Characterizing Genetic Mechanisms Involved in Measuring Day-length in Drosophila melanogaster

In the current study, we performed a genome-wide association study (GWAS) on photoperiodism using the Drosophila Genetic Reference Panel. The GWAS identified 32 candidate genes responsible for photoperiodic regulations. The knockout mutants of the top four candidate genes (Protein Kinase C delta (Pkcdelta), Glucuronyltransferase-P (GlcAT-P), Brain-specific homeobox (Bsh), and Diuretic hormone 31 Receptor (Dh31-R1)) were analyzed for their photoperiod and circadian period phenotypes. PKCdelta and GlcAT-P mutants show a significantly different photoperiod response compared to that of the wild type strain, and also had an altered circadian period phenotype. Further molecular characterization revealed that the mutant two independent mutant alleles of PKCdelta with a defective catalytic domain had distinct photoperiod responses. Taken these data together, we concluded that there is overlap between the circadian clock and photoperiodic regulations in Drosophila, and PKCdelta is a component that is involved in both circadian and photoperiodic regulations. By identifying novel molecular components of photoperiod, the current study provides new insights into the genetic mechanisms of determining the seasonal changes.