title: Interaction of light regimes and circadian clocks modulate timing of pre-adult developmental events in Drosophila.
abstract: BACKGROUND
  Circadian clocks have been postulated to regulate development time in several species of insects including fruit flies Drosophila melanogaster. Previously we have reported that selection for faster pre-adult development reduces development time (by ~19 h or ~11%) and clock period (by ~0.5 h), suggesting a role of circadian clocks in the regulation of development time in D. melanogaster. We reasoned that these faster developing flies could serve as a model to study stage-specific interaction of circadian clocks and developmental events with the environmental light/dark (LD) conditions. We assayed the duration of three pre-adult stages in the faster developing (FD) and control (BD) populations under a variety of light regimes that are known to modulate circadian clocks and pre-adult development time of Drosophila to examine the role of circadian clocks in the timing of pre-adult developmental stages.
  
  
  RESULTS
  We find that the duration of pre-adult stages was shorter under constant light (LL) and short period light (L)/dark (D) cycles (L:D = 10:10 h; T20) compared to the standard 24 h day (L:D = 12:12 h; T24), long LD cycles (L:D = 14:14 h; T28) and constant darkness (DD). The difference in the duration of pre-adult stages between the FD and BD populations was significantly smaller under the three LD cycles and LL compared to DD, possibly due to the fact that clocks of both FD and BD flies are driven at the same pace in the three LD regimes owing to circadian entrainment, or are rendered dysfunctional under LL.
  
  
  CONCLUSIONS
  These results suggest that interaction between light regimes and circadian clocks regulate the duration of pre-adult developmental stages in fruit flies D. melanogaster.
authors.forename: Pankaj
authors.initials: P
authors.lastname: Yadav
authors.forename: Madhumohan
authors.initials: M
authors.lastname: Thandapani
authors.affiliation: Chronobiology Laboratory, Evolutionary and Organismal Biology Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, P, O, Jakkur, Bangalore, Karnataka 560064, India. vsharma@jncasr.ac.in.
authors.forename: Vijay Kumar
authors.initials: VK
authors.lastname: Sharma
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D057906:Circadian Clocks / Q000502:physiology*; D003624:Darkness; D004331:Drosophila melanogaster / Q000254:growth & development / Q000528:radiation effects*; D007814:Larva / Q000254:growth & development / Q000528:radiation effects; D008027:Light; D010063:Ovum / Q000254:growth & development / Q000528:radiation effects; D017440:Photoperiod; D010858:Pigmentation / Q000502:physiology / Q000528:radiation effects; D013997:Time Factors; D014921:Wings, Animal / Q000254:growth & development / Q000502:physiology / Q000528:radiation effects