Biology subjects

Paul, V.

Publications and source records attributed to Paul, V..

7 recordsLinked to original sources

bioRxiv2026

Stony coral tissue loss disease outbreak altered reef communities of Carrie Bow Cay, Belize

Stony coral tissue loss disease (SCTLD) has caused one of the most damaging coral epizootics on record, impacting about half of coral species across most of the reef systems of the Caribbean and Florida. To evaluate its impact on the coral reefs surrounding Carrie Bow Cay, Belize, we monitored seven fixed transects before and at two time points during the outbreak using three different methods. We estimated species-specific mortality rates by fate tracking tagged colonies, quantified reef-wide lesion prevalence and resulting changes to colony density and community composition using in situ transect surveys, and finally calculated changes to total coral cover using benthic photoquadrats. SCTLD quickly led to mortality of infected corals. Between October 2019 and May 2022, 32% of the 102 fate-tracked coral colonies had developed lesions consistent with SCTLD and an additional 30% had suffered complete mortality likely due to SCTLD. By December of 2022, 21% of the 33 colonies that had been observed with lesions had died. We documented patterns of species susceptibility largely confirming previous reports in other locations. We documented sharp abundance declines in several species, including the total loss of Meandrina meandrites from survey transects, leading to a significant shift in community composition. Cover of several species declined between October 2019 and May 2022, but only Siderastrea siderea experienced sustained declines into December of 2022. Overall cover of scleractinian corals decreased from 13.2 to 7.9% during the monitoring period. The ecological impacts of SCTLD in the area surrounding Carrie Bow Cay are consistent with reports from elsewhere in the Caribbean, underscoring the magnitude of colony density and coral cover loss caused by SCTLD across the region.

ecology↗

bioRxiv2026

Baseline microbiomes of the pillar coral Dendrogyra cylindrus reveal novel taxa and regional differences

The pillar coral Dendrogyra cylindrus is a rare but iconic member of Caribbean reefs that has suffered range-wide losses. D. cylindrus is highly susceptible to stony coral tissue loss disease (SCTLD), and the outbreak has contributed to the functional extinction of Floridas population of pillar corals. The coral microbiome can impact the health and disease resistance of coral colonies, yet little is known about what constitutes the core microbiome of D. cylindrus. This information is crucial for comparisons of healthy and diseased tissue in pathogen identification studies and can be applied to restoration efforts as a coral health metric. Therefore, we characterized the microbiomes of D. cylindrus colonies ahead of the SCTLD disease front in Belize and Curacao. The most prevalent members of the D. cylindrus microbial community were bacteria for which taxonomy could not be assigned confidently beyond the level of domain as well as the putatively endosymbiotic genera Endozoicomonas, Ca. Amoebophilus, and Spiroplasma. The coral reefs of Belize and Curacao represent distinct Caribbean marine ecoregions, and we documented regional differences in strains among predominant bacterial taxa. The understudied microbiome of D. cylindrus harbors unique bacterial lineages that are in danger of extinction along with its critically endangered coral host, and these bacterial lineages may be important bioindicators during restoration efforts. IMPORTANCETropical corals face global extinction if average temperatures rise by 2{degrees}C (3.6{degrees}F), which may occur as soon as 2050. Included in the loss of charismatic macrofauna like the majestic pillar coral is the loss of the biological and genetic diversity of its symbionts. Here we examined the bacterial and archaeal communities associated with Caribbean pillar corals and found that the microbiome was dominated by taxonomically unclassified and putatively endosymbiotic taxa. Endosymbiotic bacteria, which live inside the coral tissue, are likely to have evolved unique adaptations to become symbionts and may be important to the health and success of pillar corals in ecosystem restoration efforts.

microbiology↗

bioRxiv2024

Temperature drives seagrass recovery across the Western North Atlantic

Climate-driven shifts in herbivores, temperature and nutrient runoff threaten coastal ecosystem resilience. However, our understanding of ecological resilience, particularly for foundation species, remains limited due to a rarity of field experiments that are conducted across appropriate spatial and temporal scales and that investigate multiple stressors. This study aimed to evaluate the resilience of a widespread tropical marine plant (turtlegrass) to disturbances across its geographic range and how this is impacted by environmental gradients in (a)biotic factors. We assessed the resilience (i.e. recovery) of turtlegrass to a simulated disturbance (complete above- and belowground biomass removal) over a year. Contrary to temperate studies, higher temperature generally enhanced seagrass recovery. While nutrients and light availability had minimal impact, combined high levels of nutrients and herbivore grazing (meso and megaherbivore) reduced aboveground recovery. Our results suggest that the resilience of some tropical species, especially in cooler subtropical waters, may initially increase with warming.

ecology↗

bioRxiv2024

Infection-on-Chip: an in vitro human vessel to study Neisseria meningitidis colonization and vascular damages

Systemic infections leading to sepsis are life-threatening conditions that remain difficult to treat, and the limitations of current experimental models hamper the development of innovative therapies. Animal models are constrained by species-specific differences, while 2D cell culture systems fail to capture the complex pathophysiology of infection. To overcome these limitations, we developed a laser photoablation-generated, three-dimensional microfluidic model of meningococcal vascular colonization, a human-specific bacterium that causes sepsis and meningitis. Laser photoablation-generated hydrogel engineering allows the reproduction of vascular networks that are major infection target sites, and this model provides the relevant microenvironment reproducing the physiological endothelial integrity and permeability in vitro. By comparing with a human-skin xenograft mouse model, we show that the model system not only replicates in vivo key features of the infection, but also enables quantitative assessment with a higher spatiotemporal resolution of bacterial microcolony growth, endothelial cytoskeleton rearrangement, vascular E-selectin expression, and neutrophil response upon infection. Our device thus provides a robust solution bridging the gap between animal and 2D cellular models, paving the way for a better understanding of disease progression and developing innovative therapeutics.

synthetic biology↗

bioRxiv2023

Linking bacterial tetrabromopyrrole biosynthesis to coral metamorphosis

An important factor dictating coral fitness is the quality of bacteria associated with corals and coral reefs. One way that bacteria benefit corals is by stimulating the larval to juvenile life cycle transition of settlement and metamorphosis. Tetrabromopyrrole (TBP) is a small molecule produced by bacteria that stimulates metamorphosis in a range of coral species. A standing debate remains, however, about whether TBP biosynthesis from live Pseudoalteromonas bacteria is the primary stimulant of coral metamorphosis. In this study, we create a Pseudoalteromonas sp. PS5 mutant lacking the TBP brominase gene, bmp2. Using this mutant, we confirm that the bmp2 gene is critical for TBP biosynthesis in Pseudoalteromonas sp. PS5. Mutation of this gene ablates the bacteriums ability in live cultures to stimulate the metamorphosis of the stony coral Porites astreoides. We further demonstrate that expression of TBP biosynthesis genes is strongest in stationary and biofilm modes of growth, where Pseudoalteromonas sp. PS5 might exist within surface-attached biofilms on the sea floor. Finally, we create a modular transposon plasmid for genomic integration and fluorescent labeling of Pseudoalteromonas sp. PS5 cells. Our results functionally link a TBP biosynthesis gene from live bacteria to a morphogenic effect in corals. The genetic techniques established here provide new tools to explore coral-bacteria interactions and could help to inform future decisions about utilizing marine bacteria or their products for restoring degraded coral reefs.

microbiology↗

bioRxiv2023

Characterizing transcriptomic responses to sediment stress across location and morphology in reef-building corals

Anthropogenic activities increase sediment suspended in the water column and deposition on reefs can be largely dependent on colony morphology. Massive and plating corals have a high capacity to trap sediments, and active removal mechanisms can be energetically costly. Branching corals trap less sediment, but are more susceptible to light limitation caused by suspended sediment. Despite deleterious effects of sediments on corals, few studies have examined the molecular response of corals with different morphological characteristics to sediment stress. To address this knowledge gap, this study assessed the transcriptomic responses of branching and massive corals in Florida and Hawai{square}i to varying levels of sediment exposure. Gene expression analysis revealed a molecular responsiveness to sediments across species and sites. Differentially Gene Expression (DEG) followed by Gene Ontology (GO) enrichment analysis identified that branching corals had the largest transcriptomic response to sediments, in developmental processes and metabolism, while significantly enriched GO terms were highly variable between massive corals, despite similar morphologies. Comparison of DEGs within orthogroups revealed that while all corals had DEGs in response to sediment, there was not a concerted gene set response by morphology or location. These findings illuminate the species specificity and genetic basis underlying coral susceptibility to sediments.

bioinformatics↗

bioRxiv2022

Neutrophils degranulate GAG-containing proteoglycofili, which block Shigella growth and degrade virulence factors

Summary paragraphNeutrophil degranulation plays a central role in their ability to kill pathogens but also to stimulate other immune cells1-3. Here we show that neutrophil degranulation, induced in hypoxia or upon Shigella infection in vitro and in vivo, leads to the release of polymers called neutrophil Proteoglycofili (PGF). PGF are mainly composed of granular proteins (myeloperoxidase, elastase, lactoferrin, cathelicidin, albumin) pre-stored in various types of granules, and chondroitin sulfate. PGF individual fibers have a diameter of 43.9 {+/-} 20.3 nm and. They secreted by viable neutrophils and do not contain DNA, as opposed to NETs which contains also granular proteins, chondroitin sulfate in addition to chromatin, released upon neutrophil disintegration and cell death. We demonstrated that PGF block the growth of Shigella and other bacteria and degrade Shigella virulence factors. The degradation of the chondroitin sulfate polymers with testes hyaluronidases destabilizes PGF ultrastructure and abolishes its antimicrobial activity. Our results provide novel insights in the neutrophil degranulation process and open new doors for the investigation of PGF contribution to cytokines concentration gradient formation and adaptive immune cells activation. Further investigations are required to better appreciate the importance of this "sterile blaster" in infectious or inflammatory diseases.

immunology↗