长江中游鳙群体的微卫星遗传多样性分析

为了解长江中游鳙(Aristichthys nobilis)群体的遗传特征,利用12对微卫星引物对长江中游石首、监利和长沙3个鳙群体的遗传多样性和遗传结构进行了分析。结果显示:12个微卫星位点中有8个为高度多态位点,4对为中度多态位点,群体的观察杂合度(Ho)为0.398～0.778,期望杂合度(He)为0.425～0.919,多态含量信息(PIC)为0.371～0.907,3个群体遗传多样性较高。95.60%的遗传变异来自群体内,4.40%来自群体间,群体间的遗传分化程度较低(F_(st)=0.044),石首和监利群体的遗传分化最小(F_(st)=0.002 53),遗传距离最近(d=0.031 9),监利和长沙群体的遗传分化指数和遗传距离均最大(F_(st)=0.023 69,d=0.076 6)。结果表明长江中游三个群体具有较高的遗传多样性,长江中游干流群体与长沙群体间的遗传分化较小。     

红鳍东方鲀亲本群体遗传多样性的微卫星分析

从日本进口的红鳍东方鲀Takifugu rubripes受精卵发育至性成熟的120尾亲鱼群体中,选择22个分布于每个连锁群的微卫星标记进行了遗传分析,以分析红鳍东方鲀亲本群体的遗传多样性,并筛选出有效鉴定群体遗传特征的特异性微卫星标记。结果显示:等位基因数(Na)和有效等位基因数(Ae)的范围分别介于4.000~13.000和1.834~7.706之间。观测杂合度(Ho)、期望杂合度(He)和多态信息含量(PIC)的范围分别为0.173~0.977、0.456~0.872和0.427~0.857。Hardy-Weinberg遗传偏离指数(d)介于-0.746~0.344。群体内个体间的遗传距离在0.51~0.86之间,依据遗传距离的远近将全部个体分成4个群体,每个群体23~38个体。各项遗传参数表明:该实验群体具有较为丰富的遗传多样性,不同个体之间拥有相对较远的亲缘关系,可以根据个体间的遗传距离制定育种计划,建立家系进行选育研究。实验所选的22个微卫星标记具有高度多态性,可作为分析红鳍东方鲀群体遗传多样性的候选标记。     

基于微卫星评估草鱼放流亲本对野生群体遗传多样性的影响

利用筛选的13对草鱼多态性微卫星标记,开展了2011至2015年长江中游草鱼亲本增殖放流对野生群体遗传多样性的影响评估。通过对各位点的遗传多样性分析,13个微卫星位点的多态信息含量为0.8622(0.657~0.950),基因多样度为0.8555(0.675~0.936)。15个群体的有效等位基因数为7.4503~10.1536,等位基因丰度为11.483~15.204,说明15个草鱼群体的遗传多样性水平总体较高。遗传分化指数分析表明,群体间不存在显著遗传分化(FST5%)。通过贝叶斯聚类分析和主成分分析可将草鱼群体分为4个组群,根据分组结果以及来源划分分别对草鱼群体进行AMOVA分析,发现遗传变异大部分来自于群体内个体间,组间及组内群体间的分化水平较低(FCT5%,FSC5%),与FST分析结果一致。研究表明,当前草鱼亲本增殖放流模式对野生群体遗传结构影响不明显。     

安徽两水系黄颡鱼的微卫星遗传多样性分析

为了解安徽省内长江和淮河水系黄颡鱼(Pelteobagrus fulvidraco)遗传多样性和遗传结构,选用10个微卫星标记对9个自然群体共254尾黄颡鱼进行了遗传分析。共检测到等位基因数(N_a) 245个,平均有效等位基因数(N_e) 9.75个。各群体的平均N_a为5.20～14.80,平均N_e为2.64～8.93;平均观测杂合度(H_o)为0.496～0.671,平均期望杂合度(H_e)为0.557～0.818;平均多态信息含量(PIC)为0.500～0.790。AMOVA分析显示仅8.15%的遗传变异来自群体间,各群体间的遗传分化指数(F_(ST))为0.006～0.236。基于Nei's遗传距离的UPGMA系统树和利用Structure软件的群体遗传结构分析均显示,9个群体可被划分4或5个谱系,其中石台(秋浦河水系)、麻川河(青弋江支流)、阜南(淮河水系) 3个群体的个体遗传结构均比较独立,与其他群体亲缘关系较远;其他6个群体(长江水系的望江、无为、龙窝湖、泾县群体和淮河水系的凤台、瓦埠湖)的较为复杂,可能存在谱系间的混杂。结果表明,研究区域内黄颡鱼野生资源遗传多样性较高,地理群体间存在遗传分化且部分群体可能经历了瓶颈效应。     

鞍带石斑鱼繁育群体遗传多样性分析

鞍带石斑鱼作为最大型的石斑鱼,生长速度快,有明显的生长优势,在石斑鱼的产业发展中起到举足轻重的作用。为了解人工养殖和选育活动对鞍带石斑鱼遗传多样性的影响,本文采用微卫星分子标记技术,对广东、海南和福建三个省份共五个代表性采集点的鞍带石斑鱼繁育群体的遗传变异信息进行了研究。群体内遗传多样性分析显示,5个群体等位基因(Na)的平均数目为7.326(6.375-8.380),观测杂合度(Ho)平均值为0.711(0.625-0.775),期望杂合度(He)平均值为0.705(0.684-0.734),多态信息含量(PIC)平均值为0.659(0.633-0.693)。其中,来自福建厦门翔安区的鞍带石斑鱼繁育群体遗传多样性最高。分子方差分析(AMOVA)结果显示,5.36%的遗传变异来自群体间,95.45%来自所有个体间。群体间遗传分化指数(Fst)及遗传距离结果显示,GC和CP群体聚为一支,再与AT群体聚为一支,再与XA群体距为一支,HL群体为独立一支。通过系统进化树分析显示,鞍带石斑鱼繁育群体交叉在一起,没有形成明显的地理格局分布。总而言之,这三省五地的鞍带石斑鱼繁育群体遗传多样性较高,没有明显的驯化迹象。整体研究表明,鞍带石斑鱼繁育群体仍具有较高的遗传多样性,品种受亲本近交影响而出现衰退的可能性不高,人工繁育技术的不完善及养殖管理不规范可能是导致品种病害频发及养殖成活率低的原因。本研究为鞍带石斑鱼种质评价和人工选育提供理论依据。     

凡纳滨对虾亲本和子一代群体的线粒体DNA遗传特征研究

对凡纳滨对虾亲本和子一代进行线粒体控制区扩增,经测序共获得53个样本(亲虾15个,子一代38个)的线粒体D-loop区序列,长为530 bp,序列有24个变异位点,总变异为4.53%,1个插入和(或)缺失位点,共13种单倍型,13个单倍型T、C、A、G的平均含量分别为48.8%、10.6%、33.6%和7.0%,(A+T)%为82.4%,远大于(G+C)%的17.6%。亲本群体与子一代群体碱基含量相同,没有差异。凡纳滨对虾亲本15个个体有5个单倍型,单倍型多样性为0.695,核苷酸多样性为0.010 26,子一代单倍型多样性为0.772,核苷酸多样性为0.01038。凡纳滨对虾亲本群体与子一代群体的遗传距离为0.001,其中亲本群体内个体间的平均遗传距离为0.0145,子一代群体内平均遗传距离为0.0120。亲本和子一代间的遗传分化系数为-0.036 44,AMOVA分析显示,变异主要来自于群体内,亲本与子一代间无分化。     

凡纳滨对虾养殖亲本群体遗传多样性分析

运用微卫星标记技术,选用8对微卫星引物对厦门市5个凡纳滨对虾亲虾群体(ZA1、HN、ZA2、ZP、DS)进行遗传多样性分析。结果显示,8对微卫星引物在5个凡纳滨对虾亲虾群体中共检测到75个等位基因,各群体的平均等位基因数(Na)为3. 875～7. 000、平均有效等位基因数(Ne)为2. 632～3. 719、平均PIC值范围在0. 498～0. 624。平均观测杂合度(Ho)为0. 410～0. 562、平均期望杂合度(He)为0. 589～0. 687。各群体的平均近交系数(Fis)为0. 147～0. 305,说明各群体内近交程度较高,存在杂合子缺失现象。除ZP与DS群体外,其他群体在多个微卫星位点上均显著偏离平衡(P 0. 05),说明大部分群体存在杂合子缺失现象。遗传变异分析结果显示,各群体间的遗传分化指数(Fst)为0. 028～0. 199;根据Fst计算得到各群体间的Slatkin’s遗传距离在0. 029～0. 249之间。本研究结果表明,采自厦门市的5个凡纳滨对虾亲虾群体均存在不同程度的近交现象。本文通过对厦门市5个凡纳滨对虾亲虾群体进行遗传多样性分析,旨在明确厦门市凡纳滨对虾亲虾群体的遗传结构、种质资源状况及近交程度,为该地区凡纳滨对虾种质资源的提纯、保优、复壮及遗传选育提供背景资料和建议。     

津鲢与长江鲢遗传多样性分析

随机选取津鲢和长江鲢各36尾,用16个微卫星标记进行遗传多样性分析。结果显示:16个微卫星位点在2个群体中共检测到等位基因105个,基因型241种,每个位点等位基因数3～15个,平均6.6个,基因型4～37种,平均15.1种。2个鲢群体平均观察杂合度(Ho)分别为0.5393和0.5392,平均期望杂合度(He)分别为0.5887和0.5762,结果表明该2个鲢群体遗传多样性水平较高。2个鲢群体平均多态信息含量(PIC)分别为0.5602和0.54,固定系数(FIS)表明这2个鲢群体表现为杂合子缺乏(FIS0)。2个鲢群体之间的遗传距离为0.0566,平均遗传分化系数(Fst)值为0.021,说明仅有2.1%的遗传变异来源于群体间。     

驯食配合饲料的大口黑鲈3个选育世代的遗传多样性分析

为了检测驯食配合饲料的大口黑鲈(Micropterus salmoides)3个选育世代群体遗传多样性水平变化,利用微卫星标记技术对驯食配合饲料大口黑鲈选育基础群体(Sp0)和第二、三和四代选育群体(Sp2、Sp3和Sp4)共240尾样品进行检测。结果显示,18个微卫星位点共获得44个等位基因。Sp0、Sp2、Sp3和Sp4的平均观测杂合度(H_o)分别为0.4895、0.4802、0.4579和0.4206,平均期望杂合度(H_e)分别为0.4615、0.4454、0.4621和0.3916,平均多态信息含量(PIC)分别为0.3791、0.3659、0.3764和0.3257。4个群体间的配对比较群体间遗传分化指数(F_(st))值在0.01612～0.16162之间、遗传距离(D_a)在0.0249～0.1434之间。遗传变异来源(AMOVA)分析显示,只有8.38%的变异来自于群体间,其余遗传变异均来自于个体间。研究表明,经连续多代选育之后,易驯食配合饲料的快长大口黑鲈选育群体具有中度遗传多样性,具备选育潜力,可继续进行选育。     

用微卫星标记分析不同形态变异类型日本囊对虾的遗传多样性

选用9个多态性微卫星分子标记,分析我国近海浙江舟山(ZS)、福建厦门(XM)、广东惠来(HLQ及HLB)、海南陵水(LS)及广西北海(BH)日本囊对虾6个群体2种形态变异类型群体间的遗传变异,探讨了日本囊对虾的种质资源状况。结果显示,9个位点在6个日本囊对虾群体中均为高度多态(PIC>0.5),共检测出235个等位基因;6个群体平均等位基因数在13.2～17.7;PIC平均值在0.851 2～0.903 5;平均观测杂合度(Ho)在0.729 6～0.788 9,平均期望杂合度(He)在0.880 5～0.925 1;表明群体遗传多样性水平较高。Hardy-Weinberg平衡检测显示,6个群体普遍存在杂合子缺失现象。分子变异方差分析(AMOVA)结果表明,遗传变异6.94%来自群体间,93.06%来自群体内。由ZS、XM和HLQ群体组成的形态变异类型Ⅰ与由HLB、LS和BH群体组成的形态变异类型Ⅱ之间的Fst均大于0.05,发生了中等程度的遗传分化;相同形态变异类型各群体间的Fst均小于0.05,遗传分化不明显。日本囊对虾群体间的遗传距离(DA)为0.178 5～0.621 8;UPGMA聚类分析表明,聚类关系符合距离隔离模式,BH群体和LS群体遗传距离最小,亲缘关系最近,它们首先聚在一起,然后与HLB群体聚为一支;XM群体和HLQ群体先聚在一起,再与ZS群体聚为另一支。     

基于微卫星标记对长江江苏段鳙增殖放流效果评估

为评估长江江苏段鳙(Aristichthysnobilis)增殖放流效果,本研究基于微卫星标记的亲子鉴定技术,选用10对扩增效果稳定的微卫星荧光标记引物,结合毛细管电泳对江苏省内良种场563尾鳙亲鱼和长江江苏段687尾回捕鳙进行基因分型,并对位点多态性及亲子鉴定结果进行了分析。结果表明,各位点等位基因介于19～55之间,其观测杂合度为0.530～0.909(平均值为0.748),期望杂合度为0.818～0.929(平均值为0.882),多态性信息含量为0.797～0.924 (平均值为0.871); Cervus3.0模拟结果显示,当双亲未知且置信度为95%时, 10个微卫星位点的累积非亲权排除率为99.996%。亲子鉴定结果发现,所有回捕鳙中有42尾与亲本之间存在亲子关系,被确认来源于鳙增殖放流群体,并由此推算此次评估亲本的放流子代对长江江苏段野生群体的贡献率为6.11%。结果显示该研究进行的鳙亲子鉴定技术可为长江鳙增殖放流效果评估工作提供可靠的数据支撑,为长江渔业资源管理提供参考资料。     

人工雌核发育鲢近交F_2微卫星DNA变异分析

采用17对鲢微卫星引物,以野生鲢、养殖鲢、雄鲤作对照对人工雌核发育鲢近交F2及其亲本进行了微卫星分析。结果表明:人工雌核发育鲢近交F2、养殖鲢和野生鲢群体的平均等位基因数范围为2.1～4.0;平均观测杂合度范围为0.2762～0.9588;期望杂合度范围为0.2774～0.7360;遗传多样性指数范围为0.4500～1.2258,人工雌核鲢近交F2为0.4500,显著低于养殖鲢(1.0273)和野生鲢(1.2258),揭示人工雌核发育鲢近交F2遗传多样性水平较低,纯合度较高。从遗传距离来看,人工雌核发育鲢近交F2与对照群体之间的遗传距离都要大于野生鲢与养殖鲢群体之间遗传距离,表明人工雌核发育鲢近交F2发生了一定程度的遗传分化。     

Genetic variation in farmed populations of the gilthead sea bream Sparus aurata in Greece using microsatellite DNA markers

Genetic variation in seven reared stocks of gilthead sea bream Sparus aurata, originating from Greek commercial farms, was assessed using five polymorphic microsatellite markers and was compared with that of two natural populations from the Ionian and the Adriatic Seas. The total number of alleles per marker ranged from 11 to 19 alleles, and hatchery samples showed the same levels of observed heterozygosity with samples from the wild but substantially smaller allelic diversity and expected heterozygosity. The global genetic differentiation for the cultivated samples was significant as indicated by F_st analysis, which might indicate random genetic drift and inbreeding events operating in the hatcheries. On the contrary, no significant difference was found between the two wild populations. Population pairwise tests between farmed and wild stocks were also significant, with the exception of one hatchery sample, the Central Greece 1, which was not significantly different from the two wild samples perhaps due to its recent use in aquaculture from wild‐caught animals. The UPGMA tree topology grouped the wild samples together with the Central Greece 1 stock, and showed a clear division between wild and farmed sample sets for the six remaining hatchery samples. Knowledge of the genetic variation in S. aurata cultured populations compared with that in the wild ones is essential for setting up appropriate guidelines for the proper monitoring and management of the stocks either under traditional practices or for the implementation of selective breeding programmes.     

长江中下游鲢、鳙、草鱼、青鱼种群分化的同工酶分析

为查明长江中下游鲢、鳙、草鱼、青鱼有无不同种群，用聚丙烯酰胺凝胶电泳测定了长江中游天鹅洲故道、汉阳、瑞昌江段和下游安庆江段鲢、鳙、草鱼、青鱼各４个群体间的生化遗传变异。同种鱼各群体间的遗传变异未见有显著差异。遗传距离Ｄ值均小于０．００１。由此，初步认为长江中下游的鲢、鳙、草鱼、青鱼应各属一个没有显著遗传分化的种群，我们称之为“长江种群”。因而，在长江中下游选择一处优良保护场所就有可能达到就地保护长     

Increase of inbreeding by stocking on wild population assessed by using in dividual-based life history model

ABSTRACT:   The genetic impact of stocking on natural populations was assessed by using individual-based life history models. Models were constructed that included density-dependent mortality at the early life stage, natural mortality, fishing mortality, and the number of released fish. These variables were varied by using random numbers. The focus was on the genetic impact of the number of released fish, the number of parent fish producing seedlings that were released, the sex ratio of the parent fish, fishing mortality, and the methods to select the parents of the seedlings. When brood stock size in the hatchery was five males and five females, the coefficient of inbreeding was about 27-fold as high as that in the case of 50 males and 50 females at the 50th generation. The coefficient increased about fivefold at the 50th generation, when the sex ratio of the parents changed from 50 males and 50 females to 10 males and 90 females. When parents were taken from wild populations at random, extreme fishing mortality reduced genetic diversity.     

Allozyme variation of hatchery and river populations of rohu (Labeo rohita, Hamilton) in Bangladesh

The genetic variations of rohu (Labeo rohita, Hamilton) sampled from five hatchery populations (Arabpur, Brahmaputra, Comilla, Kishorganj and Natore) and three major river populations (the Halda, the Jamuna and the Padma) were analysed by allozyme electrophoresis. Ten enzymes encoded by 11 loci were screened, and six were polymorphic. Alleles at three loci (Est‐1^*, Gpi‐1^* and Gpi‐2^*) proved variable for hatchery and river populations, and the Mdh‐2^* locus exhibited heterozygous genotypes for river populations only. Polymorphic loci per population (27.3±5.3%), heterozygous loci per individual (15.5±1.2%) and relative gene diversity (0.27±0.08) in river populations were higher than those for hatchery populations (25.5±1.8%, 10.7±1.6% and 0.25±0.01 respectively). Also, the observed heterozygosity (Ho) and expected heterozygosity (He) (0.09±0.03 and 0.14±0.04 respectively) in river populations were higher than those in hatchery populations (0.08±0.01 and 0.11±0.01 respectively). The lower levels of genetic variability in hatchery populations suggested the occurrence of inbreeding and/or genetic drift. The pairwise population differentiation (F_ST) values showed a lower level of genetic differentiation between hatchery and river population pairs. The unweighted pair‐group method with arithmetic mean dendrogram of Nei's genetic distances showed a relationship between the genetic distance and geographic distance. The populations were clustered into three groups: the Padma in one group, the Halda in second group and the Jamuna, including five hatcheries, in the third group. Highly diversified rohu individuals were observed in the Padma and Halda Rivers, whereas less genetically variable individuals were found in the Jamuna River and five hatcheries. These findings can be useful for rohu hatchery propagation to enhance the sustainable aquaculture production.     

Recent advances in carp seed production and milt cryopreservation

The fish-seed production industry in India has recorded remarkable growth over the last three decades. The hypophysation technique was successfully introduced into India in 1957 and steady progress towards the refinement of the technique has been registered, which has revolutionized carp seed production in the Indian subcontinent. Advancement of carp maturity through brood stock management and multiple breeding has enabled spawn production well ahead of the monsoon and even beyond, ensuring seed availability throughout the year. The quality of seed is an important consideration for commercial aquaculturists. So, partial stock replenishment in carp hatcheries is practised to overcome the problem of inbreeding, which otherwise leads to poor growth of carps. Similarly, gametes of improved stock are cryopreserved and utilized for quality seed production as well as upgrading the brood stock of carps. The gamete cryopreservation protocol for carps is the focus of this review. An attempt has also been made to incorporate information on carp brood stock management, inducing agents, and seed production, including hatchery management.     

Genetic relationship between broodstocks of olive flounder, Paralichthys olivaceus (Temminck and Schlegel) using microsatellite markers

For the first generation of a selective breeding programme, it is important to minimize the possibility of inbreeding. This mostly occurs by mating between closely related individuals, while proper mating can provide an opportunity to establish the base families with wide genetic variation from which selection for subsequent generations can be more effective. Genotyping with microsatellite‐based DNA markers can help us determine the genetic distances between the base populations. The genetic markers further facilitate the identification of the correct parents of the offspring (parentage assignments) reared together with many other families after hatching. We established a genetic analysis system with microsatellite DNA markers and analysed the genetic distances of three farmed stocks and a group of fish collected from wild populations using eight microsatellite markers. The averaged heterozygosity of the farming stocks was 0.826 and that of the wild population was 0.868. The hatchery strains had an average of 8.6 alleles per marker, which was less than a wild population that carried an average of 14.3 alleles per marker. Significant Hardy–Weinberg disequilibrium (HWDE) was observed in two farming stocks (P<0.05). Despite relatively low inbreeding coefficiency of the hatchery populations, the frequency of a few alleles was highly represented over others. It suggests that the hatchery stocks to some extent have experienced inbreeding or they originated from closely related individuals. We will develop a selective program using the DNA markers and will widen the usage of the DNA‐based genetic analysis system to other fish species.     

Genetic differentiation of wild and hatchery Oujiang color common carp: potential application to the identification of escapees

The escape or release of cultured and domesticated organisms into the wild poses a threat to the genetic integrity of natural populations. Based on data from 17 microsatellite loci, the genetic differentiation between wild and hatchery Oujiang color common carp Cyprinus carpio var. color was investigated, and its potential application for identifying the escapees of hatchery strains was assessed using Bayesian genetic assignment. No significant differences were observed between pooled hatchery and pooled wild populations in terms of allelic richness (A _R), observed heterozygosity (H _O), and inbreeding coefficient (F _IS). Analysis of molecular variance and pairwise F _ST comparisons suggested significant genetic differentiation between hatchery strains and between hatchery and wild populations, which was further confirmed by principal components analysis and Bayesian clustering analysis. Bayesian genetic alignment showed high self-assignment accuracy (ranging from 86.0 to 96.0%) in the original populations, demonstrating the ability of this technique to identify hatchery Oujiang color common carp escapees in the wild population.     

Genetic variation of hatchery and wild stocks of the pearl oyster <Emphasis Type="Italic">Pinctada fucata martensii</Emphasis> (Dunker, 1872), assessed by mitochondrial DNA analysis

In order to provide baseline information for the genetic resources, genetic variation in wild and cultured Pinctada fucata martensii from southern Korea and Japan was studied using nucleotide sequence analysis of 379 base pairs (bp) in the mitochondrial cytochrome oxidase subunit I gene (COI). The study included three hatchery stocks from Korea (Tongyeong) and Japan (Mie and Tsushima) and one wild stock from Korea (Geoje). A total of 3 haplotypes were identified in hatchery stocks of 78 individuals, of which 63 individuals shared 1 haplotype. Overall, nucleotide diversity (π) was low, ranging from 0.000 to 0.002, and haplotype diversity (h) ranged from 0.000 to 0.541. Considerably low haplotype and nucleotide diversities in hatchery stock indicated that low effective population size and consecutive selective breeding of P. fucata martensii could be responsible for the reduction in genetic variation. The wild stock exhibited low haplotype diversity (0.507 ± 0.039) with two shared haplotypes. The results of the present study with first record of wild pearl oyster in Korea support the possibility that the transplanted pearl oyster for overwintering experiments could have survived in winter. In order to enhance and/or maintain genetic diversity in the hatchery stock, further research should be directed toward genetic monitoring and evaluation of the hatchery and wild pearl oysters.