Precision and temperature entrainment mechanism of the circadian clock

Abstract : Most of the organisms show daily rhythms in various physiological, behavioral functions regulated by an endogenous circadian clock. Although there is evidence for the adaptive advantage of some rhythmic processes being more precise than others, how circadian clocks with high precision have evolved has never been subjected to systematic empirical investigation. I will discuss the experiments with Drosophila melanogaster populations to elucidate the adaptive evolution of precision and stability of circadian clocks under imposed artificial selection for timing of clock controlled behavior. Biological clock runs with an endogenous period of about 24 hour under constant conditions, but runs exactly 24 hour and maintain a stable phase-relationship with daily environmental cycles (zeitgebers) such as light, temperature, humidity, and social interaction cycles through the process known as entrainment. Although temperature cycle is an important time cue for entrainment, little is known about the mechanism through which temperature resets the clock. In addition to the studies on Drosophila, I will discuss about the molecular temperature entrainment mechanism of the circadian clock in cricket, Gryllus bimaculatus. The outcome of this study shows the specific role of key clock genes in temperature entrainment and provide evidence on how the biological clock system synchronizes with the environmental temperature time cue.