Xenobiotic biotransformation enzyme gene expression in early larval stages of plaice

cDNA probes were utilised to determine the pattern of expression of genes coding for pollutant biotransformation enzymes and systems for detoxication of peroxidation products in eggs and the early stages of plaice larval development. The presence of mRNAs for metallothionein and glutathione S-transferase in eggs indicates that the potential for oxidative defence may be present in fertilised eggs. Genes for the enzymes non-specific carboxylesterase and phenol UDP-glucuronosyl transferase, which have roles in the metabolism of endobiotic substances as well as pollutants, showed a peak in expression at hatch. CYP1A was expressed at hatch and the mRNA levels increased by about four-fold by 20 d post-hatch indicating the potential for metabolic activation of toxic polyaromatic compounds at the earliest free-living stages.