title: Continuous activity and no cycling of clock genes in the Antarctic midge during the polar summer.
abstract: The extreme seasonal shifts of day length in polar regions, ranging from constant light in the summer to constant darkness in the winter, pose an intriguing environment for probing activity rhythms and the functioning of circadian clocks. Here, we monitor locomotor activity during the summer on the Antarctic Peninsula and under laboratory conditions, as well as the accompanying patterns of clock gene expression in the Antarctic midge, the only insect endemic to Antarctica. Larvae and adults are most active during the warmest portion of the day, but at a constant temperature they remain continuously active regardless of the photoregime, and activity also persists in constant darkness. The canonical clock genes period, timeless, Clock, and vrille are expressed in the head but we detected no cycling of expression in either the field or under diverse photoregimes in the laboratory. The timekeeping function of the clock has possibly been lost, enabling the midge to opportunistically exploit the unpredictable availability of permissive thermal conditions for growth, development, and reproduction during the short summer in Antarctica.
authors.affiliation: Departments of Entomology and Evolution, Ecology and Organismal Biology, Ohio State University, Columbus, OH 43210, USA.
authors.forename: Alena
authors.initials: A
authors.lastname: Kobelkova
authors.affiliation: Graduate School of Science, Osaka City University, Osaka 558-8585, Japan.
authors.forename: Shin G
authors.initials: SG
authors.lastname: Goto
authors.affiliation: Departments of Entomology and Evolution, Ecology and Organismal Biology, Ohio State University, Columbus, OH 43210, USA.
authors.forename: Justin T
authors.initials: JT
authors.lastname: Peyton
authors.affiliation: Graduate School of Science, Osaka City University, Osaka 558-8585, Japan.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Ikeno
authors.affiliation: Department of Zoology, Miami University, Oxford, OH 45056, USA.
authors.forename: Richard E
authors.initials: RE
authors.lastname: Lee
authors.affiliation: Departments of Entomology and Evolution, Ecology and Organismal Biology, Ohio State University, Columbus, OH 43210, USA. Electronic address: denlinger.1@osu.edu.
authors.forename: David L
authors.initials: DL
authors.lastname: Denlinger
mesh_terms: D000818:Animals; D000864:Antarctic Regions; D002683:Chironomidae / Q000235:genetics / Q000502:physiology*; D057906:Circadian Clocks; D003624:Darkness; D015870:Gene Expression; D007814:Larva / Q000235:genetics / Q000502:physiology; D008027:Light; D008124:Locomotion; D017440:Photoperiod; D012621:Seasons; D013696:Temperature
keywords: Circadian rhythms; Clock genes; Continuous light; Natural conditions; Polar biology