Genetic And Sex-effect Analysis In The Breeding Populations Of Complete Set Lines In Chinese Mitten Crab(eriocheir Sinensis)

1.Genetic comparison and selection pressure analysis in complete set lines breeding populations of Chinese mitten crab(Eriocheir sinensis)In this paper, ten microsatellite loci was used to investigate the genetic variation and differentiation of complete set line breeding populations(parental lines A、B of selective F4 and their reciprocal crosses AB、BA) and a reference wild population(YZ) sampled from the Yangtze River Estuary. The results indicated that:(1) genetic diversities of reciprocal crosses were higher than these of their parents, but the mean genetic diversity of the four breeding populations was lower that of the wild populations.(2) the results of molecular variance analysis(AMOVA), NJ phylogentic tree based on Nei’ s genetic distance, principal components analysis(PCA) and STRUCTURE genetic cluster analysis consistently showed that there were significant differentiation(P<0.01) among three clusters, namely, AB and AA clustered one group, BA and BB clustered another group and YZ consisted of separated group.(3) According to selective pressure analysis in the Arlequin software and Bayescan software, three microsatellite loci in the breeding populations and one locus in the wild population were detected with significantly positive selection pressure, indicating the continuous strong artificial selection would have resulted in a high level of genetic differentiation between breeding and wild populations. In general, the artificial selection has decreased the genetic diversity withinbreeding populations and enlarged genetic differentiation between breeding and wild populations. Fortunately, the complete set line breeding could enrich genetic diversity of breeding populations.2.SNPs detecting in the myostain gene and their relationship with growth traits in the Chinese mitten crabMyostatin(MSTN), also called GDF-8, is a member of the transforming growth factor-β superfamily which negatively regulates growth of muscle tissue. In the study, the total of 120 the breeding Chinese mitten crab individuals were employed for polymorphisms screening in the MSTN gene and for evaluating of the association of MSTN gene with growth traits. The results indicated that: three nonsynonymous mutations were found(C714T、G729A、G753T, named SNP1、SNP2、SNP3, respectively)in the gene and they played a role in controlling growth traits, especially in SNP1. In which, the CC genotype would be positive correlation with traits and the TT genotype was negative correlation with growth traits. In general, the genotype combinations of TTíAAíTT had the highest effects on growth traits. Consequently, the MSTN gene would be used as a candidate in carrying out marker-assisted selection of breeding programs in Chinese mitten crab.3.Observation and analysis of growth dynamics and sex-effect in the breeding populations of Chinese mitten crabIn this study, we conducted the observation and analysis of five growth traits(body weight, carapace length, carapace width, carapace height, the length of the second pereiopod) in the breeding populations ofcompleted set lines in Chinese mitten crab within the 8 months(from April to October at its adult stage).The results showed that there were the same growth characteristics for the five growth traits, namely, there were fast growth during April to July as well as August to October, but relatively slow growth during July to August. There were high variation coefficients in body weight and condition factors in the each measured months, and also significantly relationship between traits in the each measured months. Male crab displayed significantly growth rate than female crab since July, and 10% higher of growth gain, condition factor and heterosis than female, indicating obvious sex effects on growth traits in mitten crab. The results gave a guideline for cultivation of mitten crab and presented basic data for sex effect study in other organisms.