Meeting Abstract
Many insect life stages have the potential to be exposed to hypoxia or even anoxia. Insects generally are much better at surviving anoxia than vertebrates, at least partly because the tracheal system permits restoration of tissue oxygen by diffusion. Surprisingly, we still lack a fundamental understanding of how anoxia kills and the mechanisms responsible for variation among species and developmental stages. Anoxia-tolerant vertebrates are able to maintain ATP levels during anoxia through a coordinated reduction in metabolism and/or elevated anaerobic metabolism. Here we tested whether maintenance of ATP can explain variation in anoxia-tolerance across Drosophila melanogaster strains and developmental stages. Adults survive anoxic durations much longer than larvae, anoxia tolerance decreases with adult age, and Drosophila Genetics Reference Panel lines exhibit 4-fold variation in anoxia tolerance. ATP declines to ~5% of resting within 30 min for adults and within 60 min for larvae, well before the time mortality begins to occur, suggesting loss of ATP does not immediately cause death. Similarly, preservation of ATP levels was not correlated with anoxia tolerance across development stages, age or genetic strain. As the primary hypothesis for variation in anoxia-tolerance in vertebrates was rejected, we conducted a GWAS to identify candidate genes responsible for variation in anoxia survival using the Drosophila Genetics Reference Panel. Survival of 1 hr of anoxia in 178 lines from the DGRP ranged from 25-95%; 23 genes were associated with variation in survival. Several of the identified genes have human orthologs that have been linked to oxygen-related pathologies in humans, as well as mechanisms involving immune function and general stress response. In insects, variation in anoxia tolerance seems to occur due to variation in the ability to cope with depleted ATP levels. Supported by NSF IOS 1256745.
