Meeting Abstract
Northern elephant seals (Mirounga angustirostris) are subjected to prolonged periods of fasting of up to three months depending on age and gender. In pups, this fast occurs during the postweaning phase, an 8 to 12-week period during which they rely solely on the energy reserves gained during nursing for their caloric requirements and water supply. The postweaning fast is the first of many, and it helps the pup to develop into a diving marine mammal that is capable of foraging at sea. The purpose of this study was to understand the fasting and diving-induced developmental changes of pups during this critical transition from a terrestrial to aquatic lifestyle. To investigate this, we collected skeletal muscle and adipose tissue from pups early and late in the developmental fast. We analyzed the samples with mass-spectrometry-based proteomics using 2D gel electrophoresis. We found significant shifts in metabolic proteins that suggest a decrease in amino acid metabolism and urine production during the postweaning fast, and an increase in alternative metabolic pathways (such as the pentose phosphate pathway) that support cell proliferation. We also found increases in cytoskeletal, skeletal muscle, and oxygen-binding proteins that aid in the development of the diving ability in pups. There were also shifts in the abundance of acute phase proteins that support an increased immune response, possibly due to a higher risk of inflammation from microbial infection. Lastly, there was a shift in antioxidant isoforms that control the production of reactive oxygen species. These results provide key physiological information regarding the developmental pathways of pups throughout ontogeny.
