title: Significance of activity peaks in fruit flies, Drosophila melanogaster, under seminatural conditions.
abstract: Studies on circadian entrainment have traditionally been performed under controlled laboratory conditions. Although these studies have served the purpose of providing a broad framework for our understanding of regulation of rhythmic behaviors under cyclic conditions, they do not reveal how organisms keep time in nature. Although a few recent studies have attempted to address this, it is not yet clear which environmental factors regulate rhythmic behaviors in nature and how. Here, we report the results of our studies aimed at examining (i) whether and how changes in natural light affect activity/rest rhythm and (ii) what the functional significance of this rhythmic behavior might be. We found that wild-type strains of fruit flies, Drosophila melanogaster, display morning (M), afternoon (A), and evening (E) peaks of activity under seminatural conditions (SN), whereas under constant darkness in otherwise SN, they exhibited M and E peaks, and under constant light in SN, only the E peak occurred. Unlike the A peak, which requires exposure to bright light in the afternoon, light information is dispensable for the M and E peaks. Visual examination of behaviors suggests that the M peak is associated with courtship-related locomotor activity and the A peak is due to an artifact of the experimental protocol and largely circadian clock independent.
authors.affiliation: Behavioural Neurogenetics Laboratory, Evolutionary and Organismal Biology Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560064, India.
authors.forename: Joydeep
authors.initials: J
authors.lastname: De
authors.forename: Vishwanath
authors.initials: V
authors.lastname: Varma
authors.forename: Soham
authors.initials: S
authors.lastname: Saha
authors.forename: Vasu
authors.initials: V
authors.lastname: Sheeba
authors.forename: Vijay Kumar
authors.initials: VK
authors.lastname: Sharma
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001522:Behavior, Animal / Q000502:physiology*; D002940:Circadian Rhythm / Q000502:physiology*; D004331:Drosophila melanogaster / Q000502:physiology*; D009043:Motor Activity / Q000502:physiology*; D019370:Observation; D017440:Photoperiod; D012726:Sexual Behavior, Animal / Q000502:physiology; D013997:Time Factors
keywords: afternoon peak; chronoethogram; circadian rhythms; courtship; period mutants