Investigation on dispermic androgenesis in sturgeon fish. The first successful production of androgenetic sturgeons with cryopreserved sperm

Induced diploid androgenesis is considered as a valuable tool for restoration of endangered or extinct species from cryopreserved spermatozoa. The method of dispermic androgenesis was developed in sturgeon fishes whose threatened status requires urgent conservation efforts. The method includes genetic inactivation of eggs, their insemination with concentrated sperm (to cause polyspermy), and the heat shock that facilitates the fusion of male pronuclei. Restoration of diploid state of androgenotes by fusion of two sperm nuclei allows androgenetic progeny to have a heterozygosity level as similar as in a regular crossing. Using this method, viable androgenetic progenies were obtained for the first time in the Siberian, Russian, stellate, and beluga sturgeons. Then a number of androgenetic nucleocytoplasmic hybrids was obtained. Androgenetic hybrids were shown to have nuclear DNA of paternal species and mitochondrial DNA of maternal species. The first experiments in which cryopreserved sperm was used have demonstrated that dispermic androgenesis may be applied to restore sturgeons from their cryopreserved spermatozoa. Haploid androgenesis was also used to examine whether cryopreservation procedures cause lesions in DNA of sturgeon spermatozoa.