CLONING OF THE P53 TUMOR-SUPPRESSOR GENE FROM THE JAPANESE MEDAKA (ORYZIAS-LATIPES) AND EVALUATION OF MUTATIONAL HOTSPOTS IN MNNG-EXPOSED FISH

A full-length cDNA clone of the medaka (Oryzias latipes) p53 tumor sup pressor gene was isolated from a cDNA library from adult liver tissue? sequenced and characterized. Sequence analysis revealed a high degree of homology between putative functional domains of medaka p53 and p53 genes from other vertebrate taxa including rainbow trout (Oncorhynchu s mykiss), frog (Xenopus laevis), chicken (Gallus gallus), rat (Rattus norvegicus), mouse (Mus musculus), hamster (Mesocricetus auratus), gr een monkey (Ceropithecus aethiops) and human (Homo sapiens). A single 1.9-kb p53 mRNA is expressed at a very low level in normal adult liver tissue. This transcript is similar in size to transcripts of p53 gene s from other species. Preliminary screening of six MNNG-induced tumors in four adult medaka revealed no mutations within characteristic muta tional hotspots encompassing conserved domains IV and V. (C) 1997 Else vier Science B.V.