Establishment and Identification of Mitotic Gynogenesis Japanese Flounder(Paralichthys olivaceus) Pure Family

In order to facilitate the selective breeding process of Japanese flounder(Paralichthys olivaceus)and obtain the pure family with desirable traits,we employed the cryo- preserved Sea perch(Lateolabrax japonicus)sperm and a flounder family generated in 2007 as experimental materials in this work,which established flounder pure familys with mitotic gynogenesis,analyzed the ploidy and monitored genetic markers.The results from mitotic gynogenesis suggested:In 17 ℃ water,inactivating sea perch sperm in 58 min after fertilization,followed by 6 min of hydrostatic pressure(590 kg/cm2),led to a higher rate of induction(32.30±3.34)%.Detection on three types of embryos(haploid,mitotic gynogenesis and normal diploid)by flow Cytometer showed that the relative amounts of DNA were 17.07(mode:17)in the haploid,27.75 in mitotic gynogenesis(mode:27)and 25.63(mode:27)in normal diploid.When the two familys(mitotic gynogenesis family and inbreeding family)were compared,their growth difference was significant.The average weight of inbreeding group was about(48.89 ± 17.01)g at 6- month fish,while the weight of gynogenetic family was(22.09±6.94)g.Thirty microsatellite markers were used to analyze the inbreeding and gynogenetic familys,the data indicated that all microsatellite sites showed heterozygous gene polymorphism in inbreeding group and 24 loci were with polymorphism in the mitotic gynogenesis group.In parallel,the chisquare test was used and the results implied that the segregation rate was in accordance with the 1∶1(alleles).The genetic similarity between inbreed group and gynogenesis group was 0.813 9,while the genetic distance was 0.205 9.It was concluded that mitotic gynogenesis familys can be generated via usage of cryo-preserved sea perch sperm,which provides the theoretical basis for establishing superior Japanese flounder familys.