Molecular Mechanism and Cellular Distribution of Insect Circadian Clocks

• Published in: Annual review of entomology Vol. 45; no. 1; pp. 769 - 793
• Main Author: Giebultowicz, Jadwiga M
• Format: Journal Article
• Language: English
• Published: Palo Alto, CA 94303-0139 Annual Reviews 01.01.2000; 4139 El Camino Way, P.O. Box 10139 Annual Reviews, Inc; USA
• Subjects: Animals; Biochemistry. Physiology. Immunology; Biological and medical sciences; Biological Clocks - genetics; Circadian Rhythm - genetics; circadian rhythms; Drosophila melanogaster; Drosophilidae; Fundamental and applied biological sciences. Psychology; Genes, Insect; Humans; Insecta; Insecta - genetics; Invertebrates; Malpighian tubules; period; Physiology. Development; sperm release; timeless; Semen; Insecta; Excretory system; Nervous system; Biological rhythm; Review; Circadian rhythm; Gene expression; Drosophilidae; Biological clock; Gene; Malpighian tube; Arthropoda; Invertebrata; Drosophila melanogaster; Diptera; Molecular clock
• ISSN: 0066-4170; 1545-4487
• DOI: 10.1146/annurev.ento.45.1.769

Circadian clocks are endogenous timing mechanisms that control molecular, cellular, physiological, and behavioral rhythms in all organisms from unicellulars to humans. Circadian rhythms influence many aspects of insect biology, finetuning life functions to the light and temperature cycles associated with the solar day. Genetic studies in the fruit fly Drosophila melanogaster have led to the cloning and characterization of several genes involved in the mechanism of the circadian clock. Periodic transcription and translation of these clock genes form the basis of a molecular feedback loop that has a "circa" 24-hour period. Rhythmic expression of clock genes in specific brain neurons appears to control behavioral rhythms in adult flies. However, clock genes are also expressed in other tissues, both within and outside of the nervous system. These observations prompted chronobiologists to investigate whether nonneural tissues possess intrinsic circadian clocks, what role they may be playing, and what the relationships are between clocks in the nervous system and those in peripheral tissues. Answers to those questions are providing important insights into the overall organization of the circadian system in insects.