Genetics and Molecular Biology of Rhythms in Drosophila and Other Insects

摘要: Application of generic variants (Sections II-IV, VI, and IX) molecular manipulations rhythm-related genes V-X) have been used extensively to investigate features insect chronobiology that might not experimentally accessible otherwise. Most such tests mutants molecular-genetic xperiments performed in Drosophila melanogaster. Results from applying visual-system revealed environmental inputs the circadian clock adult flies are mediated by external photoreceptive structures (Section II) also direct light reception chat occurs certain brain neurons IX). The relevant light-absorbing molecuLes rhodopsins "blue-receptive" cryptochrome II Variations temperature another input IV), as has analyzed part use techniques transgenes involving factors functioning near heart VIII). At location within fly's chronobiological system, approximately a half-dozen-perhaps up many 10-clock encode functions act interact form pacemaker III V). This entity transcriptional control genes' expressions, which result production key proteins feed back negatively regulate their own mRNA production. interactions with others function activators implied feedback loop operates there daily variations abundances products put out about one-half core genes. Thus, normal expression these defines rhythms own, paralleling effects mutations at corresponding genetic loci III), disrupt or apparently eliminate functioning. fluctuations abundance gene controlled transciptionally posttranscriptionally. These mechanisms being ways increasingly complex occasionally obscure; all panels this picture comprehensive clear, including problems revolving round biological meaning given cycling Among complexities puzzles recently arisen, phenomena stand posttranslational modifications circadianly regulated regulating; biochemical events an ancillary component mechanism, identification Factors III) turned protein kinases whose substrates include other pacemaking polypeptides Outputs clocks long defined on formalistic some cases concrete criteria, related periodic eclosion locomotion III). Based reasoning if can cyclings products, they do same for along output pathways; thus clock-regulated identified virtue products' oscillations X). Those studied most intensively influenced circadian-pacemaker mutations. discovered criteria instances further mutant forms found affect overt whole-organismal rhythmicity IV Insect chronogenetics touches naturally occurring (in cases) otherwise informed investigators organism's rhythm system VII). Such animals least dozen species than D. melanogaster encountered (although usually looked systematically). "system" fruit fly better be graced plural appellation because is myriad temporally come under sway one kind putative variant IV). phenotypes, range well beyond bedrock locomotor rhythms, unfortunately lead creation laundry list underanalyzed occult may inherently real, whether meaningfully defective influence chronogenetic variant. However, seem lend themselves interrogation wide variety time-based attributes-those fall experimental confines conventionally appreciated II, III, X); consist 24-hr nondaily cycles kinds biological, physiological, parameters