Stress and metabolic regulation in Drosophila

Novel cytochrome P450, cyp6a17, is required for temperature preference behavior in Drosophila

Perception of temperature is an important brain function for organisms to survive. Evidence suggests that temperature preference behavior (TPB) in Drosophila melanogaster, one of poikilothermal animals, is regulated by cAMP-dependent protein kinase (PKA) signaling in mushroom bodies of the brain. However, downstream targets for the PKA signaling in this behavior have not been identified. From a genome-wide search for the genes regulated by PKA activity in the mushroom bodies, we identified the cyp6a17 Cytochrome P450 gene as a new target for PKA. Our detailed analysis of mutants by genetic, molecular and behavioral assays shows that cyp6a17 is essential for temperature preference behavior. cyp6a17 expression is enriched in the mushroom bodies of the adult brain. Tissue-specific knockdown and rescue experiments demonstrate that cyp6a17 is required in the mushroom bodies for normal temperature preference behavior. This is the first study, to our knowledge, to show PKA-dependent expression of a cytochrome P450 gene in the mushroom bodies and its role as a key factor for temperature preference behavior. Taken together, this study reveals a new PKA-Cytochrome P450 pathway that regulates the temperature preference behavior.

Stress tolerance and metabolic response to stress in Drosophila melanogaster

A potentially important physiological response to stress may be alteration in the gross regulation of energy metabolism. Different genotypes may respond differently to environmental stress, and the variation in these norms of reaction may be of key importance to the maintenance of genetic variation in metabolic traits. In the study reported here, a set of genetically defined lines of Drosophila melanogaster were exposed to four stresses (acetic acid, ethanol, starvation and thermal stress) in order to assess the magnitude of environmental effects and genotype x environment interactions. In addition to scoring metabolic traits, distributions of survival times under each stress were also quantified. Although both metabolic traits and survival times exhibited strong differences among genotypes, the correlations between enzyme traits and survival were generally weak. Many of the genetic correlations exhibit significant heterogeneity across environments. The results suggest that transient environmental stress may play an important role in the evolution of this highly intercorrelated set of metabolic traits.