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Stony coral tissue loss disease (SCTLD) affects at least 22 Western Atlantic coral species and presents as focal or multifocal lesions, which swiftly expand across the colony, resulting in rapid tissue loss and mortality. Previous histopathological examinations have noted necrosis, body wall breakage, gastrodermal separation, exocytosis, and vacuolization of the symbiont as pathological signs; however, the same signs are present to some degree in otherwise apparently healthy coral tissues processed for histology. Here, we quantify the degree of symbiont vacuolization, symbiont size change, exocytosis, and gastrodermal separation in apparently healthy and diseased coral tissues of eight coral species in association with SCTLD transmission experiments in Florida (USA) and the United States Virgin Islands. We describe a characteristic progression of disease signs which support the hypothesis that coral-algal dysbiosis contributes to SCTLD-associated tissue loss. Progression begins with symbiont cell vacuolization, followed by symbiont cell exocytosis and gastrodermal cell lysis. The lysing of gastrodermal cells leads to separation of the gastrodermis from the mesoglea, and finally to liquifying necrosis. Disease signs varied by coral species and symbiont genus following known hierarchy in disease susceptibility across coral and algal genera. SCTLD histological dynamics were also associated with differential expression of genes considered indicative of stress and dysbiosis and further influenced by both coral species and algal symbiont genus. 

Bacterial species within the mammalian gut microbiota exhibit considerable strain diversity associated with both geography and host genetic ancestry. However, because geography and ancestry are typically confounded, disentangling their contributions to the divergence of gut bacterial strains has remained challenging. Here we show that isolation by distance (IBD) promotes gut bacterial strain divergence within host species independently of host ancestry. Joint profiling of gut bacterial and mitochondrial genomes from wild-living populations of deer mice (Peromyscus maniculatus) sampled across the USA revealed significant IBD in 27 predominant gut bacterial species, including Muribaculaceae and Lachnospiraceae spp., but limited evidence for co-inheritance of gut bacterial genomes with mitochondria during the diversification of mouse populations. Spore-forming gut bacterial species exhibited reduced IBD, suggesting that adaptations facilitating bacterial dispersal can lessen geographic structuring of strain diversity. In contrast to conspecific hosts sampled at the same field site, hosts of different rodent genera sampled in sympatry with deer mice harboured divergent strains within shared gut bacterial species. These results indicate that geographic distance mediates the early stages of gut bacterial strain divergence between conspecific hosts, whereas effects of host ancestry on strain-level microbiota composition emerge over longer evolutionary timescales, such as those separating host genera. 

Evidence is mounting that rapid environmental change threatens global insect biodiversity, underscoring the need for informed conservation strategies that protect both species and the ecosystem services they provide. Armed with accurate baseline community data, long‐term continental‐scale monitoring projects are invaluable for detecting and predicting responses to ecological change. However, high species diversity and temporal variability in population sizes can hinder our ability to establish baselines, and, thus, obscure, exaggerate, or reverse temporal trends in long‐term insect data. With its scale and consistent protocol, the US National Ecological Observatory Network (NEON) carabid pitfall trapping data provides an excellent case study for evaluating sampling effort. We use species incidence‐frequencies calculated from more than 200 000 identified carabids across up to 10 years of sampling and 46 field sites to extrapolate asymptotic richness and Shannon diversity. We find that the completeness of observed species richness and diversity is negatively related to year‐to‐year species turnover and diversity metrics themselves, but improves with increasing sampling duration. While observed Shannon diversity converges to asymptotic estimates within a few years, we find that NEON's intensive sampling is unlikely to capture all species, even if no biodiversity loss occurs over its 30‐year span. If the mechanisms driving these patterns can be understood, they hold important implications for optimizing sampling designs in studies focused on ecological change detection, particularly for diverse and temporally variable taxa. Our findings underscore the critical importance of long‐term monitoring and prompt reconsideration of how we interpret trends in existing biodiversity data, given the complexity of establishing robust baselines. 

Abstract Anthropogenic climate change has had devastating effects on the Florida and Caribbean reef systems, in part due to increased disease outbreaks. Climate change exacerbates marine diseases by expanding pathogen ranges and heightening host susceptibility through environmental stress. Specifically, there has been a stark rise in marine disease events outbreaks targeting multiple coral species, resulting in high mortality rates and declining reef biodiversity. Although many of these diseases present similar visual symptoms, they exhibit varying mortality rates and require distinct treatment protocols. Advances in coral transcriptomics research have enhanced our understanding of coral responses to various diseases, but more sophisticated methods are required to classify diseases that appear visually similar. This study provides the first machine learning (ML) model that can classify two common coral diseases: stony coral tissue loss disease (SCTLD) and white plague (WP). Using various algorithms, 463 gene expression biomarkers were identified, with 275 unique to SCTLD and 167 unique to WP, revealing distinct immune responses between the two diseases. The final ML model was built with partial least squares discriminant analysis (PLS-DA) and the identified biomarkers were tested and validated with samples collected in situ. It achieved high predictive performance, with an Area Under the Receiver Operating Characteristic (ROC) Curve (AUC) of 0.9895, an average overall error rate of 0.0754, and an average balanced error rate (BER) of 0.0799. This study provides a preliminary disease classification model that reliably distinguishes between SCTLD and WP and offers valuable insights into their underlying cellular responses. Additionally, the identified biomarkers provide a foundation for the development of rapid diagnostic tools to identify and mitigate future coral disease outbreaks. 

Abstract BackgroundLongitudinal skeletal growth takes place in the cartilaginous growth plates. While growth plates are found at either end of conventional long bones, they occur at a variety of locations in the mammalian skeleton. For example, the metacarpals and metatarsals (MT) in the hands and feet form only a single growth plate at one end, and the pisiform in the wrist is the only carpal bone to contain a growth plate. We take advantage of this natural anatomical variation to test which components of the PTHrP/Ihh feedback loop, a fundamental regulator of chondrocyte differentiation, are specific to growth plate function. ResultsParathyroid hormone‐like hormone(Pthlh), the gene that transcribes parathyroid hormone‐related peptide (PTHrP), is expressed in the reserve zone of the growth plate‐forming end of the MT. At the opposite end, the absence of a PTHrP+ reserve zone results in premature chondrocyte differentiation andIndian hedgehog(Ihh) expression.Pthlhis expressed in the reserve zone of the developing pisiform, confirming the existence of a true growth plate. ConclusionA pool of PTHrP+ reserve zone chondrocytes is a defining characteristic of growth plates, and its patterning may be key to evolved differences in growth plate location in the mammalian skeleton. 

ABSTRACT We observed a novel, nocturnal cleaning interaction between a cleaner shrimp (GenusUrocaridella) and the giant moray eel (Gymnothorax javanicus) on a lagoonal patch reef in Moorea, French Polynesia. Over the course of an 85‐min foraging bout (recorded on video by a snorkeler), we observed three separate, stereotyped cleaning interactions betweenG. javanicusand a cleaner shrimp in the genus Urocaridella (which surveys of Moorea biodiversity previously visually identified asUrocaridella antonbruunii). During these interactions, the shrimp would slowly crawl along one of the eel's flanks towards its head, enter its mouth, emerge on the other side of its head, then crawl back towards the reef along the eel's opposite flank, often causing it to jolt in response. On each of the visits, the moray spent roughly 9–12 min at the cleaning station and was observed being cleaned for a total of 62 s. Although this was a chance observation of only a few instances of cleaning, it may have several important implications for our understanding of the behavioral ecology of cleaning mutualisms, including (1) indicating potential temporal trade‐offs between being cleaned and foraging in eels, (2) suggesting a degree of temporal niche partitioning among sympatric cleaner species and (3) updating our understanding of cleaner‐client communication, given the nocturnal nature of our observations. 

This work describes the effect of varying crosslink density and plasticizer loading on covalent adaptable networks that have equal amounts of reactive functionalities. 

Fluid flows are dominant features of many bacterial environments, and flow can often impact bacterial behaviors in unexpected ways. For example, the most common type of cardiovascular infection is heart valve colonization by gram-positive bacteria likeStaphylococcus aureusandEnterococcus faecalis(endocarditis). This behavior is counterintuitive because heart valves experience high shear rates that would naively be expected to reduce colonization. To determine whether these bacteria preferentially colonize higher shear rate environments, we developed a microfluidic system to quantify the effect of flow conditions on the colonization ofS. aureusandE. faecalis. We find that the preferential colonization in high flow of both species is not specific to heart valves and can be found in simple configurations lacking any host factors. This behavior enables bacteria that are outcompeted in low flow to dominate in high flow. Surprisingly, experimental and computational studies reveal that the two species achieve this behavior via distinct mechanisms.S. aureusgrows in cell clusters and produces a dispersal signal whose transport is affected by shear rate. Meanwhile,E. faecalisgrows in linear chains whose mechanical properties result in less dispersal in the presence of higher shear force. In addition to establishing two divergent mechanisms by which these bacteria each preferentially colonize high-flow environments, our findings highlight the importance of understanding bacterial behaviors at the level of collective interactions among cells. These results suggest that distinct multicellular nanocolony morphologies have previously unappreciated costs and benefits in different environments, like those introduced by fluid flow.