Molecular and immunologic characterization of gynogenetic channel catfish (Ictalurus punctatus)

Second-generation gynogenetic channel catfish were characterized by molecul ar and immunologic assays to determine if they were isogenic at major histo compatibility complex loci. Southern blot analyses, using channel catfish M HC class II B and class I A gene probes, revealed identical banding pattern s among second-generation gynogenetic fish. In contrast, banding patterns f rom outbred fish differed not only from gynogenetic animals, but also among themselves. Nucleotide sequence analysis of the MHC class II beta(1) domai n, which encompasses the peptide binding region, from four randomly selecte d gynogenetic fish showed a single DNA sequence. In contrast, analysis of t he same region from three outbred fish showed sequences that differed not o nly among themselves, but also from those of gynogenetic animals. In cytoto xic assays, peripheral blood leukocytes from outbred fish lysed both gynoge netic and allogeneic targets, whereas those from gynogenetic fish lysed onl y allogeneic targets. Taken together, these results suggest that this group of second-generation gynogenetic channel catfish is isogenic at MHC loci a nd may provide an excellent system with which to study cell-mediated immuni ty in teleosts.