Shirak, A., Lab. of Fish Immunology/Genetics, Faculty of Life Sciences, Bar Ilan University, Ramat Gan 52900, Israel
Avtalion, R.R., Lab. of Fish Immunology/Genetics, Faculty of Life Sciences, Bar Ilan University, Ramat Gan 52900, Israel

Fertilization of Oreochromis aureus eggs with UV-irradiated sperm from the closely related species O. niloticus, followed by diploidy restoration, produced offspring with lower embryo viability and higher skeletal deformation rates than siblings generated with sperm from a genetically distant species (Tilapia zillii). Results showed that: (a) deleterious effects due to O. niloticus sperm accumulate in gynogenetic fish over generations; (b) such effects are eliminated when using T. zillii sperm to fertilize eggs from gynogenetic mothers produced by full-sib matings. These results suggest that: (a) deleterious effects are associated with residual male DNA fragments which may be passed on to descendent offspring; (b) such fragments are significantly purged following full-sib mating. These findings suggest that biparental reproduction may play an important role in the control of genome integrality by purging supernumerary chromosome fragments.