GYNOGEN PRODUCTION IN HYBRID STRIPED BASS

Meiotic gynogens were produced using hybrid striped bass (female white bass, Morone chrysops, x male striped bass, M. saxatilis) eggs and wh ite perch M. americana UV-irradiated sperm. Diploidy of the fertilized eggs was restored by application of hydrostatic pressure, which induc ed retention of the second polar body. Use of white perch sperm provid ed an unmistakable marker for detection of a paternal genetic contribu tion. Two assays were developed using the polymerase chain reaction (P CR) to amplify specific regions of the Morone genome. Primers for gene amplification were developed based on the DNA sequence of the striped bass growth hormone gene (SB-GH) or an anonymous striped bass locus ( SB1-10). Control experiments using DNA from the three Morone species d emonstrated that gene amplification yielded species-specific patterns of DNA fragments for both of these loci. Therefore, any progeny with a paternal contribution of a set of white perch chromosomes could be id entified. Using these assays, we demonstrated that greater than 75% of the progeny obtained from successful experiments were true gynogens. These striped bass hybrid gynogens will provide the basis for future e fforts to calculate gene-centromere distances and to identify markers linked to specific traits of interest to aquaculture.