Role of social interactions in modulating circadian clocks of camponotus ants and drosophila melanogaster

Abstract

Circadian clocks are endogenous time keeping systems whose period is largely protected against changes in ambient conditions. Nevertheless, they can be fine-tuned by environmental time cues (Zeitgebers) in a way that the period becomes indistinguishably close to 24 hr, and acquires a unique and reproducible phase-relationship with the environmental cycles (Daan and Aschoff, 2001). These clocks drive a variety of behavioural and physiological rhythms in a wide range of organisms from bacteria to humans, and help organisms in anticipating daily and seasonal events in their environment (Dunlap et al., 2004; Allada and Chung et al., 2010). Circadian clocks are believed to be of great adaptive value to organisms living under periodic as well as constant conditions as they enhance their fitness by coordinating various behavioural and physiological processes to external environmental and internal metabolic cycles (Ouyang et al., 1998; Sharma, 2003a). The earliest step to characterize the rhythm generating/regulating mechanisms at the gene level was taken in 1971 by Konopka and Benzer, when they found that three alleles of a newly discovered gene period (per) - per L (long period of ~ 29hr), per S (short period of ~ 19hr) and per 0 (arrhythmic phenotype) have impact on the activity/rest and adult emergence rhythms (Konopka and Benzer, 1971). Following the identification of per gene, other clock genes such as timeless (tim), clock (clk), cycle (cyc), and Cryptochrome (cry) in Drosophila; frequency (frq) and white collar (wc-1,wc-2) in Neurospora; and KaiA, KaiBC in cyanobacteria; Clock (Clk), Period1-3 (Per1-3), Bmal1, and Cry1-2 in mammals were identified (Shearman 2000; 9 Johnson 2001; Cheng et al 2001; Allada and Chung, 2010; Dunlap et al., 2004).