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26 Jun 2019 at 01:35
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Bibliography on: Symbiosis


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RJR: Recommended Bibliography 26 Jun 2019 at 01:35 Created: 


Symbiosis refers to an interaction between two or more different organisms living in close physical association, typically to the advantage of both. Symbiotic relationships were once thought to be exceptional situations. Recent studies, however, have shown that every multicellular eukaryote exists in a tight symbiotic relationship with billions of microbes. The associated microbial ecosystems are referred to as microbiome and the combination of a multicellular organism and its microbiota has been described as a holobiont. It seems "we are all lichens now."

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Citations The Papers (from PubMed®)

RevDate: 2019-06-24

Cui G, Liew YJ, Li Y, et al (2019)

Host-dependent nitrogen recycling as a mechanism of symbiont control in Aiptasia.

PLoS genetics, 15(6):e1008189 pii:PGENETICS-D-18-02321 [Epub ahead of print].

The metabolic symbiosis with photosynthetic algae allows corals to thrive in the oligotrophic environments of tropical seas. Different aspects of this relationship have been investigated using the emerging model organism Aiptasia. However, many fundamental questions, such as the nature of the symbiotic relationship and the interactions of nutrients between the partners remain highly debated. Using a meta-analysis approach, we identified a core set of 731 high-confidence symbiosis-associated genes that revealed host-dependent recycling of waste ammonium and amino acid synthesis as central processes in this relationship. Subsequent validation via metabolomic analyses confirmed that symbiont-derived carbon enables host recycling of ammonium into nonessential amino acids. We propose that this provides a regulatory mechanism to control symbiont growth through a carbon-dependent negative feedback of nitrogen availability to the symbiont. The dependence of this mechanism on symbiont-derived carbon highlights the susceptibility of this symbiosis to changes in carbon translocation, as imposed by environmental stress.

RevDate: 2019-06-24

Bapaume L, Laukamm S, Darbon G, et al (2019)

VAPYRIN Marks an Endosomal Trafficking Compartment Involved in Arbuscular Mycorrhizal Symbiosis.

Frontiers in plant science, 10:666.

Arbuscular mycorrhiza (AM) is a symbiosis between plants and AM fungi that requires the intracellular accommodation of the fungal partner in the host. For reciprocal nutrient exchange, AM fungi form intracellular arbuscules that are surrounded by the peri-arbuscular membrane. This membrane, together with the fungal plasma membrane, and the space in between, constitute the symbiotic interface, over which nutrients are exchanged. Intracellular establishment of AM fungi requires the VAPYRIN protein which is induced in colonized cells, and which localizes to numerous small mobile structures of unknown identity (Vapyrin-bodies). In order to characterize the identity and function of the Vapyrin-bodies we pursued a dual strategy. First, we co-expressed fluorescently tagged VAPYRIN with a range of subcellular marker proteins, and secondly, we employed biochemical tools to identify interacting partner proteins of VAPYRIN. As an important tool for the quantitative analysis of confocal microscopic data sets from co-expression of fluorescent proteins, we developed a semi-automated image analysis pipeline that allows for precise spatio-temporal quantification of protein co-localization and of the dynamics of organelle association from movies. Taken together, these experiments revealed that Vapyrin-bodies have an endosomal identity with trans-Golgi features, and that VAPYRIN interacts with a symbiotic R-SNARE of the VAMP721 family, that localizes to the same compartment.

RevDate: 2019-06-24

Miozzi L, Vaira AM, Catoni M, et al (2019)

Arbuscular Mycorrhizal Symbiosis: Plant Friend or Foe in the Fight Against Viruses?.

Frontiers in microbiology, 10:1238.

Plant roots establish interactions with several beneficial soil microorganisms including arbuscular mycorrhizal fungi (AMF). In addition to promoting plant nutrition and growth, AMF colonization can prime systemic plant defense and enhance tolerance to a wide range of environmental stresses and below-ground pathogens. A protective effect of the AMF against above-ground pathogens has also been described in different plant species, but it seems to largely rely on the type of attacker. Viruses are obligate biotrophic pathogens able to infect a large number of plant species, causing massive losses in crop yield worldwide. Despite their economic importance, information on the effect of the AM symbiosis on viral infection is limited and not conclusive. However, several experimental evidences, obtained under controlled conditions, show that AMF colonization may enhance viral infection, affecting susceptibility, symptomatology and viral replication, possibly related to the improved nutritional status and to the delayed induction of pathogenesis-related proteins in the mycorrhizal plants. In this review, we give an overview of the impact of the AMF colonization on plant infection by pathogenic viruses and summarize the current knowledge of the underlying mechanisms. For the cases where AMF colonization increases the susceptibility of plants to viruses, the term "mycorrhiza-induced susceptibility" (MIS) is proposed.

RevDate: 2019-06-24

Liu H, Senthilkumar R, Ma G, et al (2019)

Piriformospora indica-induced phytohormone changes and root colonization strategies are highly host-specific.

Plant signaling & behavior [Epub ahead of print].

Piriformospora indica, an endophytic fungus of Sebacinales, has a wide host range and promotes the performance of mono- and eudicot plants. Here, we compare the interaction of P. indica with the roots of seven host plants (Anthurium andraeanum, Arabidopsis thaliana, Brassica campestris, Lycopersicon esculentum, Oncidium orchid, Oryza sativa, and Zea mays). Microscopical analyses showed that the colonization time and the mode of hyphal invasion into the roots differ in the symbiotic interactions. Substantial differences between the species were also observed for the levels and accumulation of jasmonate (JA) and gibberellin (GA) and the transcript levels for genes involved in their syntheses. No obvious correlation could be detected between the endogenous JA and/or GA levels and the time point of root colonization in a given plant species. Our results suggest that root colonization strategies and changes in the two phytohormone levels are highly host-specific.

RevDate: 2019-06-23

Petrzik K (2019)

Evolutionary forces at work in partitiviruses.

Virus genes pii:10.1007/s11262-019-01680-0 [Epub ahead of print].

The family Partitiviridae consists of dsRNA viruses with genome separated into two segments and encoding replicase and capsid protein only. We examined the nucleotide diversity expressed as the ratio dN/dS of nonsynonymous and synonymous substitutions, which has been calculated for 12 representative viruses of all five genera of partitiviruses. We can state that strong purifying selection works on both the RdRp and CP genes and propose that putative positive selection occurs also on the RdRp genes in two viruses. Among the 95 evaluated viruses, wherein both segments had been sequenced, 8 viruses in betapartitiviruses and 9 in alphapartitiviruses were identified as reassortment candidates because they differ extremely in their CP identity even as they are related in terms of RdRp. Furthermore, there are indications that reassortants are present among isolates of different viruses.

RevDate: 2019-06-23

Roper C, Castro C, B Ingel (2019)

Xylella fastidiosa: bacterial parasitism with hallmarks of commensalism.

Current opinion in plant biology, 50:140-147 pii:S1369-5266(18)30152-3 [Epub ahead of print].

All organisms evolve in the presence of other organisms and these intimate associations are major drivers of evolution. Broadly speaking, these interactions are considered symbioses and can take on a full range of positive, negative or seemingly neutral interactions. Just two examples of these symbiotic interactions are parasitism and commensalism. Parasitism results in one partner benefitting while one partner suffers adverse consequences. Commensalism is a form of symbiosis where one partner benefits and the other partner is neutrally affected. Research efforts are more often focused on understanding parasitic symbioses related to disease, hence, much research is performed on identifying virulence factors to understand the fundamentals of pathogenesis. In turn, much less is understood about the fundamentals of commensal relationships. Here, we will take an introspective look at the plant-associated bacterium, Xylella fastidiosa. In some of its many plant hosts, this bacterium participates in seemingly commensal relationships while in other hosts, it causes devastating diseases that result in epidemics, making it a good model for exploring the determinants of where bacteria fall on the spectrum of parasitic and commensal relationships from both the microbial and the plant host perspective. Recent discoveries in how pathogenic X. fastidiosa imposes self-limiting behaviors upon itself indicate that even in its parasitic form, X. fastidiosa displays hallmarks of a commensal lifestyle. Understanding how commensalism can 'go wrong' and manifest into pathologies in specific hosts is a useful vantage point from which to study the determinants of virulence and pathogenicity.

RevDate: 2019-06-23

Zhang R, Yang Y, Wang J, et al (2019)

Synthetic symbiosis combining plasmid displacement enables rapid construction of phenotype-stable strains.

Metabolic engineering pii:S1096-7176(19)30190-9 [Epub ahead of print].

Plasmid-based microbial systems have been a major workhorse for chemical and pharmaceutical production. The biosafety issues and elevated industrial cost of antibiotic usage have led to the development of alternative strategies for plasmid selection and maintenance. Such strategies, including auxotrophy complementation, post-segregational killing, operator-repressor and RNA-based interactions often require extensive engineering of various elements and may result in extra metabolic burden in the cells. Herein, we report a design of synthetic symbiosis combining plasmid displacement to construct a phenotype-stable microbial system. By sequestrating an endogenous essential gene folP, cells obtained long-term plasmid maintenance with minimum cost. The phenotype performance was also inherited for up to 80 generations demonstrated by the production of salicylic acid in Escherichia coli. Meanwhile, the temperature-induced curing method of the intermediate plasmids enables rapid engineering. This design can lead to broad applications as a reliable and convenient plasmid-based expression system.

RevDate: 2019-06-24
CmpDate: 2019-06-24

Li Q, Ren Y, X Fu (2019)

Inter-kingdom signaling between gut microbiota and their host.

Cellular and molecular life sciences : CMLS, 76(12):2383-2389.

The crosstalk between prokaryotic bacteria and eukaryotic gut epithelial cells has opened a new field for research. Quorum sensing system (QS) molecules employed by gut microbiota may play an essential role in host-microbial symbioses of the gut. Recent studies on the gut microbiome will unveil evolved mechanisms of the host to affect bacterial QS and shape bacterial composition. Bacterial autoinducers (AIs) could talk to the host's gut by eliciting proinflammatory effects and modulating the activities of T lymphocyte, macrophage, dendritic cells, and neutrophils. In addition, the gut mucosa could interfere with bacterial AIs by degrading them or secreting AI mimics. Moreover, bacterial AIs and gut hormones epinephrine and noradrenaline may be interchangeable in the crosstalk between the microbiota and human gut. Therefore, inter-kingdom signaling between gut microbiota and host may provide a novel target in the management of gut microbiota-related conditions or diseases in the future.

RevDate: 2019-06-24
CmpDate: 2019-06-24

Sottorff I, Künzel S, Wiese J, et al (2019)

Antitumor Anthraquinones from an Easter Island Sea Anemone: Animal or Bacterial Origin?.

Marine drugs, 17(3): pii:md17030154.

The presence of two known anthraquinones, Lupinacidin A and Galvaquinone B, which have antitumor activity, has been identified in the sea anemone (Gyractis sesere) from Easter Island. So far, these anthraquinones have been characterized from terrestrial and marine Actinobacteria only. In order to identify the anthraquinones producer, we isolated Actinobacteria associated with the sea anemone and obtained representatives of seven actinobacterial genera. Studies of cultures of these bacteria by HPLC, NMR, and HRLCMS analyses showed that the producer of Lupinacidin A and Galvaquinone B indeed was one of the isolated Actinobacteria. The producer strain, SN26_14.1, was identified as a representative of the genus Verrucosispora. Genome analysis supported the biosynthetic potential to the production of these compounds by this strain. This study adds Verrucosispora as a new genus to the anthraquinone producers, in addition to well-known species of Streptomyces and Micromonospora. By a cultivation-based approach, the responsibility of symbionts of a marine invertebrate for the production of complex natural products found within the animal's extracts could be demonstrated. This finding re-opens the debate about the producers of secondary metabolites in sea animals. Finally, it provides valuable information about the chemistry of bacteria harbored in the geographically-isolated and almost unstudied, Easter Island.

RevDate: 2019-06-24
CmpDate: 2019-06-24

Suetsugu K, Ohta T, I Tayasu (2018)

Partial mycoheterotrophy in the leafless orchid Cymbidium macrorhizon.

American journal of botany, 105(9):1595-1600.

PREMISE OF THE STUDY: The evolution of full mycoheterotrophy is one of the most interesting topics within plant evolution. The leafless orchid Cymbidium macrorhizon is often assumed to be fully mycoheterotrophic even though it has a green stem and fruit capsule. Here, we assessed the trophic status of this species by analyzing the chlorophyll content and the natural 13 C and 15 N abundance in the sprouting and the fruiting season.

METHODS: The chlorophyll content was measured in five sprouting and five fruiting individuals of C. macrorhizon that were co-occurring. In addition, their 13 C and 15 N isotopic signatures were compared with those of neighboring autotrophic and partially mycoheterotrophic reference plants.

KEY RESULTS: Fruiting individuals of C. macrorhizon were found to contain a remarkable amount of chlorophyll compared to their sprouting counterparts. In addition, the natural abundance of 13 C in the tissues of the fruiting plants was slightly depleted relative to the sprouting ones. Linear two-source mixing model analysis revealed that fruiting C. macrorhizon plants obtained approximately 73.7 ± 2.0% of their total carbon from their mycorrhizal fungi when the sprouting individuals were used as the 100% carbon gain standard.

CONCLUSIONS: Our results indicated that despite its leafless status, fruiting plants of C. macrorhizon were capable of fixing significant quantities of carbon. Considering the autotrophic carbon gain increases during the fruiting season, its photosynthetic ability may contribute to fruit and seed production. These results indicate that C. macrorhizon should, therefore, be considered a partially mycoheterotrophic species rather than fully mycoheterotrophic, at least during the fruiting stage.

RevDate: 2019-06-24
CmpDate: 2019-06-24

Chen C, Linse K, Uematsu K, et al (2018)

Cryptic niche switching in a chemosymbiotic gastropod.

Proceedings. Biological sciences, 285(1882):.

Life stages of some animals, including amphibians and insects, are so different that they have historically been seen as different species. 'Metamorphosis' broadly encompasses major changes in organism bodies and, importantly, concomitant shifts in trophic strategies. Many marine animals have a biphasic lifestyle, with small pelagic larvae undergoing one or more metamorphic transformations before settling into a permanent, adult morphology on the benthos. Post-settlement, the hydrothermal vent gastropod Gigantopelta chessoia experiences a further, cryptic metamorphosis at body sizes around 5-7 mm. The terminal adult stage is entirely dependent on chemoautotrophic symbionts; smaller individuals do not house symbionts and presumably depend on grazing. Using high-resolution X-ray microtomography to reconstruct the internal organs in a growth series, we show that this sudden transition in small but sexually mature individuals dramatically reconfigures the organs, but is in no way apparent from external morphology. We introduce the term 'cryptometamorphosis' to identify this novel phenomenon of a major body change and trophic shift, not related to sexual maturity, transforming only the internal anatomy. Understanding energy flow in ecosystems depends on the feeding ecology of species; the present study highlights the possibility for adult animals to make profound shifts in biology that influence energy dynamics.

RevDate: 2019-06-22

Dhaouefi Z, Toledo-Cervantes A, Ghedira K, et al (2019)

Decolorization and phytotoxicity reduction in an innovative anaerobic/aerobic photobioreactor treating textile wastewater.

Chemosphere, 234:356-364 pii:S0045-6535(19)31347-5 [Epub ahead of print].

The potential of a novel anaerobic/aerobic algal-bacterial photobioreactor for the treatment of synthetic textile wastewater (STWW) was here assessed. Algal-bacterial symbiosis supported total organic carbon, nitrogen and phosphorous removal efficiencies of 78 ± 2%, 47 ± 2% and 26 ± 2%, respectively, at a hydraulic retention time (HRT) of 8 days. A decrease in the HRT from 8 to 4 and 2 days resulted in a slight decrease in organic carbon and phosphate removal, but a sharp decrease in nitrogen removal. Moreover, an efficient decolorization of 99 ± 1% and 96 ± 3% for disperse orange-3 and of disperse blue-1, respectively, was recorded. The effective STWW treatment supported by the anaerobic/aerobic algal-bacterial photobioreactor was confirmed by the reduction in wastewater toxicity towards Raphanus sativus seed germination and growth. These results highlighted the potential of this innovative algal-bacterial photobioreactor configuration for the treatment of textile wastewater and water reuse.

RevDate: 2019-06-22

Babadi M, Zalaghi R, M Taghavi (2019)

A non-toxic polymer enhances sorghum-mycorrhiza symbiosis for bioremediation of Cd.

Mycorrhiza pii:10.1007/s00572-019-00902-5 [Epub ahead of print].

In this study, the effect of a mycorrhizal symbiosis on the translocation of Cd from Cd-polluted soil to sorghum roots was investigated using rhizoboxes. A factorial experiment (two factors including fungus inoculation and Cd contamination) in a completely randomized design with three replicates was performed. In the rhizobox rhizosphere compartment, plants were cultivated in uncontaminated soil and mycorrhizal inoculation (inoculated with Claroideoglomus etunicatum or non-inoculated) was performed, and in the other compartment, the soil was contaminated with Cadmium (Cd) at one of three levels (0, 100 mg kg-1 using a non-toxic organic polymer (poly (N-vinyl succinate))-Cd, or 100 mg kg-1 using Cd-nitrate). Cd pollution resulted in a significant decrease in shoot dry weight (from 7.52 to 6.18 and 6.68 g pot-1, from control to polymer-Cd and nitrate-Cd respectively), root mycorrhizal colonization (from 32.33% to 8.16% and 8.33%), shoot phosphorus concentration (from 3.14 to 2.80 and 2.76 g kg-1), and soil carbohydrate (from 12.05 to 10.74 and 10.24 mg g-1), and also resulted in significant increases in soil glomalin (from 595.55 to 660.52 and 690.39 μg g-1). The use of mycorrhizal fungi increased the glomalin content of the soil and improved the studied parameters. The results revealed the key role of Claroideoglomus etunicatum in translocation of Cd in the rhizobox and also in precise control of Cd concentration of plant tissues (increase or decrease of them depending on Cd composition and Cd availability). Poly(N-vinyl succinate) increased Cd availability and Cd concentration of shoot tissue (5.19 mg kg-1) compared to nitrate-Cd (3.68 mg kg-1) and could be recommended for improving phytoremediation.

RevDate: 2019-06-22

Mei YZ, Zhu YL, Huang PW, et al (2019)

Strategies for gene disruption and expression in filamentous fungi.

Applied microbiology and biotechnology pii:10.1007/s00253-019-09953-2 [Epub ahead of print].

Filamentous fungi can produce many valuable secondary metabolites; among these fungi, endophytic fungi play an ecological role in mutualistic symbiosis with plants, including promoting plant growth, disease resistance, and stress resistance. However, the biosynthesis of most secondary metabolites remains unclear, and knowledge of the interaction mechanisms between endophytes and plants is still limited, especially for some novel fungi, due to the lack of genetic manipulation tools for novel species. Herein, we review the newly discovered strategies of gene disruption, such as the CRISPR-Cas9 system, the site-specific recombination Cre/loxP system, and the I-SceI endonuclease-mediated system in filamentous fungi. Gene expression systems contain using integration of target genes into the genome, host-dependent expression cassette construction depending on the host, a host-independent, universal expression system independent of the host, and reporter-guided gene expression for filamentous fungi. Furthermore, the Newly CRISPRi, CRISPRa, and the selection markers were also discussed for gene disruption and gene expression were also discussed. These studies lay the foundation for the biosynthesis of secondary metabolites in these organisms and aid in understanding the ecological function of filamentous fungi.

RevDate: 2019-06-21
CmpDate: 2019-06-21

Sibbald SJ, Hopkins JF, Filloramo GV, et al (2019)

Ubiquitin fusion proteins in algae: implications for cell biology and the spread of photosynthesis.

BMC genomics, 20(1):38 pii:10.1186/s12864-018-5412-4.

BACKGROUND: The process of gene fusion involves the formation of a single chimeric gene from multiple complete or partial gene sequences. Gene fusion is recognized as an important mechanism by which genes and their protein products can evolve new functions. The presence-absence of gene fusions can also be useful characters for inferring evolutionary relationships between organisms.

RESULTS: Here we show that the nuclear genomes of two unrelated single-celled algae, the cryptophyte Guillardia theta and the chlorarachniophyte Bigelowiella natans, possess an unexpected diversity of genes for ubiquitin fusion proteins, including novel arrangements in which ubiquitin occupies amino-terminal, carboxyl-terminal, and internal positions relative to its fusion partners. We explore the evolution of the ubiquitin multigene family in both genomes, and show that both algae possess a gene encoding an ubiquitin-nickel superoxide dismutase fusion protein (Ubiq-NiSOD) that is widely but patchily distributed across the eukaryotic tree of life - almost exclusively in phototrophs.

CONCLUSION: Our results suggest that ubiquitin fusion proteins are more common than currently appreciated; because of its small size, the ubiquitin coding region can go undetected when gene predictions are carried out in an automated fashion. The punctate distribution of the Ubiq-NiSOD fusion across the eukaryotic tree could serve as a beacon for the spread of plastids from eukaryote to eukaryote by secondary and/or tertiary endosymbiosis.

RevDate: 2019-06-21
CmpDate: 2019-06-21

Rey F, Costa ED, Campos AM, et al (2017)

Kleptoplasty does not promote major shifts in the lipidome of macroalgal chloroplasts sequestered by the sacoglossan sea slug Elysia viridis.

Scientific reports, 7(1):11502.

Sacoglossan sea slugs, also known as crawling leaves due to their photosynthetic activity, are highly selective feeders that incorporate chloroplasts from specific macroalgae. These "stolen" plastids - kleptoplasts - are kept functional inside animal cells and likely provide an alternative source of energy to their host. The mechanisms supporting the retention and functionality of kleptoplasts remain unknown. A lipidomic mass spectrometry-based analysis was performed to study kleptoplasty of the sacoglossan sea slug Elysia viridis fed with Codium tomentosum. Total lipid extract of both organisms was fractionated. The fraction rich in glycolipids, exclusive lipids from chloroplasts, and the fraction rich in betaine lipids, characteristic of algae, were analysed using hydrophilic interaction liquid chromatography-mass spectrometry (HILIC-LC-MS). This approach allowed the identification of 81 molecular species, namely galactolipids (8 in both organisms), sulfolipids (17 in C. tomentosum and 13 in E. viridis) and betaine lipids (51 in C. tomentosum and 41 in E. viridis). These lipid classes presented similar lipidomic profiles in C. tomentosum and E. viridis, indicating that the necessary mechanisms to perform photosynthesis are preserved during the process of endosymbiosis. The present study shows that there are no major shifts in the lipidome of C. tomentosum chloroplasts sequestered by E. viridis.

RevDate: 2019-06-20

Muletz-Wolz CR, Kurata NP, Himschoot EA, et al (2019)

Diversity and temporal dynamics of primate milk microbiomes.

American journal of primatology [Epub ahead of print].

Milk is inhabited by a community of bacteria and is one of the first postnatal sources of microbial exposure for mammalian young. Bacteria in breast milk may enhance immune development, improve intestinal health, and stimulate the gut-brain axis for infants. Variation in milk microbiome structure (e.g., operational taxonomic unit [OTU] diversity, community composition) may lead to different infant developmental outcomes. Milk microbiome structure may depend on evolutionary processes acting at the host species level and ecological processes occurring over lactation time, among others. We quantified milk microbiomes using 16S rRNA high-throughput sequencing for nine primate species and for six primate mothers sampled over lactation. Our data set included humans (Homo sapiens, Philippines and USA) and eight nonhuman primate species living in captivity (bonobo [Pan paniscus], chimpanzee [Pan troglodytes], western lowland gorilla [Gorilla gorilla gorilla], Bornean orangutan [Pongo pygmaeus], Sumatran orangutan [Pongo abelii], rhesus macaque [Macaca mulatta], owl monkey [Aotus nancymaae]) and in the wild (mantled howler monkey [Alouatta palliata]). For a subset of the data, we paired microbiome data with nutrient and hormone assay results to quantify the effect of milk chemistry on milk microbiomes. We detected a core primate milk microbiome of seven bacterial OTUs indicating a robust relationship between these bacteria and primate species. Milk microbiomes differed among primate species with rhesus macaques, humans and mantled howler monkeys having notably distinct milk microbiomes. Gross energy in milk from protein and fat explained some of the variations in microbiome composition among species. Microbiome composition changed in a predictable manner for three primate mothers over lactation time, suggesting that different bacterial communities may be selected for as the infant ages. Our results contribute to understanding ecological and evolutionary relationships between bacteria and primate hosts, which can have applied benefits for humans and endangered primates in our care.

RevDate: 2019-06-20

Khatabi B, Gharechahi J, Ghaffari MR, et al (2019)

Plant-microbe symbiosis: What has proteomics taught us?.

Proteomics [Epub ahead of print].

Beneficial plant-microbes can have a positive impact on the productivity and fitness of the host plant. A better understanding of the biological impacts and underlying mechanisms by which the host derives these benefits will help to address concerns around global food production and security. The recent development of omics-based technologies has broadened our understanding of the molecular aspects of beneficial plant-microbe symbiosis. Specifically, proteomics has led to the identification and characterization of several novel symbiosis-specific and symbiosis-related proteins and post-translational modifications which play a critical role in mediating symbiotic plant-microbe interactions and have help to assess the underlying molecular aspects of the symbiotic relationship, including the developmental stages of legume-Rhizobium symbiosis and other non-legume based relationships. Functional proteomics and the study of protein interactions will help provide a better understanding of the protein-protein interaction networks associated with plant-microbe symbiosis and the during the developmental stages of the symbiotic process. Integration of proteomic data with other "omics" data can provide valuable information to assess hypotheses regarding the underlying mechanism of symbiosis and help to define the factors affecting the outcome of symbiosis. In this review, we provide an update on the current and potential applications of symbiosis based "omic" approaches to dissect different aspects of symbiotic plant interactions. We also discuss the application of proteomics, metaproteomics and secretomics as enabling approaches for the functional analysis of plant-associated microbial communities. This article is protected by copyright. All rights reserved.

RevDate: 2019-06-20

Motaharpoor Z, Taheri H, H Nadian (2019)

Rhizophagus irregularis modulates cadmium uptake, metal transporter, and chelator gene expression in Medicago sativa.

Mycorrhiza pii:10.1007/s00572-019-00900-7 [Epub ahead of print].

Arbuscular mycorrhizal fungi (AMF) are considered a potential biotechnological tool for mitigating heavy metal (HM) toxicity. A greenhouse experiment was conducted to evaluate the impacts of the AM fungus Rhizophagus irregularis on cadmium (Cd) uptake, mycorrhizal colonization, and some plant growth parameters of Medicago sativa (alfalfa) in Cd-polluted soils. In addition, expression of two metal chelators (MsPCS1 (phytochelatin synthase) and MsMT2 (metallothionein)) and two metal transporter genes (MsIRT1 and MsNramp1) was analyzed using quantitative real-time PCR (qRT-PCR). Cd addition had a significant negative effect on mycorrhizal colonization. However, AMF symbiosis promoted the accumulation of biomass under both stressed and unstressed conditions compared with non-mycorrhizal (NM) plants. Results also showed that inoculation with R. irregularis significantly reduced shoot Cd concentration in polluted soils. Transcripts abundance of MsPCS1, MsMT2, MsIRT1, and MsNRAMP1 genes were downregulated compared with NM plants indicating that metal sequestration within hyphal fungi probably made Cd concentration insufficient in root cells for induction of these genes. These results suggest that reduction of shoot Cd concentration in M. sativa colonized by R. irregularis could be a promising strategy for safe production of this plant in Cd-polluted soils.

RevDate: 2019-06-20

Della Mónica IF, Godeas AM, JM Scervino (2019)

In Vivo Modulation of Arbuscular Mycorrhizal Symbiosis and Soil Quality by Fungal P Solubilizers.

Microbial ecology pii:10.1007/s00248-019-01396-6 [Epub ahead of print].

Phosphorus (P) is an essential nutrient with low bioavailability in soils for plant growth. The use of P solubilization fungi (PSF) has arisen as an eco-friendly strategy to increase this nutrient's bioavailability. The effect of PSF inoculation and its combination with P-transporting organisms (arbuscular mycorrhizal fungi, AMF) on plant growth has been previously studied. However, these studies did not evaluate the combined effect of PSF and AMF inoculation on plant growth, symbiosis, and soil quality. Therefore, the aim of this study is to assess the impact of PSF on the AMF-wheat symbiosis establishment and efficiency, considering the effect on plant growth and soil quality. We performed a greenhouse experiment with wheat under different treatments (+/-AMF: Rhizophagus irregularis; +/-PSF strains: Talaromyces flavus, T. helicus L7B, T. helicus N24, and T. diversus) and measured plant growth, AMF root colonization, symbiotic efficiency, and soil quality indicators. No interaction between PSF and R. irregularis was found in wheat growth, showcasing that their combination is not better than single inoculation. T. helicus strains did not interfere with the AMF-wheat symbiosis establishment, while T. diversus and T. flavus decreased it. The symbiotic efficiency was increased by T. flavus and T. helicus N24, and unchanged with T. helicus L7B and T. diversus inoculation. The soil quality indicators were higher with microbial co-inoculation, particularly the alkaline phosphatases parameter, showing the beneficial role of fungi in soil. This work highlights the importance of microbial interactions in the rhizosphere for crop sustainability and soil quality improvement, assessing the effects of PSF on AMF-wheat symbiosis.

RevDate: 2019-06-20

Otani S, Challinor VL, Kreuzenbeck NB, et al (2019)

Disease-free monoculture farming by fungus-growing termites.

Scientific reports, 9(1):8819 pii:10.1038/s41598-019-45364-z.

Fungus-growing termites engage in an obligate mutualistic relationship with Termitomyces fungi, which they maintain in monocultures on specialised fungus comb structures, without apparent problems with infectious diseases. While other fungi have been reported in the symbiosis, detailed comb fungal community analyses have been lacking. Here we use culture-dependent and -independent methods to characterise fungus comb mycobiotas from three fungus-growing termite species (two genera). Internal Transcribed Spacer (ITS) gene analyses using 454 pyrosequencing and Illumina MiSeq showed that non-Termitomyces fungi were essentially absent in fungus combs, and that Termitomyces fungal crops are maintained in monocultures as heterokaryons with two or three abundant ITS variants in a single fungal strain. To explore whether the essential absence of other fungi within fungus combs is potentially due to the production of antifungal metabolites by Termitomyces or comb bacteria, we performed in vitro assays and found that both Termitomyces and chemical extracts of fungus comb material can inhibit potential fungal antagonists. Chemical analyses of fungus comb material point to a highly complex metabolome, including compounds with the potential to play roles in mediating these contaminant-free farming conditions in the termite symbiosis.

RevDate: 2019-06-20

Shinohara A, Nohara M, Kondo Y, et al (2019)

Comparison of the gut microbiotas of laboratory and wild Asian house shrews (Suncus murinus) based on cloned 16S rRNA sequences.

Experimental animals [Epub ahead of print].

The Asian house shrew, Suncus murinus, is an insectivore (Eulipotyphla, Mammalia) and an important laboratory animal for life-science studies. The gastrointestinal tract of Suncus is simple: the length of the entire intestine is very short relative to body size, the large intestine is quite short, and there are no fermentative chambers such as the forestomach or cecum. These features imply that Suncus has a different nutritional physiology from those of humans and mice, but little is known about whether Suncus utilizes microbial fermentation in the large (LI) or small (SI) intestine. In addition, domestication may affect the gastrointestinal microbial diversity of Suncus. Therefore, we compared the gastrointestinal microbial diversity of Suncus between laboratory and wild Suncus and between the SI and LI (i.e., four groups: Lab-LI, Lab-SI, Wild-LI, and Wild-SI) using bacterial 16S rRNA gene library sequencing analyses with a sub-cloning method. We obtained 759 cloned sequences (176, 174, 195, and 214 from the Lab-LI, Lab-SI, Wild-LI, and Wild-SI samples, respectively), which revealed that the gastrointestinal microbiota of Suncus is rich in Firmicutes (mostly lactic acid bacteria), with few Bacteroidetes. We observed different bacterial communities according to intestinal region in laboratory Suncus, but not in wild Suncus. Furthermore, the gastrointestinal microbial diversity estimates were lower in laboratory Suncus than in wild Suncus. These results imply that Suncus uses lactic acid fermentation in the gut, and that the domestication process altered the gastrointestinal bacterial diversity.

RevDate: 2019-06-20
CmpDate: 2019-06-20

Vizentin-Bugoni J, Tarwater CE, Foster JT, et al (2019)

Structure, spatial dynamics, and stability of novel seed dispersal mutualistic networks in Hawai'i.

Science (New York, N.Y.), 364(6435):78-82.

Increasing rates of human-caused species invasions and extinctions may reshape communities and modify the structure, dynamics, and stability of species interactions. To investigate how such changes affect communities, we performed multiscale analyses of seed dispersal networks on O'ahu, Hawai'i. Networks consisted exclusively of novel interactions, were largely dominated by introduced species, and exhibited specialized and modular structure at local and regional scales, despite high interaction dissimilarity across communities. Furthermore, the structure and stability of the novel networks were similar to native-dominated communities worldwide. Our findings suggest that shared evolutionary history is not a necessary process for the emergence of complex network structure, and interaction patterns may be highly conserved, regardless of species identity and environment. Introduced species can quickly become well integrated into novel networks, making restoration of native ecosystems more challenging than previously thought.

RevDate: 2019-06-20
CmpDate: 2019-06-20

Couradeau E, Giraldo-Silva A, De Martini F, et al (2019)

Spatial segregation of the biological soil crust microbiome around its foundational cyanobacterium, Microcoleus vaginatus, and the formation of a nitrogen-fixing cyanosphere.

Microbiome, 7(1):55 pii:10.1186/s40168-019-0661-2.

BACKGROUND: Biological soil crusts (biocrusts) are a key component of arid land ecosystems, where they render critical services such as soil surface stabilization and nutrient fertilization. The bundle-forming, filamentous, non-nitrogen-fixing cyanobacterium Microcoleus vaginatus is a pioneer primary producer, often the dominant member of the biocrust microbiome, and the main source of leaked organic carbon. We hypothesized that, by analogy to the rhizosphere of plant roots, M. vaginatus may shape the microbial populations of heterotrophs around it, forming a specialized cyanosphere.

RESULTS: By physically isolating bundles of M. vaginatus from biocrusts, we were able to study the composition of the microbial populations attached to it, in comparison to the bulk soil crust microbiome by means of high-throughput 16S rRNA sequencing. We did this in two M. vaginatus-dominated biocrust from distinct desert biomes. We found that a small, selected subset of OTUs was significantly enriched in close proximity to M. vaginatus. Furthermore, we also found that a majority of bacteria (corresponding to some two thirds of the reads) were significantly more abundant away from this cyanobacterium. Phylogenetic placements suggest that all typical members of the cyanosphere were copiotrophs and that many were diazotrophs (Additional file 1: Tables S2 and S3). Nitrogen fixation genes were in fact orders of magnitude more abundant in this cyanosphere than in the bulk biocrust soil as assessed by qPCR. By contrary, competition for light, CO2, and low organic carbon concentrations defined at least a part of the OTUs segregating from the cyanobacterium.

CONCLUSIONS: We showed that M. vaginatus acts as a significant spatial organizer of the biocrust microbiome. On the one hand, it possesses a compositionally differentiated cyanosphere that concentrates the nitrogen-fixing function. We propose that a mutualism based on C for N exchange between M. vaginatus and copiotrophic diazotrophs helps sustains this cyanosphere and that this consortium constitutes the true pioneer community enabling the colonization of nitrogen-poor soils. On the other hand, a large number of biocrust community members segregate away from the vicinity of M. vaginatus, potentially through competition for light or CO2, or because of a preference for oligotrophy.

RevDate: 2019-06-20
CmpDate: 2019-06-20

Berglund F, Österlund T, Boulund F, et al (2019)

Identification and reconstruction of novel antibiotic resistance genes from metagenomes.

Microbiome, 7(1):52 pii:10.1186/s40168-019-0670-1.

BACKGROUND: Environmental and commensal bacteria maintain a diverse and largely unknown collection of antibiotic resistance genes (ARGs) that, over time, may be mobilized and transferred to pathogens. Metagenomics enables cultivation-independent characterization of bacterial communities but the resulting data is noisy and highly fragmented, severely hampering the identification of previously undescribed ARGs. We have therefore developed fARGene, a method for identification and reconstruction of ARGs directly from shotgun metagenomic data.

RESULTS: fARGene uses optimized gene models and can therefore with high accuracy identify previously uncharacterized resistance genes, even if their sequence similarity to known ARGs is low. By performing the analysis directly on the metagenomic fragments, fARGene also circumvents the need for a high-quality assembly. To demonstrate the applicability of fARGene, we reconstructed β-lactamases from five billion metagenomic reads, resulting in 221 ARGs, of which 58 were previously not reported. Based on 38 ARGs reconstructed by fARGene, experimental verification showed that 81% provided a resistance phenotype in Escherichia coli. Compared to other methods for detecting ARGs in metagenomic data, fARGene has superior sensitivity and the ability to reconstruct previously unknown genes directly from the sequence reads.

CONCLUSIONS: We conclude that fARGene provides an efficient and reliable way to explore the unknown resistome in bacterial communities. The method is applicable to any type of ARGs and is freely available via GitHub under the MIT license.

RevDate: 2019-06-20
CmpDate: 2019-06-20

Dale C (2017)

Evolution: Weevils Get Tough on Symbiotic Tyrosine.

Current biology : CB, 27(23):R1282-R1284.

Weevils, which represent one of the most diverse groups of terrestrial insects in nature, obtain a tough exoskeleton through the activity of an ancient bacterial symbiont with a tiny genome that serves as a factory for the production of tyrosine.

RevDate: 2019-06-20
CmpDate: 2019-06-20

Petitjean C, TA Williams (2017)

Evolution: New Gene-Rich Mitochondria Found across the Eukaryotic Tree.

Current biology : CB, 27(23):R1270-R1271.

Mitochondria are the energy-generating organelles that power eukaryotic cells. Originally descended from endosymbiotic bacteria, their genomes have shrunk during evolution. New analyses suggest that large, gene-rich mitochondrial genomes are more common than previously thought, with interesting implications for eukaryotic genome evolution.

RevDate: 2019-06-20
CmpDate: 2019-06-20

Archibald JM (2017)

Evolution: Protein Import in a Nascent Photosynthetic Organelle.

Current biology : CB, 27(18):R1004-R1006.

An amoeba named Paulinella harbours 'chromatophores', cyanobacterium-derived photosynthetic bodies that evolved independent of plastids. Proteomics has shown that hundreds of nucleus-encoded proteins are targeted to the chromatophore, revealing the host cell's contributions to its recently established organelle.

RevDate: 2019-06-19

Sieber M, Pita L, Weiland-Bräuer N, et al (2019)

Neutrality in the Metaorganism.

PLoS biology, 17(6):e3000298 pii:PBIOLOGY-D-18-00420.

Almost all animals and plants are inhabited by diverse communities of microorganisms, the microbiota, thereby forming an integrated entity, the metaorganism. Natural selection should favor hosts that shape the community composition of these microbes to promote a beneficial host-microbe symbiosis. Indeed, animal hosts often pose selective environments, which only a subset of the environmentally available microbes are able to colonize. How these microbes assemble after colonization to form the complex microbiota is less clear. Neutral models are based on the assumption that the alternatives in microbiota community composition are selectively equivalent and thus entirely shaped by random population dynamics and dispersal. Here, we use the neutral model as a null hypothesis to assess microbiata composition in host organisms, which does not rely on invoking any adaptive processes underlying microbial community assembly. We show that the overall microbiota community structure from a wide range of host organisms, in particular including previously understudied invertebrates, is in many cases consistent with neutral expectations. Our approach allows to identify individual microbes that are deviating from the neutral expectation and are therefore interesting candidates for further study. Moreover, using simulated communities, we demonstrate that transient community states may play a role in the deviations from the neutral expectation. Our findings highlight that the consideration of neutral processes and temporal changes in community composition are critical for an in-depth understanding of microbiota-host interactions.

RevDate: 2019-06-19

Plett K, Raposo AE, Anderson IC, et al (2019)

Protein arginine methyltransferase expression affects ectomycorrhizal symbiosis and the regulation of hormone signaling pathways.

Molecular plant-microbe interactions : MPMI [Epub ahead of print].

The genomes of all eukaryotic organisms, from small unicellular yeasts to humans, include members of the protein arginine methyltransferase (PRMT) family. These enzymes affect gene transcription, cellular signaling and function through the post-translational methylation of arginine residues. Mis-regulation of PRMTs results in serious developmental defects, disease or death, illustrating the importance of these enzymes to cellular processes. Plant genomes encode almost the full complement of PRMTs found in other higher organisms, plus an additional PRMT found uniquely in plants: PRMT10. Here we investigate the role of these highly conserved PRMTs in a process that is unique to perennial plants - the development of symbiosis with ectomycorrhizal fungi. We show that PRMT expression and arginine methylation is altered in the roots of the model tree Eucalyptus grandis by the presence of its ectomycorrhizal fungal symbiont Pisolithus albus. Further, using transgenic modifications, we demonstrate that E. grandis-encoded PRMT1 and PRMT10 have important, but opposing, effects in promoting this symbiosis. In particular, the plant specific EgPRMT10 has a potential role in the expression of plant hormone pathways during the colonization process and its over-expression reduces fungal colonization success.

RevDate: 2019-06-19

Page CE, Leggat W, Heron SF, et al (2019)

Seeking Resistance in Coral Reef Ecosystems: The Interplay of Biophysical Factors and Bleaching Resistance under a Changing Climate: The Interplay of a Reef's Biophysical Factors Can Mitigate the Coral Bleaching Response.

BioEssays : news and reviews in molecular, cellular and developmental biology [Epub ahead of print].

If we are to ensure the persistence of species in an increasingly warm world, of interest is the identification of drivers that affect the ability of an organism to resist thermal stress. Underpinning any organism's capacity for resistance is a complex interplay between biological and physical factors occurring over multiple scales. Tropical coral reefs are a unique system, in that their function is dependent upon the maintenance of a coral-algal symbiosis that is directly disrupted by increases in water temperature. A number of physical factors have been identified as affecting the biological responses of the coral organism under broadscale thermal anomalies. One such factor is water flow, which is capable of modulating both organismal metabolic functioning and thermal environments. Understanding the physiological and hydrodynamic drivers of organism response to thermal stress improves predictive capabilities and informs targeted management responses, thereby increasing the resilience of reefs into the future.

RevDate: 2019-06-19

Law SR (2019)

The genetic program at the root of the biological stock exchange.

Physiologia plantarum, 166(3):709-711.

Beneath the gardens, farmlands and forest floors that surround us, a hidden world blooms in careful cooperation and intense competition. The mutualistic symbiosis of the thread-like hyphae of fungi and plant roots (collectively termed mycorrhizae from the Greek mýkēs - meaning 'fungus', and rhiza - for 'root') is present in the vast majority of plant species. As with most intimate relationships, this symbiosis functions on a principle of 'give and take'. As an autotroph, the plant is able to synthesize all the sugars it requires through photosynthesis; however, its immobility hinders its capacity to forage for nutrients vital for its growth and survival. With an expansive network of hyphae, the heterotrophic fungus is able to locate and remobilize water and nutrients, such as phosphorus (P) and nitrogen (N), and barter them for precious sugars with the plant. An article in this issue of Physiologia Plantarum (Zhao et al. 2019) describes alterations in the genetic programming that takes place in the plant root upon the establishment of this fascinating relationship, which has profound implications for plant productivity and soil management methods.

RevDate: 2019-06-19

Phillips AJ, Dornburg A, Zapfe KL, et al (2019)

Phylogenomic Analysis of a Putative Missing Link Sparks Reinterpretation of Leech Evolution.

Genome biology and evolution pii:5520445 [Epub ahead of print].

Leeches (Hirudinida) comprise a charismatic, yet often maligned group of organisms. Despite their ecological, economic, and medical importance, a general consensus on the phylogenetic relationships of major hirudinidan lineages is lacking. This absence of a consistent, robust phylogeny of early-diverging lineages has hindered our understanding of the underlying processes that enabled evolutionary diversification of this clade. Here, we used an Anchored Hybrid Enrichment-based phylogenomic approach, capturing hundreds of loci to investigate phylogenetic relationships among major hirudinidan lineages and their closest living relatives. Our results suggest that a dramatic reinterpretation of early leech evolution is warranted. We recovered Branchiobdellida as sister to a clade that includes all major lineages of hirudinidans, but found Acanthobdella to be nested within Oceanobdelliformes. These results cast doubt on the utility of Acanthobdella as a 'missing link' used to explain the origin of blood-feeding in hirudineans. Further, our results support a deep divergence between predominantly marine and freshwater lineages, while not supporting the reciprocal monophyly of jawed and proboscis-bearing leeches. To sum up, our phylogenomic resolution of early-diverging leeches provides a necessary foundation for illuminating the evolution of host-symbiont associations and key adaptations that have allowed leeches to colonize a wide diversity of habitats worldwide.

RevDate: 2019-06-19

Billault-Penneteau B, Sandré A, Folgmann J, et al (2019)

Dryas as a Model for Studying the Root Symbioses of the Rosaceae.

Frontiers in plant science, 10:661.

The nitrogen-fixing root nodule symbiosis is restricted to four plant orders: Fabales (legumes), Fagales, Cucurbitales and Rosales (Elaeagnaceae, Rhamnaceae, and Rosaceae). Interestingly all of the Rosaceae genera confirmed to contain nodulating species (i.e., Cercocarpus, Chamaebatia, Dryas, and Purshia) belong to a single subfamily, the Dryadoideae. The Dryas genus is particularly interesting from an evolutionary perspective because it contains closely related nodulating (Dryas drummondii) and non-nodulating species (Dryas octopetala). The close phylogenetic relationship between these two species makes Dryas an ideal model genus to study the genetic basis of nodulation by whole genome comparison and classical genetics. Therefore, we established methods for plant cultivation, transformation and DNA extraction for these species. We optimized seed surface sterilization and germination methods and tested growth protocols ranging from pots and Petri dishes to a hydroponic system. Transgenic hairy roots were obtained by adapting Agrobacterium rhizogenes-based transformation protocols for Dryas species. We compared several DNA extraction protocols for their suitability for subsequent molecular biological analysis. Using CTAB extraction, reproducible PCRs could be performed, but CsCl gradient purification was essential to obtain DNA in sufficient purity for high quality de novo genome sequencing of both Dryas species. Altogether, we established a basic toolkit for the culture, transient transformation and genetic analysis of Dryas sp.

RevDate: 2019-06-19

Medrano E, Merselis DG, Bellantuono AJ, et al (2019)

Proteomic Basis of Symbiosis: A Heterologous Partner Fails to Duplicate Homologous Colonization in a Novel Cnidarian- Symbiodiniaceae Mutualism.

Frontiers in microbiology, 10:1153.

Reef corals and sea anemones form symbioses with unicellular symbiotic dinoflagellates. The molecular circumventions that underlie the successful intracellular colonization of hosts by symbionts are still largely unknown. We conducted proteomic analyses to determine molecular differences of Exaiptasia pallida anemones colonized by physiologically different symbiont species, in comparison with symbiont-free (aposymbiotic) anemones. We compared one homologous species, Symbiodinium linucheae, that is natively associated with the clonal Exaiptasia strain (CC7) to another heterologous species, Durusdinium trenchii, a thermally tolerant species that colonizes numerous coral species. This approach allowed the discovery of a core set of host genes that are differentially regulated as a function of symbiosis regardless of symbiont species. The findings revealed that symbiont colonization at higher densities requires circumvention of the host cellular immunological response, enhancement of ammonium regulation, and suppression of phagocytosis after a host cell in colonized. Furthermore, the heterologous symbionts failed to duplicate the same level of homologous colonization within the host, evidenced by substantially lower symbiont densities. This reduced colonization of D. trenchii correlated with its inability to circumvent key host systems including autophagy-suppressing modulators, cytoskeletal alteration, and isomerase activity. The larger capability of host molecular circumvention by homologous symbionts could be the result of a longer evolutionary history of host/symbiont interactions, which translates into a more finely tuned symbiosis. These findings are of great importance within the context of the response of reef corals to climate change since it has been suggested that coral may acclimatize to ocean warming by changing their dominant symbiont species.

RevDate: 2019-06-19

Van Leuven JT, Mao M, Xing DD, et al (2019)

Cicada Endosymbionts Have tRNAs That Are Correctly Processed Despite Having Genomes That Do Not Encode All of the tRNA Processing Machinery.

mBio, 10(3): pii:mBio.01950-18.

Gene loss and genome reduction are defining characteristics of endosymbiotic bacteria. The most highly reduced endosymbiont genomes have lost numerous essential genes related to core cellular processes such as replication, transcription, and translation. Computational gene predictions performed for the genomes of the two bacterial symbionts of the cicada Diceroprocta semicincta, "Candidatus Hodgkinia cicadicola" (Alphaproteobacteria) and "Ca Sulcia muelleri" (Bacteroidetes), have found only 26 and 16 tRNA genes and 15 and 10 aminoacyl tRNA synthetase genes, respectively. Furthermore, the original "Ca Hodgkinia cicadicola" genome annotation was missing several essential genes involved in tRNA processing, such as those encoding RNase P and CCA tRNA nucleotidyltransferase as well as several RNA editing enzymes required for tRNA maturation. How these cicada endosymbionts perform basic translation-related processes remains unknown. Here, by sequencing eukaryotic mRNAs and total small RNAs, we show that the limited tRNA set predicted by computational annotation of "Ca Sulcia muelleri" and "Ca Hodgkinia cicadicola" is likely correct. Furthermore, we show that despite the absence of genes encoding tRNA processing activities in the symbiont genomes, symbiont tRNAs have correctly processed 5' and 3' ends and seem to undergo nucleotide modification. Surprisingly, we found that most "Ca Hodgkinia cicadicola" and "Ca Sulcia muelleri" tRNAs exist as tRNA halves. We hypothesize that "Ca Sulcia muelleri" and "Ca Hodgkinia cicadicola" tRNAs function in bacterial translation but require host-encoded enzymes to do so.IMPORTANCE The smallest bacterial genomes, in the range of about 0.1 to 0.5 million base pairs, are commonly found in the nutritional endosymbionts of insects. These tiny genomes are missing genes that encode proteins and RNAs required for the translation of mRNAs, one of the most highly conserved and important cellular processes. In this study, we found that the bacterial endosymbionts of cicadas have genomes which encode incomplete tRNA sets and lack genes required for tRNA processing. Nevertheless, we found that endosymbiont tRNAs are correctly processed at their 5' and 3' ends and, surprisingly, that mostly exist as tRNA halves. We hypothesize that the cicada host must supply its symbionts with these missing tRNA processing activities.

RevDate: 2019-06-19
CmpDate: 2019-06-19

Mascuch S, J Kubanek (2019)

A marine chemical defense partnership.

Science (New York, N.Y.), 364(6445):1034-1035.

RevDate: 2019-06-19
CmpDate: 2019-06-19

Tanoue T, Morita S, Plichta DR, et al (2019)

A defined commensal consortium elicits CD8 T cells and anti-cancer immunity.

Nature, 565(7741):600-605.

There is a growing appreciation for the importance of the gut microbiota as a therapeutic target in various diseases. However, there are only a handful of known commensal strains that can potentially be used to manipulate host physiological functions. Here we isolate a consortium of 11 bacterial strains from healthy human donor faeces that is capable of robustly inducing interferon-γ-producing CD8 T cells in the intestine. These 11 strains act together to mediate the induction without causing inflammation in a manner that is dependent on CD103+ dendritic cells and major histocompatibility (MHC) class Ia molecules. Colonization of mice with the 11-strain mixture enhances both host resistance against Listeria monocytogenes infection and the therapeutic efficacy of immune checkpoint inhibitors in syngeneic tumour models. The 11 strains primarily represent rare, low-abundance components of the human microbiome, and thus have great potential as broadly effective biotherapeutics.

RevDate: 2019-06-19
CmpDate: 2019-06-19

Barfield SJ, Aglyamova GV, Bay LK, et al (2018)

Contrasting effects of Symbiodinium identity on coral host transcriptional profiles across latitudes.

Molecular ecology, 27(15):3103-3115.

Reef-building corals can increase their resistance to heat-induced bleaching through adaptation and acclimatization and/or by associating with a more thermo-tolerant strain of algal symbiont (Symbiodinium sp.). Here, we show that these two adaptive pathways interact. We collected Acropora millepora corals from two contrasting thermal environments on the Great Barrier Reef: cooler, mid-latitude Orpheus Island, where all corals hosted a heat-sensitive clade C Symbiodinium, and warmer, low-latitude Wilkie Island, where corals hosted either a clade C or a more thermo-tolerant clade D. Corals were kept in a benign common garden to reveal differences in baseline gene expression, reflecting prior adaptation/long-term acclimatization. Model-based analysis identified gene expression differences between Wilkie and Orpheus corals that were negatively correlated with previously described transcriptome-wide signatures of heat stress, signifying generally elevated thermotolerance of Wilkie corals. Yet, model-free analyses of gene expression revealed that Wilkie corals hosting clade C were distinct from Wilkie corals hosting clade D, whereas Orpheus corals were more variable. Wilkie corals hosting clade C symbionts exhibited unique functional signatures, including downregulation of histone proteins and ion channels and upregulation of chaperones and RNA processing genes, putatively representing constitutive "frontloading" of stress response genes. Furthermore, clade C Symbiodinium exhibited constitutive expression differences between Wilkie and Orpheus, indicative of contrasting life history strategies. Our results demonstrate that hosting alternative Symbiodinium types is associated with different pathways of local adaptation for the coral host. These interactions could play a significant role in setting the direction of genetic adaptation to global warming in the two symbiotic partners.

RevDate: 2019-06-19
CmpDate: 2019-06-19

de Vries J, JM Archibald (2017)

Endosymbiosis: Did Plastids Evolve from a Freshwater Cyanobacterium?.

Current biology : CB, 27(3):R103-R105.

Photosynthetic eukaryotes are the product of an endosymbiotic event between a eukaryotic host and a cyanobacterium that became today's plastid. A new phylogenomic study suggests that the closest relative of plastids among extant cyanobacteria is the recently discovered freshwater-dwelling Gloeomargarita lithophora.

RevDate: 2019-06-18

Müller LM, MJ Harrison (2019)

Phytohormones, miRNAs, and peptide signals integrate plant phosphorus status with arbuscular mycorrhizal symbiosis.

Current opinion in plant biology, 50:132-139 pii:S1369-5266(18)30106-7 [Epub ahead of print].

Most land plant species engage in a beneficial interaction with arbuscular mycorrhizal fungi in order to increase mineral nutrient acquisition, in particular the major macronutrient phosphorus (P). Initiation, development, and maintenance of the symbiosis are largely under the control of the host plant and strongly influenced by the plants' P status. Recent advances reveal that phytohormones, microRNAs, and secreted peptides all regulate and integrate development of arbuscular mycorrhizal (AM) symbiosis with the P status of the plant. This occurs through a complex, multi-layered signaling network with crosstalk between phosphate (Pi) starvation signaling pathways and AM symbiosis signaling, and also via direct effects on the AM fungal symbiont. Multiple checkpoints allow the plant to fine-tune symbiosis based on its P status.

RevDate: 2019-06-18

McCutcheon JP, Y Lekberg (2019)

Symbiosis: Fungi as Shrewd Trade Negotiators.

Current biology : CB, 29(12):R570-R572.

Symbiotic fungi associated with plant roots can shuttle a key nutrient through their hyphal network in response to resource inequality. This need-based transport optimizes trade conditions for carbon with plants.

RevDate: 2019-06-18

Cui C, Wang H, Hong L, et al (2019)

MtBZR1 Plays an Important Role in Nodule Development in Medicago truncatula.

International journal of molecular sciences, 20(12): pii:ijms20122941.

Brassinosteroid (BR) is an essential hormone in plant growth and development. The BR signaling pathway was extensively studied, in which BRASSINAZOLE RESISTANT 1 (BZR1) functions as a key regulator. Here, we carried out a functional study of the homolog of BZR1 in Medicago truncatula R108, whose expression was induced in nodules upon Sinorhizobium meliloti 1021 inoculation. We identified a loss-of-function mutant mtbzr1-1 and generated 35S:MtBZR1 transgenic lines for further analysis at the genetic level. Both the mutant and the overexpression lines of MtBZR1 showed no obvious phenotypic changes under normal growth conditions. After S. meliloti 1021 inoculation, however, the shoot and root dry mass was reduced in mtbzr1-1 compared with the wild type, caused by partially impaired nodule development. The transcriptomic analysis identified 1319 differentially expressed genes in mtbzr1-1 compared with wild type, many of which are involved in nodule development and secondary metabolite biosynthesis. Our results demonstrate the role of MtBZR1 in nodule development in M. truncatula, shedding light on the potential role of BR in legume-rhizobium symbiosis.

RevDate: 2019-06-18

Dominguez H, EP Loret (2019)

Ulva lactuca, A Source of Troubles and Potential Riches.

Marine drugs, 17(6): pii:md17060357.

Ulva lactuca is a green macro alga involved in devastating green tides observed worldwide. These green tides or blooms are a consequence of human activities. Ulva blooms occur mainly in shallow waters and the decomposition of this alga can produce dangerous vapors. Ulva lactuca is a species usually resembling lettuce, but genetic analyses demonstrated that other green algae with tubular phenotypes were U. lactuca clades although previously described as different species or even genera. The capacity for U. lactuca to adopt different phenotypes can be due to environment parameters, such as the degree of water salinity or symbiosis with bacteria. No efficient ways have been discovered to control these green tides, but the Mediterranean seas appear to be protected from blooms, which disappear rapidly in springtime. Ulva contains commercially valuable components, such as bioactive compounds, food or biofuel. The biomass due to this alga collected on beaches every year is beginning to be valorized to produce valuable compounds. This review describes different processes and strategies developed to extract these different valuable components.

RevDate: 2019-06-18

Onchuru TO, M Kaltenpoth (2019)

Established Cotton Stainer Gut Bacterial Mutualists Evade Regulation by Host Antimicrobial Peptides.

Applied and environmental microbiology, 85(13): pii:AEM.00738-19.

Symbioses with microorganisms are ubiquitous in nature and confer important ecological traits to animal hosts but also require control mechanisms to ensure homeostasis of the symbiotic interactions. In addition to protecting hosts against pathogens, animal immune systems recognize, respond to, and regulate mutualists. The gut bacterial symbionts of the cotton stainer bug, Dysdercus fasciatus, elicit an immune response characterized by the upregulation of c-type lysozyme and the antimicrobial peptide pyrrhocoricin in bugs with their native gut microbiota compared to that in dysbiotic insects. In this study, we investigated the impact of the elicited antimicrobial immune response on the established cotton stainer gut bacterial symbiont populations. To this end, we used RNA interference (RNAi) to knock down immunity-related genes hypothesized to regulate the symbionts, and we subsequently measured the effect of this silencing on host fitness and on the abundance of the major gut bacterial symbionts. Despite successful downregulation of target genes by both ingestion and injection of double-stranded RNA (dsRNA), the silencing of immunity-related genes had no effect on either host fitness or the qualitative and quantitative composition of established gut bacterial symbionts, indicating that the host immune responses are not actively involved in the regulation of the nutritional and defensive gut bacterial mutualists. These results suggest that close associations of bacterial symbionts with their hosts can result in the evolution of mechanisms ensuring that symbionts remain insensitive to host immunological responses, which may be important for the evolutionary stability of animal-microbe symbiotic associations.IMPORTANCE Animal immune systems are central for the protection of hosts against enemies by preventing or eliminating successful infections. However, in the presence of beneficial bacterial mutualists, the immune system must strike a balance of not killing the beneficial symbionts while at the same time preventing enemy attacks. Here, using the cotton stainer bug, we reveal that its long-term associated bacterial symbionts are insensitive to the host's immune effectors, suggesting adaptation to the host's defenses, thereby strengthening the stability of the symbiotic relationship. The ability of the symbionts to elicit host immune responses but remain insensitive themselves may be a mechanism by which the symbionts prime hosts to fight future pathogenic infections.

RevDate: 2019-06-18
CmpDate: 2019-06-18

Marcionetti A, Rossier V, Roux N, et al (2019)

Insights into the Genomics of Clownfish Adaptive Radiation: Genetic Basis of the Mutualism with Sea Anemones.

Genome biology and evolution, 11(3):869-882.

Clownfishes are an iconic group of coral reef fishes, especially known for their mutualism with sea anemones. This mutualism is particularly interesting as it likely acted as the key innovation that triggered clownfish adaptive radiation. Indeed, after the acquisition of the mutualism, clownfishes diversified into multiple ecological niches linked with host and habitat use. However, despite the importance of this mutualism, the genetic mechanisms allowing clownfishes to interact with sea anemones are still unclear. Here, we used a comparative genomics and molecular evolutionary analyses to investigate the genetic basis of clownfish mutualism with sea anemones. We assembled and annotated the genome of nine clownfish species and one closely related outgroup. Orthologous genes inferred between these species and additional publicly available teleost genomes resulted in almost 16,000 genes that were tested for positively selected substitutions potentially involved in the adaptation of clownfishes to live in sea anemones. We identified 17 genes with a signal of positive selection at the origin of clownfish radiation. Two of them (Versican core protein and Protein O-GlcNAse) show particularly interesting functions associated with N-acetylated sugars, which are known to be involved in sea anemone discharge of toxins. This study provides the first insights into the genetic mechanisms of clownfish mutualism with sea anemones. Indeed, we identified the first candidate genes likely to be associated with clownfish protection form sea anemones, and thus the evolution of their mutualism. Additionally, the genomic resources acquired represent a valuable resource for further investigation of the genomic basis of clownfish adaptive radiation.

RevDate: 2019-06-18
CmpDate: 2019-06-18

Pizarro D, Dal Grande F, Leavitt SD, et al (2019)

Whole-Genome Sequence Data Uncover Widespread Heterothallism in the Largest Group of Lichen-Forming Fungi.

Genome biology and evolution, 11(3):721-730.

Fungal reproduction is regulated by the mating-type (MAT1) locus, which typically comprises two idiomorphic genes. The presence of one or both allelic variants at the locus determines the reproductive strategy in fungi-homothallism versus heterothallism. It has been hypothesized that self-fertility via homothallism is widespread in lichen-forming fungi. To test this hypothesis, we characterized the MAT1 locus of 41 genomes of lichen-forming fungi representing a wide range of growth forms and reproductive strategies in the class Lecanoromycetes, the largest group of lichen-forming fungi. Our results show the complete lack of genetic homothallism suggesting that lichens evolved from a heterothallic ancestor. We argue that this may be related to the symbiotic lifestyle of these fungi, and may be a key innovation that has contributed to the accelerated diversification rates in this fungal group.

RevDate: 2019-06-18
CmpDate: 2019-06-18

Irwin NAT, PJ Keeling (2019)

Extensive Reduction of the Nuclear Pore Complex in Nucleomorphs.

Genome biology and evolution, 11(3):678-687.

The nuclear pore complex (NPC) is a large macromolecular assembly situated within the pores of the nuclear envelope. Through interactions between its subcomplexes and import proteins, the NPC mediates the transport of molecules into and out of the nucleus and facilitates dynamic chromatin regulation and gene expression. Accordingly, the NPC constitutes a highly integrated nuclear component that is ubiquitous and conserved among eukaryotes. Potential exceptions to this are nucleomorphs: Highly reduced, relict nuclei that were derived from green and red algae following their endosymbiotic integration into two lineages, the chlorarachniophytes and the cryptophyceans. A previous investigation failed to identify NPC genes in nucleomorph genomes suggesting that these genes have either been relocated to the host nucleus or lost. Here, we sought to investigate the composition of the NPC in nucleomorphs by using genomic and transcriptomic data to identify and phylogenetically classify NPC proteins in nucleomorph-containing algae. Although we found NPC proteins in all examined lineages, most of those found in chlorarachniophytes and cryptophyceans were single copy, host-related proteins that lacked signal peptides. Two exceptions were Nup98 and Rae1, which had clear nucleomorph-derived homologs. However, these proteins alone are likely insufficient to structure a canonical NPC and previous reports revealed that Nup98 and Rae1 have other nuclear functions. Ultimately, these data indicate that nucleomorphs represent eukaryotic nuclei without a canonical NPC, raising fundamental questions about their structure and function.

RevDate: 2019-06-18
CmpDate: 2019-06-18

Taylor MJ, Bordenstein SR, B Slatko (2018)

Microbe Profile: Wolbachia: a sex selector, a viral protector and a target to treat filarial nematodes.

Microbiology (Reading, England), 164(11):1345-1347.

Wolbachia is the most widespread genus of endosymbiotic bacteria in the animal world, infecting a diverse range of arthropods and nematodes. A broad spectrum of associations from parasitism to mutualism occur, with a tendency to drive reproductive manipulation or influence host fecundity to spread infection through host populations. These varied effects of Wolbachia are exploited for public health benefits. Notably, the protection of insect hosts from viruses is being tested as a potential control strategy for human arboviruses, and the mutualistic relationship with filarial nematodes makes Wolbachia a target for antibiotic therapy of human and veterinary nematode diseases.

RevDate: 2019-06-17

Zou H, Zhang NN, Pan Q, et al (2019)

Hydrogen Sulfide Promotes Nodulation and Nitrogen Fixation in Soybean-Rhizobia Symbiotic System.

Molecular plant-microbe interactions : MPMI [Epub ahead of print].

The rhizobium-legume symbiotic system is crucial for nitrogen cycle balance in agriculture. Hydrogen sulfide (H2S), a gaseous signaling molecule, may regulate various physiological processes in plants. However, whether H2S has regulatory effect in this symbiotic system remains unknown. Herein, we investigated the possible role of H2S in the symbiosis between soybean (Glycine max) and rhizobium (Sinorhizobium fredii). Our results demonstrated that an exogenous H2S donor (sodium hydrosulfide [NaHS]) treatment promoted soybean growth, nodulation, and nitrogenase (Nase) activity. Western blotting analysis revealed that the abundance of Nase component nifH was increased by NaHS treatment in nodules. Quantitative real-time polymerase chain reaction data showed that NaHS treatment upregulated the expressions of symbiosis-related genes nodA, nodC, and nodD of S. fredii. In addition, expression of soybean nodulation marker genes, including early nodulin 40 (GmENOD40), ERF required for nodulation (GmERN), nodulation signaling pathway 2b (GmNSP2b), and nodulation inception genes (GmNIN1a, GmNIN2a, and GmNIN2b), were upregulated. Moreover, the expressions of glutamate synthase (GmGOGAT), asparagine synthase (GmAS), nitrite reductase (GmNiR), ammonia transporter (GmSAT1), leghemoglobin (GmLb), and nifH involved in nitrogen metabolism were upregulated in NaHS-treated soybean roots and nodules. Together, our results suggested that H2S may act as a positive signaling molecule in the soybean-rhizobia symbiotic system and enhance the system's nitrogen fixation ability.

RevDate: 2019-06-17

Ravindran S, Tambe AJ, Suthar JK, et al (2019)

Nanomedicine: Bioavailability, Biotransformation and Biokinetics.

Current drug metabolism pii:CDM-EPUB-98815 [Epub ahead of print].

BACKGROUND: Nanomedicine is increasingly used to treat various ailments. Biocompatibility of nanomedicine is primarily governed by its properties such as bioavailability, biotransformation, and biokinetics. One of the major advantages of nanomedicine is the enhanced bioavailability of drugs. Biotransformation of nanomedicine is important to understand the pharmacological effects of nanomedicine. Biokinetics includes both pharmacokinetics and toxicokinetics of nanomedicine. Physicochemical parameters of nanomaterials have extensive influence on bioavailability, biotransformation, and biokinetics of nanomedicine.

METHOD: We carried out a structured peer-reviewed research literature survey and analysis using bibliographic databases.

RESULTS: Seventy-nine papers were included in the review. Papers dealing with bioavailability, biotransformation, and biokinetics of nanomedicine are found and reviewed. Bioavailability and biotransformation along with biokinetics are three major factors that determine the biological fate of nanomedicine. Extensive research work has been done for drugs of micron size but studies on nanomedicine are scarce. Therefore, more emphasis in this review is given on bioavailability and biotransformation of nanomedicine along with biokinetics.

CONCLUSION: Bioavailability results based on various nanomedicine are summarized in the present work. Biotransformation of nanodrugs, as well as nanoformulations, is also the focus of this article. Both in vitro and in vivo biotransformation studies on nanodrugs and its excipients are necessary to know the effect of metabolites formed. Biokinetics of nanomedicine is captured in details that are complementary to bioavailability and biotransformation. Nanomedicine has the potential to be developed as a personalized medicine once its physicochemical properties and its effect on biological system is well understood.

RevDate: 2019-06-17
CmpDate: 2019-06-17

Bell TJ, Draper SL, Centanni M, et al (2018)

Characterization of Polysaccharides from Feijoa Fruits (Acca sellowiana Berg.) and Their Utilization as Growth Substrates by Gut Commensal Bacteroides Species.

Journal of agricultural and food chemistry, 66(50):13277-13284.

Polysaccharides from feijoa fruit were extracted and analyzed; the composition of these polysaccharides conforms to those typically found in the primary cell walls of eudicotyledons. The two major polysaccharide extracts consisted of mainly pectic polysaccharides and hemicellulosic polysaccharides [xyloglucan (77%) and arabinoxylan (16%)]. A collection of commensal Bacteroides species was screened for growth in culture using these polysaccharide preparations and placed into five categories based on their preference for each substrate. Most of the species tested could utilize the pectic polysaccharides, but growth on the hemicellulose was more limited. Constituent sugar and glycosyl linkage analysis showed that species that grew on the hemicellulose fraction showed differences in their preference for the two polysaccharides in this preparation. Our data demonstrate that the members of the genus Bacteroides show differential hydrolysis of pectic polysaccharides, xyloglucan, and arabinoxylan, which might influence the structure and metabolic activities of the microbiota in the human gut.

RevDate: 2019-06-17
CmpDate: 2019-06-17

Sigwart JD, C Chen (2018)

Comparative Oxygen Consumption of Gastropod Holobionts from Deep-Sea Hydrothermal Vents in the Indian Ocean.

The Biological bulletin, 235(2):102-112.

Physiological traits are the foundation of an organism's success in a dynamic environment, yet basic measurements are unavailable for many taxa and even ecosystems. We measured routine metabolism in two hydrothermal vent gastropods, Alviniconcha marisindica (n = 40) and the scaly-foot gastropod Chrysomallon squamiferum (n = 18), from Kairei and Edmond vent fields on the Central Indian Ridge (23-25°S, about 3000 meter depth). No previous studies have measured metabolism in any Indian Ocean vent animals. After recovering healthy animals to the surface, we performed shipboard closed-chamber respirometry experiments to compare oxygen uptake at different temperatures (10, 16, and 25 °C) at surface pressure (1 atm). The physiology of these species is driven by the demands of their chemoautotrophic symbionts. Chrysomallon has very enlarged respiratory and circulatory systems, and endosymbionts are housed in its trophosome-like internal esophageal gland. By contrast, Alviniconcha has chemoautotrophic bacteria within the gill and less extensive associated anatomical adaptations. Thus, we predicted that routine oxygen consumption of Chrysomallon might be higher than that of Alviniconcha. However, oxygen consumption of Chrysomallon was not higher than that of Alviniconcha, and, further, Chrysomallon maintained a steady metabolic demand in two widely separated experimental temperatures, while Alviniconcha did not. We interpret that these findings indicate that (1) the "trophosome" does not fundamentally increase oxygen requirement compared to other gastropod holobionts, and (2) cold temperatures (10 °C) induce a stress response in Alviniconcha, resulting in aberrantly high uptake. While these two large gastropod species co-occur, differences in oxygen consumption may reflect the separate niches they occupy in the vent ecosystem.

RevDate: 2019-06-17
CmpDate: 2019-06-17

Burke GR, Simmonds TJ, Sharanowski BJ, et al (2018)

Rapid Viral Symbiogenesis via Changes in Parasitoid Wasp Genome Architecture.

Molecular biology and evolution, 35(10):2463-2474.

Viral genome integration provides a complex route to biological innovation that has rarely but repeatedly occurred in one of the most diverse lineages of organisms on the planet, parasitoid wasps. We describe a novel endogenous virus in braconid wasps derived from pathogenic alphanudiviruses. Limited to a subset of the genus Fopius, this recent acquisition allows an unprecedented opportunity to examine early endogenization events. Massive amounts of virus-like particles (VLPs) are produced in wasp ovaries. Unlike most endogenous viruses of parasitoid wasps, the VLPs do not contain DNA, translating to major differences in parasitism-promoting strategies. Rapid changes include genomic rearrangement, loss of DNA processing proteins, and wasp control of viral gene expression. These events precede the full development of tissue-specific viral gene expression observed in older associations. These data indicate that viral endogenization can rapidly result in functional and evolutionary changes associated with genomic novelty and adaptation in parasitoids.

RevDate: 2019-06-17
CmpDate: 2019-06-17

van Oppen MJH, Bongaerts P, Frade P, et al (2018)

Adaptation to reef habitats through selection on the coral animal and its associated microbiome.

Molecular ecology, 27(14):2956-2971.

Spatially adjacent habitats on coral reefs can represent highly distinct environments, often harbouring different coral communities. Yet, certain coral species thrive across divergent environments. It is unknown whether the forces of selection are sufficiently strong to overcome the counteracting effects of the typically high gene flow over short distances, and for local adaptation to occur. We screened the coral genome (using restriction site-associated sequencing) and characterized both the dinoflagellate photosymbiont- and tissue-associated prokaryote microbiomes (using metabarcoding) of a reef flat and slope population of the reef-building coral, Pocillopora damicornis, at two locations on Heron Island in the southern Great Barrier Reef. Reef flat and slope populations were separated by <100 m horizontally and ~5 m vertically, and the two study locations were separated by ~1 km. For the coral host, genetic divergence between habitats was much greater than between locations, suggesting limited gene flow between the flat and slope populations. Consistent with environmental selection, outlier loci primarily belonged to the conserved, minimal cellular stress response, likely reflecting adaptation to the different temperature and irradiance regimes on the reef flat and slope. The prokaryote community differed across both habitat and, to a lesser extent, location, whereas the dinoflagellate photosymbionts differed by habitat but not location. The observed intraspecific diversity associated with divergent habitats supports that environmental adaptation involves multiple members of the coral holobiont. Adaptive alleles or microbial associations present in coral populations from the environmentally variable reef flat may provide a source of adaptive variation for assisted evolution approaches, through assisted gene flow, artificial cross-breeding or probiotic inoculations, with the aim to increase climate resilience in the slope populations.

RevDate: 2019-06-17
CmpDate: 2019-06-17

Zúñiga A, Fuente F, Federici F, et al (2018)

An Engineered Device for Indoleacetic Acid Production under Quorum Sensing Signals Enables Cupriavidus pinatubonensis JMP134 To Stimulate Plant Growth.

ACS synthetic biology, 7(6):1519-1527.

The environmental effects of chemical fertilizers and pesticides have encouraged the quest for new strategies to increase crop productivity with minimal impacts on the natural medium. Plant growth promoting rhizobacteria (PGPR) can contribute to this endeavor by improving fitness through better nutrition acquisition and stress tolerance. Using the neutral (non PGPR) rhizobacterium Cupriavidus pinatubonensis JMP134 as the host, we engineered a regulatory forward loop that triggered the synthesis of the phytohormone indole-3-acetic acid (IAA) in a manner dependent on quorum sensing (QS) signals. Implementation of the device in JMP134 yielded synthesis of IAA in an autoregulated manner, improving the growth of the roots of inoculated Arabidopsis thaliana. These results not only demonstrated the value of the designed genetic module, but also validated C. pinatubonensis JMP134 as a suitable vehicle for agricultural applications, as it is amenable to genetic manipulations.

RevDate: 2019-06-17
CmpDate: 2019-06-17

Chen Y, Chaudhary N, Yang N, et al (2018)

Microbial symbionts regulate the primary Ig repertoire.

The Journal of experimental medicine, 215(5):1397-1415.

The ability of immunoglobulin (Ig) to recognize pathogens is critical for optimal immune fitness. Early events that shape preimmune Ig repertoires, expressed on IgM+ IgD+ B cells as B cell receptors (BCRs), are poorly defined. Here, we studied germ-free mice and conventionalized littermates to explore the hypothesis that symbiotic microbes help shape the preimmune Ig repertoire. Ig-binding assays showed that exposure to conventional microbial symbionts enriched frequencies of antibacterial IgM+ IgD+ B cells in intestine and spleen. This enrichment affected follicular B cells, involving a diverse set of Ig-variable region gene segments, and was T cell-independent. Functionally, enrichment of microbe reactivity primed basal levels of small intestinal T cell-independent, symbiont-reactive IgA and enhanced systemic IgG responses to bacterial immunization. These results demonstrate that microbial symbionts influence host immunity by enriching frequencies of antibacterial specificities within preimmune B cell repertoires and that this may have consequences for mucosal and systemic immunity.

RevDate: 2019-06-17
CmpDate: 2019-06-17

Miller JH, Field JJ, Kanakkanthara A, et al (2018)

Marine Invertebrate Natural Products that Target Microtubules.

Journal of natural products, 81(3):691-702.

Marine natural products as secondary metabolites are a potential major source of new drugs for treating disease. In some cases, cytotoxic marine metabolites target the microtubules of the eukaryote cytoskeleton for reasons that will be discussed. This review covers the microtubule-targeting agents reported from sponges, corals, tunicates, and molluscs and the evidence that many of these secondary metabolites are produced by bacterial symbionts. The review finishes by discussing the directions for future development and production of clinically relevant amounts of these natural products and their analogues through aquaculture, chemical synthesis, and biosynthesis by bacterial symbionts.

RevDate: 2019-06-14

Jiang J, Y Lu (2019)

Metabolite profiling of Breviolum minutum in response to acidification.

Aquatic toxicology (Amsterdam, Netherlands), 213:105215 pii:S0166-445X(19)30270-X [Epub ahead of print].

Coral reefs are in significant decline globally due to climate change and environmental pollution. The ocean is becoming more acidic due to rising atmospheric pCO2, and ocean acidification is considered a major threat to coral reefs. However, little is known about the exact mechanism by which acidification impacts coral symbiosis. As an important component of the symbiotic association, to explore the responses of symbionts could greatly enhance our understanding of this issue. The present work aimed to identify metabolomic changes of Breviolum minutum in acidification (low pH) condition, and investigate the underlying mechanisms responsible. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was applied to determine metabolite profiles after exposure to ambient and acidic conditions. We analysed the resulting metabolite data, and acidification appeared to have little effect on photosynthetic parameters, but it inhibited growth. Marked alterations in metabolite pools were observed in response to acidification that may be important in acclimation to climate change. Acidification may affect the biosynthesis of amino acids and proteins, and thereby inhibit the growth of B. minutum. Metabolites identified using this approach provide targets for future analyses aimed at understanding the responses of Symbiodiniaceae to environmental disturbance.

RevDate: 2019-06-14

Rader B, McAnulty SJ, SV Nyholm (2019)

Persistent symbiont colonization leads to a maturation of hemocyte response in the Euprymna scolopes/Vibrio fischeri symbiosis.

MicrobiologyOpen [Epub ahead of print].

The binary association between the squid, Euprymna scolopes, and its symbiont, Vibrio fischeri, serves as a model system to study interactions between beneficial bacteria and the innate immune system. Previous research demonstrated that binding of the squid's immune cells, hemocytes, to V. fischeri is altered if the symbiont is removed from the light organ, suggesting that host colonization alters hemocyte recognition of V. fischeri. To investigate the influence of symbiosis on immune maturation during development, we characterized hemocyte binding and phagocytosis of V. fischeri and nonsymbiotic Vibrio harveyi from symbiotic (sym) and aposymbiotic (apo) juveniles, and wild-caught and laboratory-raised sym and apo adults. Our results demonstrate that while light organ colonization by V. fischeri did not alter juvenile hemocyte response, these cells bound a similar number of V. fischeri and V. harveyi yet phagocytosed only V. harveyi. Our results also indicate that long-term colonization altered the adult hemocyte response to V. fischeri but not V. harveyi. All hemocytes from adult squid, regardless of apo or sym state, both bound and phagocytosed a similar number of V. harveyi while hemocytes from both wild-caught and sym-raised adults bound significantly fewer V. fischeri, although more V. fischeri were phagocytosed by hemocytes from wild-caught animals. In contrast, hemocytes from apo-raised squid bound similar numbers of both V. fischeri and V. harveyi, although more V. harveyi cells were engulfed, suggesting that blood cells from apo-raised adults behaved similarly to juvenile hosts. Taken together, these data suggest that persistent colonization by the light organ symbiont is required for hemocytes to differentially bind and phagocytose V. fischeri. The cellular immune system of E. scolopes likely possesses multiple mechanisms at different developmental stages to promote a specific and life-long interaction with the symbiont.

RevDate: 2019-06-14

Martínez-Medina A, Pescador-Azofra L, Terrón-Camero L, et al (2019)

Nitric oxide shape plant-fungi interactions.

Journal of experimental botany pii:5518916 [Epub ahead of print].

In their complex environments, plants continuously interact with fungi. While many of those interactions are detrimental for plants and challenge plant capability for growth and survival, others are beneficial improving plant growth and stress tolerance. Accordingly, plants have evolved sophisticated mechanisms to restrict pathogenic interactions while promoting mutualistic relationships. Several studies demonstrated the importance of nitric oxide (NO) in the regulation of plant defence mounted against fungal pathogens. NO triggers a reprograming of defence related gene expression, the production of secondary metabolites with antimicrobial properties and the hypersensitive response. More recent evidences have further shown the regulation of NO during the establishment of plant-fungus mutualistic associations from early steps of the interaction. Indeed NO has been recently shown to be produced by the plant after the recognition of root fungal symbionts, and to be required for the optimal control of the mycorrhizal symbiosis. Although studies dealing with NO function in plant-fungus mutualistic associations are still scarce, experimental data support a different regulation patterns and functions for NO in plant interactions with pathogenic and mutualistic fungi. Here we review recent evidences about NO function in plant-fungus interactions, trying to identify common and differential patterns related to the fungus life-style and their impact on plant health.

RevDate: 2019-06-14

Lipa P, Vinardell JM, M Janczarek (2019)

Transcriptomic Studies Reveal that the Rhizobium leguminosarum Serine/Threonine Protein Phosphatase PssZ has a Role in the Synthesis of Cell-Surface Components, Nutrient Utilization, and Other Cellular Processes.

International journal of molecular sciences, 20(12): pii:ijms20122905.

Rhizobium leguminosarum bv. trifolii is a soil bacterium capable of establishing symbiotic associations with clover plants (Trifolium spp.). Surface polysaccharides, transport systems, and extracellular components synthesized by this bacterium are required for both the adaptation to changing environmental conditions and successful infection of host plant roots. The pssZ gene located in the Pss-I region, which is involved in the synthesis of extracellular polysaccharide, encodes a protein belonging to the group of serine/threonine protein phosphatases. In this study, a comparative transcriptomic analysis of R. leguminosarum bv. trifolii wild-type strain Rt24.2 and its derivative Rt297 carrying a pssZ mutation was performed. RNA-Seq data identified a large number of genes differentially expressed in these two backgrounds. Transcriptome profiling of the pssZ mutant revealed a role of the PssZ protein in several cellular processes, including cell signalling, transcription regulation, synthesis of cell-surface polysaccharides and components, and bacterial metabolism. In addition, we show that inactivation of pssZ affects the rhizobial ability to grow in the presence of different sugars and at various temperatures, as well as the production of different surface polysaccharides. In conclusion, our results identified a set of genes whose expression was affected by PssZ and confirmed the important role of this protein in the rhizobial regulatory network.

RevDate: 2019-06-14

Zan J, Li Z, Tianero MD, et al (2019)

A microbial factory for defensive kahalalides in a tripartite marine symbiosis.

Science (New York, N.Y.), 364(6445):.

Chemical defense against predators is widespread in natural ecosystems. Occasionally, taxonomically distant organisms share the same defense chemical. Here, we describe an unusual tripartite marine symbiosis, in which an intracellular bacterial symbiont ("Candidatus Endobryopsis kahalalidefaciens") uses a diverse array of biosynthetic enzymes to convert simple substrates into a library of complex molecules (the kahalalides) for chemical defense of the host, the alga Bryopsis sp., against predation. The kahalalides are subsequently hijacked by a third partner, the herbivorous mollusk Elysia rufescens, and employed similarly for defense. "Ca E. kahalalidefaciens" has lost many essential traits for free living and acts as a factory for kahalalide production. This interaction between a bacterium, an alga, and an animal highlights the importance of chemical defense in the evolution of complex symbioses.

RevDate: 2019-06-14

Dreyer J, Rautenbach M, Booysen E, et al (2019)

Xenorhabdus khoisanae SB10 produces Lys-rich PAX lipopeptides and a Xenocoumacin in its antimicrobial complex.

BMC microbiology, 19(1):132 pii:10.1186/s12866-019-1503-x.

BACKGROUND: Xenorhabdus spp. live in close symbiosis with nematodes of the Steinernema genus. Steinernema nematodes infect an insect larva and release their symbionts into the haemocoel of the insect. Once released into the haemocoel, the bacteria produce bioactive compounds to create a semi-exclusive environment by inhibiting the growth of bacteria, yeasts and molds. The antimicrobial compounds thus far identified are xenocoumacins, xenortides, xenorhabdins, indole derivatives, xenoamicins, bicornutin and a number of antimicrobial peptides. The latter may be linear peptides such as the bacteriocins xenocin and xenorhabdicin, rhabdopeptides and cabanillasin, or cyclic, such as PAX lipopeptides, taxlllaids, xenobactin and szentiamide. Thus far, production of antimicrobial compounds have been reported for Xenorhabdus nematophila, Xenorhabdus budapestensis, Xenorhabdus cabanillasii, Xenorhabdus kozodoii, Xenorhabdus szentirmaii, Xenorhabdus doucetiae, Xenorhabdus mauleonii, Xenorhabdus indica and Xenorhabdus bovienii. Here we describe, for the first time, PAX lipopeptides and xenocoumacin 2 produced by Xenorhabdus khoisanae. These compounds were identified using ultraperformance liquid chromatography, linked to high resolution electrospray ionisation mass spectrometry and tandem mass spectrometry.

RESULTS: Cell-free supernatants of X. khoisanae SB10 were heat stable and active against Bacillus subtilis subsp. subtilis, Escherichia coli and Candida albicans. Five lysine-rich lipopeptides from the PAX group were identified in HPLC fractions, with PAX1' and PAX7 present in the highest concentrations. Three novel PAX7 peptides with putative enoyl modifications and two linear analogues of PAX1' were also detected. A small antibiotic compound, yellow in colour and λmax of 314 nm, was recovered from the HPLC fractions and identified as xenocoumacin 2. The PAX lipopeptides and xenocoumacin 2 correlated with the genes and gene clusters in the genome of X. khoisanae SB10.

CONCLUSION: With UPLC-MS and MSe analyses of compounds in the antimicrobial complex of X. khoisanae SB10, a number of PAX peptides and a xenocoumacin were identified. The combination of pure PAX1' peptide with xenocoumacin 2 resulted in high antimicrobial activity. Many of the fractions did, however, contain labile compounds and some fractions were difficult to resolve. It is thus possible that strain SB10 may produce more antimicrobial compounds than reported here, as suggested by the APE Ec biosynthetic complex. Further research is required to develop these broad-spectrum antimicrobial compounds into drugs that may be used in the fight against microbial infections.

RevDate: 2019-06-14

Ikram M, Ali N, Jan G, et al (2019)

Endophytic fungal diversity and their interaction with plants for agriculture sustainability under stressful condition.

Recent patents on food, nutrition & agriculture pii:FNA-EPUB-98764 [Epub ahead of print].

Endophytic fungi or endophytes as fascinating group of organism that colonize widely the healthy internal tissues of living plants, and do not cause any symptoms of disease in the host cells. Several decades of study and research have rustled the co-existing endophytes with their host plants, which can significantly influence the formation of metabolic products in plants, its ability to produce new interesting bioactive compound, which are of pharmaceutical, industrial and agricultural importance. The analytical results indicate that the endophytic fungi can confer profound impacts on plant communities by enhancing their growth, increasing their fitness, strengthening their tolerances to abiotic and biotic stresses, enhance defense mechanism and promoting their accumulation of secondary metabolites that provide immunity to the victims. This review focused on the biodiversity and biological roles of endophytic fungi in association with their host plants through reviewing of published research data obtained from the last 30 years.

RevDate: 2019-06-13

Lee J, Kim CH, Jang HA, et al (2019)

Burkholderia gut symbiont modulates titer of specific juvenile hormone in the bean bug Riptortus pedestris.

Developmental and comparative immunology pii:S0145-305X(19)30219-8 [Epub ahead of print].

Recent studies have provided molecular evidence that gut symbiotic bacteria modulate host insect development, fitness and reproduction. However, the molecular mechanisms through which gut symbionts regulate these aspects of host physiology remain elusive. To address these questions, we prepared two different Riptortus-Burkholderia insect models, Burkholderia gut symbiont-colonized (Sym) Riptortus pedestris insects and gut symbiont-noncolonized (Apo) insects. Upon LC-MS analyses, juvenile hormone III skipped bisepoxide (JHSB3) was newly identified from Riptortus Apo- and Sym-female and male adults' insect hemolymph and JHSB3 titer in the Apo- and Sym-female insects were measured because JH is important for regulating reproduction in adult insects. The JHSB3 titer in the Sym-females were consistently higher compared to those of Apo-females. Since previous studies reported that Riptortus hexamerin-α and vitellogenin proteins were upregulated by the topical abdominal application of a JH-analog, chemically synthesized JHSB3 was administered to Apo-females. As expected, the hexamerin-α and vitellogenin proteins were dramatically increased in the hemolymph of JHSB3-treated Apo-females, resulting in increased egg production compared to that in Sym-females. Taken together, these results demonstrate that colonization of Burkholderia gut symbiont in the host insect stimulates biosynthesis of the heteroptera-specific JHSB3, leading to larger number of eggs produced and enhanced fitness in Riptortus host insects.

RevDate: 2019-06-13

Jung M, DH Lee (2019)

Abundance and diversity of gut-symbiotic bacteria, the genus Burkholderia in overwintering Riptortus pedestris (Hemiptera: Alydidae) populations and soil in South Korea.

PloS one, 14(6):e0218240 pii:PONE-D-19-05141.

Riptortus pedestris is a major agricultural pest on leguminous plants in South Korea and Japan. Recent studies have revealed that R. pedestris can form beneficial symbiosis with bacteria belonging to genus Burkholderia acquired from soil newly for every generation. Although their physiological interactions are relatively well-understood, infection rate and abundance of the Burkholderia in overwintering natural populations of R. pedestris remain unknown. Therefore, the objective of this study was to characterize Burkholderia infection ratio and clade composition of overwintering R. pedestris populations as well as prevalence and diversity of the genus Burkholderia in soil by conducting a two-year field survey. From the field survey, we found 29 overwintering R. pedestris adults in forested areas nearby soybean fields. Diagnostic PCR analysis revealed that overall infection rate of the symbiotic Burkholderia was 93.1% from overwintering adults. Among the Burkholderia-infected R. pedestris, 70.4% of individuals harbored unclassified Burkholderia clades whereas 22.2% and 7.4% of R. pedestris harbor stinkbug-associated beneficial and environmental (SBE) group and Burkholderia cepacia and complex (BCC), respectively. All R. pedestris were infected with a single clade of Burkholderia. In soil, 56.2% of soil samples were Burkholderia positive, and unlike R. pedestris, multiple Burkholderia clades were detected from 62.2% of those samples. Clade composition of the genus Burkholderia in the samples with the bacteria was 91.1%, 60.0%, 31.1% and 8.8% for plant-associated beneficial and environment (PBE), BCC, SBE and unclassified clade, respectively.

RevDate: 2019-06-13

Liu Z, Chen W, Jiao S, et al (2019)

New insight into the evolution of symbiotic genes in black locust-associated rhizobia.

Genome biology and evolution pii:5514480 [Epub ahead of print].

Nitrogen fixation in legumes occurs via symbiosis with rhizobia. This process involves packages of symbiotic genes on mobile genetic elements that are readily transferred within or between rhizobial species, furnishing the recipient with the ability to interact with plant hosts. However, it remains elusive whether plant host migration has played a role in shaping the current distribution of genetic variation in symbiotic genes. Herein, we examined the genetic structure and phylogeographic pattern of symbiotic genes in 286 symbiotic strains of Mesorhizobium nodulating black locust (Robinia pseudoacacia), a cross-continental invasive legume species that is native to North America. We conducted detailed phylogeographic analysis and approximate Bayesian computation to unravel the complex demographic history of five key symbiotic genes. The sequencing results indicate an origin of symbiotic genes in Germany rather than North America. Our findings provide strong evidence of prehistoric lineage splitting and spatial expansion events resulting in multiple radiations of descendent clones from founding sequence types worldwide. Estimates of the timescale of divergence in North American and Chinese subclades suggest that black locust-specific symbiotic genes have been present in these continent many thousands of years before recent migration of plant host. Although numerous crop plants, including legumes, have found their centers of origin as centers of evolution and diversity, the number of legume-specific symbiotic genes with a known geographic origin is limited. This work sheds light on the coevolution of legumes and rhizobia.

RevDate: 2019-06-13

Defrenne CE, Philpott TJ, Guichon SHA, et al (2019)

Shifts in Ectomycorrhizal Fungal Communities and Exploration Types Relate to the Environment and Fine-Root Traits Across Interior Douglas-Fir Forests of Western Canada.

Frontiers in plant science, 10:643.

Large-scale studies that examine the responses of ectomycorrhizal fungi across biogeographic gradients are necessary to assess their role in mediating current and predicted future alterations in forest ecosystem processes. We assessed the extent of environmental filtering on interior Douglas-fir (Pseudotsuga menziesii var. glauca (Beissn.) Franco) ectomycorrhizal fungal communities across regional gradients in precipitation, temperature, and soil fertility in interior Douglas-fir dominated forests of western Canada. We also examined relationships between fine-root traits and mycorrhizal fungal exploration types by combining root and fungal trait measurements with next-generation sequencing. Temperature, precipitation, and soil C:N ratio affected fungal community dissimilarity and exploration type abundance but had no effect on α-diversity. Fungi with rhizomorphs (e.g., Piloderma sp.) or proteolytic abilities (e.g., Cortinarius sp.) dominated communities in warmer and less fertile environments. Ascomycetes (e.g., Cenococcum geophilum) or shorter distance explorers, which potentially cost the plant less C, were favored in colder/drier climates where soils were richer in total nitrogen. Environmental filtering of ectomycorrhizal fungal communities is potentially related to co-evolutionary history between Douglas-fir populations and fungal symbionts, suggesting success of interior Douglas-fir as climate changes may be dependent on maintaining strong associations with local communities of mycorrhizal fungi. No evidence for a link between root and fungal resource foraging strategies was found at the regional scale. This lack of evidence further supports the need for a mycorrhizal symbiosis framework that is independent of root trait frameworks, to aid in understanding belowground plant uptake strategies across environments.

RevDate: 2019-06-13

Habineza P, Muhammad A, Ji T, et al (2019)

The Promoting Effect of Gut Microbiota on Growth and Development of Red Palm Weevil, Rhynchophorus ferrugineus (Olivier) (Coleoptera: Dryophthoridae) by Modulating Its Nutritional Metabolism.

Frontiers in microbiology, 10:1212.

Red palm weevil (RPW), Rhynchophorus ferrugineus Olivier, is a destructive pest for palm trees worldwide. Recent studies have shown that RPW gut is colonized by microbes and alterations in gut microbiota can significantly modify its hemolymph nutrition content. However, the exact effects of gut microbiota on RPW phenotype and the underlying mechanisms remain elusive. Here germ-free (GF) RPW larvae were generated from dechorionated eggs which were reared on sterilized artificial food under axenic conditions. Compared with controls, the larval development of GF RPW individuals was markedly depressed and their body mass was reduced as well. Furthermore, the content of hemolymph protein, glucose and triglyceride were dropped significantly in GF RPW larvae. Interestingly, introducing gut microbiota into GF individuals could significantly increase the levels of the three nutrition indices. Additionally, it has also been demonstrated that RPW larvae monoassociated with Lactococcus lactis exhibited the same level of protein content with the CR (conventionally reared) insects while feeding Enterobacter cloacae to GF larvae increased their hemolymph triglyceride and glucose content markedly. Consequently, our findings suggest that gut microbiota profoundly affect the development of this pest by regulating its nutrition metabolism and different gut bacterial species show distinct impact on host physiology. Taken together, the establishment of GF and gnotobiotic RPW larvae will advance the elucidation of molecular mechanisms behind the interactions between RPW and its gut microbiota.

RevDate: 2019-06-13

Lee SJ, Morse D, M Hijri (2019)

Holobiont chronobiology: mycorrhiza may be a key to linking aboveground and underground rhythms.

Mycorrhiza pii:10.1007/s00572-019-00903-4 [Epub ahead of print].

Circadian clocks are nearly ubiquitous timing mechanisms that can orchestrate rhythmic behavior and gene expression in a wide range of organisms. Clock mechanisms are becoming well understood in fungal, animal, and plant model systems, yet many of these organisms are surrounded by a complex and diverse microbiota which should be taken into account when examining their biology. Of particular interest are the symbiotic relationships between organisms that have coevolved over time, forming a unit called a holobiont. Several studies have now shown linkages between the circadian rhythms of symbiotic partners. Interrelated regulation of holobiont circadian rhythms seems thus important to coordinate shifts in activity over the day for all the partners. Therefore, we suggest that the classical view of "chronobiological individuals" should include "a holobiont" rather than an organism. Unfortunately, mechanisms that may regulate interspecies temporal acclimation and the evolution of the circadian clock in holobionts are far from being understood. For the plant holobiont, our understanding is particularly limited. In this case, the holobiont encompasses two different ecosystems, one above and the other below the ground, with the two potentially receiving timing information from different synchronizing signals (Zeitgebers). The arbuscular mycorrhizal (AM) symbiosis, formed by plant roots and fungi, is one of the oldest and most widespread associations between organisms. By mediating the nutritional flux between the plant and the many microbes in the soil, AM symbiosis constitutes the backbone of the plant holobiont. Even though the importance of the AM symbiosis has been well recognized in agricultural and environmental sciences, its circadian chronobiology remains almost completely unknown. We have begun to study the circadian clock of arbuscular mycorrhizal fungi, and we compile and here discuss the available information on the subject. We propose that analyzing the interrelated temporal organization of the AM symbiosis and determining its underlying mechanisms will advance our understanding of the role and coordination of circadian clocks in holobionts in general.

RevDate: 2019-06-13
CmpDate: 2019-06-10

Sabūnas V, Radzijevskaja J, Sakalauskas P, et al (2019)

Dirofilaria repens in dogs and humans in Lithuania.

Parasites & vectors, 12(1):177 pii:10.1186/s13071-019-3406-y.

BACKGROUND: In Lithuania, the first case of canine subcutaneous dirofilariosis was recorded in 2010. Since then, an increasing number of cases of canine dirofilariosis have been documented in different veterinary clinics throughout the country. Human dirofilariosis was diagnosed in Lithuania for the first time in September 2011. However, to the authors' knowledge, there are no published data on the presence and prevalence of autochthonous dirofilariosis in dogs and humans in the country. The present study provides information about the predominant species and prevalence of Dirofilaria in dogs and describes the cases of human dirofilariosis in Lithuania. It also outlines PCR detection of the bacterial endosymbiont Wolbachia that contributes to the inflammatory features of filarioid infection.

RESULTS: A total of 2280 blood samples and six adult worms from pet and shelter dogs were collected in the central and eastern regions of Lithuania in 2013-2015. Based on their morphological appearance, morphometric measurements and molecular analysis, all the adult nematodes were identified as Dirofilaria repens. The diagnosis of microfilariae in blood samples was based on blood smear analysis and Knott's test. The PCR and sequence analysis of the ribosomal DNA ITS2 region and cox1 gene confirmed the presence of D. repens. Overall, 61 (2.7%) of the 2280 blood samples were found to be positive for the presence of D. repens. The infection rate of D. repens was significantly higher in shelter dogs (19.0%; 19/100) than in pet dogs (1.9%; 42/2180) (χ2 = 100.039, df = 1, P < 0.0001). Forty-nine DNA samples of D. repens-infected dogs were tested for the presence of the bacterial endosymbiont Wolbachia and, of these, 40 samples (81.6%) were found to be positive. Three ocular and six subcutaneous cases of human dirofilariosis were diagnosed in Lithuania in the period 2011-2018.

CONCLUSIONS: To the authors' knowledge, this is the first report of autochthonous D. repens infection in dogs and humans in Lithuania. The present data demonstrate that D. repens is the main etiological agent of dirofilariosis in Lithuania. The DNA of the filarioid endosymbiotic bacterium Wolbachia was detected in the vast majority of dogs infected with D. repens.

RevDate: 2019-06-13
CmpDate: 2019-06-11

Du J, Jiang S, Wei J, et al (2019)

[Co-expression of lignocellulase from termite and their endosymbionts].

Sheng wu gong cheng xue bao = Chinese journal of biotechnology, 35(2):244-253.

Natural lignocellulosic materials contain cellulose, hemicellulose, and lignin. Cellulose hydrolysis to glucose requires a series of lignocellulases. Recently, the research on the synergistic effect of lignocellulases has become a new research focus. Here, four lignocellulase genes encoding β-glucosidase, endo-1,4-β-glucanase, xylanase and laccase from termite and their endosymbionts were cloned into pETDuet-1 and pRSFDuet-1 and expressed in Escherichia coli. After SDS-PAGE analysis, the corresponding protein bands consistent with the theoretical values were observed and all the proteins showed enzyme activities. We used phosphoric acid swollen cellulose (PASC) as substrate to measure the synergistic effect of crude extracts of co-expressing enzymes and the mixture of single enzyme. The co-expressed enzymes increased the degradation efficiency of PASC by 44% compared with the single enzyme mixture; while the degradation rate increased by 34% and 20%, respectively when using filter paper and corn cob pretreated with phosphoric acid as substrates. The degradation efficiency of the co-expressed enzymes was higher than the total efficiency of the single enzyme mixture.

RevDate: 2019-06-13
CmpDate: 2019-06-11

Shaikevich E, Bogacheva A, Rakova V, et al (2019)

Wolbachia symbionts in mosquitoes: Intra- and intersupergroup recombinations, horizontal transmission and evolution.

Molecular phylogenetics and evolution, 134:24-34.

Many mosquitoes harbour Wolbachia symbionts that could affect the biology of their host in different ways. Evolutionary relationships of mosquitoes' Wolbachia infection, geographical distribution and symbiont prevalence in many mosquito species are not yet clear. Here, we present the results of Wolbachia screening of 17 mosquito species of four genera-Aedes, Anopheles, Coquillettidia and Culex collected from five regions of Eastern Europe and the Caucasus in 2012-2016. Based on multilocus sequence typing (MLST) data previously published and generated in this study, we try to reveal genetic links between mosquitoes' and other hosts' Wolbachia. The Wolbachia symbionts are found in Culex pipiens, Aedes albopictus and Coquillettidia richiardii and for the first time in Aedes cinereus and Aedes cantans, which are important vectors of human pathogens. Phylogenetic analysis demonstrated multiple origins of infection in mosquitoes although the one-allele-criterion approach revealed links among B-supergroup mosquito Wolbachia with allele content of lepidopteran hosts. The MLST gene content of strain wAlbA from the A-supergroup is linked with different ant species. Several cases of intersupergroup recombinations were found. One of them occurred in the wAlbaB strain of Aedes albopictus, which contains the coxA allele of the A-supergroup, whereas other loci, including wsp, belong to supergroup B. Other cases are revealed for non-mosquito symbionts and they exemplified genetic exchanges of A, B and F supergroups. We conclude that modern Wolbachia diversity in mosquitoes and in many other insect taxa is a recent product of strain recombination and symbiont transfers.

RevDate: 2019-06-14
CmpDate: 2019-06-14

Kitamoto M, Tokuda G, Watanabe H, et al (2019)

Characterization of CBM36-containing GH11 endoxylanase NtSymX11 from the hindgut metagenome of higher termite Nasutitermes takasagoensis displaying prominent catalytic activity.

Carbohydrate research, 474:1-7.

Symbionts in the gut of termites are expected to be large sources of enzymes involved in lignocellulose degradation, but their biotechnological potential has not been fully explored. In this study, we expressed, purified, and biochemically characterized a glycoside hydrolase family 11 xylanase, NtSymX11, from a symbiotic bacterium of the higher termite, Nasutitermes takasagoensis. NtSymX11 is a multimodular enzyme consisting of a catalytic domain and two tandem carbohydrate-binding modules (CBM36). The pH and temperature optima of NtSymX11 were pH 6.0 and 40 °C, respectively. By comparing the properties of full-length and truncated variants of NtSymX11, it was shown that CBM36 decreases the enzyme stability at acidic pH and high temperature. The main products from xylohexaose and various xylan substrates were X1-X3 xylooligosaccharides. Analysis of kinetic parameters indicated that NtSymX11 displays an outstanding catalytic performance when compared to other reported xylanases, and CBM36 enhances the activity by increasing the affinity to the substrate. Addition of Ca2+ boosted the activity of full-length enzyme, but not the truncated variant lacking the CBM, against the insoluble substrate, suggesting that CBM36 plays a role in the Ca2+-dependent increase of catalytic efficiency.

RevDate: 2019-06-14
CmpDate: 2019-06-14

Jankauskaitė L, Misevičienė V, Vaidelienė L, et al (2018)

Lower Airway Virology in Health and Disease-From Invaders to Symbionts.

Medicina (Kaunas, Lithuania), 54(5):.

Studies of human airway virome are relatively recent and still very limited. Culture-independent microbial techniques showed growing evidence of numerous viral communities in the respiratory microbial ecosystem. The significance of different acute respiratory viruses is already known in the pathogenesis of chronic conditions, such as asthma, cystic fibrosis (CF), or chronic obstructive lung disease (COPD), and their exacerbations. Viral pathogens, such as influenza, metapneumovirus, parainfluenza, respiratory syncytial virus, or rhinovirus, have been associated with impaired immune response, acute exacerbations, and decrease in lung function in chronic lung diseases. However, more data have attributed a role to Herpes family viruses or the newly identified Anelloviridae family of viruses in chronic diseases, such as asthma, idiopathic pulmonary fibrosis (IPF), or CF. Impaired antiviral immunity, bacterial colonization, or used medication, such as glucocorticoids or antibiotics, contribute to the imbalance of airway microbiome and may shape the local viral ecosystem. A specific part of virome, bacteriophages, frames lung microbial communities through direct contact with its host, the specific bacteria known as Pseudomonas aeruginosa or their biofilm formation. Moreover, antibiotic resistance is induced through phages via horizontal transfer and leads to more severe exacerbations of chronic airway conditions. Morbidity and mortality of asthma, COPD, CF, and IPF remains high, despite an increased understanding and knowledge about the impact of respiratory virome in the pathogenesis of these conditions. Thus, more studies focus on new prophylactic methods or therapeutic agents directed toward viral⁻host interaction, microbial metabolic function, or lung microbial composition rearrangement.

RevDate: 2019-06-13
CmpDate: 2019-06-13

Li J, Han M, J Yu (2018)

Simple paratransgenic mosquitoes models and their dynamics.

Mathematical biosciences, 306:20-31.

To study the interactive dynamics of wild mosquitoes and mosquitoes carrying genetically-modified bacteria, we formulate continuous-time homogeneous and stage-structured models in this study. With appropriate transformations, complete results of the existence and stability of all boundary and positive equilibria for the homogeneous model are established and complete results of the existence and local stability of all boundary and positive equilibria for the stage-structured model are obtained as well. The outcomes from the homogeneous and the stage-structured models are similar. Based on the homogeneous model, we particularly investigate how the horizontal transmission of the transgenic bacteria, via the uptake rate of the transgenic bacteria, affects the interactive dynamics.

RevDate: 2019-06-13
CmpDate: 2019-06-12

Macpherson AJ, SC Ganal-Vonarburg (2018)

IgA-about the unexpected.

The Journal of experimental medicine, 215(8):1965-1966.

In this issue of JEM, Nakajima et al. (https://doi.org/10.1084/jem.20180427) demonstrate that glycan-dependent, epitope-independent IgA coating of intestinal bacteria alters bacterial gene expression and metabolism. This conferred coated bacteria with fitness within the mucus niche and contributed to intestinal homeostasis through cross-phylum interactions.

RevDate: 2019-06-13
CmpDate: 2019-06-10

Boldock E, Surewaard BGJ, Shamarina D, et al (2018)

Human skin commensals augment Staphylococcus aureus pathogenesis.

Nature microbiology, 3(8):881-890.

All bacterial infections occur within a polymicrobial environment, from which a pathogen population emerges to establish disease within a host. Emphasis has been placed on prevention of pathogen dominance by competing microflora acting as probiotics1. Here we show that the virulence of the human pathogen Staphylococcus aureus is augmented by native, polymicrobial, commensal skin flora and individual species acting as 'proinfectious agents'. The outcome is pathogen proliferation, but not commensal. Pathogenesis augmentation can be mediated by particulate cell wall peptidoglycan, reducing the S. aureus infectious dose by over 1,000-fold. This phenomenon occurs using a range of S. aureus strains and infection models and is not mediated by established receptor-mediated pathways including Nod1, Nod2, Myd88 and the NLPR3 inflammasome. During mouse sepsis, augmentation depends on liver-resident macrophages (Kupffer cells) that capture and internalize both the pathogen and the proinfectious agent, leading to reduced production of reactive oxygen species, pathogen survival and subsequent multiple liver abscess formation. The augmented infection model more closely resembles the natural situation and establishes the role of resident environmental microflora in the initiation of disease by an invading pathogen. As the human microflora is ubiquitous2, its role in increasing susceptibility to infection by S. aureus highlights potential strategies for disease prevention.

RevDate: 2019-06-13
CmpDate: 2019-06-13

Fourie R, Kuloyo OO, Mochochoko BM, et al (2018)

Iron at the Centre of Candida albicans Interactions.

Frontiers in cellular and infection microbiology, 8:185.

Iron is an absolute requirement for both the host and most pathogens alike and is needed for normal cellular growth. The acquisition of iron by biological systems is regulated to circumvent toxicity of iron overload, as well as the growth deficits imposed by iron deficiency. In addition, hosts, such as humans, need to limit the availability of iron to pathogens. However, opportunistic pathogens such as Candida albicans are able to adapt to extremes of iron availability, such as the iron replete environment of the gastrointestinal tract and iron deficiency during systemic infection. C. albicans has developed a complex and effective regulatory circuit for iron acquisition and storage to circumvent iron limitation within the human host. As C. albicans can form complex interactions with both commensal and pathogenic co-inhabitants, it can be speculated that iron may play an important role in these interactions. In this review, we highlight host iron regulation as well as regulation of iron homeostasis in C. albicans. In addition, the review argues for the need for further research into the role of iron in polymicrobial interactions. Lastly, the role of iron in treatment of C. albicans infection is discussed.

RevDate: 2019-06-13
CmpDate: 2019-06-10

Stouthamer CM, Kelly S, MS Hunter (2018)

Enrichment of low-density symbiont DNA from minute insects.

Journal of microbiological methods, 151:16-19.

Symbioses between bacteria and insects are often associated with changes in important biological traits that can significantly affect host fitness. To a large extent, studies of these interactions have been based on physiological changes or induced phenotypes in the host, and the genetic mechanisms by which symbionts interact with their hosts have only recently become better understood. Learning about symbionts has been challenging in part due to difficulties such as obtaining enough high quality genomic material for high throughput sequencing technology, especially for symbionts present in low titers, and in small or difficult to rear non-model hosts. Here we introduce a new method that substantially increases the yield of bacterial DNA in minute arthropod hosts, and requires less starting material relative to previous published methods.

RevDate: 2019-06-13
CmpDate: 2019-06-10

Toju H, Peay KG, Yamamichi M, et al (2018)

Core microbiomes for sustainable agroecosystems.

Nature plants, 4(5):247-257.

In an era of ecosystem degradation and climate change, maximizing microbial functions in agroecosystems has become a prerequisite for the future of global agriculture. However, managing species-rich communities of plant-associated microbiomes remains a major challenge. Here, we propose interdisciplinary research strategies to optimize microbiome functions in agroecosystems. Informatics now allows us to identify members and characteristics of 'core microbiomes', which may be deployed to organize otherwise uncontrollable dynamics of resident microbiomes. Integration of microfluidics, robotics and machine learning provides novel ways to capitalize on core microbiomes for increasing resource-efficiency and stress-resistance of agroecosystems.

RevDate: 2019-06-13
CmpDate: 2019-06-10

Chan CX, Vaysberg P, Price DC, et al (2018)

Active Host Response to Algal Symbionts in the Sea Slug Elysia chlorotica.

Molecular biology and evolution, 35(7):1706-1711.

Sacoglossan sea slugs offer fascinating systems to study the onset and persistence of algal-plastid symbioses. Elysia chlorotica is particularly noteworthy because it can survive for months, relying solely on energy produced by ingested plastids of the stramenopile alga Vaucheria litorea that are sequestered in cells lining its digestive diverticula. How this animal can maintain the actively photosynthesizing organelles without replenishment of proteins from the lost algal nucleus remains unknown. Here, we used RNA-Seq analysis to test the idea that plastid sequestration leaves a significant signature on host gene expression during E. chlorotica development. Our results support this hypothesis and show that upon exposure to and ingestion of V. litorea plastids, genes involved in microbe-associated molecular patterns and oxidative stress-response mechanisms are significantly up-regulated. Interestingly, our results with E. chlorotica mirror those found with corals that maintain dinoflagellates as intact cells in symbiosomes, suggesting parallels between these animal-algal symbiotic interactions.

RevDate: 2019-06-13
CmpDate: 2019-06-10

Vdacný P (2018)

Evolutionary Associations of Endosymbiotic Ciliates Shed Light on the Timing of the Marsupial-Placental Split.

Molecular biology and evolution, 35(7):1757-1769.

Trichostome ciliates are among the most conspicuous protists in the gastrointestinal tract of a large variety of vertebrates. However, little is still known about phylogeny of the trichostome/vertebrate symbiotic systems, evolutionary correlations between trichostome extrinsic traits, and character-dependent diversification of trichostomes. These issues were investigated here, using the relaxed molecular clock technique along with stochastic mapping of character evolution, and binary-state speciation and extinction models. Clock analyses revealed that trichostomes colonized the vertebrate gastrointestinal tract ∼135 Ma, that is, near the paleontological minimum for the split of therian mammals into marsupials and placentals. According to stochastic mapping, the last common ancestor of trichostomes most likely invaded the hindgut of a mammal. Although multiple shifts to fish/amphibian or avian hosts and to the foregut compartments took place during the trichostome phylogeny, only transition to the foregut was recognized as a key innovation responsible for the explosive radiation of ophryoscolecid trichostomes after the Cretaceous/Tertiary boundary, when ungulates began their diversification. Since crown radiations of main trichostome lineages follow those of their mammalian hosts and are in agreement with their historic dispersal routes, the present time-calibrated phylogeny might help to elucidate controversies in the geological and molecular timing of the split between marsupials and placental mammals.

RevDate: 2019-06-13
CmpDate: 2019-06-10

Leth ML, Ejby M, Workman C, et al (2018)

Differential bacterial capture and transport preferences facilitate co-growth on dietary xylan in the human gut.

Nature microbiology, 3(5):570-580.

Metabolism of dietary glycans is pivotal in shaping the human gut microbiota. However, the mechanisms that promote competition for glycans among gut commensals remain unclear. Roseburia intestinalis, an abundant butyrate-producing Firmicute, is a key degrader of the major dietary fibre xylan. Despite the association of this taxon to a healthy microbiota, insight is lacking into its glycan utilization machinery. Here, we investigate the apparatus that confers R. intestinalis growth on different xylans. R. intestinalis displays a large cell-attached modular xylanase that promotes multivalent and dynamic association to xylan via four xylan-binding modules. This xylanase operates in concert with an ATP-binding cassette transporter to mediate breakdown and selective internalization of xylan fragments. The transport protein of R. intestinalis prefers oligomers of 4-5 xylosyl units, whereas the counterpart from a model xylan-degrading Bacteroides commensal targets larger ligands. Although R. intestinalis and the Bacteroides competitor co-grew in a mixed culture on xylan, R. intestinalis dominated on the preferred transport substrate xylotetraose. These findings highlight the differentiation of capture and transport preferences as a possible strategy to facilitate co-growth on abundant dietary fibres and may offer a unique route to manipulate the microbiota based on glycan transport preferences in therapeutic interventions to boost distinct taxa.

RevDate: 2019-06-14
CmpDate: 2019-06-14

Craft KM, SD Townsend (2018)

The Human Milk Glycome as a Defense Against Infectious Diseases: Rationale, Challenges, and Opportunities.

ACS infectious diseases, 4(2):77-83.

Each year over 3 million people die from infectious diseases with most of these deaths being poor and young children who live in low- and middle-income countries. Infectious diseases emerge for a multitude of reasons. On the social front, reasons include a breakdown of public health standards, international travel, and immigration (for financial, civil, and social reasons). At the molecular level, the modern rise of infectious diseases is tied to the juxtaposition of drug-resistant pathogens and a lack of new antimicrobials. The consequence is the possibility that humankind will return to the preantibiotic era wherein millions of people will perish from what should be trivial illnesses. Given the stakes, it is imperative that the chemistry community take leadership in delivering new antibiotic leads for clinical development. We believe this can happen through innovation in two areas. First is the development of novel chemical scaffolds to treat infections caused by multidrug-resistant pathogens. The second area, which is not exclusive to the first, is the generation of antibiotics that do not cause collateral damage to the host or the host's microbiome. Both can be enabled through advances in chemical synthesis. It is with this general philosophy in mind that we hypothesized human milk oligosaccharides (HMOs) could serve as novel chemical scaffolds for antibacterial development. We provide herein a personal account of our laboratory's progress toward the goal of using HMOs as a defense against infectious diseases.

RevDate: 2019-06-13
CmpDate: 2019-06-11

Chen R, Wang Z, Chen J, et al (2017)

Insect-bacteria parallel evolution in multiple-co-obligate-aphid association: a case in Lachninae (Hemiptera: Aphididae).

Scientific reports, 7(1):10204.

Parallel phylogenies between aphid and its obligate symbiont Buchnera are hot topics which always focused on aphid lower taxonomic levels. Symbionts in the subfamily Lachninae are special. Buchnera in many lachnine species has undergone functional and genome size reduction that was replaced by other co-obligate symbionts. In this study, we constructed the phylogenetic relationships of Lachninae with a combined dataset of five genes sequenced from Buchnera to estimate the effects of a dual symbiotic system in the aphid-Buchnera cospeciation association. The phylogeny of Buchnera in Lachninae was well-resolved in the combined dataset. Each of the genera formed strongly supported monophyletic groups, with the exception of the genus Cinara. The phylogeny based on sequences from Buchnera was divided into five tribes according to the clades of the Lachninae hosts tree, with the phylogenies of Buchnera and Lachninae being generally congruent. These results first provided evidence of parallel evolution at the aphid subfamily level comprehensively and supported the view that topological congruence between the phylogenies of Buchnera and Lachninae would not be interfered with the other co-obligate symbionts, such as Sarretia, in aphid-entosymbiont association. These results also provided new insight in understanding host-plant coevolution in lachnine lineages.

RevDate: 2019-06-12

Guo X, Zhao Z, Mar SS, et al (2019)

A symbiotic balancing act: arbuscular mycorrhizal specificity and specialist fungus gnat pollination in the mycoheterotrophic genus Thismia (Thismiaceae).

Annals of botany pii:5514326 [Epub ahead of print].

BACKGROUND AND AIMS: Mycorrhizal associations in mycoheterotrophic plants are generally more specialized than in autotrophs. Mycoheterotrophs typically bear small, inconspicuous flowers that often self-pollinate to maximize seed set, although some have structurally complex flowers indicative of xenogamy. A trade-off has previously been proposed between specialization in these above- and below-ground symbioses, although empirical data are lacking.

METHODS: We used next-generation DNA sequencing to compare the mycorrhizal communities from the roots of a mycoheterotrophic species, Thismia tentaculata (Thismiaceae), and its neighbouring autotrophs. We furthermore conducted detailed assessments of floral phenology and pollination ecology, and performed artificial pollination experiments to determine the breeding system.

KEY RESULTS: Thismia tentaculata maintains a symbiotic association with a single arbuscular mycorrhizal Rhizophagus species. The flowers are pollinated by a single species of fungus gnats (Corynoptera, Sciaridae), which are attracted by the yellow pigments and are temporarily restrained within the perianth chamber before departing via apertures between the anthers. The plants are self-compatible but predominantly xenogamous.

CONCLUSIONS: Our findings demonstrate that T. tentaculata maintains highly specialized associations with pollinators and mycorrhizal fungi, both of which are widely distributed. We suggest that specialization in multiple symbiotic interactions is possible in mycoheterotrophs if redundant selective pressures are not exerted to further restrict an already constrained suite of life-history traits.

RevDate: 2019-06-12

Gabay Y, Parkinson JE, Wilkinson SP, et al (2019)

Inter-partner specificity limits the acquisition of thermotolerant symbionts in a model cnidarian-dinoflagellate symbiosis.

The ISME journal pii:10.1038/s41396-019-0429-5 [Epub ahead of print].

The ability of corals and other cnidarians to survive climate change depends partly on the composition of their endosymbiont communities. The dinoflagellate family Symbiodiniaceae is genetically and physiologically diverse, and one proposed mechanism for cnidarians to acclimate to rising temperatures is to acquire more thermally tolerant symbionts. However, cnidarian-dinoflagellate associations vary in their degree of specificity, which may limit their capacity to alter symbiont communities. Here, we inoculated symbiont-free polyps of the sea anemone Exaiptasia pallida (commonly referred to as 'Aiptasia'), a model system for the cnidarian-dinoflagellate symbiosis, with simultaneous or sequential mixtures of thermally tolerant and thermally sensitive species of Symbiodiniaceae. We then monitored symbiont success (relative proportional abundance) at normal and elevated temperatures across two to four weeks. All anemones showed signs of bleaching at high temperature. During simultaneous inoculations, the native, thermally sensitive Breviolum minutum colonized polyps most successfully regardless of temperature when paired against the non-native but more thermally tolerant Symbiodinium microadriaticum or Durusdinium trenchii. Furthermore, anemones initially colonized with B. minutum and subsequently exposed to S. microadriaticum failed to acquire the new symbiont. These results highlight how partner specificity may place strong limitations on the ability of certain cnidarians to acquire more thermally tolerant symbionts, and hence their adaptive potential under climate change.

RevDate: 2019-06-12

Chrostek E, M Gerth (2019)

Is Anopheles gambiae a Natural Host of Wolbachia?.

mBio, 10(3): pii:mBio.00784-19.

Wolbachia (Alphaproteobacteria, Rickettsiales) is an intraovarially transmitted symbiont of insects able to exert striking phenotypes, including reproductive manipulations and pathogen blocking. These phenotypes make Wolbachia a promising tool to combat mosquito-borne diseases. Although Wolbachia is present in the majority of terrestrial arthropods, including many disease vectors, it was considered absent from Anopheles gambiae mosquitos, the main vectors of malaria in sub-Saharan Africa. In 2014, Wolbachia sequences were detected in A. gambiae samples collected in Burkina Faso. Subsequently, similar evidence came from collections all over Africa, revealing a high Wolbachia 16S rRNA sequence diversity, low abundance, and a lack of congruence between host and symbiont phylogenies. Here, we reanalyze and discuss recent evidence on the presence of Wolbachia sequences in A. gambiae. We find that although detected at increasing frequencies, the unusual properties of these Wolbachia sequences render them insufficient to diagnose natural infections in A. gambiae Future studies should focus on uncovering the origin of Wolbachia sequence variants in Anopheles and seeking sequence-independent evidence for this new symbiosis. Understanding the ecology of Anopheles mosquitos and their interactions with Wolbachia will be key in designing successful, integrative approaches to limit malaria spread. Although the prospect of using Wolbachia to fight malaria is intriguing, the newly discovered strains do not bring it closer to realization.IMPORTANCEAnopheles gambiae mosquitos are the main vectors of malaria, threatening around half of the world's population. The bacterial symbiont Wolbachia can interfere with disease transmission by other important insect vectors, but until recently, it was thought to be absent from natural A. gambiae populations. Here, we critically analyze the genomic, metagenomic, PCR, imaging, and phenotypic data presented in support of the presence of natural Wolbachia infections in A. gambiae We find that they are insufficient to diagnose Wolbachia infections and argue for the need of obtaining robust data confirming basic Wolbachia characteristics in this system. Determining the Wolbachia infection status of Anopheles is critical due to its potential to influence Anopheles population structure and Plasmodium transmission.

RevDate: 2019-06-12

Septer AN (2019)

The Vibrio-Squid Symbiosis as a Model for Studying Interbacterial Competition.

mSystems, 4(3): pii:4/3/e00108-19.

The symbiosis between Euprymna scolopes squid and its bioluminescent bacterial symbiont, Vibrio fischeri, is a valuable model system to study a natural, coevolved host-microbe association. Over the past 30 years, researchers have developed and optimized many experimental methods to study both partners in isolation and during symbiosis. These powerful tools, along with a strong foundational knowledge about the system, position the Vibrio-squid symbiosis at the forefront of host-microbe interactions because this system is uniquely suited to investigation of symbiosis from both host and bacterial perspectives. Moreover, the ability to isolate and characterize different strains of V. fischeri has revealed exciting new insights about how different genotypes evolve to compete for a host niche, including deploying interbacterial weapons early during host colonization. This Perspective explores how interbacterial warfare influences the diversity and spatial structure of the symbiotic population, as well as the possible effects that intraspecific competition might have on the host.

RevDate: 2019-06-11

Gomes DF, Tullio LD, Del Cerro P, et al (2019)

Regulation of hsnT, nodF and nodE genes in Rhizobium tropici CIAT 899 and their roles in the synthesis of Nod factors and in the symbiosis.

Microbiology (Reading, England) [Epub ahead of print].

Rhizobium tropici strain CIAT 899 possesses outstanding agronomic properties as it displays tolerance to environmental stresses, a broad host range and high effectiveness in fixing nitrogen with the common bean (Phaseolus vulgaris L.); in addition, it carries intriguing features such as five copies of the regulatory nodD gene, and the capacity to synthesize a variety of nodulation factors (NFs), even in a flavonoid-independent manner, when submitted to abiotic stresses. However, the roles of several nod genes of the repertoire of CIAT 899 remain to be determined. In this study, we obtained mutants for the hsnT, nodF and nodE genes of CIAT 899 and investigated their expression, NF structures and symbiotic properties. Either in the presence of the flavonoid apigenin, or of salt the expression of hsnT, nodF and nodE in wild-type CIAT 899 was highly up-regulated in comparison to the mutants of all five copies of nodD, indicating the roles that regulatory nodD genes play in the activation of hsnT, nodF and nodE; however, NodD1 was recognized as the main inducer. In total, 29 different NF structures were synthesized by wild-type CIAT 899 induced by apigenin, and 36 when induced by salt, being drastically reduced by mutations in hsnT, nodF and nodE, especially under osmotic stress, with specific changes related to each gene, indicating that the three genes participate in the synthesis of NFs. Mutations in hsnT, nodF and nodE affected differently symbiotic performance (nodule number and shoot dry weight), according to the host plant. Our results indicate that the expression of hsnT, nodF and nodE genes of CIAT 899 is mediated by nodD genes, and although these three genes do not belong to the main set of genes controlling nodulation, they contribute to the synthesis of NFs that will impact symbiotic performance and host specificity.

RevDate: 2019-06-11

Gruber-Vodicka HR, Leisch N, Kleiner M, et al (2019)

Two intracellular and cell type-specific bacterial symbionts in the placozoan Trichoplax H2.

Nature microbiology pii:10.1038/s41564-019-0475-9 [Epub ahead of print].

Placozoa is an enigmatic phylum of simple, microscopic, marine metazoans1,2. Although intracellular bacteria have been found in all members of this phylum, almost nothing is known about their identity, location and interactions with their host3-6. We used metagenomic and metatranscriptomic sequencing of single host individuals, plus metaproteomic and imaging analyses, to show that the placozoan Trichoplax sp. H2 lives in symbiosis with two intracellular bacteria. One symbiont forms an undescribed genus in the Midichloriaceae (Rickettsiales)7,8 and has a genomic repertoire similar to that of rickettsial parasites9,10, but does not seem to express key genes for energy parasitism. Correlative image analyses and three-dimensional electron tomography revealed that this symbiont resides in the rough endoplasmic reticulum of its host's internal fibre cells. The second symbiont belongs to the Margulisbacteria, a phylum without cultured representatives and not known to form intracellular associations11-13. This symbiont lives in the ventral epithelial cells of Trichoplax, probably metabolizes algal lipids digested by its host and has the capacity to supplement the placozoan's nutrition. Our study shows that one of the simplest animals has evolved highly specific and intimate associations with symbiotic, intracellular bacteria and highlights that symbioses can provide access to otherwise elusive microbial dark matter.

RevDate: 2019-06-11

Lamouche F, Chaumeret A, Guefrachi I, et al (2019)

From intracellular bacteria to differentiated bacteroids: transcriptome and metabolome analysis in Aeschynomene nodules using the Bradyrhizobium sp. ORS285 bclA mutant.

Journal of bacteriology pii:JB.00191-19 [Epub ahead of print].

Soil bacteria called rhizobia trigger the formation of root nodules on legume plants. The rhizobia infect these symbiotic organs and adopt an intracellular lifestyle within the nodule cells where they differentiate into nitrogen-fixing bacteroids. Several legume lineages enforce their symbionts into an extreme cellular differentiation, comprising cell enlargement and genome endoreduplication. The antimicrobial peptide transporter BclA is a major determinant of this process in Bradyrhizobium sp. ORS285, a symbiont of Aeschynomene spp.. In the absence of BclA, the bacteria proceed until the intracellular infection of nodule cells but they cannot differentiate into enlarged polyploid and functional bacteroids. The bclA nodule bacteria constitute thus an intermediate stage between the free-living soil bacteria and the nitrogen-fixing bacteroids. Metabolomics on whole nodules of Aeschynomene afraspera and Aeschynomene indica infected with the wild type or the bclA mutant revealed 47 metabolites that differentially accumulated concomitantly with bacteroid differentiation. Bacterial transcriptome analysis of these nodules demonstrated that the intracellular settling of the rhizobia in the symbiotic nodule cells is accompanied with a first transcriptome switch involving several hundreds of upregulated and downregulated genes and a second switch accompanying the bacteroid differentiation, involving less genes but ones that are expressed to extremely elevated levels. The transcriptomes further suggested a dynamic role for oxygen and redox regulation of gene expression during nodule formation and a non-symbiotic function of BclA. Together, our data uncover the metabolic and gene expression changes that accompany the transition from intracellular bacteria into differentiated nitrogen-fixing bacteroids.ImportanceThe legume-rhizobium symbiosis is a major ecological process fueling the biogeochemical nitrogen cycle with reduced nitrogen. It represents also a promising strategy to cut down the use of chemical nitrogen fertilizers in agriculture, thereby improving its sustainability. This interaction leads to the intracellular accommodation of rhizobia within plant cells of symbiotic organs where they differentiate into nitrogen-fixing bacteroids. In specific legume clades, this differentiation process requires the bacterial transporter BclA to counteract antimicrobial peptides produced by the host. Transcriptome analysis of Bradyrhizobium wild-type and bclA mutant bacteria in culture and in symbiosis with Aeschynomene host plants dissected the bacterial transcriptional response in distinct phases and highlighted functions of the transporter in the free-living stage of the bacterial life cycle.

RevDate: 2019-06-11

Strohm E, Herzner G, Ruther J, et al (2019)

Nitric oxide radicals are emitted by wasp eggs to kill mold fungi.

eLife, 8: pii:43718.

Detrimental microbes caused the evolution of a great diversity of antimicrobial defenses in plants and animals. Insects developing underground seem particularly threatened. Here we show that the eggs of a solitary digger wasp, the European beewolf Philanthus triangulum, emit large amounts of gaseous nitric oxide (NO⋅) to protect themselves and their provisions, paralyzed honeybees, against mold fungi. We provide evidence that a NO-synthase (NOS) is involved in the generation of the extraordinary concentrations of nitrogen radicals in brood cells (~1500 ppm NO⋅ and its oxidation product NO2⋅). Sequencing of the beewolf NOS gene revealed no conspicuous differences to related species. However, due to alternative splicing, the NOS-mRNA in beewolf eggs lacks an exon near the regulatory domain. This preventive external application of high doses of NO⋅ by wasp eggs represents an evolutionary key innovation that adds a remarkable novel facet to the array of functions of the important biological effector NO⋅.

RevDate: 2019-06-11

Hao Z, Xie W, B Chen (2019)

Arbuscular Mycorrhizal Symbiosis Affects Plant Immunity to Viral Infection and Accumulation.

Viruses, 11(6): pii:v11060534.

Arbuscular mycorrhizal (AM) fungi, as root symbionts of most terrestrial plants, improve plant growth and fitness. In addition to the improved plant nutritional status, the physiological changes that trigger metabolic changes in the root via AM fungi can also increase the host ability to overcome biotic and abiotic stresses. Plant viruses are one of the important limiting factors for the commercial cultivation of various crops. The effect of AM fungi on viral infection is variable, and considerable attention is focused on shoot virus infection. This review provides an overview of the potential of AM fungi as bioprotection agents against viral diseases and emphasizes the complex nature of plant-fungus-virus interactions. Several mechanisms, including modulated plant tolerance, manipulation of induced systemic resistance (ISR), and altered vector pressure are involved in such interactions. We propose that using "omics" tools will provide detailed insights into the complex mechanisms underlying mycorrhizal-mediated plant immunity.

RevDate: 2019-06-11

Ho YS (2019)

Comment to: Qi, Yi, et al. "Bibliometric Analysis of Algal-Bacterial Symbiosis in Wastewater Treatment", Int. J. Environ. Res. Public Health 2019, 16, 1077.

International journal of environmental research and public health, 16(11): pii:ijerph16112034.

Qi et al. recently published an article in the journal, entitled "Bibliometric Analysis of Algal-Bacterial Symbiosis in Wastewater Treatment" [...].

RevDate: 2019-06-10

Thapa V, MJ Roossinck (2019)

Determinants of Coinfection in the Mycoviruses.

Frontiers in cellular and infection microbiology, 9:169.

RevDate: 2019-06-10

Whiteside MD, Werner GDA, Caldas VEA, et al (2019)

Mycorrhizal Fungi Respond to Resource Inequality by Moving Phosphorus from Rich to Poor Patches across Networks.

Current biology : CB pii:S0960-9822(19)30490-7 [Epub ahead of print].

The world's ecosystems are characterized by an unequal distribution of resources [1]. Trade partnerships between organisms of different species-mutualisms-can help individuals cope with such resource inequality [2-4]. Trade allows individuals to exchange commodities they can provide at low cost for resources that are otherwise impossible or more difficult to access [5, 6]. However, as resources become increasingly patchy in time or space, it is unknown how organisms alter their trading strategies [7, 8]. Here, we show how a symbiotic fungus mediates trade with a host root in response to different levels of resource inequality across its network. We developed a quantum-dot-tracking technique to quantify phosphorus-trading strategies of arbuscular mycorrhizal fungi simultaneously exposed to rich and poor resource patches. By following fluorescent nanoparticles of different colors across fungal networks, we determined where phosphorus was hoarded, relocated, and transferred to plant hosts. We found that increasing exposure to inequality stimulated trade. Fungi responded to high resource variation by (1) increasing the total amount of phosphorus distributed to host roots, (2) decreasing allocation to storage, and (3) differentially moving resources within the network from rich to poor patches. Using single-particle tracking and high-resolution video, we show how dynamic resource movement may help the fungus capitalize on value differences across the trade network, physically moving resources to areas of high demand to gain better returns. Such translocation strategies can help symbiotic organisms cope with exposure to resource inequality.

RevDate: 2019-06-10

Spagnoletti FN, VM Chiocchio (2019)

Tolerance of dark septate endophytic fungi (DSE) to agrochemicals in vitro.

Revista Argentina de microbiologia pii:S0325-7541(19)30027-6 [Epub ahead of print].

Dark septate endophytes (DSE) are a heterogeneous group of fungi, mostly belonging to the Phylum Ascomycota, that are involved in a mutualistic symbiosis with plant roots. The aim of this study is to evaluate the behavior of two strains of DSE isolated from wheat roots of two cropping areas in the province of Buenos Aires, Argentina, against some agrochemicals. Of all the isolates obtained, two strains were identified as Alternaria alternata and Cochliobolus sp. These DSE were found to be tolerant to glyphosate, carbendazim and cypermethrin when evaluated at the recommended agronomic dose (AD), 2 AD and, in some cases, 10 AD. This work contributes to the study of the biology of this group of fungi and their tolerance in the presence of xenobiotics widely used in agriculture.


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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E-mail: RJR8222@gmail.com

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

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Curriculum Vitae for R J Robbins

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