Molecular rhythms that regulate rhythm genes in Drosophila

Almost all living organisms display rhythms in their activities coinciding with the day-night cycles, Our current understanding of the molecular regul ation of circadian rhythmicity in Drosophila comes from studies integrating genetics and molecular biology, and Drosophila is perhaps one of the best understood models in the field of circadian rhythm research. Following the initial discovery of the per (period) gene some decades ago, several other genes, viz, timeless, dclock, cycle, and double-time, that function in the generation of circadian rhythms, have been identified during the past:three years: Molecular genetic studies have provided exciting insights into the regulation of the body clocks. Heterodimeric complexes of positive elements (dCLOCK and CYCLE) and their interactions with feedback loops and negative elements of per and fim genes and their products have been identified and these are-providing clues to the general layout of the molecular loops that generate circadian rhythms. The lark gene, which encodes an RNA-binding pr otein, might function as a regulatory element in the circadian: clock outpu t pathway controlling pupal eclosion rhythms.:However, a clear picture of t he output pathways or downstream processes through which the clock regulate s the circadian rhythmic events is yet to he understood.