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Clock Gene Evolution and Functional DivergenceDepartment of Genetics, University of Leicester, Leicester UK
Department of Marine Sciences and Coastal Management, University of Newcastle upon Tyne, UK
Department of Marine Sciences and Coastal Management, University of Newcastle upon Tyne, UK
Department of Genetics, University of Leicester, Leicester UK, cpk{at}leicester.ac.uk In considering the impact of the earths changing geophysical conditions during the history of life, it is surprising to learn that the earths rotational period may have been as short as 4 h, as recently as 1900 million years ago (or 1.9 billion years ago). The implications of such figures for the origin and evolution of clocks are considerable, and the authors speculate on how this short rotational period might have influenced the development of the "protoclock" in early microorganisms, such as the Cyanobacteria, during the geological periodsin which they arose and flourished. They then discuss the subsequent duplication of clock genes that took place around and after the Cambrian period, 543 million years ago, and its consequences. They compare the relative divergences of the canonical clock genes, which reveal the Per family to be the most rapidly evolving. In addition, the authors use a statistical test to predict which residues within the PER and CRY families may have undergone functional specialization.
Key Words: circadian ultradian evolution Cyanobacteria cell cycle earth rotation functional divergence
Journal of Biological Rhythms, Vol. 19, No. 5,
445-458 (2004) This article has been cited by other articles:
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