Kaitlin Allen is a graduate student at the University of California, Berkeley where she studies the physiology of elephant seals in the laboratory of Dr. José Pablo Vázquez-Medina. She received the 2024 Dr. Dolittle Travel Award from the Comparative and Evolutionary Physiology section of the American Physiological Society to attend the 2024 American Physiology Summit in Long Beach, CA (April 4-7).
Kaitlin prepared this award-winning guest blog entry to describe her research:
If you’ve ever had the opportunity to see an elephant seal lounging on the beach, “athletic” is unlikely to have been the first word that came to mind. These animals can weigh thousands of pounds and sometimes look like gigantic-but-slightly-deflated beach balls when hauled out on shore. However, elephant seals are some of the most elite divers in the mammalian world, spending up to 90% of their at-sea time submerged (Robinson et al., 2012). When you consider building athletic capacity as a human, you focus on two main things: training and nutrition. In building their diving capacity as pups, however, elephant seals don’t utilize either of these strategies. Moms nurse their pups on land for about a month, during which time the pup gains about 250 pounds on its birth weight, generally weaning at nearly 300 pounds. However, the pup is not “training” during this time: they stay on land, out of the water, for about 10 weeks, and they don’t know how to swim – which means they don’t eat! Paradoxically, this land-based fast is critical to the development of pups’ athletic diving capacity.
The overall framework of this fasting period has been well characterized over the years, including an understanding that fasting enhances the capacity for apnea-related metabolic suppression in elephant seal pups. However, these are large and often difficult-to-handle wild animals, which places constraints on the types of metabolic analyses that can be done. We developed an in vitro cell culture system from muscle biopsies to study the impact of fasting on muscle metabolism in elephant seal pups. The cells are developed from animals “early” and “late” in the fasting period, and we compared the capacity for each to produce ATP as well as the metabolic pathways responsible for ATP production. We found that cells from animals late in the fasting period produced ATP more rapidly than those from animals earlier in the fast. This difference was driven by an increased reliance on glycolysis, which is an oxygen-independent metabolic pathway. Prior work in hibernating grizzly bear cells has shown that serum (blood) from hibernating and active states can differentially influence cell metabolism (Hapner Hogan et al., 2022), and we were excited to find that in seals the cells themselves retain differential metabolic profiles when serum status is controlled.
Overall, it’s impressive that elephant seal pups can develop such a strong diving capacity – an athletic feat – without actually diving, and with what any human endurance athlete would consider an incredibly poor nutrition strategy!
References
Robinson, P. W. et al. Foraging Behavior and Success of a Mesopelagic Predator in the Northeast Pacific Ocean: Insights from a Data-Rich Species, the Northern Elephant Seal. PLoS ONE 7, e36728 (2012).
Ponganis, P. Diving Physiology of Marine Mammals and Seabirds. (Cambridge University Press, 2015). doi:10.1017/CBO9781139045490.
Hapner Hogan, H. R., Hutzenbiler, B. D. E., Robbins, C. T. & Jansen, H. T. Changing lanes: seasonal differences in cellular metabolism of adipocytes in grizzly bears (Ursus arctos horribilis). J Comp Physiol B (2022) doi:10.1007/s00360-021-01428-z.
Categories: Diet and Exercise, Extreme Animals, Nature's Solutions, Ocean Life, Physiology on the Road
Tags: American Physiological Society, American Physiology Summit, animals, Athletic, diving, elephant seal, fasting, fitness, health, travel, weight loss
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