Effects of acute exposures of 2,4,6-trinitrotoluene and inorganic lead on the fecal microbiome of the green anole (Anolis carolinensis)

Comparative Analyses of Lycodon rufozonatus and Lycodon rosozonatus Gut Microbiota in Different Regions

The interactions between hosts and the gut microbiota are intricate and can significantly affect the ecology and evolution of both parties. Various host traits, including taxonomy, diet, social behaviour, and external factors such as prey availability and the local environment, all play an important role in shaping composition and diversity of the gut microbiogta. In this study, we explored the impact of intestinal microorganisms on the host in adapting to their respective ecological niches in two species of snakes. We collected feces from Lycodon rufozonatus and Lycodon rosozonatus from different geographical locations and used 16S rRNA gene sequencing technology to sequence the v3-v4 region. The results revealed that there was no significant difference in the alpha diversity of intestinal microorganisms between L. rufozonatus and L. rosozonatus. The gut microbiota of all individuals comprised four main phyla: Pseudomonadota, Bacteroidota, Bacillota, and Actinomycetota. At the genus level, the genus Salmonella dominated the enterobacterial microbiota in the samples from Hainan, while there was no obvious dominant genus in the enterobacterial microbiota of the samples from the other four localities. Comparative analysis of enzyme families annotated to the gut microbiota between L. rufozonatus and L. rosozonatus from the four sampling regions by CAZy carbohydrate annotation revealed that nine enzyme families differed significantly in terms of glycoside hydrolases (GHs). In addition, we compared the composition of gut microbial communities between L. rufozonatus and L. rosozonatus and investigated the impact of the differences on their functions. Our results will provide insights into the coevolution of host and gut microbes.

Gut microbiome of the sole surviving member of reptile order Rhynchocephalia reveals biogeographic variation, influence of host body condition and a substantial core microbiota in tuatara across New Zealand

Tuatara are the sole extant species in the reptile order Rhynchocephalia. They are ecologically and evolutionarily unique, having been isolated geographically for ~84 million years and evolutionarily from their closest living relatives for ~250 million years. Here we report the tuatara gut bacterial community for the first time. We sampled the gut microbiota of translocated tuatara at five sanctuaries spanning a latitudinal range of ~1000 km within Aotearoa New Zealand, as well as individuals from the source population on Takapourewa (Stephens Island). This represents a first look at the bacterial community of the order Rhynchocephalia and provides the opportunity to address several key hypotheses, namely that the tuatara gut microbiota: (1) differs from those of other reptile orders; (2) varies among geographic locations but is more similar at sites with more similar temperatures and (3) is shaped by tuatara body condition, parasitism and ambient temperature. We found significant drivers of the microbiota in sampling site, tuatara body condition, parasitism and ambient temperature, suggesting the importance of these factors when considering tuatara conservation. We also derived a 'core' community of shared bacteria across tuatara at many sites, despite their geographic range and isolation. Remarkably, >70% of amplicon sequence variants could not be assigned to known genera, suggesting a largely undescribed gut bacterial community for this ancient host species.

16S rRNA gene-based meta-analysis of the reptile gut microbiota reveals environmental effects, host influences and a limited core microbiota

An animal's gut microbiota plays an important role in host health, reproduction and digestion. However, many studies focus on only a few individuals or a single species, limiting our ability to recognize emergent patterns across a wider taxonomic grouping. Here, we compiled and reanalysed published 16S rRNA gene sequence data for 745 gut microbiota samples from 91 reptile species using a uniform bioinformatics pipeline to draw broader conclusions about the taxonomy of the reptile gut microbiota and the forces shaping it. Our meta-analysis revealed the significant differences in alpha- and beta-diversity across host order, environment, diet, habitat and conservation status, with host diet and order contributing the most to these differences. We identified the principal bacterial phyla present in the reptile gut microbiota as Bacteroidota, Proteobacteria (mostly Gamma class), and Firmicutes, and detected the bacterial genus Bacteroides in most reptile individuals, thus representing a putative 'core' microbiota. Our study provides novel insights into key drivers of the reptile gut microbiota, highlights existing knowledge gaps and lays the groundwork for future research on these fascinating hosts and their associated microbes.

Proximate Drivers of Population-Level Lizard Gut Microbial Diversity: Impacts of Diet, Insularity, and Local Environment

Diet has been suggested to be an important driver of variation in microbiota composition in mammals. However, whether this is a more general phenomenon and how fast changes in gut microbiota occur with changes in diet remains poorly understood. Forty-nine years ago, ten lizards of the species Podarcis siculus were taken from the island of Pod Kopište and introduced onto the island of Pod Mrčaru (Croatia). The introduced population underwent a significant dietary shift, and their descendants became omnivorous (consuming up to 80% plant material during summer). Variation in their gut microbiota has never been investigated. To elucidate the possible impact on the gut microbiota of this rapid change in diet, we compared the microbiota (V4 region of the 16S rRNA gene) of P. siculus from Pod Mrčaru, Pod Kopište, and the mainland. In addition, we explored other drivers of variation in gut microbiota including insularity, the population of origin, and the year of sampling. Alpha-diversity analyses showed that the microbial diversity of omnivorous lizards was higher than the microbial diversity of insectivorous lizards. Moreover, omnivorous individuals harbored significantly more Methanobrevibacter. The gut microbial diversity of insectivorous lizards was nonetheless more heterogeneous. Insectivorous lizards on the mainland had different gut microbial communities than their counterparts on the island of Pod Kopište. Bacillus and Desulfovibrio were more abundant in the gut microbiota from insular lizards compared to mainland lizards. Finally, we showed that the population of origin was also an important driver of the composition of the gut microbiota. The dietary shift that occurred in the introduced population of P. siculus has had a detectable impact on the gut microbiota, but other factors such as insularity and the population of origin also contributed to differences in the gut microbial composition of these lizards, illustrating the multifactorial nature of the drivers of variation in gut microbiota. Overall, our data show that changes in gut microbiota may take place on ecological timescales. Yet, diet is only one of many factors driving variation in gut microbiota across populations.

Hydrazone connected stable luminescent covalent-organic polymer for ultrafast detection of nitro-explosives

Developing promising luminescent probes for the selective sensing of nitro-explosives remains a challenging issue. Porous luminescent covalent–organic polymers are one of the excellent sensing probes for trace hazardous materials. Herein, fluorescent monomers 1,1,2,2-tetrakis(4-formyl-(1,1′-biphenyl))ethane (TFBE) and 1,3,5-benzenetricarboxylic acid trihydrazide (BTCH) were selected to build a novel hydrazone connected stable luminescent covalent–organic polymer (H-COP) of high stability by typical Schiff-base reaction. The N₂ sorption study, BET surface area analysis, and TGA profile indicate the porosity and stability of this H-COP material. Such properties of the H-COP material enable a unique sensing platform for nitro-explosives with great sensitivity (Ksv ∼ 10⁶ M) and selectivity up to μM. This polymer material shows attractive selectivity and sensitivity towards phenolic nitro-explosives and other common explosives among earlier reported COP-based sensors.

A novel H-COP was synthesized through Schiff-base condensation reaction, which shows high sensitivity (K_sv ∼ 10⁶ M⁻¹) and selectivity (μM level) towards nitro-explosives.

Genomic investigations of acute munitions exposures on the health and skin microbiome composition of leopard frog (Rana pipiens) tadpoles

Natural communities of microbes inhabiting amphibian skin, the skin microbiome, are critical to supporting amphibian health and disease resistance. To enable the pro-active health assessment and management of amphibians on Army installations and beyond, we investigated the effects of acute (96h) munitions exposures to Rana pipiens (leopard frog) tadpoles and the associated skin microbiome, integrated with RNAseq-based transcriptomic responses in the tadpole host. Tadpoles were exposed to the legacy munition 2,4,6-trinitrotoluene (TNT), the new insensitive munition (IM) formulation, IMX-101, and the IM constituents nitroguinidine (NQ) and 1-methyl-3-nitroguanidine (MeNQ). The 96h LC50 values and 95% confidence intervals were 2.6 (2.4, 2.8) for ΣTNT and 68.2 (62.9, 73.9) for IMX-101, respectively. The NQ and MeNQ exposures caused no significant impacts on survival in 96h exposures even at maximum exposure levels of 3560 and 5285 mg/L, respectively. However, NQ and MeNQ, as well as TNT and IMX-101 exposures, all elicited changes in the tadpole skin microbiome profile, as evidenced by significantly increased relative proportions of the Proteobacteria with increasing exposure concentrations, and significantly decreased alpha-diversity in the NQ exposure. The potential for direct effects of munitions exposure on the skin microbiome were observed including increased abundance of munitions-tolerant phylogenetic groups, in addition to possible indirect effects on microbial flora where transcriptional responses suggestive of changes in skin mucus-layer properties, antimicrobial peptide production, and innate immune factors were observed in the tadpole host. Additional insights into the tadpole host's transcriptional response to munitions exposures indicated that TNT and IMX-101 exposures significantly enriched transcriptional expression within type-I and type-II xenobiotic metabolism pathways, where dose-responsive increases in expression were observed. Significant enrichment and increased transcriptional expression of heme and iron binding functions in the TNT exposures served as likely indicators of known mechanisms of TNT toxicity including hemolytic anemia and methemoglobinemia. The significant enrichment and dose-responsive decrease in transcriptional expression of cell cycle pathways in the IMX-101 exposures was consistent with previous observations in fish, while significant enrichment of immune-related function in response to NQ exposure were consistent with potential immune suppression at the highest NQ exposure concentration. Finally, the MeNQ exposures elicited significantly decreased transcriptional expression of keratin 16, type I, a gene likely involved in keratinization processes in amphibian skin. Overall, munitions showed the potential to alter tadpole skin microbiome composition and affect transcriptional profiles in the amphibian host, some suggestive of potential impacts on host health and immune status relevant to disease susceptibility.

The gut bacterial microbiota of sea turtles differs between geographically distinct populations

The microbiota of metazoans can be influenced by a variety of factors including diet, environment and genetics. In this study we sampled multiple populations from 2 host species that do not overlap in distribution, in order to test whether their bacterial microbiotas are species-specific or more variable. Intestinal swabs were collected from loggerhead turtles originating from Florida, USA, and Queensland, Australia, as well as from flatback turtles from Crab Island, Queensland, and Port Hedland, Western Australia. We then manually extracted bacterial DNA and used 16S rRNA sequencing to explore bacterial microbial community composition and structure. Our investigation showed that the bacterial microbiota of sea turtles is heavily influenced by geography, with loggerhead turtles originating from the USA and Australia harbouring significantly different bacterial microbial populations in terms of composition. Similarly, we also found that flatback turtles from Crab Island had significantly less diverse microbiotas, with a predominance of the bacterial phylum Firmicutes, in comparison to their genetically similar counterparts from Port Hedland. Factors that may explain these observed differences between populations include host genetics, differences in foraging habitat quality and differences in migratory distance (and thus durations of inappetence) between foraging and breeding grounds. The mechanisms by which these factors may influence bacterial microbial composition of sea turtle gastrointestinal tracts warrants further investigation. The results of this study highlight the importance of interpreting microbiota data of wild animals in the context of geography.

Microbial symbiosis and coevolution of an entire clade of ancient vertebrates: the gut microbiota of sea turtles and its relationship to their phylogenetic history

Background

The microbiota plays a critical role in host homeostasis and has been shown to be a major driving force in host evolution. However, our understanding of these important relationships is hampered by a lack of data for many species, and by significant gaps in sampling of the evolutionary tree. In this investigation we improve our understanding of the host-microbiome relationship by obtaining samples from all seven extant species of sea turtle, and correlate microbial compositions with host evolutionary history.

Results

Our analysis shows that the predominate phyla in the microbiota of nesting sea turtles was Proteobacteria. We also demonstrate a strong relationship between the bacterial phyla SR1 and sea turtle phylogeny, and that sea turtle microbiotas have changed very slowly over time in accordance with their similarly slow phenotypic changes.

Conclusions

This is one of the most comprehensive microbiota studies to have been performed in a single clade of animals and further improves our knowledge of how microbial populations have influenced vertebrate evolution.

Meeting report of the third annual Tri-Service Microbiome Consortium symposium

The Tri-Service Microbiome Consortium (TSMC) was founded to enhance collaboration, coordination, and communication of microbiome research among U.S. Department of Defense (DoD) organizations and to facilitate resource, material and information sharing among consortium members. The 2019 annual symposium was held 22-24 October 2019 at Wright-Patterson Air Force Base in Dayton, OH. Presentations and discussions centered on microbiome-related topics within five broad thematic areas: 1) human microbiomes; 2) transitioning products into Warfighter solutions; 3) environmental microbiomes; 4) engineering microbiomes; and 5) microbiome simulation and characterization. Collectively, the symposium provided an update on the scope of current DoD microbiome research efforts, highlighted innovative research being done in academia and industry that can be leveraged by the DoD, and fostered collaborative opportunities. This report summarizes the presentations and outcomes of the 3rd annual TSMC symposium.