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Venom is a known source of novel antimicrobial natural products. The substantial, increasing number of these discoveries have unintentionally culminated in the misconception that venom and venom-producing glands are largely sterile environments. Culture-dependent and -independent studies on the microbial communities in venom microenvironments reveal the presence of archaea, algae, bacteria, fungi, protozoa, and viruses. Venom-centric microbiome studies are relatively sparse to date with the adaptive advantages that venom-associated microbes might offer to their hosts, or that hosts might provide to venom-associated microbes, remaining largely unknown. We highlight the potential for the discovery of venom microbiomes within the adaptive landscape of venom systems. The considerable number of convergently evolved venomous animals, juxtaposed with the comparatively few known studies to identify microbial communities in venom, provides new possibilities for both biodiversity and therapeutic discoveries. We present an evidence-based argument for integrating microbiology as part of venomics (i.e., venom-microbiomics) and introduce iVAMP, the Initiative for Venom Associated Microbes and Parasites (https://ivamp-consortium.github.io/), as a growing collaborative consortium. We express commitment to the diversity, inclusion and scientific collaboration among researchers interested in this emerging subdiscipline through expansion of the iVAMP consortium.

Background: The observed growth variability of different aquaculture species in captivity hinders its large-scale production. For the sandfish Holothuria scabra, a tropical sea cucumber species, there is a scarcity of information on its intestinal microbiota in relation to host growth, which could provide insights into the processes that affect growth and identify microorganisms with probiotic or biochemical potential that could improve current production strategies. To address this gap, this study used 16 S rRNA amplicon sequencing to characterize differences in gut and fecal microbiota among large and small juveniles reared in floating ocean nurseries. Results: We recovered 5915 amplicon sequence variants and diversity indices revealed significant differences between large and small juveniles (p < 0.05). Gut microbiota of large juveniles had lower bacterial diversity than its smaller counterparts. The genus cluster Burkholderia-Caballeronia-Paraburkholderia (BCP) is the most common and abundant taxa found in the gut for both size categories but less abundant in fecal samples. Small juveniles had a higher abundance of members from the Roseobacter clade (Rhodobacteriaceae) such as Ruegeria, Shimia, Psuedoruegeria and Marivita among others while the genus Schlegelella (Caldimonas) and Bosea were primarily found in larger juveniles. Predicted physiological functions identified signatures of metabolism, biosynthesis, and biodegradation pathways unique for each size category. Significant differences in diversity and composition were also exhibited between the pooled fecal and gut sample types. Conclusions: The bacterial composition in the intestinal tract of the sandfish H. scabra is an important factor in the observed growth variability in aquaculture. The results show differences in diversity, composition and predicted physiological functions between the size groups, despite being from the same cohort and environment. It was also evident that the fecal microbiota differs from the gut and does not correspond to size category, warranting caution in using the fecal matter as a proxy to infer microbial composition and interactions in the gastrointestinal tract. Understanding the roles that these microorganisms play in sandfish growth could support the development of strategies to manage size variation in captive-bred sea cucumbers, or for the promotion and selection for faster-growing individuals. [ABSTRACT FROM AUTHOR]

Estuarine organisms, such as the model cnidarian the starlet sea anemone (Nematostella vectensis), experience daily variation in their marine environment. The adaptability of N. vectensis can be attributed not only to genetic recombination and natural selection, but potentially to DNA methylation, an heritable and reversible change in DNA expression where a methyl group is added to the five-position carbon on a cytosine ring to alternate gene expression in response to environment changes. This study focuses on understanding microbial metabolite interactions from Bacillus thuringiensis with N. vectensis using the solution containing secreted metabolites from bacterial growth known as cell-free supernatant (CFS). We examined larval development and methylation rates of adult polyp genes. For both experiments, larvae or adult N. vectensis were placed into a 0.5% concentration of CFS for a week. The larvae were observed to determine life stage progression at various time points, and adult N. vectensis had their DNA extracted after exposure. Examining larval development, development time was not affected by the presence of CFS. Analyzing the methylation of genes in adult N. vectensis, a total of 23 differentially methylated genes were noted. Multiple genes were identified as having unknown functions, being uncharacterized, or were pseudogenes. Genes that did present a function were functions related to cell wall integrity & stress response, ubiquitin-like-specific protease, and tRNAs. Genome methylation showed similar groupings of methylated genes between sexes rather than treatment types. Overall, our work provides insight into the role of CFS within estuarine environments and its potential effects on marine invertebrate survival. [ABSTRACT FROM AUTHOR]

BackgroundThe non-migratory killifish Fundulus heteroclitus inhabits clean and polluted environments interspersed throughout its range along the Atlantic coast of North America. Several populations of this species have successfully adapted to environments contaminated with toxic aromatic hydrocarbon pollutants such as polychlorinated biphenyls (PCBs). Previous studies suggest that the mechanism of resistance to these and other "dioxin-like compounds" (DLCs) may involve reduced signaling through the aryl hydrocarbon receptor (AHR) pathway. Here we investigated gene diversity and evidence for positive selection at three AHR-related loci (AHR1, AHR2, AHRR) in F. heteroclitus by comparing alleles from seven locations ranging over 600 km along the northeastern US, including extremely polluted and reference estuaries, with a focus on New Bedford Harbor (MA, USA), a PCB Superfund site, and nearby reference sites.ResultsWe identified 98 single nucleotide polymorphisms within three AHR-related loci among all populations, including synonymous and nonsynonymous substitutions. Haplotype distributions were spatially segregated and F-statistics suggested strong population genetic structure at these loci, consistent with previous studies showing strong population genetic structure at other F. heteroclitus loci. Genetic diversity at these three loci was not significantly different in contaminated sites as compared to reference sites. However, for AHR2 the New Bedford Harbor population had significant FST values in comparison to the nearest reference populations. Tests for positive selection revealed ten nonsynonymous polymorphisms in AHR1 and four in AHR2. Four nonsynonymous SNPs in AHR1 and three in AHR2 showed large differences in base frequency between New Bedford Harbor and its reference site. Tests for isolation-by-distance revealed evidence for non-neutral change at the AHR2 locus.ConclusionTogether, these data suggest that F. heteroclitus populations in reference and polluted sites have similar genetic diversity, providing no evidence for strong genetic bottlenecks for populations in polluted locations. However, the data provide evidence for genetic differentiation among sites, selection at specific nucleotides in AHR1 and AHR2, and specific AHR2 SNPs and haplotypes that are associated with the PCB-resistant phenotype in the New Bedford Harbor population. The results suggest that AHRs, and especially AHR2, may be important, recurring targets for selection in local adaptation to dioxin-like aromatic hydrocarbon contaminants.

Morphological plasticity is an adaptive response to heterogenous environments when a fitness advantage is conferred. Larval sea urchins, for example, are hypothesized to increase individual fitness in dilute feeding environments by elongating their feeding structure relative to their body size. Morphological plasticity for larval sea urchins is also coupled with significant shifts in the associated bacterial community, but whether this change to the associated microbiota occurs before, during, or following the expression of morphological plasticity is unclear. Using the sea urchin Lytechinus variegatus, we compare the temporal pattern of the microbial community and how it relates to the timing of morphological plasticity for larvae cultured in different food concentrations. From prefeeding through the expression of morphological plasticity, we observed that the microbiota associated with L. variegatus larvae exhibit a four-stage successional pattern, where changes in this community shift prior to the expression of the environment-specific morphology. The high food treatment, which results in the short-arm phenotype, deviated from the microbial trajectory of larval siblings prior to measurable morphological plasticity. These data suggest that a holobiont may exhibit shifts in the associated bacterial community corresponding with variation in the feeding environment that could occur in anticipation of or prior to morphological plasticity., Author(s): Tyler J. Carrier [sup.1], Adam M. Reitzel [sup.1] Author Affiliations: (1) 0000 0000 8598 2218, grid.266859.6, Department of Biological Sciences, University of North Carolina, , Charlotte, NC, USA Introduction [...]