Meeting Abstract
Northern elephant seals (Mirounga angustirostris) have several key physiological adaptations allowing them to develop from a terrestrial nursing pup to a juvenile able to dive and forage independently in the water. During the approximately 8-week time period between the weaning of the pup and their departure to sea, juvenile seals rely solely on the energy reserves they gained during nursing for all caloric and water demands. While adult elephant seals fast during molting, mating, and lactation, pups fast while undergoing a major transition from a terrestrial to an aquatic lifestyle. The purpose of this study was to understand the fasting-induced adaptive responses of pre- and post-weaning M. angustirostris pups using a proteomics approach. We collected tissue from skeletal muscle and the inner and outer adipose layers of both pre- and post- weaning pups (n = 20). After performing first and second dimension gel electrophoresis, we analyzed the samples using mass-spectrometry-based proteomics. In the post-weaning time-point, we identified significant decreases in proteins related to glycolytic metabolism, possibly indicating a shift from a carbohydrate to a lipid based metabolism in muscle. There were also increases in cytoskeletal proteins, as well as oxygen-binding proteins that aid in the development of diving ability in post-weaning pups. We found both significant increases and decreases in the abundance of proteins related to oxidative stress, highlighting how the unique stressors of each weaning phase effects the pup’s physiology differently. This study will provide important information about the adaptive capacity of marine mammals at a critical developmental stage.
