Mingkwan Mingmuang

Genomic identification of catfish species by polymerase chain reaction and restriction enzyme analysis of the gene encoding the immunoglobulin M heavy chain constant region

Abstract Nuclear DNA was isolated from the blood cells of catfish representing three families (clariidae, pangasiidae and ictaluridae) for analysis by polymerase chain reaction (PCR) and restriction enzymes. Primers specific for the CH 4 exon of the gene encoding the immunoglobulin M heavy chain of channel catfish ( Ictalurus punctatus ) were used. Nuclear DNA amplified with these primers yielded a single band of about 300 base pairs (bp) for Clarias macrocephalus, Pangasius gigas, Pangasius hypophthalmus 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 . Nucleotide sequences of the amplified DNA were determined for I. punctatus, C. macrocephalus, P. gigas and P. hypophthalmus . Based on the DNA sequence data, the restriction enzyme Hpa I was used to further characterize the PCR products of P. gigas, P. hypophthalmus and their hybrid. Digestion with this restriction enzyme yielded one DNA band (300 bp) for 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 in identifying genetic contributions in hybrid, androgenetic, gynogenetic and polyploid catfish.