Project description:Some rookeries of the western distinct population segment (WDPS) of Steller sea lions (Eumetopias jubatus) in the Aleutian Islands (Alaska, USA) have experienced continued declines since the initial collapse of the population in the 1970-1980s. Several theories have been put forward to explain the decline and lack of subsequent recovery including predation, nutritional stress, contaminants, and infectious disease agents, but thus far a primary cause has not been identified. Examining gene expression profiles of organisms has been promoted as a way to assess several health indicators related to toxicoses, infection, and nutritional stress using recent advances in metagenetics (next-generation sequencing) analyses. Next-generation sequencing may provide a more refined and adaptable method of investigating sea lion health under difficult research field collections. Here we suggest that the application of next-generation sequencing tools has the potential to evaluate the transcriptomic (gene expression) profile of animals from declining rookeries. We show that high quality RNA can be obtained from wildlife populations despite logistically challenging field conditions. We compared RNA expression in whole blood using whole transcriptome sequencing (RNA-Seq) among animals with relatively high concentrations of total mercury ([THg]) to animals with lower concentrations. There did not appear to be significant changes in gene expression in animals with high [THg] in whole blood, despite some animals having concentrations above thresholds of concern for model organisms. We did find evidence of a bias toward downregulation of some genes in animals with higher [THg].
Project description:In this study we assessed the utility of a microarray to identify changes in gene expression predictive of health status by interrogating blood samples from California sea lions in rehabilitation. 73 California sea lion blood samples. 28 Females and 45 males. Animals were divided into 4 groups based on preliminary diagnosis at the rehabilitation center: domoic acid toxicosis (n=33, DAT), Leptospirosis infection (n=24, Lepto), control (n=4, Healthy) and other diseases (n=12, Outgroup).
Project description:The neurotoxic amino acid, domoic acid, is naturally produced by marine phytoplankton and presents a significant health threat to marine mammal and human populations. Currently, diagnostic tools to assess exposure are not available, yet concerns regarding health impacts associated with low-level repetitive exposure are growing. Here we applied a laboratory zebrafish model to assess exposure to asymptomatic doses of domoic acid in a nine-month low-level repetitive exposure study. Blood analyses, whole brain gene expression, and functional lymphocyte proliferation assays analyzed at 11 time points revealed a quantifiable antibody response that was temporally correlated with upregulated immune response genes and significantly increased spontaneous lymphocyte proliferation. The antibody response was further validated in field exposed California sea lions and provides the first biomarker for chronic exposure assessment. Time series domoic acid exposure of zebrafish.
