2 C-MYC GENES FROM A TETRAPLOID FISH, THE COMMON CARP (CYPRINUS-CARPIO)

Two c-myc genes have been isolated from a tetraploid fish, the common carp (Cyprinus carpio). The nucleotide (nt) sequences of the two genes and their flanking regions (CAM1, 8675 bp and CAM2, 5784 bp) have bee n determined. Both genes contain two coding exons which are homologs o f c-myc exons 2 and 3 in higher vertebrates. The nt sequence homologou s to c-myc exon 1 of higher vertebrates has not been found. Carp CAM1 and CAM2 presumably encode peptides of 394 and 401 amino acids (aa), r espectively. These two peptides share 55-91% aa identity with those of humans, chickens, frog, rainbow trout and zebra fish. The two carp c- Myc have a Glu stretch at the beginning region of exon 3. This Glu str etch is also present in zebra fish, suggesting that it may be characte ristic to c-myc genes of cyprinid fishes. The existence of two c-myc i n capp is attributed to the tetraploid nature of carp. These two genes share 92.4% nt identity in the coding region and 84.2% in the intron. The two deduced peptides shape 94.2% aa identity, suggesting that the tetraploid event probably occurred 58 million years ago. Both of the genes' cDNA clones were obtained from a cDNA library of carp periphera l blood leukocytes, implying that both of the genes are expressed.