Towards a molecular understanding of allostasis in free‐ranging marine mammals (703.6)

Abstract

Chronic stress negatively affects reproduction and survival of pelagic predators, threatening ecosystem stability. However, our understanding of the stress response in marine mammals is limited and largely based on terrestrial model systems that do not reflect pelagic life history adaptations. We are examining the molecular signature of allostasis in northern elephant seals to develop species‐specific stress diagnostic tools and resolve interactions between the hypothalamic‐pituitary‐adrenal (HPA) axis and other physiological pathways. We conducted stress tests in juvenile elephant seals by intramuscular adrenocorticotropic hormone (ACTH) injection to analyze the magnitude and duration of the HPA axis response. To investigate global gene expression changes in response to a stress challenge, we sequenced RNA isolated from muscle tissue of animals before and after ACTH injection. De novo transcriptome assembly and analysis was performed using the Trinity platform and yielded a reference transcriptome for the northern elephant seal study system. We have identified a number of genes and pathways altered during the stress response in a free‐ranging marine mammal, including several candidate molecular markers of stress. Our data indicate that the magnitude of the stress response to ACTH stimulation provides key information about an animal’s physiological state.Grant Funding Source: Office of Naval Research