大菱鲆体重和形态性状的遗传动态分析

In order to elucidate the genetic mechanism of growth traits in turbot during ontogeny, developmental genetic analysis of the body weights, total lengths, standard lengths and body heights of turbots was conducted by mixed genetic models with additive-dominance effects, based on complete diallel crosses with four different strains of Scophthalmus maximus from Denmark, Norway, Britain, and France. Unconditional genetic analysis revealed that the unconditional additive effects for the four traits were more significant than unconditional dominance effects, meanwhile, the alternative expressions were also observed between the additive and dominant effects for body weights, total lengths and standard lengths. Conditional analysis showed that the developmental periods with active gene expression for body weights, total lengths, standard lengths and body heights were 15–18, 15 and 21–24, 15 and 24, and 21 and 27 months of age, respectively. The proportions of unconditional/conditional variances indicated that the narrow-sense heritabilities of body weights, total lengths and standard lengths were all increased systematically. The accumulative effects of genes controlling the four quantitative traits were mainly additive effects, suggesting that the selection is more efficient for the genetic improvement of turbots. The conditional genetic procedure is a useful tool to understand the expression of genes controlling developmental quantitative traits at a specific developmental period(t-1→t) during ontogeny. It is also important to determine the appropriate developmental period(t-1→t) for trait measurement in developmental quantitative genetic analysis in fish.     

大菱鲆（Scophthalmus maximus）不同生长阶段体重的遗传参数和育种值估计

采用非求导约束最大似然法（DFREML）进行了大菱鲆不同生长阶段体重的遗传参数和育种值研究,每一生长阶段分别对4种不同动物模型估计遗传参数的差异进了比较。不同模型中对全同胞家系效应和日龄协变量作了不同的考虑：模型A,不考虑全同胞家系效应和日龄协变量;模型AD,仅考虑日龄协变量;模型AF,仅考虑全同胞家系效应;模型AFD,同时考虑全同胞家系效应和日龄协变量。结果表明,6月龄利用模型AF,3月龄、9月龄、12月龄、15月龄利用模型AFD对遗传参数和育种值进行估计较为适合。利用育种值选择和表型值选择两种方法分别进行了家系选择和个体选择的效率比较,结果表明,在每一生长阶段依据育种值选择的效率均高于表型值选择的效率。利用不同生长阶段的家系育种值以及亲本育种值分别进行了家系选择比较和亲本选择比较,结果表明,在不同生长阶段,按家系、父本和母本的育种值分别排序,前50％的相同率和育种值的相关系数均为9-12月龄较6—9月龄的提高幅度比其它相邻阶段显著增加,推测家系提前筛选的时间以及父本和母本选择的时期均不低于9月龄。     

基于Gibbs抽样的贝叶斯方法估计大菱鲆生长和耐高温性状的遗传参数

为了开展大菱鲆耐高温选育工作,对其进行耐高温性状及其相关生长性状的遗传评估是非常必要的。以来源于英国、法国、丹麦和挪威4个国家的不同群体构建大菱鲆选育家系,利用F₁的20个和F₂的22个耐高温选育家系进行耐高温实验,统计耐高温评估指标（UTT）和相应的实验鱼体重（每个家系选取40-50尾实验鱼）。基于Gibbs抽样的贝叶斯方法,采用包含母性效应和不包含母性效应的两种动物模型,对大菱鲆耐高温（UTT）和生长性状的遗传力以及这两个性状间的遗传相关和表型相关进行分析。结果表明,基于不包含母性效应的动物模型估计的体重和耐高温性状的遗传力以及这两个性状之间的表型相关和遗传相关分别为0.239±0.141,0.111±0.080,0.075±0.026和-0.019±0.011。基于包含母性效应的动物模型估计的这4个值分别为0.203±0.115,0.055±0.026,0.047±0.034和-0.024±0.028,体重和耐高温性状的母性效应分别为0.050±0.017和0.013±0.004。母性效应对这两个性状的遗传评估有一定的影响。本文的研究结论为制订合理的大菱鲆耐高温育种规划提供了理论依据。     

大菱鲆(Scophrhalmus maximus)不同生长阶段体重的遗传参数和育种值估计

采用非求导约束最大似然法(DFREML)进行了大菱鲆不同生长阶段体重的遗传参数和育种值研究,每一生长阶段分别对4种不同动物模型估计遗传参数的差异进了比较.不同模型中对全同胞家系效应和日龄协变量作了不同的考虑:模型A,不考虑全同胞家系效应和日龄协变量:模型AD,仅考虑日龄协变量;模型AE仅考虑全同胞家系效应;模型AFD,同时考虑全同胞家系效应和日龄协变量.结果表明,6月龄利用模型AF,3月龄、9月龄、12月龄、15月龄利用模型AFD对遗传参数和育种值进行估计较为适合.利用育种值选择和表型值选择两种方法分别进行了家系选择和个体选择的效率比较,结果表明,在每一生长阶段依据育种值选择的效率均高于表型值选择的效率.利用不同生长阶段的家系育种值以及亲本育种值分别进行了家系选择比较和亲本选择比较,结果表明,在不同生长阶段,按家系、父本和母本的育种值分别排序,前50%的相同率和育种值的相关系数均为9-12月龄较6-9月龄的提高幅度比其它相邻阶段显著增加,推测家系提前筛选的时间以及父本和母本选择的时期均不低于9月龄.     

利用限制性最大似然方法和贝叶斯方法估计大菱鲆生长性状的遗传参数。

Bayesian and restricted maximum likelihood(REML) approaches were used to estimate the genetic parameters in a cultured turbot Scophthalmus maximus stock. The data set consisted of harvest body weight from 2 462progenies(17 months old) from 28 families that were produced through artificial insemination using 39 parent fish. An animal model was applied to partition each weight value into a fixed effect, an additive genetic effect, and a residual effect. The average body weight of each family, which was measured at 110 days post-hatching, was considered as a covariate. For Bayesian analysis, heritability and breeding values were estimated using both the posterior mean and mode from the joint posterior conditional distribution. The results revealed that for additive genetic variance, the posterior mean estimate( δ_a~2=9 320) was highest but with the smallest residual variance,REML estimates( δ_a~2=8 088) came second and the posterior mode estimate( δ_a~2=7 849) was lowest. The corresponding three heritability estimates followed the same trend as additive genetic variance and they were all high. The Pearson correlations between each pair of the three estimates of breeding values were all high,particularly that between the posterior mean and REML estimates(0.996 9). These results reveal that the differences between Bayesian and REML methods in terms of estimation of heritability and breeding values were small. This study provides another feasible method of genetic parameter estimation in selective breeding programs of turbot.     

凡纳滨对虾(Litopenaeus vannamei)体重、存活性状的遗传参数和基因型与环境互作效应

利用7个凡纳滨对虾(Litopenaeus vannamei)引进群体,通过双列杂交和巢式交配设计构建家系,建立育种基础群体,估计体重、存活性状的遗传参数和基因型与环境互作效应(genotype by environment interactions,G×E)。结果表明,凡纳滨对虾基础群体体重和存活性状的遗传力估计值范围分别在(0.19±0.09)—(0.43±0.09),(0.27±0.04)—(0.45±0.06),均属于中高遗传力水平,并且统计检验显著(P<0.05)。Z-score检验表明,体重和存活性状遗传力估计值在河北黄骅(HBHH)和青岛鳌山(QBAS)两个测试场间差异均不显著。体重和存活性状的表型和遗传相关系数分别为0.007和0.008,表现为低度线性负相关。对于体重和存活性状,HBHH和QBAS场间的遗传相关分别为0.83±0.04和0.40±0.11。体重性状的G×E效应不显著(K<0.5),但存活性状存在显著的G×E效应(K>0.5)。上述结果显示,凡纳滨对虾基础群体体重和存活性状的遗传变异丰富,多代选择可获得较大的遗传进展。     

大菱鲆体重性状遗传参数及选育遗传进展研究

本研究估计了大菱鲆收获体重性状的遗传参数和选育遗传进展。数据共包括3个世代（G0,G1,G2）的508个全同胞家系10952尾个体。G0,G1,G2的体重估计遗传力分别为0.11±0.08,0.18±0.09,0.17±0.07;世代间估计遗传力为0.19±0.04。每一世代母本和共同环境效应分别为0.10±0.04,0.14±0.04,0.13±0.03;世代间为0.12±0.01。G0和G1世代选择差分别为,18.24g和21.19g。对应的G1和G2世代的遗传进展为22.06g,11.93g;百分比表示分别为6.36%,3.52%。连续两代选择之后总遗传进展为10.10%。以上结果说明针对大菱鲆体重性状的选育项目是成功的。     

利用父母本微卫星标记估计大菱鲆(Scophthalmus maximus L.)幼鱼生长性状的遗传参数

The estimation of genetic parameters has played an important role in animal selective breeding for growth traits.Recently studies show that molecular markers can be incorporated into genetic evaluations. In order to improve the performance of an incomplete pedigree(i.e, only parents are known) in the genetic evaluations, 12 microsatellite markers have been applied in the estimation of the genetic parameters for body weight in a farmed population(n=1 890) of juvenile turbot(Scophthalmus maximus L.). A new relatedness called parental molecular relatedness(PMR) is estimated based on results of genotyping of 48 parents(31 males, 17 females) with microsatellites markers. The feasibility of PMR in estimation of genetic parameters is verified by comparison with pedigree related(PR) which is obtained from a complete pedigree. The results demonstrate that a high correlation(0.872) between them is found. Heritabilities are estimated using the PMR(0.52±0.13) and PR(0.55±0.22) with the same animal model. A cross-validation shows that the predictive abilities of models using the PMR and the PR are identical(0.81). From that, a conclusion can be made that PMR and PR predicted genetic values equally well in a population of juvenile turbot. Therefore PMR can be applied as an alternative of the PR when only parents are known. However, for a better performance, more markers and more families should be included in a further study.     

大菱鲆南方移养技术研究

利用秋末至次年夏初福建省海区自然水温一般处于大菱鲆(Scophthalmusmaximus)生长最适水温范围这一条件,采用陆上工厂化养殖和海上网箱养殖二种方式,试验其养殖效果。利用海上网箱养殖方式,可以在秋末夏初自然水温处于大菱鲆最适生长范围期间,将大菱鲆鱼苗饲养至平均体质量500g/尾的商品规格。从2003年11月26日至2004年4月2日,鱼苗从平均全长11.3cm、平均体质量113.6g生长至平均全长27.1cm、平均体质量500.4g,成活率86.7%。而同一阶段,陆上水泥池的水温一般要比自然海区低1～2℃,生长速度也较慢。另外,大菱鲆对高水温有相当的耐受能力,在平均水温达27.0℃、最低25.2℃、最高达29.2℃的6月份,成活率仍可达85.9%。结果表明,在南方开展大菱鲆阶段性养殖在技术上是可行的。     

Potassium channel in peripheral blood lymphocytes of turbot (Scophthalmus maximus)

In order to provide pertinent evidence of ion channel with immune response in the fish,whole cell patch-clamp technique was employed for potassium ion channel study in turbot(Scophthalmus maximus) . Lymphocytes were isolated by Percoll density gradient centrifugation from peripheral blood samples,and electrophysiological characters of the channel were analyzed. In the recorded cells,activated voltage of the channels was-42.5 ± 3.7 mV and the average peak current was 313.12 ± 28.2 pA. The channel was identified as voltage dependent,the current was outward and it could be inhibited by 10 mmol/dm 3 TEA or 5 mmol/dm 3 4-AP,a specific potassium channel inhibitor,identifying the existence of potassium channel in peripheral lymphocytes of the turbot.     

大菱鲆三倍体人工诱导条件优化及规模化诱导

大菱鲆(Scophthalmus maximus)是我国重要的海水养殖鱼种,三倍体诱导对其种质改良、产业提升和生态安全具有重要的价值。目前有关大菱鲆三倍体的人工诱导虽已有报道,但对其诱导条件缺乏细致的研究。本文采用冷休克法抑制第二极体排放,通过对诱导处理起始时刻、温度和持续时间3个主要因素的单因子实验,筛选其最佳诱导条件。结果显示,在受精和孵化水温为15.0±0.5℃条件下,受精后6 min,用–2～–1℃处理25 min可获得较好的诱导效果,流式细胞仪检测其诱导率可达100%。随后在最适条件下进行了规模化诱导,获得鱼苗200万尾以上,其诱导率高于98%。跟踪观察发现,三倍体诱导组胚胎的形态及孵化时间与二倍体对照组基本一致。本研究结果可为大菱鲆三倍体的产业化应用提供基础。     

大菱鲆幼鱼蛋白质的生态营养需要量研究

采用单因素随机区组设计,选择平均体质量34.5 g±5.5 g的大菱鲆(Scophthalmus maximus L.)幼鱼225尾,平均分为5组(A～E),每组3重复。分别喂以蛋白质水平为450,48%,50%,52%和54%的5种膨化颗粒饲料,探寻饲料蛋白质水平对大菱鲆幼鱼生长性能和水生态因子的影响,试验期88d。结果表明:不同蛋白质水平膨化饲料对大菱鲆幼鱼的生长性能和饲料利用率均产生了显著影响(P<0.05),净增质量、质量增长率、特定生长率随饲料蛋白水平的提高而增加,饲料系数随蛋白水平增加而降低;水生态因子中除pH外, 对其它指标都有显著影响(P<0.05),化学耗氧量(COD)、氨氮(NH3-N)、亚硝氮(NO2—N)、磷酸盐(PO4-P)的浓度都随饲料蛋白水平的提高而增加。其中,C组质量增长率比A,B组显著提高21.6%和14.6%(P<0.05),而比D,E组低1.6%和5.1%;C组饲料系数比A,B 组低0.22和0.16(P<0.05),而仅比D,E组高0.02和0.03;C组NH3—N比A,B组提高13.0%和4.0%,而比D,E组降低达23.1%和48.1%(P<0.05)。本试验从幼鱼生长性能和水生态因子两方面表明,大菱鲆幼鱼膨化饲料中蛋白质的生态营养需要量为50%。     

Morphological and histological changes in the brains of turbot (Scophthalmus maximus) with gonadal development

The brain plays a critical role in controlling reproduction through the hypothalamus-pituitary-gonadal (HPG) axis in vertebrates. Turbot (Scophthalmus maximus) has become an economically important marine fish in Europe and North China. Previous research investigating turbot reproduction has focused on the role of the HPG axis in regulating egg and sperm production. However, the morphology and histology of the organs in the HPG axis have not been studied. In this study, we investigated the morphology and histology of brains in female and male turbot at different stages of gonadal development. The results showed that the brains of both female and male turbot were composed of seven parts that are typical of advanced teleosts: the telencephalon, diencephalon, cerebellum, hypothalamus, pituitary gland, myelencephalon, and olfactory bulbs. The telencephalon was well-developed and contained five distinct lobes, with the contiguous diencephalon at the caudal portion. The torus longitudinales and rostral torus semicircularis of the mesencephalon flattened along the dorsal surface, and the rostral corpus cerebellum was located in the dorsal portion. The actual total brain volume in mature males was significantly greater (p<0.05) than that of females with gonadal development. Notably, the pituitary volume in male turbot significantly increased (p<0.05) from immature to mature stage, but this difference did not occur in females. The data together illustrate a distinct sex difference in the turbot brain during gonadal development, providing insight into their HPG axes.     

中国对虾(Fenneropenaeus chinensis)耐低温和生长性状的遗传参数估计

The inability of Fenneropenaeus chinensis to tolerate low temperatures is of major economic concern in temperate climates,as it reduces their growing season and leads to over-winter mortality.In this study,the heritability of body weight under low grow-out temperature and cold tolerance in F.chinensis were first investigated and estimated using 88 ful-sib families,which might provide crucial information in Chinese fleshy prawn breeding programs.The heritability for body weight under suitable and low temperature of F.chinensis were both moderate(0.158 0±0.307 5 and 0.132 0±0.026 9 respectively);the large coefficient of variation(approximately 21%) and moderate estimate of heritability for body weight indicated substantial potential for selective breeding.The heritability estimate for cold tolerance was low(0.019 2±0.023 5),and showed no significant differences from zero(P0.05).A weak genetic correlation between cold tolerance and body weight was also estimated in the present study,also showing no significant differences from zero(P0.05).Thus,more research needs to be conducted on the more accurate heritability estimate of cold tolerance and genetic correlations between traits in F.chinensis to further improve the achievement of breeding goals.