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Bibliography on: Symbiosis

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ESP: PubMed Auto Bibliography 25 Oct 2021 at 01:52 Created: 

Symbiosis

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®)

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RevDate: 2021-10-22

Qi H, Xia FN, Xiao S, et al (2021)

TRAF proteins as key regulators of plant development and stress responses.

Journal of integrative plant biology [Epub ahead of print].

Tumor necrosis factor receptor-associated factor (TRAF) proteins are conserved in higher eukaryotes and play key roles in transducing cellular signals across different organelles. They are characterized by their C-terminal region (TRAF-C domain) containing seven to eight antiparallel β-sheets, also known as the meprin and TRAF-C homology (MATH) domain. Over the past few decades, significant progress has been made towards understanding the diverse roles of TRAF proteins in mammals and plants. Compared to other eukaryotic species, the Arabidopsis thaliana and rice (Oryza sativa) genomes encode many more TRAF/MATH domain-containing proteins; these plant proteins cluster into five classes: TRAF/MATH-only, MATH-BPM, MATH-UBP, SINA, and MATH-Filament and MATH-PEARLI-4 proteins, suggesting parallel evolution of TRAF proteins in plants. Increasing evidence now indicates that plant TRAF proteins form central signaling networks essential for multiple biological processes, such as vegetative and reproductive development, autophagosome formation, plant immunity, symbiosis, phytohormone signaling, and abiotic stress responses. Here, we summarize recent advances and highlight future prospects for understanding on the molecular mechanisms by which TRAF proteins act in plant development and stress responses. This article is protected by copyright. All rights reserved.

RevDate: 2021-10-22

Pérez-Lachaud G, Rocha FH, Pozo C, et al (2021)

A new ant-butterfly symbiosis in the forest canopy fills an evolutionary gap.

Scientific reports, 11(1):20770.

Myrmecophilous butterflies can establish complex symbiotic relationships with ants. A caterpillar wandering among the brood of the aggressive ponerine ant Neoponera villosa was found inside the core of a nest built in the myrmecophytic bromeliad Aechmea bracteata. This is the first caterpillar found living inside a ponerine ant nest. Its DNA barcode was sequenced, and an integrative approach was used to identify it as Pseudonymphidia agave, a poorly known member of the subtribe Pachythonina in the riodinid tribe Nymphidiini. The cuticle of the tank-like caterpillar lacks projections or tubercles and is covered dorsally by specialized flat setae that form an armor of small plates. Ant-organs potentially related to caterpillar-ant signaling, such as perforated cupola organs and tentacle nectary organs, are present. These morphological traits, together with evidence of social integration (direct contact with host brood, protective morphology, slow movement, no host aggressiveness), suggest that P. agave is a symbiotic, social parasite of N. villosa, preying on its host brood. However, several knowledge gaps remain, including oviposition site, dependence on bromeliad association, steps to colony integration, and larval diet through development. Carnivory has been reported in all known members of the subtribe Pachythonina (caterpillars prey on honeydew-producing hemipterans) suggesting a shift to myrmecophagy inside the ant nests as a possible evolutionary transition.

RevDate: 2021-10-21

Bonthond G, Shalygin S, Bayer T, et al (2021)

Draft genome and description of Waterburya agarophytonicola gen. nov. sp. nov. (Pleurocapsales, Cyanobacteria): a seaweed symbiont.

Antonie van Leeuwenhoek [Epub ahead of print].

This work introduces Waterburya agarophytonicola Bonthond and Shalygin gen. nov., sp. nov, a baeocyte producing cyanobacterium that was isolated from the rhodophyte Agarophyton vermiculophyllum (Ohmi) Gurgel et al., an invasive seaweed that has spread across the northern hemisphere. The new species genome reveals a diverse repertoire of chemotaxis and adhesion related genes, including genes coding for type IV pili assembly proteins and a high number of genes coding for filamentous hemagglutinin family (FHA) proteins. Among a genetic basis for the synthesis of siderophores, carotenoids and numerous vitamins, W. agarophytonicola is potentially capable of producing cobalamin (vitamin B12), for which A. vermiculophyllum is an auxotroph. With a taxonomic description of the genus and species and a draft genome, this study provides as a basis for future research, to uncover the nature of this geographically independent association between seaweed and cyanobiont.

RevDate: 2021-10-21

COVID STEROID 2 Trial Group, Munch MW, Myatra SN, et al (2021)

Effect of 12 mg vs 6 mg of Dexamethasone on the Number of Days Alive Without Life Support in Adults With COVID-19 and Severe Hypoxemia: The COVID STEROID 2 Randomized Trial.

JAMA pii:2785529 [Epub ahead of print].

Importance: A daily dose with 6 mg of dexamethasone is recommended for up to 10 days in patients with severe and critical COVID-19, but a higher dose may benefit those with more severe disease.

Objective: To assess the effects of 12 mg/d vs 6 mg/d of dexamethasone in patients with COVID-19 and severe hypoxemia.

A multicenter, randomized clinical trial was conducted between August 2020 and May 2021 at 26 hospitals in Europe and India and included 1000 adults with confirmed COVID-19 requiring at least 10 L/min of oxygen or mechanical ventilation. End of 90-day follow-up was on August 19, 2021.

Interventions: Patients were randomized 1:1 to 12 mg/d of intravenous dexamethasone (n = 503) or 6 mg/d of intravenous dexamethasone (n = 497) for up to 10 days.

Main Outcomes and Measures: The primary outcome was the number of days alive without life support (invasive mechanical ventilation, circulatory support, or kidney replacement therapy) at 28 days and was adjusted for stratification variables. Of the 8 prespecified secondary outcomes, 5 are included in this analysis (the number of days alive without life support at 90 days, the number of days alive out of the hospital at 90 days, mortality at 28 days and at 90 days, and ≥1 serious adverse reactions at 28 days).

Results: Of the 1000 randomized patients, 982 were included (median age, 65 [IQR, 55-73] years; 305 [31%] women) and primary outcome data were available for 971 (491 in the 12 mg of dexamethasone group and 480 in the 6 mg of dexamethasone group). The median number of days alive without life support was 22.0 days (IQR, 6.0-28.0 days) in the 12 mg of dexamethasone group and 20.5 days (IQR, 4.0-28.0 days) in the 6 mg of dexamethasone group (adjusted mean difference, 1.3 days [95% CI, 0-2.6 days]; P = .07). Mortality at 28 days was 27.1% in the 12 mg of dexamethasone group vs 32.3% in the 6 mg of dexamethasone group (adjusted relative risk, 0.86 [99% CI, 0.68-1.08]). Mortality at 90 days was 32.0% in the 12 mg of dexamethasone group vs 37.7% in the 6 mg of dexamethasone group (adjusted relative risk, 0.87 [99% CI, 0.70-1.07]). Serious adverse reactions, including septic shock and invasive fungal infections, occurred in 11.3% in the 12 mg of dexamethasone group vs 13.4% in the 6 mg of dexamethasone group (adjusted relative risk, 0.83 [99% CI, 0.54-1.29]).

Conclusions and Relevance: Among patients with COVID-19 and severe hypoxemia, 12 mg/d of dexamethasone compared with 6 mg/d of dexamethasone did not result in statistically significantly more days alive without life support at 28 days. However, the trial may have been underpowered to identify a significant difference.

Trial Registration: ClinicalTrials.gov Identifier: NCT04509973 and ctri.nic.in Identifier: CTRI/2020/10/028731.

RevDate: 2021-10-21

Sin Chan S, Shiong Khoo K, Wayne Chew K, et al (2021)

Recent advances biodegradation and biosorption of organic compounds from wastewater: microalgae-bacteria consortium - A Review.

Bioresource technology pii:S0960-8524(21)01501-7 [Epub ahead of print].

The litter of persistent organic pollutants (POPs) into the water streams and soil bodies via industrial effluents led to several adverse effects on the environment, health, and ecosystem. For the past decades, scientists have been paying efforts in the innovation and development of POPs removal from wastewater treatment. However, the conventional methods used for the removal of POPs from wastewater are costly and could lead to secondary pollution including soil and water bodies pollution. In recent, the utilization of green mechanisms such as biosorption, bioaccumulation and biodegradation has drawn attention and prelude the potential of green technology globally. Microalgae-bacteria consortia have emerged to be one of the latent wastewater treatment systems. The synergistic interactions between microalgae and bacteria could proficiently enhance the existing biological wastewater treatment system. This paper will critically review the comparison of conventional and recent advanced wastewater treatment systems and the mechanisms of the microalgae-bacteria symbiosis system.

RevDate: 2021-10-21

Sycheva MV, Popova EV, Khlopko YA, et al (2021)

Genome Analysis of the Probiotic Strain Enterococcus faecium Ef79OSAU.

Microbiology resource announcements, 10(42):e0069121.

We report here the draft genome sequence of Enterococcus faecium strain Ef79OSAU, which was isolated from swine feces. The characteristics of strain Ef79OSAU reveal the absence of pathogenicity factors, a wide range of antimicrobial activity in vitro, and antilisteriosis activity in vivo. Analysis of the E. faecium Ef79OSAU genome revealed a cluster of genes encoding enterocin A without genetic determinants of pathogenicity.

RevDate: 2021-10-22

Acevedo TS, Fricker GP, Garcia JR, et al (2021)

The Importance of Environmentally Acquired Bacterial Symbionts for the Squash Bug (Anasa tristis), a Significant Agricultural Pest.

Frontiers in microbiology, 12:719112.

Most insects maintain associations with microbes that shape their ecology and evolution. Such symbioses have important applied implications when the associated insects are pests or vectors of disease. The squash bug, Anasa tristis (Coreoidea: Coreidae), is a significant pest of human agriculture in its own right and also causes damage to crops due to its capacity to transmit a bacterial plant pathogen. Here, we demonstrate that complete understanding of these insects requires consideration of their association with bacterial symbionts in the family Burkholderiaceae. Isolation and sequencing of bacteria housed in the insects' midgut crypts indicates that these bacteria are consistent and dominant members of the crypt-associated bacterial communities. These symbionts are closely related to Caballeronia spp. associated with other true bugs in the superfamilies Lygaeoidea and Coreoidea. Fitness assays with representative Burkholderiaceae strains indicate that the association can significantly increase survival and decrease development time, though strains do vary in the benefits that they confer to their hosts, with Caballeronia spp. providing the greatest benefit. Experiments designed to assess transmission mode indicate that, unlike many other beneficial insect symbionts, the bacteria are not acquired from parents before or after hatching but are instead acquired from the environment after molting to a later developmental stage. The bacteria do, however, have the capacity to escape adults to be transmitted to later generations, leaving the possibility for a combination of indirect vertical and horizontal transmission.

RevDate: 2021-10-21
CmpDate: 2021-10-21

Pedraza F, J Bascompte (2021)

The joint role of coevolutionary selection and network structure in shaping trait matching in mutualisms.

Proceedings. Biological sciences, 288(1957):20211291.

Coevolution can sculpt remarkable trait similarity between mutualistic partners. Yet, it remains unclear which network topologies and selection regimes enhance trait matching. To address this, we simulate coevolution in topologically distinct networks under a gradient of mutualistic selection strength. We describe three main insights. First, trait matching is jointly influenced by the strength of mutualistic selection and the structural properties of the network where coevolution is unfolding. Second, the strength of mutualistic selection determines the network descriptors better correlated with higher trait matching. While network modularity enhances trait matching when coevolution is weak, network connectance does so when coevolution is strong. Third, the structural properties of networks outrank those of modules or species in determining the degree of trait matching. Our findings suggest networks can both enhance or constrain trait matching, depending on the strength of mutualistic selection.

RevDate: 2021-10-22
CmpDate: 2021-10-22

Kern L, Abdeen SK, Kolodziejczyk AA, et al (2021)

Commensal inter-bacterial interactions shaping the microbiota.

Current opinion in microbiology, 63:158-171.

The gut microbiota, a complex ecosystem of microorganisms of different kingdoms, impacts host physiology and disease. Within this ecosystem, inter-bacterial interactions and their impacts on microbiota community structure and the eukaryotic host remain insufficiently explored. Microbiota-related inter-bacterial interactions range from symbiotic interactions, involving exchange of nutrients, enzymes, and genetic material; competition for nutrients and space, mediated by biophysical alterations and secretion of toxins and anti-microbials; to predation of overpopulating bacteria. Collectively, these understudied interactions hold important clues as to forces shaping microbiota diversity, niche formation, and responses to signals perceived from the host, incoming pathogens and the environment. In this review, we highlight the roles and mechanisms of selected inter-bacterial interactions in the microbiota, and their potential impacts on the host and pathogenic infection. We discuss challenges in mechanistically decoding these complex interactions, and prospects of harnessing them as future targets for rational microbiota modification in a variety of diseases.

RevDate: 2021-10-22
CmpDate: 2021-10-22

Mishra AA, AY Koh (2021)

The microbial and host factors that govern Candida gastrointestinal colonization and dissemination.

Current opinion in microbiology, 63:29-35.

Candida species are among the most prevalent and abundant members of the gut mycobiota, with Candida albicans (CA) being the most prominent member. CA colonizes numerous mucosal surfaces, most notably the gastrointestinal (GI) and genitourinary tracts. In a healthy host, CA is a pathobiont that exists as a commensal but can become pathogenic if the host's immune system becomes suppressed. The microbial and/or host factors that dictate CA's ability to colonize mucosal surfaces and its ability to disseminate remain of great interest. Here, we review the recent advances and insights regarding Candida colonization and dissemination of the mammalian GI tract.

RevDate: 2021-10-21
CmpDate: 2021-10-21

Kim M, Choi DH, MG Park (2021)

Cyanobiont genetic diversity and host specificity of cyanobiont-bearing dinoflagellate Ornithocercus in temperate coastal waters.

Scientific reports, 11(1):9458.

Cyanobacteria are ubiquitous in marine environments and play an important role as primary producers. Some cyanobacteria, the so-called cyanobionts (cyanobacterial symbionts), have a symbiotic relationship with unicellular organisms. Among these relationships, in particular, the nature (e.g., genetic diversity, host or cyanobiont specificity, and cyanobiont seasonality) of the cyanobiont-dinoflagellate host consortia remains poorly understood. In this study, 16S rDNA of cyanobionts in 138 single host cells isolated over four seasons from temperate waters were sequenced using the MiSeq platform. Genetic analysis of cyanobionts from the dinoflagellate host Ornithocercus revealed that three genetic types of Synechococcales cyanobionts occurred in a wide range of water temperatures (11-24 °C), and their distribution seemed to be closely associated with variations in salinity. Furthermore, a certain degree of host (or cyanobiont) specificity in cyanobionts (or the host) among Ornithocercus species as well as among other dinophysoid species (i.e. Amphisolenia, Citharistes, and Histioneis), was observed. In addition to the Synechococcales cyanobionts, this study identified OTU sequences affiliated with Vampirovibrionales and Chroococcidiopsidales in some Ornithocercus cells, suggesting that Ornithocercus species are an additional habitat for these bacterial groups.

RevDate: 2021-10-22
CmpDate: 2021-10-22

Bosman-Schluep D, de Pril R, Verbaken B, et al (2021)

siRNA-based identification of IBD-related targets in human monocyte-derived dendritic cells.

Journal of immunological methods, 494:113058.

Inflammatory bowel disease (IBD) is thought to be caused by an aberrant host response to the commensal enteric flora in genetically susceptible individuals. Dendritic cells (DCs) play a key role in the regulation of this response as they sample gut commensals. In healthy individuals DCs actively contribute to tolerance upon recognition of these resident bacteria, whereas in individuals with IBD, DCs will initiate an inflammatory response. To mimic the disease response in vitro, human monocyte-derived DCs were matured with E. coli causing the cells to produce high levels of the pro-inflammatory cytokine IL-12/IL-23p40 (p40) and low levels of the anti-inflammatory cytokine IL-10. A siRNA-based screening assay was developed and screened to identify potential therapeutic targets that shift this balance towards an immunosuppressive state with lower levels of p40 and higher levels of IL-10. The screening assay was optimized and quality controlled using non-targeting controls and positive control siRNAs targeting IL12B and TLR4 transcripts. In the primary screen, smartpool siRNAs were screened for reduction in p40 expression, induction of IL-10 levels, or increase in IL-10:p40 ratios without affecting cell viability. All potential targets were taken forward into a confirmation screen in a different DC donor in which four individual siRNAs per target were screened. At least two siRNAs per target should have an effect to be considered a valid target. This screen resulted in a concise list of ten genes, of which their role in DC maturation is currently being investigated.

RevDate: 2021-10-22
CmpDate: 2021-10-22

Zhou Z, Zhang K, Wang L, et al (2021)

Nitrogen availability improves the physiological resilience of coral endosymbiont Cladocopium goreaui to high temperature.

Journal of phycology, 57(4):1187-1198.

The physiological response of symbiotic Symbiodiniaceae to high temperature is believed to result in coral bleaching. However, the potential effect of nitrogen availability on heat acclimatization of symbiotic Symbiodiniaceae is still unclear. In this study, physiological responses of Symbiodiniaceae Cladocopium goreaui to temperature and nitrogen nutrient stress conditions were investigated. Nitrogen deficiency caused significant declines in cell concentration and chlorophyll content per cell, but significant increases in nitric oxide synthase activity, caspase3 activation level, and cellular carbon content of C. goreaui at normal temperature. Algal cells under high temperature and nitrogen deficiency showed significant rises in Fv/Fm, catalase activity, and caspase3 activation level, but no significant changes in cell yield, cell size, chlorophyll content, superoxide dismutase, nitric oxide synthase activity, and cellular contents of nitrogen and carbon, in comparison with those under normal temperature and nitrogen deficiency. Growth, chlorophyll, and nitrogen contents of algal cells under the high temperature and nitrogen-replete conditions were significantly higher than those under high temperature or nitrogen deficiency alone, whereas nitric oxide synthase activity, superoxide dismutase activity, catalase activity, carbon content, and caspase3 activation level exhibited opposite trends of variation. Transcriptomic and network analyses revealed ion transport and metabolic processes mainly involved in regulating these physiological activities under different temperature and nitrogen nutrient. The totality of results shows that high temperature activates stress responses, induces antioxidant capacity of apoptosis, and limits the growth rate of C. goreaui. Adequate nitrogen nutrient can improve the resilience of this Symbiodiniaceae against heat stress through repressed apoptosis, promoted ion transport, and optimized metabolism.

RevDate: 2021-10-21
CmpDate: 2021-10-21

Ferguson KB, Visser S, Dalíková M, et al (2021)

Jekyll or Hyde? The genome (and more) of Nesidiocoris tenuis, a zoophytophagous predatory bug that is both a biological control agent and a pest.

Insect molecular biology, 30(2):188-209.

Nesidiocoris tenuis (Reuter) is an efficient predatory biological control agent used throughout the Mediterranean Basin in tomato crops but regarded as a pest in northern European countries. From the family Miridae, it is an economically important insect yet very little is known in terms of genetic information and no genomic or transcriptomic studies have been published. Here, we use a linked-read sequencing strategy on a single female N. tenuis. From this, we assembled the 355 Mbp genome and delivered an ab initio, homology-based and evidence-based annotation. Along the way, the bacterial "contamination" was removed from the assembly. In addition, bacterial lateral gene transfer (LGT) candidates were detected in the N. tenuis genome. The complete gene set is composed of 24 688 genes; the associated proteins were compared to other hemipterans (Cimex lectularis, Halyomorpha halys and Acyrthosiphon pisum). We visualized the genome using various cytogenetic techniques, such as karyotyping, CGH and GISH, indicating a karyotype of 2n = 32. Additional analyses include the localization of 18S rDNA and unique satellite probes as well as pooled sequencing to assess nucleotide diversity and neutrality of the commercial population. This is one of the first mirid genomes to be released and the first of a mirid biological control agent.

RevDate: 2021-10-21
CmpDate: 2021-10-21

Campanini EB, Pedrino M, Martins LA, et al (2021)

Expression profiles of neotropical termites reveal microbiota-associated, caste-biased genes and biotechnological targets.

Insect molecular biology, 30(2):152-164.

Termites are well recognized by their complex development trajectories, involving dynamic differentiation process between non-reproductive castes, workers and soldiers. These insects are associated with endosymbiotic microorganisms, which help in lignocellulose digestion and nitrogen metabolism. Aiming to identify genes harbouring biotechnological potential, we analyzed workers and soldiers RNA-Seq data of three neotropical termites: Heterotermes tenuis (Isoptera: Rhinotermitidae), Velocitermes heteropterus (Isoptera: Termitidae) and Cornitermes cumulans (Isoptera: Termitidae). We observed differences in the microbiota associated with each termite family, and found protists' genes in both Termitidae species. We found an opposite pattern of caste-biased gene expression between H. tenuis and the termitids studied. Moreover, the two termitids are considerably different concerning the number of differentially expressed genes (DEGs). Functional annotation indicated considerable differences in caste-biased gene content between V. heteropterus and C. cumulans, even though they share similar diet and biological niche. Among the most DEGs, we highlighted those involved in caste differentiation and cellulose digestion, which are attractive targets for studying more efficient technologies for termite control, biomass digestion and other biotechnological applications.

RevDate: 2021-10-21
CmpDate: 2021-10-21

Xia X, Peng CW, Cui JR, et al (2021)

Wolbachia affects reproduction in the spider mite Tetranychus truncatus (Acari: Tetranychidae) by regulating chorion protein S38-like and Rop.

Insect molecular biology, 30(1):18-29.

Wolbachia-induced reproductive regulation in hosts has been used to control pest populations, but little is known about the molecular mechanism underlying Wolbachia regulation of host genes. Here, reproductive regulation by Wolbachia in the spider mite Tetranychus truncatus was studied at the molecular level. Infection with Wolbachia resulted in decreasing oviposition and cytoplasmic incompatibility in T. truncatus. Further RNA-seq revealed genes regulated by Wolbachia in T. truncatus. Real-time quantitative polymerase chain reaction (qPCR) showed that genes, including chorion protein S38-like and Rop were down-regulated by Wolbachia. RNA interference (RNAi) of chorion protein S38-like and Rop in Wolbachia-uninfected T. truncatus decreased oviposition, which was consistent with Wolbachia-induced oviposition decrease. Interestingly, suppressing Rop in Wolbachia-infected T. truncatus led to increased Wolbachia titres in eggs; however, this did not occur after RNAi of chorion protein S38-like. This is the first study to show that chorion protein S38-like and Rop facilitate Wolbachia-mediated changes in T. truncatus fertility. In addition, RNAi of Rop turned the body colour of Wolbachia-uninfected T. truncatus black, which indicates that the role of Rop is not limited to the reproductive regulation of T. truncatus.

RevDate: 2021-10-23

Srinivasan VM, Shlobin NA, Karahalios K, et al (2021)

Adoption of advanced microneurosurgical technologies: an international survey.

World neurosurgery pii:S1878-8750(21)01625-9 [Epub ahead of print].

BACKGROUND: Operating microscopes and adjunctive technologies are continually refined to advance microneurosurgical care. How frequently these advances are used is unknown. This study assesses the international adoption of microneurosurgical technologies and discusses their value.

METHODS: A 27-question electronic survey was distributed to cerebrovascular neurosurgeon members of US, European, and North American neurosurgical societies and to social media networks of cerebrovascular and skull base neurosurgeons. The survey encompassed training background, surgical preferences, and standard microneurosurgical practices.

RESULTS: Among respondents, 56% (53/95) were attendings, 74% (70/95) were in their first 10 years of practice, and 67% (63/94) practiced at an academic teaching hospital. Vascular, endovascular, and skull base fellowships were completed by 38% (36/95), 27% (26/95), and 32% (30/95) of respondents, respectively. Most respondents did not use an exoscope (78%, 73/94), a mouthpiece (61%, 58/95), or foot pedals (56%, 55/94). All 95 used a microscope, and 71 (75%) used Zeiss microscopes. Overall, 57 (60%) neurosurgeons used indocyanine green for aneurysms (n=54), arteriovenous malformations (n=43), and dural arteriovenous fistulas (n=42). Most (80%, 75/94) did not use fluorescence. Participants with a vascular-focused practice more commonly used indocyanine green, Yellow 560 fluorescence, and intraoperative 2-dimensional digital subtraction angiography. Participants with a skull base-focused practice more commonly used foot pedals and an endoscope-assist device.

CONCLUSIONS: This survey characterizes the current adoption of operative microscopes and adjunctive technologies in microneurosurgery. Despite numerous innovations to improve the symbiosis between neurosurgeon and microscope, their adoption is underwhelming. Future advances are essential to improve surgical outcomes.

RevDate: 2021-10-23

Chen H, Wang M, Zhang H, et al (2021)

microRNAs facilitate comprehensive responses of Bathymodiolinae mussel against symbiotic and nonsymbiotic bacteria stimulation.

Fish & shellfish immunology pii:S1050-4648(21)00343-0 [Epub ahead of print].

Bathymodiolinae mussels are dominant species in cold seeps and hydrothermal vents and could harbor endosymbionts in gill bacteriocytes. However, mechanisms underlying the symbiosis have remained largely undisclosed for years. In the present study, the global expression pattern of immune-related genes and miRNAs were surveyed in Gigantidas platifrons during bacterial challenges using enriched symbiotic methane oxidation bacteria MOBs or nonsymbiotic Vibrio. As a result, multiple pattern recognition receptors were found differentially expressed at 12 h and 24 h post bacteria challenges and distinctly clustered between stimulations. Dozens of immune effectors along with signal transducers were also modulated simultaneously during MOB or Vibrio challenge. A total of 459 miRNAs were identified in the gill while some were differentially expressed post MOB or nonsymbiotic bacteria challenge. A variety of immune-related genes were annotated as target genes of aforesaid differentially expressed miRNAs. As a result, biological processes including the immune recognition, lysosome activity and bacteria engulfment were suggested to be dynamically modulated by miRNAs in either symbiotic or nonsymbiotic bacteria challenge. It was suggested that G. platifrons mussels could maintain a robust immune response against invading pathogens while establishing symbiosis with chemosynthetic bacteria with the orchestra of immune-related genes and miRNAs.

RevDate: 2021-10-23

Nouwen N, Chaintreuil C, Fardoux J, et al (2021)

A glutamate synthase mutant of Bradyrhizobium sp. strain ORS285 is unable to induce nodules on Nod factor-independent Aeschynomene species.

Scientific reports, 11(1):20910.

The Bradyrhizobium sp. strain ORS285 is able to establish a nitrogen-fixing symbiosis with both Nod factor (NF) dependent and NF-independent Aeschynomene species. Here, we have studied the growth characteristics and symbiotic interaction of a glutamate synthase (GOGAT; gltD::Tn5) mutant of Bradyrhizobium ORS285. We show that the ORS285 gltD::Tn5 mutant is unable to use ammonium, nitrate and many amino acids as nitrogen source for growth and is unable to fix nitrogen under free-living conditions. Moreover, on several nitrogen sources, the growth rate of the gltB::Tn5 mutant was faster and/or the production of the carotenoid spirilloxanthin was much higher as compared to the wild-type strain. The absence of GOGAT activity has a drastic impact on the symbiotic interaction with NF-independent Aeschynomene species. With these species, inoculation with the ORS285 gltD::Tn5 mutant does not result in the formation of nodules. In contrast, the ORS285 gltD::Tn5 mutant is capable to induce nodules on NF-dependent Aeschynomene species, but these nodules were ineffective for nitrogen fixation. Interestingly, in NF-dependent and NF-independent Aeschynomene species inoculation with the ORS285 gltD::Tn5 mutant results in browning of the plant tissue at the site of the infection suggesting that the mutant bacteria induce plant defence responses.

RevDate: 2021-10-23

Dūmiņš K, Andersone-Ozola U, Samsone I, et al (2021)

Growth and Physiological Performance of a Coastal Species Trifolium fragiferum as Affected by a Coexistence with Trifolium repens, NaCl Treatment and Inoculation with Rhizobia.

Plants (Basel, Switzerland), 10(10): pii:plants10102196.

The aim of the present study was to analyze the growth and physiological performance of two coexisting species, Trifolium fragiferum, and Trifolium repens, under the effect of NaCl and rhizobial symbiosis. Seeds of T. fragiferum and T. repens were collected from populations in the wild, and plants were cultivated in an automated greenhouse, two plants per container. Three basic types of planting were performed: (1) both plants were T. fragiferum (single species), (2) one T. fragiferum and one T. repens (species coexistence), (3) both plants were T. repens (single species). For every basic type, three subtypes were made: (1) non-inoculated, (2) inoculated with rhizobia taken from T. fargiferum, (3) inoculated with rhizobia taken from T. repens. For every subtype, half of the containers were used as control, and half were treated with NaCl. Shoot fresh mass of plants was significantly (p < 0.001) affected by species coexistence, inoculant, and NaCl. Three significant two-way interactions on plant shoot growth were found: between species coexistence and NaCl (p < 0.001), inoculant and species (p < 0.05), and NaCl and species (p < 0.001). A significant three-way interaction between inoculant, NaCl, and species (p < 0.001) indicated different responses of shoot growth of the two species to inoculant type and NaCl. NaCl treatment was an important factor for T. fragiferum, resulting in better growth in conditions of species coexistence, but the positive effect of bacterial inoculant was significantly more pronounced. A decrease in peroxidase activity in leaves was a good indicator of relative NaCl tolerance, while the absence/presence of rhizobial inoculation was reflected by changes in leaf chlorophyll concentration and photochemical activity of photosystem II. It can be concluded that interaction between biotic and abiotic factors affected the outcome of the coexistence of the two Trifolium species. Distribution of T. fragiferum in sea-affected habitats seems to be related to a higher competitive ability with allied species at increased substrate salinity, based on better physiological salinity tolerance.

RevDate: 2021-10-23

Card SD, Bastías DA, JR Caradus (2021)

Antagonism to Plant Pathogens by Epichloë Fungal Endophytes-A Review.

Plants (Basel, Switzerland), 10(10): pii:plants10101997.

Epichloë is a genus of filamentous fungal endophytes that has co-evolved with cool-season grasses with which they form long-term, symbiotic associations. The most agriculturally important associations for pasture persistence for grazing livestock are those between asexual vertically transmitted Epichloë strains and the pasture species, perennial ryegrass, and tall fescue. The fungus confers additional traits to their host grasses including invertebrate pest deterrence and drought tolerance. Selected strains of these mutualistic endophytes have been developed into highly efficacious biocontrol products and are widely utilized within the Americas, Australia, and New Zealand for pasture persistence. Less publicized is the antagonism Epichloë endophytes display towards multiple species of saprophytic and pathogenic microbes. This opinion piece will review the current literature on antimicrobial properties exhibited by this genus of endophyte and discuss the reasons why this trait has historically remained a research curiosity rather than a trait of commercial significance.

RevDate: 2021-10-23

Kameli N, Becker HEF, Welbers T, et al (2021)

Metagenomic Profiling of Fecal-Derived Bacterial Membrane Vesicles in Crohn's Disease Patients.

Cells, 10(10): pii:cells10102795.

BACKGROUND: In the past, many studies suggested a crucial role for dysbiosis of the gut microbiota in the etiology of Crohn's disease (CD). However, despite being important players in host-bacteria interaction, the role of bacterial membrane vesicles (MV) has been largely overlooked in the pathogenesis of CD. In this study, we addressed the composition of the bacterial and MV composition in fecal samples of CD patients and compared this to the composition in healthy individuals.

METHODS: Fecal samples from six healthy subjects (HC) in addition to twelve CD patients (six active, six remission) were analyzed in this study. Fecal bacterial membrane vesicles (fMVs) were isolated by a combination of ultrafiltration and size exclusion chromatography. DNA was obtained from the fMV fraction, the pellet of dissolved feces as bacterial DNA (bDNA), or directly from feces as fecal DNA (fDNA). The fMVs were characterized by nanoparticle tracking analysis and cryo-electron microscopy. Amplicon sequencing of 16s rRNA V4 hypervariable gene regions was conducted to assess microbial composition of all fractions.

RESULTS: Beta-diversity analysis showed that the microbial community structure of the fMVs was significantly different from the microbial profiles of the fDNA and bDNA. However, no differences were observed in microbial composition between fDNA and bDNA. The microbial richness of fMVs was significantly decreased in CD patients compared to HC, and even lower in active patients. Profiling of fDNA and bDNA demonstrated that Firmicutes was the most dominant phylum in these fractions, while in fMVs Bacteroidetes was dominant. In fMV, several families and genera belonging to Firmicutes and Proteobacteria were significantly altered in CD patients when compared to HC.

CONCLUSION: The microbial alterations of MVs in CD patients particularly in Firmicutes and Proteobacteria suggest a possible role of MVs in host-microbe symbiosis and induction or progression of inflammation in CD pathogenesis. Yet, the exact role for these fMV in the pathogenesis of the disease needs to be elucidated in future studies.

RevDate: 2021-10-23

Tanaka Y, Shimizu S, Shirotani M, et al (2021)

Nutrition and Cancer Risk from the Viewpoint of the Intestinal Microbiome.

Nutrients, 13(10): pii:nu13103326.

There are various important factors in reducing the risk of cancer development and progression; these factors may correct an unbalanced intake of nutrients to maintain the living body's homeostasis, detoxify toxic materials, acting as an external factor, and maintain and strengthen the body's immune function. In a normal cell environment, nutrients, such as carbohydrates, lipids, proteins, vitamins, and minerals, are properly digested and absorbed into the body, and, as a result, an environment in which cancer can develop and progress is prevented. It is necessary to prevent toxic materials from entering the body and to detoxify poisons in the body. If these processes occur correctly, cells work normally, and genes cannot be damaged. The most important factor in the fight against cancer and prevention of the development and progression of cancer is the immune system. This requires a nutritional state in which the immune system works well, allowing the intestinal microbiome to carry out all of its roles. In order to grow intestinal microbiota, the consumption of prebiotics, such as organic vegetables, fruits, and dietary fiber, and probiotics of effective intestinal microbiota, such as fermented foods and supplements, is required. Symbiosis, in which these organisms work together, is an effective means of reducing the risk of cancer. In addition, fecal microbiota transplantation (FMT) using ultrafine bubble water, produced specially by the Association for Clinical Research of Fecal Microbiota Transplantation Japan, is also useful for improving the nutritional condition and reducing the risk of cancer.

RevDate: 2021-10-23

Walia AS, Srivastava V, Garg M, et al (2021)

Surface Roughness Analysis of H13 Steel during Electrical Discharge Machining Process Using Cu-TiC Sintered Electrode.

Materials (Basel, Switzerland), 14(20): pii:ma14205943.

In electrical discharge machining (EDM), the machined surface quality can be affected by the excessive temperature generation during the machining process. To achieve a longer life of the finished part, the machined surface quality plays a key role in maintaining its overall integrity. Surface roughness is an important quality evaluation of a material's surface that has considerable influence on mechanical performance of the material. Herein, a sintered cermet tooltip with 75% copper and 25% titanium carbide was used as tool electrode for processing H13 steel. The experiments have been performed to investigate the effects of EDM parameters on the machined surface roughness. The findings show that, as the pulse current, pulse length, and pulse interval are increased, the surface roughness tends to rise. The most significant determinant for surface roughness was found to be pulse current. A semi-empirical surface roughness model was created using the characteristics of the EDM technique. Buckingham's theorem was used to develop a semi-empirical surface roughness prediction model. The semi-empirical model's predictions were in good agreement with the experimental studies, and the built empirical model based on physical features of the cermet tooltip was tested using dimensional analysis.

RevDate: 2021-10-23

Al-Ameeli ZT, Al-Sammak MA, DeLong JP, et al (2021)

Catalysis of Chlorovirus Production by the Foraging of Bursaria truncatella on Paramecia bursaria Containing Endosymbiotic Algae.

Microorganisms, 9(10): pii:microorganisms9102170.

Chloroviruses are large viruses that replicate in chlorella-like green algae and normally exist as mutualistic endosymbionts (referred to as zoochlorellae) in protists such as Paramecium bursaria. Chlorovirus populations rise and fall in indigenous waters through time; however, the factors involved in these virus fluctuations are still under investigation. Chloroviruses attach to the surface of P. bursaria but cannot infect their zoochlorellae hosts because the viruses cannot reach the zoochlorellae as long as they are in the symbiotic phase. Predators of P. bursaria, such as copepods and didinia, can bring chloroviruses into contact with zoochlorellae by disrupting the paramecia, which results in an increase in virus titers in microcosm experiments. Here, we report that another predator of P. bursaria, Bursaria truncatella, can also increase chlorovirus titers. After two days of foraging on P. bursaria, B. truncatella increased infectious chlorovirus abundance about 20 times above the controls. Shorter term foraging (3 h) resulted in a small increase of chlorovirus titers over the controls and more foraging generated more chloroviruses. Considering that B. truncatella does not release viable zoochlorellae either during foraging or through fecal pellets, where zoochlorellae could be infected by chlorovirus, we suggest a third pathway of predator virus catalysis. By engulfing the entire protist and digesting it slowly, virus replication can occur within the predator and some of the virus is passed out through a waste vacuole. These results provide additional support for the hypothesis that predators of P. bursaria are important drivers of chlorovirus population sizes and dynamics.

RevDate: 2021-10-23

Huo D, Li H, Cai F, et al (2021)

Genome Evolution of Filamentous Cyanobacterium Nostoc Species: From Facultative Symbiosis to Free Living.

Microorganisms, 9(10): pii:microorganisms9102015.

In contrast to obligate bacteria, facultative symbiotic bacteria are mainly characterized by genome enlargement. However, the underlying relationship of this feature with adaptations to various habitats remains unclear. In this study, we used the global genome data of Nostoc strains, including 10 novel genomes sequenced in this study and 26 genomes available from public databases, and analyzed their evolutionary history. The evolutionary boundary of the real clade of Nostoc species was identified and was found to be consistent with the results of polyphasic taxonomy. The initial ancestral species of Nostoc was demonstrated to be consistent with a facultative symbiotic population. Further analyses revealed that Nostoc strains tended to shift from facultative symbiosis to a free-living one, along with an increase in genome sizes during the dispersal of each exterior branch. Intracellular symbiosis was proved to be essentially related to Nostoc evolution, and the adaptation of its members to free-living environments was coupled with a large preference for gene acquisition involved in gene repair and recombination. These findings provided unique evidence of genomic mechanisms by which homologous microbes adapt to distinct life manners and external environments.

RevDate: 2021-10-23

Gupta SK, Srivastava M, Osmanoglu Ö, et al (2021)

Aspergillus fumigatus versus Genus Aspergillus: Conservation, Adaptive Evolution and Specific Virulence Genes.

Microorganisms, 9(10): pii:microorganisms9102014.

Aspergillus is an important fungal genus containing economically important species, as well as pathogenic species of animals and plants. Using eighteen fungal species of the genus Aspergillus, we conducted a comprehensive investigation of conserved genes and their evolution. This also allows us to investigate the selection pressure driving the adaptive evolution in the pathogenic species A. fumigatus. Among single-copy orthologs (SCOs) for A. fumigatus and the closely related species A. fischeri, we identified 122 versus 50 positively selected genes (PSGs), respectively. Moreover, twenty conserved genes of unknown function were established to be positively selected and thus important for adaption. A. fumigatus PSGs interacting with human host proteins show over-representation of adaptive, symbiosis-related, immunomodulatory and virulence-related pathways, such as the TGF-β pathway, insulin receptor signaling, IL1 pathway and interfering with phagosomal GTPase signaling. Additionally, among the virulence factor coding genes, secretory and membrane protein-coding genes in multi-copy gene families, 212 genes underwent positive selection and also suggest increased adaptation, such as fungal immune evasion mechanisms (aspf2), siderophore biosynthesis (sidD), fumarylalanine production (sidE), stress tolerance (atfA) and thermotolerance (sodA). These genes presumably contribute to host adaptation strategies. Genes for the biosynthesis of gliotoxin are shared among all the close relatives of A. fumigatus as an ancient defense mechanism. Positive selection plays a crucial role in the adaptive evolution of A. fumigatus. The genome-wide profile of PSGs provides valuable targets for further research on the mechanisms of immune evasion, antimycotic targeting and understanding fundamental virulence processes.

RevDate: 2021-10-23

Landi L, Foglia R, Murolo S, et al (2021)

The Mycorrizal Status in Vineyards Affected by Esca.

Journal of fungi (Basel, Switzerland), 7(10): pii:jof7100869.

In this work we analyzed the relationship among native arbuscular mycorrhizal fungi (AMF) and vine roots affected by esca, a serious grapevine trunk disease. The AMF symbiosis was analyzed on the roots of neighboring plants (symptomatic and asymptomatic to esca) in 14 sites of three vineyards in Marche region (central-eastern Italy). The AMF colonization intensity, identified by non-vital staining, showed higher value in all esca symptomatic plants (ranging from 24.6% to 61.3%) than neighboring asymptomatic plants (from 17.4% to 57.6%). The same trend of Glomeromycota phylum abundance was detected by analyzing fungal operational taxonomic units (OTUs) linked to the AMF community, obtained by amplicon high throughput analysis of ITS 1 region. Overall, the highest amount of OTUs was detected on roots from symptomatic plants (0.42%), compared to asymptomatic roots (0.29%). Specific primer pairs for native Rhizophagus irregularis and Funneliformis mosseae AMF species, were designed in 28S rRNA and large subunit (LSU) ribosomal RNA, respectively, and droplet digital PCR protocol for absolute quantification was set up. A higher number of DNA copies of both fungal species were detected more frequently in symptomatic than asymptomatic vines. Our study suggests a relationship between esca and native AMF in grapevine. These results underline the importance of native rhizosphere microbial communities for a better knowledge of grapevine esca disease.

RevDate: 2021-10-23

Mathur S, Agnihotri R, Sharma MP, et al (2021)

Effect of High-Temperature Stress on Plant Physiological Traits and Mycorrhizal Symbiosis in Maize Plants.

Journal of fungi (Basel, Switzerland), 7(10): pii:jof7100867.

Increasing high temperature (HT) has a deleterious effect on plant growth. Earlier works reported the protective role of arbuscular mycorrhizal fungi (AMF) under stress conditions, particularly influencing the physiological parameters. However, the protective role of AMF under high-temperature stress examining physiological parameters with characteristic phospholipid fatty acids (PLFA) of soil microbial communities including AMF has not been studied. This work aims to study how high-temperature stress affects photosynthetic and below-ground traits in maize plants with and without AMF. Photosynthetic parameters like quantum yield of photosystem (PS) II, PSI, electron transport, and fractions of open reaction centers decreased in HT exposed plants, but recovered in AMF + HT plants. AMF + HT plants had significantly higher AM-signature 16:1ω5cis neutral lipid fatty acid (NLFA), spore density in soil, and root colonization with lower lipid peroxidation than non-mycorrhizal HT plants. As a result, enriched plants had more active living biomass, which improved photosynthetic efficiency when exposed to heat. This study provides an understanding of how AM-mediated plants can tolerate high temperatures while maintaining the stability of their photosynthetic apparatus. This is the first study to combine above- and below-ground traits, which could lead to a new understanding of plant and rhizosphere stress.

RevDate: 2021-10-23

Mayer VE, de Hoog S, Cristescu SM, et al (2021)

Volatile Organic Compounds in the Azteca/Cecropia Ant-Plant Symbiosis and the Role of Black Fungi.

Journal of fungi (Basel, Switzerland), 7(10): pii:jof7100836.

Black fungi of the order Chaetothyriales are grown by many tropical plant-mutualistic ants as small so-called "patches" in their nests, which are located inside hollow structures provided by the host plant ("domatia"). These fungi are introduced and fostered by the ants, indicating that they are important for the colony. As several species of Chaetothyriales tolerate, adsorb, and metabolize toxic volatiles, we investigated the composition of volatile organic compounds (VOCs) of selected domatia in the Azteca/Cecropia ant-plant mutualism. Concentrations of VOCs in ant-inhabited domatia, empty domatia, and background air were compared. In total, 211 compounds belonging to 19 chemical families were identified. Ant-inhabited domatia were dominated by ketones with 2-heptanone, a well-known ant alarm semiochemical, as the most abundant volatile. Empty domatia were characterized by relatively high concentrations of the monoterpenes d-limonene, p-cymene and β-phellandrene, as well as the heterocyclic sulphur-containing compound, benzothiazole. These compounds have biocidal properties and are primarily biosynthesized by plants as a defense mechanism. Interestingly, most of the latter compounds were present at lower concentrations in ant inhabited domatia than in non-colonized ones. We suggest that Chaetothyriales may play a role in reducing the VOCs, underlining that the mutualistic nature of these fungi as VOCs accumulation might be detrimental for the ants, especially the larvae.

RevDate: 2021-10-23

Muñoz-Benavent M, Latorre A, Alemany-Cosme E, et al (2021)

Gut Microbiota Cannot Compensate the Impact of (quasi) Aposymbiosis in Blattella germanica.

Biology, 10(10): pii:biology10101013.

Blattella germanica presents a very complex symbiotic system, involving the following two kinds of symbionts: the endosymbiont Blattabacterium and the gut microbiota. Although the role of the endosymbiont has been fully elucidated, the function of the gut microbiota remains unclear. The study of the gut microbiota will benefit from the availability of insects deprived of Blattabacterium. Our goal is to determine the effect of the removal (or, at least, the reduction) of the endosymbiont population on the cockroach's fitness, in a normal gut microbiota community. For this purpose, we treated our cockroach population, over several generations, with rifampicin, an antibiotic that only affects the endosymbiont during its extracellular phase, and decreases its amount in the following generation. As rifampicin also affects gut bacteria that are sensitive to this antibiotic, the treatment was performed during the first 12 days of the adult stage, which is the period when the endosymbiont infects the oocytes and lacks bacteriocyte protection. We found that after this antibiotic treatment, the endosymbiont population remained extremely reduced and only the microbiota was able to recover, although it could not compensate for the endosymbiont role, and the host's fitness was drastically affected. This accomplished reduction, however, is not homogenous and requires further study to develop stable quasi-aposymbiotic cockroaches.

RevDate: 2021-10-23

Gojda J, M Cahova (2021)

Gut Microbiota as the Link between Elevated BCAA Serum Levels and Insulin Resistance.

Biomolecules, 11(10): pii:biom11101414.

The microbiota-harboring human gut is an exquisitely active ecosystem that has evolved in a constant symbiosis with the human host. It produces numerous compounds depending on its metabolic capacity and substrates availability. Diet is the major source of the substrates that are metabolized to end-products, further serving as signal molecules in the microbiota-host cross-talk. Among these signal molecules, branched-chain amino acids (BCAAs) has gained significant scientific attention. BCAAs are abundant in animal-based dietary sources; they are both produced and degraded by gut microbiota and the host circulating levels are associated with the risk of type 2 diabetes. This review aims to summarize the current knowledge on the complex relationship between gut microbiota and its functional capacity to handle BCAAs as well as the host BCAA metabolism in insulin resistance development. Targeting gut microbiota BCAA metabolism with a dietary modulation could represent a promising approach in the prevention and treatment of insulin resistance related states, such as obesity and diabetes.

RevDate: 2021-10-23

Krohn I, Bergmann L, Qi M, et al (2021)

Deep (Meta)genomics and (Meta)transcriptome Analyses of Fungal and Bacteria Consortia From Aircraft Tanks and Kerosene Identify Key Genes in Fuel and Tank Corrosion.

Frontiers in microbiology, 12:722259.

Microbial contamination of fuels, associated with a wide variety of bacteria and fungi, leads to decreased product quality and can compromise equipment performance by biofouling or microbiologically influenced corrosion. Detection and quantification of microorganisms are critical in monitoring fuel systems for an early detection of microbial contaminations. To address these challenges, we have analyzed six metagenomes, one transcriptome, and more than 1,200 fluid and swab samples taken from fuel tanks or kerosene. Our deep metagenome sequencing and binning approaches in combination with RNA-seq data and qPCR methods implied a metabolic symbiosis between fungi and bacteria. The most abundant bacteria were affiliated with α-, β-, and γ-Proteobacteria and the filamentous fungi Amorphotheca. We identified a high number of genes, which are related to kerosene degradation and biofilm formation. Surprisingly, a large number of genes coded enzymes involved in polymer degradation and potential bio-corrosion processes. Thereby, the transcriptionally most active microorganisms were affiliated with the genera Methylobacteria, Pseudomonas, Kocuria, Amorpotheka, Aspergillus, Fusarium, and Penicillium. Many not yet cultured bacteria and fungi appeared to contribute to the biofilm transcriptional activities. The largest numbers of transcripts were observed for dehydrogenase, oxygenase, and exopolysaccharide production, attachment and pili/flagella-associated proteins, efflux pumps, and secretion systems as well as lipase and esterase activity.

RevDate: 2021-10-23
CmpDate: 2021-10-21

Avila-Magaña V, Kamel B, DeSalvo M, et al (2021)

Elucidating gene expression adaptation of phylogenetically divergent coral holobionts under heat stress.

Nature communications, 12(1):5731.

As coral reefs struggle to survive under climate change, it is crucial to know whether they have the capacity to withstand changing conditions, particularly increasing seawater temperatures. Thermal tolerance requires the integrative response of the different components of the coral holobiont (coral host, algal photosymbiont, and associated microbiome). Here, using a controlled thermal stress experiment across three divergent Caribbean coral species, we attempt to dissect holobiont member metatranscriptome responses from coral taxa with different sensitivities to heat stress and use phylogenetic ANOVA to study the evolution of gene expression adaptation. We show that coral response to heat stress is a complex trait derived from multiple interactions among holobiont members. We identify host and photosymbiont genes that exhibit lineage-specific expression level adaptation and uncover potential roles for bacterial associates in supplementing the metabolic needs of the coral-photosymbiont duo during heat stress. Our results stress the importance of integrative and comparative approaches across a wide range of species to better understand coral survival under the predicted rise in sea surface temperatures.

RevDate: 2021-10-20

Bhalla S, N Garg (2021)

Arbuscular mycorrhizae and silicon alleviate arsenic toxicity by enhancing soil nutrient availability, starch degradation and productivity in Cajanus cajan (L.) Millsp.

Mycorrhiza [Epub ahead of print].

Arsenic (As) pollution of soil reduces the growth and reproductive potential of plants. Silicon (Si) and arbuscular mycorrhizal (AM) fungi play significant roles in alleviating adverse effects of As stress. However, studies are scant regarding alleviative effects of Si in pigeonpea (Cajanus cajan L. Millsp.) because legumes are considered low Si-accumulators. We investigated the individual as well as synergistic potential of Si with two AM species (M1-Claroideoglomus etunicatum and M2-Rhizoglomus intraradices) in modulating soil properties, thereby improving growth and productivity of pigeonpea genotype Pusa 2001 grown in AsV and AsIII challenged soils. Both As species hampered the establishment of AM symbiosis, thus, reducing nutrient uptake, growth and yield, with AsIII more toxic than AsV. Exogenously applied Si and AM species enhanced soil glomalin and phosphatases activity, hence decreased metal bioavailability in soil, increased plant nutrient acquisition, biomass and chlorophylls; with maximum benefits provided by M2, closely followed by Si and least by M1. These amendments boosted the activities of starch hydrolytic enzymes (α-, β-amylase, starch phosphorylase) in plants, along with a simultaneous increase in total soluble sugars (TSS). This enhanced sugar accumulation directly led to improved reproductive attributes, more efficiently by M2 and Si than by M1. Moreover, there was a substantial increase in proline biosynthesis due to significantly enhanced activities of its biosynthetic enzymes. Additionally, combined applications of Si and AM, especially +Si+M2, complemented each other where AM enhanced Si uptake, while Si induced mycorrhization, suggesting their mutual and beneficial roles in ameliorating metal(loid) toxicity and achieving sustainability in pigeonpea production under As stress.

RevDate: 2021-10-20

Yoshikawa A, Nakazawa S, A Asakura (2019)

A Brief Description of Surface Structure and Composition of the Pseudo-Snail Shell Formed by a Sea Anemone Stylobates sp. Symbiotic with Hermit Crabs from the Deep-Sea Floor.

Zoological science, 36(4):284-293.

Sea anemones belonging to the genera Adamsia and Stylobates have a remarkable symbiotic relationship with hermit crabs. These symbiotic sea anemones produce a shell-like structure, called a "carcinoecium," that covers and extends over the gastropod shell of the host hermit crab as hermit crabs grow. This structure has been described as "chitinous carcinoecium" or "chitinous coating." A previous study investigated carcinoecia of Stylobates aeneus, the results of which indicated that it contained at least 1.7% chitin, while the remaining components were unidentified. Moreover, the microscopic structure of a carcinoecium still remains to be detailed. We, therefore, conducted detailed observations using a stereoscopic microscope and scanning electron microscope (SEM) and the analyses of the chemical composition of carcinoecia produced by Stylobates sp. (apparently conspecific with Isadamsia sp. "J" reported in Uchida and Soyama, 2001) associated with a pagurid hermit crab Pagurodofleinia doederleini collected in the south of the Shima Peninsula, Mie, Honshu Island, Japan at a depth of 294-306 m. Our results indicate that carcinoecia of Stylobates sp. contain HCl-soluble components (13%), NaOH-soluble components (38%), chitin (11%) and unidentified remnants (39%). Additionally, our observations show that Stylobates sp. incorporates dark- and white-colored particles that could be sand and/or mud into the carcinoecium.

RevDate: 2021-10-18

Tang CC, Zhang XY, Wang R, et al (2021)

Calcium ions-effect on performance, growth and extracellular nature of microalgal-bacterial symbiosis system treating wastewater.

Environmental research pii:S0013-9351(21)01529-2 [Epub ahead of print].

Microalgal-bacterial symbiosis (MABS) system treating wastewater has attracted great concern because of its advantages of carbon dioxide reduction and biomass energy production. However, due to the low density and negative surface charge of microalgae cells, the sedimentation and harvesting performance of microalgae biomass has been one limitation for the application of MABS system on wastewater treatment. This study investigated the performance enhancement of microalgae harvesting and wastewater treatment contributed by calcium ions (i.e., Ca2+) in the MABS system. Results showed that a low Ca2+ loading (i.e., 0.1 mM) promoted both COD and nutrients removal, with growth rates of 11.95, 6.53 and 1.21% for COD, TN and TP compared to control, and chlorophyll a was increased by 64.15%. Differently, a high Ca2+ loading (i.e., 10 mM) caused removal reductions by improving the aggregation of microalgae, with reduction rates of 34.82, 3.50 and 10.30% for COD, NH4+-N and TP. Mechanism analysis indicated that redundant Ca2+ adsorbed on MABS aggregates and dissolved in wastewater decreased the dispersibility of microalgae cells by electrical neutralization and compressed double electric layer. Moreover, the presence of Ca2+ could improve extracellular secretions and promoted flocculation performance, with particle size increasing by 336.22%. The findings of this study may provide some solutions for the enhanced microalgae biomass harvest and nutrients removal from wastewater.

RevDate: 2021-10-18

Znój A, Gawor J, Gromadka R, et al (2021)

Root-Associated Bacteria Community Characteristics of Antarctic Plants: Deschampsia antarctica and Colobanthus quitensis-a Comparison.

Microbial ecology [Epub ahead of print].

Colobanthus quitensis (Kunth) Bartl. and Deschampsia antarctica Desv. are the only Magnoliophyta to naturally colonize the Antarctic region. The reason for their sole presence in Antarctica is still debated as there is no definitive consensus on how only two unrelated flowering plants managed to establish breeding populations in this part of the world. In this study, we have explored and compared the rhizosphere and root-endosphere dwelling microbial community of C. quitensis and D. antarctica specimens sampled in maritime Antarctica from sites displaying contrasting edaphic characteristics. Bacterial phylogenetic diversity (high-throughput 16S rRNA gene fragment targeted sequencing) and microbial metabolic activity (Biolog EcoPlates) with a geochemical soil background were assessed. Gathered data showed that the microbiome of C. quitensis root system was mostly site-dependent, displaying different characteristics in each of the examined locations. This plant tolerated an active bacterial community only in severe conditions (salt stress and nutrient deprivation), while in other more favorable circumstances, it restricted microbial activity, with a possibility of microbivory-based nutrient acquisition. The microbial communities of D. antarctica showed a high degree of similarity between samples within a particular rhizocompartment. The grass' endosphere was significantly enriched in plant beneficial taxa of the family Rhizobiaceae, which displayed obligatory endophyte characteristics, suggesting that at least part of this community is transmitted vertically. Ultimately, the ecological success of C. quitensis and D. antarctica in Antarctica might be largely attributed to their associations and management of root-associated microbiota.

RevDate: 2021-10-18

Cai XW, Bao YQ, Hu MF, et al (2021)

Simulation and Prediction of Fungal Community Evolution Based on RBF Neural Network.

Computational and mathematical methods in medicine, 2021:7918192.

Simulation and prediction of the scale change of fungal community. First, using the experimental data of a variety of fungal decomposition activities, a mathematical model of the decomposition rate and the relationship between the bacterial species was established, thereby revealing the internal mechanism of fungal decomposition activity in a complex environment. Second, based on the linear regression method and the principle of biodiversity, a model of fungal decomposition rate was constructed, and it was concluded that the interaction between mycelial elongation and moisture resistance could increase the fungal decomposition rate. Third, the differential equations are used to quantify the competitive relationship between different bacterial species, divide the boundaries of superior and inferior species, and simulate the long-term and short-term evolution trends of the community under the same initial environment. And an empirical analysis is made by taking the sudden change of the atmosphere affecting the evolution of the colony as an example. Finally, starting from summer, combining soil temperature, humidity, and fungal species data in five different environments such as arid and semiarid, a three-dimensional model and RBF neural network are introduced to predict community evolution. The study concluded that under given conditions, different strains are in short-term competition, and in the long-term, mutually beneficial symbiosis. Biodiversity is important for the biological regulation of nature.

RevDate: 2021-10-18

Li J, Chen L, Li D, et al (2021)

Electroacupuncture Promotes the Survival of the Grafted Human MGE Neural Progenitors in Rats with Cerebral Ischemia by Promoting Angiogenesis and Inhibiting Inflammation.

Neural plasticity, 2021:4894881.

Stem cells have the potential as a regenerative therapy for cerebral ischemia by improving functional outcomes. However, cell transplantation has some limitations, including a low rate of the grafted cell survival. There is still a major challenge of promoting the harmonious symbiosis between grafted cells and the host. Acupuncture can effectively improve the functional outcome after cerebral ischemia. The present study evaluated the therapeutic effects and explored the mechanism of combined medial ganglionic eminence (MGE) neural progenitors differentiated from human embryonic stem cells (hESCs) with electroacupuncture (EA) in a bilateral common carotid artery occlusion (2VO) rat model. The results showed that EA could promote the survival of the grafted MGE neural progenitors differentiated from hESCs and alleviate learning and memory impairment in rats with cerebral ischemia. This may have partially resulted from inhibited expression of TNF-α and IL-1β and increased vascular endothelial growth factor (VEGF) expression and blood vessel density in the hippocampus. Our findings indicated that EA could promote the survival of the grafted MGE neural progenitors and enhance transplantation therapy's efficacy by promoting angiogenesis and inhibiting inflammation.

RevDate: 2021-10-19
CmpDate: 2021-10-19

Walambe R, Marathe A, Kotecha K, et al (2021)

Lightweight Object Detection Ensemble Framework for Autonomous Vehicles in Challenging Weather Conditions.

Computational intelligence and neuroscience, 2021:5278820.

The computer vision systems driving autonomous vehicles are judged by their ability to detect objects and obstacles in the vicinity of the vehicle in diverse environments. Enhancing this ability of a self-driving car to distinguish between the elements of its environment under adverse conditions is an important challenge in computer vision. For example, poor weather conditions like fog and rain lead to image corruption which can cause a drastic drop in object detection (OD) performance. The primary navigation of autonomous vehicles depends on the effectiveness of the image processing techniques applied to the data collected from various visual sensors. Therefore, it is essential to develop the capability to detect objects like vehicles and pedestrians under challenging conditions such as like unpleasant weather. Ensembling multiple baseline deep learning models under different voting strategies for object detection and utilizing data augmentation to boost the models' performance is proposed to solve this problem. The data augmentation technique is particularly useful and works with limited training data for OD applications. Furthermore, using the baseline models significantly speeds up the OD process as compared to the custom models due to transfer learning. Therefore, the ensembling approach can be highly effective in resource-constrained devices deployed for autonomous vehicles in uncertain weather conditions. The applied techniques demonstrated an increase in accuracy over the baseline models and were able to identify objects from the images captured in the adverse foggy and rainy weather conditions. The applied techniques demonstrated an increase in accuracy over the baseline models and reached 32.75% mean average precision (mAP) and 52.56% average precision (AP) in detecting cars in the adverse fog and rain weather conditions present in the dataset. The effectiveness of multiple voting strategies for bounding box predictions on the dataset is also demonstrated. These strategies help increase the explainability of object detection in autonomous systems and improve the performance of the ensemble techniques over the baseline models.

RevDate: 2021-10-18

Loh XK, Lee VH, Loh XM, et al (2021)

The Dark Side of Mobile Learning via Social Media: How Bad Can It Get?.

Information systems frontiers : a journal of research and innovation pii:10202 [Epub ahead of print].

As the COVID-19 pandemic continues to spread at an unprecedented rate, many universities around the world halted physical forms of teaching and learning to stop the spread of the virus. As a result, many university students were forced to utilize online learning through channels such as mobile social media. Due to the novelty of this situation, there are many unknowns particularly with the negative influences of mobile learning via social media on university students. Thus, this study looks to examine this subject matter from the perspective of the stimulus-organism-response theory. The uniquely developed research model included four stimuli (i.e., social overload, information overload, life invasion, and privacy invasion), two organisms (i.e., technostress and exhaustion) as well as a response in terms of reduced intention to use mobile learning via social media. The responses were collected from 384 university students via an online survey and analyzed with the Partial-Least-Square-Structural-Equation-Modelling. It was found that the antecedents for both technostress and exhaustion were able to account for more than half of their respective variances. Furthermore, technostress and exhaustion were significant facilitators of the students' reduced intention to use mobile learning via social media. In addition to the practical insights for stakeholders in the education industry, this study also posited several theoretical implications for researchers.

RevDate: 2021-10-19
CmpDate: 2021-10-19

Cao BF, Jiang HX, Liu L, et al (2021)

[Research progress on mechanism of arbuscular common mycorrhizal networks in plant-plant interactions].

Ying yong sheng tai xue bao = The journal of applied ecology, 32(9):3385-3396.

Plant-plant interactions is one of the key field in ecology, which is important for the efficient nutrient utilization, productivity improvement, and plant community assembly. Arbuscular mycorrhizal fungi are important plant mutualistic microorganisms that connect plant roots to form common mycelial networks (CMNs), which play major roles in transferring nutrients and water and regu-lating plant community dynamics. Recent studies demonstrated that these CMNs could act as conduits for transmitting disease and aphid-induced signals among plants, and activating chemical defence in uninfested neighboring plants. In this review, we introduced recent research advances on the contribution of CMNs on plant interaction, the main factors that influences the functions of CMNs, and the role of CMNs transfer and redistribute nutrients and water among plant. In addition, the mechanism underlying underground chemical signal communication, seedling establishment and plants community assembly were summarized. Finally, we proposed challenges facing CMNs in plant-plant interactions and the practical problems. It would provide reference for further understanding the ecological functions of CMNs in plant-plant interactions.

RevDate: 2021-10-17

Antoine S, Hériché M, Boussageon R, et al (2021)

A historical perspective on mycorrhizal mutualism emphasizing arbuscular mycorrhizas and their emerging challenges.

Mycorrhiza [Epub ahead of print].

Arbuscular mycorrhiza, one of the oldest interactions on earth (~ 450 million years old) and a first-class partner for plants to colonize emerged land, is considered one of the most pervasive ecological relationships on the globe. Despite how important and old this interaction is, its discovery was very recent compared to the long story of land plant evolution. The story of the arbuscular mycorrhiza cannot be addressed apart from the history, controversies, and speculations about mycorrhiza in its broad sense. The chronicle of mycorrhizal research is marked by multiple key milestones such as the initial description of a "persistent epiderm and pellicular wall structure" by Hartig; the introduction of the "Symbiotismus" and "Mycorrhiza" concepts by Frank; the description of diverse root-fungal morphologies; the first description of arbuscules by Gallaud; Mosse's pivotal statement of the beneficial nature of the arbuscular mycorrhizal symbiosis; the impact of molecular tools on the taxonomy of mycorrhizal fungi as well as the development of in vitro root organ cultures for producing axenic arbuscular mycorrhizal fungi (AMF). An appreciation of the story - full of twists and turns - of the arbuscular mycorrhiza, going from the roots of mycorrhiza history, along with the discovery of different mycorrhiza types such as ectomycorrhiza, can improve research to help face our days' challenge of developing sustainable agriculture that integrates the arbuscular mycorrhiza and its ecosystem services.

RevDate: 2021-10-18
CmpDate: 2021-10-18

Wang T, Guo J, Peng Y, et al (2021)

Light-induced mobile factors from shoots regulate rhizobium-triggered soybean root nodulation.

Science (New York, N.Y.), 374(6563):65-71.

[Figure: see text].

RevDate: 2021-10-19
CmpDate: 2021-10-19

Koosha RZ, Fazel P, Sedighian H, et al (2021)

The impact of the gut microbiome on toxigenic bacteria.

Microbial pathogenesis, 160:105188.

Millions of symbiotic and pathogenic microorganisms known as microbiota colonize the host body. The microbiome plays an important role in human health and colonizes hundreds of different species of multicellular organisms so that they are introduced as the metaorganisms. Changes in the microbial population of the gut microbiome may cause resistance to pathogenic bacteria-induced infection. Understanding the principles of Host-Microbiota Interactions (HMIs) is important because it clarifies our insight towards the mechanisms of infections established in the host. Interactions between the host and the microbiota help answer the question of how a microorganism can contribute to the health or disease of the host. Microbiota can increase host resistance to colonization of pathogenic species. Studying the HMIs network can in several ways delineate the pathogenic mechanisms of pathogens and thereby help to increase useful and novel therapeutic pathways. For example, the potentially unique microbial effects that target the distinct host or interfere with the endogenous host interactions can be identified. In addition, the way mutations in essential proteins in the host and/or in the microbes can influence the interactions between them may be determined. Furthermore, HMIs help in identifying host cell regulatory modules.

RevDate: 2021-10-19
CmpDate: 2021-10-19

Salazar MM, Pupo MT, AMV Brown (2021)

Co-Occurrence of Viruses, Plant Pathogens, and Symbionts in an Underexplored Hemipteran Clade.

Frontiers in cellular and infection microbiology, 11:715998.

Interactions between insect symbionts and plant pathogens are dynamic and complex, sometimes involving direct antagonism or synergy and sometimes involving ecological and evolutionary leaps, as insect symbionts transmit through plant tissues or plant pathogens transition to become insect symbionts. Hemipterans such as aphids, whiteflies, psyllids, leafhoppers, and planthoppers are well-studied plant pests that host diverse symbionts and vector plant pathogens. The related hemipteran treehoppers (family Membracidae) are less well-studied but offer a potentially new and diverse array of symbionts and plant pathogenic interactions through their distinct woody plant hosts and ecological interactions with diverse tending hymenopteran taxa. To explore membracid symbiont-pathogen diversity and co-occurrence, this study performed shotgun metagenomic sequencing on 20 samples (16 species) of treehopper, and characterized putative symbionts and pathogens using a combination of rapid blast database searches and phylogenetic analysis of assembled scaffolds and correlation analysis. Among the 8.7 billion base pairs of scaffolds assembled were matches to 9 potential plant pathogens, 12 potential primary and secondary insect endosymbionts, numerous bacteriophages, and other viruses, entomopathogens, and fungi. Notable discoveries include a divergent Brenneria plant pathogen-like organism, several bee-like Bombella and Asaia strains, novel strains of Arsenophonus-like and Sodalis-like symbionts, Ralstonia sp. and Ralstonia-type phages, Serratia sp., and APSE-type phages and bracoviruses. There were several short Phytoplasma and Spiroplasma matches, but there was no indication of plant viruses in these data. Clusters of positively correlated microbes such as yeast-like symbionts and Ralstonia, viruses and Serratia, and APSE phage with parasitoid-type bracoviruses suggest directions for future analyses. Together, results indicate membracids offer a rich palette for future study of symbiont-plant pathogen interactions.

RevDate: 2021-10-18
CmpDate: 2021-10-18

Inderjit , Simberloff D, Kaur H, et al (2021)

Novel chemicals engender myriad invasion mechanisms.

The New phytologist, 232(3):1184-1200.

Non-native invasive species (NIS) release chemicals into the environment that are unique to the invaded communities, defined as novel chemicals. Novel chemicals impact competitors, soil microbial communities, mutualists, plant enemies, and soil nutrients differently than in the species' native range. Ecological functions of novel chemicals and differences in functions between the native and non-native ranges of NIS are of immense interest to ecologists. Novel chemicals can mediate different ecological, physiological, and evolutionary mechanisms underlying invasion hypotheses. Interactions amongst the NIS and resident species including competitors, soil microbes, and plant enemies, as well as abiotic factors in the invaded community are linked to novel chemicals. However, we poorly understand how these interactions might enhance NIS performance. New empirical data and analyses of how novel chemicals act in the invaded community will fill major gaps in our understanding of the chemistry of biological invasions. A novel chemical-invasion mechanism framework shows how novel chemicals engender invasion mechanisms beyond plant-plant or plant-microorganism interactions.

RevDate: 2021-10-20
CmpDate: 2021-10-20

von Beeren C, Blüthgen N, Hoenle PO, et al (2021)

A remarkable legion of guests: Diversity and host specificity of army ant symbionts.

Molecular ecology, 30(20):5229-5246.

Tropical rainforests are among the most diverse biomes on Earth. While species inventories are far from complete for any tropical rainforest, even less is known about the intricate species interactions that form the basis of these ecological communities. One fascinating but poorly studied example are the symbiotic associations between army ants and their rich assemblages of parasitic arthropod guests. Hundreds of these guests, or myrmecophiles, have been taxonomically described. However, because previous work has mainly been based on haphazard collections from disjunct populations, it remains challenging to define species boundaries. We therefore know little about the species richness, abundance and host specificity of most guests in any given population, which is crucial to understand co-evolutionary and ecological dynamics. Here, we report a quantitative community survey of myrmecophiles parasitizing the six sympatric Eciton army ant species in a Costa Rican rainforest. Combining DNA barcoding with morphological identification of over 2,000 specimens, we discovered 62 species, including 49 beetles, 11 flies, one millipede and one silverfish. At least 14 of these species were new to science. Ecological network analysis revealed a clear signal of host partitioning, and each Eciton species was host to both specialists and generalists. These varying degrees in host specificities translated into a moderate level of network specificity, highlighting the system's level of biotic pluralism in terms of biodiversity and interaction diversity. By providing vouchered DNA barcodes for army ant guest species, this study provides a baseline for future work on co-evolutionary and ecological dynamics in these species-rich host-symbiont networks across the Neotropical realm.

RevDate: 2021-10-19
CmpDate: 2021-10-19

Cornwell B, Armstrong K, Walker NS, et al (2021)

Widespread variation in heat tolerance and symbiont load are associated with growth tradeoffs in the coral Acropora hyacinthus in Palau.

eLife, 10:.

Climate change is dramatically changing ecosystem composition and productivity, leading scientists to consider the best approaches to map natural resistance and foster ecosystem resilience in the face of these changes. Here, we present results from a large-scale experimental assessment of coral bleaching resistance, a critical trait for coral population persistence as oceans warm, in 221 colonies of the coral Acropora hyacinthus across 37 reefs in Palau. We find that bleaching-resistant individuals inhabit most reefs but are found more often in warmer microhabitats. Our survey also found wide variation in symbiont concentration among colonies, and that colonies with lower symbiont load tended to be more bleaching-resistant. By contrast, our data show that low symbiont load comes at the cost of lower growth rate, a tradeoff that may operate widely among corals across environments. Corals with high bleaching resistance have been suggested as a source for habitat restoration or selective breeding in order to increase coral reef resilience to climate change. Our maps show where these resistant corals can be found, but the existence of tradeoffs with heat resistance may suggest caution in unilateral use of this one trait in restoration.

RevDate: 2021-10-20
CmpDate: 2021-10-20

Voolstra CR, Valenzuela JJ, Turkarslan S, et al (2021)

Contrasting heat stress response patterns of coral holobionts across the Red Sea suggest distinct mechanisms of thermal tolerance.

Molecular ecology, 30(18):4466-4480.

Corals from the northern Red Sea, in particular the Gulf of Aqaba (GoA), have exceptionally high bleaching thresholds approaching >5℃ above their maximum monthly mean (MMM) temperatures. These elevated thresholds are thought to be due to historical selection, as corals passed through the warmer Southern Red Sea during recolonization from the Arabian Sea. To test this hypothesis, we determined thermal tolerance thresholds of GoA versus central Red Sea (CRS) Stylophora pistillata corals using multi-temperature acute thermal stress assays to determine thermal thresholds. Relative thermal thresholds of GoA and CRS corals were indeed similar and exceptionally high (~7℃ above MMM). However, absolute thermal thresholds of CRS corals were on average 3℃ above those of GoA corals. To explore the molecular underpinnings, we determined gene expression and microbiome response of the coral holobiont. Transcriptomic responses differed markedly, with a strong response to the thermal stress in GoA corals and their symbiotic algae versus a remarkably muted response in CRS colonies. Concomitant to this, coral and algal genes showed temperature-induced expression in GoA corals, while exhibiting fixed high expression (front-loading) in CRS corals. Bacterial community composition of GoA corals changed dramatically under heat stress, whereas CRS corals displayed stable assemblages. We interpret the response of GoA corals as that of a resilient population approaching a tipping point in contrast to a pattern of consistently elevated thermal resistance in CRS corals that cannot further attune. Such response differences suggest distinct thermal tolerance mechanisms that may affect the response of coral populations to ocean warming.

RevDate: 2021-10-19
CmpDate: 2021-10-19

Granjon L, Fossati-Gaschignard O, Artige E, et al (2021)

Commensal small mammal trapping data in Southern Senegal, 2012-2015: where invasive species meet native ones.

Ecology, 102(10):e03470.

Describing patterns and testing hypotheses on processes driving biological invasions represent major issues in ecology. Addressing these questions requires building adequate data sets, i.e., covering areas and spanning periods adapted to the invasion processes studied. Rodents include major invasive species, among which the black rat Rattus rattus and the domestic mouse Mus musculus have nearly colonized the entire world, from their native Asian range. To do so, they have benefitted from their ability to cope with human-modified environments and to live in the immediate vicinity of Man, who served as a vector of their dispersal between regions and continents. In Senegal, both R. rattus and M. musculus, initially introduced by early West European colonizers some centuries ago, are currently expanding thanks to road traffic and infrastructure development and rampant urbanization that concerns even remote regions of the country. As part of projects aimed at studying (1) the role of invasive black rat populations in the emergence of zoonotic diseases in southeastern Senegal, and (2) the evolutionary consequences of parasites in R. rattus and M. musculus invasions in Senegal, we conducted a series of field campaigns throughout the southern half of the country, between May 2012 and September 2015. The objectives were to catch commensal small mammals using standard trapping procedures, identify them using morphological or molecular tools, and take samples from them upon autopsy, to look for zoonotic parasites and pathogens. Along with data on individual specimens, information on microhabitats was gathered at each trap position. This resulted in the constitution of a data set of more than 13,000 trapnights, which allowed the capture of more than 3,100 small mammals, all characterized by a series of associated biological, geographical, and environmental data. The small mammals concerned are mainly rodents (10 species), shrews, and hedgehogs. The two invasive rodent species were the most numerous, exceeding in numbers all the other species pooled. This data set makes it possible to study coarse to fine-scaled distribution of species of this commensal community in southern Senegal, as well as the possible determinants of this distribution in terms of habitat preferences and/or interspecific interactions. This data set can be freely used for non-commercial purposes and is licensed under a Creative Commons Attribution 4.0 International License.

RevDate: 2021-10-20
CmpDate: 2021-10-20

Hoadley KD, Pettay DT, Lewis A, et al (2021)

Different functional traits among closely related algal symbionts dictate stress endurance for vital Indo-Pacific reef-building corals.

Global change biology, 27(20):5295-5309.

Reef-building corals in the genus Porites are one of the most important constituents of Indo-Pacific reefs. Many species within this genus tolerate abnormally warm water and exhibit high specificity for particular kinds of endosymbiotic dinoflagellates that cope with thermal stress better than those living in other corals. Still, during extreme ocean heating, some Porites exhibit differences in their stress tolerance. While corals have different physiological qualities, it remains unknown whether the stability and performance of these mutualisms is influenced by the physiology and genetic relatedness of their symbionts. We investigated two ubiquitous Pacific reef corals, Porites rus and Porites cylindrica, from warmer inshore and cooler offshore reef systems in Palau. While these corals harbored a similar kind of symbiont in the genus Cladocopium (within the ITS2 C15 subclade), rapidly evolving genetic markers revealed evolutionarily diverged lineages corresponding to each Porites species living in each reef habitat. Furthermore, these closely related Cladocopium lineages were differentiated by their densities in host tissues, cell volume, chlorophyll concentration, gross photosynthesis, and photoprotective pathways. When assessed using several physiological proxies, these previously undifferentiated symbionts contrasted in their tolerance to thermal stress. Symbionts within P. cylindrica were relatively unaffected by exposure to 32℃ for 14 days, whereas P. rus colonies lost substantial numbers of photochemically compromised symbionts. Heating reduced the ability of the offshore symbiont associated with P. rus to translocate carbon to the coral. By contrast, high temperatures enhanced symbiont carbon assimilation and delivery to the coral skeleton of inshore P. cylindrica. This study indicates that large physiological differences exist even among closely related symbionts, with significant implications for thermal susceptibility among reef-building Porites.

RevDate: 2021-10-18
CmpDate: 2021-10-18

Yamagishi JF, Saito N, K Kaneko (2021)

Adaptation of metabolite leakiness leads to symbiotic chemical exchange and to a resilient microbial ecosystem.

PLoS computational biology, 17(6):e1009143.

Microbial communities display remarkable diversity, facilitated by the secretion of chemicals that can create new niches. However, it is unclear why cells often secrete even essential metabolites after evolution. Based on theoretical results indicating that cells can enhance their own growth rate by leaking even essential metabolites, we show that such "leaker" cells can establish an asymmetric form of mutualism with "consumer" cells that consume the leaked chemicals: the consumer cells benefit from the uptake of the secreted metabolites, while the leaker cells also benefit from such consumption, as it reduces the metabolite accumulation in the environment and thereby enables further secretion, resulting in frequency-dependent coexistence of multiple microbial species. As supported by extensive simulations, such symbiotic relationships generally evolve when each species has a complex reaction network and adapts its leakiness to optimize its own growth rate under crowded conditions and nutrient limitations. Accordingly, symbiotic ecosystems with diverse cell species that leak and exchange many metabolites with each other are shaped by cell-level adaptation of leakiness of metabolites. Moreover, the resultant ecosystems with entangled metabolite exchange are resilient against structural and environmental perturbations. Thus, we present a theory for the origin of resilient ecosystems with diverse microbes mediated by secretion and exchange of essential chemicals.

RevDate: 2021-10-18
CmpDate: 2021-10-18

Rajeswari G, Jacob S, Chandel AK, et al (2021)

Unlocking the potential of insect and ruminant host symbionts for recycling of lignocellulosic carbon with a biorefinery approach: a review.

Microbial cell factories, 20(1):107.

Uprising fossil fuel depletion and deterioration of ecological reserves supply have led to the search for alternative renewable and sustainable energy sources and chemicals. Although first generation biorefinery is quite successful commercially in generating bulk of biofuels globally, the food versus fuel debate has necessitated the use of non-edible feedstocks, majorly waste biomass, for second generation production of biofuels and chemicals. A diverse class of microbes and enzymes are being exploited for biofuels production for a series of treatment process, however, the conversion efficiency of wide range of lignocellulosic biomass (LCB) and consolidated way of processing remains challenging. There were lot of research efforts in the past decade to scour for potential microbial candidate. In this context, evolution has developed the gut microbiota of several insects and ruminants that are potential LCB degraders host eco-system to overcome its host nutritional constraints, where LCB processed by microbiomes pretends to be a promising candidate. Synergistic microbial symbionts could make a significant contribution towards recycling the renewable carbon from distinctly abundant recalcitrant LCB. Several studies have assessed the bioprospection of innumerable gut symbionts and their lignocellulolytic enzymes for LCB degradation. Though, some reviews exist on molecular characterization of gut microbes, but none of them has enlightened the microbial community design coupled with various LCB valorization which intensifies the microbial diversity in biofuels application. This review provides a deep insight into the significant breakthroughs attained in enrichment strategy of gut microbial community and its molecular characterization techniques which aids in understanding the holistic microbial community dynamics. Special emphasis is placed on gut microbial role in LCB depolymerization strategies to lignocellulolytic enzymes production and its functional metagenomic data mining eventually generating the sugar platform for biofuels and renewable chemicals production.

RevDate: 2021-10-19
CmpDate: 2021-10-19

Laeverenz Schlogelhofer H, Peaudecerf FJ, Bunbury F, et al (2021)

Combining SIMS and mechanistic modelling to reveal nutrient kinetics in an algal-bacterial mutualism.

PloS one, 16(5):e0251643.

Microbial communities are of considerable significance for biogeochemical processes, for the health of both animals and plants, and for biotechnological purposes. A key feature of microbial interactions is the exchange of nutrients between cells. Isotope labelling followed by analysis with secondary ion mass spectrometry (SIMS) can identify nutrient fluxes and heterogeneity of substrate utilisation on a single cell level. Here we present a novel approach that combines SIMS experiments with mechanistic modelling to reveal otherwise inaccessible nutrient kinetics. The method is applied to study the onset of a synthetic mutualistic partnership between a vitamin B12-dependent mutant of the alga Chlamydomonas reinhardtii and the B12-producing, heterotrophic bacterium Mesorhizobium japonicum, which is supported by algal photosynthesis. Results suggest that an initial pool of fixed carbon delays the onset of mutualistic cross-feeding; significantly, our approach allows the first quantification of this expected delay. Our method is widely applicable to other microbial systems, and will contribute to furthering a mechanistic understanding of microbial interactions.

RevDate: 2021-10-18
CmpDate: 2021-10-18

Souza MLO, Oliveira RJ, Souza DJ, et al (2021)

Differential parasitism by four species of phorid flies when attacking three worker castes of the leaf-cutting ant Atta laevigata (Smith, 1858).

PloS one, 16(5):e0250973.

Certain species of parasitic flies belonging to the Phoridae are known to attack Atta spp. workers foraging along trails, near nest openings used by the ants to supply the colony with plant material, and in the areas where the ants are actively cutting plant material. However, there have been no previous studies of phorid parasitism of non-foraging worker ants, for example excavators and soldiers. Excavators can be found on the surface around specialized nest openings, carrying and dumping soil on characteristic mounds. Soldiers can be found on the trails protecting foragers or guarding the different types of nest openings. The current study was performed to investigate the differential parasitism rates of Atta laevigata (Smith, 1858) worker castes by four species of phorids. Ants of all castes on trails and at nest entrances were collect from 18 mature colonies in the field. A total of 21,254 ants were collected from trails and 14,649 collected from the mounds of loose soil near nest openings. The captured workers were maintained under controlled laboratory conditions to evaluate the rate of parasitism. Of the ants collected from trails, 1,112 (5.23%) were found to have been parasitized, of which 1,102 were foragers and only 10 were soldiers. Of the ants collected from the soil mounds near the nest openings, only 27 (0.18%) were found to have been parasitized, of those 25 were excavators and 2 were soldiers. When evaluating parasitism of ants on the trails, 46.2% were attacked by Apocephalus attophilus Borgmeier, 1928, 22.6% by Myrmosicarius grandicornis Borgmeier, 1928, 16.6% by Eibesfeldtphora erthali (Brown, 2001) and 14.6% by Apocephalus vicosae Disney, 2000. Only two species of phorid, M. grandicornis and E. erthali, were observed parasitizing excavators, whilst only E. erthali parasitized soldiers. This is the first time that Atta spp. excavators and soldiers have been shown to be parasitized by phorids. The low rates of parasitism and specificity of certain phorid species for excavators and soldiers is discussed in relation to the behavioral interactions of hosts and their parasitoids, as well as the relationship between host and parasitoid size.

RevDate: 2021-10-20
CmpDate: 2021-10-20

Singh RA, Boscaro V, James ER, et al (2021)

Characterization of new cristamonad species from kalotermitid termites including a novel genus, Runanympha.

Scientific reports, 11(1):7270.

Cristamonadea is a large class of parabasalian protists that reside in the hindguts of wood-feeding insects, where they play an essential role in the digestion of lignocellulose. This group of symbionts boasts an impressive array of complex morphological characteristics, many of which have evolved multiple times independently. However, their diversity is understudied and molecular data remain scarce. Here we describe seven new species of cristamonad symbionts from Comatermes, Calcaritermes, and Rugitermes termites from Peru and Ecuador. To classify these new species, we examined cells by light and scanning electron microscopy, sequenced the symbiont small subunit ribosomal RNA (rRNA) genes, and carried out barcoding of the mitochondrial large subunit rRNA gene of the hosts to confirm host identification. Based on these data, five of the symbionts characterized here represent new species within described genera: Devescovina sapara n. sp., Devescovina aymara n. sp., Macrotrichomonas ashaninka n. sp., Macrotrichomonas secoya n. sp., and Macrotrichomonas yanesha n. sp. Additionally, two symbionts with overall morphological characteristics similar to the poorly-studied and probably polyphyletic 'joeniid' Parabasalia are classified in a new genus Runanympha n. gen.: Runanympha illapa n. sp., and Runanympha pacha n. sp.

RevDate: 2021-10-20
CmpDate: 2021-10-20

Landuyt AE, Klocke BJ, Duck LW, et al (2021)

ICOS ligand and IL-10 synergize to promote host-microbiota mutualism.

Proceedings of the National Academy of Sciences of the United States of America, 118(13):.

Genome-wide association studies have identified ICOSLG, which encodes the inducible costimulator ligand (ICOSLG or ICOSL) as a susceptibility locus for inflammatory bowel disease. ICOSL has been implicated in the enhancement of pattern recognition receptor signaling in dendritic cells, induction of IL-10 production by CD4 T cells, and the generation of high-affinity antibodies to specific antigens-all of which can potentially explain its involvement in gastrointestinal inflammation. Here, we show that murine ICOSL deficiency results in significant enrichment of IL-10-producing CD4 T cells particularly in the proximal large intestine. Transient depletion of IL-10-producing cells from adult ICOSL-deficient mice induced severe colonic inflammation that was prevented when mice were first treated with metronidazole. ICOSL-deficient mice displayed reduced IgA and IgG antibodies in the colon mucus and impaired serum antibody recognition of microbial antigens, including flagellins derived from mucus-associated bacteria of the Lachnospiraceae family. Confirming the synergy between ICOSL and IL-10, ICOSL deficiency coupled with CD4-specific deletion of the Il10 gene resulted in juvenile onset colitis that was impeded when pups were fostered by ICOSL-sufficient dams. In this setting, we found that both maternally acquired and host-derived antibodies contribute to the life anti-commensal antibody repertoire that mediates this protection in early life. Collectively, our findings reveal a partnership between ICOSL-dependent anti-commensal antibodies and IL-10 in adaptive immune regulation of the microbiota in the large intestine. Furthermore, we identify ICOSL deficiency as an effective platform for exploring the functions of anti-commensal antibodies in host-microbiota mutualism.

RevDate: 2021-10-19
CmpDate: 2021-10-19

Yorifuji M, Yamashita H, Suzuki G, et al (2021)

Unique environmental Symbiodiniaceae diversity at an isolated island in the northwestern Pacific.

Molecular phylogenetics and evolution, 161:107158.

Dinoflagellates in the family Symbiodiniaceae are intensively investigated as algal symbionts of corals and other invertebrates, underpinning coral reef ecosystems as primary producers. Diversity, including regional diversification, of free-living communities is less studied. In this study, an environmental Symbiodiniaceae community at an isolated island, Okinotori Island, Japan, was investigated to determine whether the community is endemic or common with other locations near continents and major ocean currents. Symbiotic algae in common corals at the island were the same type as those of the corals from other Japanese waters. In the environmental samples, genera Symbiodinium (formerly clade A), Cladocopium (clade C), Durusdinium (clade D), and clades F (including Freudenthalidium), G, and I, were identified through analysis of internal transcribed spacer region 2 of nuclear ribosomal RNA gene (ITS2) sequences. Interestingly, some sequences found were genetically different from those of previously reported genera/clades. These unknown sequences were genetically included in the Symbiodiniaceae linage, but they were differentiated from the previously known nine clades. The sequences formed a cluster in the phylogenetic tree based on 28S nrDNA. These sequences were thus considered members of a novel clade in the family (clade J). In total, 120 kinds of ITS2 sequences were produced; while 10 were identical to previously reported sequences, the majority were highly divergent. These genetically unique Symbiodiniaceae types, including novel clade J, may have evolved in isolation and reflect the environmental characteristics of the Okinotori Island.

RevDate: 2021-10-18
CmpDate: 2021-10-18

Nahberger TU, Benucci GMN, Kraigher H, et al (2021)

Effect of earthworms on mycorrhization, root morphology and biomass of silver fir seedlings inoculated with black summer truffle (Tuber aestivum Vittad.).

Scientific reports, 11(1):6167.

Species of the genus Tuber have gained a lot of attention in recent decades due to their aromatic hypogenous fruitbodies, which can bring high prices on the market. The tendency in truffle production is to infect oak, hazel, beech, etc. in greenhouse conditions. We aimed to show whether silver fir (Abies alba Mill.) can be an appropriate host partner for commercial mycorrhization with truffles, and how earthworms in the inoculation substrate would affect the mycorrhization dynamics. Silver fir seedlings inoculated with Tuber. aestivum were analyzed for root system parameters and mycorrhization, how earthworms affect the bare root system, and if mycorrhization parameters change when earthworms are added to the inoculation substrate. Seedlings were analyzed 6 and 12 months after spore inoculation. Mycorrhization with or without earthworms revealed contrasting effects on fine root biomass and morphology of silver fir seedlings. Only a few of the assessed fine root parameters showed statistically significant response, namely higher fine root biomass and fine root tip density in inoculated seedlings without earthworms 6 months after inoculation, lower fine root tip density when earthworms were added, the specific root tip density increased in inoculated seedlings without earthworms 12 months after inoculation, and general negative effect of earthworm on branching density. Silver fir was confirmed as a suitable host partner for commercial mycorrhization with truffles, with 6% and 35% mycorrhization 6 months after inoculation and between 36% and 55% mycorrhization 12 months after inoculation. The effect of earthworms on mycorrhization of silver fir with Tuber aestivum was positive only after 6 months of mycorrhization, while this effect disappeared and turned insignificantly negative after 12 months due to the secondary effect of grazing on ectomycorrhizal root tips.

RevDate: 2021-10-19
CmpDate: 2021-10-19

Karim S, Kumar D, K Budachetri (2021)

Recent advances in understanding tick and rickettsiae interactions.

Parasite immunology, 43(5):e12830.

Ticks are haematophagous arthropods with unique molecular mechanisms for digesting host blood meal while acting as vectors for various pathogens of public health significance. The tick's pharmacologically active saliva plays a fundamental role in modulating the host's immune system for several days to weeks, depending on the tick species. The vector tick has also developed sophisticated molecular mechanisms to serve as a competent vector for pathogens, including the spotted fever group (SFG) rickettsiae. Evidence is still inadequate concerning tick-rickettsiae-host interactions and saliva-assisted transmission of the pathogen to the mammalian host. Rickettsia parkeri, of the SFG rickettsia, can cause a milder version of Rocky Mountain spotted fever known as American Boutonneuse fever. The Gulf Coast tick (Amblyomma maculatum) often transmits this pathogenic rickettsia in the USA. This review discusses the knowledge gap concerning tick-rickettsiae-host interactions by highlighting the SFG rickettsia and the Am maculatum model system. Filling this knowledge gap will provide a better understanding of the tick-rickettsiae-host interactions in disease causation, which will be crucial for developing effective methods for preventing tick-borne diseases.

RevDate: 2021-10-20
CmpDate: 2021-10-20

Wendlandt CE, Helliwell E, Roberts M, et al (2021)

Decreased coevolutionary potential and increased symbiont fecundity during the biological invasion of a legume-rhizobium mutualism.

Evolution; international journal of organic evolution, 75(3):731-747.

Although most invasive species engage in mutualism, we know little about how mutualism evolves as partners colonize novel environments. Selection on cooperation and standing genetic variation for mutualism traits may differ between a mutualism's invaded and native ranges, which could alter cooperation and coevolutionary dynamics. To test for such differences, we compare mutualism traits between invaded- and native-range host-symbiont genotype combinations of the weedy legume, Medicago polymorpha, and its nitrogen-fixing rhizobium symbiont, Ensifer medicae, which have coinvaded North America. We find that mutualism benefits for plants are indistinguishable between invaded- and native-range symbioses. However, rhizobia gain greater fitness from invaded-range mutualisms than from native-range mutualisms, and this enhancement of symbiont fecundity could increase the mutualism's spread by increasing symbiont availability during plant colonization. Furthermore, mutualism traits in invaded-range symbioses show lower genetic variance and a simpler partitioning of genetic variance between host and symbiont sources, compared to native-range symbioses. This suggests that biological invasion has reduced mutualists' potential to respond to coevolutionary selection. Additionally, rhizobia bearing a locus (hrrP) that can enhance symbiotic fitness have more exploitative phenotypes in invaded-range than in native-range symbioses. These findings highlight the impacts of biological invasion on the evolution of mutualistic interactions.

RevDate: 2021-10-19
CmpDate: 2021-10-19

Bonnet SI, T Pollet (2021)

Update on the intricate tango between tick microbiomes and tick-borne pathogens.

Parasite immunology, 43(5):e12813.

The recent development of high-throughput NGS technologies, (ie, next-generation sequencing) has highlighted the complexity of tick microbial communities-which include pathogens, symbionts, and commensals-and also their dynamic variability. Symbionts and commensals can confer crucial and diverse benefits to their hosts, playing nutritional roles or affecting fitness, development, nutrition, reproduction, defence against environmental stress and immunity. Nonpathogenic tick bacteria may also play a role in modifying tick-borne pathogen colonization and transmission, as relationships between microorganisms existing together in one environment can be competitive, exclusive, facilitating or absent, with many potential implications for both human and animal health. Consequently, ticks represent a compelling yet challenging system in which to investigate the composition and both the functional and ecological implications of tick bacterial communities, and thus merits greater attention. Ultimately, deciphering the relationships between microorganisms carried by ticks as well as symbiont-tick interactions will garner invaluable information, which may aid in some future arthropod-pest and vector-borne pathogen transmission control strategies. This review outlines recent research on tick microbiome composition and dynamics, highlights elements favouring the reciprocal influence of the tick microbiome and tick-borne agents and finally discusses how ticks and tick-borne diseases might potentially be controlled through tick microbiome manipulation in the future.

RevDate: 2021-10-18
CmpDate: 2021-10-18

Ballard JWO, SG Towarnicki (2020)

Mitochondria, the gut microbiome and ROS.

Cellular signalling, 75:109737.

In this review, we discuss the connections between mitochondria and the gut microbiome provided by reactive oxygen species (ROS). We examine the mitochondrion as an endosymbiotic organelle that is a hub for energy production, signaling, and cell homeostasis. Maintaining a diverse gut microbiome is generally associated with organismal fitness, intestinal health and resistance to environmental stress. In contrast, gut microbiome imbalance, termed dysbiosis, is linked to a reduction in organismal well-being. ROS are essential signaling molecules but can be damaging when present in excess. Increasing ROS levels have been shown to influence human health, homeostasis of gut cells, and the gastrointestinal microbial community's biodiversity. Reciprocally, gut microbes can affect ROS levels, mitochondrial homeostasis, and host health. We propose that mechanistic understanding of the suite of bi-directional interactions between mitochondria and the gut microbiome will facilitate innovative interdisciplinary studies examining evolutionary divergence and provide novel treatments and therapeutics for disease. GLOSS: In this review, we focus on the nexus between mitochondria and the gut microbiome provided by reactive oxygen species (ROS). Mitochondria are a cell organelle that is derived from an ancestral alpha-proteobacteria. They generate around 80% of the adenosine triphosphate that an organism needs to function and release a range of signaling molecules essential for cellular homeostasis. The gut microbiome is a suite of microorganisms that are commensal, symbiotic and pathogenic to their host. ROS are one predominant group of essential signaling molecules that can be harmful in excess. We suggest that the mitochondria- microbiome nexus is a frontier of research that has cross-disciplinary benefits in understanding genetic divergence and human well-being.

RevDate: 2021-10-18

Boo MV, Chew SF, YK Ip (2021)

The colorful mantle of the giant clam Tridacna squamosa expresses a homolog of electrogenic sodium: Bicarbonate cotransporter 2 that mediates the supply of inorganic carbon to photosynthesizing symbionts.

PloS one, 16(10):e0258519 pii:PONE-D-21-10775.

Giant clams live in symbiosis with phototrophic dinoflagellates, which reside extracellularly inside zooxanthellal tubules located mainly in the colourful and extensible outer mantle. As symbiotic dinoflagellates have no access to the ambient seawater, they need to obtain inorganic carbon (Ci) from the host for photosynthesis during illumination. The outer mantle has a host-mediated and light-dependent carbon-concentrating mechanism to augment the supply of Ci to the symbionts during illumination. Iridocytes can increase the secretion of H+ through vacuolar H+-ATPase to dehydrate HCO3- present in the hemolymph to CO2. CO2 can permeate the basolateral membrane of the epithelial cells of the zooxanthellal tubules, and rehydrated back to HCO3- in the cytoplasm catalysed by carbonic anhydrase 2. This study aimed to elucidate the molecular mechanism involved in the transport of HCO3- across the apical membrane of these epithelial cells into the luminal fluid surrounding the symbionts. We had obtained the complete cDNA coding sequence of a homolog of electrogenic Na+-HCO3- cotransporter 2 (NBCe2-like gene) from the outer mantle of the fluted giant clam, Tridacna squamosa. NBCe2-like gene comprised 3,399 bp, encoding a protein of 1,132 amino acids of 127.3 kDa. NBCe2-like protein had an apical localization in the epithelial cells of zooxanthellal tubules, denoting that it could transport HCO3- between the epithelial cells and the luminal fluid. Furthermore, illumination augmented the transcript level and protein abundance of NBCe2-like gene/NBCe2-like protein in the outer mantle, indicating that it could mediate the increased transport of HCO3- into the luminal fluid to support photosynthesis in the symbionts.

RevDate: 2021-10-15
CmpDate: 2021-10-15

Pernigoni N, Zagato E, Calcinotto A, et al (2021)

Commensal bacteria promote endocrine resistance in prostate cancer through androgen biosynthesis.

Science (New York, N.Y.), 374(6564):216-224.

[Figure: see text].

RevDate: 2021-10-15
CmpDate: 2021-10-15

Smith S, AN Septer (2021)

Quantification of Interbacterial Competition using Single-Cell Fluorescence Imaging.

Journal of visualized experiments : JoVE.

Interbacterial competition can directly impact the structure and function of microbiomes. This work describes a fluorescence microscopy approach that can be used to visualize and quantify competitive interactions between different bacterial strains at the single-cell level. The protocol described here provides methods for advanced approaches in slide preparation on both upright and inverted epifluorescence microscopes, live-cell and time-lapse imaging techniques, and quantitative image analysis using the open-source software FIJI. The approach in this manuscript outlines the quantification of competitive interactions between symbiotic Vibrio fischeri populations by measuring the change in area over time for two coincubated strains that are expressing different fluorescent proteins from stable plasmids. Alternative methods are described for optimizing this protocol in bacterial model systems that require different growth conditions. Although the assay described here uses conditions optimized for V. fischeri, this approach is highly reproducible and can easily be adapted to study competition among culturable isolates from diverse microbiomes.

RevDate: 2021-10-15
CmpDate: 2021-10-15

Tumialis D, Mazurkiewicz A, I Skrzecz (2021)

Effect of agitation speed on the density of bacteria Photorhabdus luminescens and the population dynamics of nematodes Heterorhabditis megidis in liquid culture.

Journal of helminthology, 95:e54 pii:S0022149X21000493.

Liquid culture is the most scalable technology for the industrial production of entomopathogenic nematodes. Variability of the recovery after inoculation into cultures of Photorhabdus luminescens remains a persistent problem in the mass production of Heterorhabditis sp. In order to enhance infective juvenile (IJ) recovery and improve nematode population management, we analysed the correlation between the nematode Heterorhabditis megidis (strain KV - 136) development in liquid cultures, the density of bacteria of P. luminescens and the culture agitation speed. Analyses focused on the impact of different agitation speeds (160 rpm and 200 rpm) on the dynamics of population growth of H. megidis in liquid cultures at constant biotic and abiotic parameters (initial dose of nematodes introduced to the culture 2300 IJs/ml, temperature 25°C, the number of bacterial colonies 0.3 × 107/ml). The performed experiments showed that the agitation speed of 200 rpm favourably affected the density of bacteria of P. luminescens (24.14 × 107/ml). High density of bacteria at this agitation speed resulted in an earlier (on the fifth day of the culture) maximum increase in the number of hermaphroditic individuals (1239.6 H/ml) than in the culture at an agitation speed of 160 rpm.

RevDate: 2021-10-15
CmpDate: 2021-10-15

Yagame T, Lallemand F, Selosse MA, et al (2021)

Mycobiont diversity and first evidence of mixotrophy associated with Psathyrellaceae fungi in the chlorophyllous orchid Cremastra variabilis.

Journal of plant research, 134(6):1213-1224.

Mixotrophy (MX, also called partial mycoheterotrophy) in plants is characterized by isotopic abundances that differ from those of autotrophs. Previous studies have evaluated mycoheterotrophy in MX plants associated with fungi of similar ecological characteristics, but little is known about the differences in the relative abundances of 13C and 15N in an orchid species that associates with several different mycobionts species. Since the chlorophyllous orchid Cremastra variabilis Nakai associates with various fungi with different ecologies, we hypothesized that it may change its relative abundances of 13C and 15N depending on the associated mycobionts. We investigated mycobiont diversity in the chlorophyllous orchid C. variabilis together with the relative abundance of 13C and 15N and morphological underground differentiation (presence or absence of a mycorhizome with fungal colonization). Rhizoctonias (Tulasnellaceae, Ceratobasidiaceae, Sebacinales) were detected as the main mycobionts. High differences in δ13C values (- 34.7 to - 27.4 ‰) among individuals were found, in which the individuals associated with specific Psathyrellaceae showed significantly high relative abundance of 13C. In addition, Psathyrellaceae fungi were always detected on individuals with mycorhizomes. In the present study, MX orchid association with non-rhizoctonia saprobic fungi was confirmed, and the influence of mycobionts on morphological development and on relative abundance of 13C and 15N was discovered. Cremastra variabilis may increase opportunities to gain nutrients from diverse partners, in a bet-hedging plasticity that allows colonization of various environmental conditions.

RevDate: 2021-10-15
CmpDate: 2021-10-15

Tookmanian EM, Belin BJ, Sáenz JP, et al (2021)

The role of hopanoids in fortifying rhizobia against a changing climate.

Environmental microbiology, 23(6):2906-2918.

Bacteria are a globally sustainable source of fixed nitrogen, which is essential for life and crucial for modern agriculture. Many nitrogen-fixing bacteria are agriculturally important, including bacteria known as rhizobia that participate in growth-promoting symbioses with legume plants throughout the world. To be effective symbionts, rhizobia must overcome multiple environmental challenges: from surviving in the soil, to transitioning to the plant environment, to maintaining high metabolic activity within root nodules. Climate change threatens to exacerbate these challenges, especially through fluctuations in soil water potential. Understanding how rhizobia cope with environmental stress is crucial for maintaining agricultural yields in the coming century. The bacterial outer membrane is the first line of defence against physical and chemical environmental stresses, and lipids play a crucial role in determining the robustness of the outer membrane. In particular, structural remodelling of lipid A and sterol-analogues known as hopanoids are instrumental in stress acclimation. Here, we discuss how the unique outer membrane lipid composition of rhizobia may underpin their resilience in the face of increasing osmotic stress expected due to climate change, illustrating the importance of studying microbial membranes and highlighting potential avenues towards more sustainable soil additives.

RevDate: 2021-10-15
CmpDate: 2021-10-15

Castelli M, Lanzoni O, Nardi T, et al (2021)

'Candidatus Sarmatiella mevalonica' endosymbiont of the ciliate Paramecium provides insights on evolutionary plasticity among Rickettsiales.

Environmental microbiology, 23(3):1684-1701.

Members of the bacterial order Rickettsiales are obligatorily associated with a wide range of eukaryotic hosts. Their evolutionary trajectories, in particular concerning the origin of shared or differential traits among distant sub-lineages, are still poorly understood. Here, we characterized a novel Rickettsiales bacterium associated with the ciliate Paramecium tredecaurelia and phylogenetically related to the Rickettsia genus. Its genome encodes significant lineage-specific features, chiefly the mevalonate pathway gene repertoire, involved in isoprenoid precursor biosynthesis. Not only this pathway has never been described in Rickettsiales, it also is very rare among bacteria, though typical in eukaryotes, thus likely representing a horizontally acquired trait. The presence of these genes could enable an efficient exploitation of host-derived intermediates for isoprenoid synthesis. Moreover, we hypothesize the reversed reactions could have replaced canonical pathways for producing acetyl-CoA, essential for phospholipid biosynthesis. Additionally, we detected phylogenetically unrelated mevalonate pathway genes in metagenome-derived Rickettsiales sequences, likely indicating evolutionary convergent effects of independent horizontal gene transfer events. Accordingly, convergence, involving both gene acquisitions and losses, is highlighted as a relevant evolutionary phenomenon in Rickettsiales, possibly favoured by plasticity and comparable lifestyles, representing a potentially hidden origin of other more nuanced similarities among sub-lineages.

RevDate: 2021-10-15
CmpDate: 2021-10-15

Qin M, Chen J, Xu S, et al (2021)

Microbiota associated with Mollitrichosiphum aphids (Hemiptera: Aphididae: Greenideinae): diversity, host species specificity and phylosymbiosis.

Environmental microbiology, 23(4):2184-2198.

Symbiotic association is universal in nature, and an array of symbionts play a crucial part in host life history. Aphids and their diverse symbionts have become a good model system to study insect-symbiont interactions. Previous symbiotic diversity surveys have mainly focused on a few aphid clades, and the relative importance of different factors regulating microbial community structure is not well understood. In this study, we collected 65 colonies representing eight species of the aphid genus Mollitrichosiphum from different regions and plants in southern China and Nepal and characterized their microbial compositions using Illumina sequencing of the V3 - V4 hypervariable region of the 16S rRNA gene. We evaluated how microbiota varied across aphid species, geography and host plants and the correlation between microbial community structure and host aphid phylogeny. Heritable symbionts dominated the microbiota associated with Mollitrichosiphum, and multiple infections of secondary symbionts were prevalent. Ordination analyses and statistical tests highlighted the contribution of aphid species in shaping the structures of bacterial, symbiont and secondary symbiont communities. Moreover, we observed a significant correlation between Mollitrichosiphum aphid phylogeny and microbial community composition, providing evidence for a pattern of phylosymbiosis between natural aphid populations and their microbial associates.

RevDate: 2021-10-15
CmpDate: 2021-10-15

Lukito Y, Lee K, Noorifar N, et al (2021)

Regulation of host-infection ability in the grass-symbiotic fungus Epichloë festucae by histone H3K9 and H3K36 methyltransferases.

Environmental microbiology, 23(4):2116-2131.

Recent studies have identified key genes that control the symbiotic interaction between Epichloë festucae and Lolium perenne. Here we report on the identification of specific E. festucae genes that control host infection. Deletion of setB, which encodes a homologue of the H3K36 histone methyltransferase Set2/KMT3, reduced histone H3K36 trimethylation and led to severe defects in colony growth and hyphal development. The E. festucae ΔclrD mutant, which lacks the gene encoding the homologue of the H3K9 methyltransferase KMT1, displays similar developmental defects. Both mutants are completely defective in their ability to infect L. perenne. Alleles that complement the culture and plant phenotypes of both mutants also complement the histone methylation defects. Co-inoculation of either ΔsetB or ΔclrD with the wild-type strain enables these mutants to colonize the host. However, successful colonization by the mutants resulted in death or stunting of the host plant. Transcriptome analysis at the early infection stage identified four fungal candidate genes, three of which encode small-secreted proteins, that are differentially regulated in these mutants compared to wild type. Deletion of crbA, which encodes a putative carbohydrate binding protein, resulted in significantly reduced host infection rates by E. festucae.

RevDate: 2021-10-14

Bahareh Nowruzi , Bouaïcha N, Metcalf JS, et al (2021)

Plant-cyanobacteria interactions: Beneficial and harmful effects of cyanobacterial bioactive compounds on soil-plant systems and subsequent risk to animal and human health.

Phytochemistry, 192:112959 pii:S0031-9422(21)00308-3 [Epub ahead of print].

Plant-cyanobacteria interactions occur in different ways and at many different levels, both beneficial and harmful. Plant-cyanobacteria interactions, as a beneficial symbiosis, have long been demonstrated in rice-growing areas (Poaceae) where the most efficient nitrogen-fixing cyanobacteria are present in paddies. Moreover, cyanobacteria may in turn produce and/or secrete numerous bioactive compounds that have plant growth-promoting abilities or that may make the plant more resistant to abiotic or biotic stress. In recent years, there has been a growing worldwide interest in the use of cyanobacterial biomass as biofertilizers to replace chemical fertilizers, in part to overcome increasing organic-farming demands. However, the potential presence of harmful cyanotoxins has delayed the use of such cyanobacterial biomass, which can be found in large quantities in freshwater ecosystems around the world. In this review, we describe the existing evidence for the positive benefit of plant-cyanobacteria interactions and discuss the use of cyanobacterial biomass as biofertilizers and its growing worldwide interest. Although mass cyanobacterial blooms and scums are a current and emerging threat to the degradation of ecosystems and to animal and human health, they may serve as a source of numerous bioactive compounds with multiple positive effects that could be of use as an alternative to chemical fertilizers in the context of sustainable development.

RevDate: 2021-10-14

Rhem MFK, Silva VC, Dos Santos JMF, et al (2021)

The large mimosoid genus Inga Mill. (tribe Ingeae, Caesalpinioideae) is nodulated by diverse Bradyrhizobium strains in its main centers of diversity in Brazil.

Systematic and applied microbiology, 44(6):126268 pii:S0723-2020(21)00091-6 [Epub ahead of print].

Inga (Caesalpinioideae) is the type genus of the Ingeae tribe in the mimosoid clade. It comprises about 300 species, all trees or treelets, and has an exclusively neotropical distribution, with Brazil as its main center of diversity. In this study, we analyzed the diversity of 40 strains of rhizobia isolated from root nodules collected from ten species of Inga belonging to different types of vegetation in Brazil. Sequences of their housekeeping genes (dnaK, recA, rpoB, gyrB and glnII), 16S rRNA genes, internal transcribed spacer (ITS) regions, as well as their symbiosis-essential genes (nodC and nifH) were used to characterize them genetically. The ability of the rhizobia to form nodules on Inga spp., and on the promiscuous legume siratro (Macroptilium atropurpureum) was also evaluated. A multilocus sequence analysis (MLSA) combined with an analysis of the ITS region showed that the isolates were distributed into four main groups (A-D) within the large genus Bradyrhizobium. Analysis of the nodC and nifH genes showed that the isolates formed a separate branch from all described species of Bradyrhizobium, except for B. ingae. Most of the tested isolates formed nodules on siratro and all isolates tested nodulated Inga spp. Our results suggest a unique co-evolutionary history of Bradyrhizobium and Inga and demonstrate the existence of potential new species of microsymbionts nodulating this important and representative genus of leguminous tree from the Caesalpinioideae mimosoid clade.

RevDate: 2021-10-14

Sakai HD, Matsuda R, Imura S, et al (2021)

Complete Genome and Plasmid Sequences of the Psychrotolerant Aureimonas Strain SA4125, Isolated from Antarctic Moss Vegetation.

Microbiology resource announcements, 10(41):e0087821.

The complete genome sequences of Aureimonas sp. strain SA4125 and its native plasmid pSA4125 were determined. The genome sequence comprises 4,968,066 bp, with a GC content of 66.0%, and contains 4,691 coding DNA sequences (CDSs), 3 rRNA operons, and 50 tRNAs. The native plasmid comprises 131,777 bp, with a GC content of 62.3%, and contains 138 CDSs.

RevDate: 2021-10-13

Shi J, Zhao B, Zheng S, et al (2021)

A phosphate starvation response-centered network regulates mycorrhizal symbiosis.

Cell pii:S0092-8674(21)01113-2 [Epub ahead of print].

To secure phosphorus (P) from soil, most land plants use a direct phosphate uptake pathway via root hairs and epidermis and an indirect phosphate uptake pathway via mycorrhizal symbiosis. The interaction between these two pathways is unclear. Here, we mapped a network between transcription factors and mycorrhizal symbiosis-related genes using Y1H. Intriguingly, this gene regulatory network is governed by the conserved P-sensing pathway, centered on phosphate starvation response (PHR) transcription factors. PHRs are required for mycorrhizal symbiosis and regulate symbiosis-related genes via the P1BS motif. SPX-domain proteins suppress OsPHR2-mediated induction of symbiosis-related genes and inhibit mycorrhizal infection. In contrast, plants overexpressing OsPHR2 show improved mycorrhizal infection and are partially resistant to P-mediated inhibition of symbiosis. Functional analyses of network nodes revealed co-regulation of hormonal signaling and mycorrhizal symbiosis. This network deciphers extensive regulation of mycorrhizal symbiosis by endogenous and exogenous signals and highlights co-option of the P-sensing pathway for mycorrhizal symbiosis.

RevDate: 2021-10-13

Bhagwat AC, Patil AM, SD Saroj (2021)

CRISPR/Cas 9-Based Editing in the Production of Bioactive Molecules.

Molecular biotechnology [Epub ahead of print].

Plants, fungi, and bacteria synthesize a wide range of secondary metabolites that exhibit diverse biological activities. These bioactives, due to their potential benefits in research and therapeutics, have gained immense industrial importance. There is a need to synthesize these bioactives at significantly higher concentrations using cost-effective measures to be economically viable. However, the broader study of industrially important secondary metabolites has been hindered, thus, far due to a shortage of reliable, comparatively easy, and highly effective gene manipulation techniques. With the advent of Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR/Cas), there is a revolution in the field of genetic engineering. CRISPR/Cas system, due to its simplicity and ease of use. This has widened its application in plant breeding, strain improvement, and engineering the metabolic pathways involved in the biochemical synthesis of industrially valuable bioactive. This review briefly introduces the CRISPR/Cas9 system and summarizes the applications of CRISPR/Cas9-mediated editing tools for the production of plant and fungal-derived bioactives.

RevDate: 2021-10-13

Sharma A, Kumar V, Babbar A, et al (2021)

Experimental Investigation and Optimization of Electric Discharge Machining Process Parameters Using Grey-Fuzzy-Based Hybrid Techniques.

Materials (Basel, Switzerland), 14(19): pii:ma14195820.

Electrical discharge machining (EDM) has recently been shown to be one of the most successful unconventional machining methods for meeting the requirements of today's manufacturing sector by producing complicated curved geometries in a broad variety of contemporary engineering materials. The machining efficiency of an EDM process during hexagonal hole formation on pearlitic Spheroidal Graphite (SG) iron 450/12 grade material was examined in this study utilizing peak current (I), pulse-on time (Ton), and inter-electrode gap (IEG) as input parameters. The responses, on the other hand, were the material removal rate (MRR) and overcut. During the experimental trials, the peak current ranged from 32 to 44 A, the pulse-on duration ranged from 30-120 s, and the inter-electrode gap ranged from 0.011 to 0.014 mm. Grey relational analysis (GRA) was interwoven with a fuzzy logic method to optimize the multi-objective technique that was explored in this EDM process. The effect of changing EDM process parameter values on responses was further investigated and statistically analyzed. Additionally, a response graph and response table were produced to determine the best parametric setting based on the calculated grey-fuzzy reasoning grade (GFRG). Furthermore, predictor regression models for response characteristics and GFRG were constructed, and a confirmation test was performed using randomly chosen input parameters to validate the generated models.

RevDate: 2021-10-13

Dendl K, Koerber SA, Kratochwil C, et al (2021)

FAP and FAPI-PET/CT in Malignant and Non-Malignant Diseases: A Perfect Symbiosis?.

Cancers, 13(19): pii:cancers13194946.

A fibroblast activation protein (FAP) is an atypical type II transmembrane serine protease with both endopeptidase and post-proline dipeptidyl peptidase activity. FAP is overexpressed in cancer-associated fibroblasts (CAFs), which are found in most epithelial tumors. CAFs have been implicated in promoting tumor cell invasion, angiogenesis and growth and their presence correlates with a poor prognosis. However, FAP can generally be found during the remodeling of the extracellular matrix and therefore can be detected in wound healing and benign diseases. For instance, chronic inflammation, arthritis, fibrosis and ischemic heart tissue after a myocardial infarction are FAP-positive diseases. Therefore, quinoline-based FAP inhibitors (FAPIs) bind with a high affinity not only to tumors but also to a variety of benign pathologic processes. When these inhibitors are radiolabeled with positron emitting radioisotopes, they provide new diagnostic and prognostic tools as well as insights into the role of the microenvironment in a disease. In this respect, they deliver additional information beyond what is afforded by conventional FDG PET scans that typically report on glucose uptake. Thus, FAP ligands are considered to be highly promising novel tracers that offer a new diagnostic and theranostic potential in a variety of diseases.

RevDate: 2021-10-13
CmpDate: 2021-10-13

Priyadarshini P, Choudhury S, Tilgam J, et al (2021)

Nitrogen fixing cereal: A rising hero towards meeting food security.

Plant physiology and biochemistry : PPB, 167:912-920.

Nitrogen serves as one of the primary components of major biomolecules and thus extends a significant contribution to crop growth and yield. But the inability of plants to utilize freely available atmospheric N2 makes the whole agricultural system dependent on chemical fertilizers, which incur significant input cost to supplement required quantities of nitrogen to crops. Only bacteria and archaea have been gifted with the power of drawing free N2 from air to convert them into NH3, which is one of the two utilizable forms of nitrogen taken up by plants. Legumes, the only family of crops, can engage themselves in symbiotic nitrogen fixation where they establish a mutualistic relationship with nitrogen-fixing bacteria and in turn, can waive off the necessity of adding nitrogen fertilizers. Sincere effort, therefore, has been undertaken to incorporate this capability of nitrogen-fixation into non-legume crops, especially cereals which make up a vital portion in the food basket. Biotechnological interventions have also played important role in providing nitrogen fixing trait to non-legumes. This review takes up an effort to look into and accumulate all the important updates to date regarding nitrogen-fixing non-legumes with a special focus on cereals, which is one of the most important future goals in the field of science in the present era.

RevDate: 2021-10-13
CmpDate: 2021-10-13

Banasiewicz J, Lisboa BB, da Costa PB, et al (2021)

Culture-independent assessment of the diazotrophic Bradyrhizobium communities in the Pampa and Atlantic Forest Biomes localities in southern Brazil.

Systematic and applied microbiology, 44(4):126228.

The isolation of rhizobial strains from the root and stem nodules remains a commonly used method despite its limitations as it enables the identification of mainly dominant symbiotic groups within rhizobial communities. To overcome these limitations, we used genus-specific nifD primers in a culture-independent assessment of Bradyrhizobium communities inhabiting soils in southern Brazil. The majority of nifD sequences were generated from DNA isolated from tropical-lowland pasture soils, although some soil samples originated from the Campos de Cima da Serra volcanic plateau. In the nifD tree, all the bradyrhizobial sequences comprised 38 clades, including 18 new clades. The sequences generated in this study were resolved into 22 clades and 21 singletons. The nifD bradyrhizobial assemblage contained Azorhizobium and α-proteobacterial methylotrophic genera, suggesting that these genera may have acquired their nif loci from Bradyrhizobium donors. The most common in the lowland pasture soils subclade III.3D branch comprises the isolates of mainly an American origin. On the other hand, subclade III.4, which was earlier detected in Brazil among Bradyrhizobium isolates nodulating native lupins, appears more common in the Campos de Cima da Serra soils. The second-largest group, Clade XXXVIII, has not yet been reported in culture-dependent studies, while another common group called Clade I represents a symbiovar predominating in Australia. The identification of the diverse nifD Clade I haplotypes in the tropical-lowland pastures infested by Australian Acacia spp implies that the introduction of these legumes to southern Brazil has resulted in the dissemination of their bradyrhizobial symbionts.

RevDate: 2021-10-14
CmpDate: 2021-10-14

Duarte EH, Carvalho A, López-Madrigal S, et al (2021)

Forward genetics in Wolbachia: Regulation of Wolbachia proliferation by the amplification and deletion of an addictive genomic island.

PLoS genetics, 17(6):e1009612.

Wolbachia is one of the most prevalent bacterial endosymbionts, infecting approximately 40% of terrestrial arthropod species. Wolbachia is often a reproductive parasite but can also provide fitness benefits to its host, as, for example, protection against viral pathogens. This protective effect is currently being applied to fight arboviruses transmission by releasing Wolbachia-transinfected mosquitoes. Titre regulation is a crucial aspect of Wolbachia biology. Higher titres can lead to stronger phenotypes and fidelity of transmission but can have a higher cost to the host. Since Wolbachia is maternally transmitted, its fitness depends on host fitness, and, therefore, its cost to the host may be under selection. Understanding how Wolbachia titres are regulated and other aspects of Wolbachia biology has been hampered by the lack of genetic tools. Here we developed a forward genetic screen to identify new Wolbachia over-proliferative mutant variants. We characterized in detail two new mutants, wMelPop2 and wMelOctoless, and show that the amplification or loss of the Octomom genomic region lead to over-proliferation. These results confirm previous data and expand on the complex role of this genomic region in the control of Wolbachia proliferation. Both new mutants shorten the host lifespan and increase antiviral protection. Moreover, we show that Wolbachia proliferation rate in Drosophila melanogaster depends on the interaction between Octomom copy number, the host developmental stage, and temperature. Our analysis also suggests that the life shortening and antiviral protection phenotypes of Wolbachia are dependent on different, but related, properties of the endosymbiont; the rate of proliferation and the titres near the time of infection, respectively. We also demonstrate the feasibility of a novel and unbiased experimental approach to study Wolbachia biology, which could be further adapted to characterize other genetically intractable bacterial endosymbionts.

RevDate: 2021-10-13
CmpDate: 2021-10-13

Simbine MG, Jaiswal SK, FD Dakora (2021)

Diverse symbiovars nodulating cowpea (Vigna unguiculata L. Walp.) in highly adaptable agro-ecological zones in Mozambique.

Systematic and applied microbiology, 44(4):126220.

The presence of effective microsymbionts in the soil and their compatibility with the host plant are the key determinants to the N2 fixation process. In Sub-Saharan Africa, nitrogen fixation in locally adapted cowpea and the distribution of their symbiovars are not well understood. The Aim of the study was to assess the distribution and symbiotic phylogenetic position of cowpea microsymbionts. Root nodules were sampled from various cowpea genotypes planted in Agro-Ecological Zone 7 and 8 (AEZ 7 and AEZ 8). Root-nodule bacteria were isolated and their molecular characterization was conducted. Physicochemical properties of soil were recorded. Enterobacterial Repetitive Intergenic Consensus (ERIC) distribution patterns in rhizobial genomes resulted in genetically diverse rhizobial population in Northern Mozambique. Principal component analysis showed that location-specific soil environment determined the presence of particular microsymbionts. Based on 16S rRNA and symbiotic gene analysis many diverse symbiovars were found in Mozambican soils. With few discrepancies, the results further confirmed the coevolution of the nifH, nodD, nodC and nodY/K genes, which was indicative of natural events such as vertical/horizontal gene transfer. The results suggested that ecological and phylogenetic studies of the microsymbionts are necessary to better reflect symbiovar identification and the ecological adaptation of the cowpea-nodulating rhizobial community.

RevDate: 2021-10-13
CmpDate: 2021-10-13

Ilahi H, Hsouna J, Ellouze W, et al (2021)

Phylogenetic study of rhizobia nodulating pea (Pisum sativum) isolated from different geographic locations in Tunisia.

Systematic and applied microbiology, 44(4):126221.

Nodulated Pisum sativum plants showed the presence of native rhizobia in 16 out of 23 soil samples collected especially in northern and central Tunisia. A total of 130 bacterial strains were selected and three different ribotypes were revealed after PCR-RFLP analysis. Sequence analyses of rrs and four housekeeping genes (recA, atpD, dnaK and glnII) assigned 35 isolates to Rhizobium laguerreae, R. ruizarguesonis, Agrobacterium radiobacter, Ensifer meliloti and two putative genospecies. R. laguerreae was the most dominant species nodulating P. sativum with 63%. The isolates 21PS7 and 21PS15 were assigned to R. ruizarguesonis, and this is the first report of this species in Tunisia. Two putative new lineages were identified, since strains 25PS6, 10PS4 and 12PS15 clustered distinctly from known rhizobia species but within the R. leguminosarum complex (Rlc) with the most closely related species being R. indicum with 96.4% sequence identity. Similarly, strains 16PS2, 3PS9 and 3PS18 showed 97.4% and 97.6% similarity with R. sophorae and R. laguerreae, respectively. Based on 16S-23S intergenic spacer (IGS) fingerprinting, there was no clear association between the strains and their geographic locations. According to nodC and nodA phylogenies, strains of Rlc species and, interestingly, strain 8PS18 identified as E. meliloti, harbored the symbiotic genes of symbiovar viciae and clustered in two different clades showing heterogeneity within the symbiovar. All these strains nodulated and fixed nitrogen with pea plants. However, the strains belonging to A. radiobacter and the two remaining strains of E. meliloti were unable to nodulate P. sativum, suggesting that they were non-symbiotic strains. The results of this study further suggest that the Tunisian Rhizobium community is more diverse than previously reported.

RevDate: 2021-10-14
CmpDate: 2021-10-14

Herp S, Durai Raj AC, Salvado Silva M, et al (2021)

The human symbiont Mucispirillum schaedleri: causality in health and disease.

Medical microbiology and immunology, 210(4):173-179.

Trillions of bacteria inhabit the mammalian gastrointestinal tract. In the majority of hosts, these symbionts contribute largely to beneficial functions promoting microbe-host homeostasis. However, an increasing number of human diseases is associated with altered microbiota composition and enrichment of certain bacterial species. A well-known example of this is Mucispirillum schaedleri, which has been associated with inflammatory conditions in the intestine. Mucispirillum spp. belong to the phylum Deferribacteres and are prevalent but low abundant members of the rodent, pig and human microbiota. Recently, M. schaedleri was causally linked to the development of Crohn's disease-like colitis in immunodeficient mice. While this study certifies a considerable pathogenic potential, the same organism can also promote health in the immunocompetent host: M. schaedleri protects from Salmonella enterica serovar Typhimurium (S. Tm)-induced colitis by interfering with the expression of the pathogen´s invasion machinery. In this review, we summarize the current knowledge on the mammalian gut symbiont M. schaedleri and its role in intestinal homeostasis and discuss open questions and perspectives for future research.

RevDate: 2021-10-13
CmpDate: 2021-10-13

Alami S, Lamin H, Bennis M, et al (2021)

Characterization of Retama sphaerocarpa microsymbionts in Zaida lead mine tailings in the Moroccan middle Atlas.

Systematic and applied microbiology, 44(3):126207.

In the Moroccan Middle Atlas, the tailings rich in lead and other metal residues, in the abandoned Zaida mining district, represent a real threat to environment and the neighboring villages' inhabitants' health. In this semi-arid to arid area, phytostabilisation would be the best choice to limit the transfer of heavy metals to populations and groundwater. The aim of this work was to characterize the bacteria that nodulate Retama sphaerocarpa, spontaneous nitrogen fixing shrubby legume, native to the Zaida mining area, with great potential to develop for phytostabilisation. Forty-three bacteria isolated from root nodules of the plant were characterized. Based on REP-PCR and ARDRA, four strains were selected for further molecular analyzes. The 16S rRNA gene sequences analysis revealed that the isolated strains are members of the genus Bradyrhizobium, and the phylogenetic analysis of the housekeeping genes glnII, atpD, gyrB, rpoB, recA and dnaK individual sequences and their concatenation showed that the strains are close to B. algeriense RST89T and B. valentinum LmjM3T with similarity percentages of 89.07% to 95.66% which suggest that the newly isolated strains from this mining site may belong to a potential novel species. The phylogeny of the nodA and nodC genes showed that the strains belong to the symbiovar retamae of the genus Bradyrhizobium. These strains nodulate also R. monosperma, R. dasycarpa and Lupinus luteus.

RevDate: 2021-10-14
CmpDate: 2021-10-14

Cho K, Spasova D, Hong SW, et al (2021)

Listeria monocytogenes Establishes Commensalism in Germ-Free Mice Through the Reversible Downregulation of Virulence Gene Expression.

Frontiers in immunology, 12:666088.

The intestine harbors a complex community of bacterial species collectively known as commensal microbiota. Specific species of resident bacteria, as known as pathobiont, have pathogenic potential and can induce apparent damage to the host and intestinal inflammation in a certain condition. However, the host immune factors that permit its commensalism under steady state conditions are not clearly understood. Here, we studied the gut fitness of Listeria monocytogenes by using germ-free (GF) mice orally infected with this food-borne pathogen. L. monocytogenes persistently exists in the gut of GF mice without inducing chronic immunopathology. L. monocytogenes at the late phase of infection is not capable of infiltrating through the intestinal barrier. L. monocytogenes established the commensalism through the reversible down regulation of virulence gene expression. CD8+ T cells were found to be sufficient for the commensalism of L. monocytogenes. CD8+ T cells responding to L. monocytogenes contributed to the down-regulation of virulence gene expression. Our data provide important insights into the host-microbe interaction and have implications for developing therapeutics against immune disorders induced by intestinal pathogens or pathobionts.

RevDate: 2021-10-13
CmpDate: 2021-10-13

Dias MAM, Bomfim CSG, Rodrigues DR, et al (2021)

Paraburkholderia spp. are the main rhizobial microsymbionts of Mimosa tenuiflora (Willd.) Poir. in soils of the Brazilian tropical dry forests (Caatinga biome).

Systematic and applied microbiology, 44(3):126208.

Mimosa tenuiflora (Willd.) Poir. is widespread in southern and central American drylands, but little information is available concerning its associated rhizobia. Therefore, this study aimed to characterize M. tenuiflora rhizobia from soils of the tropical dry forests (Caatinga) in Pernambuco State, Brazil, at the molecular and symbiotic levels. Soil samples of pristine Caatinga areas in four municipalities were used to grow M. tenuiflora. First, the bacteria from root nodules were subjected to nodC/nifH gene amplification, and the bacteria positive for both genes had the 16S rRNA gene sequenced. Then, ten strains were evaluated using recA, gyrB, and nodC gene sequences, and seven of them had their symbiotic efficiency assessed. Thirty-two strains were obtained and 22 of them were nodC/nifH positive. Twenty strains clustered within Paraburkholderia and two within Rhizobium by 16S rRNA gene sequencing. The beta-rhizobia were similar to P. phenoliruptrix (12) and P. diazotrophica (8). Both alpha-rhizobia were closely related to R. miluonense. The recA + gyrB phylogenetic analysis clustered four and five strains within the P. phenoliruptrix and P. diazotrophica branches, respectively, but they were somewhat divergent to the 16S rRNA phylogeny. For Rhizobium sp. ESA 637, the recA + gyrB phylogeny clustered the strain with R. jaguaris. The nodC phylogeny indicated that ESA 626, ESA 629, and ESA 630 probably represented a new symbiovar branch. The inoculation assay showed high symbiotic efficiency for all tested strains. The results indicated high genetic diversity and efficiency of M. tenuiflora rhizobia in Brazilian drylands and included P. phenoliruptrix-like bacteria in the list of efficient beta-rhizobia in the Caatinga biome.

RevDate: 2021-10-13
CmpDate: 2021-10-13

Fuess LE, den Haan S, Ling F, et al (2021)

Immune Gene Expression Covaries with Gut Microbiome Composition in Stickleback.

mBio, 12(3):.

Commensal microbial communities have immense effects on their vertebrate hosts, contributing to a number of physiological functions, as well as host fitness. In particular, host immunity is strongly linked to microbiota composition through poorly understood bi-directional links. Gene expression may be a potential mediator of these links between microbial communities and host function. However, few studies have investigated connections between microbiota composition and expression of host immune genes in complex systems. Here, we leverage a large study of laboratory-raised fish from the species Gasterosteus aculeatus (three-spined stickleback) to document correlations between gene expression and microbiome composition. First, we examined correlations between microbiome alpha diversity and gene expression. Our results demonstrate robust positive associations between microbial alpha diversity and expression of host immune genes. Next, we examined correlations between host gene expression and abundance of microbial taxa. We identified 15 microbial families that were highly correlated with host gene expression. These families were all tightly correlated with host expression of immune genes and processes, falling into one of three categories-those positively correlated, negatively correlated, and neutrally related to immune processes. Furthermore, we highlight several important immune processes that are commonly associated with the abundance of these taxa, including both macrophage and B cell functions. Further functional characterization of microbial taxa will help disentangle the mechanisms of the correlations described here. In sum, our study supports prevailing hypotheses of intimate links between host immunity and gut microbiome composition.IMPORTANCE Here, we document associations between host gene expression and gut microbiome composition in a nonmammalian vertebrate species. We highlight associations between expression of immune genes and both microbiome diversity and abundance of specific microbial taxa. These findings support other findings from model systems which have suggested that gut microbiome composition and host immunity are intimately linked. Furthermore, we demonstrate that these correlations are truly systemic; the gene expression detailed here was collected from an important fish immune organ (the head kidney) that is anatomically distant from the gut. This emphasizes the systemic impact of connections between gut microbiota and host immune function. Our work is a significant advancement in the understanding of immune-microbiome links in nonmodel, natural systems.

RevDate: 2021-10-13
CmpDate: 2021-10-13

Banasiewicz J, Granada CE, Lisboa BB, et al (2021)

Diversity and phylogenetic affinities of Bradyrhizobium isolates from Pampa and Atlantic Forest Biomes.

Systematic and applied microbiology, 44(3):126203.

In this work, we investigated Bradyrhizobium strains isolated from soils collected from the rhizosphere of native and exotic legumes species inhabiting two ecoclimatic zones - asubtropical-lowland pasture (Pampa Biome) and a volcanic plateau covered by Araucaria Moist Forests (Atlantic Forest Biome). The rhizobial strains were isolated from the nodules of seven native and one exotic legume species used as rhizobium traps. Single-gene (recA, glnII, dnaK) and combined-gene MLSA analyses (dnaK-glnII-gyrB-recA-rpoB) revealed that nearly 85% of the isolates clustered in B. elkanii supergroup, while the remaining (except for two isolates) in B. japonicum supergroup, albeit, in most cases, separately from the type strains of Bradyrhizobium species. As a symbiotic gene marker, a portion of nifD gene was sequenced for 194 strains. In the nifD-tree, an American branch III.3D (104 isolates), was the most numerous among the isolates. A significant portion of the isolates clustered in American groups; subclade III.4 (40 strains), Clade VII (3 strains), and a new Clade XX (4 strains). Most of the remaining strains belonged to a pantropical III.3C branch (39 isolates). On the other hand, identification of isolates belonging, respectively, to Clade I and Clade II may result of spreading of the Australian (Clade I) and European (Clade II) bradyrhizobia following the introduction of their legume hosts. Our study indicated that the American groups predominated in the symbiotic Bradyrhizobium communities in southern Brazil. However, there is a significant component of exotic lineages, resulting from the dispersal of pantropical Fabaceae taxa and the introduction of exotic legumes.

RevDate: 2021-10-13
CmpDate: 2021-10-13

Bouhnik O, Lamin H, Alami S, et al (2021)

The endemic Chamaecytisus albidus is nodulated by symbiovar genistearum of Bradyrhizobium in the Moroccan Maamora Forest.

Systematic and applied microbiology, 44(3):126197.

Out of 54 isolates from root nodules of the Moroccan-endemic Chamaecytisus albidus plants growing in soils from the Maamora cork oak forest, 44 isolates formed nodules when used to infect their original host plant. A phenotypic analysis showed the metabolic diversity of the strains that used different carbohydrates and amino acids as sole carbon and nitrogen sources. The isolates grew on media with pH values ranging from 6 to 8. However, they did not tolerate high temperatures or drought and they did not grow on media with salt concentrations higher than 85 mM. REP-PCR fingerprinting grouped the strains into 12 clusters, of which representative strains were selected for ARDRA and rrs analyses. The rrs gene sequence analysis indicated that all 12 strains were members of the genus Bradyrhizobium and their phylogeny showed that they were grouped into two different clusters. Two strains from each group were selected for multilocus sequence analysis (MLSA) using atpD, recA, gyrB and glnII housekeeping genes. The inferred phylogenetic trees confirmed that the strains clustered into two divergent clusters. Strains CM55 and CM57 were affiliated to the B. canariense/B. lupini group, whereas strains CM61 and CM64 were regrouped within the B. cytisi/B. rifense lineage. The analysis of the nodC symbiotic gene affiliated the strains to the symbiovar genistearum. The strains were also able to nodulate Retama monosperma, Lupinus luteus and Cytisus monspessulanus, but not Phaseolus vulgaris or Glycine max. Inoculation tests with C. albidus showed that some strains could be exploited as efficient inocula that could be used to improve plant growth in the Maamora forest.

RevDate: 2021-10-13
CmpDate: 2021-10-13

Jissin M, C Vani (2020)

Biogenic larvicidal formulation of metabolites from Steinernema saimkayi symbiont Xenorhabdus stockiae KUT6 against dengue vector Aedes aegypti.

Tropical biomedicine, 37(3):791-802.

To characterize the production and larvicidal activity of Xenorhabdus stockiae KUT6 Petroleum ether extracts from Luria Broth and induced Quorum sensing medium containing N-3- oxododecanoyl Homoserine Lactone inducer against dengue vector Aedes aegypti. The Galleria mellonella larvae were reared for the isolation of Steinernema saimkayi symbiont Xenorhabdus stockiae KUT6 from Cucumber field soil sample in NBTA. Then for the extraction of compounds the KUT6 strains were cultured in Luria Broth and Quorum Sensing optimized media using N-3-oxododecanoyl homoserine lactone inducer. The larvicidal activity of Xenorhabdus stockiae KUT6 of petroleum ether extracts were bioassayed against 4th instar Aedes aegypti dengue vector. The maximum rate of mortality were recorded of the samples A-24h, B-48h, C-72h, A1-24h, B1-48h, C1-72h at different concentrations 50 µg/ml, 100 µg/ml and 150 µg/ml respectively for 24h to 72h of exposure treatment. The morphological characteristics of Xenorhabdus stockiae KUT6 in NBTA were red core colonies with blue background surrounded by zone of inhibition. After 24h exposure maximum rate of 100% mortality of Aedes aegypti 4th instar larvae was attained when treated with sample C1-72h 50 µg/ml of the petroleum ether extracts of quorum sensed medium whereas the sample C 72h petroleum ether extracts of KUT6 cultured in Luria broth recorded 100% mortality at 150 µg on 24h exposure indicates enhancement in the product yield. The study assures the use of Xenorhabdus stockiae KUT6 petroleum ether extracts as biocontrol agent could be beneficial for the control of dengue vectors.

RevDate: 2021-10-13
CmpDate: 2021-10-13

Sharma V, Gupta P, Priscilla K, et al (2021)

Metabolomics Intervention Towards Better Understanding of Plant Traits.

Cells, 10(2):.

The majority of the most economically important plant and crop species are enriched with the availability of high-quality reference genome sequences forming the basis of gene discovery which control the important biochemical pathways. The transcriptomics and proteomics resources have also been made available for many of these plant species that intensify the understanding at expression levels. However, still we lack integrated studies spanning genomics-transcriptomics-proteomics, connected to metabolomics, the most complicated phase in phenotype expression. Nevertheless, for the past few decades, emphasis has been more on metabolome which plays a crucial role in defining the phenotype (trait) during crop improvement. The emergence of modern high throughput metabolome analyzing platforms have accelerated the discovery of a wide variety of biochemical types of metabolites and new pathways, also helped in improving the understanding of known existing pathways. Pinpointing the causal gene(s) and elucidation of metabolic pathways are very important for development of improved lines with high precision in crop breeding. Along with other -omics sciences, metabolomics studies have helped in characterization and annotation of a new gene(s) function. Hereby, we summarize several areas in the field of crop development where metabolomics studies have made its remarkable impact. We also assess the recent research on metabolomics, together with other omics, contributing toward genetic engineering to target traits and key pathway(s).

RevDate: 2021-10-13
CmpDate: 2021-10-13

Pirhanov A, Bridges CM, Goodwin RA, et al (2021)

Optogenetics in Sinorhizobium meliloti Enables Spatial Control of Exopolysaccharide Production and Biofilm Structure.

ACS synthetic biology, 10(2):345-356.

Microorganisms play a vital role in shaping the soil environment and enhancing plant growth by interacting with plant root systems. Because of the vast diversity of cell types involved, combined with dynamic and spatial heterogeneity, identifying the causal contribution of a defined factor, such as a microbial exopolysaccharide (EPS), remains elusive. Synthetic approaches that enable orthogonal control of microbial pathways are a promising means to dissect such complexity. Here we report the implementation of a synthetic, light-activated, transcriptional control platform using the blue-light responsive DNA binding protein EL222 in the nitrogen fixing soil bacterium Sinorhizobium meliloti. By fine-tuning the system, we successfully achieved optical control of an EPS production pathway without significant basal expression under noninducing (dark) conditions. Optical control of EPS recapitulated important behaviors such as a mucoid plate phenotype and formation of structured biofilms, enabling spatial control of biofilm structures in S. meliloti. The successful implementation of optically controlled gene expression in S. meliloti enables systematic investigation of how genotype and microenvironmental factors together shape phenotype in situ.

RevDate: 2021-10-12

Chipashvili O, Utter DR, Bedree JK, et al (2021)

Episymbiotic Saccharibacteria suppresses gingival inflammation and bone loss in mice through host bacterial modulation.

Cell host & microbe pii:S1931-3128(21)00425-X [Epub ahead of print].

Saccharibacteria (TM7) are obligate epibionts living on the surface of their host bacteria and are strongly correlated with dysbiotic microbiomes during periodontitis and other inflammatory diseases, suggesting they are putative pathogens. However, due to the recalcitrance of TM7 cultivation, causal research to investigate their role in inflammatory diseases is lacking. Here, we isolated multiple TM7 species on their host bacteria from periodontitis patients. These TM7 species reduce inflammation and consequential bone loss by modulating host bacterial pathogenicity in a mouse ligature-induced periodontitis model. Two host bacterial functions involved in collagen binding and utilization of eukaryotic sialic acid are required for inducing bone loss and are altered by TM7 association. This TM7-mediated downregulation of host bacterial pathogenicity is shown for multiple TM7/host bacteria pairs, suggesting that, in contrast to their suspected pathogenic role, TM7 could protect mammalian hosts from inflammatory damage induced by their host bacteria.

RevDate: 2021-10-12

Delgado-García G, Wiebe S, CB Josephson (2021)

The use of patient-reported measures in epilepsy care: the Calgary Comprehensive Epilepsy Program experience.

Journal of patient-reported outcomes, 5(Suppl 2):83.

The regular use of patient-reported measures (PRMs) has been associated with greater patient satisfaction and outcomes. In this article, we will review the Calgary Comprehensive Epilepsy Program's successful experience with PRMs in both clinical and research settings, as well as our current challenges and future directions. Our experience will illustrate that is feasible and convenient to implement PRMs, and especially electronic PRMs (ePRMs), into epilepsy clinics. These PRMs have direct clinical and research applications. They inform clinical decision making through readily interpretable scales to which clinicians can expeditiously respond. Equally, they are increasingly forming an integral and central component of intervention and outcomes-based research. However, implementation studies are necessary to address knowledge gaps and facilitate adoption and dissemination of this approach. A natural symbiosis of the clinical and research realms is precision medicine. The foundations of precision-based interventions are now being set whereby we can maximize the quality of life and psychosocial functioning on an individual level. As illustrated in this article, this exciting prospect crucially depends on the routine use of ePRMs in the everyday care of people with epilepsy. Increasing ePRMs uptake will clearly be a catalyst propelling precision epilepsy from aspiration to clinical reality.

RevDate: 2021-10-12

Sanders WB, BJ Brisky (2021)

Airborne ascospore discharge with co-dispersal of attached epihymenial algae in some foliicolous lichens.

American journal of botany [Epub ahead of print].

PREMISE: Lichen-forming fungi that colonize leaf surfaces must find a compatible algal symbiont, establish lichen symbiosis and reproduce within the limited life span of their substratum. Many produce specialized asexual propagules that appear to be dispersed by rain and runoff currents, but less is known about dispersal of their meiotic ascospores. In some taxa, a layer of algal symbionts covers the hymenial surface of the apothecia, where asci discharge their ascospores. We examined the untested hypothesis that their ascospores are ejected into air currents and carry with them algal symbionts from the epihymenial layer for subsequent lichenization.

METHODS: Leaves bearing the lichens Calopadia puiggarii, Sporopodium marginatum (Pilocarpaceae) and Gyalectidium viride (Gomphillaceae) were collected in southern Florida. The latter two species have epihymenial algal layers. Leaf fragments with apotheciate thalli were affixed in petri dishes, with glass cover slips attached inside the lid over the thalli. Subsequent discharge of ascospores and any co-dispersed algae was evaluated with light microscopy.

RESULTS: All three species discharged ascospores aerially. Discharged ascospores were frequently surrounded by a halo-like sheath of transparent material. In the two species with an epihymenial algal layer, most dispersing ascospores (>90%) co-transported algal cells attached to the spore sheath or wall.

CONCLUSIONS: While water may be the usual vector for their asexual propagules, foliicolous lichen-forming fungi make use of air currents to disperse their ascospores. The epihymenial algal layer represents an adaptation for efficient co-dispersal of the algal symbiont with the next genetic generation of the fungus. This article is protected by copyright. All rights reserved.

RevDate: 2021-10-12

Smith S, Salvato F, Garikipati A, et al (2021)

Activation of the Type VI Secretion System in the Squid Symbiont Vibrio fischeri Requires the Transcriptional Regulator TasR and the Structural Proteins TssM and TssA.

Journal of bacteriology, 203(21):e0039921.

Bacteria have evolved diverse strategies to compete for a niche, including the type VI secretion system (T6SS), a contact-dependent killing mechanism. T6SSs are common in bacterial pathogens, commensals, and beneficial symbionts, where they affect the diversity and spatial structure of host-associated microbial communities. Although T6SS gene clusters are often located on genomic islands (GIs), which may be transferred as a unit, the regulatory strategies that promote gene expression once the T6SS genes are transferred into a new cell are not known. We used the squid symbiont Vibrio fischeri to identify essential regulatory factors that control expression of a strain-specific T6SS encoded on a GI. We found that a transcriptional reporter for this T6SS is active only in strains that contain the T6SS-encoding GI, suggesting the GI encodes at least one essential regulator. A transposon screen identified seven mutants that could not activate the reporter. These mutations mapped exclusively to three genes on the T6SS-containing GI that encode two essential structural proteins (a TssA-like protein and TssM) and a transcriptional regulator (TasR). Using T6SS reporters, reverse transcription-PCR (RT-PCR), competition assays, and differential proteomics, we found that all three genes are required for expression of many T6SS components, except for the TssA-like protein and TssM, which are constitutively expressed. Based on these findings, we propose a model whereby T6SS expression requires conserved structural proteins, in addition to the essential regulator TasR, and this ability to self-regulate may be a strategy to activate T6SS expression upon transfer of T6SS-encoding elements into a new bacterial host. IMPORTANCE Interbacterial weapons like the T6SS are often located on mobile genetic elements, and their expression is highly regulated. We found that two conserved structural proteins are required for T6SS expression in Vibrio fischeri. These structural proteins also contain predicted GTPase and GTP binding domains, suggesting their role in promoting T6SS expression may involve sensing the energetic state of the cell. Such a mechanism would provide a direct link between T6SS activation and cellular energy levels, providing a "checkpoint" to ensure the cell has sufficient energy to build such a costly weapon. Because these regulatory factors are encoded within the T6SS gene cluster, they are predicted to move with the genetic element to activate T6SS expression in a new host cell.

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In the early 1990's, Robert Robbins was a faculty member at Johns Hopkins, where he directed the informatics core of GDB — the human gene-mapping database of the international human genome project. To share papers with colleagues around the world, he set up a small paper-sharing section on his personal web page. This small project evolved into The Electronic Scholarly Publishing Project.

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In 1995, Robbins became the VP/IT of the Fred Hutchinson Cancer Research Center in Seattle, WA. Soon after arriving in Seattle, Robbins secured funding, through the ELSI component of the US Human Genome Project, to create the original ESP.ORG web site, with the formal goal of providing free, world-wide access to the literature of classical genetics.

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Usage of the site grew rapidly and has remained high. Faculty began to use the site for their assigned readings. Other on-line publishers, ranging from The New York Times to Nature referenced ESP materials in their own publications. Nobel laureates (e.g., Joshua Lederberg) regularly used the site and even wrote to suggest changes and improvements.

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Early support from the DOE component of the Human Genome Project was critically important for getting the ESP project on a firm foundation. Since that funding ended (nearly 20 years ago), the project has been operated as a purely volunteer effort. Anyone wishing to assist in these efforts should send an email to Robbins.

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Biographical information about many key scientists.

Selected Bibliographies

Bibliographies on several topics of potential interest to the ESP community are now being automatically maintained and generated on the ESP site.

ESP Picks from Around the Web (updated 07 JUL 2018 )