Identification of 74 cytochrome P450 genes and co-localized cytochrome P450 genes of the CYP2K, CYP5A, and CYP46A subfamilies in the mangrove killifish Kryptolebias marmoratus.

BACKGROUND: The mangrove killifish Kryptolebias marmoratus is the only vertebrate that reproduces by self-fertilizing and is an important model species in genetics and marine ecotoxicology. Using whole-genome and transcriptome sequences, we identified all members of the cytochrome P450 (CYP) family in this model teleost and compared them with those of other teleosts. RESULTS: A total of 74 cytochrome P450 genes and one pseudogene were identified in K. marmoratus. Phylogenetic analysis indicated that the CYP genes in clan 2 were most expanded, while synteny analysis with other species showed orthologous relationships of CYP subfamilies among teleosts. In addition to the CYP2K expansions, five tandem duplicated gene copies of CYP5A were observed. These features were unique to K. marmoratus. CONCLUSIONS: These results shed a light on CYP gene evolution, particularly the co-localized CYP2K, CYP5A, and CYP46A subfamilies in fish. Future studies of CYP expression could identify specific endogenous and exogenous environmental factors that triggered the evolution of tandem CYP duplication in K. marmoratus.