CLONING AND SEQUENCING OF CDNAS OF THE BETA-GLOBIN GENE FAMILY IN CARP

A total blood cell cDNA library was constructed using a 3-year-old car p Cyprinus carpio. A beta-globin cDNA (C beta G1) was identified from the library by the polymerase chain reaction using a beta-globin-speci fic primer deduced from the carp beta-globin-A amino acid sequence. Al so, five additional types of beta-globin cDNAs (C beta G2 similar to 6 ) were isolated by colony hybridization using C beta G1 as a probe. Se quence analysis revealed that these C beta Gs encoded 147 amino acids, and the deduced amino acid sequences showed high identity (89.1-95.2% ) to previously reported carp beta-globin amino acid sequences. The nu cleotide sequences of the C beta Gs were very similar (identity 96.0-9 9.6%) and the expression levels of C beta G1 similar to 6 were 28.6, 2 8.6, 21.4, 14.3, 3.6 and 3.6% of the total number of cloned C beta Gs, respectively. Although the complete amino acid sequence identities be tween the C beta Gs and the beta-globin of higher vertebrates were low , functionally important regions such as the alpha-beta contact region and haem contact region were well conserved. These data showed that, as in higher vertebrates, the adult carp has a multiple beta-globin ge ne family (at least six members). However, transcripts encoding types of peptides (C beta G1 type, C beta G2 and 3 type, C beta G5 type, and C beta G4 and 6 type) were expressed at relatively high levels, this being a unique character of the carp haemoglobin system. (C) 1997 The Fisheries Society of the British Isles.