ANALYS IS ON THE GENETIC INFLUENCE OF HETEROLOGOUS SPERM IN THE GENOME OF GYNOGENETIC GRASS CARP

Grass carp, Ctenopharyngodon idellus, is one of the most important freshwater fish cultivated in China.Pure linesor highly pure inbred lines have to be generated for selecting geneswith desired economical characters during the breedingof grass carp and to avoid genetic separation that could degenerate the population character.Since the sexually maturationof grass carp needsmore than 4 years, to obtain a pure line of grass carp by sib matingwould take several decades and require much of labor and material resources.Modern artificial gynogenetic technology p rovides a rap id and economic way toestablish pure line or highly pure inbred line of grass carp.By inducing the gynogenetic development ofmature grass carpeggs with UVirradiated heterologous sperm and then inhibiting the first cleavage or the second polar body release of thegynogenetic eggs, absolute pure dip loid individual or very highly pure dip loid individual could be obtained.After the maturation of the gynogenetic individuals, by reinducing the gynogenesis ofmature eggs from a gynogenetic individual, absolutepure line or highly pure inbred line of grass carp could be generated.The genetic and developmental impact of the UVirradiated heterologous sperm on artificial gynogenetic fish, however, it remains a subject of debate in the fish artificial gynogenetic studies.In order to determine the genetic influence of heterologous sperm in the genome of artificial gynogenetic grass carp, genomes of artificially induced gynogenetic grass carp and their parents were comparatively analyzed with the techniques ofrandom amp lification polymorphism DNA (RAPD) and microsatellite analysis.The.4 gynogenetic grass carp individualsused in the examination is from a twogeneration artificially induced gynogenetic grass carp group (meiogynogeneticgroup) , in which all the individuals share an identical gene type.The mother of this meiogynogenetic group is an individual from a onegeneration artificially induced gynogenetic grass carp group (meiogynogenetic. group ).Chromosomeanalysis p rovided that there is no chromosome or chromosomal fragments of the heterologous sperm in the metaphase of themeiogynogenetic. grass carp group.Pure mother could simp lify ascertaining the heritable origin of gene loci in the gynogenetic grass carp.The p seudofather of the meiogynogenetic group is a common carp and its sperm being irradiated byUV before used for activating the matured eggs of grass carp.With.0 polymorphic random p rimers, total.04 RAPD lociwere detected in both the genomes of the meiogynogenetic group and their grass carp mother, and.03 loci in the paternal common carp. In microsatellite survey with 7 pairs ofmicrosatellite p rimers, 4 microsatellite loci in both of the meiogynogenetic grass carp group and their grass carp mother,and in their paternal common carp were detected respectively.On one RAPD locus, through the PCR p roducts of themeiogynogenetic grass carp group could not be distinguished from that of the paternal common carp by their length, obvious differenceeswere observed in their nucleotide sequences.Genetic similarity analysiswas 0.9903 to..000 between themeiogynogenetic grass carp group and the meiogynogenetic. grass carp mother, but 0.000 between the meiogynogenetic grass carp group and the paternal common carp.These results indicated that no locus of the detected lociwas identicalin gynogenetic grass carp and paternal common carp, the genetic materials of the heterologous sperm did not contaminatethe genome of the meiogynogenetic grass carp group and the genetic materials of common carp sperm could be comp letely destroyed by p roperly UVirradiation.