Biology subjects

Gerard, T.

Publications and source records attributed to Gerard, T..

3 recordsLinked to original sources

bioRxiv2025

Prostate-specific EV capture with sufficient RNA yield to enable transcriptomic profiling

Prostate-specific antigen (PSA) screening has reduced prostate cancer (PCa) mortality but suffers from limited specificity, contributing to unnecessary biopsies and overdiagnosis of indolent disease. There is a critical need for biofluid-based biomarkers that improve the precision of PCa detection. Extracellular vesicles (EVs) offer a promising platform for noninvasive diagnostics, as they carry molecular cargo reflective of their tissue of origin. The ExoDx Prostate IntelliScore (EPI) test, a urine-based EV assay, is currently the only commercial EV diagnostic for clinically significant (cs)PCa, but its performance may be constrained by contamination from renal and bladder-derived EVs. To address this, we developed Exosome Diagnostics Depletion and Enrichment (EDDE), a novel immunocapture-based method for isolating prostate-derived EVs with high specificity. By targeting Prostate Specific Membrane Antigen (PSMA), we optimized EDDE to selectively enrich prostate EVs from post-DRE urine and recover sufficient RNA for transcriptomic analysis. Throughout development, we implemented a quantitative framework to track EV stoichiometry and assess depletion efficiency and yield, enabling rigorous optimization of the workflow. Our findings demonstrate that PSMA EDDE enriches prostate-specific EVs and yields RNA quantities compatible with sequencing. This platform enhances the specificity of EV-based biomarker discovery and holds promise for determining if tissue-specific EV biomarkers contribute advantages over bulk EVs.

cancer biology↗

bioRxiv2020

Trade-offs between risks of predation and starvation in larvae make the shelf break an optimal spawning location for Atlantic Bluefin tuna

Atlantic Bluefin tuna (ABT) (Thunnus thynnus) travel long distances to spawn in oligotrophic regions of the Gulf of Mexico. To estimate regional larval ABT mortality, we developed a spatially-explicit, Lagrangian, individual-based model that simulates dispersal, growth, and mortality within realistic predator and prey fields during the spawning periods from 1993-2012. Modelled larval ABT experience high mortality in the first week of feeding with an average mortality rate of 0.53 {+/-} 0.26 d-1 prior to postflexion. Survival ranged from 0.12%-0.32% suggesting that recruitment may vary by a factor of 2.7 due to early life stage mortality alone. Starvation is the dominant source of mortality driven by the early critical period; however, survival is ultimately limited by predation on older individuals. As a result, first-feeding larvae survive better in the more food-rich areas on the shelf, while larger larvae survive better in the open ocean with fewer predators, making the shelf break an optimal spawning area. Our findings support the hypothesis that ABT spawn in oligotrophic regions to minimize predation on their larvae. Ocean modeling tools presented in this study may help facilitate an ecosystem-based management approach to improve future stock assessment models by better resolving the stock-recruitment relationship.

ecology↗

bioRxiv2020

Plankton food webs of the Gulf of Mexico spawning grounds of Atlantic Bluefin tuna

We used linear inverse ecosystem modeling techniques to assimilate data from extensive Lagrangian field experiments into a mass-balance constrained food web for the Gulf of Mexico open-ocean ecosystem. This region is highly oligotrophic, yet Atlantic Bluefin Tuna (ABT) travel long distances from feeding grounds in the North Atlantic to spawn there. Our results show that the food web is dominated by the microbial loop (>80% of net primary productivity is respired by heterotrophic bacteria and protists that feed on them). In contrast, herbivorous food web pathways from phytoplankton to metazoan zooplankton process <4% of net primary production in the mixed layer. Nevertheless, ABT larvae feed preferentially on calanoid copepods and other suspension-feeding zooplankton that in turn derive much of their nutrition from diatoms and mixotrophic flagellates. This allows ABT larvae to maintain a comparatively low trophic level ([~]4.0 for pre-flexion larvae; [~]4.2 for post-flexion larvae) that increases trophic transfer from phytoplankton to larval fish.

ecology↗