Dispermic Androgenesis as a Method for Recovery of Endangered Sturgeon Species

Abstract

The possibility of the recovery of endangered sturgeon species is considered, with special reference to the production of androgenetic nucleocytoplasmic hybrids by dispermic androgenesis. The method of dispermic androgenesis, developed for sturgeon fishes, includes genetic inactivation of eggs, their insemination with concentrated sperm (to cause polyspermy), and heat shock to facilitate the fusion of male pronuclei. The restoration of the diploid state of androgenotes by fusion of two sperm nuclei allows androgenetic progeny to have a heterozygosity level similar to that in a regular crossing. Using this method, viable androgenetic progenies of several sturgeon species were obtained for the first time. Here we present the results of the first successful experiments in obtaining androgenetic hybrids in sturgeon fishes by dispermic androgenesis. Both the androgenetic hybrids, between stellate and great sturgeons and between Persian and Russian sturgeons, obtained in these experiments were fully viable. It was shown that androgenetic hybrids had the nuclear DNA of the paternal species and the mitochondrial DNA of the maternal species. The morphological analysis proved the androgenetic hybrids between Persian and Russian sturgeons to be completely identical to the paternal species at the age of 12 months, and those between stellate and great sturgeons by 3 years. The prolonged manifestation of matrocliny observed in both hybrids is most likely related to the extended life cycle of acipenserids. Our results suggest that endangered sturgeon fishes may be recovered by means of dispermic androgenesis if the sperm alone of a given species is available.