Project name: Drosophila melanogaster

Description: Background. The transcriptional circuits of circadian clocks control physiologicaland behavioral rhythms. Light may affect such overt rhythms in two ways: (1) byentraining the clock circuits and (2) via clock-independent molecular pathways. Inthis study we examine the relationship between autonomous transcriptoscillations and light-driven transcript responsesMethodology/Principal Findings. Transcript profiles of wild-type and arrhythmicmutant Drosophila were recorded both in the presence of an environmentalphotocycle and in constant darkness. Systematic autonomous oscillations in the12-48 hr period range were detectable only in wild-type flies and occurredpreferentially at the circadian period length. However, an extensive program oflight-driven expression was confirmed in arrhythmic mutant flies. Many lightresponsivetranscripts are preferentially expressed in the adult compound eyeand the phospholipase C component of phototransduction, NO RECEPTORPOTENTIAL (NORPA), is required for their light-dependent regulation.Conclusions/Significance. Although there is growing evidence for the existenceof multiple molecular clock circuits in plants and fungi, Drosophila appears topossess only one such system. The sustained photic expression responsesidentified here are partially coupled to the circadian clock and may reflect amechanism for flies to modulate functions such as visual sensitivity and synaptictransmission in response to seasonal changes in photoperiod.Keywords: Time courseOverall design: y w; tim01 flies that had been kept in a 12-hr light/ 12-hr dark cycle for three days were harvested every four hours during an additional light/dark day (ZT) and a subsequent day in constant darkness (CT). Relative to Zeitgeber time 0 (ZT0) as the time of lights onduring the LD cycle and Circadian time 0 (CT0) as the time corresponding tosubjective lights-on during freerun in DD, time courses were collected in a ZT2-ZT6-ZT10-ZT14-ZT18-ZT22-CT2-CT6-CT10-CT14-CT18-CT22 schedule. Headswere isolated by breaking up frozen flies and passing them through a set ofsieves. RNA was prepared using guanidine-thiocyanate extraction followed bypurification over a CsCl gradient. Additional purification of the RNA samples wasachieved by applying them to Rneasy columns (Qiagen). Biotin-labeled cRNAprobe was generated from 25 μg of purified RNA and hybridized as describedpreviously (Wijnen H, Naef F, and Young MW, Methods Enzymol. 2005; 393: 341-365).For more information see also http://biorhythm.rockefeller.edu

Data type: Transcriptome or Gene expression

Sample scope: Multiisolate

Relevance: ModelOrganism

Release date: 2006-02-03

Last updated: 2005-12-14