DEVELOPMENT AND CHARACTERIZATION OF A RAINBOW-TROUT LIVER-CELL LINE EXPRESSING CYTOCHROME P450-DEPENDENT MONOOXYGENASE ACTIVITY

A cell line, RTL-W1, has been developed from the normal liver of an ad ult rainbow trout by proteolytic dissociation of liver fragments. RTL- W1 can be grown routinely in the basal medium, L-15, supplemented with 5% fetal bovine serum. In this medium, the cells have been passaged a pproximately 100 times over an 8-year period. The cells do not form co lonies ar grow in soft agar. The cultures are heteroploid. The cell sh ape was predominantly polygonal or epithelial-like, but as cultures be came confluent, bipolar or fibroblast-like cells appeared. Among the p rominent ultrastructural features of RTL-W1 were distended endoplasmic reticulum and desmosomes. Benzo[a]pyrene was cytotoxic to RTL-W1. Act ivity for the enzyme, 7-ethoxyresorufin 0-deethylase (EROD), which is a measure of the cytochrome P4501A1 protein, increased dramatically in RTL-W1 upon their exposure to increasing concentrations of either bet a-naphthoflavone (BNF) or 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). With these properties, RTL-W1 should be useful for studying the expres sion of the cytochrome P450 enzymes and as a tool for assessing the to xic potency of environmental contaminants.