Gynogen Production in Hybrid Striped Bass

Abstract.— Meiotic gynogens were produced using hybrid striped bass (♀ white bass, Morone chrysops , ×♂ striped bass, M. saxatilis ) eggs and white perch M. americana UV-irradiated sperm. Diploidy of the fertilized eggs was restored by application of hydrostatic pressure, which induced retention of the second polar body. Use of white perch sperm provided an unmistakable marker for detection of a paternal genetic contribution. Two assays were developed using the polymerase chain reaction (PCR) 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 (SBI-10). Control experiments using DNA from the three Morone species demonstrated 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 identified. 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 efforts to calculate gene-centromere distances and to identify markers linked to specific traits of interest to aquaculture.