Studying Genetic Structure Among Cultured Populations And Screening Growth-related DNA Markers In Takifugu Obscurus

Takifugu obscurus, is one of the Takifugu species of river to sea migration inreproductive migratory behavior. It is a kind of economic and high nutritional value ofaquatic productsmainly and distributes in the east China sea, yellow sea and bohai seaarea. However, in recent years, development of the aquaculture has been slowed downdue to she Takifugu obscurus’s original and ecological environment worsening,theYangtze river hydrological conditions changed year by year, overfishing and otherreasons, so genetic improvement、germplasm resources and others are in the face.Thisstudy carried out the screening of gender-related molecular markers of rubrippes, andScreening growth-related DNA markers in Takifugu obscurus using SSR-BSA.They werepotential valuable geneticm arkers for marker assisted selection of tilapia.Firstly, this article systematically elaborated fish breeding techniques and itscurrent developments and analyzed the overview of the application of modernbiotechnology in fish breeding and addressed fish breeding trends, was designed toprovide a theoretical basis and reference for fish breeding of new varieties. It show thatestablishing advanced system of fish breeding and breeding innovation platform,improving the effect of fish genetic breeding and seed quality are important for thehealthy development of aquaculture industry.Secondly, characteristics of Takifuguobscurus were summarized from basic biology, reproductive biology, artificial breedingtechnology, ecology, toxins and other areas.We can see the research situtation ofTakifugu obscurus and the research emphasis and direction in the future, it is beneficial to fill the research blank of Takifugu obscurus and continue to study the scientificresearch of value.Using21paris of microsatellite primers to analyze the genetic variances betweenthree cultured populations of Takifugu obscurus and nineteen microsatellite markerswere amplified successfully. In three populations of Takifugu obscurus,the number ofalleles (A) was3~11with an average of6.58; the effective number of alleles (Ne) was1.7~7.8with an average of4.5; the value of average observed heterozygosities was0.1556~1.0000; the expected heterozygosities (He) was0.3993~0.8759and the PICranged from0.3533to0.8577. The mean polymorphic information content (PIC)followed the order of GZ, SH, JS. Genetic diversity coefficient were0.0481、0.0617、0.0755with an average of0.0808, there were moderate genetic differentiation amongthese three cultured populations. The genetic distance between GZ and JS is0.2039, GZand SH0.3508. The cluster analysis was carried out that three cultured populations werepooled into2groups: GZ, JS and SH. The results suggested that a low level ofpolymorphism information content and moderate genetic diversity in three populationsof Takifugu obscurus.In order to obtain more molecule marker slinked to growthrelated traits ofTakifugu obscurus，Microsatellites combined with bulked segregation analysis (BSA)were used to screen the gender differences of60individuals from a population ofTakifugu obscurus. Two classes with mixed DNA template of Takifugu obscurussamples were analyzed in85microsatellites loci. We found A total of14unique allelesfor each class in all the loci. Analysis and statistic of differential bands of individual，sbanding patterns show that locus TOP03、TOG01、fms15、fms75are negativelycorrelated with growth trait significantly, and the frequency of specific bands in “S”group is respectively63.33%、53.33%、33.33%and43.33%, correlation coefficient-0.553、-0.346、-0.333and-0.423; while the loci fms89, positively related and theFrequency of specific bands in “S” group is33.33%, correlation coefficient0.388. Butthe verification experiment show that locus fms15、fms75are negatively correlated withgrowth trait significantly among them fms15、fms75are of extreme significance at-0.411and-0.384. In this study, the microsatellite loci with a significant effect ongrowth traits were found, and could be used as a molecular marker to selected stocks of good growth performance. They were potential valuable geneticm arkers formarker assisted selection of tilapia.