MOLECULAR-BIOLOGY AND ENVIRONMENTAL INDUCTION OF PISCINE METALLOTHIONEIN

To investigate the factors involved in the control of metallothionein (MT) expression in fish, genomic clones encoding the MTs from the Cd-t olerant fish (pike and stone leach) were isolated. Sequencing revealed putative metal regulatory elements (MREs) in the 5'-regions of both M T genes. Comparison of their composition and location showed little di stinction between different fish species. However, although high overa ll homology exists between fish MTs and their mammalian counterparts, the 5'-regions of the fish genes are distinct, not only in the organis ation of their MREs but also in the absence of other transcription fac tor binding sites.