Temperature-Regulated IncX3 Plasmid Characteristics and the Role of Plasmid-Encoded H-NS in Thermoregulation

Carbapenem-resistant Enterobacteriaceae (CRE) are a critical public health problem worldwide. Globally, IncX3-type plasmids have emerged as the predominant vehicles carrying the metallo-β-lactamase gene blaNDM. Although blaNDM-bearing IncX3 plasmids have been found in various hosts from diverse environments, whether their transfer and persistence properties vary under different conditions and what factors influence any variation is unknown. By observing the effects of different temperatures on IncX3 plasmid conjugation rates, stability, and effects on host fitness in Escherichia coli, we demonstrate that temperature is an important determinant of plasmid phenotypes. The IncX3 plasmid pGZIncX3 transferred at highest frequencies, was most stable and imposed lower fitness costs at 37°C. Temperature-regulated variation in pGZIncX3 properties involved a thermoregulated plasmid-encoded H-NS-like protein, which was produced at higher levels at 30°C and 42°C and inhibited the expression of type IV secretion system genes involved in conjugation. These findings suggest that blaNDM-bearing IncX3 plasmids are adapted to carriage by enterobacteria that colonize mammalian hosts and could explain the rapid dissemination of these plasmids among human-associated species, particularly in hospital settings.

Towards transboundary networks of climate-smart marine reserves in the Southern California Bight

Climate-smart conservation addresses the vulnerability of biodiversity to climate change impacts but may require transboundary considerations. Here, we adapt and refine 16 biophysical guidelines for climate-smart marine reserves for the transboundary California Bight ecoregion. We link several climate-adaptation strategies (e.g., maintaining connectivity, representing climate refugia, and forecasting effectiveness of protection) by focusing on kelp forests and associated species. We quantify transboundary larval connectivity along ~800 km of coast and find that the number of connections and the average density of larvae dispersing through the network under future climate scenarios could decrease by ~50%, highlighting the need to protect critical steppingstone nodes. We also find that although focal species will generally recover with 30% protection, marine heatwaves could hinder subsequent recovery in the following 50 years, suggesting that protecting climate refugia and expanding the coverage of marine reserves is a priority. Together, these findings provide a first comprehensive framework for integrating climate resilience for networks of marine reserves and highlight the need for a coordinated approach in the California Bight ecoregion.

Thermophysical and Transport Properties of the BaCl2-CsCl High Temperature Ionic Liquid Mixtures

High temperature ionic liquids (HTILs) densities and transport properties for mixtures BaCl2‑CsCl, x(BaCl2) = 0-1, have been studied as a function of composition and temperature. In terms of Arrhenius theory, the temperature correlation of all measured properties was made and discussed. Thermodynamic properties (isothermal compressibility, molecular volume, lattice energy, heat capacity, molar Gibbs energy, enthalpy and entropy) were derived for all the studied HTILs from experimental data. The viscosity isotherms show negative deviations from linearity, while conductivity isotherms have positive deviations which may be related to the formation of highly negative changed ion associated species. The evolution of the excess quantities: viscosity deviation (Δη), excess molar viscosity (ΔEη), excess molar conductivity (ΔEκ), show a very good parallelism. The linear behavior between conductivity and viscosity was determined using the fractional Walden rule and the average slope was found far from unity.

Relationship Between Riparian Buffers and Terrestrial Wildlife in the Eastern United States

When working forest stands are harvested, vegetated strips along streams are often retained as part of forestry best management practices (BMPs) to protect water quality. These riparian buffers, known as streamside management zones, when following forestry BMP recommendations, also likely provide benefits to various terrestrial wildlife species. To better understand the role of riparian buffers in contributing to biological diversity in working forest landscapes, we reviewed literature (n = 30) that reported on herpetofauna, bird, and mammal responses to riparian buffers in the eastern United States. Although few results were consistent among taxa, community composition commonly varied among riparian buffer widths. Narrower riparian buffers more commonly supported edge and disturbance-associated species whereas wider riparian buffers tended to support interior-associated species. We did not find a consistent width that supported all terrestrial wildlife species studied. Study Implications: Based on our findings, it may be most efficacious to use varying riparian buffer widths across a landscape to provide structural conditions for a diversity of wildlife species. Some interior species may be best conserved on older managed stands or other retained areas in the landscape rather than riparian buffers. Landscape context and functionality of riparian buffers as movement corridors need to be further investigated, as this is an assumed but not quantified indirect benefit for various terrestrial wildlife species and perhaps especially important for species with low vagility or low dispersal ability that require older forest or riparian areas.

Morphometric Analysis as a Tool to Resolve a Taxonomic Complex in Myrcia sect. Calyptranthes (Myrtaceae, Myrteae)

Abstract— Specimens attributed to Myrcia chytraculia and associated species form a complex within M. sect. Calyptranthes, occurring sympatrically throughout the Caribbean and Central America and sharing a continuously variable suite of morphometric traits. To ascertain whether species within this complex should be treated as separate or conspecific taxa, seven morphometric traits and a further two discrete characters are analysed using univariate and multivariate statistics. Leaf size and shape are found to be indicative of subspecies, and significant mean differences of traits can be found between groups, though they overlap throughout the range of the M. chytraculia complex. As a result of these findings, updated taxonomy for this group is proposed, creating the new combinations Myrcia chytraculia var. americana, Myrcia chytraculia var. pauciflora, and M. chytraculia var. zuzygium, as well as seven new synonyms. A distribution map and a key to the new varieties are also included.

Comparison of the Human Gut Microbiota between Normal Control Subjects and Patients with Colonic Polyps and Colorectal Cancer

Background: The human gut microbiota has been related to numerous colonic diseases. To identify colorectal cancer (CRC)-associated microbiota, the gut microbiomes of patients with colonic polyps and CRC compared to normal controls were analyzed.Methods: Between July and December 2020, forty-four stool samples were obtained from participants older than 50 years who were scheduled for elective colonoscopies at the Surgery Clinic, Songklanagarind Hospital. The samples were divided into 3 groups (17 normal control, 17 colonic polyps, and 10 CRC) and were collected for analysis with a 16s metagenomic sequencing library preparation with MiSeq Reporter software (MSR) following the protocol of the 16s metagenomics workflow. The microbiome data were analyzed with Kruskal–Wallis test with the Dunn-Bonferroni post hoc method.Results: The relative proportions of beneficial butyrate-producers Kineothrix alysoides, Eubacterium rectale, and Roseburia inulinsivorans were significantly higher in healthy control and colonic polyp groups compared with the CRC group at the top three lowest p-values. The recommended CRC biomarker Clostridium symbiosum was shown in a significantly higher proportion in the CRC group than in the normal control group. The prevalences and relative proportion of the novel CRC-associated species Acutalibacter muris and the familiar CRC-associated species Christensenella massiliensis and lntestinimonas butyriciproducens were significantly higher in the CRC group than in the normal control and colonic polyp groups at the top three lowest p-values.Conclusions: A correlation between specific bacteria and clinical outcomes was found in this pilot study. The microbiome data revealed possible microbial biomarkers associated with CRC. Studies with larger numbers of stool samples are required to substantiate our findings.

Chemical and Behavioural Strategies along The Spectrum of Host Specificity in Ant-Associated Silverfish

Background Host range is a fundamental trait to understand the ecological and evolutionary dynamics of symbionts. Increasing host specificity is expected to be accompanied with specialization in different symbiont traits. We tested this specificity-specialization association in a large group of 16 ant-associated silverfish species by linking their level of host specificity with their degree of behavioural integration into the colony and their accuracy of chemically deceiving the host’s recognition system, i.e. the cuticular hydrocarbon (CHC) profile. Results As expected, facultative associates and host generalists (targeting multiple unrelated ants) tend to avoid the host, whereas host-specialists (typically restricted to Messor ants) were bolder, approached the host and allowed inspection. Generalists and host specialists regularly followed a host worker, unlike the other silverfish. Host aggression was extremely high toward non-ant-associated silverfish and modest to low in ant-associated groups. Surprisingly, the degree of chemical deception was not linked with host specificity as most silverfish, including facultative ant associates, imitated the host’s CHC profile. Messor specialists retained the same CHC profile as the host after moulting, in contrast to a host generalist, suggesting an active production of the cues (chemical mimicry). Host generalist and facultative associates flexibly copied the highly different CHC profiles of alternative host species, pointing at passive acquisition (chemical camouflage) of the host’s odour. Conclusions Overall, we found that behaviour that seems to facilitate the integration in the host colony was more pronounced in host specialist silverfish. Chemical deception, however, was employed by all ant-associated species, irrespective of their degree of host specificity.

Disturbance and distribution gradients influence resource availability and feeding behaviours in corallivore fishes following a warm-water anomaly

Understanding interactions between spatial gradients in disturbances, species distributions and species’ resilience mechanisms is critical to identifying processes that mediate environmental change. On coral reefs, a global expansion of coral bleaching is likely to drive spatiotemporal pulses in resource quality for obligate coral associates. Using technical diving and statistical modelling we evaluated how depth gradients in coral distribution, coral bleaching, and competitor density interact with the quality, preference and use of coral resources by corallivore fishes immediately following a warm-water anomaly. Bleaching responses varied among coral genera and depths but attenuated substantially between 3 and 47 m for key prey genera (Acropora and Pocillopora). While total coral cover declined with depth, the cover of pigmented corals increased slightly. The abundances of three focal obligate-corallivore butterflyfish species also decreased with depth and were not related to spatial patterns in coral bleaching. Overall, all species selectively foraged on pigmented corals. However, the most abundant species avoided feeding on bleached corals more successfully in deeper waters, where bleaching prevalence and conspecific densities were lower. These results suggest that, as coral bleaching increases, energy trade-offs related to distributions and resource acquisition will vary with depth for some coral-associated species.

A Deep Learning Model to Recognize and Quantitatively Analyze Cold Seep Substrates and the Dominant Associated Species

Characterizing habitats and species distribution is important to understand the structure and function of cold seep ecosystems. This paper develops a deep learning model for the fast and accurate recognition and classification of substrates and the dominant associated species in cold seeps. Considering the dense distribution of the dominant associated species and small objects caused by overlap in cold seeps, the feature pyramid network (FPN) embed into the faster region-convolutional neural network (R-CNN) was used to detect large-scale changes and small missing objects without increasing the number of calculations. We applied three classifiers (Faster R-CNN + FPN for mussel beds, lobster clusters and biological mixing, CNN for shell debris and exposed authigenic carbonates, and VGG16 for reduced sediments and muddy bottom) to improve the recognition accuracy of substrates. The model’s results were manually verified using images obtained in the Formosa cold seep during a 2016 cruise. The recognition accuracy of the two dominant species, e.g., Gigantidas platifrons and Munidopsidae could be 70.85 and 56.16%, respectively. Seven subcategories of substrates were also classified with a mean accuracy of 74.87%. The developed model is a promising tool for the fast and accurate characterization of substrates and epifauna in cold seeps, which is crucial for large-scale quantitative analyses.

Sargassum Differentially Shapes the Microbiota Composition and Diversity at Coastal Tide Sites and Inland Storage Sites on Caribbean Islands

Rafts of drifting pelagic Sargassum that are circulating across the Atlantic Ocean are complex ecosystems composed of a large number of associated species. Upon massive stranding, they lead to various socio-environmental issues including the inflow of contaminants and human health concerns. In this study, we used metabarcoding approaches to examine the differences in both the eukaryotic- and prokaryotic-associated communities from Sargassum present in two islands of the Lesser Antilles, namely Guadeloupe and Martinique. We detected significant differences in microbial community structure and composition between landing Sargassum, the surrounding seawater, and Sargassum from inland storage sites. In total we identified 22,214 prokaryotic and 17,679 eukaryotic OTUs. Among them, functional prediction analyses revealed a number of prokaryotes that might contribute to organic matter decomposition, nitrogen cycling and gas production, including sulfate-reducing bacteria at coastal landing sites, and methanogenic archaea at inland storage sites. We also found that Metazoan was the most abundant group in Sargassum samples, with nematode clades that presented exclusive or specific richness and abundance patterns depending on their Sargassum substrate. Together, these molecular inventories of the micro- and meiofauna communities provide baseline information for further characterization of trophic interactions, algal organic matter decomposition and nutrient transfers at coastal and inland storage sites.