METALLOTHIONEIN GENE-EXPRESSION IN ARCTIC CHAR (SALVELINUS-ALPINUS) FOLLOWING METAL AND PCB EXPOSURE

Full length sequences of two Arctic char (Salvelinus alpinus) metallot hionein (MT) cDNAs, corresponding to MT-A and MT-B, were isolated from a lambda-ZAP hepatic cDNA library. The two MT isoforms showed high si milarity to rainbow trout and Atlantic salmon MT, with the coding sequ ences being 100% homologous to rainbow trout MT. Following characteriz ation the MT cDNA was used to study the inducibility of Arctic char MT mRNA. Basal level expression was determined for 11 different tissues and it was observed that liver and immature gonads expressed the highe st levels of MT mRNA. The inducibility, of MT mRNA, by cadmium, 17 bet a-estradiol (E2) and three PCBs (2',4',6'-thichloro-3-biphenylol, 2,2' ,4,6,6'-pentaCB and 2,3,3',4,4',5',6-heptaCB) was thereafter determine d for liver, kidney and brain. While cadmium induced MT gene expressio n in all three organs, E2 treatment did not affect the MT mRNA levels. All three PCBs were found to result in reduced basal level MT mRNA ex pression. (C) 1998 Elsevier Science Ltd. All rights reserved.