Eumetazoan Cryptochrome Phylogeny and Evolution

farhan ananda murtono pratama;

Cryptochromes (Crys) are light sen sing receptors that are presentinall eukaryotes. They mainly absorb light in the UV/ blue spectrum. The extant Crysconsist of two subfamilies, which are descendants of photo lyases but are now involved in the regulation of circadian rhythms. So far, knowledge about the evolution, phylogeny,and expression of crygenesis stills carce. The inclusion of cry sequences from a wide range of bilaterian species allowed us to analyze their phylogeny indetail, identifying six major Crysubgroups. Selective gene inactivations and stabilizations inmultiple chordate as well as arthropod lineages suggest several sub-and/or neofunctionalization events. An expression study performed in zebrafish, themodel organism harboring the largest amount of crys,showed indeed only partially over lapping expression of paralogous mRNA, supporting gene sub-and/orneofunctionalization. Moreover, the daily cry expression in the adult zebrafish retina indicated varying oscillation patterns indifferent cell types. Our extensive phylogenetic analysis provides for the first time an overview of cry evolutionary history. Although several, especially parasitic or blind species, have lost all cry genes, crustaceans have retained up to three crys, teleosts possess up to seven, and tetrapods up to four crys. The broad and cyclic expression pattern of all cry transcripts in zebrafish retina llayer simplies aninvolvement in retinal circadian processes and supports the hypothesis of several autonomous circadian clocks present in the vertebrate retina