Estimates of Heritability and Genetic Correlations for Growth Traits in Chinese Shrimp Fenneropenaeus chinensis

[Objective] The aim was to estimate the heritability and genetic correlations of growth traits of Chinese shrimp Fenneropenaeus chinensis so as to provide basis and technical parameters for the breeding and selecting of Chinese shrimp.[Method] 51 full-sib families（including 35 half-sib families）of the Chinese shrimp F.chinensis were obtained by artificial insemination.Four growth traits of these families were measured,including body length,cephalothorax length,abdorminal segment length and body weight.According to quantitative genetics theory,the heritability of each growth trait,genetic and phenotypic correlation among these traits was statistically studied.[Result] The heritability was 0.36-0.51 for body length,0.14-0.24 for cephalothorax length,0.25-0.50 for abdominal segment length,and 0.04-0.29 for body weight.High and positive genetic correlations were obtained among growth traits.The genetic correlation between body weight and abdominal segment length was the highest（0.92）,followed by body length and abdominal segment length（0.91）,body length and body weight（0.88）,body weight and cephalothorax length（0.87）,abdominal segment length and cephalothorax length（0.86）,while the genetic correlation between body length and cephalothorax length was the lowest（0.83）.[Conclusion] The phenotypic correlation of body length,cephalothorax length,abdorminal segment length and body weight of Chinese shrimp F.chinensis were from 0.80 to 0.90 with extremely significant difference（P0.01）among the four growth traits by t-test.

Comparisons of Growth and Survival Performance Among Selected Families and Wild Populations of Fenneropenaeus chinensis

In this study,families of selected population for growth(SP_BWT),selected population for white spot syndrome virus(WSSV)resistance(SP_RW),Bohai wild population(WP_BH)and Huanghai wild population(WP_HH)of F.chinensis were constructed through artificial insemination and with the standardized procedure of larvae rearing.Growth and survival performance were studied among four populations after a 70 days common test.The results showed that the maximum least square mean of body weight was 17.50 g in SP_BWT while the minimum was 13.03 g in WP_HH.Compared with WP_BH,body weight of SP_BWT increased by 23.41%(P<0.01)and that of SP_RW by 12.20%(P>0.05).Body weights of SP_BWT and SP_RW were significantly higher than that of WP_HH,which increased by 34.31%(P<0.01)and 22.10%(P<0.05),respectively.The mean AGR of four populations was 0.19,0.18,0.17 and 0.16 g d^(-1),respectively.Coefficient of variation of body weight among four populations was high,which ranged from 32.67% to 35.25%.Such a range showed that there was the potentiality for further improvement in selected populations.Coefficient of variation of survival rate among four populations was low,varying between 3.20% and 5.90%.The difference of survival was highly significant(P<0.01)between SP_BWT and WP_BH,and significant(P<0.05)between SP_RW and WP_BH.However,no significant difference among other populations(P>0.05)was observed.Different growth performances were also observed among different families in each population.The body weight of 798F family was the highest.The absolute growth rate(AGR)was 0.25 g d^(-1),150%higher than that of the lowest one,0.1 g d^(-1) in 807F family.Survival rate of families among four populations was different.The highest was 94.74%,and the lowest was 71.88%.

应用BLUP法对中国对虾一代选择的遗传进展

为了评估中国对虾最佳线性无偏预测(Best liner unbiased prediction,BLUP)的育种效果,利用2005年评估的个体育种值,组建3个高育种值家系为实验组,3个平均值育种值家系为对照组,进行了生长对比测试。2006年,6个家系的苗种经过独立培育、中间暂养,体重达到1g左右时用荧光标记进行了标记,标记后的幼虾同时放养于对虾养殖池中。在生产养殖池中养殖63d后进行生长性状的测定。BLUP法预测结果显示,中国对虾一代选育后的预期遗传进展为0.78g,相对于选育前全群的平均值6.68g提高了约11.68%。实际对比测试结果表明,高育种值家系后代平均体重为21.55g,平均育种值家系的平均体重为19.03g,选育一代的体重提高13.28%。结果表明,BLUP育种技术对中国对虾生长性状的选育效果显著。

中国对虾与生长性状相关微卫星DNA分子标记的初步研究

利用分群分离分析法对中国对虾(Fenneropenaeus chinensis)人工选育生长快的第6代群体生长性状发生分离的群体进行了微卫星DNA的遗传分析。7个多态性微卫星位点对分离群的大个体组和小个体组扩增时产生7个片段表现差异,扩增片段大小为0.1～1.0kb之间。同时对中国对虾人工选育的生长快群体4个连续世代进行了验证,扩增的结果显示,7个微卫星位点在4个连续世代中大部分的扩增带出现的频率相近,但是有一些扩增片段的基因频率出现差异,这些等位基因频率或增或减,这是否可作为具有良好生长特性的人工定向选育群体的遗传标记尚有待进一步研究。

中国对虾生长性状遗传参数的估计

通过人工授精的方法建立了中国对虾21个半同胞家系(47个全同胞家系)。测量了中国对虾21个半同胞(47个全同胞)家系的体长、头胸甲长、头胸甲宽、第2和第3腹节处宽、第2和第3腹节处高、第1腹节长、第6腹节长和体重,共测量中国对虾1387尾。采用混合家系材料,利用Mtd-freml软件中的动物模型进行分析,平均体重作为协变量,得到的生长性状遗传力在0.04～0.20。体重遗传力为0.14±0.16。体长的遗传力为0.10±0.06,头胸甲长为0.07±0.06,头胸甲宽为0.05±0.04,第2、3腹节宽为0.20±0.16,第2、3腹节高的最低为0.04±0.13,第1腹节长为0.09±0.09,第6腹节长为0.19±0.15。各个性状间表现出高的正相关,其中头胸甲宽和体长以及2.3腹节高的遗传相关最大,达到了1.0±0.01,第1腹节长和2.3腹节宽的遗传相关最小为0.82±0.08。遗传力估计结果表明,中国对虾体长、体重性状的遗传力属于中度遗传力,在加性效应控制下,对中国对虾生长性状进行选择育种具有很大的遗传改良潜力,可以获得较好的选择效果。性状间高遗传相关说明在对体重进行选择的同时,其余的生长性状可以获得相关的间接选择反应。通过性状间的相关关系研究,可以对两性状间的关系进行明确的定量,有利于制定合理的多性状选择方案。在实际育种工作过程中,可以排除一些不利的或者相关性小的性状,以达到目的性状的最佳选择进展。实验结果为中国对虾的间接选择和早期选择育种提供依据。

中国对虾生长性状相关遗传标记的筛选与克隆

采用随机扩增多态性DNA(RAPD)技术,对中国对虾“黄海1号”快速生长的第6代群体同一养殖池中生长性状发生分离的两个极端群体、海捕的中国对虾对照群体,进行生长相关遗传标记的筛选。采用240个RAPD引物,共产生标记数2156个。筛选出与生长性状相关的遗传标记65个,其中正相关标记55个,负相关标记10个。依据这些标记在群体中出现的频率和变化规律,筛选出9个特异性标记,其中正相关标记7个,负相关标记两个。对这些特异性标记进行序列测定,获得了6个完整的DNA序列(Genebank注册号DQ185932-DQ185937),并将测序结果进行BLAST分析,发现测得DNA的序列与数据库中已注册序列的相似性较低,未能找到同源性较高的功能基因。根据每一序列重新设计引物,已有两个RAPD标记成功转化为稳定的SCAR标记。