Diversity of cytochrome P450 2 family genes in non-mammalian vertebrates

The diversity and multiplicity of CYP2 genes in early diverging vertebrates were assessed using RT-PCR to identify sequences in an elasmobranch (dogfish: Squalus acanthias), a teleost (scup: Stenotomus chrysops), an amphibian (mudpuppy: Necturus maculosus), a reptile (turtle: Chrysemys picta) and a bird (chicken: Gallus gallus). Sixteen novel sequences were amplified using total RNA from liver of dogfish, turtle, mudpuppy and chicken. Two turtle sequences, four mudpuppy sequences and one dogfish sequence clustered with frog CYP2Q and chicken CYP2H genes. One turtle sequence grouped with CYP2E. A new chicken CYP2 clustered with rat CYP2B, CYP2G and CYP2A and trout CYP2M. A dogfish sequence and a turtle sequence grouped with CYP2D and CYP2K. Eight additional sequences were amplified from scup liver, intestine, brain and heart; these all grouped in a CYP2J/2N/2P clade. One sequence, prov. scup CYP2N3 (but possibly a CYP2N1 orthologue), was isolated from scup heart, gut, liver and brain. In the brain, cDNAs were amplified from the olfactory lobe, medulla, infundibulum and pituitary. One sequence was most highly expressed in the pituitary, where it may function in some aspect of hormonal control. Distinct CYP2P-related sequences were isolated from scup liver (prov. CYP2P4) and heart (prov. CYP2P5). Addition-al sequences from scup heart and brain RNA also grouped within this clade but could not be assigned to a subfamily. These results greatly expand the number of non-mammalian CYP2 genes known. Non-mammalian sequences may help to define CYP2 subfamily relationships and to identify conserved groups and functions. [Support: Sea Grant NA46RG0470, R/P60.]