Expression of a constitutive cytochrome P450 (CYP2K1) in livers of rainbow trout ( Oncorhynchus mykiss) embryo and sac-fry

Abstract

The hepatic expression of a recently reported cytochrome P450, P450 2K1 (CYP2K1), was studied in livers of rainbow trout ( Oncorhynchus mykiss) 30 day embryos (1 day before hatching) and 2 day and 10 day sac-fry at both the transcriptional and translational levels using a CYP2K1 cDNA probe (2K1,7c, 440 bp) and antibodies (polyclonal and monoclonal) against rainbow trout cytochrome P450 LMC2, the presumed translational product of the CYP2K1 gene, as probes for Northern and Western blots, respectively. The P450 LMC2 isoform was previously identified as a constitutive carcinogen-activating P450 present in the livers of adult rainbow trout. Simultaneous recovery of RNA, DNA and protein was accomplished by extraction of the same pooled liver tissues removed from the trout embryos and sac-fry by microdissection. The concentrations of both hepatic CYP2K1 mRNA and protein (LMC2) increased with embryo and sac-fry development. Comparison of the levels of the LMC2-like protein (translational expression of CYP2K1) using mouse anti-trout LMC2 monoclonal antibody (3M1) as a probe in 30 day embryo, 2 day sac-fry, 10 day sac-fry and 1-year-old trout liver yielded values of 0.035 pmol μg −1 DNA, 0.08 pmol μg −1 DNA, 0.12 pmol μg −1 DNA and 0.90 pmol μg −1 DNA, respectively.