Meeting Abstract
Few vertebrates survive weeks to months without oxygen. The most anoxia-tolerant vertebrate known is the annual killifish Austrofundulus limnaeus, whose embryos survive over 100 days of anoxia. On-going studies examine mechanisms supporting this tolerance, but comparative studies with other anoxia-tolerant vertebrates are lacking. This study examines the role of small RNAs in the evolution of vertebrate anoxia tolerance. Small RNAs are specific, rapid, and reversible regulators of gene expression, making them interesting candidates for coordinating the entry into and exit from anoxia. Analysis of small RNA expression in A. limnaeus embryos revealed specific small RNAs, including several novel sequences, that appear to play important roles in anoxia tolerance. Here we conduct a comparative study on small RNA expression in the most anoxia-tolerant species of major vertebrate lineages, to understand the evolution of extreme anoxia tolerance. The epaulette shark, crucian carp, western painted turtle, and leopard frog were exposed to anoxia and recovery at ecologically relevant temperatures and times, and small RNAs were sequenced from the brain (the most anoxia sensitive organ) prior to, during, and following exposure to anoxia. Small RNA expression patterns differed remarkably between species, indicating that small RNAs have evolved distinctly in each species to support anoxia tolerance. Interestingly, many of the novel sequences identified in A. limnaeus do not appear to play a role in the anoxia tolerance of the other species, indicating that A. limnaeus possess unique biology, worthy of further investigation.
