present study, the relationship among B. tabaci, its primary endosymbiont, and the host plant were examined through the effects of host plant shifting and acclimation. Bemisia tabaci was transferred from Chinese kale to four different host plants, and the effects on both its performance and the expression levels of nutrient-related genes of P. aleyrodidarum were analyzed. The results showed that host shifting from Chinese kale to cotton plants led to a decrease in the performance of B. tabaci in the first generation, which was restored after 10 generations of acclimation. Furthermore, the expression levels of essential amino acid biosynthesis genes of P. aleyrodidarum were found to be differentially regulated after B. tabaci had acclimated to the cotton plants. Host plant shifting and acclimation to cucumber, poinsettia, and tomato plants did not affect the fecundity of B. tabaci and the expression levels of most examined genes. We speculate that P. aleyrodidarum may help B. tabaci improve its performance and acclimate to new hosts and that P. aleyrodidarum has a close nutritional relationship with its host during host plant acclimation.

RevDate: 2020-08-04

Ashour DS, AA Othman (2020)

Parasite-bacteria interrelationship.

Parasitology research pii:10.1007/s00436-020-06804-2 [Epub ahead of print].

Parasites and bacteria have co-evolved with humankind, and they interact all the time in a myriad of ways. For example, some bacterial infections result from parasite-dwelling bacteria as in the case of Salmonella infection during schistosomiasis. Other bacteria synergize with parasites in the evolution of human disease as in the case of the interplay between Wolbachia endosymbiont bacteria and filarial nematodes as well as the interaction between Gram-negative bacteria and Schistosoma haematobium in the pathogenesis of urinary bladder cancer. Moreover, secondary bacterial infections may complicate several parasitic diseases such as visceral leishmaniasis and malaria, due to immunosuppression of the host during parasitic infections. Also, bacteria may colonize the parasitic lesions; for example, hydatid cysts and skin lesions of ectoparasites. Remarkably, some parasitic helminths and arthropods exhibit antibacterial activity usually by the release of specific antimicrobial products. Lastly, some parasite-bacteria interactions are induced as when using probiotic bacteria to modulate the outcome of a variety of parasitic infections. In sum, parasite-bacteria interactions involve intricate processes that never cease to intrigue the researchers. However, understanding and exploiting these interactions could have prophylactic and curative potential for infections by both types of pathogens.

RevDate: 2020-08-01

Takamatsu T, Arai H, Abe N, et al (2020)

Coexistence of Two Male-Killers and Their Impact on the Development of Oriental Tea Tortrix Homona magnanima.

Microbial ecology pii:10.1007/s00248-020-01566-x [Epub ahead of print].

Male-killing, the death of male offspring induced by maternally transmitted microbes, is classified as early, or late, male-killing. The primary advantage afforded by early male-killing, which typically occurs during embryogenesis, is the reallocation of resources to females, that would have otherwise been consumed by males. Meanwhile, the key advantage of late male-killing, which typically occurs during late larval development, is the maximized potential for horizontal transmission. To date, no studies have reported on the associated developmental and physiological effects of host coinfection with early and late male-killers, which may have a significant impact on the population dynamics of the male-killers. Here we used a lepidopteran tea pest Homona magnanima as a model, which is a unique system wherein an early male-killer (a Spiroplasma bacterium) and a late male-killer (an RNA virus) can coexist in nature. An artificially established matriline, coinfected with both Spiroplasma and RNA virus, exhibited embryonic death (early male-killing) as seen in the host line singly infected with Spiroplasma. Moreover, the coinfected line also exhibited developmental retardation and low pupal weight similar to the host line singly infected with the RNA virus. A series of field surveys revealed that Spiroplasma-RNA virus coinfection occurs in nature at a low frequency. Hence, although the two male-killers are capable of coexisting within the H. magnanima population independently, high associated fitness cost appears to limit the prevalence of male-killer coinfection in the field host population.

RevDate: 2020-07-31

Pasqualetti C, Szokoli F, Rindi L, et al (2020)

The Obligate Symbiont "Candidatus Megaira polyxenophila" Has Variable Effects on the Growth of Different Host Species.

Frontiers in microbiology, 11:1425.

"Candidatus Megaira polyxenophila" is a recently described member of Rickettsiaceae which comprises exclusively obligate intracellular bacteria. Interestingly, these bacteria can be found in a huge diversity of eukaryotic hosts (protist, green algae, metazoa) living in marine, brackish or freshwater habitats. Screening of amplicon datasets revealed a high frequency of these bacteria especially in freshwater environments, most likely associated to eukaryotic hosts. The relationship of "Ca. Megaira polyxenophila" with their hosts and their impact on host fitness have not been studied so far. Even less is known regarding the responses of these intracellular bacteria to potential stressors. In this study, we used two phylogenetically close species of the freshwater ciliate Paramecium, Paramecium primaurelia and Paramecium pentaurelia (Ciliophora, Oligohymenophorea) naturally infected by "Ca. Megaira polyxenophila". In order to analyze the effect of the symbiont on the fitness of these two species, we compared the growth performance of both infected and aposymbiotic paramecia at different salinity levels in the range of freshwater and oligohaline brackish water i.e., at 0, 2, and 4.5 ppt. For the elimination of "Ca. Megaira polyxenophila" we established an antibiotic treatment to obtain symbiont-free lines and confirmed its success by fluorescence in situ hybridization (FISH). The population and infection dynamics during the growth experiment were observed by cell density counts and FISH. Paramecia fitness was compared applying generalized additive mixed models. Surprisingly, both infected Paramecium species showed higher densities under all salinity concentrations. The tested salinity concentrations did not significantly affect the growth of any of the two species directly, but we observed the loss of the endosymbiont after prolonged exposure to higher salinity levels. This experimental data might explain the higher frequency of "Ca. M. polyxenophila" in freshwater habitats as observed from amplicon data.

RevDate: 2020-07-31

Sato Y, Wippler J, Wentrup C, et al (2020)

High-Quality Draft Genome Sequences of the Uncultured Delta3 Endosymbiont (Deltaproteobacteria) Assembled from Metagenomes of the Gutless Marine Worm Olavius algarvensis.

Microbiology resource announcements, 9(31): pii:9/31/e00704-20.

Here, we present two high-quality, draft metagenome-assembled genomes of deltaproteobacterial OalgDelta3 endosymbionts from the gutless marine worm Olavius algarvensis Their 16S rRNA gene sequences share 98% identity with Delta3 endosymbionts of related host species Olavius ilvae (GenBank accession no. AJ620501) and Inanidrilus exumae (GenBank accession no. FM202060), for which no symbiont genomes are available.

RevDate: 2020-07-31

Satta CT, Pulina S, Reñé A, et al (2020)

Ecological, morphological and molecular characterization of Kryptoperidinium sp. (Dinophyceae) from two Mediterranean coastal shallow lagoons.

Harmful algae, 97:101855.

In this study, the field ecology of Kryptoperidinium sp. was examined in two Mediterranean shallow lagoons, Calich (CA) and Santa Giusta (SG) in Sardinia, Italy. Kryptoperidinium cell density and the environmental conditions were examined monthly from 2008 to 2015 in CA and from 2011 to 2016 in SG. Cell morphology was determined by observing specimens taken from the field and from cultures that were established by single-cell isolation from samples collected in the two lagoons. The molecular identity of strains from each lagoon was also ascertained. The growth rates of the strains were determined under three different temperature conditions and six salinity treatments. The two wild populations shared the same morphology and the cultured strains were morphologically and molecularly identical. The SSU and 5.8S phylogenies show the presence of two clusters within the available Kryptoperidinium sequences and the strains obtained in this study clustered with others from the Mediterranean and Baltic. The multiannual dynamics of Kryptoperidinium sp. in the field significantly differed in the two lagoons, showing much higher cell densities in CA than in SG. The presence of Kryptoperidinium sp. was detected throughout the year in CA, with recurrent blooms also affecting the adjacent coastal area. In contrast, Kryptoperidinium sp. was sporadically observed in SG. The variation in the environmental parameters was fairly wide during the presence and blooms of Kryptoperidinium sp., especially in CA. The application of Generalized Linear Models to the field data revealed a significant role of rainfall and dissolved inorganic nitrogen on the presence and blooms of the species. Although growth rates were similar between the two strains, significant differences were detected for the 10 and 40 salinity treatments. The results obtained in this study add to our knowledge about the ecology of a harmful species that is not well understood in transitional ecosystems such as Mediterranean lagoons.

RevDate: 2020-07-31

Garrido C, Caspari OD, Choquet Y, et al (2020)

Evidence Supporting an Antimicrobial Origin of Targeting Peptides to Endosymbiotic Organelles.

Cells, 9(8): pii:cells9081795.

Mitochondria and chloroplasts emerged from primary endosymbiosis. Most proteins of the endosymbiont were subsequently expressed in the nucleo-cytosol of the host and organelle-targeted via the acquisition of N-terminal presequences, whose evolutionary origin remains enigmatic. Using a quantitative assessment of their physico-chemical properties, we show that organelle targeting peptides, which are distinct from signal peptides targeting other subcellular compartments, group with a subset of antimicrobial peptides. We demonstrate that extant antimicrobial peptides target a fluorescent reporter to either the mitochondria or the chloroplast in the green alga Chlamydomonas reinhardtii and, conversely, that extant targeting peptides still display antimicrobial activity. Thus, we provide strong computational and functional evidence for an evolutionary link between organelle-targeting and antimicrobial peptides. Our results support the view that resistance of bacterial progenitors of organelles to the attack of host antimicrobial peptides has been instrumental in eukaryogenesis and in the emergence of photosynthetic eukaryotes.

RevDate: 2020-07-30

Tabima JF, Trautman IA, Chang Y, et al (2020)

Phylogenomic Analyses of Non-Dikarya Fungi Supports Horizontal Gene Transfer Driving Diversification of Secondary Metabolism in the Amphibian Gastrointestinal Symbiont, Basidiobolus.

G3 (Bethesda, Md.) pii:g3.120.401516 [Epub ahead of print].

Research into secondary metabolism (SM) production by fungi has resulted in the discovery of diverse, biologically active compounds with significant medicinal applications. The fungi rich in SM production are taxonomically concentrated in the subkingdom Dikarya, which comprises the phyla Ascomycota and Basidiomycota. Here, we explore the potential for SM production in Mucoromycota and Zoopagomycota, two phyla of nonflagellated fungi that are not members of Dikarya, by predicting and identifying core genes and gene clusters involved in SM. The majority of non-Dikarya have few genes and gene clusters involved in SM production except for the amphibian gut symbionts in the genus BasidiobolusBasidiobolus genomes exhibit an enrichment of SM genes involved in siderophore, surfactin-like, and terpene cyclase production, all these with evidence of constitutive gene expression. Gene expression and chemical assays also confirm that Basidiobolus has significant siderophore activity. The expansion of SMs in Basidiobolus are partially due to horizontal gene transfer from bacteria, likely as a consequence of its ecology as an amphibian gut endosymbiont.

RevDate: 2020-07-29

Fraser JE, O'Donnell TB, Duyvestyn JM, et al (2020)

Novel phenotype of Wolbachia strain wPip in Aedes aegypti challenges assumptions on mechanisms of Wolbachia-mediated dengue virus inhibition.

PLoS pathogens, 16(7):e1008410 pii:PPATHOGENS-D-20-00256 [Epub ahead of print].

The bacterial endosymbiont Wolbachia is a biocontrol tool that inhibits the ability of the Aedes aegypti mosquito to transmit positive-sense RNA viruses such as dengue and Zika. Growing evidence indicates that when Wolbachia strains wMel or wAlbB are introduced into local mosquito populations, human dengue incidence is reduced. Despite the success of this novel intervention, we still do not fully understand how Wolbachia protects mosquitoes from viral infection. Here, we demonstrate that the Wolbachia strain wPip does not inhibit virus infection in Ae. aegypti. We have leveraged this novel finding, and a panel of Ae. aegypti lines carrying virus-inhibitory (wMel and wAlbB) and non-inhibitory (wPip) strains in a common genetic background, to rigorously test a number of hypotheses about the mechanism of Wolbachia-mediated virus inhibition. We demonstrate that, contrary to previous suggestions, there is no association between a strain's ability to inhibit dengue infection in the mosquito and either its typical density in the midgut or salivary glands, or the degree to which it elevates innate immune response pathways in the mosquito. These findings, and the experimental platform provided by this panel of genetically comparable mosquito lines, clear the way for future investigations to define how Wolbachia prevents Ae. aegypti from transmitting viruses.

RevDate: 2020-07-29

Maire J, Parisot N, Galvao Ferrarini M, et al (2020)

Spatial and morphological reorganization of endosymbiosis during metamorphosis accommodates adult metabolic requirements in a weevil.

Proceedings of the National Academy of Sciences of the United States of America pii:2007151117 [Epub ahead of print].

Bacterial intracellular symbiosis (endosymbiosis) is widespread in nature and impacts many biological processes. In holometabolous symbiotic insects, metamorphosis entails a complete and abrupt internal reorganization that creates a constraint for endosymbiont transmission from larvae to adults. To assess how endosymbiosis copes-and potentially evolves-throughout this major host-tissue reorganization, we used the association between the cereal weevil Sitophilus oryzae and the bacterium Sodalis pierantonius as a model system. S. pierantonius are contained inside specialized host cells, the bacteriocytes, that group into an organ, the bacteriome. Cereal weevils require metabolic inputs from their endosymbiont, particularly during adult cuticle synthesis, when endosymbiont load increases dramatically. By combining dual RNA-sequencing analyses and cell imaging, we show that the larval bacteriome dissociates at the onset of metamorphosis and releases bacteriocytes that undergo endosymbiosis-dependent transcriptomic changes affecting cell motility, cell adhesion, and cytoskeleton organization. Remarkably, bacteriocytes turn into spindle cells and migrate along the midgut epithelium, thereby conveying endosymbionts to midgut sites where future mesenteric caeca will develop. Concomitantly, endosymbiont genes encoding a type III secretion system and a flagellum apparatus are transiently up-regulated while endosymbionts infect putative stem cells and enter their nuclei. Infected cells then turn into new differentiated bacteriocytes and form multiple new bacteriomes in adults. These findings show that endosymbiosis reorganization in a holometabolous insect relies on a synchronized host-symbiont molecular and cellular "choreography" and illustrates an adaptive feature that promotes bacteriome multiplication to match increased metabolic requirements in emerging adults.

RevDate: 2020-07-27

Lindsey ARI (2020)

Sensing, Signaling, and Secretion: A Review and Analysis of Systems for Regulating Host Interaction in Wolbachia.

Genes, 11(7): pii:genes11070813.

Wolbachia (Anaplasmataceae) is an endosymbiont of arthropods and nematodes that resides within host cells and is well known for manipulating host biology to facilitate transmission via the female germline. The effects Wolbachia has on host physiology, combined with reproductive manipulations, make this bacterium a promising candidate for use in biological- and vector-control. While it is becoming increasingly clear that Wolbachia's effects on host biology are numerous and vary according to the host and the environment, we know very little about the molecular mechanisms behind Wolbachia's interactions with its host. Here, I analyze 29 Wolbachia genomes for the presence of systems that are likely central to the ability of Wolbachia to respond to and interface with its host, including proteins for sensing, signaling, gene regulation, and secretion. Second, I review conditions under which Wolbachia alters gene expression in response to changes in its environment and discuss other instances where we might hypothesize Wolbachia to regulate gene expression. Findings will direct mechanistic investigations into gene regulation and host-interaction that will deepen our understanding of intracellular infections and enhance applied management efforts that leverage Wolbachia.

RevDate: 2020-07-22

Suhag A, Yadav H, Chaudhary D, et al (2020)

Biotechnological interventions for the sustainable management of a global pest, whitefly (Bemisia tabaci).

Insect science [Epub ahead of print].

Whiteflies (Bemisia tabaci) are polyphagous invasive hemipteran insects that cause serious losses of important crops by directly feeding on phloem sap and transmitting pathogenic viruses. These insects have emerged as a major threat to global agriculture and food security. Chemically synthesized insecticides are currently the only option to control whiteflies, but the ability of whiteflies to evolve resistance against insecticides has made the management of these insects very difficult. Natural host-plant resistance against whiteflies identified in some crop plants has not been exploited to a great extent. Genetic engineering approaches, such as transgenics and RNA interference (RNAi), are potentially useful for the control of whiteflies. Transgenic plants harboring insecticidal toxins/lectins developed via nuclear or chloroplast transformation are a promising vehicle for whitefly control. Double-stranded RNAs (dsRNAs) of several insect genes, delivered either through microinjection into the insect body cavity or orally via an artificial diet and transiently or stably expressed in transgenic plants, have controlled whiteflies in model plants and in some crops at the laboratory level, but not at the field level. In this review, we highlight the merits and demerits of each delivery method along with strategies for sustained delivery of dsRNAs via fungal entomopathogen/endosymbiont or non-transgenic RNAi approaches, foliar sprays, root absorption or nanocarriers as well as the factors affecting efficient RNAi and their biosafety issues. Genome sequencing and transcriptome studies of whitefly species are facilitating the selection of appropriate genes for RNAi and gene-editing technology for the efficient and resilient management of whiteflies and their transmitted viruses. This article is protected by copyright. All rights reserved.

RevDate: 2020-07-21

Jorrin B, Palacios JM, Peix Á, et al (2020)

Rhizobium ruizarguesonis sp. nov., isolated from nodules of Pisum sativum L.

Systematic and applied microbiology, 43(4):126090.

Four strains, coded as UPM1132, UPM1133T, UPM1134 and UPM1135, and isolated from nodules of Pisum sativum plants grown on Ni-rich soils were characterised through a polyphasic taxonomy approach. Their 16S rRNA gene sequences were identical and showed 100% similarity with their closest phylogenetic neighbors, the species included in the 'R. leguminosarum group': R. laguerreae FB206T, R. leguminosarum USDA 2370T, R. anhuiense CCBAU 23252T, R. sophoreae CCBAU 03386T, R. acidisoli FH13T and R. hidalgonense FH14T, and 99.6% sequence similarity with R. esperanzae CNPSo 668T. The analysis of combined housekeeping genes recA, atpD and glnII sequences showed similarities of 92-95% with the closest relatives. Whole genome average nucleotide identity (ANI) values were 97.5-99.7% ANIb similarity among the four strains, and less than 92.4% with closely related species, while digital DNA-DNA hybridization average values (dDDH) were 82-85% within our strains and 34-52% with closely related species. Major fatty acids in strain UPM1133T were C18:1 ω7c / C18:1 ω6c in summed feature 8, C14:0 3OH/ C16:1 iso I in summed feature 2 and C18:0. Colonies were small to medium, pearl-white coloured in YMA at 28°C and growth was observed in the ranges 8-34°C, pH 5.5-7.5 and 0-0.7% (w/v) NaCl. The DNA G+C content was 60.8mol %. The combined genotypic, phenotypic and chemotaxonomic data support the classification of strains UPM1132, UPM1133T, UPM1134 and UPM1135 into a novel species of Rhizobium, for which the name Rhizobium ruizarguesonis sp. nov. is proposed. The type strain is UPM1133T (=CECT 9542T=LMG 30526T).

RevDate: 2020-07-21

Huang EYY, Wong AYP, Lee IHT, et al (2020)

Infection patterns of dengue, Zika and endosymbiont Wolbachia in the mosquito Aedes albopictus in Hong Kong.

Parasites & vectors, 13(1):361 pii:10.1186/s13071-020-04231-x.

BACKGROUND: The mosquito Aedes albopictus is a vector of dengue and Zika viruses. Insecticide-resistant mosquito populations have evolved in recent decades, suggesting that new control strategies are needed. Hong Kong has a monsoon-influenced humid subtropical climate, which favours the spread of mosquitoes. However, baseline information on the composition and dynamics of the occurrence of endosymbiont Wolbachia in local Ae. albopictus is lacking, hindering the development of scientifically-informed control measures. This study identifies the presence and absence of dengue and Zika viruses, and Wolbachia infection in Aedes albopictus in Hong Kong.

METHODS: Oviposition traps were set at 57 areas in Hong Kong, and both immature and adult mosquitoes were collected on a monthly basis between April 2018 and April 2019 as the study sample. Each individual mosquito in this sample was processed and screened for the presence of the dengue and Zika viruses and the endosymbionts Wolbachia wAlbA and wAlbB with PCR.

RESULTS: Totals of 967 and 984 mosquitoes were tested respectively for the presence of dengue and Zika viruses, and no trace of either infection was found in these samples. The presence of wAlbA and wAlbB was also tested in 1582 individuals. Over 80% of these individuals were found to be stably infected with Wolbachia throughout the thirteen-month collection period (~ 47% singly-infected; ~ 36.8% doubly infected with both wAlbA and wAlbB).

CONCLUSIONS: The high degree of Wolbachia wAlbA and wAlbB infection in Ae. albopictus mosquitoes in Hong Kong, coupled with the absence of any signs of infection by dengue and Zika viruses, contrasts significantly with the pattern of mosquito infection in other parts of Asia. Further studies of the infection pattern in local mosquitoes are warranted before mosquito control strategies used in other regions are implemented in Hong Kong.

RevDate: 2020-07-21

Morrow JL, Om N, Beattie GAC, et al (2020)

Characterization of the bacterial communities of psyllids associated with Rutaceae in Bhutan by high throughput sequencing.

BMC microbiology, 20(1):215 pii:10.1186/s12866-020-01895-4.

BACKGROUND: Several plant-pathogenic bacteria are transmitted by insect vector species that often also act as hosts. In this interface, these bacteria encounter plant endophytic, insect endosymbiotic and other microbes. Here, we used high throughput sequencing to examine the bacterial communities of five different psyllids associated with citrus and related plants of Rutaceae in Bhutan: Diaphorina citri, Diaphorina communis, Cornopsylla rotundiconis, Cacopsylla heterogena and an unidentified Cacopsylla sp.

RESULTS: The microbiomes of the psyllids largely comprised their obligate P-endosymbiont 'Candidatus Carsonella ruddii', and one or two S-endosymbionts that are fixed and specific to each lineage. In addition, all contained Wolbachia strains; the Bhutanese accessions of D. citri were dominated by a Wolbachia strain first found in American isolates of D. citri, while D. communis accessions were dominated by the Wolbachia strain, wDi, first detected in D. citri from China. The S-endosymbionts from the five psyllids grouped with those from other psyllid taxa; all D. citri and D. communis individuals contained sequences matching 'Candidatus Profftella armatura' that has previously only been reported from other Diaphorina species, and the remaining psyllid species contained OTUs related to unclassified Enterobacteriaceae. The plant pathogenic 'Candidatus Liberibacter asiaticus' was found in D. citri but not in D. communis. Furthermore, an unidentified 'Candidatus Liberibacter sp.' occurred at low abundance in both Co. rotundiconis and the unidentified Cacopsylla sp. sampled from Zanthoxylum sp.; the status of this new liberibacter as a plant pathogen and its potential plant hosts are currently unknown. The bacterial communities of Co. rotundiconis also contained a range of OTUs with similarities to bacteria previously found in samples taken from various environmental sources.

CONCLUSIONS: The bacterial microbiota detected in these Bhutanese psyllids support the trends that have been seen in previous studies: psyllids have microbiomes largely comprising their obligate P-endosymbiont and one or two S-endosymbionts. In addition, the association with plant pathogens has been demonstrated, with the detection of liberibacters in a known host, D. citri, and identification of a putative new species of liberibacter in Co. rotundiconis and Cacopsylla sp.

RevDate: 2020-07-17

Park J, Xi H, Park J, et al (2020)

Complete Genome Sequence of the Blochmannia Endosymbiont of Camponotus nipponensis.

Microbiology resource announcements, 9(29): pii:9/29/e00703-20.

Blochmannia endosymbionts, belonging to Gammaproteobacteria, live in bacteriocytes, which are specialized cells for these bacterial species in the Camponotus genus (carpenter ants). In this announcement, we describe the complete genome sequence of the Blochmannia endosymbiont of Camponotus nipponensis, which originated from a C. nipponensis colony collected in the Republic of Korea.

RevDate: 2020-07-17

Higazi TB, Geary TG, CD Mackenzie (2014)

Chemotherapy in the treatment, control, and elimination of human onchocerciasis.

Research and reports in tropical medicine, 5:77-93.

Onchocerciasis treatment is one of the most positive stories in tropical medicine although major challenges remain to reaching the ultimate goal of disease elimination. Such challenges are to be expected when the therapeutic goal is to kill and safely remove a large multistage, efficient, metazoan infectious agent such as Onchocerca volvulus that has an exceptionally complicated relationship with its host. Successful control of onchocerciasis has often been hampered by host reactions following chemotherapy, that can sometimes cause significant tissue pathology. Presence of other filariae, particularly Loa loa, in endemic onchocerciasis-treatment areas also poses severe problems due to adverse reactions caused by drug-induced death of the coincident microfilariae of this usually clinically benign species. Although ivermectin has been very successful, there is a need to enhance the progress toward elimination of onchocerciasis; new drugs and their efficient use are keys to this. The permanent absence of Onchocerca microfilaridermia, defined as the lack of resurgence of skin microfilarial loads after treatment, is the ultimate characteristic of a useful new chemotherapeutic agent. Several drugs are under investigation to achieve this, including the reassessment of currently available and previously tested agents, such as the antibiotic, doxycycline, which targets the adult parasites through its anti-Wolbachia endosymbiont activity. Flubendazole, a benzimidazole derivative approved for treatment of human gastrointestinal nematodes, is also being considered for repurposing as a macrofilaricide to aid in the achievement of eradication. The managerial challenges existing at the population level also need to be addressed; these include drug-distribution fatigue, the need to include noncompliant people, civil unrest in endemic areas, political cross-border issues, restrictions of age and pregnancy, and complications due to integration with other treatment programs. It is likely that a panel of chemotherapeutic options, new and old, supported by strong and effective distribution systems will be the best way to address challenges of treatment and elimination of this infection. Future research should also address management of treatment and control, and consider how new treatment paradigms can be incorporated to meet time lines set for global elimination by 2025.

RevDate: 2020-07-14

Fan L, Wu D, Goremykin V, et al (2020)

Phylogenetic analyses with systematic taxon sampling show that mitochondria branch within Alphaproteobacteria.

Nature ecology & evolution pii:10.1038/s41559-020-1239-x [Epub ahead of print].

Though it is well accepted that mitochondria originated from an alphaproteobacteria-like ancestor, the phylogenetic relationship of the mitochondrial endosymbiont to extant Alphaproteobacteria is yet unresolved. The focus of much debate is whether the affinity between mitochondria and fast-evolving alphaproteobacterial lineages reflects true homology or artefacts. Approaches such as site exclusion have been claimed to mitigate compositional heterogeneity between taxa, but this comes at the cost of information loss, and the reliability of such methods is so far unproven. Here we demonstrate that site-exclusion methods produce erratic phylogenetic estimates of mitochondrial origin. Thus, previous phylogenetic hypotheses on the origin of mitochondria based on pretreated datasets should be re-evaluated. We applied alternative strategies to reduce phylogenetic noise by systematic taxon sampling while keeping site substitution information intact. Cross-validation based on a series of trees placed mitochondria robustly within Alphaproteobacteria, sharing an ancient common ancestor with Rickettsiales and currently unclassified marine lineages.

RevDate: 2020-07-08

Gunderson EL, Vogel I, Chappell L, et al (2020)

The endosymbiont Wolbachia rebounds following antibiotic treatment.

PLoS pathogens, 16(7):e1008623 pii:PPATHOGENS-D-20-00474 [Epub ahead of print].

Antibiotic treatment has emerged as a promising strategy to sterilize and kill filarial nematodes due to their dependence on their endosymbiotic bacteria, Wolbachia. Several studies have shown that novel and FDA-approved antibiotics are efficacious at depleting the filarial nematodes of their endosymbiont, thus reducing female fecundity. However, it remains unclear if antibiotics can permanently deplete Wolbachia and cause sterility for the lifespan of the adult worms. Concerns about resistance arising from mass drug administration necessitate a careful exploration of potential Wolbachia recrudescence. In the present study, we investigated the long-term effects of the FDA-approved antibiotic, rifampicin, in the Brugia pahangi jird model of infection. Initially, rifampicin treatment depleted Wolbachia in adult worms and simultaneously impaired female worm fecundity. However, during an 8-month washout period, Wolbachia titers rebounded and embryogenesis returned to normal. Genome sequence analyses of Wolbachia revealed that despite the population bottleneck and recovery, no genetic changes occurred that could account for the rebound. Clusters of densely packed Wolbachia within the worm's ovarian tissues were observed by confocal microscopy and remained in worms treated with rifampicin, suggesting that they may serve as privileged sites that allow Wolbachia to persist in worms while treated with antibiotic. To our knowledge, these clusters have not been previously described and may be the source of the Wolbachia rebound.

RevDate: 2020-07-08

Rosenwald LC, Sitvarin MI, JA White (2020)

Endosymbiotic Rickettsiella causes cytoplasmic incompatibility in a spider host.

Proceedings. Biological sciences, 287(1930):20201107.

Many arthropod hosts are infected with bacterial endosymbionts that manipulate host reproduction, but few bacterial taxa have been shown to cause such manipulations. Here, we show that a bacterial strain in the genus Rickettsiella causes cytoplasmic incompatibility (CI) between infected and uninfected hosts. We first surveyed the bacterial community of the agricultural spider Mermessus fradeorum (Linyphiidae) using high throughput sequencing and found that individual spiders can be infected with up to five different strains of maternally inherited symbiont from the genera Wolbachia, Rickettsia, and Rickettsiella. The Rickettsiella strain was pervasive, found in all 23 tested spider matrilines. We used antibiotic curing to generate uninfected matrilines that we reciprocally crossed with individuals infected only with Rickettsiella. We found that only 13% of eggs hatched when uninfected females were mated with Rickettsiella-infected males; in contrast, at least 83% of eggs hatched in the other cross types. This is the first documentation of Rickettsiella, or any Gammaproteobacteria, causing CI. We speculate that induction of CI may be much more widespread among maternally inherited bacteria than previously appreciated. Further, our results reinforce the importance of thoroughly characterizing and assessing the inherited microbiome before attributing observed host phenotypes to well-characterized symbionts such as Wolbachia.

RevDate: 2020-07-04

Heryanto C, I Eleftherianos (2020)

Nematode endosymbiont competition: Fortune favors the fittest.

Molecular and biochemical parasitology pii:S0166-6851(20)30062-1 [Epub ahead of print].

Endosymbiotic bacteria that obligately associate with entomopathogenic nematodes as a complex are a unique model system to study competition. These nematodes seek an insect host and provide entry for their endosymbionts. Through their natural products, the endosymbionts nurture their nematodes by eliminating secondary infection, providing nutrients through bioconversion of the insect cadaver, and facilitating reproduction. On one hand, they cooperatively colonize the insect host and neutralize other opportunistic biotic threats. On the other hand, inside the insect cadaver as a fighting pit, they fiercely compete for the fittest partnership that will grant them the reproductive dominance. Here, we review the protective and nurturing nature of endosymbiotic bacteria for their nematodes and how their selective preference shapes the superior nematode-endosymbiont pairs as we know today.

RevDate: 2020-07-03

Lebov JF, Mattick J, Libro S, et al (2020)

Complete Genome Sequence of wBp, the Wolbachia Endosymbiont of Brugia pahangi FR3.

Microbiology resource announcements, 9(27): pii:9/27/e00480-20.

Lymphatic filariasis is a devastating disease caused by filarial nematode roundworms, which contain obligate Wolbachia endosymbionts. Here, we assembled the genome of wBp, the Wolbachia endosymbiont of the filarial nematode Brugia pahangi, from Illumina, Pacific Biosciences, and Oxford Nanopore data. The complete, circular genome is 1,072,967 bp.

RevDate: 2020-07-03

Duan XZ, Sun JT, Wang LT, et al (2020)

Recent infection by Wolbachia alters microbial communities in wild Laodelphax striatellus populations.

Microbiome, 8(1):104 pii:10.1186/s40168-020-00878-x.

BACKGROUND: Host-associated microbial communities play an important role in the fitness of insect hosts. However, the factors shaping microbial communities in wild populations, including genetic background, ecological factors, and interactions among microbial species, remain largely unknown.

RESULTS: Here, we surveyed microbial communities of the small brown planthopper (SBPH, Laodelphax striatellus) across 17 geographical populations in China and Japan by using 16S rRNA amplicon sequencing. Using structural equation models (SEM) and Mantel analyses, we show that variation in microbial community structure is likely associated with longitude, annual mean precipitation (Bio12), and mitochondrial DNA variation. However, a Wolbachia infection, which is spreading to northern populations of SBPH, seems to have a relatively greater role than abiotic factors in shaping microbial community structure, leading to sharp decreases in bacterial taxon diversity and abundance in host-associated microbial communities. Comparative RNA-Seq analyses between Wolbachia-infected and -uninfected strains indicate that the Wolbachia do not seem to alter the immune reaction of SBPH, although Wolbachia affected expression of metabolism genes.

CONCLUSION: Together, our results identify potential factors and interactions among different microbial species in the microbial communities of SBPH, which can have effects on insect physiology, ecology, and evolution. Video Abstract.

RevDate: 2020-07-02

Tay HW, Ng KT, Namkabir S, et al (2020)

An Unwanted Kiss by Charlie Beetle: An Unusual Case Report.

Pederin, a vesicant chemical and one of the most powerful animal toxins in the world, is produced by an endosymbiont bacteria (Pseudomonas spp) found on the beetle Paederus fuscipes. This small, red- and black-striped beetle is also commonly known as the Charlie or rove beetle. Accidental contact with skin causes Paederus dermatitis, with the clinical presentation ranging from mild dermatitis to more severe vesiculobullous lesions. We report a rare case of severe lip destruction caused by the Charlie beetle in a 24-year-old man. Treatment involved intravenous antibiotics in addition to local wound debridement. The thinner stratum corneum on the lips and close proximity to the oral cavity could have resulted in the severe tissue destruction encountered.

RevDate: 2020-06-29

Ferreira AG, Fairlie S, LA Moreira (2020)

Insect vectors endosymbionts as solutions against diseases.

Current opinion in insect science, 40:56-61 pii:S2214-5745(20)30078-X [Epub ahead of print].

Viral diseases transmitted by mosquitoes, known as arboviruses, pose a significant threat to human life and are a major burden on many health systems around the world. Currently, arbovirus control strategies rely on insecticides or vector source reduction and, in the absence of effective, accessible and affordable vaccines, mainly on symptomatic based, non-specific treatments. However, insecticides have the potential to interfere with non-target organisms, cause environmental toxicity and insecticide resistance reduces their effectiveness as a sustainable control method. Complementary and sustainable strategies are urgently needed. Wolbachia, an invertebrate endosymbiont, has been used as an alternative strategy for arboviral control, through suppression or modification of mosquito populations. Here we discuss the burden that arboviruses impose on human populations and how Wolbachia can be used as a sustainable strategy for control, in alignment with the United Nations- 2030 Agenda for Sustainable Development.

RevDate: 2020-06-27

Sproles AE, Oakley CA, Krueger T, et al (2020)

Sub-cellular imaging shows reduced photosynthetic carbon and increased nitrogen assimilation by the non-native endosymbiont Durusdinium trenchii in the model cnidarian Aiptasia.

Environmental microbiology [Epub ahead of print].

Hosting different symbiont species can affect inter-partner nutritional fluxes within the cnidarian-dinoflagellate symbiosis. Using nanoscale secondary ion mass spectrometry (NanoSIMS), we measured the spatial incorporation of photosynthetically-fixed 13 C and heterotrophically-derived 15 N into host and symbiont cells of the model symbiotic cnidarian Aiptasia (Exaiptasia pallida) when colonised with its native symbiont Breviolum minutum or the non-native Durusdinium trenchii. B. minutum exhibited high photosynthetic carbon assimilation per cell and translocation to host tissue throughout symbiosis establishment, while D. trenchii assimilated significantly less carbon, but obtained more host nitrogen. These findings suggest that D. trenchii has less potential to provide photosynthetically-fixed carbon to the host despite obtaining considerable amounts of heterotrophically-derived nitrogen. These sub-cellular events help explain previous observations that demonstrate differential effects of D. trenchii compared to B. minutum on the host transcriptome, proteome, metabolome, and host growth and asexual reproduction. Together, these differential effects suggest that the non-native host-symbiont pairing is sub-optimal with respect to the host's nutritional benefits under normal environmental conditions. This contributes to our understanding of the ways in which metabolic integration impacts the benefits of a symbiotic association, and the potential evolution of novel host-symbiont pairings. This article is protected by copyright. All rights reserved.

RevDate: 2020-06-25

Mateos M, Martinez Montoya H, Lanzavecchia SB, et al (2020)

Wolbachia pipientis Associated With Tephritid Fruit Fly Pests: From Basic Research to Applications.

Frontiers in microbiology, 11:1080.

Members of the true fruit flies (family Tephritidae) are among the most serious agricultural pests worldwide, whose control and management demands large and costly international efforts. The need for cost-effective and environmentally friendly integrated pest management (IPM) has led to the development and implementation of autocidal control strategies. These approaches include the widely used sterile insect technique and the incompatible insect technique (IIT). IIT relies on maternally transmitted bacteria (namely Wolbachia) to cause a conditional sterility in crosses between released mass-reared Wolbachia-infected males and wild females, which are either uninfected or infected with a different Wolbachia strain (i.e., cytoplasmic incompatibility; CI). Herein, we review the current state of knowledge on Wolbachia-tephritid interactions including infection prevalence in wild populations, phenotypic consequences, and their impact on life history traits. Numerous pest tephritid species are reported to harbor Wolbachia infections, with a subset exhibiting high prevalence. The phenotypic effects of Wolbachia have been assessed in very few tephritid species, due in part to the difficulty of manipulating Wolbachia infection (removal or transinfection). Based on recent methodological advances (high-throughput DNA sequencing) and breakthroughs concerning the mechanistic basis of CI, we suggest research avenues that could accelerate generation of necessary knowledge for the potential use of Wolbachia-based IIT in area-wide integrated pest management (AW-IPM) strategies for the population control of tephritid pests.

RevDate: 2020-06-25

Mannella CA (2020)

Consequences of Folding the Mitochondrial Inner Membrane.

Frontiers in physiology, 11:536.

A fundamental first step in the evolution of eukaryotes was infolding of the chemiosmotic membrane of the endosymbiont. This allowed the proto-eukaryote to amplify ATP generation while constraining the volume dedicated to energy production. In mitochondria, folding of the inner membrane has evolved into a highly regulated process that creates specialized compartments (cristae) tuned to optimize function. Internalizing the inner membrane also presents complications in terms of generating the folds and maintaining mitochondrial integrity in response to stresses. This review describes mechanisms that have evolved to regulate inner membrane topology and either preserve or (when appropriate) rupture the outer membrane.

RevDate: 2020-06-24

Miller JW, Bocke CR, Tresslar AR, et al (2020)

Paraburkholderia Symbionts Display Variable Infection Patterns That Are Not Predictive of Amoeba Host Outcomes.

Genes, 11(6): pii:genes11060674.

Symbiotic interactions exist within a parasitism to mutualism continuum that is influenced, among others, by genes and context. Dynamics of intracellular invasion, replication, and prevalence may underscore both host survivability and symbiont stability. More infectious symbionts might exert higher corresponding costs to hosts, which could ultimately disadvantage both partners. Here, we quantify infection patterns of diverse Paraburkholderia symbiont genotypes in their amoeba host Dictyostelium discoideum and probe the relationship between these patterns and host outcomes. We exposed D. discoideum to thirteen strains of Paraburkholderia each belonging to one of the three symbiont species found to naturally infect D. discoideum: Paraburkholderia agricolaris, Paraburkholderia hayleyella, and Paraburkholderia bonniea. We quantified the infection prevalence and intracellular density of fluorescently labeled symbionts along with the final host population size using flow cytometry and confocal microscopy. We find that infection phenotypes vary across symbiont strains. Symbionts belonging to the same species generally display similar infection patterns but are interestingly distinct when it comes to host outcomes. This results in final infection loads that do not strongly correlate to final host outcomes, suggesting other genetic factors that are not a direct cause or consequence of symbiont abundance impact host fitness.

RevDate: 2020-06-23

Lucek K, Butlin R, T Patsiou (2020)

Narrow phenotypic and parasitic clines shape secondary contact zones of closely-related Erebia butterflies.

Journal of evolutionary biology [Epub ahead of print].

Zones of secondary contact between closely related taxa are a common legacy of the Quaternary ice ages. Despite their abundance, the factors that keep species apart and prevent hybridisation are often unknown. Here we study a very narrow contact zone between three closely related butterfly species of the Erebia tyndarus species complex. Using genomic data, we first determined if gene flow occurs and then assessed whether it might be hampered by differences in chromosome number between some species. We found interspecific gene flow between sibling species that differ in karyotype by one chromosome. Conversely, only F1 hybrids occurred between two species that have the same karyotype, forming a steep genomic cline. In a second step, we fitted clines to phenotypic, ecological and parasitic data to identify the factors associated with the genetic cline. We found clines for phenotypic data and the prevalence of the endosymbiont parasite Wolbachia to overlap with the genetic cline, suggesting that they might be drivers for separating the two species. Overall our results highlight that some gene flow is possible between closely-related species despite different chromosome numbers, but that other barriers restrict such gene flow.

RevDate: 2020-06-19

Bagnaresi P, L Cattivelli (2020)

Ab initio GO-based mining for non-tandem-duplicated functional clusters in three model plant diploid genomes.

PloS one, 15(6):e0234782 pii:PONE-D-20-09184.

A functional Non-Tandem Duplicated Cluster (FNTDC) is a group of non-tandem-duplicated genes that are located closer than expected by mere chance and have a role in the same biological function. The identification of secondary-compounds-related FNTDC has gained increased interest in recent years, but little ab-initio attempts aiming to the identification of FNTDCs covering all biological functions, including primary metabolism compounds, have been carried out. We report an extensive FNTDC dataset accompanied by a detailed assessment on parameters used for genome scanning and their impact on FNTDC detection. We propose 70% identity and 70% alignment coverage as intermediate settings to exclude tandem duplicated genes and a dynamic scanning window of 24 genes. These settings were applied to rice, arabidopsis and grapevine genomes to call for FNTDCs. Besides the best-known secondary metabolism clusters, we identified many FNTDCs associated to primary metabolism ranging from macromolecules synthesis/editing, TOR signalling, ubiquitination, proton and electron transfer complexes. Using the intermediate FNTDC setting parameters (at P-value 1e-6), 130, 70 and 140 candidate FNTDCs were called in rice, arabidopsis and grapevine, respectively, and 20 to 30% of GO tags associated to called FNTDC were common among the 3 genomes. The datasets developed along with this work provide a rich framework for pinpointing candidate FNTDCs reflecting all GO-BP tags covering both primary and secondary metabolism with large macromolecular complexes/metabolons as the most represented FNTDCs. Noteworthy, several FNTDCs are tagged with GOs referring to organelle-targeted multi-enzyme complex, a finding that suggest the migration of endosymbiont gene chunks towards nuclei could be at the basis of these class of candidate FNTDCs. Most FNTDC appear to have evolved prior of genome duplication events. More than one-third of genes interspersed/adjacent to called FNTDCs lacked any functional annotation; however, their co-localization may provide hints towards a candidate biological role.

RevDate: 2020-06-19

Bhattacharya T, Newton ILG, RW Hardy (2020)

Viral RNA is a target for Wolbachia-mediated pathogen blocking.

PLoS pathogens, 16(6):e1008513 pii:PPATHOGENS-D-20-00601 [Epub ahead of print].

The ability of the endosymbiont Wolbachia pipientis to restrict RNA viruses is presently being leveraged to curb global transmission of arbovirus-induced diseases. Past studies have shown that virus replication is limited early in arthropod cells colonized by the bacterium, although it is unclear if this phenomenon is replicated in mosquito cells that first encounter viruses obtained through a vertebrate blood meal. Furthermore, these cellular events neither explain how Wolbachia limits dissemination of viruses between mosquito tissues, nor how it prevents transmission of infectious viruses from mosquitoes to vertebrate host. In this study, we try to address these issues using an array of mosquito cell culture models, with an additional goal being to identify a common viral target for pathogen blocking. Our results establish the viral RNA as a cellular target for Wolbachia-mediated inhibition, with the incoming viral RNA experiencing rapid turnover following internalization in cells. This early block in replication in mosquito cells initially infected by the virus thus consequently reduces the production of progeny viruses from these same cells. However, this is not the only contributor to pathogen blocking. We show that the presence of Wolbachia reduces the per-particle infectivity of progeny viruses on naïve mosquito and vertebrate cells, consequently limiting virus dissemination and transmission, respectively. Importantly, we demonstrate that this aspect of pathogen blocking is independent of any particular Wolbachia-host association and affects viruses belonging to Togaviridae and Flaviviridae families of RNA viruses. Finally, consistent with the idea of the viral RNA as a target, we find that the encapsidated virion RNA is less infectious for viruses produced from Wolbachia-colonized cells. Collectively, our findings present a common mechanism of pathogen blocking in mosquitoes that establish a link between virus inhibition in the cell to virus dissemination and transmission.

RevDate: 2020-06-17

Pirritano M, Zaburannyi N, Grosser K, et al (2020)

Dual-Seq reveals genome and transcriptome of Caedibacter taeniospiralis, obligate endosymbiont of Paramecium.

Scientific reports, 10(1):9727 pii:10.1038/s41598-020-65894-1.

Interest in host-symbiont interactions is continuously increasing, not only due to the growing recognition of the importance of microbiomes. Starting with the detection and description of novel symbionts, attention moves to the molecular consequences and innovations of symbioses. However, molecular analysis requires genomic data which is difficult to obtain from obligate intracellular and uncultivated bacteria. We report the identification of the Caedibacter genome, an obligate symbiont of the ciliate Paramecium. The infection does not only confer the host with the ability to kill other cells but also renders them immune against this effect. We obtained the C. taeniospiralis genome and transcriptome by dual-Seq of DNA and RNA from infected paramecia. Comparison of codon usage and expression level indicates that genes necessary for a specific trait of this symbiosis, i.e. the delivery of an unknown toxin, result from horizontal gene transfer hinting to the relevance of DNA transfer for acquiring new characters. Prediction of secreted proteins of Caedibacter as major agents of contact with the host implies, next to several toxin candidates, a rather uncharacterized secretome which appears to be highly adapted to this symbiosis. Our data provides new insights into the molecular establishment and evolution of this obligate symbiosis and for the pathway characterization of toxicity and immunity.

RevDate: 2020-06-16

Hall RJ, Thorpe S, Thomas GH, et al (2020)

Simulating the evolutionary trajectories of metabolic pathways for insect symbionts in the genus Sodalis.

Microbial genomics [Epub ahead of print].

Insect-bacterial symbioses are ubiquitous, but there is still much to uncover about how these relationships establish, persist and evolve. The tsetse endosymbiont Sodalis glossinidius displays intriguing metabolic adaptations to its microenvironment, but the process by which this relationship evolved remains to be elucidated. The recent chance discovery of the free-living species of the genus Sodalis, Sodalis praecaptivus, provides a serendipitous starting point from which to investigate the evolution of this symbiosis. Here, we present a flux balance model for S. praecaptivus and empirically verify its predictions. Metabolic modelling is used in combination with a multi-objective evolutionary algorithm to explore the trajectories that S. glossinidius may have undertaken from this starting point after becoming internalized. The order in which key genes are lost is shown to influence the evolved populations, providing possible targets for future in vitro genetic manipulation. This method provides a detailed perspective on possible evolutionary trajectories for S. glossinidius in this fundamental process of evolutionary and ecological change.

RevDate: 2020-06-11

Cornwell BH (2020)

Gene flow in the anemone Anthopleura elegantissima limits signatures of local adaptation across an extensive geographic range.

Molecular ecology [Epub ahead of print].

Species inhabiting marine environments face a wide range of environmental conditions that vary spatially across several orders of magnitude. The selective pressures that these conditions impose on marine organisms, in combination with potentially high rates of gene flow between distant populations, make it difficult to predict the extent to which these populations can locally adapt. Here, I identify how selection and gene flow influence the population genetic structure of the anemone Anthopleura elegantissima along the Pacific coast of North America. Isolation-by-distance is the dominant pattern across the range of this species, with a genetic break near Pt. Conception, CA. Furthermore, demographic modeling suggests that this species was historically confined to southerly latitudes before expanding northward. Outlier analyses identify 24 loci under selection (out of ~1,100), but the same analysis on simulated genetic data generated using the most likely demographic model erroneously identified the same number of loci under selection, if not more. Taken together, these results suggest that demographic processes are the dominant force shaping population genetic patterns in A. elegantissima along the Pacific coast of North America. I discuss these patterns in terms of the evolutionary history of A. elegantissima, the potential for local adaptation, and their consequences with respect to interactions with the endosymbiont Breviolum muscatinei across their geographic range.

RevDate: 2020-06-11

Madhav M, Brown G, Morgan JAT, et al (2020)

Transinfection of buffalo flies (Haematobia irritans exigua) with Wolbachia and effect on host biology.

Parasites & vectors, 13(1):296 pii:10.1186/s13071-020-04161-8.

BACKGROUND: Buffalo flies (Haematobia irritans exigua) (BF) and closely related horn flies (Haematobia irritans irritans) (HF) are invasive haematophagous parasites with significant economic and welfare impacts on cattle production. Wolbachia are intracellular bacteria found widely in insects and currently of much interest for use in novel strategies for the area wide control of insect pests and insect-vectored diseases. In this paper, we report the transinfection of BF towards the development of area-wide controls.

METHODS: Three stages of BF; embryos, pupae and adult female flies, were injected with different Wolbachia strains (wAlbB, wMel and wMelPop). The success of transinfection and infection dynamics was compared by real-time PCR and FISH and fitness effects were assessed in transinfected flies.

RESULTS: BF eggs were not easily injected because of their tough outer chorion and embryos were frequently damaged with less than 1% hatch rate of microinjected eggs. No Wolbachia infection was recorded in flies successfully reared from injected eggs. Adult and pupal injection resulted in higher survival rates and somatic and germinal tissue infections, with transmission to the succeeding generations on some occasions. Investigations of infection dynamics in flies from injected pupae confirmed that Wolbachia were actively multiplying in somatic tissues. Ovarian infections were confirmed with wMel and wMelPop in a number of instances, though not with wAlbB. Measurement of fitness traits indicated reduced longevity, decreased and delayed adult emergence, and reduced fecundity in Wolbachia-infected flies compared to mock-injected flies. Effects varied with the Wolbachia strain injected with most marked changes seen in the wMelPop-injected flies and least severe effects seen with wAlbB.

CONCLUSIONS: Adult and pupal injection were the most suitable methods for transinfecting BF and all three strains of Wolbachia successfully replicated in somatic tissues. The Wolbachia-induced fitness effects seen in transinfected BF suggest potential for use of the wMel or wMelPop strains in Wolbachia-based biocontrol programmes for BF.

RevDate: 2020-06-10

Bigiotti G, Sacchetti P, Pastorelli R, et al (2020)

Bacterial symbiosis in Bactrocera oleae, an Achilles' heel for its pest control.

Insect science [Epub ahead of print].

Investigations on microbial symbioses in Tephritidae have increased over the past 30 years owing to the potential use of these relationships in developing new control strategies for economically important fruit flies. Bactrocera oleae (Rossi)-the olive fruit fly-is a monophagous species strictly associated with the olive tree, and among all the tephritids, its symbionts are the most investigated. The bacterium Candidatus Erwinia dacicola is the major persistent resident endosymbiont in wild B. oleae populations. Its relationship with B. oleae has been investigated since being identified in 2005. This endosymbiont is vertically transmitted through generations from the female to the egg. It exists at every developmental stage, although it is more abundant in larvae and ovipositing females, and is necessary for both larvae and adults. Studying B. oleae-Ca. E. dacicola, or other B. oleae-microbe interactions, will allow us to develop modern biological control systems for area-wide olive protection and set an example for similar programs in other important food crops. This review summarizes the information available on tephritid-microbe interactions and investigates relationships among fruit flies, bacteria and host plants; however, its focus is on B. oleae and its strict association with Ca. E. dacicola to promote environmentally friendly control strategies for area-wide pest management. This article is protected by copyright. All rights reserved.

RevDate: 2020-06-05

Carretón E, Morchón R, Falcón-Cordón Y, et al (2020)

Evaluation of different dosages of doxycycline during the adulticide treatment of heartworm (Dirofilaria immitis) in dogs.

Veterinary parasitology, 283:109141 pii:S0304-4017(20)30121-7 [Epub ahead of print].

The endosymbiont bacteria Wolbachia plays an important role in the pathogenesis and inflammatory immune response to heartworm (Dirofilaria immitis) infection in dogs. Doxycycline is used to reduce Wolbachia from all life stages of heartworm to avoid large releases of the bacteria during the death of the worms. However, the dose and duration currently recommended have been extrapolated from the treatment of other rickettsial infections. Therefore, the aim was to study the dynamics of Wolbachia IgG antibodies in heartworm-infected dogs under adulticide treatment using different dosages of doxycycline. Forty-nine heartworm-infected dogs were recruited. On day 0 (diagnosis), monthly ivermectin (6 μg/kg) was prescribed, as well as daily doxycycline for 30 days, at 10 mg/kg/12 h (n = 13), 5 mg/kg/12 h (n = 19), and 10 mg/kg/24 h (n = 17). Dogs underwent adulticide treatment and blood samples were collected on days 0, 30, 90, and 120. All dogs had antibodies against recombinant Wolbachia surface protein (rWSP), confirming the important role of the bacteria in heartworm. No significant differences were found in anti-rWSP response by presence/absence of microfilariae, or by parasite burden on day 0. In all treated groups, the anti-rWSP antibody response was not significantly different between days 0 and 30 but was significantly lower between days 0 and 120 (p < 0.05). The results of the present study suggest that the administration of a lower dose than currently recommended is sufficient to achieve a significant reduction of Wolbachia in dogs infected by D. immitis.

RevDate: 2020-06-04

McCabe RA, Receveur JP, Houtz JL, et al (2020)

Characterizing the microbiome of ectoparasitic louse flies feeding on migratory raptors.

PloS one, 15(6):e0234050 pii:PONE-D-20-00922.

Louse flies (Diptera: Hippoboscidae) are obligate ectoparasites that often cause behavioral, pathogenic, and evolutionary effects on their hosts. Interactions between ectoparasites and avian hosts, especially migrating taxa, may influence avian pathogen spread in tropical and temperate ecosystems and affect long-term survival, fitness and reproductive success. The purpose of this study was to characterize the vector-associated microbiome of ectoparasitic louse flies feeding on migrating raptors over the fall migration period. Surveys for louse flies occurred during fall migration (2015-2016) at a banding station in Pennsylvania, United States; flies were collected from seven species of migrating raptors, and we sequenced their microbial (bacteria and archaea) composition using high-throughput targeted amplicon sequencing of the 16S rRNA gene (V4 region). All louse flies collected belonged to the same species, Icosta americana. Our analysis revealed no difference in bacterial communities of louse flies retrieved from different avian host species. The louse fly microbiome was dominated by a primary endosymbiont, suggesting that louse flies maintain a core microbial structure despite receiving blood meals from different host species. Thus, our findings highlight the importance of characterizing both beneficial and potentially pathogenic endosymbionts when interpreting how vector-associated microbiomes may impact insect vectors and their avian hosts.

RevDate: 2020-06-04

Singh KS, Troczka BJ, Duarte A, et al (2020)

The genetic architecture of a host shift: An adaptive walk protected an aphid and its endosymbiont from plant chemical defenses.

Science advances, 6(19):eaba1070 pii:aba1070.

Host shifts can lead to ecological speciation and the emergence of new pests and pathogens. However, the mutational events that facilitate the exploitation of novel hosts are poorly understood. Here, we characterize an adaptive walk underpinning the host shift of the aphid Myzus persicae to tobacco, including evolution of mechanisms that overcame tobacco chemical defenses. A series of mutational events added as many as 1.5 million nucleotides to the genome of the tobacco-adapted subspecies, M. p. nicotianae, and yielded profound increases in expression of an enzyme that efficiently detoxifies nicotine, both in aphid gut tissue and in the bacteriocytes housing the obligate aphid symbiont Buchnera aphidicola. This dual evolutionary solution overcame the challenge of preserving fitness of a mutualistic symbiosis during adaptation to a toxic novel host. Our results reveal the intricate processes by which genetic novelty can arise and drive the evolution of key innovations required for ecological adaptation.

RevDate: 2020-06-03

Adams M, McBroome J, Maurer N, et al (2020)

One fly-one genome: chromosome-scale genome assembly of a single outbred Drosophila melanogaster.

Nucleic acids research pii:5850803 [Epub ahead of print].

A high quality genome assembly is a vital first step for the study of an organism. Recent advances in technology have made the creation of high quality chromosome scale assemblies feasible and low cost. However, the amount of input DNA needed for an assembly project can be a limiting factor for small organisms or precious samples. Here we demonstrate the feasibility of creating a chromosome scale assembly using a hybrid method for a low input sample, a single outbred Drosophila melanogaster. Our approach combines an Illumina shotgun library, Oxford nanopore long reads, and chromosome conformation capture for long range scaffolding. This single fly genome assembly has a N50 of 26 Mb, a length that encompasses entire chromosome arms, contains 95% of expected single copy orthologs, and a nearly complete assembly of this individual's Wolbachia endosymbiont. The methods described here enable the accurate and complete assembly of genomes from small, field collected organisms as well as precious clinical samples.

RevDate: 2020-06-03

Luévano-Martínez LA, AL Duncan (2020)

Origin and diversification of the cardiolipin biosynthetic pathway in the Eukarya domain.

Biochemical Society transactions pii:225126 [Epub ahead of print].

Cardiolipin (CL) and its precursor phosphatidylglycerol (PG) are important anionic phospholipids widely distributed throughout all domains of life. They have key roles in several cellular processes by shaping membranes and modulating the activity of the proteins inserted into those membranes. They are synthesized by two main pathways, the so-called eukaryotic pathway, exclusively found in mitochondria, and the prokaryotic pathway, present in most bacteria and archaea. In the prokaryotic pathway, the first and the third reactions are catalyzed by phosphatidylglycerol phosphate synthase (Pgps) belonging to the transferase family and cardiolipin synthase (Cls) belonging to the hydrolase family, while in the eukaryotic pathway, those same reactions are catalyzed by unrelated homonymous enzymes: Pgps of the hydrolase family and Cls of the transferase family. Because of the enzymatic arrangement found in both pathways, it seems that the eukaryotic pathway evolved by convergence to the prokaryotic pathway. However, since mitochondria evolved from a bacterial endosymbiont, it would suggest that the eukaryotic pathway arose from the prokaryotic pathway. In this review, it is proposed that the eukaryote pathway evolved directly from a prokaryotic pathway by the neofunctionalization of the bacterial enzymes. Moreover, after the eukaryotic radiation, this pathway was reshaped by horizontal gene transfers or subsequent endosymbiotic processes.

RevDate: 2020-06-03

Zélé F, Altıntaş M, Santos I, et al (2020)

Population-specific effect of Wolbachia on the cost of fungal infection in spider mites.

Ecology and evolution, 10(9):3868-3880 pii:ECE36015.

Many studies have revealed the ability of the endosymbiotic bacterium Wolbachia to protect its arthropod hosts against diverse pathogens. However, as Wolbachia may also increase the susceptibility of its host to infection, predicting the outcome of a particular Wolbachia-host-pathogen interaction remains elusive. Yet, understanding such interactions and their eco-evolutionary consequences is crucial for disease and pest control strategies. Moreover, how natural Wolbachia infections affect artificially introduced pathogens for biocontrol has never been studied. Tetranychus urticae spider mites are herbivorous crop pests, causing severe damage on numerous economically important crops. Due to the rapid evolution of pesticide resistance, biological control strategies using entomopathogenic fungi are being developed. However, although spider mites are infected with various Wolbachia strains worldwide, whether this endosymbiont protects them from fungi is as yet unknown. Here, we compared the survival of two populations, treated with antibiotics or naturally harboring different Wolbachia strains, after exposure to the fungal biocontrol agents Metarhizium brunneum and Beauveria bassiana. To control for potential effects of the bacterial community of spider mites, we also compared the susceptibility of two populations naturally uninfected by Wolbachia, treated with antibiotics or not. In one population, Wolbachia-infected mites had a better survival than uninfected ones in absence of fungi but not in their presence, whereas in the other population Wolbachia increased the mortality induced by B. bassiana. In one naturally Wolbachia-uninfected population, the antibiotic treatment increased the susceptibility of spider mites to M. brunneum, but it had no effect in the other treatments. These results suggest that natural Wolbachia infections may not hamper and may even improve the success of biological control using entomopathogenic fungi. However, they also draw caution on the generalization of such effects, given the complexity of within-host-pathogens interaction and the potential eco-evolutionary consequences of the use of biocontrol agents for Wolbachia-host associations.

RevDate: 2020-06-01

Mazzucco R, Nolte V, Vijayan T, et al (2020)

Long-Term Dynamics Among Wolbachia Strains During Thermal Adaptation of Their Drosophila melanogaster Hosts.

Frontiers in genetics, 11:482.

Climate change is a major evolutionary force triggering thermal adaptation in a broad range of species. While the consequences of global warming are being studied for an increasing number of species, limited attention has been given to the evolutionary dynamics of endosymbionts in response to climate change. Here, we address this question by studying the dynamics of Wolbachia, a well-studied endosymbiont of Drosophila melanogaster. D. melanogaster populations infected with 13 different Wolbachia strains were exposed to novel hot and cold laboratory environments for up to 180 generations. The short-term dynamics suggested a temperature-related fitness difference resulting in the increase of clade V strains in the cold environment only. Our long-term analysis now uncovers that clade V dominates in all replicates after generation 60 irrespective of temperature treatment. We propose that adaptation of the Drosophila host to either temperature or Drosophila C virus (DCV) infection are the cause of the replicated, temporally non-concordant Wolbachia dynamics. Our study provides an interesting case demonstrating that even simple, well-controlled experiments can result in complex, but repeatable evolutionary dynamics, thus providing a cautionary note on too simple interpretations on the impact of climate change.

RevDate: 2020-05-29

Shah SHJ, Malik AH, Zhang B, et al (2020)

Metagenomic analysis of relative abundance and diversity of bacterial microbiota in Bemisia tabaci infesting cotton crop in Pakistan.

Infection, genetics and evolution : journal of molecular epidemiology and evolutionary genetics in infectious diseases pii:S1567-1348(20)30212-4 [Epub ahead of print].

B. tabaci species complex are among the world's most devastating agricultural pests causing economic losses by direct feeding and more importantly by transmitting plant viruses like cotton leaf curl disease (CLCuD) associated viruses to cultivated cotton in Pakistan. Taxonomic diversity of B. tabaci associated bacterial communities using NGS techniques so far is reported from insects grown on artificial diet under lab conditions. In this study 16S rDNA metagenome sequencing analysis was used to characterize bacterial compositions in wild adult B. tabaci infesting cultivated cotton in eight major cotton growing districts of southern Punjab, Pakistan. We have identified 50 known and 7 unknown genera of bacteria belonging to 10 phyla, 20 classes, 30 orders and 40 families. Beta diversity analysis of our data sets reveal that whiteflies infesting cotton in geographically distinct locations had similar bacterial diversity. These results for the first time provide insights into the microbiome diversity of wild type whiteflies infesting a cultivated crop.

RevDate: 2020-05-27

Guizzo MG, Neupane S, Kucera M, et al (2020)

Poor Unstable Midgut Microbiome of Hard Ticks Contrasts With Abundant and Stable Monospecific Microbiome in Ovaries.

Frontiers in cellular and infection microbiology, 10:211.

Culture-independent metagenomic methodologies have enabled detection and identification of microorganisms in various biological systems and often revealed complex and unknown microbiomes. In many organisms, the microbiome outnumbers the host cells and greatly affects the host biology and fitness. Ticks are hematophagous ectoparasites with a wide host range. They vector a number of human and animal pathogens and also directly cause major economic losses in livestock. Although several reports on a tick midgut microbiota show a diverse bacterial community, in most cases the size of the bacterial population has not been determined. In this study, the microbiome was quantified in the midgut and ovaries of the ticks Ixodes ricinus and Rhipicephalus microplus before, during, and after blood feeding. Although the size of bacterial community in the midgut fluctuated with blood feeding, it was overall extremely low in comparison to that of other hematophagous arthropods. In addition, the tick ovarian microbiome of both tick species exceeded the midgut 16S rDNA copy numbers by several orders of magnitude. This indicates that the ratio of a tick midgut/ovary microbiome represents an exception to the general biology of other metazoans. In addition to the very low abundance, the tick midgut diversity in I. ricinus was variable and that is in contrast to that found in the tick ovary. The ovary of I. ricinus had a very low bacterial diversity and a very high and stable bacterial abundance with the dominant endosymbiont, Midichloria sp. The elucidation of this aspect of tick biology highlights a unique tissue-specific microbial-invertebrate host interaction.

RevDate: 2020-05-27

Laidoudi Y, Marie JL, Tahir D, et al (2020)

Detection of Canine Vector-Borne Filariasis and Their Wolbachia Endosymbionts in French Guiana.

Microorganisms, 8(5): pii:microorganisms8050770.

In French Guiana, canine heartworm disease is well known, but the diversity of filarial parasites of dogs remains largely unknown. A total of 98 canine blood samples from Cayenne and Kourou were assessed by a blood wet mount preparation, heartworm antigen test and molecular exploration of filarioid and Wolbachia DNAs, followed by a multiplex species-specific qPCR's identification and a subsequent sequencing analysis. Thereafter, a phylogeny based on maximum likelihood was carried out to facilitate specific identification. Five dogs were microfilaremic. Heartworm antigens were detected in 15 (15.3%) dogs. Of these, six (6.1%) were considered as occult infections as neither microfilariae nor Dirofilaria immitis DNA were detected. The 11 (11.2%) D. immitis isolates corresponded to a low virulent strain. Six of the D. immitis isolates were positive for Wolbachia endosymbionts of D. immitis belonging to the clade C DNA. Acanthocheilonema reconditum DNA was detected in 3 (3.1%) samples. Of these latter, one was found co-infected with the Brugia sp. genotype and the DNA of the clade D of the Wolbachia endosymbiont of Brugia species. This latter was also detected in two filarioid DNA-free samples. Finally, two samples were positive for Cercopithifilaria bainae genotype, which is distinct from those identified in Europe. The present study highlights the urgent need to implement chemoprophylaxis associated with anti-Wolbachia drugs to control these potential zoonoses.

RevDate: 2020-05-25

Li J, Kelly P, Guo W, et al (2020)

Molecular detection of Rickettsia, Hepatozoon, Ehrlichia and SFTSV in goat ticks.

Veterinary parasitology, regional studies and reports, 20:100407.

Ticks are vectors of various pathogens to people, livestock, companion animals and wildlife. We describe here the ticks found on goats in Anhui province of China and the results of molecular studies on six tick-borne pathogens they might harbor. Among 125 ticks collected (119 Haemaphysalis longicornis, n = 119; Rhipicephalus microplus, n = 6), we detected four of the six tick-borne agents for which we tested. In total, 16.8% of the H. longicornis were positive for Candidatus Rickettsia longicornii (18/119), Rickettsia endosymbiont of Leptocybe invasa (1/119) and Rickettsia sibirica (1/119). Hepatozoon canis was positive for 41.6% of the ticks (H. longicornis 42.0%, 50/119; R. microplus 12.5%, 2/6). Only 5.6% of the ticks were positive for Ehrlichia (H. longicornis 5.0%, 6/119; R. microplus 16.7%, 1/6). The Severe Fever with Thrombocytopenia Syndrome Virus was only identified in one H. longicornis. Such data is important in developing effective, integrated and strategic control measures for ticks and the pathogens they transmit.

RevDate: 2020-05-25

Sass K, Güllert S, Streit WR, et al (2020)

A hydrogen-oxidizing bacterium enriched from the open ocean resembling a symbiont.

Environmental microbiology reports [Epub ahead of print].

A new autotrophic hydrogen-oxidizing Chromatiaceae bacterium, namely bacterium CTD079, was enriched from a water column sample at 1500 m water depth in the southern Pacific Ocean. Based on the phylogeny of 16S rRNA genes, it was closely related to a scaly snail endosymbiont (99.2% DNA sequence identity) whose host so far is only known to colonize hydrothermal vents along the Indian ridge. The average nucleotide identity between the genomes of CTD079 and the snail endosymbiont was 91%. The observed differences likely reflect adaptations to their specific habitats. For example, CTD079 encodes additional enzymes like the formate dehydrogenase increasing the organism's spectrum of energy generation pathways. Other additional physiological features of CTD079 included the increase of viral defence strategies, secretion systems and specific transporters for essential elements. These important genome characteristics suggest an adaptation to life in the open ocean.

RevDate: 2020-05-23

Masson F, Schüpfer F, Jollivet C, et al (2020)

Transformation of the Drosophila sex-manipulative endosymbiont Spiroplasma poulsonii and persisting hurdles for functional genetics studies.

Applied and environmental microbiology pii:AEM.00835-20 [Epub ahead of print].

Insects are frequently infected by bacterial symbionts that greatly affect their physiology and ecology. Most of these endosymbionts are however barely tractable outside of their native host, rendering functional genetics studies difficult or impossible. Spiroplasma poulsonii is a facultative bacterial endosymbiont of Drosophila melanogaster that manipulates its host reproduction by killing its male progeny at the embryonic stage. S. poulsonii, although being a very fastidious bacteria, is closely related to pathogenic Spiroplasma species that are cultivable and genetically modifiable. In this work, we present the transformation of S. poulsonii with a plasmid bearing a fluorescence cassette, leveraging techniques adapted from those used to modify the pathogenic species S. citri. We demonstrate the feasibility of S. poulsonii transformation and discuss approaches for mutant selection and fly colonization, which are persisting hurdles that will need to be overcome to allow functional bacterial genetics studies of this endosymbiont in vivo.Importance Dozens of bacterial endosymbiont species are described and estimated to infect about the half of all insect species. Yet only a handful of them are tractable in vitro, which hampers the understanding of the bacterial determinants of the host-symbiont interaction. Developing a transformation method for S. poulsonii is a major step towards genomic engineering of this symbiont, which will foster basic research on endosymbiosis. This could also open the way to practical uses of endosymbiont engineering through paratransgenesis of vector or pest insects.

RevDate: 2020-05-23

Manzano-Marín A (2020)

No evidence for Wolbachia as a nutritional co-obligate endosymbiont in the aphid Pentalonia nigronervosa.

Microbiome, 8(1):72 pii:10.1186/s40168-020-00865-2.

Obligate symbiotic associations are present in a wide variety of animals with a nutrient-restricted diet. Aphids (hemiptera: Aphididae) almost-universally host Buchnera aphidicola bacteria in specialised organs (called bacteriomes). These bacteria supply the aphid with essential nutrients lacking from their diet (i.e. essential amino acids and some B vitamins). Some aphid lineages, such as species from the Lacninae subfamily, have evolved co-obligate associations with secondary endosymbionts, deriving from a loss of biotin- and riboflavin-biosynthetic genes. In this study, I re-analyse previously published sequencing data from the banana aphid Pentalonia nigronervosa. I show that the metabolic inference results from De Clerck et al. (Microbiome 3:63, 2015) are incorrect and possibly arise from the use of inadequate methods. Additionally, I discuss how the seemingly biased interpretation of their antibiotic treatment analyses together with an incorrect genome-based metabolic inference resulted in the erroneous suggestion "that a co-obligatory symbiosis between B. aphidicola and Wolbachia occurs in the banana aphid".

RevDate: 2020-05-21

Goñi P, Benito M, LaPlante D, et al (2020)

Identification of free-living amoebas and amoeba-resistant bacteria accumulated in Dreissena polymorpha.

Environmental microbiology [Epub ahead of print].

To identify the free-living amoeba (FLA) and amoeba resistant bacteria (ARB) accumulated in zebra mussels and in the water in which they are found, mussels were collected at two locations in the Ebro river basin (North East Spain). Free-living amoebas and bacteria were isolated from mussel extracts and from natural water. PCR techniques were used to identify the FLAs and endosymbiont bacteria (Legionella, Mycobacterium, Pseudomonas and cyanobacteria), and to detect Giardia and Cryptosporidium. The most frequently found FLAs were Naegleria spp. The presence of Legionella, Mycobacterium, and Pseudomonas inside the FLA was demonstrated, and in some cases both Legionella and Pseudomonas were found together. Differences between FLAs and ARB identified inside the mussels and in the water were detected. In addition, Escherichia coli, Clostridium perfringens, Salmonella spp. and Enterococcus spp. were accumulated in mussels in concentrations unconnected with those found in water. The results show the ability of the zebra mussel to act as a reservoir of potentially pathogenic FLAs, which are associated with potentially pathogenic amoeba-resistant bacteria, although the lack of association between microorganisms inside the mussels and in the water suggests that they are not useful for monitoring microbiological contamination at a specific time. This article is protected by copyright. All rights reserved.

RevDate: 2020-05-19

Lane N (2020)

How energy flow shapes cell evolution.

Current biology : CB, 30(10):R471-R476.

How mitochondria shaped the evolution of eukaryotic complexity has been controversial for decades. The discovery of the Asgard archaea, which harbor close phylogenetic ties to the eukaryotes, supports the idea that a critical endosymbiosis between an archaeal host and a bacterial endosymbiont transformed the selective constraints present at the origin of eukaryotes. Cultured Asgard archaea are typically prokaryotic in both size and internal morphology, albeit featuring extensive protrusions. The acquisition of the mitochondrial predecessor by an archaeal host cell fundamentally altered the topology of genes in relation to bioenergetic membranes. Mitochondria internalised not only the bioenergetic membranes but also the genetic machinery needed for local control of oxidative phosphorylation. Gene loss from mitochondria enabled expansion of the nuclear genome, giving rise to an extreme genomic asymmetry that is ancestral to all extant eukaryotes. This genomic restructuring gave eukaryotes thousands of fold more energy availability per gene. In principle, that difference can support more and larger genes, far more non-coding DNA, greater regulatory complexity, and thousands of fold more protein synthesis per gene. These changes released eukaryotes from the bioenergetic constraints on prokaryotes, facilitating the evolution of morphological complexity.

RevDate: 2020-05-19

Buerger P, Alvarez-Roa C, Coppin CW, et al (2020)

Heat-evolved microalgal symbionts increase coral bleaching tolerance.

Science advances, 6(20):eaba2498 pii:aba2498.

Coral reefs worldwide are suffering mass mortalities from marine heat waves. With the aim of enhancing coral bleaching tolerance, we evolved 10 clonal strains of a common coral microalgal endosymbiont at elevated temperatures (31°C) for 4 years in the laboratory. All 10 heat-evolved strains had expanded their thermal tolerance in vitro following laboratory evolution. After reintroduction into coral host larvae, 3 of the 10 heat-evolved endosymbionts also increased the holobionts' bleaching tolerance. Although lower levels of secreted reactive oxygen species (ROS) accompanied thermal tolerance of the heat-evolved algae, reduced ROS secretion alone did not predict thermal tolerance in symbiosis. The more tolerant symbiosis exhibited additional higher constitutive expression of algal carbon fixation genes and coral heat tolerance genes. These findings demonstrate that coral stock with enhanced climate resilience can be developed through ex hospite laboratory evolution of their microalgal endosymbionts.

RevDate: 2020-05-17

Bodnar J, Fitch S, Sanchez J, et al (2020)

GTP cyclohydrolase I activity from Rickettsia monacensis strain Humboldt, a rickettsial endosymbiont of Ixodes pacificus.

Ticks and tick-borne diseases pii:S1877-959X(19)30506-0 [Epub ahead of print].

The complete folate biosynthesis pathway exists in the genome of a rickettsial endosymbiont of Ixodes pacificus, Rickettsia monacensis strain Humboldt (formerly known as Rickettsia species phylotype G021). Recently, our lab demonstrated that the folA gene of strain Humboldt, the final gene in the folate biosynthesis pathway, encodes a functional dihydrofolate reductase enzyme. In this study, we report R. monacensis strain Humboldt has a functional GTP cyclohydrolase I (GCH1), an enzyme required for the hydrolysis of GTP to form 7,8-dihydroneopterin triphosphate in the folate biosynthesis pathway. The GCH1 gene of R. monacensis, folE, share homology with the folE gene of R. monacensis strain IrR/Munich, with a nucleotide sequence identity of 99%. Amino acid alignment and comparative protein structure modeling have shown that the FolE protein of R. monacensis has a conserved core subunit of GCH1 from the T-fold structural superfamily. All amino acid residues, including conserved GTP binding sites and zinc binding sites, are preserved in the FolE protein of R. monacensis. A recombinant GST-FolE protein from R. monacensis was overexpressed in Escherichia coli, purified by affinity chromatography, and assayed for enzyme activity in vitro. The in vitro enzymatic assay described in this study accorded the recombinant GCH1 enzyme of R. monacensis with a specific activity of 0.81 U/mg. Our data suggest folate genes of R. monacensis strain Humboldt have the potential to produce biochemically active enzymes for de novo folate synthesis, addressing the physioecological underpinnings behind tick-Rickettsia symbioses.

RevDate: 2020-05-13

Sibbald SJ, JM Archibald (2020)

Genomic insights into plastid evolution.

Genome biology and evolution pii:5836826 [Epub ahead of print].

The origin of plastids (chloroplasts) by endosymbiosis stands as one of the most important events in the history of eukaryotic life. The genetic, biochemical, and cell biological integration of a cyanobacterial endosymbiont into a heterotrophic host eukaryote more than a billion years ago paved the way for the evolution of diverse algal groups in a wide range of aquatic and, eventually, terrestrial environments. Plastids have on multiple occasions also moved horizontally from eukaryote to eukaryote by secondary and tertiary endosymbiotic events. The overall picture of extant photosynthetic diversity can best be described as 'patchy': plastid-bearing lineages are spread far and wide across the eukaryotic tree of life, nested within heterotrophic groups. The algae do not constitute a monophyletic entity and understanding how, and how often, plastids have moved from branch to branch on the eukaryotic tree remains one of the most fundamental unsolved problems in the field of cell evolution. In this review we provide an overview of recent advances in our understanding of the origin and spread of plastids from the perspective of comparative genomics. Recent years have seen significant improvements in genomic sampling from photosynthetic and non-photosynthetic lineages, both of which have provided important pieces to add to the puzzle of plastid evolution. Comparative genomics has also allowed us to better understand how endosymbionts become organelles.

RevDate: 2020-05-13

Ghosh S, Sela N, Kontsedalov S, et al (2020)

An Intranuclear Sodalis-Like Symbiont and Spiroplasma Coinfect the Carrot Psyllid, Bactericera trigonica (Hemiptera, Psylloidea).

Microorganisms, 8(5): pii:microorganisms8050692.

Endosymbionts harbored inside insects play critical roles in the biology of their insect host and can influence the transmission of pathogens by insect vectors. Bactericeratrigonica infests umbelliferous plants and transmits the bacterial plant pathogen Candidatus Liberibacter solanacearum (CLso), causing carrot yellows disease. To characterize the bacterial diversity of B. trigonica, as a first step, we used PCR-restriction fragment length polymorphism (PCR-RFLP) and denaturing gradient gel electrophoresis (DGGE) analyses of 16S rDNA to identify Sodalis and Spiroplasma endosymbionts. The prevalence of both symbionts in field-collected psyllid populations was determined: Sodalis was detected in 100% of field populations, while Spiroplasma was present in 82.5% of individuals. Phylogenetic analysis using 16S rDNA revealed that Sodalis infecting B. trigonica was more closely related to symbionts infecting weevils, stink bugs and tsetse flies than to those from psyllid species. Using fluorescent in situ hybridization and immunostaining, Sodalis was found to be localized inside the nuclei of the midgut cells and bacteriocytes. Spiroplasma was restricted to the cytoplasm of the midgut cells. We further show that a recently reported Bactericera trigonica densovirus (BtDNV), a densovirus infecting B. trigonica was detected in 100% of psyllids and has reduced titers inside CLso-infected psyllids by more than two-fold compared to CLso uninfected psyllids. The findings of this study will help to increase our understanding of psyllid-endosymbiont interactions.

RevDate: 2020-05-11

Kaur R, Martinez J, Rota-Stabelli O, et al (2020)

Age, tissue, genotype and virus infection regulate Wolbachia levels in Drosophila.

Molecular ecology [Epub ahead of print].

The bacterial symbiont Wolbachia can protect insects against viral pathogens, and the varying levels of antiviral protection are correlated with the endosymbiont load within the insects. To understand why Wolbachia strains differ in their antiviral effects, we investigated the factors controlling Wolbachia density in five closely related strains in their natural Drosophila hosts. We found that Wolbachia density varied greatly across different tissues and between flies of different ages, and these effects depended on the host-symbiont association. Some endosymbionts maintained largely stable densities as flies aged while others increased, and these effects in turn depended on the tissue being examined. Measuring Wolbachia rRNA levels in response to viral infection, we found that viral infection itself also altered Wolbachia levels, with FHV causing substantial reductions in symbiont loads late in the infection. This effect, however, was virus-specific as DCV had little impact on Wolbachia in all of the five host systems. Since viruses have strong tissue tropisms and antiviral protection is thought to be cell-autonomous, these effects are likely to affect the virus-blocking phenomenon. However, we were unable to find any evidence of a correlation between Wolbachia and viral titers within the same tissues. We conclude that Wolbachia levels within flies are regulated in a complex host-symbiont-virus dependent manner and this trinity is likely to influence the antiviral effects of Wolbachia.

RevDate: 2020-05-11

Ben-Yosef M, Rot A, Mahagna M, et al (2020)

Coxiella-Like Endosymbiont of Rhipicephalus sanguineus Is Required for Physiological Processes During Ontogeny.

Frontiers in microbiology, 11:493.

Obligatory hematophagous arthropods such as lice, bugs, flies, and ticks harbor bacterial endosymbionts that are expected to complement missing essential nutrients in their diet. Genomic and some experimental evidence support this expectation. Hard ticks (Acari: Ixodidae) are associated with several lineages of bacterial symbionts, and very few were experimentally shown to be essential to some aspects of tick's fitness. In order to pinpoint the nature of interactions between hard ticks and their symbionts, we tested the effect of massive elimination of Coxiella-like endosymbionts (CLE) by antibiotics on the development and fitness of the brown dog tick (Rhipicephalus sanguineus). Administration of ofloxacin to engorged (blood fed) nymphs resulted in significant and acute reduction of their CLE loads - an effect that also persisted in subsequent life stages (aposymbiotic ticks). As a result, the post-feeding development of aposymbiotic female (but not male) nymphs was delayed. Additionally, aposymbiotic adult females needed a significantly prolonged feeding period in order to replete (detach from host), and had reduced engorgement weight and a lower capacity to produce eggs. Consequently, their fecundity and fertility were significantly reduced. Eggs produced by aposymbiotic females were free of CLE, and the resulting aposymbiotic larvae were unable to feed successfully. Our findings demonstrate that the observed fitness effects are due to CLE reduction and not due to antibiotic administration. Additionally, we suggest that the contribution of CLE is not mandatory for oocyte development and embryogenesis, but is required during feeding in females, when blood meal processing and tissue buildup are taking place. Presumably, under these extreme physiological demands, CLE contribute to R. sanguineus through supplementing essential micro- and macronutrients. Further nutrient complementary studies are required to support this hypothesis.

RevDate: 2020-05-10

Zhu YX, Song ZR, Song YL, et al (2020)

Double infection of Wolbachia and Spiroplasma alters induced plant defense and spider mite fecundity.

Pest management science [Epub ahead of print].

BACKGROUND: Herbivore-associated bacterial symbionts can change plant physiology and influence the herbivore's fitness. The spider mite Tetranychus truncatus is a notorious pest harboring various bacterial symbionts, however, the effect of bacterial symbionts on host plant physiology remains unclear. Here, we investigated whether infection with the endosymbionts Wolbachia and Spiroplasma altered spider mite performance on particular tomato plants and affected the plant induced defenses.

RESULTS: Wolbachia and Spiroplasma were mainly located at the gnathosoma and ovaries of spider mite hosts. Wolbachia and Spiroplasma significantly improved spider mite reproductive performance in cultivated and wild-type tomato. However, in jasmonic acid (JA) and salicylic acid (SA)-deficient plants, there were no significant differences in the reproduction between Wolbachia and Spiroplasma-infected and uninfected spider mites. The results indicated that the reproduction benefits conferred by endosymbionts may relate to plant defenses. Both Wolbachia and Spiroplasma-infected and uninfected spider mites induced similar levels of JA and SA accumulation in tomato, whereas tomato plants damaged by Wolbachia and Spiroplasma-infected spider mites showed lower the expression levels of the JA and SA-responsive genes than those damaged by uninfected spider mites. Additionally, Wolbachia and Spiroplasma-infected mites consumed much tomato amino acid compared to uninfected spider mites, which may have contributed to host fecundity.

CONCLUSIONS: Our results suggest that the reproduction benefits conferred by endosymbionts may be associated with changes in plant defense parameters and the concentrations of plant amino acids. The results highlight the importance of endosymbionts in the interactions between spider mites and their host plants. This article is protected by copyright. All rights reserved.

RevDate: 2020-05-09

Rouïl J, Jousselin E, Coeur d'Acier A, et al (2020)

The protector within: Comparative genomics of APSE phages across aphids reveals rampant recombination and diverse toxin arsenals.

Genome biology and evolution pii:5835279 [Epub ahead of print].

Phages can fundamentally alter the physiology and metabolism of their hosts. While ubiquitous in the bacterial world, they have seldom been described among endosymbiotic bacteria. One notable exception in the APSE phage that is found associated with the gammaproteobacterial Hamiltonella defensa, hosted by several insect species. This secondary facultative endosymbiont is not necessary for the survival of its hosts but can infect certain individuals or even whole populations. Its infection in aphids is often associated with protection against parasitoid wasps. This protective phenotype has actually been linked to the infection of the symbiont strain with an APSE, which carries a toxin cassette that varies among so-called "types". In the present work, we seek to expand our understanding of the diversity of APSE phages as well as the relations of their Hamiltonella hosts. For this, we assembled and annotated the full genomes of 16 APSE phages infecting Hamiltonella symbionts across 10 insect species. Molecular and phylogenetic analyses suggest that recombination has occurred repeatedly among lineages. Comparative genomics of the phage genomes revealed two variable regions that are useful for phage typing. Additionally, we find that mobile elements could play a role in the acquisition of new genes in the toxin cassette. Altogether, we provide an unprecedented view of APSE diversity and their genome evolution across aphids. This genomic investigation will provide a valuable resource for the design and interpretation of experiments aiming at understanding the protective phenotype these phages confer to their insect hosts.

RevDate: 2020-05-02

Sinno M, Bézier A, Vinale F, et al (2020)

Symbiosis disruption in the olive fruit fly, Bactrocera oleae (Rossi), as a potential tool for sustainable control.

Pest management science [Epub ahead of print].

BACKGROUND: The olive fruit fly Bactrocera oleae (Rossi) (OLF) is a major agricultural pest, whose control primarily relies on the use of chemical insecticides. Therefore, the development of sustainable control strategies is highly desirable. The primary endosymbiotic bacterium of the OLF, "Candidatus Erwinia dacicola", is essential for successful larval development in unripe olive fruits. Then, targeting this endosymbiont with antimicrobial compounds may result in OLF fitness reduction and may exert a control action of its natural populations.

RESULTS: Here we evaluate the impact of compounds with antimicrobial activity on OLF endosymbiont. Copper Oxychloride (CO) and the fungal metabolite Viridiol (Vi), produced by Trichoderma spp., were used. Laboratory bioassays were carried out to assess the effect of the oral administration of these compounds on OLF fitness and molecular analyses (qPCR) were conducted to measure the load of OLF-associated microorganisms in treated flies. CO and Vi were both able to disrupt the symbiotic association between OLF and its symbiotic bacteria, determining a significant reduction of the endosymbiont and gut microbiota load as well as an OLF fitness decrease. CO had a direct negative effect on OLF adults. Conversely, exposure to Vi significantly undermined the larval development of the treated females' progeny but did not show any toxicity in OLF adults.

CONCLUSIONS: These results provide new insights on the symbiotic control of the OLF and pave the way toward the development of more sustainable strategies of pest control based on the use of natural compounds with antimicrobial activity. This article is protected by copyright. All rights reserved.

RevDate: 2020-04-30

Modeo L, Salvetti A, Rossi L, et al (2020)

"Candidatus Trichorickettsia mobilis", a Rickettsiales bacterium, can be transiently transferred from the unicellular eukaryote Paramecium to the planarian Dugesia japonica.

PeerJ, 8:e8977 pii:8977.

Most of the microorganisms responsible for vector-borne diseases (VBD) have hematophagous arthropods as vector/reservoir. Recently, many new species of microorganisms phylogenetically related to agents of VBD were found in a variety of aquatic eukaryotic hosts; in particular, numerous new bacterial species related to the genus Rickettsia (Alphaproteobacteria, Rickettsiales) were discovered in protist ciliates and other unicellular eukaryotes. Although their pathogenicity for humans and terrestrial animals is not known, several indirect indications exist that these bacteria might act as etiological agents of possible VBD of aquatic organisms, with protists as vectors. In the present study, a novel strain of the Rickettsia-Like Organism (RLO) endosymbiont "Candidatus (Ca.) Trichorickettsia mobilis" was identified in the macronucleus of the ciliate Paramecium multimicronucleatum. We performed transfection experiments of this RLO to planarians (Dugesia japonica) per os. Indeed, the latter is a widely used model system for studying bacteria pathogenic to humans and other Metazoa. In transfection experiments, homogenized paramecia were added to food of antibiotic-treated planarians. Treated and non-treated (i.e. control) planarians were investigated at day 1, 3, and 7 after feeding for endosymbiont presence by means of PCR and ultrastructural analyses. Obtained results were fully concordant and suggest that this RLO endosymbiont can be transiently transferred from ciliates to metazoans, being detected up to day 7 in treated planarians' enterocytes. Our findings might offer insights into the potential role of ciliates or other protists as putative vectors for diseases caused by Rickettsiales or other RLOs and occurring in fish farms or in the wild.

RevDate: 2020-04-30

Ganyukova AI, Frolov AO, Malysheva MN, et al (2020)

A novel endosymbiont-containing trypanosomatid Phytomonas borealis sp. n. from the predatory bug Picromerus bidens (Heteroptera: Pentatomidae).

Folia parasitologica, 67:.

Here we describe the new trypanosomatid, Phytomonas borealis sp. n., from the midgut of the spiked shieldbugs, Picromerus bidens (Linnaeus), collected in two locations, Novgorod and Pskov Oblasts of Russia. The phylogenetic analyses, based on the 18S rRNA gene, demonstrated that this flagellate is a sister species to the secondary monoxenous Phytomonas nordicus Frolov et Malysheva, 1993, which was concurrently documented in the same host species in Pskov Oblast. Unlike P. nordicus, which can complete its development (including exit to haemolymph and penetration into salivary glands) in Picromerus bidens, the new species did not form any extraintestinal stages in the host. It also did not produce endomastigotes, indispensable for transmission in other Phytomonas spp. These observations, along with the fact that P. bidens overwinters at the egg stage, led us to the conclusion that the examined infections with P. borealis were non-specific. Strikingly, the flagellates from the Novgorod population contained prokaryotic endosymbionts, whereas the parasites from the second locality were endosymbiont-free. This is a first case documenting presence of intracellular symbiotic bacteria in Phytomonas spp. We suggest that this novel endosymbiotic association arose very recently and did not become obligate yet. Further investigation of P. borealis and its intracellular bacteria may shed light on the origin and early evolution of endosymbiosis in trypanosomatids.

RevDate: 2020-04-27

Lv N, Peng J, Chen XY, et al (2020)

Antagonistic interaction between male-killing and cytoplasmic incompatibility induced by Cardinium and Wolbachia in the whitefly, Bemisia tabaci.

Insect science [Epub ahead of print].

Cardinium and Wolbachia are maternally inherited bacterial symbionts of arthropods that can manipulate host reproduction by increasing the fitness of infected females. Here, we report that Cardinium and Wolbachia coinfection induced male-killing and cytoplasmic incompatibility (CI) when they coexisted in a cryptic species of whitefly, Bemisia tabaci Asia II7. Cardinium and Wolbachia symbionts were either singly or simultaneously localized in the bacteriocytes placed in the abdomen of B. tabaci nymphs and adults. Cardinium-Wolbachia coinfection induced male-killing and resulted in a higher female sex ratio in the intraspecific amphigenetic progeny of Asia II7 ICWH and ICWL lines; interestingly, male-killing induction was enhanced with increased Cardinium titer. Moreover, single infection of Wolbachia induced partial CI in the Asia II7 IW line and resulted in reduced fecundity, higher embryonic mortality, and lower female sex ratio. The uninfected Asia II7 IU line had significantly higher fecundity, lower embryonic and nymphal mortalities, and a lower level of CI than both the Wolbachia-infected Asia II7 IW line and the Cardinium-Wolbachia-coinfected Asia II7 ICWH line. Our findings indicate that Cardinium-Wolbachia coinfection induced male-killing, which may have had antagonistic effects on Wolbachia-induced CI in the Asia II7 whiteflies. For the first time, our study revealed that B. tabaci Asia II7 reproduction is co-manipulated by Cardinium and Wolbachia endosymbionts. This article is protected by copyright. All rights reserved.

RevDate: 2020-04-24

Coimbra-Dores MJ, Jaarsma RI, Carmo AO, et al (2020)

Mitochondrial sequences of Rhipicephalus and Coxiella endosymbiont reveal evidence of lineages co-cladogenesis.

FEMS microbiology ecology pii:5824628 [Epub ahead of print].

Rhipicephalus ticks are competent vectors of several pathogens, such as Spotted Fever Group Rickettsiae (SFGR) and many Babesia species. Within this genus, different R. sanguineus s.l. lineages show an unequal vector competence and resistance regarding some pathogenic strains. Current literature supports that tick endosymbionts may play an essential role in the transmission ability of a vector. Indeed, the microbial community of Rhipicephalus seems to be dominated by Coxiella-like endosymbionts (CLE). Still, their co-evolutionary associations with the complicated phylogeny of Rhipicephalus lineages and their transmissible pathogens remain unclear. We performed a phylogenetic congruence analysis to address whether divergent R. sanguineus s.l. lineages had a different symbiont composition. For that, we applied a PCR based approach to screen part of the microbial community present in 279 Rhipicephalus ticks from the Iberian Peninsula and Africa. Our analyses detected several qPCR-positive signals for both SFGR and Babesia species, of which we suggest R. sanguineus-tropical lineage as a natural vector of Babesia vogeli and R. sanguineus-temperate lineage of SFGR. The acquisition of 190 CLE sequences allowed to evaluate co-phylogenetic associations between the tick and the symbiont. With this data, we observed a strong but incomplete co-cladogenesis between CLE strains and their Rhipicephalus tick lineages hosts.

RevDate: 2020-04-22

Koto A, Nobu MK, R Miyazaki (2020)

Deep Sequencing Uncovers Caste-Associated Diversity of Symbionts in the Social Ant Camponotus japonicus.

mBio, 11(2): pii:mBio.00408-20.

Symbiotic microorganisms can have a profound impact on the host physiology and behavior, and novel relationships between symbionts and their hosts are continually discovered. A colony of social ants consists of various castes that exhibit distinct lifestyles and is, thus, a unique model for investigating how symbionts may be involved in host eusociality. Yet our knowledge of social ant-symbiont dynamics has remained rudimentary. Through 16S rRNA gene deep sequencing of the carpenter ant Camponotus japonicus symbiont community across various castes, we here report caste-dependent diversity of commensal gut microbiota and lineage divergence of "Candidatus Blochmannia," an obligate endosymbiont. While most prevalent gut-associated bacterial populations are found across all castes (Alphaproteobacteria, Gammaproteobacteria, Bacteroidetes, and Cyanobacteria), we also discovered uncultured populations that are found only in males (belonging to Corynebacteriales, Alkanindiges, and Burkholderia). Most of those populations are not detected in laboratory-maintained queens and workers, suggesting that they are facultative gut symbionts introduced via environmental acquisition. Further inspection of "Ca. Blochmannia" endosymbionts reveals that two populations are dominant in all individuals across all castes but that males preferentially contain two different sublineages that are diversified from others. Clearly, each caste has distinct symbiont communities, suggesting an overlooked biological aspect of host-symbiont interaction in social insects.IMPORTANCE Social animals, such as primates and some insects, have been shown to exchange symbiotic microbes among individuals through sharing diet or habitats, resulting in increased consistency of microbiota among social partners. The ant is a representative of social insects exhibiting various castes within a colony; queens, males, and nonreproductive females (so-called workers) show distinct morphologies, physiologies, and behaviors but tightly interact with each other in the nest. However, how this social context affects their gut microbiota has remained unclear. In this study, we deeply sequenced the gut symbiont community across various castes of the carpenter ant Camponotus japonicus We report caste-dependent diversity of commensal gut microbial community and lineage divergence of the mutualistic endosymbiont "Candidatus Blochmannia." This report sheds light on the hidden diversity in microbial populations and community structure associated with guts of males in social ants.

RevDate: 2020-04-14

Gabr A, Grossman AR, D Bhattacharya (2020)

Paulinella, a model for understanding plastid primary endosymbiosis.

Journal of phycology [Epub ahead of print].

The uptake and conversion of a free-living cyanobacterium into a photosynthetic organelle by the single-celled Archaeplastida ancestor helped transform the biosphere from low to high oxygen. There are two documented, independent cases of plastid primary endosymbiosis. The first is the well-studied instance in Archaeplastida that occurred ca. 1.6 billion years ago, whereas the second occurred 90-140 million years ago establishing a permanent photosynthetic compartment (the chromatophore) in amoebae in the genus Paulinella. Here, we briefly summarize knowledge about plastid origin in the Archaeplastida and then focus on the Paulinella model. In particular, we describe features of the Paulinella chromatophore that make it a model for examining earlier events in the evolution of photosynthetic organelles. Our review stresses recently gained insights into the evolution of chromatophore and nuclear encoded DNA sequences in Paulinella, metabolic connectivity between the endosymbiont and cytoplasm, and systems that target proteins into the chromatophore. We also describe future work with Paulinella, and the potential rewards and challenges associated with developing further this model system.

RevDate: 2020-04-11

Huang Z, Wang D, Li J, et al (2020)

Transovarial transmission of bacteriome-associated symbionts in the cicada Pycna repanda (Hemiptera: Cicadidae).

Applied and environmental microbiology pii:AEM.02957-19 [Epub ahead of print].

Although transovarial transmission of bacteriome-associated symbionts in hemipteran insects is extremely important for maintaining intimate host-symbiont associations, our knowledge of cellular mechanisms underlying the transmission process is quite limited. We investigated bacterial communities of salivary glands, bacteriomes and digestive and reproductive organs, and clarified the transovarial transmission of bacteriome-associated symbionts of the mountain-habitat specialist Pycna repanda using integrated methods. The bacterial communities among different gut tissues and those of bacteriomes of males and females both show similarity, whereas differences are exhibited among testes and ovaries. The primary symbionts Candidatus Sulcia muelleri (hereafter Sulcia) and Candidatus Hodgkinia cicadicola (hereafter Hodgkinia) were not only restricted to but also dominant in the bacteriomes and ovaries. Hodgkinia cells in the bacteriomes of both sexes exhibited different colors under histological and electron microscopy. Combined with the results of RFLP-based cloning approach, we hypothesize that Hodgkinia may have split into cytologically different cellular lineages within this cicada species. Regarding the dominant secondary symbionts, Rickettsia was detected in the salivary glands, digestive organs and testes, whereas Arsenophonus was in the bacteriomes and ovaries. Our results show that Arsenophonus can coexist with Sulcia and Hodgkinia within bacteriomes and can be transovarially transmitted with these obligate symbionts together from mother to offspring in cicadas, but it is not harbored in the cytoplasm of Sulcia. Sulcia and Hodgkinia shape change during the transovarial transmission process is hypothesized to be related to the limited space and novel microenvironment.IMPORTANCE Cicadas establish intimate symbiosis with microorganisms to obtain essential nutrients that are extremely deficient in the host plant sap. Previous studies on bacterial communities of cicadas mainly focused on a few widely distributed species, but knowledge is quite poor about the mountain-habitat species. We initially revealed the physical distribution of the primary symbionts Sulcia and Hodgkinia and the dominant secondary symbionts Rickettsia and Arsenophonus in the mountain-habitat specialist Pycna repanda, then clarified the transovarial transmission process of bacteriome-associated symbionts in this species. Our observations suggest that Hodgkinia may have split into cytologically distinct lineages within this cicada species, and related cicadas might have developed complex mechanisms for vertically transmitting of the bacteriome-associated symbionts. We also revealed that Arsenophonus can be transovarially transmitted in Auchenorrhynchan insects when it is not harbored in the cytoplasm of other endosymbiont. Our results highlight transovarial transmission mechanisms of bacteriome-associated symbionts in sap-feeding insects.

RevDate: 2020-04-11

Serteyn L, Quaghebeur C, Ongena M, et al (2020)

Induced Systemic Resistance by a Plant Growth-Promoting Rhizobacterium Impacts Development and Feeding Behavior of Aphids.

Insects, 11(4): pii:insects11040234.

The effects of microorganisms on plant-insect interactions have usually been underestimated. While plant growth-promoting rhizobacteria (PGPR) are known to induce plant defenses, endosymbiotic bacteria hosted by herbivorous insects are often beneficial to the host. Here, we aimed to assess whether PGPR-induced defenses in broad bean plants impact the pea aphid, depending on its genotype and the presence of endosymbionts. We estimated aphid reproduction, quantified defense- and growth-related phytohormones by GC-MS, and measured different plant growth and physiology parameters, after PGPR treatment. In addition, we recorded the feeding behavior of aphids by electropenetrography. We found that the PGPR treatment of broad bean plants reduced the reproduction of one of the pea aphid clones. We highlighted a phenomenon of PGPR-induced plant defense priming, but no noticeable plant growth promotion. The main changes in aphid probing behavior were related to salivation events into phloem sieve elements. We suggest that the endosymbiont Hamiltonella defensa played a key role in plant-insect interactions, possibly helping aphids to counteract plant-induced resistance and allowing them to develop normally on PGPR-treated plants. Our results imply that plant- and aphid-associated microorganisms add greater complexity to the outcomes of aphid-plant interactions.

RevDate: 2020-04-09

Domínguez-Santos R, Pérez-Cobas AE, Artacho A, et al (2020)

Unraveling Assemblage, Functions and Stability of the Gut Microbiota of Blattella germanica by Antibiotic Treatment.

Frontiers in microbiology, 11:487.

Symbiosis between prokaryotes and eukaryotes is a widespread phenomenon that has contributed to the evolution of eukaryotes. In cockroaches, two types of symbionts coexist: an endosymbiont in the fat body (Blattabacterium), and a rich gut microbiota. The transmission mode of Blattabacterium is vertical, while the gut microbiota of a new generation is mainly formed by bacterial species present in feces. We have carried out a metagenomic analysis of Blattella germanica populations, treated and non-treated with two antibiotics (vancomycin and ampicillin) over two generations to (1) determine the core of bacterial communities and potential functions of the gut microbiota and (2) to gain insights into the mechanisms of resistance and resilience of the gut microbiota. Our results indicate that the composition and functions of the bacteria were affected by treatment, more severely in the case of vancomycin. Further results demonstrated that in an untreated second-generation population that comes from antibiotic-treated first-generation, the microbiota is not yet stabilized at nymphal stages but can fully recover in adults when feces of a control population were added to the diet. This signifies the existence of a stable core in either composition and functions in lab-reared populations. The high microbiota diversity as well as the observed functional redundancy point toward the microbiota of cockroach hindguts as a robust ecosystem that can recover from perturbations, with recovery being faster when feces are added to the diet.

RevDate: 2020-04-04

Xu TT, Jiang LY, Chen J, et al (2020)

Host Plants Influence the Symbiont Diversity of Eriosomatinae (Hemiptera: Aphididae).

Insects, 11(4): pii:insects11040217.

Eriosomatinae is a particular aphid group with typically heteroecious holocyclic life cycle, exhibiting strong primary host plant specialization and inducing galls on primary host plants. Aphids are frequently associated with bacterial symbionts, which can play fundamental roles in the ecology and evolution of their host aphids. However, the bacterial communities in Eriosomatinae are poorly known. In the present study, using high-throughput sequencing of the bacterial 16S ribosomal RNA gene, we surveyed the bacterial flora of eriosomatines and explored the associations between symbiont diversity and aphid relatedness, aphid host plant and geographical distribution. The microbiota of Eriosomatinae is dominated by the heritable primary endosymbiont Buchnera and several facultative symbionts. The primary endosymbiont Buchnera is expectedly the most abundant symbiont across all species. Six facultative symbionts were identified. Regiella was the most commonly identified facultative symbiont, and multiple infections of facultative symbionts were detected in the majority of the samples. Ordination analyses and statistical tests show that the symbiont community of aphids feeding on plants from the family Ulmaceae were distinguishable from aphids feeding on other host plants. Species in Eriosomatinae feeding on different plants are likely to carry different symbiont compositions. The symbiont distributions seem to be not related to taxonomic distance and geographical distance. Our findings suggest that host plants can affect symbiont maintenance, and will improve our understanding of the interactions between aphids, their symbionts and ecological conditions.

RevDate: 2020-04-02

Guz N, Arshad M, Cagatay NS, et al (2020)

High Prevalence of Pantoea in Diaphorina citri (Hemiptera: Liviidae): Vector of Citrus Huanglongbing Disease.

Current microbiology pii:10.1007/s00284-020-01969-6 [Epub ahead of print].

As an important insect vector, Asian citrus psyllid (ACP), Diaphorina citri Kuwayama (Hemiptera: Liviidae) transmits the pathogen 'Candidatus Liberibacter asiaticus' (CLas) that is associated with citrus greening also known as Huanglongbing (HLB) disease. The bacterial endosymbionts have a potential role in shaping the host range of insect herbivores and their performance on different host plants, which might affect the endosymbiont distribution in insect populations. Here, we detected and characterized Pantoea endosymbiont in nymph and adult ACP specimens collected from Citrus reticulata Blanco and Cordia myxa L. plants. The phylogenetic tree constructed using endosymbiotic bacteria 16S ribosomal RNA sequences indicated that Pantoea sp. was closely related to Mixta calida, sharing about 98% identity and was grouped with other Mixta and Pantoea endosymbionts. Our findings showed 100% and 92.3% infection of Pantoea in adults while 61.5% and 90% infection of Pantoea in nymphs collected from C. reticulata and C. myxa plants, respectively. Understanding the interaction of endosymbiotic bacteria with ACP associated with host plants could be useful for developing an effective management strategy for both ACP and HLB disease.

RevDate: 2020-04-01

Huston DC (2019)

Collastoma esotericum (Neodalyellida: Umagillidae), a new species of sipunculan-inhabiting rhabdocoel from Queensland, Australia.

Zootaxa, 4701(6):zootaxa.4701.6.5 pii:zootaxa.4701.6.5.

The Umagillidae Wahl, represent a group of endosymbiotic Platyhelminthes which inhabit two disparate invertebrate host groups, the echinoderms and sipunculans. Sipunculan-inhabiting umagillids are morphologically distinct from those inhabiting echinoderms and have traditionally been placed in a distinct genus and subfamily, Collastoma Dörler, and the Collastominae Wahl, respectively. Although molecular data are available for umagillid species inhabiting echinoids and holothurians, species inhabiting sipunculans have yet to be evaluated with molecular data. Collastoma esotericum n. sp. from the sipunculan Phascolosoma scolops (Selenka & de Man) collected in Moreton Bay, southeast Queensland, Australia, is described. Phylogenetic analyses based on 18S rRNA gene sequences placed C. esotericum in a clade with species of the Umagillidae and the Provorticinae Luther, with strong support. However, within this clade the relationship of C. esotericum to the Umagillidae and Provorticinae was not resolved.

RevDate: 2020-03-27

Chen B, Yu K, Qin Z, et al (2020)

Dispersal, genetic variation, and symbiont interaction network of heat-tolerant endosymbiont Durusdinium trenchii: Insights into the adaptive potential of coral to climate change.

The Science of the total environment, 723:138026 pii:S0048-9697(20)31539-4 [Epub ahead of print].

Global warming has degraded coral reef ecosystems worldwide. Some corals develop thermal tolerance by associating with heat-tolerant Symbiodiniaceae. Here, we studied the mechanisms surrounding the dispersal, genetic variation and symbionts interaction of heat-tolerant Durusdinium trenchii across 13° latitudes in the South China Sea (SCS), to explore the possible mechanisms underlying these changes. Our results showed that Durusdinium trenchii are widely distributed in the seawater from the SCS. Our analyses of microsatellite loci revealed that D. trenchii has a high genetic diversity in the SCS; STRUCTURE analysis indicated that D. trenchii can be divided into four populations within the SCS; There exist positive correlations between genetic variation and geographic isolation, average sea surface temperature (SST) and variations in SST. Network modelling inferences showed that D. trenchii is a key species in the Symbiodiniaceae communities in the tropical SCS and contributes the greatest number of co-exclusion relationships. These results indicated that D. trenchii can affect the rare Symbiodiniaceae community. The long lifespan and the monsoon-driven ocean currents have shaped the wide distribution of D. trenchii. But low SST limits the ability of D. trenchii to establish stable symbioses with coral in the subtropical habitats. Geographical isolation and SST have shaped significant genetic variation of D.trenchii around the SCS. Our data reveals the biogeography and genetic population characteristics of D. trenchii in the Indo-Pacific region, and suggests that heat-tolerance and high genetic diversity of D. trenchii aid the corals with their adaptation to climate change.

RevDate: 2020-03-26

Paredes-Montero JR, Zia-Ur-Rehman M, Hameed U, et al (2020)

Genetic variability, community structure, and horizontal transfer of endosymbionts among three Asia II-Bemisia tabaci mitotypes in Pakistan.

Ecology and evolution, 10(6):2928-2943 pii:ECE36107.

Endosymbionts associated with the whitefly Bemisia tabaci cryptic species are known to contribute to host fitness and environmental adaptation. The genetic diversity and population complexity were investigated for endosymbiont communities of B. tabaci occupying different micro-environments in Pakistan. Mitotypes of B. tabaci were identified by comparative sequence analysis of the mitochondria cytochrome oxidase I (mtCOI) gene sequence. Whitefly mitotypes belonged to the Asia II-1, -5, and -7 mitotypes of the Asia II major clade. The whitefly-endosymbiont communities were characterized based on 16S ribosomal RNA operational taxonomic unit (OTU) assignments, resulting in 43 OTUs. Most of the OTUs occurred in the Asia II-1 and II-7 mitotypes (r2 = .9, p < .005), while the Asia II-5 microbiome was less complex. The microbiome OTU groups were mitotype-specific, clustering with a basis in phylogeographical distribution and the corresponding ecological niche of their whitefly host, suggesting mitotype-microbiome co-adaptation. The primary endosymbiont Portiera was represented by a single, highly homologous OTU (0%-0.67% divergence). Two of six Arsenophonus OTUs were uniquely associated with Asia II-5 and -7, and one occurred exclusively in Asia II-1, two only in Asia II-5, and one in both Asia II-1 and -7. Four other secondary endosymbionts, Cardinium, Hemipteriphilus, Rickettsia, and Wolbachia OTUs, were found at ≤29% frequencies. The most prevalent Arsenophonus OTU was found in all three Asia II mitotypes (55% frequency), whereas the same strain of Cardinium and Wolbachia was found in both Asia II-1 and -5, and a single Hemipteriphilus OTU occurred in Asia II-1 and -7. This pattern is indicative of horizontal transfer, suggestive of a proximity between mitotypes sufficient for gene flow at overlapping mitotype ecological niches.

RevDate: 2020-03-19

Dionysopoulou NK, Papanastasiou SA, Kyritsis GA, et al (2020)

Effect of host fruit, temperature and Wolbachia infection on survival and development of Ceratitis capitata immature stages.

PloS one, 15(3):e0229727 pii:PONE-D-19-25021.

The Mediterranean fruit fly, Ceratitis capitata (Diptera: Tephritidae), holds an impressive record of successful invasions promoted by the growth and development of international fruit trade. Hence, survival of immatures within infested fruit that are subjected to various conditions during transportation seems to be a crucial feature that promotes invasion success. Wolbachia pipientis is a common endosymbiont of insects and other arthropods generating several biological effects on its hosts. Existing information report the influence of Wolbachia on the fitness traits of insect host species, including the Mediterranean fruit fly. However, little is known regarding effects of Wolbachia infection on immature development in different host fruits and temperatures. This study was conducted to determine the development and survival of immature stages of four different Mediterranean fruit fly populations, either infected or uninfected with Wolbachia, in two hosts (apples, bitter oranges) under three constant temperatures (15, 25 and 30°C), constant relative humidity (45-55 ± 5%), and a photoperiod of 14L:10D. Our findings demonstrate both differential response of two fruit fly lines to Wolbachia infection and differential effects of the two Wolbachia strains on the same Mediterranean fruit fly line. Larva-to-pupa and larva-to-adult survival followed similar patterns and varied a lot among the four medfly populations, the two host fruits and the different temperatures. Pupation rates and larval developmental time were higher for larvae implanted in apples compared to bitter oranges. The survival rates of wildish medflies were higher than those of the laboratory adapted ones, particularly in bitter oranges. The Wolbachia infected medflies, expressed lower survival rates and higher developmental times, especially the wCer4 infected line. High temperatures constrained immature development and were lethal for the Wolbachia infected wCer4 medfly line. Lower temperatures inferred longer developmental times to immature stages of all medfly populations tested, in both host fruits. Implications on the ecology and survival of the fly in nature are discussed.

RevDate: 2020-03-18

García-Del Portillo F (2020)

Building peptidoglycan inside eukaryotic cells: A view from symbiotic and pathogenic bacteria.

Molecular microbiology, 113(3):613-626.

The peptidoglycan (PG), as the exoskeleton of most prokaryotes, maintains a defined shape and ensures cell integrity against the high internal turgor pressure. These important roles have attracted researchers to target PG metabolism in order to control bacterial infections. Most studies, however, have been performed in bacteria grown under laboratory conditions, leading to only a partial view on how the PG is synthetized in natural environments. As a case in point, PG metabolism and its regulation remain poorly understood in symbiotic and pathogenic bacteria living inside eukaryotic cells. This review focuses on the PG metabolism of intracellular bacteria, emphasizing the necessity of more in vivo studies involving the analysis of enzymes produced in the intracellular niche and the isolation of PG from bacteria residing within eukaryotic cells. The review also points to persistent infections caused by some intracellular bacterial pathogens and the extent at which the PG could contribute to establish such physiological state. Based on recent evidences, I speculate on the idea that certain structural features of the PG may facilitate attenuation of intracellular growth. Lastly, I discuss recent findings in endosymbionts supporting a cooperation between host and bacterial enzymes to assemble a mature PG.


RJR Experience and Expertise


Robbins holds BS, MS, and PhD degrees in the life sciences. He served as a tenured faculty member in the Zoology and Biological Science departments at Michigan State University. He is currently exploring the intersection between genomics, microbial ecology, and biodiversity — an area that promises to transform our understanding of the biosphere.


Robbins has extensive experience in college-level education: At MSU he taught introductory biology, genetics, and population genetics. At JHU, he was an instructor for a special course on biological database design. At FHCRC, he team-taught a graduate-level course on the history of genetics. At Bellevue College he taught medical informatics.


Robbins has been involved in science administration at both the federal and the institutional levels. At NSF he was a program officer for database activities in the life sciences, at DOE he was a program officer for information infrastructure in the human genome project. At the Fred Hutchinson Cancer Research Center, he served as a vice president for fifteen years.


Robbins has been involved with information technology since writing his first Fortran program as a college student. At NSF he was the first program officer for database activities in the life sciences. At JHU he held an appointment in the CS department and served as director of the informatics core for the Genome Data Base. At the FHCRC he was VP for Information Technology.


While still at Michigan State, Robbins started his first publishing venture, founding a small company that addressed the short-run publishing needs of instructors in very large undergraduate classes. For more than 20 years, Robbins has been operating The Electronic Scholarly Publishing Project, a web site dedicated to the digital publishing of critical works in science, especially classical genetics.


Robbins is well-known for his speaking abilities and is often called upon to provide keynote or plenary addresses at international meetings. For example, in July, 2012, he gave a well-received keynote address at the Global Biodiversity Informatics Congress, sponsored by GBIF and held in Copenhagen. The slides from that talk can be seen HERE.


Robbins is a skilled meeting facilitator. He prefers a participatory approach, with part of the meeting involving dynamic breakout groups, created by the participants in real time: (1) individuals propose breakout groups; (2) everyone signs up for one (or more) groups; (3) the groups with the most interested parties then meet, with reports from each group presented and discussed in a subsequent plenary session.


Robbins has been engaged with photography and design since the 1960s, when he worked for a professional photography laboratory. He now prefers digital photography and tools for their precision and reproducibility. He designed his first web site more than 20 years ago and he personally designed and implemented this web site. He engages in graphic design as a hobby.

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Collection of publications by R J Robbins

Reprints and preprints of publications, slide presentations, instructional materials, and data compilations written or prepared by Robert Robbins. Most papers deal with computational biology, genome informatics, using information technology to support biomedical research, and related matters.

Research Gate page for R J Robbins

ResearchGate is a social networking site for scientists and researchers to share papers, ask and answer questions, and find collaborators. According to a study by Nature and an article in Times Higher Education , it is the largest academic social network in terms of active users.

Curriculum Vitae for R J Robbins

short personal version

Curriculum Vitae for R J Robbins

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