Blubber transcriptome and proteome responses to repeated adrenocorticotropic hormone administration in a marine mammal
Chronic physiological stress impacts animal fitness by catabolizing metabolic stores and suppressing reproduction and immunity. This can be especially deleterious for capital breeding carnivores, such as marine mammals, which rely on lipid stores accrued during intensive foraging to sustain prolonge...
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Scholarly Commons
2019
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| Online Access: | https://scholarlycommons.pacific.edu/uop_etds/3598 https://scholarlycommons.pacific.edu/context/uop_etds/article/4579/viewcontent/Deyarmin_pacific_0173N_10494.pdf |
| Summary: | Chronic physiological stress impacts animal fitness by catabolizing metabolic stores and suppressing reproduction and immunity. This can be especially deleterious for capital breeding carnivores, such as marine mammals, which rely on lipid stores accrued during intensive foraging to sustain prolonged periods of fasting associated with reproduction. Therefore, chronic stress may cause a decrease in fitness in these animals, leading to population declines and potentially detrimental shifts in food web dynamics as a result. However, the impacts and indicators of chronic stress in animals are currently poorly understood. To identify downstream mediators of repeated stress responses in marine mammals, adrenocorticotropic hormone (ACTH) was administered once daily for four days to free-ranging juvenile northern elephant seals (Mirounga angustirostris) to stimulate endogenous corticosteroid release. I then compared blubber tissue transcriptome responses to the first and fourth ACTH administrations to determine the effects of acute and chronic endocrine stress, respectively. Gene expression profiles showed differences in responses to single and repeated ACTH administration, despite similarities in circulating cortisol profiles. We identified 61 and 12 differentially expressed genes (DEGs) in response to the first ACTH and fourth administrations, respectively, 24 DEGs between the first and fourth pre-ACTH samples, and 12 DEGs between ACTH response samples from the first and fourth days. Annotated DEGs were associated with functions in redox and lipid homeostasis, suggesting potential negative impacts of repeated stress on marine mammals. In addition, protein expression profiles were discrete between single and repeated ACTH administrations, and identified changes in expression of extracellular proteins that were not detected at the transcriptome level. We identified 8 and 7 differentially expressed proteins (DEPs) in response to the first and fourth ACTH administrations, respectively, including 5 DEPs in the overall ACTH ... |
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