title: Clock gene evolution and functional divergence.
abstract: In considering the impact of the earth's changing geophysical conditions during the history of life, it is surprising to learn that the earth's 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.
authors.affiliation: Department of Genetics, University of Leicester, Leicester, UK.
authors.forename: Eran
authors.initials: E
authors.lastname: Tauber
authors.forename: Kim S
authors.initials: KS
authors.lastname: Last
authors.forename: Peter J W
authors.initials: PJ
authors.lastname: Olive
authors.forename: C P
authors.initials: CP
authors.lastname: Kyriacou
mesh_terms: D056930:ARNTL Transcription Factors; D000595:Amino Acid Sequence; D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins; D001683:Biological Clocks; D005075:Biological Evolution; D056926:CLOCK Proteins; D002453:Cell Cycle; D000458:Cyanobacteria / Q000502:physiology; D018534:Earth, Planet; D019143:Evolution, Molecular; D005580:Fossils; D055593:Geological Phenomena; D005844:Geology; D008957:Models, Genetic; D008969:Molecular Sequence Data; D010802:Phylogeny; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D013997:Time Factors; D015534:Trans-Activators / Q000502:physiology; D014157:Transcription Factors / Q000502:physiology
chemical_list: D056930:ARNTL Transcription Factors; D051792:Basic Helix-Loop-Helix Proteins; D056926:CLOCK Proteins; D015534:Trans-Activators; D014157:Transcription Factors