Meeting Abstract
Weddell seals are a deep-diving Antarctic species that have been the subject of many seminal studies on diving physiology and behavior. Isolated dive-hole experimental paradigms allowed physiological telemetry and biochemical samples to be collected from unrestrained and freely foraging seals. From these studies, we now recognize the Weddell seal as an elite diver, capable of surviving profound hypoxemia upon submergence, and exhibiting extreme cardiovascular adjustment to distribute limited oxygen stores to key tissues. The mechanisms that define cardiovascular control and provide cell-level protection against hypoxia and subsequent reoxygenation represent the next level in our understanding of the strategies of this extreme breath-hold diver. Neither genetic nor pharmacological manipulations are possible in Antarctic marine mammals, however the availability of a sequenced genome as well as emerging primary cell culture resources provide new avenues to apply modern molecular tools to these questions. Targeted analyses have revealed limited but significant differences in protein coding sequences that can be linked to diving traits such as oxygen storage and vasoregulation. On the other hand, comparative genomic analyses have identified gene regulation as the major signal of evolutionary innovation in the Weddell seal. In particular, differential expression of microRNAs as well as HIF-1a-regulating transcription factors may be important aspects of cardiovascular physiology that enable Weddell seals to dive long and deep.
