title: Molecular evolution of cryptochromes in fishes.
abstract: Circadian rhythmicity is an endogenous biological cycle of about 24h, which exists in cyanobacteria and fungi, plants and animals. Circadian rhythms improve the adaptability of organisms in both constant and changing environments. The cryptochrome (CRY) is a key element of the circadian system in various animal groups including fishes. We studied evolution of cryptochromes in the phylogenetically and ecologically diverse fish taxa. The phylogenetic tree of fish Cry features two major clades: Cry1 and Cry2. Teleosts possess extra copies of Cry1 due to the genome duplication, which resulted in 3 main paralogous subfamilies (1A, 1B and 1C). Cry1 experienced further diversification through additional duplications in some taxa. 1A of Cry1 is more conserved than the other paralogs (dN=0.010 ± 0.003, π=0.119 ± 0.058). The analysis of selection indicated that, while the Cry homologs in fish evolved under the different levels of selection pressure, strong purifying selection (average ω=0.017) dominated in their evolution.
authors.affiliation: Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, People's Republic of China.
authors.forename: Qiming
authors.initials: Q
authors.lastname: Mei
authors.affiliation: School of Biological Sciences, University of Hong Kong, Pokfulam Rd., Hong Kong, SAR, People's Republic of China.
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Sadovy
authors.affiliation: School of Biological Sciences, University of Hong Kong, Pokfulam Rd., Hong Kong, SAR, People's Republic of China; Department of Life Sciences, College of Science and General Studies, Alfaisal University, Riyadh, Saudi Arabia. Electronic address: vdvornyk@alfaisal.edu.
authors.forename: Volodymyr
authors.initials: V
authors.lastname: Dvornyk
mesh_terms: D000818:Animals; D002940:Circadian Rhythm / Q000235:genetics; D056931:Cryptochromes / Q000235:genetics*; D019143:Evolution, Molecular; D005399:Fishes / Q000235:genetics*; D020131:Genes, Duplicate / Q000235:genetics; D010802:Phylogeny
chemical_list: D056931:Cryptochromes
keywords: Circadian; Cryptochrome; Fish-specific genome duplication; Purifying selection; Reciprocal gene loss