GENOMIC IDENTIFICATION OF CATFISH SPECIES BY POLYMERASE CHAIN-REACTION AND RESTRICTION ENZYME ANALYSIS OF THE GENE ENCODING THE IMMUNOGLOBULIN-M HEAVY-CHAIN CONSTANT-REGION

Nuclear DNA was isolated from the blood cells of catfish representing three families (clariidae, pangasiidae and ictaluridae) for analysis b y polymerase chain reaction (PCR) and restriction enzymes. Primers spe cific for the CH4, exon of the gene encoding the immunoglobulin M heav y chain of channel catfish (Ictalurus punctatus) were used. Nuclear DN A amplified with these primers yielded a single band of about 300 base pairs (bp) for Clarias macrocephalus, Pangasius gigas, Pangasius hypo phthalmus and the hybrid of P. gigas X P. hypophthalmus. However, the same primers yielded two DNA bands of about 300 and 340 bp in Clarias gariepinus and in the hybrid of C. macrocephalus X C. gariepinus. Nucl eotide sequences of the amplified DNA were determined for I. punctatus , C. macrocephalus, P. gigas and P. hypophthalmus. Based on the DNA se quence data, the restriction enzyme HpaI was used to further character ize the PCR products of P. gigas, P. hypophthalmus and their hybrid. D igestion with this restriction enzyme yielded one DNA band (300 bp) fo r P. gigas, two bands (100 and 200 bp) for P. hypophthalmus and three bands (100, 200 and 300 bp) for the hybrid. These findings would aid i n identifying genetic contributions in hybrid, androgenetic, gynogenet ic and polyploid catfish. (C) 1997 Elsevier Science B.V.