About | BLOGS | Portfolio | Misc | Recommended | What's New | What's Hot

About | BLOGS | Portfolio | Misc | Recommended | What's New | What's Hot


Bibliography Options Menu

18 Aug 2019 at 01:35
Hide Abstracts   |   Hide Additional Links
Long bibliographies are displayed in blocks of 100 citations at a time. At the end of each block there is an option to load the next block.

Bibliography on: Symbiosis


Robert J. Robbins is a biologist, an educator, a science administrator, a publisher, an information technologist, and an IT leader and manager who specializes in advancing biomedical knowledge and supporting education through the application of information technology. More About:  RJR | OUR TEAM | OUR SERVICES | THIS WEBSITE

RJR: Recommended Bibliography 18 Aug 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."

Created with PubMed® Query: symbiosis NOT pmcbook NOT ispreviousversion

Citations The Papers (from PubMed®)

RevDate: 2019-08-16

Ikuta T, Tame A, Saito M, et al (2019)

Identification of cells expressing two peptidoglycan recognition proteins in the gill of the vent mussel, Bathymodiolus septemdierum.

Fish & shellfish immunology pii:S1050-4648(19)30822-8 [Epub ahead of print].

In symbiotic systems in which symbionts are transmitted horizontally, hosts must accept symbionts from the environment while defending themselves against invading pathogenic microorganisms. How they distinguish pathogens from symbionts and how the latter evade host immune defences are not clearly understood. Recognition of foreign materials is one of the most critical steps in stimulating immune responses, and pattern recognition receptors (PRRs) play vital roles in this process. In this study, we focused on a group of highly conserved PRRs, peptidoglycan recognition proteins (PGRPs), in the deep-sea mussel, Bathymodiolus septemdierum, which harbour chemosynthetic bacteria in their gill epithelial cells. We isolated B. septemdierum PGRP genes BsPGRP-L and BsPGRP-S, which encode a short- and a long-type PGRP, respectively. The short-type PGRP has a signal peptide and was expressed in the asymbiotic goblet mucous cells in the gill epithelium, whereas the long-type PGRP was predicted to include a transmembrane domain and was expressed in gill bacteriocytes. Based on these findings, we hypothesize that the secreted and transmembrane PGRPs are engaged in host defence against pathogenic bacteria and/or in the regulation of symbiosis via different cellular localizations and mechanisms.

RevDate: 2019-08-16

Liu X, Tang K, Zhang D, et al (2019)

Symbiosis of a P2-Family Phage and Deep-Sea Shewanella putrefaciens.

Environmental microbiology [Epub ahead of print].

Almost all bacterial genomes harbor prophages yet it remains unknown why prophages integrate into tRNA-related genes. Approximately 1/3 of Shewanella isolates harbor a prophage at the tmRNA (ssrA) gene. Here, we discovered a P2-family prophage integrated at the 3'-end of ssrA in the deep-sea bacterium S. putrefaciens. We found that ~0.1% of host cells are lysed to release P2 constitutively during host growth. P2 phage production is induced by a prophage-encoded Rep protein and its excision is induced by the Cox protein. We also found that P2 genome excision leads to the disruption of wobble base pairing of SsrA due to site-specific recombination, thus disrupting the trans-translation function of SsrA. We further demonstrated that P2 excision greatly hinders growth in sea water medium and inhibits biofilm formation. Complementation with a functional SsrA in the P2-excised strain completely restores the growth defects in sea water medium and partially restores biofilm formation. Additionally, we found that products of the P2 genes also increase biofilm formation. Taken together, this study illustrates a symbiotic relationship between P2 and its marine host, thus providing multiple benefits for both sides when a phage is integrated but suffers from reduced fitness when the prophage is excised. This article is protected by copyright. All rights reserved.

RevDate: 2019-08-16

Chen Q, Wu WW, Qi SS, et al (2019)

Arbuscular mycorrhizal fungi improve the growth and disease resistance of the invasive plant Wedelia trilobata.

Journal of applied microbiology [Epub ahead of print].

AIMS: Arbuscular mycorrhizal fungi (AMF) are symbiotic partners of many invasive plants, however it is still unclear how AMF contribute to traits that are important for the successful invasion of their host and how environmental factors, such as nutrient conditions, influence this. This study was to explore the effects of Glomus versiforme (GV) and Glomus mosseae (GM) on the growth and disease resistance of the invasive plant Wedelia trilobata under different nutrient conditions.

METHODS AND RESULTS: We found that GV and GM had higher root colonization rates resulting in faster W. trilobata growth under both low-N and low-P nutrient conditions compared to the normal condition. Also, the colonization of W. trilobata by GV significantly reduced the infection area of the pathogenic fungus Rhizoctonia solani under low-N conditions.

CONCLUSIONS: These results demonstrated that AMF can promote the growth and pathogenic defense of W. trilobata in a nutrient-poor environment, which might contribute to their successful invasion into certain type of habitats.

In this study, we report for the first time that AMF can promote growth and disease resistance of W. trilobata under nutrient-poor environment, which contribute to a better understanding of plant invasion. This article is protected by copyright. All rights reserved.

RevDate: 2019-08-16

Andryuschenko SV, Ivanova EV, Perunova NB, et al (2019)

Genome Sequence and Biochemical Properties of Bifidobacterium longum Strain ICIS-505, Isolated from the Intestine of a Healthy Woman.

Microbiology resource announcements, 8(33): pii:8/33/e00491-19.

This report describes the genome sequence of Bifidobacterium longum strain ICIS-505, isolated from human feces. The size of the genome was 2,448,844 bp (59.71% G+C content), including 3,751 bp of the crypto-plasmid pBL505. Annotation revealed 2,241 gene sequences, including 2,033 proteins, 7 rRNA genes, 76 tRNA genes, and 4 noncoding RNA genes.

RevDate: 2019-08-16

Cope KR, Bascaules A, Irving TB, et al (2019)

The Ectomycorrhizal Fungus Laccaria bicolor Produces Lipochitooligosaccharides and Uses the Common Symbiosis Pathway to Colonize Populus Roots.

The Plant cell pii:tpc.18.00676 [Epub ahead of print].

Mycorrhizal fungi form mutualistic associations with the roots of most land plants and provide them with mineral nutrients from the soil in exchange for fixed carbon derived from photosynthesis. The common symbiosis pathway (CSP) is a conserved molecular signaling pathway in all plants capable of associating with arbuscular mycorrhizal fungi . It is required not only for arbuscular mycorrhizal symbiosis but also for rhizobia-legume and actinorhizal symbioses. Given its role in such diverse symbiotic associations, we hypothesized that the CSP also plays a role in ectomycorrhizal associations. We showed that the ectomycorrhizal fungus Laccaria bicolor produces an array of lipochitooligosaccharides (LCOs) that can trigger both root hair branching in legumes and, most importantly, calcium spiking in the host plant Populus in a CASTOR/POLLUX-dependent manner. Nonsulfated LCOs enhanced lateral root development in Populus in a CCaMK-dependent manner, and sulfated LCOs enhanced the colonization of Populus by L. bicolor. Compared to wild-type Populus, the colonization of CASTOR/POLLUX and CCaMK RNA interference lines by L. bicolor was reduced. Our work demonstrates that similar to other root symbioses, L. bicolor uses the CSP for the full establishment of its mutualistic association with Populus.

RevDate: 2019-08-16

Černajová I, P Škaloud (2019)

The first survey of Cystobasidiomycete yeasts in the lichen genus Cladonia; with the description of Lichenozyma pisutiana gen. nov., sp. nov.

Fungal biology, 123(9):625-637.

The view of lichens as a symbiosis only between a mycobiont and a photobiont has been challenged by discoveries of diverse associated organisms. Specific basidiomycete yeasts in the cortex of a range of macrolichens were hypothesized to influence the lichens' phenotype. The present study explores the occurrence and diversity of cystobasidiomycete yeasts in the lichen genus Cladonia. We obtained seven cultures and 56 additional sequences using specific primers from 27 Cladonia species from all over Europe and performed phylogenetic analyses based on ITS, LSU and SSU rDNA loci. We revealed yeast diversity distinct from any previously reported. Representatives of Cyphobasidiales, Microsporomycetaceae and of an unknown group related to Symmetrospora have been found. We present evidence that the Microsporomycetaceae contains mainly lichen-associated yeasts. Lichenozyma pisutiana is circumscribed here as a new genus and species. We report the first known associations between cystobasidiomycete yeasts and Cladonia (both corticate and ecorticate), and find that the association is geographically widespread in various habitats. Our results also suggest that a great diversity of lichen associated yeasts remains to be discovered.

RevDate: 2019-08-16

Yang QS, Dong JD, Ahmad M, et al (2019)

Analysis of nifH DNA and RNA reveals a disproportionate contribution to nitrogenase activities by rare plankton-associated diazotrophs.

BMC microbiology, 19(1):188 pii:10.1186/s12866-019-1565-9.

BACKGROUND: Holobionts comprising nitrogen-fixing diazotrophs and phytoplankton or zooplankton are ubiquitous in the pelagic sea. However, neither the community structure of plankton-associated diazotrophs (PADs) nor their nitrogenase transcriptional activity are well-understood. In this study, we used nifH gene Illumina sequencing and quantitative PCR to characterize the community composition and nifH expression profile of PADs with > 100 μm size fraction in the euphotic zone of the northern South China Sea.

RESULTS: The results of DNA- and RNA-derived nifH gene revealed a higher alpha-diversity in the active than in the total community. Moreover, the compositional resemblance among different sites was less for active than for total communities of PADs. We characterized the 20 most abundant OTUs by ranking the sum of sequence reads across 9 sampling stations for individual OTUs in both nifH DNA and RNA libraries, and then assessed their phylogenetic relatedness. Eight of the 20 abundant OTUs were phylogenetically affiliated with Trichodesmium and occurred in approximately equal proportion in both the DNA and RNA libraries. The analysis of nifH gene expression level showed uneven attribute of the abundance and nitrogenase activities by the remaining 12 OTUs. Taxa belonging to cluster III and Betaproteobacteria were present at moderate abundance but exhibited negligible nitrogenase transcription activity. Whereas, the abundances of Richelia, Deltaproteobacteria and Gammaproteobacteria were low but the contribution of these groups to nitrogenase transcription was disproportionately high.

CONCLUSIONS: The substantial variation in community structure among active dizatrophic fractions compared to the total communities suggests that the former are better indicators of biological response to environmental changes. Altogether, our study highlights the importance of rare PADs groups in nitrogen fixation in plankton holobionts, evidenced by their high level of nitrogenase transcription.

RevDate: 2019-08-16
CmpDate: 2019-08-16

Helgadóttir Á, Suter M, Gylfadóttir TÓ, et al (2018)

Grass-legume mixtures sustain strong yield advantage over monocultures under cool maritime growing conditions over a period of 5 years.

Annals of botany, 122(2):337-348.

Background and Aims: Grassland-based livestock systems in cool maritime regions are commonly dominated by grass monocultures receiving relatively high levels of fertilizer. The current study investigated whether grass-legume mixtures can improve the productivity, resource efficiency and robustness of yield persistence of cultivated grassland under extreme growing conditions over a period of 5 years.

Methods: Monocultures and mixtures of two grasses (Phleum pratense and Festuca pratensis) and two legumes (Trifolium pratense and Trifolium repens), one of which was fast establishing and the other temporally persistent, were sown in a field trial. Relative abundance of the four species in the mixtures was systematically varied at sowing. The plots were maintained under three N levels (20, 70 and 220 kg N ha-1 year-1) and harvested twice a year for five consecutive years. Yields of individual species and interactions between all species present were modelled to estimate the species diversity effects.

Key Results: Significant positive diversity effects in all individual years and averaged across the 5 years were observed. Across years, the four-species equi-proportional mixture was 71 % (N20: 20 kg N ha-1 year-1) and 51 % (N70: 70 kg N ha-1 year-1) more productive than the average of monocultures, and the highest yielding mixture was 36 % (N20) and 39 % (N70) more productive than the highest yielding monoculture. Importantly, diversity effects were also evident at low relative abundances of either species group, grasses or legumes in the mixture. Mixtures suppressed weeds significantly better than monocultures consistently during the course of the experiment at all N levels.

Conclusions: The results show that even in the less productive agricultural systems in the cool maritime regions grass-legume mixtures can contribute substantially and persistently to a more sustainable agriculture. Positive grass-legume interactions suggest that symbiotic N2 fixation is maintained even under these marginal conditions, provided that adapted species and cultivars are used.

RevDate: 2019-08-16
CmpDate: 2019-08-16

Bach JF (2018)

The hygiene hypothesis in autoimmunity: the role of pathogens and commensals.

Nature reviews. Immunology, 18(2):105-120.

The incidence of autoimmune diseases has been steadily rising. Concomitantly, the incidence of most infectious diseases has declined. This observation gave rise to the hygiene hypothesis, which postulates that a reduction in the frequency of infections contributes directly to the increase in the frequency of autoimmune and allergic diseases. This hypothesis is supported by robust epidemiological data, but the underlying mechanisms are unclear. Pathogens are known to be important, as autoimmune disease is prevented in various experimental models by infection with different bacteria, viruses and parasites. Gut commensal bacteria also play an important role: dysbiosis of the gut flora is observed in patients with autoimmune diseases, although the causal relationship with the occurrence of autoimmune diseases has not been established. Both pathogens and commensals act by stimulating immunoregulatory pathways. Here, I discuss the importance of innate immune receptors, in particular Toll-like receptors, in mediating the protective effect of pathogens and commensals on autoimmunity.

RevDate: 2019-08-15

Ruszkiewicz JA, Tinkov AA, Skalny AV, et al (2019)

Brain diseases in changing climate.

Environmental research, 177:108637 pii:S0013-9351(19)30434-7 [Epub ahead of print].

Climate change is one of the biggest and most urgent challenges for the 21st century. Rising average temperatures and ocean levels, altered precipitation patterns and increased occurrence of extreme weather events affect not only the global landscape and ecosystem, but also human health. Multiple environmental factors influence the onset and severity of human diseases and changing climate may have a great impact on these factors. Climate shifts disrupt the quantity and quality of water, increase environmental pollution, change the distribution of pathogens and severely impacts food production - all of which are important regarding public health. This paper focuses on brain health and provides an overview of climate change impacts on risk factors specific to brain diseases and disorders. We also discuss emerging hazards in brain health due to mitigation and adaptation strategies in response to climate changes.

RevDate: 2019-08-15

Cheng YT, Zhang L, SY He (2019)

Plant-Microbe Interactions Facing Environmental Challenge.

Cell host & microbe, 26(2):183-192.

In the past four decades, tremendous progress has been made in understanding how plants respond to microbial colonization and how microbial pathogens and symbionts reprogram plant cellular processes. In contrast, our knowledge of how environmental conditions impact plant-microbe interactions is less understood at the mechanistic level, as most molecular studies are performed under simple and static laboratory conditions. In this review, we highlight research that begins to shed light on the mechanisms by which environmental conditions influence diverse plant-pathogen, plant-symbiont, and plant-microbiota interactions. There is a great need to increase efforts in this important area of research in order to reach a systems-level understanding of plant-microbe interactions that are more reflective of what occurs in nature.

RevDate: 2019-08-15

Boem F, A Amedei (2019)

Healthy axis: Towards an integrated view of the gut-brain health.

World journal of gastroenterology, 25(29):3838-3841.

Despite the lack of precise mechanisms of action, a growing number of studies suggests that gut microbiota is involved in a great number of physiological functions of the human organism. In fact, the composition and the relations of intestinal microbial populations play a role, either directly or indirectly, to both the onset and development of various pathologies. In particular, the gastrointestinal tract and nervous system are closely connected by the so-called gut-brain axis, a complex bidirectional system in which the central and enteric nervous system interact with each other, also engaging endocrine, immune and neuronal circuits. This allows us to put forward new working hypotheses on the origin of some multifactorial diseases: from eating to neuropsychiatric disorders (such as autism spectrum disorders and depression) up to diabetes and tumors (such as colorectal cancer). This scenario reinforces the idea that the microbiota and its composition represent a factor, which is no longer negligible, not only in preserving what we call "health" but also in defining and thus determining it. Therefore, we propose to consider the gut-brain axis as the focus of new scientific and clinical investigation as long as the locus of possible systemic therapeutic interventions.

RevDate: 2019-08-15
CmpDate: 2019-08-15

Vila A, Estrada-Peña A, Altet L, et al (2019)

Endosymbionts carried by ticks feeding on dogs in Spain.

Ticks and tick-borne diseases, 10(4):848-852.

Studies on tick microbial communities historically focused on tick-borne pathogens. However, there is an increasing interest in capturing relationships among non-pathogenic endosymbionts and exploring their relevance for tick biology. The present study included a total of 1600 adult ticks collected from domestic dogs in 4 different biogeographical regions of Spain. Each pool formed by 1 to 10 halves of individuals representing one specific ticks species was examined by PCR for the presence of Coxiellaceae, Rickettsia spp., Rickettsiales, Wolbachia spp., and other bacterial DNA. Of the pools analyzed, 92% tested positive for endosymbiont-derived DNA. Coxiella spp. endosymbionts were the most prevalent microorganisms, being always present in Rhipicephalus sanguineus sensu lato (s.l.) pools. Rickettsia spp. DNA was detected in 60% of Dermacentor reticulatus pools and 40% of R. sanguineus s.l. pools, with a higher diversity of Rickettsia species in R. sanguineus s.l. pools. Our study reveals a negative relationship of Rickettsia massiliae with the presence of tick-borne pathogens in the same pool of ticks. An additional endosymbiont, 'Candidatus Rickettsiella isopodorum', was only detected in D. reticulatus pools. Data from this study indicate that dogs in Spain are exposed to several endosymbionts. Due to the importance of tick-borne pathogens, characterizing the role of endosymbionts for tick physiology and prevalence, may lead to novel control strategies.

RevDate: 2019-08-15
CmpDate: 2019-08-15

Santana JO, Gramacho KP, de Souza Eduvirgens Ferreira KT, et al (2018)

Witches' broom resistant genotype CCN51 shows greater diversity of symbiont bacteria in its phylloplane than susceptible genotype catongo.

BMC microbiology, 18(1):194.

BACKGROUND: Theobroma cacao L. (cacao) is a perennial tropical tree, endemic to rainforests of the Amazon Basin. Large populations of bacteria live on leaf surfaces and these phylloplane microorganisms can have important effects on plant health. In recent years, the advent of high-throughput sequencing techniques has greatly facilitated studies of the phylloplane microbiome. In this study, we characterized the bacterial microbiome of the phylloplane of the catongo genotype (susceptible to witch's broom) and CCN51 (resistant). Bacterial microbiome was determined by sequencing the V3-V4 region of the bacterial 16S rRNA gene.

RESULTS: After the pre-processing, a total of 1.7 million reads were considered. In total, 106 genera of bacteria were characterized. Proteobacteria was the predominant phylum in both genotypes. The exclusive genera of Catongo showed activity in the protection against UV radiation and in the transport of substrates. CCN51 presented genus that act in the biological control and inhibition in several taxonomic groups. Genotype CCN51 presented greater diversity of microorganisms in comparison to the Catongo genotype and the total community was different between both. Scanning electron microscopy analysis of leaves revealed that on the phylloplane, many bacterial occur in large aggregates in several regions of the surface and isolated nearby to the stomata.

CONCLUSIONS: We describe for the first time the phylloplane bacterial communities of T. cacao. The Genotype CCN51, resistant to the witch's broom, has a greater diversity of bacterial microbioma in comparison to Catongo and a greater amount of exclusive microorganisms in the phylloplane with antagonistic action against phytopathogens.

RevDate: 2019-08-15
CmpDate: 2019-08-15

Hashmi TR, Devi SR, Ahmad A, et al (2019)

Genetic Status and Endosymbionts Diversity of Bemisia tabaci (Gennadius) on Hosts Belonging to Family Malvaceae in India.

Neotropical entomology, 48(2):207-218.

A study was instigated to examine the genetic status and distribution of known endosymbionts namely Portiera, Rickettsia, Wolbachia, Cardinium, and Arsenophonus in the populations of Bemisia tabaci (Gennadius) from three host plants: cotton (Gossypium herbaceum), okra (Abelmoschus esculentus L.), and China rose (Hibiscus rosa-sinensis) belonging to the family Malvaceae. The presence of four secondary endosymbionts Rickettsia, Wolbachia, Cardinium, and Arsenophonus was checked in Bemisia tabaci populations. Phylogenetic analyses grounded on the mitochondrial cytochrome oxidase I gene (mtCO1) unveiled the presence of Asia 1, Asia II 1, and Asia II 7 genetic groups for Bemisia tabaci on abovementioned crops. Individuals were examined for symbiotic bacterial infection with specific primers amplifying the 16S rRNA gene for Portiera, Rickettsia, Cardinium, and Wolbachia, and the 23S rRNA gene for Arsenophonus. The results show that Portiera was present in all the Bemisia tabaci samples. However, variations were noted in the circulation frequencies of secondary endosymbionts among the Bemisia tabaci populations. A significant difference was noticed in the distribution frequency of Rickettsia between cotton and China rose or okra with their p values as 0.016 and 0.033 respectively. The uneven incidence of secondary endosymbionts ropes the assumption that each endosymbiotic bacterium not only has a role in the endurance but may contribute to the polyphagous nature of Bemisia tabaci. It also brings an uncomplicated evidence for progressive studies on control measures of this notorious insect pest.

RevDate: 2019-08-14

McIntire PJ (2019)

Mankind and the machine: A relationship of symbiosis or conflict?.

RevDate: 2019-08-14

Salloum MS, Insani M, Monteoliva MI, et al (2019)

Metabolic responses to arbuscular mycorrhizal fungi are shifted in roots of contrasting soybean genotypes.

Mycorrhiza pii:10.1007/s00572-019-00909-y [Epub ahead of print].

Modern breeding programs have reduced genetic variability and might have caused a reduction in plant colonization by arbuscular mycorrhizal fungi (AM). In our previous studies, mycorrhizal colonization was affected in improved soybean genotypes, mainly arbuscule formation. Despite substantial knowledge of the symbiosis-related changes of the transcriptome and proteome, only sparse clues regarding metabolite alterations are available. Here, we evaluated metabolite changes between improved (I-1) and unimproved (UI-4) soybean genotypes and also compare their metabolic responses after AM root colonization. Soybean genotypes inoculated or not with AM were grown in a chamber under controlled light and temperature conditions. At 20 days after inoculation, we evaluated soluble metabolites of each genotype and treatment measured by GC-MS. In this analysis, when comparing non-AM roots between genotypes, I-1 had a lower amount of 31 and higher amount of only 4 metabolites than the UI-4 genotype. When comparing AM roots, I-1 had a lower amount of 36 and higher amount of 4 metabolites than UI-4 (different to those found altered in non-AM treated plants). Lastly, comparing the AM vs non-AM treatments, I-1 had increased levels of three and reduced levels of 24 metabolites, while UI-4 only had levels of 12 metabolites reduced by the effect of mycorrhizas. We found the major changes in sugars, polyols, amino acids, and carboxylic acids. In a targeted analysis, we found lower levels of isoflavonoids and alpha-tocopherol and higher levels of malondialdehyde in the I-1 genotype that can affect soybean-AM symbiosis. Our studies have the potential to support improving soybean with a greater capacity to be colonized and responsive to AM interaction.

RevDate: 2019-08-14

Zhang S, Song W, Wemheuer B, et al (2019)

Comparative Genomics Reveals Ecological and Evolutionary Insights into Sponge-Associated Thaumarchaeota.

mSystems, 4(4): pii:4/4/e00288-19.

Thaumarchaeota are frequently reported to associate with marine sponges (phylum Porifera); however, little is known about the features that distinguish them from their free-living thaumarchaeal counterparts. In this study, thaumarchaeal metagenome-assembled genomes (MAGs) were reconstructed from metagenomic data sets derived from the marine sponges Hexadella detritifera, Hexadella cf. detritifera, and Stylissa flabelliformis Phylogenetic and taxonomic analyses revealed that the three thaumarchaeal MAGs represent two new species within the genus Nitrosopumilus and one novel genus, for which we propose the names "CandidatusUNitrosopumilus hexadellus," "CandidatusUNitrosopumilus detritiferus," and "CandidatusUCenporiarchaeum stylissum" (the U superscript indicates that the taxon is uncultured). Comparison of these genomes to data from the Sponge Earth Microbiome Project revealed that "CaUCenporiarchaeum stylissum" has been exclusively detected in sponges and can hence be classified as a specialist, while "CaUNitrosopumilus detritiferus" and "CaUNitrosopumilus hexadellus" are also detected outside the sponge holobiont and likely lead a generalist lifestyle. Comparison of the sponge-associated MAGs to genomes of free-living Thaumarchaeota revealed signatures that indicate functional features of a sponge-associated lifestyle, and these features were related to nutrient transport and metabolism, restriction-modification, defense mechanisms, and host interactions. Each species exhibited distinct functional traits, suggesting that they have reached different stages of evolutionary adaptation and/or occupy distinct ecological niches within their sponge hosts. Our study therefore offers new evolutionary and ecological insights into the symbiosis between sponges and their thaumarchaeal symbionts.IMPORTANCE Sponges represent ecologically important models to understand the evolution of symbiotic interactions of metazoans with microbial symbionts. Thaumarchaeota are commonly found in sponges, but their potential adaptations to a host-associated lifestyle are largely unknown. Here, we present three novel sponge-associated thaumarchaeal species and compare their genomic and predicted functional features with those of closely related free-living counterparts. We found different degrees of specialization of these thaumarchaeal species to the sponge environment that is reflected in their host distribution and their predicted molecular and metabolic properties. Our results indicate that Thaumarchaeota may have reached different stages of evolutionary adaptation in their symbiosis with sponges.

RevDate: 2019-08-14

Gorman R (2019)

What's in it for the animals? Symbiotically considering 'therapeutic' human-animal relations within spaces and practices of care farming.

Medical humanities pii:medhum-2018-011627 [Epub ahead of print].

Human-animal relations are increasingly imbricated, encountered and experienced in the production of medicine and health. Drawing on an empirical study of care farms in the UK, this article uses the language of symbiosis to develop a framework for critically considering the relationships enrolled within interspecies therapeutic practices. Care farming is an emerging paradigm that aims to deploy farming practices as a form of therapeutic intervention, with human-animal relations framed as providing important opportunities for human health. This article moves to attend to multispecies therapeutic interventions and relationships from a more-than-human perspective, drawing attention to the often-troubling anthropocentrism in which such practices are framed and performed. Attempting to perform and realise human imaginations of 'therapeutic' affects, spaces and relationships can rely on processes that reduce animals' own opportunities for flourishing. Yet, the therapeutic use of other species does not have to be forever anthropocentric or utilitarian. The article explores whether relations between humans and animals might result in a level of mutual proliferation of affective capacities, reciprocally beneficial. These human-animal entanglements highlight opportunities to think more critically about how to practice interspecies relationships and practices in ways that are less parasitic, and instead framed more by attempts at producing opportunities for mutualistic flourishing.

RevDate: 2019-08-14

Dalit M, Keren ML, Eviatar W, et al (2019)

The Algal Symbiont Modifies the Transcriptome of the Scleractinian Coral Euphyllia paradivisa During Heat Stress.

Microorganisms, 7(8): pii:microorganisms7080256.

The profound mutualistic symbiosis between corals and their endosymbiotic counterparts, Symbiodiniaceae algae, has been threatened by the increase in seawater temperatures, leading to breakdown of the symbiotic relationship-coral bleaching. To characterize the heat-stress response of the holobiont, we generated vital apo-symbiotic Euphylliaparadivisa corals that lacked the endosymbiotic algae. Using RNA sequencing, we analyzed the gene expression of these apo-symbionts vs. symbiotic ones, to test the effect of the algal presence on the tolerance of the coral. We utilized literature-derived lists of "symbiosis differentially expressed genes" and "coral heat-stress genes" in order to compare between the treatments. The symbiotic and apo-symbiotic samples were segregated into two separate groups with several different enriched gene ontologies. Our findings suggest that the presence of endosymbionts has a greater negative impact on the host than the environmental temperature conditions experienced by the holobiont. The peak of the stress reaction was identified as 28 °C, with the highest number of differentially expressed genes. We suggest that the algal symbionts increase coral holobiont susceptibility to elevated temperatures. Currently, we can only speculate whether coral species, such as E.paradivisa, with the plasticity to also flourish as apo-symbionts, may have a greater chance to withstand the upcoming global climate change challenge.

RevDate: 2019-08-14

Forester NT, Lane GA, McKenzie CM, et al (2019)

The Role of SreA-Mediated Iron Regulation in Maintaining Epichloë festucae-Lolium perenne Symbioses.

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

In ascomycetes and basidiomycetes, iron-responsive GATA-type transcriptional repressors are involved in regulating iron homeostasis, notably to prevent iron toxicity through control of iron uptake. To date, it has been unknown whether this iron regulator contributes toward mutualistic endosymbiosis of microbes with plants, a system where the endophyte must function within the constraints of an in-host existence, including a dependency on the host for nutrient acquisition. Functional characterization of one such protein, SreA from Epichloë festucae, a fungal endosymbiont of cool-season grasses, indicates that regulation of iron homeostasis processes is important for symbiotic maintenance. The deletion of the sreA gene (ΔsreA) led to iron-dependent aberrant hyphal growth and the gradual loss of endophyte hyphae from perennial ryegrass. SreA negatively regulates the siderophore biosynthesis and high-affinity iron uptake systems of E. festucae, similar to other fungi, resulting in iron accumulation in mutants. Our evidence suggests that SreA is involved in the processes that moderate Epichloë iron acquisition from the plant apoplast, because overharvesting of iron in ΔsreA mutants was detected as premature chlorosis of the host using a hydroponic plant growth assay. E. festucae appears to have a tightly regulated iron management system, involving SreA that balances endophyte growth with its survival and prevents overcompetition with the host for iron in the intercellular niche, thus promoting mutualistic associations. Mutations that interfere with Epichloë iron management negatively affect iron-dependent fungal growth and destabilize mutualistic Epichloë -ryegrass associations.

RevDate: 2019-08-14
CmpDate: 2019-08-14

Yang T, Tedersoo L, Soltis PS, et al (2019)

Phylogenetic imprint of woody plants on the soil mycobiome in natural mountain forests of eastern China.

The ISME journal, 13(3):686-697.

Recent studies have detected strong phylogenetic signals in tree-fungus associations for diseased leaves and mycorrhizal symbioses. However, the extent of plant phylogenetic constraints on the free-living soil mycobiome remains unknown, especially at broad geographic scales. Here, 343 soil samples were collected adjacent to individual tree trunks, representing 58 woody plant species located in five mountain forests of eastern China. Integrating plant species identity and phylogenetic information, we aimed to unravel the relative contributions of phylogenetic relationships among tree species, abiotic environmental filtering, and geographic isolation to the geographic distribution of soil mycobiome. We found that the community dissimilarities of total fungi and each dominant guild (viz. saprotrophs, plant pathogens, and ectomycorrhizal fungi) significantly increased with increasing plant phylogenetic distance. Plant phylogenetic eigenvectors explained 11.4% of the variation in community composition, whereas environmental and spatial factors explained 24.1% and 7.2% of the variation, respectively. The communities of ectomycorrhizal fungi and plant pathogens were relatively more strongly affected by plant phylogeny than those of saprotrophs (13.7% and 10.4% vs. 8.5%). Overall, our results demonstrate how plant phylogeny, environment, and geographic space contribute to forest soil fungal distributions and suggest that the influence of plant phylogeny on fungal association may differ by guilds.

RevDate: 2019-08-14
CmpDate: 2019-08-14

Kudo R, Masuya H, Endoh R, et al (2019)

Gut bacterial and fungal communities in ground-dwelling beetles are associated with host food habit and habitat.

The ISME journal, 13(3):676-685.

Beetles (Coleoptera) have the highest species diversity among all orders, and they have diverse food habits. Gut microbes may have contributed to this diversification of food habits. Here, we identified the pattern of the relationship between ground-dwelling beetles and their gut microbial communities (bacteria and fungi) in the field. We collected 46 beetle species of five families from secondary deciduous forests and grasslands in Japan and extracted microbial DNA from whole guts for amplicon sequencing. The gut bacterial and fungal communities differed among all habitats and all food habits of their hosts (carnivores, herbivores, omnivores, and scavengers) except for the fungal communities between carnivores and scavengers. Specifically, the abundant bacterial group varied among food habits: Xanthomonadaceae were abundant in scavengers, whereas Enterobacteriaceae were abundant in carnivores and herbivores. Phylogenetically closely related beetles had phylogenetically similar communities of Enterobacteriaceae, suggesting that the community structure of this family is related to the evolutionary change in beetle ecology. One of the fungal groups, Yarrowia species, which has been reported to have a symbiotic relationship with silphid beetles, was also detected from various carnivorous beetles. Our results suggest that the symbiotic relationships between ground-dwelling beetles and these microbes are widespread.

RevDate: 2019-08-13

Mestre A, Poulin R, Holt RD, et al (2019)

The interplay of nested biotic interactions and the abiotic environment regulates populations of a hypersymbiont.

The Journal of animal ecology [Epub ahead of print].

1.The role of biotic interactions in shaping the distribution and abundance of species should be particularly pronounced in symbionts. Indeed, symbionts have a dual niche composed of traits of their individual hosts and the abiotic environment external to the host, and often combine active dispersal at finer scales with host-mediated dispersal at broader scales. The biotic complexity in the determinants of species distribution and abundance should be even more pronounced for hypersymbionts (symbionts of other symbionts). 2.We use a chain of symbiosis to explore the relative influence of nested biotic interactions and the abiotic environment on occupancy and abundance of a hypersymbiont. 3.Our empirical system is the epibiont ciliate Lagenophrys discoidea, which attaches to an ostracod that is itself ectosymbiotic on crayfish (the basal host). We applied multimodel selection and variance partitioning for GLMM to assess the relative importance of: 1) traits of symbiotic hosts (ostracod sex and abundance), 2) traits of basal hosts (crayfish body weight, abundance and intermoult stage), 3) the abiotic environment (water chemistry and climate), and 4) geospatial autocorrelation patterns (capturing potential effects of crayfish dispersal among localities). 4.Our models explained about half of the variation in prevalence and abundance of the hypersymbiont. Variation in prevalence was partly explained, in decreasing order of importance (18-4%) by shared effects of symbiotic host traits and the abiotic environment, pure fixed effects of symbiotic hosts, abiotic environment and geospatial patterns (traits of basal hosts were not relevant). Hypersymbiont abundance was most strongly explained by random effects of host traits (mainly the symbiotic host), in addition to weaker fixed effects (mostly abiotic environment). 5.Our results highlight the major role of the interplay between abundance of symbiotic hosts and water physico-chemistry in regulating populations of a hypersymbiotic ciliate, which is likely critical for dispersal dynamics, availability of attachment resources and suitability of on-host living conditions for the ciliate. We also found moderate signal of regulation by the basal host, for which we propose three mechanisms: 1) modulation of microhabitat suitability (crayfish-created water currents); 2) concentration of symbiotic hosts within crayfish; and 3) dispersal mediated by crayfish. This article is protected by copyright. All rights reserved.

RevDate: 2019-08-13

Bockoven AA, Bondy EC, Flores MJ, et al (2019)

What Goes Up Might Come Down: the Spectacular Spread of an Endosymbiont Is Followed by Its Decline a Decade Later.

Microbial ecology pii:10.1007/s00248-019-01417-4 [Epub ahead of print].

Facultative, intracellular bacterial symbionts of arthropods may dramatically affect host biology and reproduction. The length of these symbiont-host associations may be thousands to millions of years, and while symbiont loss is predicted, there have been very few observations of a decline of symbiont infection rates. In a population of the sweet potato whitefly species (Bemisia tabaci MEAM1) in Arizona, USA, we documented the frequency decline of a strain of Rickettsia in the Rickettsia bellii clade from near-fixation in 2011 to 36% of whiteflies infected in 2017. In previous studies, Rickettsia had been shown to increase from 1 to 97% from 2000 to 2006 and remained at high frequency for at least five years. At that time, Rickettsia infection was associated with both fitness benefits and female bias. In the current study, we established matrilines of whiteflies from the field (2016, Rickettsia infection frequency = 58%) and studied (a) Rickettsia vertical transmission, (b) fitness and sex ratios associated with Rickettsia infection, (c) symbiont titer, and (d) bacterial communities within whiteflies. The vertical transmission rate was high, approximately 98%. Rickettsia infection in the matrilines was not associated with fitness benefits or sex ratio bias and appeared to be slightly costly, as more Rickettsia-infected individuals produced non-hatching eggs. Overall, the titer of Rickettsia in the matrilines was lower in 2016 than in the whiteflies collected in 2011, but the titer distribution appeared bimodal, with high- and low-titer lines, and constancy of the average titer within lines over three generations. We found neither association between Rickettsia titer and fitness benefits or sex ratio bias nor evidence that Rickettsia was replaced by another secondary symbiont. The change in the interaction between symbiont and host in 2016 whiteflies may explain the drop in symbiont frequency we observed.

RevDate: 2019-08-13

Cecchi G, Di Piazza S, Marescotti P, et al (2019)

Evidence of pyrite dissolution by Telephora terrestris Ehrh in the Libiola mine (Sestri Levante, Liguria, Italy).

Heliyon, 5(8):e02210 pii:e02210.

Evidence of pyrite dissolution by Telephora terrestris Ehrh were observed for the first time in the abandoned sulphide Libiola mine in May 2017 (Sestri Levante, Liguria, Italy). This fungus is an ectomycorrhizal species able to colonize this extreme environment and bioaccumulate metals such as copper and silver in its fruiting bodies, and it is known to establish symbiosis with maritime pines present in the area, thus favouring their recolonization of the site. This paper presents evidence of T. terrestris promoted dissolution of sulphide minerals. This species can remove from soil not only metals possibly toxic to the pine trees, but it can also contribute to the ions bioaccumulation through the bioweathering of sulphide mineral grains (especially pyrite).

RevDate: 2019-08-13

Dang X, Xie Z, Liu W, et al (2019)

The genome of Ensifer alkalisoli YIC4027 provides insights for host specificity and environmental adaptations.

BMC genomics, 20(1):643 pii:10.1186/s12864-019-6004-7.

BACKGROUND: Ensifer alkalisoli YIC4027, a recently characterized nitrogen-fixing bacterium of the genus Ensifer, has been isolated from root nodules of the host plant Sesbania cannabina. This plant is widely used as green manure and for soil remediation. E. alkalisoli YIC4027 can grow in saline-alkaline soils and is a narrow-host-range strain that establishes a symbiotic relationship with S. cannabina. The complete genome of this strain was sequenced to better understand the genetic basis of host specificity and adaptation to saline-alkaline soils.

RESULTS: E. alkalisoli YIC4027 was found to possess a 6.1-Mb genome consisting of three circular replicons: one chromosome (3.7 Mb), a chromid (1.9 Mb) and a plasmid (0.46 Mb). Genome comparisons showed that strain YIC4027 is phylogenetically related to broad-host-range Ensifer fredii strains. Synteny analysis revealed a strong collinearity between chromosomes of E. alkalisoli YIC4027 and those of the E. fredii NGR234 (3.9 Mb), HH103 (4.3 Mb) and USDA257 (6.48 Mb) strains. Notable differences were found for genes required for biosynthesis of nodulation factors and protein secretion systems, suggesting a role of these genes in host-specific nodulation. In addition, the genome analysis led to the identification of YIC4027 genes that are presumably related to adaptation to saline-alkaline soils, rhizosphere colonization and nodulation competitiveness. Analysis of chemotaxis cluster genes and nodulation tests with constructed che gene mutants indicated a role of chemotaxis and flagella-mediated motility in the symbiotic association between YIC4027 and S. cannabina.

CONCLUSIONS: This study provides a basis for a better understanding of host specific nodulation and of adaptation to a saline-alkaline rhizosphere. This information offers the perspective to prepare optimal E. alkalisoli inocula for agriculture use and soil remediation.

RevDate: 2019-08-13

Miura C, Saisho M, Yagame T, et al (2019)

Bletilla striata (Orchidaceae) Seed Coat Restricts the Invasion of Fungal Hyphae at the Initial Stage of Fungal Colonization.

Plants (Basel, Switzerland), 8(8): pii:plants8080280.

Orchids produce minute seeds that contain limited or no endosperm, and they must form an association with symbiotic fungi to obtain nutrients during germination and subsequent seedling growth under natural conditions. Orchids need to select an appropriate fungus among diverse soil fungi at the germination stage. However, there is limited understanding of the process by which orchids recruit fungal associates and initiate the symbiotic interaction. This study aimed to better understand this process by focusing on the seed coat, the first point of fungal attachment. Bletilla striata seeds, some with the seed coat removed, were prepared and sown with symbiotic fungi or with pathogenic fungi. The seed coat-stripped seeds inoculated with the symbiotic fungi showed a lower germination rate than the intact seeds, and proliferated fungal hyphae were observed inside and around the stripped seeds. Inoculation with the pathogenic fungi increased the infection rate in the seed coat-stripped seeds. The pathogenic fungal hyphae were arrested at the suspensor side of the intact seeds, whereas the seed coat-stripped seeds were subjected to severe infestation. These results suggest that the seed coat restricts the invasion of fungal hyphae and protects the embryo against the attack of non-symbiotic fungi.

RevDate: 2019-08-12

Wilker J, Navabi A, Rajcan I, et al (2019)

Agronomic Performance and Nitrogen Fixation of Heirloom and Conventional Dry Bean Varieties Under Low-Nitrogen Field Conditions.

Frontiers in plant science, 10:952.

Common beans (Phaseolus vulgaris) form a relationship with nitrogen-fixing rhizobia and through a process termed symbiotic nitrogen fixation (SNF) which provides them with a source of nitrogen. However, beans are considered poor nitrogen fixers, and modern production practices involve routine use of N fertilizer, which leads to the down-regulation of SNF. High-yielding, conventionally bred bean varieties are developed using conventional production practices and selection criteria, typically not including SNF efficiency, and may have lost this trait over decades of modern breeding. In contrast, heirloom bean genotypes were developed before the advent of modern production practices and may represent an underutilized pool of genetics which could be used to improve SNF. This study compared the SNF capacity under low-N field conditions, of collections of heirloom varieties with and conventionally bred dry bean varieties. The heirloom-conventional panel (HCP) consisted of 42 genotypes from various online seed retailers or from the University of Guelph Bean Breeding program seedbank. The HCP was genotyped using a single nucleotide polymorphism (SNP) array to investigate genetic relatedness within the panel. Field trials were conducted at three locations in ON, Canada from 2014 to 2015 and various agronomic and seed composition traits were measured, including capacity for nitrogen fixation (using the natural abundance method to measure seed N isotope ratios). Significant variation for SNF was found in the panel. However, on average, heirloom genotypes did not fix significantly more nitrogen than conventionally bred varieties. However, five heirloom genotypes fixed >60% of their nitrogen from the atmosphere. Yield (kg ha-1) was not significantly different between heirloom and conventional genotypes, suggesting that incorporating heirloom genotypes into a modern breeding program would not negatively impact yield. Nitrogen fixation was significantly higher among Middle American genotypes than among Andean genotypes, confirming previous findings. The best nitrogen fixing line was Coco Sophie, a European heirloom white bean whose genetic makeup is admixed between the Andean and Middle American genepools. Heirloom genotypes represent a useful source of genetics to improve SNF in modern bean breeding.

RevDate: 2019-08-12
CmpDate: 2019-08-12

Cappelli A, Valzano M, Cecarini V, et al (2019)

Killer yeasts exert anti-plasmodial activities against the malaria parasite Plasmodium berghei in the vector mosquito Anopheles stephensi and in mice.

Parasites & vectors, 12(1):329 pii:10.1186/s13071-019-3587-4.

BACKGROUND: Wickerhamomyces anomalus is a yeast associated with different insects including mosquitoes, where it is proposed to be involved in symbiotic relationships with hosts. Different symbiotic strains of W. anomalus display a killer phenotype mediated by protein toxins with broad-spectrum antimicrobial activities. In particular, a killer toxin purified from a W. anomalus strain (WaF17.12), previously isolated from the malaria vector mosquito Anopheles stephensi, has shown strong in vitro anti-plasmodial activity against early sporogonic stages of the murine malaria parasite Plasmodium berghei.

RESULTS: Here, we provide evidence that WaF17.12 cultures, properly stimulated to induce the expression of the killer toxin, can directly affect in vitro P. berghei early sporogonic stages, causing membrane damage and parasite death. Moreover, we demonstrated by in vivo studies that mosquito dietary supplementation with activated WaF17.12 cells interfere with ookinete development in the midgut of An. stephensi. Besides the anti-sporogonic action of WaF17.12, an inhibitory effect of purified WaF17.12-killer toxin was observed on erythrocytic stages of P. berghei, with a consequent reduction of parasitaemia in mice. The preliminary safety tests on murine cell lines showed no side effects.

CONCLUSIONS: Our findings demonstrate the anti-plasmodial activity of WaF17.12 against different developmental stages of P. berghei. New studies on P. falciparum are needed to evaluate the use of killer yeasts as innovative tools in the symbiotic control of malaria.

RevDate: 2019-08-12
CmpDate: 2019-08-12

Bhat MI, Sowmya K, Kapila S, et al (2019)

Escherichia coli K12: An evolving opportunistic commensal gut microbe distorts barrier integrity in human intestinal cells.

Microbial pathogenesis, 133:103545.

Commensal enteric microbes under specific conditions viz. immunocompromised system, altered microbiota or uncompetitive niche induce their otherwise dormant pathogenic phenotype to distort host cellular functioning. Here we investigate how under in vitro environment established by using Caco-2 cells, commensal gut microbe E. coli K12 (ATCC 14849) disrupt intestinal epithelial barrier function. Caco-2 cells exposed to E. coli showed the time dependent significant (P < 0.01) decrease in transepithelial electrical resistance (TEER) and concomitantly increased phenol red flux across cell monolayer in contrast to non infected control cells. E. coli infected intestinal cells were observed with suppressed (p < 0.05) mRNA levels of ZO-1, Claudin-1, Occludin and Cingulin-1 in contrast to significantly (p < 0.05) higher PIgR and hbd-2 mRNA fold changes. Immunofluorescent and electron micrographs revealed the disrupted distribution and localisation of specific tight junction proteins (Zo-1 and Claudin-1) and actin filament in E. coli infected Caco-2 cells that ultimately resulted in deformed cellular morphology. Taken together, E. coli K12 under compromised in vitro milieu disrupted the intestinal barrier functions by decreasing the expression of important tight junction genes along with the altered distribution of associated proteins that increased the intestinal permeability as reflected by phenol red flux and TEER values.

RevDate: 2019-08-12
CmpDate: 2019-08-12

Salehi M, Moieni A, Safaie N, et al (2019)

New synergistic co-culture of Corylus avellana cells and Epicoccum nigrum for paclitaxel production.

Journal of industrial microbiology & biotechnology, 46(5):613-623.

Paclitaxel is a main impressive chemotherapeutic agent with unique mode of action and broad-spectrum activity against cancers. Hazel (Corylus avellana) is a paclitaxel-producing species through bioprospection. Endophytic fungi have significant roles in plant paclitaxel production. This study evaluated the effect of co-culture of C. avellana cells and paclitaxel-producing endophytic fungus, Epicoccum nigrum strain YEF2 and also the effect of elicitors derived from this fungal strain on paclitaxel production. The results clearly revealed that co-culture of C. avellana cells and E. nigrum was more effective than elicitation of C. avellana cells by only cell extract or culture filtrate of this fungal strain. Co-culture of C. avellana cells and E. nigrum surpassed monocultures in terms of paclitaxel production designating their synergistic interaction potential. Fungal inoculum amount, co-culture establishment time and co-culture period were important factors for achieving the maximum production of paclitaxel in this co-culture system. The highest total yield of paclitaxel (404.5 µg L-1) was produced in co-culture established on 13th day using 3.2% (v/v) of E. nigrum mycelium suspension, which was about 5.5 and 136.6 times that in control cultures of C. avellana cells and E. nigrum, respectively. This is the first report on positive effect of co-culture of paclitaxel-producing endophytic fungus and non-host plant cells for enhancing paclitaxel production.

RevDate: 2019-08-12
CmpDate: 2019-08-12

Cui JH, Dong SM, Chen CX, et al (2019)

Microplitis bicoloratus bracovirus modulates innate immune suppression through the eIF4E-eIF4A axis in the insect Spodoptera litura.

Developmental and comparative immunology, 95:101-107.

Eukaryotic initiation factor 4E (eIF4E) is regulated during the innate immune response. However, its translational regulation under innate immune suppression remains largely unexplored. Microplitis bicoloratus bracovirus (MbBV), a symbiotic virus harbored by the parasitoid wasp, Microplitis bicoloratus, suppresses innate immunity in parasitized Spodoptera litura. Here, we generated eIF4E dsRNA and used it to silence the eIF4E gene of S. litura, resulting in a hallmark immunosuppressive phenotype characterized by increased apoptosis of hemocytes and retardation of head capsule width development. In response to natural parasitism, loss of eIF4E function was associated with similar immunosuppression, and we detected no significant differences between the response to parasitism and treatment with eIF4E RNAi. Under MbBV infection, eIF4E overexpression significantly suppressed MbBV-induced increase in apoptosis and suppressed apoptosis to the same extent as co-expression of both eIF4E and eIF4A. There were no significant differences between MbBV-infected and uninfected larvae in which eIF4E was overexpressed. More importantly, in the eIF4E RNAi strain, eIF4A RNAi did not increase apoptosis. Collectively, our results indicate that eIF4E plays a nodal role in the MbBV-suppressed innate immune response via the eIF4E-eIF4A axis.

RevDate: 2019-08-13
CmpDate: 2019-08-13

Yamashita T, Rhoads DD, J Pummill (2019)

Genome Analyses of a New Mycoplasma Species from the Scorpion Centruroides vittatus.

G3 (Bethesda, Md.), 9(4):993-997 pii:g3.118.200858.

Arthropod Mycoplasma are little known endosymbionts in insects, primarily known as plant disease vectors. Mycoplasma in other arthropods such as arachnids are unknown. We report the first complete Mycoplasma genome sequenced, identified, and annotated from a scorpion, Centruroides vittatus, and designate it as Mycoplasma vittatus We find the genome is at least a 683,827 bp single circular chromosome with a GC content of 42.7% and with 987 protein-coding genes. The putative virulence determinants include 11 genes associated with the virulence operon associated with protein synthesis or DNA transcription and ten genes with antibiotic and toxic compound resistance. Comparative analysis revealed that the M. vittatus genome is smaller than other Mycoplasma genomes and exhibits a higher GC content. Phylogenetic analysis shows M. vittatus as part of the Hominis group of Mycoplasma As arthropod genomes accumulate, further novel Mycoplasma genomes may be identified and characterized.

RevDate: 2019-08-12
CmpDate: 2019-08-12

Guzmán-Guzmán P, Porras-Troncoso MD, Olmedo-Monfil V, et al (2019)

Trichoderma Species: Versatile Plant Symbionts.

Phytopathology, 109(1):6-16.

Because of the need to provide food for the growing population, agricultural activity is faced with the huge challenge of counteracting the negative effects generated by adverse environmental factors and diseases caused by pathogens on crops, while avoiding environmental pollution due to the excessive use of agrochemicals. The exploitation of biological systems that naturally increase plant vigor, preparing them against biotic and abiotic stressors that also promote their growth and productivity represents a useful and viable strategy to help face these challenges. Fungi from the genus Trichoderma have been widely used in agriculture as biocontrol agents because of their mycoparasitic capacity and ability to improve plant health and protection against phytopathogens, which makes it an excellent plant symbiont. The mechanisms employed by Trichoderma include secretion of effector molecules and secondary metabolites that mediate the beneficial interaction of Trichoderma with plants, providing tolerance to biotic and abiotic stresses. Here we discuss the most recent advances in understanding the mechanisms employed by this opportunistic plant symbiont as biocontrol agent and plant growth promoter. In addition, through genome mining we approached a less explored factor that Trichoderma could be using to become successful plant symbionts, the production of phytohormones-auxins, cytokinins, abscisic acid, gibberellins, among others. This approach allowed us to detect sets of genes encoding proteins potentially involved in phytohormone biosynthesis and signaling. We discuss the implications of these findings in the physiology of the fungus and in the establishment of its interaction with plants.

RevDate: 2019-08-13
CmpDate: 2019-08-13

Zhou J, Duan J, Gao M, et al (2019)

Diversity, Roles, and Biotechnological Applications of Symbiotic Microorganisms in the Gut of Termite.

Current microbiology, 76(6):755-761.

Termites are global pests and can cause serious damage to buildings, crops, and plantation forests. The symbiotic intestinal flora plays an important role in the digestion of cellulose and nitrogen in the life of termites. Termites and their symbiotic microbes in the gut form a synergistic system. These organism work together to digest lignocellulose to make the termites grow on nitrogen deficient food. In this paper, the diversity of symbiotic microorganisms in the gut of termites, including protozoan, spirochetes, actinomycetes, fungus and bacteria, and their role in the digestion of lignocellulose and also the biotechnological applications of these symbiotic microorganisms are discussed. The high efficiency lignocellulose degradation systems of symbiotic microbes in termite gut not only provided a new way of biological energy development, but also has immense prospect in the application of cellulase enzymes. In addition, the study on the symbiotic microorganisms in the gut of termites will also provide a new method for the biological control of termites by the endophytic bacteria in the gut of termites.

RevDate: 2019-08-13
CmpDate: 2019-08-13

Hillesland KL (2018)

Evolution on the bright side of life: microorganisms and the evolution of mutualism.

Annals of the New York Academy of Sciences, 1422(1):88-103.

Mutualistic interactions, where two interacting species have a net beneficial effect on each other's fitness, play a crucial role in the survival and evolution of many species. Despite substantial empirical and theoretical work in past decades, the impact of these interactions on natural selection is not fully understood. In addition, mutualisms between microorganisms have been largely ignored, even though they are ecologically important and can be used as tools to bridge the gap between theory and empirical work. Here, I describe two problems with our current understanding of natural selection in mutualism and highlight the properties of microbial mutualisms that could help solve them. One problem is that bias and methodological problems have limited our understanding of the variety of mechanisms by which species may adapt to mutualism. Another problem is that it is rare for experiments testing coevolution in mutualism to address whether each species has adapted to evolutionary changes in its partner. These problems can be addressed with genome resequencing and time-shift experiments, techniques that are easier to perform in microorganisms. In addition, microbial mutualisms may inspire novel insights and hypotheses about natural selection in mutualism.

RevDate: 2019-08-13
CmpDate: 2019-08-13

de Vries J, SB Gould (2018)

The monoplastidic bottleneck in algae and plant evolution.

Journal of cell science, 131(2): pii:jcs.203414.

Plastids in plants and algae evolved from the endosymbiotic integration of a cyanobacterium by a heterotrophic eukaryote. New plastids can only emerge through fission; thus, the synchronization of bacterial division with the cell cycle of the eukaryotic host was vital to the origin of phototrophic eukaryotes. Most of the sampled algae house a single plastid per cell and basal-branching relatives of polyplastidic lineages are all monoplastidic, as are some non-vascular plants during certain stages of their life cycle. In this Review, we discuss recent advances in our understanding of the molecular components necessary for plastid division, including those of the peptidoglycan wall (of which remnants were recently identified in moss), in a wide range of phototrophic eukaryotes. Our comparison of the phenotype of 131 species harbouring plastids of either primary or secondary origin uncovers that one prerequisite for an algae or plant to house multiple plastids per nucleus appears to be the loss of the bacterial genes minD and minE from the plastid genome. The presence of a single plastid whose division is coupled to host cytokinesis was a prerequisite of plastid emergence. An escape from such a monoplastidic bottleneck succeeded rarely and appears to be coupled to the evolution of additional layers of control over plastid division and a complex morphology. The existence of a quality control checkpoint of plastid transmission remains to be demonstrated and is tied to understanding the monoplastidic bottleneck.

RevDate: 2019-08-10

Irshad S, Xie Z, Wang J, et al (2019)

Indigenous strain Bacillus XZM assisted phytoremediation and detoxification of arsenic in Vallisneria denseserrulata.

Journal of hazardous materials, 381:120903 pii:S0304-3894(19)30856-8 [Epub ahead of print].

The symbiosis between Vallisneria denseserrulata and indigenous Bacillus sp. XZM was investigated for arsenic removal for the first time. It was found that the native bacterium was able to reduce arsenic toxicity to the plant by producing higher amount of extra cellular polymeric substances (EPS), indole-3-acetic acid (IAA) and siderosphore. Interestingly, V. denseserrulata-Bacillus sp. XZM partnership showed significantly higher arsenic uptake and removal efficiency. The shift in FT-IR spectra indicated the involvement of amide, carboxyl, hydroxyl and thiol groups in detoxification of arsenic, and the existence of an arsenic metabolizing process in V. denseserrulata leaves. The scanning electron microscopy (SEM) images further confirmed that the bacterium colonized on plant roots and facilitated arsenic uptake by plant under inoculation condition. In plant, most of the arsenic existed as As(III) (85%) and was massively (>77%) found in vacuole of particularly leaves cells. Thus, these findings are highly suggested for arsenic remediation in the constructed wetlands.

RevDate: 2019-08-10

Xiang N, Jiang C, Huang W, et al (2019)

The impact of acute benzo(a)pyrene on antioxidant enzyme and stress-related genes in tropical stony corals (Acropora spp.).

The Science of the total environment, 694:133474 pii:S0048-9697(19)33394-7 [Epub ahead of print].

Coral reefs have extremely high ecological value in tropical and subtropical waters worldwide. However, they have been subjected to the most extensive and prolonged damage in recent decades. Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous hazardous pollutants and are highly resistant to degradation in marine environments. Among these compounds, benzo(a)pyrene (BaP) has exerted pressure on corals due to water discharges, oil spills and coastal tourism. In the present study, the physiological response, oxidative stress and stress-related genetic expressions of two Acropora spp. (Acropora formosa and Acropora nasuta) were analysed. These two coral species were exposed to 10 and 40 μg·L-1 BaP for 24 hand 72 h, respectively. The results show that (1) BaP affects the health of the zooxanthellae in coral symbiosis after BaP exposure for 72 h due to a significant decline in chlorophyll a concentrations in Acropora spp. during this period. (2) An exposure of 10 μg·L-1 BaP for 24 h induced serious oxidative damage to Acropora spp., with a significant decline and increase in superoxide dismutase (SOD) activities in A. formosa and A. nasuta. (3) The P-gp gene is more sensitive in A. formosa, while the Hsp70 gene is more sensitive in A. nasuta. (4) A. formosa showed a lower ability to resist organic pollutants in coral reefs. Overall, further ecotoxicological studies are needed to investigate the impact of chemical pollutants on corals and to compare their different response mechanisms.

RevDate: 2019-08-10

Schwartzman JA, Lynch JB, Flores Ramos S, et al (2019)

Acidic pH promotes lipopolysaccharide modification and alters colonization in a bacteria-animal mutualism.

Molecular microbiology [Epub ahead of print].

Environmental pH can be an important cue for symbiotic bacteria as they colonize their eukaryotic hosts. Using the model mutualism between the marine bacterium Vibrio fischeri and the Hawaiian bobtail squid, we characterized the bacterial transcriptional response to acidic pH experienced during the shift from planktonic to host-associated lifestyles. We found several genes involved in outer membrane structure were differentially expressed based on pH, indicating alterations in membrane physiology as V. fischeri initiates its symbiotic program. Exposure to host-like pH increased the resistance of V. fischeri to the cationic antimicrobial peptide polymixin B, which resembles antibacterial molecules that are produced by the squid to select V. fischeri from the ocean microbiota. Using a forward genetic screen, we identified a homolog of eptA, a predicted phosphoethanolamine transferase, as critical for antimicrobial defense. We used MALDI-MS to verify eptA as an ethanolamine transferase for the lipid-A portion of V. fischeri lipopolysaccharide. We then used a DNA pulldown approach to discover that eptA transcription is activated by the global regulator H-NS. Finally, we revealed that eptA promotes successful squid colonization by V. fischeri, supporting its potential role in initiation of this highly specific symbiosis. This article is protected by copyright. All rights reserved.

RevDate: 2019-08-09

Cohen ML, Mashanova EV, Rosen NM, et al (2019)

Adaptation to temperature stress by Vibrio fischeri facilitates this microbe's symbiosis with the Hawaiian bobtail squid (Euprymna scolopes).

Evolution; international journal of organic evolution [Epub ahead of print].

For microorganisms cycling between free-living and host-associated stages, where reproduction occurs in both of these lifestyles, an interesting inquiry is whether adaptation to stress during the free-living stage can impact microbial fitness in the host. To address this topic, the mutualism between the Hawaiian bobtail squid (Euprymna scolopes) and the marine bioluminescent bacterium Vibrio fischeri was utilized. Using microbial experimental evolution, V. fischeri was selected to low (8°C), high (34°C), and fluctuating temperature stress (8°C/34°C) for 2,000 generations. The temperatures 8°C and 34°C were the lower and upper growth limits, respectively. V. fischeri was also selected to benign temperatures (21°C and 28°C) for 2,000 generations, which served as controls. V. fischeri demonstrated significant adaptation to low, high, and fluctuating temperature stress. V. fischeri did not display significant adaptation to the benign temperatures. Adaptation to stressful temperatures facilitated V. fischeri's ability to colonize the squid host relative to the ancestral lines. Bioluminescence levels also increased. Evolution to benign temperatures did not manifest these results. In summary, microbial adaptation to stress during the free-living stage can promote coevolution between hosts and microorganisms. This article is protected by copyright. All rights reserved.

RevDate: 2019-08-09

Lallemand F, Logacheva M, Le Clainche I, et al (2019)

Thirteen new plastid genomes from mixotrophic and autotrophic species provide insights into heterotrophy evolution in Neottieae orchids.

Genome biology and evolution pii:5545086 [Epub ahead of print].

Mixotrophic species use both organic and mineral carbon sources. Some mixotrophic plants combine photosynthesis and a nutrition called mycoheterotrophy, where carbon is obtained from fungi forming mycorrhizal symbiosis with their roots. These species can lose photosynthetic abilities and evolve full mycoheterotrophy. Besides morphological changes, the latter transition is associated with a deep alteration of the plastid genome. Photosynthesis-related genes are lost first, followed by housekeeping genes, eventually resulting in a highly reduced genome. Whether relaxation of selective constraints already occurs for the plastid genome of mixotrophic species, which remain photosynthetic, is unclear. This is partly due to the difficulty of comparing plastid genomes of autotrophic, mixotrophic and mycoheterotrophic species in a narrow phylogenetic framework. We address this question in the orchid tribe Neottieae, where this large assortment of nutrition types occurs. We sequenced 13 new plastid genomes, including nine mixotrophic species and covering all six Neottieae genera. We investigated selective pressure on plastid genes in each nutrition type and conducted a phylogenetic inference of the group. Surprisingly, photosynthesis-related genes did not experience selection relaxation in mixotrophic species compared to autotrophic relatives. Conversely, we observed evidence for selection intensification for some plastid genes. Photosynthesis is thus still under purifying selection, maybe because of its role in fruit formation and thus reproductive success. Phylogenetic analysis resolved most relationships, but short branches at the base of the tree suggest an evolutionary radiation at the beginning of Neottieae history, which, we hypothesize, may be linked to mixotrophy emergence.

RevDate: 2019-08-09

Weizman E, O Levy (2019)

The role of chromatin dynamics under global warming response in the symbiotic coral model Aiptasia.

Communications biology, 2:282 pii:543.

Extreme weather events frequency and scale are altered due to climate change. Symbiosis between corals and their endosymbiotic-dinoflagellates (Symbiodinium) is susceptible to these events and can lead to what is known as bleaching. However, there is evidence for coral adaptive plasticity in the role of epigenetic that have acclimated to high-temperature environments. We have implemented ATAC-seq and RNA-seq to study the cnidarian-dinoflagellate model Exaptasia pallida (Aiptasia) and expose the role of chromatin-dynamics in response to thermal-stress. We have identified 1309 genomic sites that change their accessibility in response to thermal changes. Moreover, apo-symbiotic Aiptasia accessible sites were enriched with NFAT, ATF4, GATA3, SOX14, and PAX3 motifs and expressed genes related to immunological pathways. Symbiotic Aiptasia accessible sites were enriched with NKx3-1, HNF4A, IRF4 motifs and expressed genes related to oxidative-stress pathways. Our work opens a new path towards understanding thermal-stress gene regulation in association with gene activity and chromatin-dynamics.

RevDate: 2019-08-09

Romero-Munar A, Baraza E, Gulías J, et al (2019)

Arbuscular Mycorrhizal Fungi Confer Salt Tolerance in Giant Reed (Arundo donax L.) Plants Grown Under Low Phosphorus by Reducing Leaf Na+ Concentration and Improving Phosphorus Use Efficiency.

Frontiers in plant science, 10:843.

Salinization is one of the major causes of agricultural soil degradation worldwide. In arid and semi-arid regions with calcareous soils, phosphorus (P) deficiency further worsens the quality of salinized soils. Nonetheless, nutrient poor soils could be suitable of producing second-generation energy crops. Due to its high biomass production, Arundo donax L. (giant reed) is one of the most promising species for energy and second-generation biofuel production. A. donax can be propagated by micropropagation, an in vitro technique that produces high number of homogeneous plantlets. However, crop establishment is often compromised due to poor plantlet acclimatization to the soil environment. Arbuscular mycorrhizal fungi (AM) are components of soil-plant systems able to increase root phosphorus uptake and to confer the plant an increase tolerance to salinity with a consequent enhancement effect of plant growth and yield. In the present study, the relative importance of the early symbiosis establishment between AM fungi and A. donax micropropagated plantlets in the response to salt stress under low phosphorus availability was determined. A commercial inoculum which contained two different AM fungi species: Rhizophagus intraradices and Funneliformis mosseae was used. AM-symbionts (AM) and non-symbionts plants were grown at two phosphorus [2.5 μM (C) and 0.5 mM (P)] and three NaCl (1, 75 and 150 mM) concentrations in a room chamber under controlled conditions. After 5 weeks, AM root colonization was 60, 26 and 15% in 1, 75 and 150 mM NaCl-treated plants, respectively. At 1 and 75 mM NaCl, AM plants showed increased growth. In all saline treatments, AM plants had decreased Na+ uptake, Na+ root-to-shoot translocation, Na+/K+ ratio and increased P and K use efficiencies with respect to C and P plants. AM improved the nutritional status of A. donax plants by enhancing nutrient use efficiency rather than nutrient uptake. Increased phosphorus use efficiency in AM plants could have benefited ion (Na+ and K+) uptake and/or allocation and ultimately ameliorate the plant's response to saline conditions.

RevDate: 2019-08-09

Trappeniers K, Matetovici I, Van Den Abbeele J, et al (2019)

The Tsetse Fly Displays an Attenuated Immune Response to Its Secondary Symbiont, Sodalis glossinidius.

Frontiers in microbiology, 10:1650.

Sodalis glossinidius, a vertically transmitted facultative symbiont of the tsetse fly, is a bacterium in the early/intermediate state of its transition toward symbiosis, representing an important model for investigating how the insect host immune defense response is regulated to allow endosymbionts to establish a chronic infection within their hosts without being eliminated. In this study, we report on the establishment of a tsetse fly line devoid of S. glossinidius only, allowing us to experimentally investigate (i) the complex immunological interactions between a single bacterial species and its host, (ii) how the symbiont population is kept under control, and (iii) the impact of the symbiont on the vector competence of the tsetse fly to transmit the sleeping sickness parasite. Comparative transcriptome analysis showed no difference in the expression of genes involved in innate immune processes between symbiont-harboring (GmmSod+) and S. glossinidius-free (GmmSod-) flies. Re-exposure of (GmmSod-) flies to the endosymbiotic bacterium resulted in a moderate immune response, whereas exposure to pathogenic E. coli or to a close non-insect associated relative of S. glossinidius, i.e., S. praecaptivus, resulted in full immune activation. We also showed that S. glossinidius densities are not affected by experimental activation or suppression of the host immune system, indicating that S. glossinidius is resistant to mounted immune attacks and that the host immune system does not play a major role in controlling S. glossinidius proliferation. Finally, we demonstrate that the absence or presence of S. glossinidius in the tsetse fly does not alter its capacity to mount an immune response to pathogens nor does it affect the fly's susceptibility toward trypanosome infection.

RevDate: 2019-08-09

Cardini U, Bartoli M, Lücker S, et al (2019)

Chemosymbiotic bivalves contribute to the nitrogen budget of seagrass ecosystems.

The ISME journal pii:10.1038/s41396-019-0486-9 [Epub ahead of print].

In many seagrass sediments, lucinid bivalves and their sulfur-oxidizing symbionts are thought to underpin key ecosystem functions, but little is known about their role in nutrient cycles, particularly nitrogen. We used natural stable isotopes, elemental analyses, and stable isotope probing to study the ecological stoichiometry of a lucinid symbiosis in spring and fall. Chemoautotrophy appeared to dominate in fall, when chemoautotrophic carbon fixation rates were up to one order of magnitude higher as compared with the spring, suggesting a flexible nutritional mutualism. In fall, an isotope pool dilution experiment revealed carbon limitation of the symbiosis and ammonium excretion rates up to tenfold higher compared with fluxes reported for nonsymbiotic marine bivalves. These results provide evidence that lucinid bivalves can contribute substantial amounts of ammonium to the ecosystem. Given the preference of seagrasses for this nitrogen source, lucinid bivalves' contribution may boost productivity of these important blue carbon ecosystems.

RevDate: 2019-08-09

Payen VL, Mina E, Van Hée VF, et al (2019)

Monocarboxylate transporters in cancer.

Molecular metabolism pii:S2212-8778(19)30403-X [Epub ahead of print].

BACKGROUND: Tumors are highly plastic metabolic entities composed of cancer and host cells that can adopt different metabolic phenotypes. For energy production, cancer cells may use 4 main fuels that are shuttled in 5 different metabolic pathways. Glucose fuels glycolysis that can be coupled to the tricarboxylic acid (TCA) cycle and oxidative phosphorylation (OXPHOS) in oxidative cancer cells or to lactic fermentation in proliferating and in hypoxic cancer cells. Lipids fuel lipolysis, glutamine fuels glutaminolysis, and lactate fuels the oxidative pathway of lactate, all of which are coupled to the TCA cycle and OXPHOS for energy production. This review focuses on the latter metabolic pathway.

SCOPE OF REVIEW: Lactate, which is prominently produced by glycolytic cells in tumors, was only recently recognized as a major fuel for oxidative cancer cells and as a signaling agent. Its exchanges across membranes are gated by monocarboxylate transporters MCT1-4. This review summarizes the current knowledge about MCT structure, regulation and functions in cancer, with a specific focus on lactate metabolism, lactate-induced angiogenesis and MCT-dependent cancer metastasis. It also describes lactate signaling via cell surface lactate receptor GPR81.

MAJOR CONCLUSIONS: Lactate and MCTs, especially MCT1 and MCT4, are important contributors to tumor aggressiveness. Analyses of MCT-deficient (MCT+/- and MCT-/-) animals and (MCT-mutated) humans indicate that they are druggable, with MCT1 inhibitors being in advanced development phase and MCT4 inhibitors still in the discovery phase. Imaging lactate fluxes non-invasively using a lactate tracer for positron emission tomography would further help to identify responders to the treatments.

RevDate: 2019-08-09
CmpDate: 2019-08-09

Ryszka P, Lichtscheidl I, Tylko G, et al (2019)

Symbiotic microbes of Saxifraga stellaris ssp. alpigena from the copper creek of Schwarzwand (Austrian Alps) enhance plant tolerance to copper.

Chemosphere, 228:183-194.

Saxifraga stellaris var. alpigena grows as one of the very few higher plants in the copper rich area of the "blue creek" in Austria. Two endophytes were isolated from it: Mortierella sp. (fungus), and Stenotrophomonas maltophilia (bacterium). Both microbes were practically inseparable due to resistance of the bacteria to the antibiotics tested. On PDA media, the fungus showed higher tolerance to copper than the bacterium, which disappeared from both the media and the surface of the fungus in the presence of 150 μM of Cu. However, at this Cu concentration, the bacteria were still detectable inside the mycelium and reappeared on the outside when transferred to media of lower Cu concentration. Microscopic studies of in vitro cultivated plants showed that the fungus was present in both, the roots and shoots of the plant. The effects of endophytes on plant performance were assessed in rhizoboxes filled with Cu-rich substratum; plants inoculated with both microbes showed better growth, survival and photosynthesis performance than the non-inoculated controls. The results of this study prove the beneficial influence of the isolated endophytes on the Cu tolerance of S. stellaris, and indicate the ecological potential of applying microbial consortia to plants under extreme environmental conditions.

RevDate: 2019-08-08

Kokkoris V, Hamel C, MM Hart (2019)

Mycorrhizal response in crop versus wild plants.

PloS one, 14(8):e0221037 pii:PONE-D-19-04246.

We proposed a theoretical framework predicting mutualistic outcomes for the arbuscular mycorrhizal (AM) symbiosis based on host provenance (crop versus wild). To test the framework, we grew two isolates of Rhizoglomus irregulare (commercial versus an isolate locally isolated), with five crop plants and five wild plants endemic to the region that co-occur with the locally sourced fungus. While inoculation with either isolate had no effect on plant biomass, it decreased leaf P content, particularly for wild plants. All plants associating with the commercial fungus had lower leaf P. Overall, our data shows that wild plants may be more sensitive to differences in mutualistic quality among fungal isolates.

RevDate: 2019-08-08

Buendia L, Ribeyre C, Bensmihen S, et al (2019)

Brachypodium distachyon tar2lhypo mutant shows reduced root developmental response to symbiotic signal but increased arbuscular mycorrhiza.

Plant signaling & behavior [Epub ahead of print].

Auxin is a major phytohormone that controls root development. A role for auxin is also emerging in the control of plant-microbe interactions, including for the establishment of root endosymbiosis between plants and arbuscular mycorrhizal fungi (AMF). Auxin perception is important both for root colonization by AMF and for arbuscule formation. AMF produce symbiotic signals called lipo-chitooligosaccharides (LCOs) that can modify auxin homeostasis and promote lateral root formation (LRF). Since Brachypodium distachyon (Brachypodium) has a different auxin sensitivity compared to other plant species, we wondered whether this would interfere with the effect of auxin in arbuscular mycorrhizal (AM) symbiosis. Here we tested whether tar2lhypo a Brachypodium mutant with an increase in endogenous auxin content is affected in LRF stimulation by LCOs and in AM symbiosis. We found that, in contrast to control plants, LCO treatment inhibited LRF of the tar2lhypo mutant. However, the level of AMF colonization and the abundance of arbuscules were increased in tar2lhypo compared to control plants, suggesting that auxin also plays a positive role in both AMF colonization and arbuscule formation in Brachypodium.

RevDate: 2019-08-08
CmpDate: 2019-08-08

York A (2017)

Host response: Fungal safeguards in the gut.

Nature reviews. Microbiology, 16(1):1.

RevDate: 2019-08-07

Kavadi SN (2019)

The founding of the Tata Memorial Hospital, 1932-1941.

Indian journal of cancer, 56(3):282-284.

This article presents a brief account of the founding of the Tata Memorial Hospital. It draws upon archival material to show that this was not a mere philanthropic act but a scheme carefully thought-out by the Trustees of the Sir Dorabji Tata Trust. It discusses the major concerns of the Trustees as they deliberated upon establishing the Hospital.

RevDate: 2019-08-07

Lanzoni O, Plotnikov A, Khlopko Y, et al (2019)

The core microbiome of sessile ciliate Stentor coeruleus is not shaped by the environment.

Scientific reports, 9(1):11356 pii:10.1038/s41598-019-47701-8.

Microbiomes of multicellular organisms are one of the hottest topics in microbiology and physiology, while only few studies addressed bacterial communities associated with protists. Protists are widespread in all environments and can be colonized by plethora of different bacteria, including also human pathogens. The aim of this study was to characterize the prokaryotic community associated with the sessile ciliate Stentor coeruleus. 16S rRNA gene metabarcoding was performed on single cells of S. coeruleus and on their environment, water from the sewage stream. Our results showed that the prokaryotic community composition differed significantly between Stentor cells and their environment. The core microbiome common for all ciliate specimens analyzed could be defined, and it was composed mainly by representatives of bacterial genera which include also potential human pathogens and commensals, such as Neisseria, Streptococcus, Capnocytophaga, Porphyromonas. Numerous 16S rRNA gene contigs belonged to endosymbiont "Candidatus Megaira polyxenophila". Our data suggest that each ciliate cell can be considered as an ecological microniche harboring diverse prokaryotic organisms. Possible benefits for persistence and transmission in nature for bacteria associated with protists are discussed. Our results support the hypothesis that ciliates attract potentially pathogenic bacteria and play the role of natural reservoirs for them.

RevDate: 2019-08-06

David AS, Bell-Dereske LP, Emery SM, et al (2019)

Testing for loss of Epichloë and non-epichloid symbionts under altered rainfall regimes.

American journal of botany [Epub ahead of print].

PREMISE: Microbial symbionts can buffer plant hosts from environmental change. Therefore, understanding how global change factors alter the associations between hosts and their microbial symbionts may improve predictions of future changes in host population dynamics and microbial diversity. Here, we investigated how one global change factor, precipitation, affected the maintenance or loss of symbiotic fungal endophytes in a C3 grass host. Specifically, we examined the distinct responses of Epichloë (vertically transmitted and systemic) and non-epichloid endophytes (typically horizontally transmitted and localized) by considering (1) how precipitation altered associations with Epichloë and non-epichloid endophytic taxa across host ontogeny, and (2) interactive effects of water availability and Epichloë on early seedling life history stages.

METHODS: We manipulated the presence of Epichloë amarillans in American beachgrass (Ammophila breviligulata) in a multiyear field experiment that imposed three precipitation regimes (ambient or ±30% rainfall). In laboratory assays, we investigated the interactive effects of water availability and Epichloë on seed viability and germination.

RESULTS: Reduced precipitation decreased the incidence of Epichloë in leaves in the final sampling period, but had no effect on associations with non-epichloid taxa. Epichloë reduced the incidence of non-epichloid endophytes, including systemic p-endophytes, in seeds. Laboratory assays suggested that association with Epichloë is likely maintained, in part, due to increased seed viability and germination regardless of water availability.

CONCLUSIONS: Our study empirically demonstrates several pathways for plant symbionts to be lost or maintained across host ontogeny and suggests that reductions in precipitation can drive the loss of a plant's microbial symbionts.

RevDate: 2019-08-06

Nobre T (2019)

Symbiosis in Sustainable Agriculture: Can Olive Fruit Fly Bacterial Microbiome Be Useful in Pest Management?.

Microorganisms, 7(8): pii:microorganisms7080238.

The applied importance of symbiosis has been gaining recognition. The relevance of symbiosis has been increasing in agriculture, in developing sustainable practices, including pest management. Insect symbiotic microorganisms' taxonomical and functional diversity is high, and so is the potential of manipulation of these microbial partners in suppressing pest populations. These strategies, which rely on functional organisms inhabiting the insect, are intrinsically less susceptible to external environmental variations and hence likely to overcome some of the challenges posed by climate change. Rates of climate change in the Mediterranean Basin are expected to exceed global trends for most variables, and this warming will also affect olive production and impact the interactions of olives and their main pest, the obligate olive fruit fly (Bactroceraoleae). This work summarizes the current knowledge on olive fly symbiotic bacteria towards the potential development of symbiosis-based strategies for olive fruit fly control. Particular emphasis is given to Candidatus Erwinia dacicola, an obligate, vertically transmitted endosymbiont that allows the insect to cope with the olive-plant produced defensive compound oleuropein, as a most promising target for a symbiosis disruption approach.

RevDate: 2019-08-05

Yoshida K, Sanada-Morimura S, Huang SH, et al (2019)

Influences of two coexisting endosymbionts, CI-inducing Wolbachia and male-killing Spiroplasma, on the performance of their host Laodelphax striatellus (Hemiptera: Delphacidae).

Ecology and evolution, 9(14):8214-8224 pii:ECE35392.

The small brown planthopper Laodelphax striatellus (Hemiptera: Delphacidae) is reported to have the endosymbiont Wolbachia, which shows a strong cytoplasmic incompatibility (CI) between infected males and uninfected females. In the 2000s, female-biased L. striatellus populations were found in Taiwan, and this sex ratio distortion was the result of male-killing induced by the infection of another endosymbiont, Spiroplasma. Spiroplasma infection is considered to negatively affect both L. striatellus and Wolbachia because the male-killing halves the offspring of L. striatellus and hinders the spread of Wolbachia infection via CI. Spiroplasma could have traits that increase the fitness of infected L. striatellus and/or coexisting organisms because the coinfection rates of Wolbachia and Spiroplasma were rather high in some areas. In this study, we investigated the influences of the infection of these two endosymbionts on the development, reproduction, and insecticide resistance of L. striatellus in the laboratory. Our results show that the single-infection state of Spiroplasma had a negative influence on the fertility of L. striatellus, while the double-infection state had no significant influence. At late nymphal and adult stages, the abundance of Spiroplasma was lower in the double-infection state than in the single-infection state. In the double-infection state, the reduction of Spiroplasma density may be caused by competition between the two endosymbionts, and the negative influence of Spiroplasma on the fertility of host may be relieved. The resistance of L. striatellus to four insecticides was compared among different infection states of endosymbionts, but Spiroplasma infection did not contribute to increase insecticide resistance. Because positive influences of Spiroplasma infection were not found in terms of the development, reproduction, and insecticide resistance of L. striatellus, other factors improving the fitness of Spiroplasma-infected L. striatellus may be related to the high frequency of double infection in some L. striatellus populations.

RevDate: 2019-08-05

Bromfield ESP, Cloutier S, Robidas C, et al (2019)

Invasive Galega officinalis (Goat's rue) plants in Canada form a symbiotic association with strains of Neorhizobium galegae sv. officinalis originating from the Old World.

Ecology and evolution, 9(12):6999-7004 pii:ECE35266.

The toxic legume plant, Galega officinalis, is native to the Eastern Mediterranean and Black Sea regions. This legume is considered to be a noxious weed, and its establishment in Canada may have resulted from ornamental planting and/or field trials. In its native range, a highly specific nitrogen-fixing symbiosis with the bacterium, Neorhizobium galegae symbiovar (sv.) officinalis, is required for normal growth. In North America, nothing is known about the bacterial symbionts of G. officinalis. Our purpose was to determine the species and symbiovar identity of symbiotic bacteria associated with invasive plants of G. officinalis at five sites in the province of Ontario, Canada. Sequence analysis of four housekeeping (16S rRNA, atpD, glnII, and recA) and two symbiosis (nodC and nifH) genes showed that all 50 bacterial isolates from root nodules of G. officinalis at the five Canadian sites were identical to strains of N. galegae sv. officinalis originating either from Europe or the Caucasus. Plant tests indicated that soils collected from four Canadian sites without a history of agriculture or presence of G. officinalis were deficient in symbiotic bacteria capable of eliciting nodules on this plant. Collectively our data support the hypothesis of anthropogenic co-introduction of G. officinalis and its specific symbiotic bacterium into Canada from the Old World. Factors that may limit the spread of G. officinalis in new environments are discussed.

RevDate: 2019-08-04

González CT, Saltonstall K, H Fernández-Marín (2019)

Garden microbiomes of Apterostigma dentigerum and Apterostigma pilosum fungus-growing ants (Hymenoptera: Formicidae).

Journal of microbiology (Seoul, Korea) pii:10.1007/s12275-019-8639-0 [Epub ahead of print].

Fungus-growing ants share a complex symbiosis with microbes, including fungal mutualists, antibiotic-producing bacteria, and fungal pathogens. The bacterial communities associated with this symbiosis are poorly understood but likely play important roles in maintaining the health and function of fungal gardens. We studied bacterial communities in gardens of two Apterostigma species, A. dentigerum, and A. pilosum, using next-generation sequencing to evaluate differences between the two ant species, their veiled and no-veiled fungal garden types, and across three collection locations. We also compared different parts of nests to test for homogeneity within nests. Enterobacteriaceae dominated gardens of both species and common OTUs were shared across both species and nest types. However, differences in community diversity were detected between ant species, and in the communities of A. dentigerum veiled and no-veiled nests within sites. Apterostigma pilosum had a higher proportion of Phyllo-bacteriaceae and differed from A. dentigerum in the proportions of members of the order Clostridiales. Within A. dentigerum, nests with veiled and no-veiled fungus gardens had similar taxonomic profiles but differed in the relative abundance of some groups, with veiled gardens having more Rhodospirillaceae and Hyphomicrobiaceae, and no-veiled having more Xanthomonadaceae and certain genera in the Enter-obacteriaceae C. However, bacterial communities in Apterostigma fungal gardens are highly conserved and resemble those of the nests of other attine ants with dominant taxa likely playing a role in biomass degradation and defense. Further work is required to understand and explain how bacterial community composition of fungus-growing nests is maintained.

RevDate: 2019-08-04

Bailey GF, Bilsky AM, Rowland MB, et al (2019)

Characterization and expression of tyrosinase-like genes in the anemone Exaiptasia pallida as a function of health and symbiotic state.

Developmental and comparative immunology pii:S0145-305X(19)30275-7 [Epub ahead of print].

Coral disease is a major threat to reef ecosystems and therefore, understanding the cellular pathways underlying disease progression and resistance is critical to mitigating future outbreaks. This study focused on tyrosinase-like proteins in cnidarians, which contribute to melanin synthesis, an invertebrate innate immune defense. Specifically, characterization and phylogenetic analysis of cnidarian tyrosinases was performed and their role in symbiosis and a "mystery disease" in the anemone Exaiptasia pallida was investigated using qPCR. The results reveal a diversity of tyrosinase-like proteins in cnidarians that separate in two major clades on a phylogenetic tree, suggesting functional divergence. Two E. pallida sequences, Ep_Tyr1 and Ep_Tyr2, were further investigated, and qPCR results revealed no gene expression differences as a function of symbiotic state, but decreased expression in late disease stages. Overall this work provides evidence for the participation of tyrosinases in the cnidarian immune response.

RevDate: 2019-08-03

Sun YW, Li Y, Hu Y, et al (2019)

Coordinated regulation of size and number of PHB granules by core and accessory phasins in the facultative microsymbiont Sinorhizobium fredii NGR234.

Applied and environmental microbiology pii:AEM.00717-19 [Epub ahead of print].

The exact roles of various granule-associated proteins (GAPs) of polyhydroxybutyrate (PHB) are poorly investigated particularly in bacteria associated with plants. Here, four structural GAPs, named as phasins PhaP1-PhaP4, were identified and demonstrated as true phasins colocalized with PHB granules in Sinorhizobium fredii NGR234, a facultative microsymbiont of Vigna unguiculata and many other legumes. The conserved PhaP2 dominated in regulation of granule size under both free-living and symbiotic conditions. PhaP1, another conserved phasin, made a higher contribution than accessory PhaP4 and PhaP3 to PHB biosynthesis at stationary phase. PhaP3, with limited phyletic distribution on the symbiosis plasmid of Sinorhizobium, was more important than PhaP1 in regulating PHB biosynthesis in V. unguiculata nodules. In the test conditions, no significant symbiotic defects were observed for mutants lacking individual or multiple phaP genes. The mutant lacking two PHB synthases showed impaired symbiotic performance while mutations in individual PHB synthases or a PHB depolymerase had no symbiotic defects. This phenomenon is not related to either the number or size of PHB granules in test mutants within nodules. Distinct metabolic profiles and cocktail pools of GAPs of different phaP(s) mutants imply that core and accessory phasins can be differentially involved in regulating other cellular process in the facultative microsymbiont S. fredii NGR234.Importance Polyhydroxybutyrate (PHB) granules are a store of carbon and energy in bacteria and archaea, and play an important role in stress adaptation. Recent studies have highlighted distinct roles of several granule-associated proteins (GAPs) in regulating the size, number and localization of PHB granules in free-living bacteria, though our knowledge on the role of GAPs in bacteria associated with plants is still limited. Here we report distinct roles of core and accessory phasins associated with PHB granules of Sinorhizobium fredii NGR234, a broad host range microsymbiont of diverse legumes. Core phasins PhaP2 and PhaP1 are conserved major phasins in free living cells. PhaP2 and an accessory phasin PhaP3 encoded by an auxiliary gene on the symbiosis plasmid are major phasins in nitrogen fixing bacteroids in cowpea nodules. GAPs and metabolic profiles can vary in different phaP mutants. Contrasting symbiotic performance between mutants lacking PHB synthases, depolymerase or phasins were revealed.

RevDate: 2019-08-02

Zhang W, Yuan J, Cheng T, et al (2019)

Flowering-mediated root-fungus symbiosis loss is related to jasmonate-dependent root soluble sugar deprivation.

Plant, cell & environment [Epub ahead of print].

The role of flowering in root-fungal symbiosis is not well understood. Because flowering and fungal symbionts are supported by carbohydrates, we hypothesized that flowering modulates root-beneficial fungal associations through alterations in carbohydrate metabolism and transport. We monitored fungal colonization and soluble sugars in the roots of Arabidopsis thaliana following inoculation with a mutualistic fungus Phomopsis liquidambari across different plant developmental stages. Jasmonate signaling of wild-type plants, sugar transport and root invertase of wild-type and jasmonate-insensitive plants were exploited to assess whether and how jasmonate-dependent sugar dynamics are involved in flowering-mediated fungal colonization alterations. We found that flowering restricts root fungal colonization and activates root jasmonate signaling upon fungal inoculation. Jasmonates reduce the constitutive and fungus-induced accumulation of root glucose and fructose at the flowering stage. Further experiments with sugar transport and metabolism mutant lines revealed that root glucose and fructose positively influence fungal colonization. Diurnal, jasmonate-dependent inhibitions of sugar transport and soluble invertase activity were identified as likely mechanisms for flowering-mediated root sugar depletion upon fungal inoculation. Collectively, our results reveal that flowering drives root-fungus cooperation loss, which is related to jasmonate-dependent root soluble sugar depletion. Limiting the spread of root fungal colonization may direct more resources to flower development.

RevDate: 2019-08-04

McElwain A, Warren MB, Pereira FB, et al (2019)

Pathobiology and first report of larval nematodes (Ascaridomorpha sp.) infecting freshwater mussels (Villosa nebulosa, Unionidae), including an inventory of nematode infections in freshwater and marine bivalves.

International journal for parasitology. Parasites and wildlife, 10:41-58 pii:S2213-2244(19)30067-7.

Little information is available on host-parasite relationships between bivalves and larval nematodes. Herein, we describe nematode larvae (likely stage 2) in the infraorder Ascaridomorpha infecting the foot, intestine, and mantle of a freshwater mussel (Alabama rainbow, Villosa nebulosa [Conrad, 1834]) and detail histopathological changes to infected tissues. A total of 43 live mussels from the South Fork of Terrapin Creek, Alabama, were collected between 2010 and 2014, with 14 sectioned for histopathology and 29 dissected. Of the 14 sectioned mussels, 5 appeared to be uninfected, and 7, 1, and 1 had histozoic infections observed in the foot and intestine, intestine only, and mantle edge and foot, respectively. Twenty-three of 29 (79%) of the mussels dissected were infected by live nematodes, and mean nematode abundance was 8.3 (CL = 5.23-13), with 2 mussels infected with >100 nematodes each. Thus, with a total of 32 of the 43 collected mussels observed with nematodes, overall infection prevalence was 74.4% (CL = 0.594-0.855). The 18S rDNA of this nematode was 99% similar to that of several ascaridids (species of Kathlaniidae Lane, 1914 and Quimperiidae Baylis, 1930) that mature in aquatic/semi-aquatic vertebrates; the recovered 18S phylogenetic tree indicated this nematode from V. nebulosa shares a recent common ancestor with Ichthyobronema hamulatum (Ascaridomorpha: Quimperiidae; GenBank Accession Number KY476351). Pathological changes to tissue associated with these infections comprised focal tissue damage, but a cellular response was not evident. The Alabama rainbow possibly represents an intermediate or paratenic host. Given these results, the nematode is likely not pathogenic under normal stream conditions; however, high intensity infections in the foot could inhibit pedal extension and retraction; which would have demonstrable health consequences to a freshwater mussel. Based on our review of the bivalve mollusc parasite literature, a collective biodiversity of 61 nematodes reportedly exhibit some degree of symbiosis (from commensal to parasitic) with 21 bivalves (28 nematode spp. from 17 marine bivalve spp.; 33 nematode spp. from 4 freshwater bivalve spp.); only four records exist of putatively parasitic nematodes from Unionida. The present study represents the first description of a nematode species that invades the tissues of a Unionidae species.

RevDate: 2019-08-02

Ullah I, Magdy M, Wang L, et al (2019)

Genome-wide identification and evolutionary analysis of TGA transcription factors in soybean.

Scientific reports, 9(1):11186 pii:10.1038/s41598-019-47316-z.

The gain of function in genes and gene families is a continuous process and is a key factor in understanding gene and genome evolution in plants. TGACG-Binding (TGA) transcription factors (TFs) have long been known for their essential roles in plant defence in Arabidopsis, but their roles in legume symbiosis are yet to be explored. Here, we identified a total of 25 TGA (named GmTGA1-GmTGA25) genes in soybean. Through phylogenetic analysis, we discovered a clade of GmTGA proteins that appear to be legume-specific. Among them, two GmTGAs were unique by possessing the autophagy sequence in their proteins, while the third one was an orphan gene in soybean. GmTGAs were structurally different from AtTGAs, and their expression patterns also differed with the dominant expression of AtTGAs and GmTGAs in aerial and underground parts, respectively. Moreover, twenty-five GmTGAs showed a strong correlation among the gene expression in roots, nodules, and root hairs. The qRT-PCR analysis results revealed that among 15 tested GmTGAs, six were induced and four were suppressed by rhizobia inoculation, while 11 of these GmTGAs were induced by high nitrate. Our findings suggested the important roles of GmTGAs in symbiotic nodulation and in response to nitrogen availability in soybean.

RevDate: 2019-08-01

Pereira J, Simões M, JL Silva (2019)

Microalgal assimilation of vitamin B12 toward the production of a superfood.

Journal of food biochemistry, 43(8):e12911.

A network of components from different metabolic pathways is the building scaffold of an indispensable compound in the human organism-vitamin B12 . The biosynthesis of this compound is restricted to a limited number of representatives of bacteria and archaea, while vitamin B12 -dependent enzymes are spread through several domains of life. Different attempts have been performed to increase vitamin B12 levels in dietary products, particularly in vegetarian and vegan dietary regimes. The integration of vitamin B12 in microalgae through symbiosis with microorganisms generally recognized as safe, for example the probiotic Lactobacillus reuteri, can even increase the nutritional value of the microalgal biomass. This study reviews the microbial production of vitamin B12 based on genetic analyses and chemical studies. Recent genetic approaches are focused, particularly potential metabolic engineering targets to increase vitamin B12 production. The bioincorporation of vitamin B12 in microalgae as an attempt to provide a superfood is also reviewed. PRACTICAL APPLICATIONS: Novel food habits (i.e., vegan lifestyle) may lack relevant nutrients, including vitamin B12 . Therefore, there is an increased demand for dietary products rich in vitamin B12 . Of potential interest is the provision of microbial-based superfood rich in numerous nutrients, including this vitamin. This manuscript provides an in-depth and timely overview on vitamin B12 biosynthesis and the major advances on metabolic engineering for improved vitamin B12 production by probiotic bacteria and other microorganisms generally recognized as safe. A relevant advance would result from the bioincorporation of vitamin B12 in alternative microorganisms (non-vitamin B12 producers) increasingly recognized as superfood, that is microalgae.

RevDate: 2019-07-30

Kashkouli M, Fathipour Y, M Mehrabadi (2019)

Heritable Gammaproteobacterial Symbiont Improves the Fitness of Brachynema germari Kolenati (Hemiptera: Pentatomidae).

Environmental entomology pii:5540652 [Epub ahead of print].

The pistachio green stink bug, Brachynema germari Kolenati, is an abundant and economic insect pest in most pistachio-growing regions. Some physiological and ecological features of this pest have been studied, but the microbiological nature of symbiotic bacteria and biological aspects of this host-symbiont interaction have been poorly understood. In the present study, we explored the host-associated environment, phylogeny, and acquisition features of the bacterial symbiont of the insect. Furthermore, the importance of the symbiont on the biological (i.e., lifespan, stage composition, and body weight) and behavioral characteristics (i.e., resting/wandering behaviors of the newborn nymphs) of the host were investigated. We found that a rod-shaped gammaproteobacterium was persistently colonized the fourth midgut region of the insect. Molecular phylogenetic and fluorescence in situ hybridization analyses strongly suggest that this symbiont should be placed in the genus Pantoea of the Enterobacteriales. Egg surface sterilization resulted in the aposymbiotic insects suggesting the vertical transmission of symbiont via egg surface smearing upon oviposition. Symbiotic and aposymbiotic B. germari showed no significant differences in the wandering behaviors of the first nymphal stages, whereas the symbiont-free insects exhibited retarded growth, lower longevity, and adult body weight. Taken together, these data provide a better understanding of the relationship between the bacterial symbiont and B. germari and demonstrate that the insect is heavily affected by the deprival of its gut symbionts.

RevDate: 2019-08-02

Li X, He XL, Zhou Y, et al (2019)

Effects of Dark Septate Endophytes on the Performance of Hedysarum scoparium Under Water Deficit Stress.

Frontiers in plant science, 10:903.

Hedysarum scoparium, a species characterized by rapid growth and high drought resistance, has been used widely for vegetative restoration of arid regions in Northwest China that are prone to desertification. Desert soil is typically deficient in available water and the alleviation of drought stress to host plants by endophytes could be an efficient strategy to increase the success of desert restoration. With the objective to seek more beneficial symbionts that can be used in the revegetation strategies, we addressed the question whether H. scoparium can benefit from inoculation by dark septate endophytes (DSEs) isolated from other desert plants. We investigated the influences of four non-host DSE strains (Phialophora sp., Knufia sp., Leptosphaeria sp., and Embellisia chlamydospora) isolated from other desert plants on the performance of H. scoparium under different soil water conditions. Differences in plant performance, such as plant growth, antioxidant enzyme activities, carbon, nitrogen, and phosphorous concentration under all the treatments, were examined. Four DSE strains could colonize the roots of H. scoparium successfully, and they established a positive symbiosis with the host plants depending on DSE species and water availability. The greatest benefits of DSE inoculation occurred in water stress treatment. Specifically, Phialophora sp. and Leptosphaeria sp. improved the root biomass, total biomass, nutrient concentration, and antioxidant enzyme activities of host plants under water deficit conditions. These data contribute to the understanding of the ecological function of DSE fungi in drylands.

RevDate: 2019-08-02

Wilkinson TDJ, Miranda JP, Ferrari J, et al (2019)

Aphids Influence Soil Fungal Communities in Conventional Agricultural Systems.

Frontiers in plant science, 10:895.

Arbuscular mycorrhizal fungi (AMF) form symbioses with the roots of most plant species, including cereals. AMF can increase the uptake of nutrients including nitrogen (N) and phosphorus (P), and of silicon (Si) as well as increase host resistance to various stresses. Plants can simultaneously interact with above-ground insect herbivores such as aphids, which can alter the proportion of plant roots colonized by AMF. However, it is unknown if aphids impact the structure of AMF communities colonizing plants or the extent of the extraradical mycelium produced in the soil, both of which can influence the defensive and nutritional benefit a plant derives from the symbiosis. This study investigated the effect of aphids on the plant-AMF interaction in a conventionally managed agricultural system. As plants also interact with other soil fungi, the non-AMF fungal community was also investigated. We hypothesized that aphids would depress plant growth, and reduce intraradical AMF colonization, soil fungal hyphal density and the diversity of AM and non-AM fungal communities. To test the effects of aphids, field plots of barley enclosed with insect proof cages were inoculated with Sitobion avenae or remained uninoculated. AMF specific and total fungal amplicon sequencing assessed root fungal communities 46 days after aphid addition. Aphids did not impact above-ground plant biomass, but did increase the grain N:P ratio. Whilst aphid presence had no impact on AMF intraradical colonization, soil fungal hyphal length density, or AMF community characteristics, there was a trend for the aphid treatment to increase vesicle numbers and the relative abundance of the AMF family Gigasporaceae. Contrary to expectations, the aphid treatment also increased the evenness of the total fungal community. This suggests that aphids can influence soil communities in conventional arable systems, a result that could have implications for multitrophic feedback loops between crop pests and soil organisms across the above-below-ground interface.

RevDate: 2019-08-08

Xu H, Shao H, Y Lu (2019)

Arbuscular mycorrhiza fungi and related soil microbial activity drive carbon mineralization in the maize rhizosphere.

Ecotoxicology and environmental safety, 182:109476.

This research is aimed to investigate the effect of arbuscular mycorrhiza (AM) fungi on soil microbial activity and carbon mineralization in the maize rhizosphere under potted condition. Glomus etunicatum was used for our experiment. Results showed that AM symbiosis increased the levels of microorganism in the maize rhizosphere soil, and enhanced activity of soil microbial enzymes. After inoculating AM fungi, the contents of dissolved organic carbon (DOC), microbial biomass carbon (MBC) and readily oxidizable carbon (ROC) in the rhizosphere soil of maize increased with varying degrees. We obtained strong evidence that higher contents of MBC, DOC, ROC, superior number of microbes and stronger soil enzyme activities could be responsible for the higher rate of carbon mineralization in AM fungi treatment. AM fungi inoculation was confirmed to be effective to improve the soil quality for larger-scale ecoengineering.

RevDate: 2019-07-28

Antoniou NA, AA Zorpas (2019)

Quality protocol and procedure development to define end-of-waste criteria for tire pyrolysis oil in the framework of circular economy strategy.

Waste management (New York, N.Y.), 95:161-170.

The requirements to define End-of-Waste Criteria (EWC) were set in the Waste Framework Directive (WFD), Article 6 and the detailed data collected are considered to be the baseline for the elaboration of the operational EWC through several steps. Such waste stream (which is produced from End of Life Tires-ELT) could be a valuable source for energy recovery and can be used on a pan-European basis as an alternative fuel, for co-incineration in cement plants or furthermore in internal compunctions engines. The exploration for sustainable energy is one of the most dynamic areas of research currently. This study aims to investigate the ability to manage and exploit the energy content of Tire Pyrolysis Oil (TPO), through pyrolysis technology as incineration/co-incineration technology for ELTs presents significant environmental issues. However, TPO, must be declassified from waste in order to be able to be use as an alternative fuel in internal combustion engines for power generation participating in the loop of circular economy and industrial symbiosis. This paper focus on the development of a Quality Protocol (QP) and the procedure how to develop EWC for the declassification of TPO in order to replace Light Fuel Oil (LFO).

RevDate: 2019-07-26

Petersen G, Darby H, Lam VKY, et al (2019)

Mycoheterotrophic Epirixanthes (Polygalaceae) has a typical angiosperm mitogenome but unorthodox plastid genomes.

Annals of botany pii:5539072 [Epub ahead of print].

BACKGROUND AND AIMS: Fully mycoheterotrophic plants derive carbon and other nutrients from root-associated fungi and have lost the ability to photosynthesize. While mycoheterotroph plastomes are often degraded compared to green plants, the effect of this unusual symbiosis on mitochondrial genome evolution is unknown. By providing the first complete organelle genome data from Polygalaceae, one of only three eudicot families that developed mycoheterotrophy, we explore how both organellar genomes evolved after photosynthesis loss.

METHODS: We sequenced and assembled four complete plastid genomes and a mitochondrial genome from species of Polygalaceae, focusing on non-photosynthetic Epirixanthes. We compared these genomes to those of other mycoheterotroph and parasitic plant lineages, and assessed whether organelle genes in Epirixanthes experienced relaxed or intensified selection compared to autotrophic relatives.

KEY RESULTS: Plastomes of two species of Epirixanthes have become substantially degraded compared to that of autotrophic Polygala. Although the lack of photosynthesis is presumably homologous in the genus, the surveyed Epirixanthes species have marked differences in terms of plastome size, structural rearrangements, gene content and substitution rates. Remarkably, both apparently replaced a canonical plastid inverted repeat with large directly repeated sequences. The mitogenome of E. elongata incorporated a considerable number of fossilized plastid genes, by intracellular transfer from an ancestor with a less degraded plastome. Both plastid and mitochondrial genes in E. elongata have increased substitution rates, but the plastid genes of E. pallida do not. Despite this, both species have similar selection patterns operating on plastid housekeeping genes.

CONCLUSIONS: Plastome evolution largely fits with patterns of gene degradation seen in other heterotrophic plants, but includes highly unusual directly duplicated regions. The causes of rate elevation in the sequenced Epirixanthes mitogenome and of rate differences in plastomes of related mycoheterotrophic species are not currently understood.

RevDate: 2019-07-26

Rueckert S, Betts EL, AD Tsaousis (2019)

The Symbiotic Spectrum: Where Do the Gregarines Fit?.

Trends in parasitology pii:S1471-4922(19)30164-3 [Epub ahead of print].

Gregarine apicomplexans are closely related to parasites such as Plasmodium, Toxoplasma, and Cryptosporidium, which are causing severe health and economic burdens. Colonizing only invertebrates and having no obvious medical relevance, they are mostly ignored in 'omics' studies, although gregarines are the most basal apicomplexans and therefore key players in the understanding of the evolution of parasitism in the Apicomplexa from free-living ancestors. They belong to the largest exclusively parasitic phylum, but is this perception actually true? The effects of gregarines on their hosts seem to cover the whole spectrum of symbiosis from mutualistic to parasitic. We suggest future research directions to understand the evolutionary role of gregarines, by elucidating their biology and interaction with their hosts and the hosts' microbiota.

RevDate: 2019-07-25

Ogawa W, Takeda Y, Endo N, et al (2019)

Repeated fruiting of Japanese golden chanterelle in pot culture with host seedlings.

Mycorrhiza pii:10.1007/s00572-019-00908-z [Epub ahead of print].

Yellow chanterelles are among the most popular wild edible ectomycorrhizal mushrooms worldwide. The representative European golden chanterelle, Cantharellus cibarius, has only once been reported to fruit under greenhouse conditions, due to the difficulty of establishing pure culture. Recently, we developed a new technique for establishing a pure culture of a Japanese golden chanterelle (Cantharellus anzutake), and conducted in vitro ectomycorrhizal synthesis using established strains and Pinus densiflora. Acclimated pine mycorrhizal seedlings colonized with C. anzutake in a pot system under laboratory conditions produced small but distinct basidiomata with developed basidiospores. C. anzutake mycorrhizae were established on Quercus serrata seedlings by inoculation of mycorrhizal root tips of the fungus synthesized on P. densiflora. A scaled-up C. anzutake-host system in larger pots (4 L soil volume) exhibited repeated fruiting at 20-24 °C under continuous light illumination at 150 μmol m-2 s-1 during a 2-year incubation period. Therefore, a C. anzutake cultivation trial is practical under controlled environmental conditions.

RevDate: 2019-07-26

Bernasconi R, Stat M, Koenders A, et al (2019)

Establishment of Coral-Bacteria Symbioses Reveal Changes in the Core Bacterial Community With Host Ontogeny.

Frontiers in microbiology, 10:1529.

Bacterial communities are fundamental symbionts of corals. However, the process by which bacterial communities are acquired across the life history of corals, particularly in larval and early juvenile stages, is still poorly characterized. Here, transfer of bacteria of the Scleractinian coral Acropora digitifera from adults to spawned egg-sperm bundles was analyzed, as well as acquisition across early developmental stages (larvae and newly settled spat), and 6-month-old juveniles. Larvae were reared under manipulated environmental conditions to determine the source (maternal, seawater, or sediment) of bacteria likely to establish symbiotic relationships with the host using amplicon sequencing of the 16S rRNA gene. Maternal colonies directly transferred bacteria from the families Rhodobacteraceae, Cryomorphaceae, and Endozoicimonaceae to egg-sperm bundles. Furthermore, significant differences in the microbial community structure were identified across generations, yet the structure of the coral bacterial community across early life history stages was not impacted by different environmental rearing conditions. These data indicate that the uptake and structure of bacterial communities is developmentally, rather than environmentally, regulated. Both maternal coral colonies and ubiquitous bacteria found across environmental substrates represent a potential source of symbionts important in establishing the coral microbiome. Uniquely, we report the presence of variation with ontogeny of both the core and resident bacterial communities, supporting the hypothesis that microbial communities are likely to play specific roles within the distinct life history stages of the coral host.

RevDate: 2019-08-07

Feng H, Edwards N, Anderson CMH, et al (2019)

Trading amino acids at the aphid-Buchnera symbiotic interface.

Proceedings of the National Academy of Sciences of the United States of America, 116(32):16003-16011.

Plant sap-feeding insects are widespread, having evolved to occupy diverse environmental niches despite exclusive feeding on an impoverished diet lacking in essential amino acids and vitamins. Success depends exquisitely on their symbiotic relationships with microbial symbionts housed within specialized eukaryotic bacteriocyte cells. Each bacteriocyte is packed with symbionts that are individually surrounded by a host-derived symbiosomal membrane representing the absolute host-symbiont interface. The symbiosomal membrane must be a dynamic and selectively permeable structure to enable bidirectional and differential movement of essential nutrients, metabolites, and biosynthetic intermediates, vital for growth and survival of host and symbiont. However, despite this crucial role, the molecular basis of membrane transport across the symbiosomal membrane remains unresolved in all bacteriocyte-containing insects. A transport protein was immunolocalized to the symbiosomal membrane separating the pea aphid Acyrthosiphon pisum from its intracellular symbiont Buchnera aphidicola The transporter, A. pisum nonessential amino acid transporter 1, or ApNEAAT1 (gene: ACYPI008971), was characterized functionally following heterologous expression in Xenopus oocytes, and mediates both inward and outward transport of small dipolar amino acids (serine, proline, cysteine, alanine, glycine). Electroneutral ApNEAAT1 transport is driven by amino acid concentration gradients and is not coupled to transmembrane ion gradients. Previous metabolite profiling of hemolymph and bacteriocyte, alongside metabolic pathway analysis in host and symbiont, enable prediction of a physiological role for ApNEAAT1 in bidirectional host-symbiont amino acid transfer, supplying both host and symbiont with indispensable nutrients and biosynthetic precursors to facilitate metabolic complementarity.

RevDate: 2019-08-02

Armaleo D, Müller O, Lutzoni F, et al (2019)

The lichen symbiosis re-viewed through the genomes of Cladonia grayi and its algal partner Asterochloris glomerata.

BMC genomics, 20(1):605 pii:10.1186/s12864-019-5629-x.

BACKGROUND: Lichens, encompassing 20,000 known species, are symbioses between specialized fungi (mycobionts), mostly ascomycetes, and unicellular green algae or cyanobacteria (photobionts). Here we describe the first parallel genomic analysis of the mycobiont Cladonia grayi and of its green algal photobiont Asterochloris glomerata. We focus on genes/predicted proteins of potential symbiotic significance, sought by surveying proteins differentially activated during early stages of mycobiont and photobiont interaction in coculture, expanded or contracted protein families, and proteins with differential rates of evolution.

RESULTS: A) In coculture, the fungus upregulated small secreted proteins, membrane transport proteins, signal transduction components, extracellular hydrolases and, notably, a ribitol transporter and an ammonium transporter, and the alga activated DNA metabolism, signal transduction, and expression of flagellar components. B) Expanded fungal protein families include heterokaryon incompatibility proteins, polyketide synthases, and a unique set of G-protein α subunit paralogs. Expanded algal protein families include carbohydrate active enzymes and a specific subclass of cytoplasmic carbonic anhydrases. The alga also appears to have acquired by horizontal gene transfer from prokaryotes novel archaeal ATPases and Desiccation-Related Proteins. Expanded in both symbionts are signal transduction components, ankyrin domain proteins and transcription factors involved in chromatin remodeling and stress responses. The fungal transportome is contracted, as are algal nitrate assimilation genes. C) In the mycobiont, slow-evolving proteins were enriched for components involved in protein translation, translocation and sorting.

CONCLUSIONS: The surveyed genes affect stress resistance, signaling, genome reprogramming, nutritional and structural interactions. The alga carries many genes likely transferred horizontally through viruses, yet we found no evidence of inter-symbiont gene transfer. The presence in the photobiont of meiosis-specific genes supports the notion that sexual reproduction occurs in Asterochloris while they are free-living, a phenomenon with implications for the adaptability of lichens and the persistent autonomy of the symbionts. The diversity of the genes affecting the symbiosis suggests that lichens evolved by accretion of many scattered regulatory and structural changes rather than through introduction of a few key innovations. This predicts that paths to lichenization were variable in different phyla, which is consistent with the emerging consensus that ascolichens could have had a few independent origins.

RevDate: 2019-07-25

Ruiz B, Le Scornet A, Sauviac L, et al (2019)

The Nitrate Assimilatory Pathway in Sinorhizobium meliloti: Contribution to NO Production.

Frontiers in microbiology, 10:1526.

The interaction between rhizobia and their legume host plants culminates in the formation of specialized root organs called nodules in which differentiated endosymbiotic bacteria (bacteroids) fix atmospheric nitrogen to the benefit of the plant. Interestingly, nitric oxide (NO) has been detected at various steps of the rhizobium-legume symbiosis where it has been shown to play multifaceted roles. It is recognized that both bacterial and plant partners of the Sinorhizobium meliloti-Medicago truncatula symbiosis are involved in NO synthesis in nodules. S. meliloti can also produce NO from nitrate when living as free cells in the soil. S. meliloti does not possess any NO synthase gene in its genome. Instead, the denitrification pathway is often described as the main driver of NO production with nitrate as substrate. This pathway includes the periplasmic nitrate reductase (Nap) which reduces nitrate into nitrite, and the nitrite reductase (Nir) which reduces nitrite into NO. However, additional genes encoding putative nitrate and nitrite reductases (called narB and nirB, respectively) have been identified in the S. meliloti genome. Here we examined the conditions where these genes are expressed, investigated their involvement in nitrate assimilation and NO synthesis in culture and their potential role in planta. We found that narB and nirB are expressed under aerobic conditions in absence of ammonium in the medium and most likely belong to the nitrate assimilatory pathway. Even though these genes are clearly expressed in the fixation zone of legume root nodule, they do not play a crucial role in symbiosis. Our results support the hypothesis that in S. meliloti, denitrification remains the main enzymatic way to produce NO while the assimilatory pathway involving NarB and NirB participates indirectly to NO synthesis by cooperating with the denitrification pathway.

RevDate: 2019-07-25

Nouioui I, Cortés-Albayay C, Carro L, et al (2019)

Genomic Insights Into Plant-Growth-Promoting Potentialities of the Genus Frankia.

Frontiers in microbiology, 10:1457.

This study was designed to determine the plant growth promoting (PGP) potential of members of the genus Frankia. To this end, the genomes of 21 representative strains were examined for genes associated directly or indirectly with plant growth. All of the Frankia genomes contained genes that encoded for products associated with the biosynthesis of auxins [indole-3-glycerol phosphate synthases, anthranilate phosphoribosyltransferases (trpD), anthranilate synthases, and aminases (trpA and B)], cytokinins (11 well-conserved genes within the predicted biosynthetic gene cluster), siderophores, and nitrogenases (nif operon except for atypical Frankia) as well as genes that modulate the effects of biotic and abiotic environmental stress (e.g., alkyl hydroperoxide reductases, aquaporin Z, heat shock proteins). In contrast, other genes were associated with strains assigned to one or more of four host-specific clusters. The genes encoding for phosphate solubilization (e.g., low-affinity inorganic phosphate transporters) and lytic enzymes (e.g., cellulases) were found in Frankia cluster 1 genomes, while other genes were found only in cluster 3 genomes (e.g., alkaline phosphatases, extracellular endoglucanases, pectate lyases) or cluster 4 and subcluster 1c genomes (e.g., NAD(P) transhydrogenase genes). Genes encoding for chitinases were found only in the genomes of the type strains of Frankia casuarinae, F. inefficax, F. irregularis, and F. saprophytica. In short, these in silico genome analyses provide an insight into the PGP abilities of Frankia strains of known taxonomic provenance. This is the first study designed to establish the underlying genetic basis of cytokinin production in Frankia strains. Also, the discovery of additional genes in the biosynthetic gene cluster involved in cytokinin production opens up the prospect that Frankia may have novel molecular mechanisms for cytokinin biosynthesis.

RevDate: 2019-07-23

Gilbert SF (2019)

Developmental symbiosis facilitates the multiple origins of herbivory.

Evolution & development [Epub ahead of print].

Developmental bias toward particular evolutionary trajectories can be facilitated through symbiosis. Organisms are holobionts, consisting of zygote-derived cells and a consortia of microbes, and the development, physiology, and immunity of animals are properties of complex interactions between the zygote-derived cells and microbial symbionts. Such symbionts can be agents of developmental plasticity, allowing an organism to develop in particular directions. This plasticity can lead to genetic assimilation either through the incorporation of microbial genes into host genomes or through the direct maternal transmission of the microbes. Such plasticity can lead to niche construction, enabling the microbes to remodel host anatomy and/or physiology. In this article, I will focus on the ability of symbionts to bias development toward the evolution of herbivory. I will posit that the behavioral and morphological manifestations of herbivorous phenotypes must be preceded by the successful establishment of a community of symbiotic microbes that can digest cell walls and detoxify plant poisons. The ability of holobionts to digest plant materials can range from being a plastic trait, dependent on the transient incorporation of environmental microbes, to becoming a heritable trait of the holobiont organism, transmitted through the maternal propagation of symbionts or their genes.

RevDate: 2019-07-23

Singh RP (2019)

Glycan utilisation system in Bacteroides and Bifidobacteria and their roles in gut stability and health.

Applied microbiology and biotechnology pii:10.1007/s00253-019-10012-z [Epub ahead of print].

Gut residential hundred trillion microbial cells are indispensable for maintaining gut homeostasis and impact on host physiology, development and immune systems. Many of them have displayed excellence in utilising dietary- and host-derived complex glycans and are producing useful postbiotics including short-chain fatty acids to primarily fuel different organs of the host. Therefore, employing individual microbiota is nowadays becoming a propitious target in biomedical for improving gut dysbiosis conditions of the host. Among other gut microbial communities, Bacteroides and Bifidobacteria are coevolved to utilise diverse ranges of diet- and host-derived glycans through harmonising distinct glycan utilisation systems. These gut symbionts frequently share digested oligosaccharides, carbohydrate-active enzymes and fermentable intermediate molecules for sustaining gut microbial symbiosis and improving fitness of own or other communities. Genomics approaches have provided unprecedented insights into these functions, but their precise mechanisms of action have poorly known. Sympathetic glycan-utilising strategy of each gut commensal will provide overview of mechanistic dynamic nature of the gut environment and will then assist in applying aptly personalised nutritional therapy. Thus, the review critically summarises cutting edge understanding of major plant- and host-derived glycan-utilising systems of Bacteroides and Bifidobacteria. Their evolutionary adaptation to gut environment and roles of postbiotics in human health are also highlighted.

RevDate: 2019-07-26

Guckes KR, Cecere AG, Wasilko NP, et al (2019)

Incompatibility of Vibrio fischeri strains during symbiosis establishment depends on two functionally redundant hcp genes.

Journal of bacteriology pii:JB.00221-19 [Epub ahead of print].

Bacteria that have the capacity to fill the same niche will compete with one another for space and resources available within an ecosystem. Such competition is heightened among different strains of the same bacterial species. Nevertheless, different strains often inhabit the same host. The molecular mechanisms that impact competition between different strains within the same host are poorly understood. To address this knowledge gap, the type VI secretion system (T6SS), which is a mechanism for bacteria to kill neighboring cells, was examined in the marine bacterium Vibrio fischeri Different strains of V. fischeri naturally colonize the light organ of the bobtail squid Euprymna scolopes The genome of FQ-A001, which is a T6SS-positive strain, features two hcp genes that are predicted to encode identical subunits of the T6SS. Co-incubation assays showed that either hcp gene is sufficient for FQ-A001 to kill another strain via T6SS in vitro Additionally, induction of hcp expression is sufficient to induce killing activity in an Hcp- mutant of FQ-A001. Squid colonization assays involving inoculums of FQ-A001-derived strains mixed with ES114 revealed that both hcp genes must be deleted for FQ-A001 and ES114 to occupy the same space within the light organ. These experimental results provide insight into the genetic factors necessary for the T6SS of V. fischeri to function in vivo, thereby increasing understanding of the molecular mechanisms that impact strain diversity within a host.IMPORTANCE Different bacterial strains compete to occupy the same niche. The outcome from such competition can be affected by the type VI secretion system (T6SS), which is an intercellular killing mechanism of bacteria. Here, an animal-bacterial symbiosis is used as a platform to study the genetic factors that promote T6SS-mediated killing of one strain by another strain. Identification of the molecular determinants of T6SS function in vivo contributes to the understanding of how different strains interact within a host.

RevDate: 2019-07-23

Lynch JB, Schwartzman JA, Bennett BD, et al (2019)

Ambient pH alters protein content of outer membrane vesicles, driving host development in a beneficial symbiosis.

Journal of bacteriology pii:JB.00319-19 [Epub ahead of print].

Outer membrane vesicles (OMVs) are continuously produced by Gram-negative bacteria, and are increasingly recognized as ubiquitous mediators of bacterial physiology. In particular, OMVs are powerful effectors in inter-organismal interactions, driven largely by their molecular contents. These impacts have been studied extensively in bacterial pathogenesis, but have not been well documented within the context of mutualism. Here, we examined the proteomic composition of OMVs from the marine bacterium Vibrio fischeri, which forms a specific mutualism with the Hawaiian bobtail squid, Euprymna scolopes We found that V. fischeri upregulates transcription of its major outer membrane protein, OmpU, during growth at an acidic pH, which V. fischeri experiences when it transitions from its environmental reservoir to host tissues. We used comparative genomics and DNA pull-down analyses to search for regulators of ompU, and found that differential expression of ompU is governed by the OmpR, H-NS, and ToxR proteins. This transcriptional control combines with nutritional conditions to govern OmpU levels in OMVs. Under a host-encountered acidic pH, V. fischeri OMVs become more potent stimulators of symbiotic host development in an OmpU-dependent manner. Finally, we found that symbiotic development could be stimulated by OMVs containing a homolog of OmpU from the pathogenic species Vibrio cholerae, connecting the role of a well-described virulence factor with a mutualistic element. This work explores the symbiotic effects of OMV variation, identifies shared regulatory machinery between pathogenic and mutualistic bacteria, and provides evidence of the role that OMVs play in animal-bacteria mutualism.Importance Beneficial bacteria communicate with their hosts through a variety of means. These communications are often carried out by a combination of molecules that stimulate responses from the host and are necessary for development of the relationship between these organisms. Naturally produced bacterial outer membrane vesicles (OMVs) contain many of those molecules and can stimulate a wide range of responses from recipient organisms. Here, we describe how a marine bacterium, Vibrio fischeri, changes the makeup of its OMVs under conditions that it experiences as it goes from its free-living lifestyle to associating with its natural host, the Hawaiian bobtail squid. This work improves our understanding of how bacteria change their signaling profile as they begin to associate with their beneficial partner animals.

RevDate: 2019-07-22

Ji J, Luo CL, Zou X, et al (2019)

Association of host genetics with intestinal microbial relevant to body weight in a chicken F2 resource population.

Poultry science pii:5479399 [Epub ahead of print].

Host-microbiota interactions describe a co-evolution and mutualistic symbiosis. Gut microbial communities are important for diverse host functions. However, in birds, the relationship between the composition of the intestinal microbiota and the genetic variation of the host is not clearly understood. To dissect these interactions, a Chinese yellow broiler line (genetically selected for a high growth rate) and Huiyang Beard chickens (low growth rate) were crossed, generating an F2 population. The population structures of the gut microbes in the phenotypically high and low 91-d body weight individuals of both sexes in the F2 population were studied. Interestingly, a non-metric multidimensional scaling analysis revealed that the microbiota of the high-weight and low-weight females was clearly separated into 2 clusters. A β-diversity analysis showed that the locus rs16775833 within the doublesex and mab-3-related transcription factor (DMRT) gene cluster accounted for approximately 21% of the variation in the population structure of the gut microbiota. Furthermore, the 2 genetic loci rs15142709 and rs15142674 were significantly associated with specific species of Methanobacterium. These loci are located in the pleiomorphic adenoma gene 1 (PLAG1) and lck/yes-related novel tyrosine kinase (LYN) genes, which are involved in cell differentiation and growth. This finding suggests evidence for the influence of the host genetics on the composition of the gut microbiota in birds and the importance and utility of the host-microbe status to better understand its effect on the potential growth of birds.

RevDate: 2019-07-22

Cardós JLH, Prieto M, Jylhä M, et al (2019)

A case study on the re-establishment of the cyanolichen symbiosis: where do the compatible photobionts come from?.

Annals of botany pii:5479856 [Epub ahead of print].

BACKGROUND AND AIMS: In order to re-establish lichen symbiosis, fungal spores must first germinate and then associate with a compatible photobiont. To detect possible establishment limitations in a sexually reproducing cyanolichen species, we studied ascospore germination, photobiont growth and photobiont association patterns in Pectenia plumbea.

METHODS: Germination tests were made with ascospores from 500 apothecia under different treatments, and photobiont growth was analysed in 192 isolates obtained from 24 thalli. We determined the genotype identity [tRNALeu (UAA) intron] of the Nostoc cyanobionts from 30 P. plumbea thalli from one population. We also sequenced cyanobionts of 41 specimens of other cyanolichen species and 58 Nostoc free-living colonies cultured from the bark substrate.

KEY RESULTS: Not a single fungal ascospore germinated and none of the photobiont isolates produced motile hormogonia. Genetic analyses revealed that P. plumbea shares Nostoc genotypes with two other cyanolichen species of the same habitat, but these photobionts were hardly present in the bark substrate.

CONCLUSIONS: Due to the inability of both symbionts to thrive independently, the establishment of P. plumbea seems to depend on Dendriscocaulon umhausense, the only cyanolichen species in the same habitat that reproduces asexually and acts as a source of appropriate cyanobionts. This provides support to the hypothesis about facilitation among lichens.

RevDate: 2019-07-22

Muñoz-Gómez SA, Durnin K, Eme L, et al (2019)

Nephromyces represents a diverse and novel lineage of the Apicomplexa that has retained apicoplasts.

Genome biology and evolution pii:5536766 [Epub ahead of print].

A most interesting exception within the parasitic Apicomplexa is Nephromyces, an extracellular, probably mutualistic, endosymbiont found living inside molgulid ascidian tunicates (i.e., sea squirts). Even though Nephromyces is now known to be an apicomplexan, many other questions about its nature remain unanswered. To gain further insights into the biology and evolutionary history of this unusual apicomplexan, we aimed to (1) find the precise phylogenetic position of Nephromyces within the Apicomplexa, (2) search for the apicoplast genome of Nephromyces, and (3) infer the major metabolic pathways in the apicoplast of Nephromyces. To do this, we sequenced a metagenome and a metatranscriptome from the molgulid renal sac, the specialized habitat where Nephromyces thrives. Our phylogenetic analyses of conserved nucleus-encoded genes robustly suggest that Nephromyces is a novel lineage sister to the Hematozoa, which comprises both the Haemosporidia (e.g., Plasmodium) and the Piroplasmida (e.g., Babesia and Theileria). Furthermore, a survey of the renal sac metagenome revealed 13 small contigs that closely resemble the genomes of the non-photosynthetic reduced plastids, or apicoplasts, of other apicomplexans. We show that these apicoplast genomes correspond to a diverse set of most closely related but genetically divergent Nephromyces lineages that co-inhabit a single tunicate host. In addition, the apicoplast of Nephromyces appears to have retained all biosynthetic pathways inferred to have been ancestral to parasitic apicomplexans. Our results shed light on the evolutionary history of the only probably mutualistic apicomplexan known, Nephromyces, and provide context for a better understanding of its life style and intricate symbiosis.

RevDate: 2019-07-22

Khemaissia H, Jelassi R, Ghemari C, et al (2019)

Effects of trace metal elements on ultrastructural features of hepatopancreas of Armadillidium granulatum Brandt, 1833 (Crustacea, Isopoda).

Microscopy research and technique [Epub ahead of print].

This study was conducted to compare metals bioaccumulation in the terrestrial isopod Armadillidium granulatum collected from Ghar El Melh lagoon. We focused on recognizing the effects of trace elements on hepatopancreas functional role. To this end, isopod specimens were exposed for 3 weeks to sediments contaminated with cadmium, copper, zinc, mercury, and nickel. Three concentrations were used in duplicate for each experimental condition. At the end of the experiment, metal body burdens were determined using flame atomic absorption spectrometry. Results of the bioaccumulation factor (BAF) showed that the species A. granulatum was classified as a Cu macroconcentrator (BAF > 2) and a Zn deconcentrator (BAF < 2). Dose dependent morphological and histological changes were observed in the hepatopancreas cells using transmission electron microscopy. The predominant features were: microvillus border disruption, condensation of the cytoplasm with increasing endoplasmic reticulum, mitochondria, lysosomes and granules that accumulated metals in B and S cells. The number of lipid droplets decreased especially after Cd, Zn, Hg, and Ni treatments. This study demonstrated that the terrestrial isopod A. gramulatum could be a good indicator of soil metal contamination.

RevDate: 2019-07-25

Xie L, Chen YL, Long YY, et al (2019)

Three new species of Conlarium from sugarcane rhizosphere in southern China.

MycoKeys, 56:1-11 pii:35857.

Three new species isolated from sugarcane rhizosphere in China, namely Conlariumbaiseensesp. nov., C.nanningensesp. nov., and C.saccharisp. nov., are described and illustrated. Molecular evidence (phylogenetic analysis of combined LSU, SSU, ITS and RPB2 sequence data) and phenotypical characters support their independent status from related and similar species. The new species, as dark spetate endophytes, inhabit sugarcane rhizosphere and can form a symbiosis with sugarcane.

RevDate: 2019-07-21

Fileccia V, Ingraffia R, Amato G, et al (2019)

Identification of microRNAS differentially regulated by water deficit in relation to mycorrhizal treatment in wheat.

Molecular biology reports pii:10.1007/s11033-019-04974-6 [Epub ahead of print].

Arbuscular mycorrhizal fungi (AMF) are soil microrganisms that establish symbiosis with plants positively influencing their resistance to abiotic stresses. The aim of this work was to identify wheat miRNAs differentially regulated by water deficit conditions in presence or absence of AMF treatment. Small RNA libraries were constructed for both leaf and root tissues considering four conditions: control (irrigated) or water deficit in presence/absence of mycorrhizal (AMF) treatment. A total of 12 miRNAs were significantly regulated by water deficit in leaves: five in absence and seven in presence of AMF treatment. In roots, three miRNAs were water deficit-modulated in absence of mycorrhizal treatment while six were regulated in presence of it. The most represented miRNA family was miR167 that was regulated by water deficit in both leaf and root tissues. Interestingly, miR827-5p was differentially regulated in leaves in the absence of mycorrhizal treatment while it was water deficit-modulated in roots irrespective of AMF treatment. In roots, water deficit repressed miR827-5p, miR394, miR6187, miR167e-3p, and miR9666b-3p affecting transcription, RNA synthesis, protein synthesis, and protein modifications. In leaves, mycorrhizae modulated miR5384-3p and miR156e-3p affecting trafficking and cell redox homeostasis. DNA replication and transcription regulation should be targeted by the repression of miR1432-5p and miR166h-3p. This work provided interesting insights into the post-transcriptional mechanisms of wheat responses to water deficit in relation to mycorrhizal symbiosis.

RevDate: 2019-07-20

Zhang S, Kondorosi É, A Kereszt (2019)

An anthocyanin marker for direct visualization of plant transformation and its use to study nitrogen-fixing nodule development.

Journal of plant research pii:10.1007/s10265-019-01126-6 [Epub ahead of print].

The development and functioning of the nitrogen fixing symbiosis between legume plants and soil bacteria collectively called rhizobia requires continuous chemical dialogue between the partners using different molecules such as flavonoids, lipo-chitooligosaccharides, polysaccharides and peptides. Agrobacterium rhizogenes mediated hairy root transformation of legumes is widely used to study the function of plant genes involved in the process. The identification of transgenic plant tissues is based on antibiotics/herbicide selection and/or the detection of different reporter genes that usually require special equipment such as fluorescent microscopes or destructive techniques and chemicals to visualize enzymatic activity. Here, we developed and efficiently used in hairy root experiments binary vectors containing the MtLAP1 gene driven by constitutive and tissue-specific promoters that facilitate the production of purple colored anthocyanins in transgenic tissues and thus allowing the identification of transformed roots by naked eye. Anthocyanin producing roots were able to establish effective symbiosis with rhizobia. Moreover, it was shown that species-specific allelic variations and a mutation preventing posttranslational acetyl modification of an essential nodule-specific cysteine-rich peptide, NCR169, do not affect the symbiotic interaction of Medicago truncatula cv. Jemalong with Sinorhizobium medicae strain WSM419. Based on the experiments, it could be concluded that it is preferable to use the vectors with tissue-specific promoters that restrict anthocyanin production to the root vasculature for studying biotic interactions of the roots such as symbiotic nitrogen fixation or mycorrhizal symbiosis.

RevDate: 2019-07-20

Faluaburu MS, Nakai R, Imura S, et al (2019)

Phylotypic Characterization of Mycobionts and Photobionts of Rock Tripe Lichen in East Antarctica.

Microorganisms, 7(7): pii:microorganisms7070203.

Saxicolous rock ripe lichens that grow on rocks in the East Antarctic fellfields were sampled for phylotypic characterization of its constituent mycobionts (fungi) and photobionts (algae and cyanobacteria). The rock tripe lichen-forming fungal and algal phylotypes were classified under the common lichen-forming genera of ascomycetes, namely, Umbilicaria, and green algae, namely, Trebouxia and Coccomyxa. However, phylotypes of the green algal chloroplasts and the lichen-associated cyanobacteria showed unexpectedly high diversity. The detected chloroplast phylotypes were not fully affiliated with the green algal genera Trebouxia or Coccomyxa. The predominant chloroplast phylotype demonstrated maximum resemblance to Neglectella solitaria, which is neither a known Antarctic species nor a typical lichen photobiont. Another dominant chloroplast phylotype belonged to the atypical Antarctic green algae family. Cyanobacterial phylotypes were dominated by those affiliated with the Microcoleus species rather than the well-known lichen-associates, Nostoc species. The occurrences of these Microcoleus-affiliated cyanobacterial phylotypes were specifically abundant within the Yukidori Valley site, one of the Antarctic Specially Protected Areas (ASPA). The ASPA site, along with another 50 km-distant site, yielded most of the cryptic diversity in the phylotypes of chloroplasts and cyanobacteria, which may contribute to the phenotypic variability within the rock tripe lichen photobionts.

RevDate: 2019-07-26

Morishima SY, Yamashita H, O-Hara S, et al (2019)

Study on expelled but viable zooxanthellae from giant clams, with an emphasis on their potential as subsequent symbiont sources.

PloS one, 14(7):e0220141 pii:PONE-D-19-11506.

Unlike most bivalve shellfishes, giant clams (tridacnines) harbor symbiotic microalgae (zooxanthellae) in their fleshy bodies. Zooxanthellae are not maternally inherited by tridacnine offspring, hence, the larvae must acquire zooxanthellae from external sources, although such algal populations or sources in the environment are currently unknown. It is well known that giant clams expel fecal pellets that contain viable zooxanthellae cells, but whether these cells are infectious or just an expelled overpopulation from the giant clams has not been investigated. In this study, we observed the ultrastructural and photosynthetic competencies of zooxanthellae in the fecal pellets of Tridacna crocea and further tested the ability of these cells to infect T. squamosa juveniles. The ultrastructure of the zooxanthellae cells showed that the cells were intact and had not undergone digestion. Additionally, these zooxanthellae cells showed a maximum quantum yield of photosystem II (Fv/Fm) as high as those retained in the mantle of the giant clam. Under the assumption that feces might provide symbionts to the larvae of other giant clams, fecal pellets from Tridacna squamosa and T. crocea were given to artificially hatched 1-day-old T. squamosa larvae. On the 9th day, 15-34% of the larvae provided with the fecal pellets took up zooxanthellae in their stomach, and on the 14th day, zooxanthellae cells reached the larval margin, indicating the establishment of symbiosis. The rate reaching this stage was highest, ca. 5.3%, in the larvae given whole (nonhomogenized) pellets from T. crocea. The composition of zooxanthellae genera contained in the larvae were similar to those in the fecal pellets, although the abundance ratios were significantly different. This study is the first to demonstrate the potential of giant clam fecal pellets as symbiont vectors to giant clam larvae. These results also demonstrate the possibility that fecal pellets are a source of zooxanthellae in coral reefs.

RevDate: 2019-07-29

Ingavle G, Shabrani N, Vaidya A, et al (2019)

Mimicking megakaryopoiesis in vitro using biomaterials: Recent advances and future opportunities.

Acta biomaterialia pii:S1742-7061(19)30514-8 [Epub ahead of print].

Presently donor-derived platelets used in the clinic are associated with concerns about adequate availability, expense, risk of bacterial contamination and complications due to immunological reaction. To prevail over our dependence on transfusion of donor-derived platelets, efforts are being made to generate them in vitro. Development of biomaterials that support or mimic bone marrow niche micro-environmental cues could improve the in vitro production of platelets from megakaryocytes (MKs) derived from various stem cell sources. In spite of significant advances in the production of MKs from various stem cell sources using 2D as well as 3D culture approaches in vitro and the development of biomaterials-based platelet systems, yield and quality of these platelets remains unsuitable for clinical use. Thus, in vitro production of clinically useful platelets on a large scale remains an unmet target to date. This review summarizes the most frequently used 2D and 3D approaches to generate MKs and platelets in vitro, emphasizing the importance of mimicking in vivo micro-environment. Further, this review proposes the use of interpenetrating network (IPN) biomaterial-based approach as a promising strategy for improving the generation of MK and platelets in sufficient numbers in vitro. STATEMENT OF SIGNIFICANCE: Thrombocytopenia is one of the major global health and socio-economic problems. Transfusion with donor-derived platelets (PLTs) is the only effective treatment for this condition. However, this approach is limited by factors like short shelf-life of PLTs, PLT activation, alloimmunization, risk of bacterial contamination, infection etc. In vitro generated MKs and PLTs derived from non-donor-dependent sources may help to overcome the platelet transfusion concerns. Here we have reviewed various 2D and 3D strategies used for in vitro generation of MKs and PLTs, with special emphasis on various biomaterial platforms and different physico/chemical cues being used for the purpose. We have also proposed a biomaterial-based approach of using interpenetrating network (IPN) for generating clinically relevant numbers of MKs and PLTs.

RevDate: 2019-08-02

Ali HRK, Hemeda NF, YF Abdelaliem (2019)

Symbiotic cellulolytic bacteria from the gut of the subterranean termite Psammotermes hypostoma Desneux and their role in cellulose digestion.

AMB Express, 9(1):111 pii:10.1186/s13568-019-0830-5.

The subterranean termite Psammotermes hypostoma Desneux is considered as an important pest that could cause severe damage to buildings, furniture, silos of grain and crops or any material containing cellulose. This species of termites is widespread in Egypt and Africa. The lower termite's ability to digest cellulose depends on the association of symbiotic organisms gut that digest cellulose (flagellates and bacteria). In this study, 33 different bacterial isolates were obtained from the gut of the termite P. hypostoma which were collected using cellulose traps. Strains were grown on carboxymethylcellulose (CMC) as a sole source of carbon. Cellulolytic strains were isolated in two different cellulose medium (mineral salt medium containing carboxymethylcellulose as the sole carbon source and agar cellulose medium). Five isolates showed significant cellulolytic activity identified by a Congo red assay which gives clear zone. Based on biochemical tests and sequencing of 16s rRNA genes these isolates were identified as Paenibacillus lactis, Lysinibacillus macrolides, Stenotrophomonas maltophilia, Lysinibacillus fusiformis and Bacillus cereus, that deposited in GenBank with accession numbers MG991563, MG991564, MG991565, MG991566 and MG991567, respectively.

RevDate: 2019-07-26

Hoe C, Adhikari B, Glandon D, et al (2019)

Using social network analysis to plan, promote and monitor intersectoral collaboration for health in rural India.

PloS one, 14(7):e0219786 pii:PONE-D-19-03430.

BACKGROUND: As population health and well-being are influenced by multiple factors that cut across sectoral boundaries, an intersectoral approach that acknowledges and leverages the multiple determinants, actors and sectors at play is increasingly seen as critical for achieving meaningful and lasting improvements. In this study, we utilize social network analysis (SNA) to characterize the intersectoral collaboration between the organizations working on maternal & child health (MCH) and water & sanitation (WASH) before and immediately after the implementation of HCL Foundation (HCLF)-funded HCL Samuday Project (2015-2017) in a rural block of Uttar Pradesh state, India. While SNA has been used to examine public health issues, few have used it monitor stakeholder relationships, intervene, improve and facilitate project implementation involving intersectoral partnerships, particularly in the context of a low-and middle-income countries.

METHOD: An organization-level SNA was conducted with 31 key informants from 24 organizations working on MCH and/or WASH in Kachhauna, Uttar Pradesh, India. Data were collected using face-to-face, semi-structured interviews between June and September 2017. Density, centrality and homophily were calculated to describe the network and a qualitative analysis was also conducted to identify the strengths and weaknesses of collaboration between organizations working on MCH and WASH.

RESULTS: Overall, our findings showed that the network of organizations working on MCH and WASH in Kachhauna grew in number since the implementation of Samuday. HCLF rapidly achieved centrality, thus positioning the organization to serve as a gatekeeper of information and enabling it to play a coordinator role within the network. Direct collaboration between other organizations working on MCH and WASH was low at both time points. Interviews with key informants indicated widespread interest in increasing interorganizational interactions and engagement throughout the network.

CONCLUSION: This study demonstrates the feasibility and practical application of SNA for projects like Samuday that involve intersectoral collaboration. It also provides lessons about the use of SNA with organizations as the unit of analysis and in the context of rural India, including challenges, practical considerations, and limitations.

RevDate: 2019-07-17

Martínez-Medina A, Fernández I, Pescador L, et al (2019)

Trichoderma harzianum triggers an early and transient burst of nitric oxide and the upregulation of PHYTOGB1 in tomato roots.

Plant signaling & behavior [Epub ahead of print].

We recently demonstrated that nitric oxide (NO) accumulation and PHYTOGB1 transcriptional regulation are early components of the regulatory pathway that is activated in tomato roots during the onset of the mycorrhizal symbiosis between Rhizophagus irregularis and tomato roots. We further showed that the mycorrhizal interaction was associated with a specific NO-related signature, different from that triggered by the pathogen Fusarium oxysporum. Here, we extend our investigation by exploring the NO- and PHYTOGB1-related root responses elicited by another root mutualistic endosymbiotic fungus: Trichoderma harzianum T-78. By using T-78 in vitro-grown cultures, we found that T-78 triggered an early and transient burst of NO in tomato roots during the first hours after the interaction. T-78 also elicited the early upregulation of PHYTOGB1, which was maintained during the analyzed timespan. By using glass-house bioassays, we found that in a well-established tomato-T-78 symbiosis, NO root levels were maintained at basal level while PHYTOGB1 expression remained upregulated. Our results demonstrate that the T-78 symbiosis is associated with a rapid and transient burst of NO in the host roots and the transcriptional activation of PHYTOGB1 from early stages of the interaction until the establishment of the symbiosis, most likely to control NO levels and favor the mutualistic symbiosis.

RevDate: 2019-07-17

Liu M, Soyano T, Yano K, et al (2019)

ERN1 and CYCLOPS coordinately activate NIN signaling to promote infection thread formation in Lotus japonicus.

Journal of plant research pii:10.1007/s10265-019-01122-w [Epub ahead of print].

Legumes engage in symbiosis with nitrogen-fixing soil bacteria, collectively called rhizobia, under nitrogen-limited conditions. In many legumes, the root invasion of rhizobia is mediated by infection threads (ITs), tubular invaginations of the host cell wall and plasma membrane, developed from infection foci of deformed root hairs. IT formation is regulated by a series of signal transduction in host root. Nodulation signals activate the host transcription factor (TF), CYCLOPS, which directly induces expression of two TF genes, ERF REQUIRED FOR NODULATION1 (ERN1) and NODULE INCEPTION (NIN), essential for IT development. Here, we explored the relationship among these three symbiotic TF genes in the model legume Lotus japonicus and examined how their interplay contributes to IT formation. qRT-PCR analysis showed that NIN expression induced by rhizobial infection was attenuated in ern1-1, and further declined in cyclops-3 ern1-1. ERN1 overexpression led to induction of NIN expression in cyclops-3 ern1-1 in the presence of rhizobia. Thus, in addition to CYCLOPS, ERN1 is able to increase the NIN expression level depending on infection. Furthermore, consistent with this transcriptional hierarchy, ectopic expression of ERN1 as well as NIN suppressed the IT-deficient cyclops-3 phenotype, but ERN1 failed to confer ITs in the nin-2 root. However, the ern1-1 symbiotic epidermal phenotype was not suppressed by the NIN ectopic expression. The cyclops-3 ern1-1 double mutant was less sensitive to rhizobial infection than the single mutants and defective in the symbiotic root hair response at earlier stages. This more severe phenotype of the double mutant suggests a role for ERN1 that independent of the CYCLOPS-mediated transcriptional regulation. We conclude that ERN1 is involved in regulating NIN expression in addition to CYCLOPS, and these TFs coordinately promote the symbiotic root hair response and IT development. Our data help to reveal the extensive role of ERN1 in root nodule symbiosis signaling.

RevDate: 2019-07-19

Xie XG, Zhang FM, Yang T, et al (2019)

Endophytic Fungus Drives Nodulation and N2 Fixation Attributable to Specific Root Exudates.

mBio, 10(4): pii:mBio.00728-19.

Endophytic fungi play important roles in the modification of ecosystem productivity; however, the underlying mechanisms are only partly understood. A 2-year field plot experiment verified that the endophytic fungus Phomopsis liquidambaris increased peanut (Arachis hypogaea L.) yields and significantly increased nodulation and N2 fixation regardless of whether N fertilizers were added. Root exudates collected from P. liquidambaris-colonized plants significantly improved nodulation and N2 fixation. Rhizosphere stimulation experiments further showed that colonized root exudates had significantly decreased soil nitrate (NO3-) concentrations, with decreased abundance and diversity of ammonia oxidizing archaea (AOA). In contrast, the abundance and diversity of diazotrophs significantly increased, and most diazotrophs identified were peanut nodulation-related strains (Bradyrhizobium sp.). P. liquidambaris symbiosis increased the expression of phenolic and flavonoid synthesis-related genes, and the derived phenolics and flavonoids could effectively increase the chemotaxis, biofilm formation, and nodC gene expression (nodulation-related biological processes) of the Bradyrhizobium strain. Metabolic pattern analysis showed that phenolics and flavonoids are more likely to accumulate to higher levels in the rhizosphere soil of peanuts colonized with P. liquidambaris Finally, a synthetic root exudate experiment further confirmed the underlying mechanisms for the P. liquidambaris-induced improvement in nodulation and N2 fixation, i.e., that the specific root exudates derived from P. liquidambaris colonization decrease nitrate concentration and increase the population and biological activities of peanut nodulation-related Bradyrhizobium species, which beneficially enhance peanut-Bradyrhizobium interactions. Therefore, this study is the first to provide new insight into a positive relationship between an exotic endophytic fungus, crop nodulation, and N2 fixation increase.IMPORTANCE Endophytic fungi play an important role in balancing the ecosystem and boosting host growth; however, the underpinning mechanisms remain poorly understood. Here, we found that endophytic fungal colonization with P. liquidambaris significantly increased the productivity, nodulation, and N2 fixation of peanuts through the secretion of specific root exudates. We provide a reasonable mechanism explaining how P. liquidambaris promotes peanut nodulation and N2 fixation, whereby the specific root exudates produced by P. liquidambaris colonization decrease rhizosphere soil nitrate (NO3-) and increase the population and biological activities of peanut-nodulating-related Bradyrhizobium strains, which is beneficial to enhancing the peanut-Bradyrhizobium symbiotic interaction. Our study provides reliable empirical evidence to show the mechanism of how an exotic endophytic fungus drives an increase in nodulation and N2 fixation, which will be helpful in erecting a resource-efficient and sustainable agricultural system.

RevDate: 2019-07-26

Sinnesael A, Leroux O, Janssens SB, et al (2019)

Is the bacterial leaf nodule symbiosis obligate for Psychotria umbellata? The development of a Burkholderia-free host plant.

PloS one, 14(7):e0219863 pii:PONE-D-19-07425.

BACKGROUND & AIMS: The bacterial leaf nodule symbiosis is an interaction where bacteria are housed in specialised structures in the leaves of their plant host. In the Rubiaceae plant family, host plants interact with Burkholderia bacteria. This interaction might play a role in the host plant defence system. It is unique due to its high specificity; the vertical transmission of the endophyte to the next generation of the host plant; and its supposedly obligatory character. Although previous attempts have been made to investigate this obligatory character by developing Burkholderia-free plants, none have succeeded and nodulating plants were still produced. In order to investigate the obligatory character of this endosymbiosis, our aims were to develop Burkholderia-free Psychotria umbellata plants and to investigate the effect of the absence of the endophytes on the host in a controlled environment.

METHODS: The Burkholderia-free plants were obtained via embryo culture, a plant cultivation technique. In order to analyse the endophyte-free status, we screened the plants morphologically, microscopically and molecularly over a period of three years. To characterise the phenotype and growth of the in vitro aposymbiotic plants, we compared the growth of the Burkholderia-free plants to the nodulating plants under the same in vitro conditions.

KEY RESULTS: All the developed plants were Burkholderia-free and survived in a sterile in vitro environment. The growth analysis showed that plants without endophytes had a slower development.

CONCLUSIONS: Embryo culture is a cultivation technique with a high success rate for the development of Burkholderia-free plants of P. umbellata. The increased growth rate in vitro when the specific endophyte is present cannot be explained by possible benefits put forward in previous studies. This might indicate that the benefits of the endosymbiosis are not yet completely understood.

RevDate: 2019-07-23

Bonfante P (2019)

Algae and fungi move from the past to the future.

eLife, 8: pii:49448.

The ability of photosynthetic algae to enter the hyphae of a soil fungus could tell us more about the evolution of these species and their potential for applications in the production of biofuel.

RevDate: 2019-07-23

Du ZY, Zienkiewicz K, Vande Pol N, et al (2019)

Algal-fungal symbiosis leads to photosynthetic mycelium.

eLife, 8: pii:47815.

Mutualistic interactions between free-living algae and fungi are widespread in nature and are hypothesized to have facilitated the evolution of land plants and lichens. In all known algal-fungal mutualisms, including lichens, algal cells remain external to fungal cells. Here, we report on an algal-fungal interaction in which Nannochloropsis oceanica algal cells become internalized within the hyphae of the fungus Mortierella elongata. This apparent symbiosis begins with close physical contact and nutrient exchange, including carbon and nitrogen transfer between fungal and algal cells as demonstrated by isotope tracer experiments. This mutualism appears to be stable, as both partners remain physiologically active over months of co-cultivation, leading to the eventual internalization of photosynthetic algal cells, which persist to function, grow and divide within fungal hyphae. Nannochloropsis and Mortierella are biotechnologically important species for lipids and biofuel production, with available genomes and molecular tool kits. Based on the current observations, they provide unique opportunities for studying fungal-algal mutualisms including mechanisms leading to endosymbiosis.


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.

963 Red Tail Lane
Bellingham, WA 98226


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

short personal version

Curriculum Vitae for R J Robbins

long standard version

RJR Picks from Around the Web (updated 11 MAY 2018 )