长牡蛎成体生长性状的遗传参数估计

在长牡蛎(Crassostrea gigas)的选择育种工作中,于2009年和2010年分别获得24个和32个全同胞家系。根据长牡蛎360日龄的壳高、壳长、壳宽、总重、壳重、肉重和出肉率参数,利用ASREML软件的REML方法计算表型变量的方差组分,估算了长牡蛎成体阶段生长性状的遗传参数。结果表明,不同年份长牡蛎家系的生长存在显著差异,2009年家系的壳高、肉重和出肉率显著低于2010年家系(P<0.05),2009年家系的总重则显著高于2010家系(P<0.05)。除出肉率外,2009年和2010年家系的壳高与其他生长性状均存在显著的正相关性(P<0.05)。壳高和总重具有较高的遗传力,分别为0.35±0.15和0.27±0.13。长牡蛎成体阶段各生长性状间的遗传相关和表型相关均为正相关,但相关性的大小不同。本研究估测的长牡蛎成体阶段生长性状的遗传参数,可以为合理制定长牡蛎的育种方案和选择反应预测提供参考依据。     

长牡蛎生长性状遗传力、遗传相关和表型相关分析

为了查清乳山(RS)和崆峒岛(KTD)海域长牡蛎生长性状各指标的遗传力、遗传相关和表型相关,本实验通过部分因子交配设计和人工授精的方法建立家系,并在乳山和崆峒岛海域进行养殖。用混合线性模型分别计算RS和KTD海域188日龄、338日龄和474日龄长牡蛎生长性状各指标的遗传参数。结果发现:不同日龄长牡蛎生长性状各指标,在乳山海域的遗传力是0.28~0.55,为中高遗传力,在崆峒岛海域的遗传力是0.34~0.63,为高遗传力;与乳山海域相比,崆峒岛海域各指标的遗传力偏高。运用亲本模型,将日龄和地点作为固定效应,计算得到壳高、壳长、壳宽和湿重的遗传力分别为0.25±0.08、0.29±0.09、0.14±0.05和0.26±0.09。不同海域、不同日龄的遗传相关和表型相关结果各不相同,但各指标间均呈现正相关;总体来讲,性状间的遗传相关大于表型相关。实验结果有助于掌握山东半岛南北两侧长牡蛎生长性状的数量遗传学参数,为制定长牡蛎在该海域的选育技术路线提供数据支持。     

长牡蛎壳金性状遗传参数评估及与生长性状的关联分析

采用家系选育与群体选育相结合的方法,以壳金性状和生长性状为主要选育指标,经过连续4代的选育获得了长牡蛎第4代壳金选育品系(F4)。本实验以F4代为亲本,采用巢式设计方法和人工授精技术,成功构建了25个长牡蛎壳金全同胞家系,分别测定了每个家系生长到9月龄时30个个体壳金性状颜色参数和生长性状,分析了2类性状的表型变异,并对壳金性状的遗传参数及与生长性状的相关性进行了分析。结果显示,壳金性状颜色参数L*、a*、b*、ΔE的遗传力分别为0.13±0.09、0.69±0.19、0.30±0.13、0.38±0.15;L*、a*、b*和ΔE之间的遗传相关和表型相关范围分别为–0.25~0.37、–0.1 9~0.8 0;颜色参数与各生长性状的遗传相关和表型相关均较低,分别为–0.04~0.26、–0.10~0.13。本研究表明长牡蛎壳金性状颜色参数的遗传力多为中高等水平,对其颜色继续进行选择改良,预期能达到良好的效果。此外,壳金性状与生长性状的相关性较低,不能利用二者之间的关系进行相互选择,只能将壳金性状和生长性状均作为目标性状进行协同选择,以实现同步改良2个性状的目的。     

长牡蛎壳橙性状遗传参数评估及与生长性状的关联性

长牡蛎壳橙快速生长品系是结合群体选育与种内群体间杂交方法,以壳色性状和生长性状为选育指标,经过连续3代选育获得的新品系。本研究以第1代长牡蛎壳橙快速生长品系(G₁)为亲本,采用巢式设计建立了48个混养家系,共获得863个个体。利用微卫星标记对混养家系进行了系谱分析,并基于REML法评估了长牡蛎壳橙快速生长品系壳色性状的遗传参数及与生长性状的相关性。结果显示,863个个体中,有851个个体被准确鉴定其所属家系;长牡蛎壳橙快速生长品系壳色性状颜色参数指标a^*(红绿轴色品指数)、b^*(黄蓝轴色品指数)和ΔE (色差)等均具中高等遗传力,大小依次为0.47±0.23、0.42±0.21和0.56±0.29。4个颜色参数指标间的遗传相关和表型相关范围分别为-0.79~0.86和-0.45~0.48。壳色性状与各生长性状的遗传相关和表型相关较低,分别为-0.33~0.17和-0.04~0.11。研究表明,在长牡蛎壳橙快速生长品系育种过程中,对壳色性状进行选育可以得到预期的改良效果。此外,壳橙性状与生长性状应分别作为目标性状进行协同选择,以实现同时改良两个性状的目的。本研究可为长牡蛎壳橙快速生长品系选育提供基础资料。     

壳白长牡蛎品系生长和壳色性状遗传参数估计

以经过连续4代家系选育获得的壳白长牡蛎(Crassostrea gigas)选育系为亲本,通过巢氏平衡设计建立了30个全同胞家系混合养殖,采用微卫星多重PCR技术进行家系鉴定,基于REML法估算24月龄壳白长牡蛎的生长性状和壳色性状的遗传参数。结果表明,壳白长牡蛎品系壳高、壳长、总重、壳重、L~*(明度)、a~*(红绿轴色品指数)和b~*(黄蓝轴色品指数)的遗传力为中高等水平,依次为0.35±0.13、0.18±0.09、0.20±0.09、0.16±0.08、0.16±0.08、0.27±0.11和0.19±0.08,壳宽、肉重、出肉率、壳型指数A和壳型指数B的遗传力为低等水平,依次是0.07±0.02、0.11±0.06、0.02±0.03、0.08±0.06和0.11±0.06。壳高、壳长、壳宽、总重、壳重和肉重之间的遗传相关和表型相关均为正相关,其中,壳高、壳宽和总重与其他生长性状的相关性较高,分别为0.40±0.65~0.90±0.14、0.39±0.55~0.97±0.24和0.50±0.66~0.99±0.02。壳型指数A和壳型指数B与壳高均为较高的负相关,分别为–0.94±0.16和–0.77±0.19,表明仅以壳高性状为选育目标时,可能不会对长牡蛎壳型改良产生作用。壳白长牡蛎壳色参数与生长性状之间的遗传相关范围为–0.09±0.42~0.91±0.74,不同性状间的遗传相关差异很大,其中L~*与生长参数遗传相关较高,为0.49±0.29~0.91±0.74,表明以壳高、壳长、总重和L~*任一个为选育目标时,其他生长性状都可以获得提高。壳色参数间L~*与a~*负的相关性最高,为–0.96±0.04,L~*与b~*和a~*与b~*相关性较低,分别为–0.08±0.36和0.21±0.31,表明以L~*为选育目标时,可间接降低a~*值。本研究为合理制定壳白长牡蛎新品系育种方案和选择反应预测提供了参考依据。     

大黄鱼低盐养殖生长性状的相关性和遗传力分析

通过对选育大黄鱼进行低盐养殖,采用通径系数分析了12月龄低盐养殖大黄鱼体高、体长和体质量的相关性并估算遗传力。试验结果表明,低盐养殖大黄鱼体长与体质量的相关关系(0.957)最大,体长对体质量的直接作用(0.658)最高;建立大黄鱼低盐养殖模式多元回归方程为m=-143.694+13.062L(r2=0.959),经显著性检验,体长对体质量的偏回归系数及回归常数均达到了极其显著水平(P0.01);分析低盐养殖大黄鱼体高、体长和体质量的现实遗传力分别为0.623、0.681和0.363均明显高于自然海水养殖大黄鱼的体高(0.178)、体长(0.548)和体质量(0.110)。低盐环境养殖的大黄鱼选育子代可以更好的继承亲本性状,应进行大黄鱼抗低盐育种。     

长牡蛎壳黑和壳白选育群体生长性状的选择效应

为了培育壳色性状优良且生长性状良好的长牡蛎(Crassostrea gigas)新品系,本研究以5个壳黑第四代家系和5个壳白第四代家系的成贝为基础群体,利用截头法对壳高进行选择,构建了壳黑和壳白快速生长系第一代群体,分析了两个选育群体的壳高和活体体重的选择反应、遗传获得和现实遗传力等遗传参数。结果表明,在长牡蛎收获的490日龄,壳黑群体和壳白群体选择组壳高较对照组壳高分别提高(9.83?1.68)%和(9.97?1.87)%,体重分别提高(10.16?3.64)%和(11.36?1.96)%。两选育群体壳高的平均现实遗传力分别为(0.353?0.09)和(0.405?0.111),体重的平均现实遗传力为(0.192?0.080)和(0.244?0.123)。本研究表明壳黑群体和壳白群体具有较大的遗传方差,在对壳高生长速度直接选择的同时实现了对活体体重的间接选育,可继续通过群体选育提高生长速度。本研究结果可以为培育出壳色美观、生长性状良好的长牡蛎优良品种提供科学依据。     

壳紫长牡蛎家系生长存活比较及生长性状的遗传参数评估

为了培育壳色和生长性状优良的壳紫长牡蛎(Crassostreagigas)新品系,2021年通过家系选育的方式,以壳色性状为主要选育指标,建立了第1代壳紫长牡蛎选育群体。本研究以壳紫F1为亲本,采用平衡巢式设计建立了36个全同胞家系,并以野生长牡蛎为亲本建立对照组,比较分析了各家系在生长和存活方面的性能表现;同时利用多性状动物模型对壳紫家系幼虫和稚贝期的生长性状遗传参数进行了评估。结果显示,不同生长阶段壳紫长牡蛎家系的存活率和壳高均值均高于对照组,幼虫期分别提高了1.49%～10.18%和3.75%～15.94%,稚贝期分别提高了4.05%～16.94%和15.95%～18.25%。不同壳紫家系的生长和存活情况也存在差异,没有发现在存活率和生长性状方面同时具有优势的家系。壳紫长牡蛎幼虫期壳高和壳长的狭义遗传力范围分别为0.43～0.84和0.49～0.80,稚贝期壳高和壳长的遗传力分别为0.15～0.33和0.18～0.37,均属于中高等遗传力。不同生长阶段壳紫长牡蛎家系壳高和壳长的遗传相关与表型相关均为正相关,幼虫期的相关系数分别为0.67～0.97和0.17～0.51,稚贝期为0....     

长牡蛎‘海大1号’生长性状的遗传参数评估

分别以长牡蛎(Crassostrea gigas)‘海大1号’第8代和第9代选育群体中的个体为亲本,采用巢式设计的交配方法,于2016年和2017年分别获得41个和38个全同胞家系。根据各家系长牡蛎330日龄的壳高、壳长、壳宽和体重等表型参数,通过建立多性状动物模型,利用ASReml软件中的限制性极大似然法估算各表型变量的方差组分,对‘海大1号’连续两代选育群体生长性状的遗传参数进行评估。结果表明,两个选育世代的‘海大1号’生长性状均具有较高的变异水平,变异系数为20.74%~55.14%,各生长性状仍具有遗传改良潜力。‘海大1号’各生长性状间的表型相关均为正相关,相关系数大小存在差异。3个壳型性状与体重的遗传相关均为正相关,且处于较高水平(0.40~0.66)。除壳宽性状的遗传力较低外,壳高、壳长与体重的遗传力在0.16~0.37,均属中高等遗传力水平,表明‘海大1号’经过多代选育后,生长性状仍具有较大的加性遗传效应,可根据个体表型值大小,继续通过群体选育获得遗传进展。研究结果为长牡蛎‘海大1号’制种方案的制订和保种工作提供了参考依据。     

长牡蛎糖原磷酸化酶基因SNPs与生长性状和糖原含量的相关性分析

为研究糖原磷酸化酶基因多态性与长牡蛎(Crassostrea gigas)生长和糖原含量的相关性,本研究对长牡蛎糖原磷酸化酶基因(Cg-GPH)编码区单核苷酸多态性(SNPs)与来自5个家系322个长牡蛎个体的生长性状(包括壳高、壳长、壳宽、总体质量以及软体部质量)和糖原含量进行了关联分析.结果表明,在1940 bp的长牡蛎糖原磷酸化酶基因中共检测到82个SNPs位点,其中63个SNPs位点位于外显子区域,1个SNPs位点位于5′-UTR区,18个SNPs位点位于3′-UTR区,编码区SNPs平均密度为1/25 bp;5个SNPs位点与生长性状存在显著相关(P<0.05),未检测到与糖原含量相关SNPs.根据以上5个SNPs位点共构建得到6个SNP单倍型,其中,Cg-GPH基因的H6(CTGAT)单倍型在总体质量性状方面均显著高于其他5种单倍型(P<0.05),表明H6单倍型可能是对长牡蛎体质量增加最有利的单倍型.研究结果为今后长牡蛎生长性状的遗传改良提供了基础资料.     

Estimates of heritabilities and genetic correlations for growth and gonad traits in the sea urchin Strongylocentrotus intermedius

The present study is the first estimate for the sea urchin, Strongylocentrotus intermedius, of genetic parameters for growth and gonad traits during the entire reproductive period. 2165–5764 sea urchins were sampled from 74 to 120 families at six different growth stages. Six hundred individuals were sampled from 20 randomly chosen families at harvest. Coefficients of variation for most growth and gonad traits were high (18.08–78.66%) suggesting a good variation foundation for breeding. Point estimate for heritabilities based on the sire components of variance were moderate to high for test height (0.24–0.39), test diameter (0.21–0.48) and body weight (0.16–0.49). Heritabilities of gonad wet weight, gonad index and gonad moisture at harvest were 0.17, 0.41 and 0.50 respectively (moderate or high). Gonad colour parameters, L^* (lightness) and a^* (redness) have a heritability of 0, while b^* (yellowness) and colour difference ΔE₁ and ΔE₂ have very similar heritabilities of 0.2, 0.18 and 0.21 respectively. Heritabilities of β‐carotene concentration and content were 0.89 and 0.44 respectively. The genetic correlations between the two measured traits ranged from ?0.984 to 0.999. Gonad wet weight, L^*, b^*, β‐carotene concentration and β‐carotene content had significant positive genetic correlations with all the growth traits. However, gonad index, gonad moisture and colour differences ΔE₁ and ΔE₂ had significant negative genetic correlations with growth traits. The present study indicates that growth, gonad yield and most gonad quality traits could be improved by selection with moderate to high potential. Indirect selection should be applied on gonad traits using growth traits as secondary traits. The present study provides important theoretical guidance for future selective breeding programmes for S. intermedius.     

A preliminary study on growth of Crassostrea gigas larvae and spat in relation to dietary protein

Diets of Chaetoceros calcitrans (Paulsen) Takano and Tetraselmis suecica (Kylin) Butch containing high or low levels of protein were fed to Crassostrea gigas Thunberg larvae and spat. The 4-day increment in D-larvae shell length was not related to differences in the ash-free dry weight or protein content of the diets at cell concentrations of 75–125 Chaetoceros μl⁻¹. At concentrations of 2–100 Chaetoceros μl⁻¹ the largest growth increment was found when 0.267 μg ash-free dry weight larva⁻¹ d⁻¹ (equivalent to 3.35 Joules · 10⁻³ larva⁻¹ d⁻¹) was filtered at a temperature of 28.1°C.Percentage settlement of C. gigas increased as protein in Chaetoceros, fed at 75–125 cells μl⁻¹ (P < 0.001), and in Tetraselmis, fed at 5–15 cells μl⁻¹ (P < 0.05), increased. Growth of spat during the 14 days immediately after settlement was better on a low-protein than a high-protein Tetraselmis diet (P < 0.001) but differences between Chaetoceros diets were not significant.     

A herpes-like virus infecting Crassostrea gigas and Ruditapes philippinarum larvae in France

Concomitant sporadic high mortalities were reported in June 1997 among batches of larval Pacific oyster, Crassostrea gigas, and Manila clam, Ruditapes philippinarum , in a French commercial hatchery. Histological observation showed the presence of cellular abnormalities in affected animals. Electron transmission microscopy revealed the presence of herpes-like virus particles in infected larvae of both bivalve species. Viruses observed in C. gigas and R. philippinarum are closely related with respect to ultrastructure and morphogenesis. They were detected simultaneously in both bivalve species larvae indicating possible interspecific transmission. Moreover, PCR analysis using oyster herpes-like virus specific primers allowed amplification of fragments of expected sizes for both bivalve species and demonstrated the presence of viral DNA. The PCR products obtained for both bivalve species and digested by restriction enzymes displayed the same patterns. These data suggest that the same herpes-like virus may infect larval oysters and clams.     

Genetic parameters of growth and survival in the Pacific oyster Crassostrea gigas

The Pacific oyster Crassostrea gigas is a representative bivalve mollusc that is widely cultured in the world and is the largest molluscan group cultured in China. In order to assess the feasibility of improving survival of C. gigas through genetic selection, the heritability and genetic correlations for growth and survival traits between different life stages were examined. Genetic parameters were estimated based on intraclass correlations of 49 full‐sib families (29 half‐sib families) in larvae (4 and 20 days after fertilization) and spat (140 days after fertilization) stages. The heritability for growth traits in larvae and spat was 0.30–0.86 and 0.53–0.59, respectively, and varied with ages. The heritability of survival was low in larvae (0.13 ± 0.05 and 0.17 ± 0.04, respectively for 4 and 20 days after fertilization) but medium (0.39 ± 0.07) in spat, suggesting that selection for increasing spat survival was feasible. The genetic correlation between growth traits within age was medium to high and positive (ranging from 0.47 to 0.96, respectively, between shell length (SL) and shell height (SH) at 20 days and between SL and SH at 140 days after fertilization), suggesting that selection to improve single growth trait will cause positive response in another growth traits in C. gigas. The genetic correlations between survival and growth traits at 140 days were low but positive (ranging from 0.23 to 0.27, respectively, between survival and SH and between survival and SL at 140 days after fertilization), suggesting that selection for survival may not have a negative response in growth. Overall, this study suggests that survival traits should be taken as improving target of next selection breeding programme in C. gigas.     

Identification and counting of Pacific oyster Crassostrea gigas larvae by object detection using deep learning

Natural seedling collection is widely used in the culture of various bivalve species. For successful natural seedling collection, collectors must be installed when larvae appear in the water column at a stage immediately before attachment. Aquaculture farmers generally identify target larvae by morphological features through microscopic examination in a time- and labor-expensive exercise, which also requires a level of expertise to ensure accurate larval identification. We develop a deep-learning-based object-detection technique that ultimately might reduce the time and effort required to accurately identify and count Pacific oyster larvae, render their identification more consistent, and negate the need for expertise. Images of plankton net samples collected in Matsushima and Sendai bays, Japan, were taken using a new photographic device with a CMOS image sensor. Images of oyster larvae identified by an expert were used to create a library of labeled images to train a deep-learning model, which proved to be 82.4% accurate in precision, 90.8% in recall, and 86.4% in F-measure. A further method for estimating larval shell height from the rectangular shape of oyster larval images is also developed. The standardized mean difference in shell height between measurements and estimates is 3.3%. This deep-learning model has the potential to significantly reduce the time and effort required to identify oyster larvae in plankton samples, and thereby costs of this exercise.     

The lipid content, spatfall and subsequent growth of early and late settling hatchery-reared Pacific oyster, Crassostrea gigas Thunberg, larvae

Six experimental batches of Pacific oyster larvae, Crassostrea gigas Thunberg, were reared on a standard diet in the hatchery. After 8-12 days from fertilization, the larvae were separated into two to three size groups. These groups of larvae were then reared separately through to settlement. A sample was taken from each group when the larvae had reached the stage at which they were ready to settle for estimation of number, size and weight, and analysis of total lipid. All the spat that settled from each group were removed daily during the settlement period of 10-14 days. Selected samples of 1000 or more spat, collected from a single (day) settlement, were reared in standard hatchery upwelling systems for a further 30 days. Spatfall, as a percentage of the number of larvae in the group available to settle, was similar for all three groups of larvae, although it varied between experiments, and was positively correlated with the amount of lipid in the eyed larvae. The average spatfall, for all groups, was 44%. The dry and organic weights of spat that settled from the group of larvae that grew fastest were significantly greater than that for spat from the group with the slowest growth rate. Lipid content of the spat in the three groups was similar (9.3-12.4%). The spat that settled from the group of larvae that grew fastest also tended to be biggest after rearing in the hatchery for a further 30 days, but this result was not statistically significant. Spat from within the same group of larvae also grew to a similar size in this time, irrespective of whether they were collected during the first 3 days of settlement, or after a further 5 days. In practical terms, the results of these experiments show that it is cost-effective for hatchery operators to maintain batches of larvae for as long as settlement continues, to maximize the output of spat numbers without any danger of wasting resources by producing inferior quality or slower growing animals.     

Use of a probiotic for the culture of larvae of the Pacific oyster (Crassostrea gigas Thunberg)

Additions of bacteria (strain CA2) as a food supplement to xenic larval cultures of the oyster Crassostrea gigas consistently enhanced growth of larvae during different seasons of the year. Bacterial enhancement of larval growth occurred when either Isochrysis galbana (ISO), I. aff. galbana (T-ISO) or Pseudoisochrysis paradoxa (VA-12) were used as algal foods. Additions of CA2 bacteria at 10⁵ cells ml⁻¹ to cultures of algal-fed larvae increased larval growth, the proportion of larvae that set to produce spat, and the subsequent size of spat. A lower proportion of slow-growing larvae in populations receiving additions of CA2 bacteria compared with populations of larvae fed only algae, suggests a bacterial nutritional contribution to larval growth. Manipulation of bacterial populations present in bivalve larval cultures is a potentially useful strategy for the enhancement of oyster production.     

关于太平洋牡蛎的养殖技术之二太平洋牡蛎工厂化育苗技术的研究

本文是对太平洋牡蛎工厂化育苗技术的总结,论述了太平洋牡朗工厂化育苗技术以及在水质、饵料、固着基的选用中应注意的事项,并就生产中遇到的问题进行讨论。一、材料太平洋牡蛎亲贝来源于福建省漳浦县竹屿虾池,壳长平均95cm,幼虫固着基为太平洋牡蛎壳中间打了孔,光滑面相对,用45丝聚乙烯穿成串,每串100片,4串为一组,青苗有效水体560m3,饵料池水体150m3,使用经二级沙滤沉淀过后的海水。二、方法1亲贝培育：于今年元月上旬购进个体大、生长正确、无病害亲贝放人虾池育肥促熟．加强虾池饵料生物培养,调节好水质。2人工授精孵化：从…