Establishment And Genetic Effects Analysis Of Platichthys Stellatus And Establishment Of Gynogenetic Family And Sex-induced Transformation

Starry flounder(Platichthys stellatus)is one of the important cultured marine flounder-fish species with high commercial development value,after half-smooth tongue sole,turbot and Paralichthys olivaceus,for the strong adaptability to the change of water temperature and salinity.It has high economic value and is suitable for intensive breeding.Artificially induced gynogenesis is one of the important techniques for sex control in aquatic animals,and for the culture of genetic breeding colony as well.In order to benefit the genetics and breeding of fish species,these items were studied in this paper including: Establishment of starry flounder family and identification of genetic parameters;Cryopreserved sperm of Lateolabrax japonicus was UV-irradiated and fertilized with Platichthys stellatus eggs.Gynogenetic diploid was induced by using cold and hydrostatic pressure shock and the induced pseudo-males with methyl testosterone.The mainly research results are as follows: 1.Establishment of starry flounder family and identification of genetic parametersThere were 25 successful cross combinations,which reproduced 29 families with the starry flounder from4 cultural populations.After 3 months culture,the weight,full length,body length and width of starry flounder were measured.Variance components were evaluated by using the minimum norm quadratic unbiased estimator.Results showed that Narrow heritability was 0.14-0.15,while broad heritability was 0.37-0.39.Additive genetic effects analysis showed that 3 mother and 4fathers were extremely significantly positive in these 4traits.Dominant random effects analysis showed that D2*20?D4*18 ?D5*26 ?D8*31?D9*30 ?D11*33cross combinations were extremely significantly positive.All these results first provided abundant genetic data for the selection of good parents and cross combinations in the family lines establishment and seed culture of the starry flounder.2.The induction of gynogenetic diploid and artificially induced sex-reversal in starry flounderArtificial induction of gynogenetic development involves two key techniques: sperm inactivation and prevent extrusion of the second polar body.In this study,cryopreserved sperm of Lateolabrax japonicus was UV-irradiated and fertilized with starry flounder eggs.Gynogenetic diploid was induced by using cold and hydrostatic pressure shock.The results of experiments showed that gynogenetic diploid can be induced by inactivated heterogenous sperm because that hybrid and haploid would die before hatching.Diploid gynogenesis was induced by activating egg development with UV irradiated sperm(80 mJ /cm2),cold shocks starting at 5min after fertilization,at-1.5? for 45 min durations or 5 min after fertilization,(13-14?),and then 60 MPa pressure treatment for 6 min.3.Sexual induction of gynogenetic diploidUsing C=1mg/m3 methyl testosterone treatment for a period of 50 days to starry flounder gynogenetic larvae,3 months of larvae in the growth and histological observation,successfully obtained the pseudo-male.4.The embryonic developing comparation of gynogenetic diploid,haploid and hybridization in starry flounderArtificially induced gynogenesis is one of the important techniques for sex control in aquatic animals,and for the culture of genetic breeding colony as well.In this study,cryopreserved sperm of Lateolabrax japonicus was UV-irradiated and fertilized with Platichthys stellatus eggs.Meanwhile,P.stellatus eggs fertilized with UV-irradiated L.japonicas sperm but without cold or hydrostatic pressure shock were set as the haploid group,P.stellatus eggs fertilized with L.japonicas sperm were set as the hybridized group,and P.stellatus eggs fertilized with P.stellatus sperm were set as the control group.Results showed that cell division started at the similar time point in the control group with in haploid,hybridized and gynogenetic embryos,however,the embryonic development of the three experimental groups retarded from the late blastula stage if compared with that of the control group.All the hybridized embryos died before the formation of embryonic body.All the haploid embryos died before heart beat started.The development of the gynogenetic diploids was followed the similar pattern with that of the control group while only(2.17±0.01)% of gynogenetic diploids were hatched at 104 h 50min with(53.59±0.36)% malformed.In this study,provide abundant cytobiological evidence for researches in the developmental biology of haploid,hybridized,and gynogenetic embryos of this species.