Gene expression in hypoxia-tolerant Drosophila melanogaster

Hypoxia plays a key pathogenic role in the outcome of many pathologic conditions. To elucidate how organisms successfully adapt to hypoxia, a population of Drosophila melanogaster was generated, through an iterative selection process, that is able to complete its lifecycle at 4% O2, a level lethal to the starting parental population. Transcriptomic analysis of flies adapted for >200 generations was performed to identify pathways and processes that contribute to the adapted phenotype, comparing gene expression of three developmental stages with generation-matched control flies. A third group was included, hypoxia-adapted flies reverted to 21% O2 for five generations, to address the relative contributions of genetics and hypoxic environment to the gene expression differences. We identified the largest number of expression differences in 0.5-3 hr post-eclosion adult flies that were hypoxia-adapted and maintained in 4% O2, and found evidence that changes in Wnt signaling contribute to hypoxia tolerance in flies. A population of flies able to complete their life cycle at 4% O2 was selected from a starting population of 27 isogenic D. melanogaster lines exposed to increasingly lower O2 levels over many generations. Transcriptomic analysis of adapted flies maintained at 4% O2 or reverted to room air for five generations, and of generation matched naive controls, was performed to better understand changes in gene expression in adapted flies and to investigate the relative contributions of genetics versus environment to these differences.