Characterization of the abnormal circadian phenotype in a Drosophila DGRP line

Circadian clocks are common to most living organisms and control a wide range of physiological and behavioral functions to allow adaptation to environmental day-night conditions. Screenings to study the genetic basis of the natural polymorphism of sleep-wake rhythms highlighted one line from the DGRP project with a long circadian period. The Rouyer lab found that the behavioral phenotype is a consequence of two mutations on the second and third chromosomes of this DGRP* line. One mutation is in the timeless (tim) gene and a mutation on the third chromosome appears to be in the Dop1R2 dopamine receptor gene. The goal of this project was to confirm and characterize the mutation on the third chromosome through behavioral and bioinformatic analyses. We were able to confirm Dop1R2 as the mutated gene on the third chromosome and showed that the altered expression of the receptor in PDF-expressing clock neurons only in the presence of the tim mutation results in a phenotype similar to DGRP*. Moreover, it appears that changes in dopamine levels similarly affect the circadian behavior. Further work is needed to better identify the involved neurons and to analyze the pathway that links the dopamine receptor to tim.