The Evolution of Circadian Clocks in Insects

Meeting Abstract

S4.8  Monday, Jan. 5  The Evolution of Circadian Clocks in Insects MERLIN, C.*; REPPERT, S.M.; UMass Medical School; UMass Medical School

The molecular mechanism of circadian clocks has evolved independently several times over the course of evolution. However, within insects, in which circadian clocks regulate key daily and seasonal aspects of physiology and behavior, it appears that a single clockwork mechanism evolved that has undergone specialized changes in various lineages, through the processes of gene duplication and loss. The intracellular clockwork mechanism involves transcriptional feedback loops that drive persistent rhythms in mRNA and protein levels of key clock components. Within holometabolous insects, a molecular clock mechanism has been most extensively studied in the fruit fly Drosophila melanogaster, the housefly Musca domestica, the monarch butterfly Danaus plexippus, and the Chinese oak silk moth Antheraea pernyi, with more limited studies in the commercial silkworm Bombyx mori, the honeybee Apis mellifera, and the beetle Tribolium castaneum. Hemimetabolous insects, like cockroaches, locusts and crickets, have been the subjects of intensive behavioral studies of the circadian clock, but less in known about its molecular control, because genetic resources in these species are not yet available. Studies in the monarch butterfly have expanded our knowledge of the diversity of clockwork mechanisms within insects with the discovery of two functionally distinct, clock-relevant cryptochrome proteins. The ancestral clock of the butterfly provides a model for comparison of clockwork mechanisms among insects, and between insects and mammals.

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