遗传连锁图谱及其在鱼类遗传育种中的应用

基因组图谱的构建 ,是遗传学研究的一个重要领域 ,它是对基因组进行系统性研究的基础 ,也是动植物遗传育种和人类遗传病诊断的依据 ,它将使标记辅助选择技术的应用成为现实 ,从而可能从根本上改变传统的育种方法 ,进一步改良畜禽品种和大幅度提高畜禽生产效率。因此 ,从 1 91 3年 ,ＡＨＳｔｕｒｔｅｖａｎｔ在果蝇的性染色体上确定了 6个性连锁位点 ,构建了第 1张连锁图至今 ,科学家已经在人类及动植物的基因图谱构建方面做了大量的工作。近年来 ,许多国家投入大量的人力、物力 ,对陆生农业经济作物及牛、猪、鸡等畜禽进行了遗传图谱的构建…     

国外对鱼类多倍体育种的研究

在育种学上，多倍体与雌核发育的人工诱导都属于“染色体组工程”(Genome englneerlng)的范畴。由于它们有控制染色体组和性别的潜力，因此这些技术正在引起人们的浓厚兴趣。虽然鱼类的遗传育种工作起步较慢，但最近十五年来却十分活跃。本文拟对国外有关鱼类多倍体育种方面的研究现状及其动向作一综合评述，供国内同仁参考。     

我国养殖鱼类育种技术概况

我国渔业产量和养殖规模近年来一直居世界首位,但依然缺少高效、优质、抗病力强的养殖品种.如何通过传统育种和生物技术对鱼类进行品种选育和遗传改良,以获得优良性状的苗种,将对促进水产养殖业向高产、优质、持续、健康方向发展具有重要的意义.本文就我国养殖鱼类育种技术研究作一扼要的概述.     

主要养殖鲑科鱼类遗传育种的研究进展

冷水性鲑科鱼类肉质鲜美,高蛋白、高不饱和脂肪酸、营养丰富、无肌间刺、易加工,是世界性养殖鱼类,其中大西洋鲑、虹鳟和红点鲑属鱼类等主要养殖鲑科鱼类,一直是水产遗传育种领域的重要研究对象。本文简要叙述了鲑科鱼类遗传育种研究的历史和现状,主要介绍了经济性状遗传参数估计、选择育种、分子遗传与标记辅助育种等方面的研究进展,提出了我国鲑科鱼类遗传育种工作重点研究的方向。     

鱼类性别遗传标记研究进展

鱼类的性别遗传机制正处于分化的初级阶段,其性别决定受环境因素和遗传因素的共同控制,其性别决定机制比较复杂.一直以来鱼类与性别连锁的遗传标记的研究备受到关注,近年来在分子标记方面的研究取得一些进展.本文从表型标记、蛋白质标记和DNA分子标记三方面对鱼类的性别决定和性别遗传标记研究现状进行综述,着重介绍鱼类DNA水平上的性别遗传标记的研究进展,为鱼类的性别标记及性别控制研究提供基础资料.     

人工雌核发育在鱼类遗传育种中的应用

阐述了鱼类人工雌核发育的基本原理,介绍了人工雌核发育在研究鱼类性别决定机制,养殖生产中的性别控制和鱼类性别遗传机制分析及选育新品种等方面的应用成果。     

关于贝类遗传改良几个问题的讨论

贝类大多为雌雄异体,少数种类是雌雄同体,在雌雄异体的种类也有部分个体表现为雌雄同体,而且雌雄异体型贝类还常有性转变现象。养殖贝类大多行体外受精并具有配子量大、子裔数量多等特点。野生型贝类表型方差大,遗传变异水平高。可见,贝类是一群比较独特的动物,其生殖方面的某些特性与作物的共同点甚至超过与高等动物的共同点。因此仅依靠脊椎动物或植物的育种方法,难以解决好贝类的种质改良问题。     

Genetic variation in the growth traits of straight-bred and crossbred black bream (Acanthopagrus butcheri Munro) at 90 days of age

The current slow growth rate of black bream (Acanthopagrus butcheri Munro) impedes their widespread commercial aquaculture across inland southern Australia. We report initial estimates of genetic variation for growth traits at 90 days of age from a diallel cross using two black bream populations. Standard length, total length, and wet weight varied significantly among lines and among half‐sib groups within lines. Differences among half‐sib groups explained 6.8% of the total variance in standard length, 8.3% in total length, and 7.1% in wet weight, giving estimated heritabilities over all lines of 0.27±0.11 for standard length, 0.33±0.13 for total length, and 0.28±0.12 for wet weight. There was no evidence for heterosis in any traits when straight‐bred and crossbred lines were compared. There were high phenotypic (r_P=0.95–0.98) and genetic (r_G=0.63–0.69) correlations among all growth traits.     

Genetic improvement for important farmed aquaculture species with a reference to carp,tilapia and prawns in Asia: achievements,lessons and challenges

This study provides an overview of successful genetic improvement programmes for important farmed aquaculture species in Asia, with a focus on lessons and experiences gained as well as challenges remaining. In both fish and prawns (Macrobrachium rosenbergii), conventional selective breeding approaches have resulted in significant improvement in productivity, with genetic gains ranging from 8 to 12% per generation. Selection for high growth has also brought about beneficial changes in fillet weight of fish and edible meat in prawns without detrimental effects on flesh quality attributes and fitness‐related traits. Genetically improved animals show remarkable vigour and high adaptation to a range of culture environments/conditions in Asian countries. Despite these successes, however, the conduct and practical implementation of such breeding programmes still present several challenges. These include the expansion of breeding objectives, management of inbreeding in closed‐selection populations, controlling the effects of genotype by environment interactions, simultaneous production of large number of full‐ and half‐sib families for species with asynchronous spawning behaviour, maintaining pedigree records, dissemination of the improved strains for widespread production, as well as a reluctance by many to carry out systematically designed genetic improvement for aquatic animal species. There are also challenges with regard to the application of genomic information in genetic enhancement programmes and the development of genetically improved strains in response to climate and environmental changes. In this study, each of these challenges is discussed and solutions are proposed to increase efficiency of future genetic improvement programmes for economically important aquaculture species.     

Justification for genetic improvement in growth rates of black bream (Acanthopagrus butcheri): A partial budgeting analysis

Abstract

Black bream (Acanthopagrus butcheri) appear an ideal candidate for the developing saline aquaculture industry of inland Western Australia. However, current maximum growth rates of 150g/annum are too slow for profitable production. This study investigated whether enhanced growth rates of black bream would improve profitability and justify a genetic improvement program. A partial budget analysis was conducted for two different fish production systems; a commercial operation that incurred more operating expenses due to costs associated with farm initiation (stand‐alone farm model), and an existing farm that diversified into aquaculture using the saline water resources of established farm dams (integrated farm model). Sensitivity analyses indicated that a 33 per cent increase in growth rate to at least 200g/annum would allow either production system to return a profit at a farm‐gate price of AUS$6/kg whole fish, with fish survival rates of 98 per cent for the stand‐alone farm, and 65 per cent for the integrated farm model. These results are discussed in the context of the genetic and economic consequences of selection for improved growth rates, and for developing breeding objectives and a genetic improvement program for black bream.     

Genetic basis of Colossoma macropomum broodstock: Perspectives for an improvement program

Tambaqui, Colossoma macropomum (CUVIER, 1818), is the most farmed fish in Brazil. Endemic to the Amazonas and Orinoco basins, it is currently raised in all Brazillian regions. The lack of basic genetic information on tambaqui broodstock has been one of the problems of improvement programs in the species. The goal of this study is to provide information on the genetic basis of tambaqui broodstock from six fish farms located in three different regions of Brazil for application in improvement programs. Thus, genetic analyses were conducted using 15 microsatellite loci. We observed that the broodstock of Biofish (NortB), Prosperidade (NortP), and Tajá (NortT) presented loss of genetic variability. However, their genetic diversity values are higher when compared with the broodstock from the AquaBrasil (improved, NortA) project, Brumado (SoutB), and Departamento Nacional de Obras Contra a Seca (DNOCS) (NorthD), respectively. Furthermore, the broodstock of DNOCS needs to be renovated or increased, and the AquaBrasil individuals need to be better evaluated to verify the improvement achieved in the improvement program. Thus, aimed at the improvement of tambaqui production in the fish farms analyzed, we recommend increasing the population size of the broodstock to avoid inbreeding.     

五个斑点叉尾群体的微卫星遗传多样性分析

用8对微卫星引物对1997-2004年引进的5个斑点叉尾群体进行遗传多样性分析,计算并统计等位基因数、多态信息含量（PIC）、杂合度、遗传相似性系数、遗传距离等参数。实验显示8个微卫星位点在5个斑点叉尾群体中共检测到42个等位基因,平均期望杂合度为0.6338～0.7320,表明其遗传多样性程度处于中等偏上水平。平均多态信息含量为0.5756～0.6869,说明基因座为高度多态基因座（PIC〉0.5）。群体间遗传相似系数为0.7504～0.9203。聚类分析显示,04群体与其他4个群体的亲缘关系较远。结果表明：引进的5个斑点叉尾群体均具有较高的遗传多样性,遗传信息丰富,遗传变异大,为良好的育种材料。     

鱼类性别决定的遗传基础研究概况

动物从受精卵发育到具有不同性别特征的个体是一个奇妙而又严谨的过程,是人类长期以来试图揭示的自然现象。上世纪90年代初在人类Y染色体上发现了性别决定基因SRY[1],进而发现了一个新的Sox基因家族[2]。上述基因的发现,促进了以哺乳类为代表的动物性别决定和分化机制研究。由于鱼类在脊椎动物中的特殊进化地位、庞大的种类数量以及显著的社会经济价值,鱼类的性别决定研究一直受到遗传和发育学者的重视。尽管离最终阐明鱼类性别决定的机制还有距离,但近20多年来鱼类性别决定的遗传基础研究已取得不少重要进展。本文试图根据现有文献资料,…     

Quantitative genetic properties of four measures of deformity in yellowtail kingfish Seriola lalandi Valenciennes, 1833

The main aim of this study was to estimate the heritability for four measures of deformity and their genetic associations with growth (body weight and length), carcass (fillet weight and yield) and flesh‐quality (fillet fat content) traits in yellowtail kingfish Seriola lalandi. The observed major deformities included lower jaw, nasal erosion, deformed operculum and skinny fish on 480 individuals from 22 families at Clean Seas Tuna Ltd. They were typically recorded as binary traits (presence or absence) and were analysed separately by both threshold generalized models and standard animal mixed models. Consistency of the models was evaluated by calculating simple Pearson correlation of breeding values of full‐sib families for jaw deformity. Genetic and phenotypic correlations among traits were estimated using a multitrait linear mixed model in ASReml. Both threshold and linear mixed model analysis showed that there is additive genetic variation in the four measures of deformity, with the estimates of heritability obtained from the former (threshold) models on liability scale ranging from 0.14 to 0.66 (SE 0.32–0.56) and from the latter (linear animal and sire) models on original (observed) scale, 0.01–0.23 (SE 0.03–0.16). When the estimates on the underlying liability were transformed to the observed scale (0, 1), they were generally consistent between threshold and linear mixed models. Phenotypic correlations among deformity traits were weak (close to zero). The genetic correlations among deformity traits were not significantly different from zero. Body weight and fillet carcass showed significant positive genetic correlations with jaw deformity (0.75 and 0.95, respectively). Genetic correlation between body weight and operculum was negative (?0.51, P < 0.05). The genetic correlations' estimates of body and carcass traits with other deformity were not significant due to their relatively high standard errors. Our results showed that there are prospects for genetic selection to improve deformity in yellowtail kingfish and that measures of deformity should be included in the recording scheme, breeding objectives and selection index in practical selective breeding programmes due to the antagonistic genetic correlations of deformed jaws with body and carcass performance.     

鱼类树突状细胞研究进展

树突状细胞(DCs)是目前已知的体内功能最强的抗原递呈细胞,是唯一能够激活初始T淋巴细胞反应的细胞,在先天性免疫、适应性免疫以及维持自身免疫耐受方面具有重要的作用,因此一直是免疫学研究的重要领域。本文简要综述了DCs的类型及其在动物体内的功能、各类DCs的细胞标记。总结了鱼类DCs的分离、纯化方法和形态学观察方法;现有研究表明,鱼类DCs具有吞噬细菌、刺激T细胞增殖、诱导CD4+T细胞的活化、表达DCs的标记基因、被Toll样受体的配体激活、迁移能力、引起混合淋巴细胞反应等生物学功能;不同鱼类DCs的分子标记并不完全一样;鱼类的头肾、肾、鳃、皮肤、胸腺、脾、肠等均有DCs的分布。目前,对鱼类DCs的研究虽然取得了一定进展,但仍有许多重要问题需要解决:①鱼类DCs目前缺乏明确的细胞标记,加强这方面的研究有助于提高鱼类DCs的分离、体内分布与功能的研究水平;②加强和完善鱼类DCs的分离、培养技术的研究,掌握各种鱼类DCs的分离培养方法;③加强鱼类DCs在抗原递呈中的功能研究,对深入分析鱼类免疫机理,合理设计和应用疫苗,具有重要的理论指导意义。     

微卫星标记对红鳍东方鲀繁殖的指导应用及遗传分析

利用已有设计的20个具有多态性的微卫星标记对16尾红鳍东方鲀亲鱼(10尾♂,6尾♀)的有效等位基因数、观望杂合度、期望杂合度、多态信息含量、遗传相似性系数、遗传距离等进行了检测.据此设计了10对亲鱼配组,获得10个子代家系.其中母本中16和8号的平均有效等位基因数和平均期望杂合度较其他亲本高,将其分别与3个父本配组,其他则参照遗传距离进行配组.于次年,对F110个家系的体质量、体长均值进行了比对,发现16♀与11♂配组得到的子代体质量、体长均值为最大.8♀和10♂配组得到的子代体质量、体长均值最小.结果表明,红鳍东方鲀子代杂种优势与亲本个体差异有关.