遗传标记在苜蓿遗传多样性研究中的应用

介绍了当前广泛应用的苜蓿遗传多样性研究技术及其研究现状,包括苜蓿Medicago形态学和等位酶分析、种质资源和种内杂合性、进化与亲缘关系、抗逆性以及遗传连锁作图等几个方面的研究概况,同时提出了今后苜蓿遗传多样性分子标记研究的重点发展方向.     

唐古拉山牦牛群体的母系遗传多样性及遗传结构分析

[目的]从分子水平上探究青海省唐古拉山牦牛群体的母系遗传多样性、群体遗传结构及其遗传背景。[方法] 对52头唐古拉山牦牛个体mtDNA D-loop区序列进行测定后,使用生物信息学软件分析确定其核苷酸变异位点和单倍型数目,计算单倍型多样度和核苷酸多样度大小,并进行系统发育分析。[结果] 在619 bp唐古拉山牦牛D-loop区序列分析中,排除2处插入（缺失）后共检测到31处多态位点,包括单一多态位点5处和简约信息位点26处。根据序列间核苷酸变异共确定了13种单倍型,单倍型多样度和核苷酸多样度分别为0.821±0.043和0.007±0.004。与我国其他18个家牦牛品种和野牦牛相比,唐古拉山牦牛群体单倍型多样度和核苷酸多样度值均较低,表明该群体遗传变异较为贫乏,母系遗传多样性水平较低。以美洲野牛为外群,邻接法（即NJ法）构建的系统发育树结果显示：唐古拉山牦牛群体13种单倍型分布在A、B、C、D和E五种单倍型组中,且聚为2个大的母系分支（即I和II）,支系Ⅰ占比为77%,提示唐古拉山牦牛由2个母系支系组成,拥有2个母系起源且以支系Ⅰ为主。 [结论] 唐古拉山牦牛母系遗传多样性水平较低,由2个母系支系组成,以支系Ⅰ为主,推测其有2个母系起源。     

Molecular genetic diversity and genetic structure of Vietnamese indigenous pig populations

The study characterized genetic diversity and genetic structure of five indigenous pig populations (Ha Lang, Muong Te, Mong Cai, Lung and Lung Pu), two wild pig populations (Vietnamese and Thai wild pigs) and an exotic pig breed (Yorkshire) using FAO/ISAG recommended 16 microsatellite markers in 236 samples. All estimated loci were very polymorphic indicated by high values of polymorphism information content (from 0.76 in S0225 to 0.92 in Sw2410). Indigenous populations had very high level of genetic diversity (mean He = 0.75); of all indigenous breeds, Lung Pu showed highest mean number of alleles (MNA = 10.1), gene diversity (He = 0.82), allele richness (5.33) and number of private alleles (10). Thirteen percentage of the total genetic variation observed was due to differences among populations. The neighbour‐joining dendrogram obtained from Nei's standard genetic distance differentiated eight populations into four groups including Yorkshire, two wild populations, Mong Cai population and a group of four other indigenous populations. The Bayesian clustering with the admixture model implemented in Structure 2.1 indicated seven possible homogenous clusters among eight populations. From 79% (Ha Lang) to 98% (Mong Cai). individuals in indigenous pigs were assigned to their own populations. The results confirmed high level of genetic diversity and shed a new light on genetic structure of Vietnam indigenous pig populations.     

家禽遗传多样性的丢失

<正>据一位遗传学家的观点,尽管对禽流感、动物福利和消费者喜好等的关注影响了家禽行业的发展,但商用家禽品种遗传多样性的减少反面增强了家禽的弱点,同时     

New genetic parameters to exploit genetic variability in low input production systems

Under low input production systems, low heritabilities for growth traits have been a major limiting factor for recommending selection to improve animal productivity. Heritabilities low values were usually due to a large error variance leading to a dilution of the genetic variability. A total of 11,802 Barbarine lambs, from 606 breeding rams and 2428 breeding ewes, born during the period 1972–2002 and raised in a low production system were used in this study. The objective was to derive new genetic parameters that reflect in a proper way the available genetic variabilities for growth traits even under a low production system. Three classical heritability estimators and two new proposed genetic parameters (ratios) were computed and compared: the additive (h²a), the maternal (h²m), the total (h²t) heritabilities, the additive genetic ratio (a²) and the genetic maternal ratio (m²). Main results of this study showed that the direct animal model has led to higher heritability estimates than the animal maternal model. Estimates were 0.30, 0.30 and 0.31 for weights at 10 days, 30 days and 90 days, respectively. For average daily gains, estimates were 0.22 and 0.26 between 10–30 days and 30–90 days, respectively. Under maternal model, h²a varied from 0.05 to 0.08, h²m varied from 0.08 to 0.12 and h²t varied from 0.11 to 0.17. Maternal heritabilities were higher than additive heritabilities, but both remained relatively small. Values of additive genetic ratios were 0.20, 0.19, 0.20, 0.32 and 0.39 for W10, W30, W90 ADG13 and ADG39, respectively. The maternal genetic ratios were 0.41, 0.45, 0.37, 0.41 and 0.40 for W10, W30, W90, ADG13 and ADG39, respectively. These results showed that a² and m² describe better the contribution of the additive and maternal effects to the available genetic variability compared to classical heritability estimates because they remain unaffected by the residual error variance even under low-input production systems. These new parameters (ratios) represent, consequently, appropriate indicators for the contribution of the additive and maternal genetic effects to the total genetic variability and encourage breeders to find ways to exploit them.     

山丹马遗传资源调查

1 品种资源特点 1.1 山丹马产区自然资源条件山丹马是由原兰州军区军马总场(现名甘肃中牧山丹马场总场)培育的军马品种.山丹马的中心产区位于甘肃省河西走廊中段祁连山北麓,四周环山.场区自然生态环境比较恶劣,海拔高、气温低、降水量少、蒸发量大,植物多样性强.     

Estimation of accuracy and bias in genetic evaluations with genetic groups using sampling

Accuracy and bias of EBV are important measures of the quality of genetic evaluations. A sampling method that accounts for the uncertainty in the estimation of genetic group effects was used to calculate accuracy and bias of estimated effects. The method works by repeatedly simulating phenotypes for multiple traits for a defined data and pedigree structure. These simulated values are analyzed using BLUP with genetic groups in the relationship matrix. Accuracies and biases are then calculated as correlations among and differences between true and estimated values across all replicates, respectively. The method was applied to the Irish beef production data set for 15 traits and with 15 genetic groups to account for differences in breed means. Accuracy and bias of estimated genetic group effects, estimated comparisons between genetic group effects, EBV within genetic group, and EBV across genetic group were calculated. Small biases were detected for most estimated genetic group effects and most estimated comparisons between genetic group effects. Most of these were not important relative to the phenotypic SD of the traits involved. For example, a bias of 0.78% of the phenotypic SD was detected for carcass conformation in Aberdeen Angus. However, one trait, calf quality, which had few performance records in the data set, displayed larger bias, ranging from -10.31 to 5.85% of the phenotypic SD across the different estimated genetic group effects. Large differences were observed in the accuracies of genetic group effects, ranging from 0.02 for feed intake in Holstein, which had no data recorded, to >0.97 for carcass conformation, a trait with large amounts of data recorded in the different genetic groups. Large differences were also observed in the accuracies of the comparisons among genetic group effects. The accuracies of the EBV within genetic group and EBV across genetic group were sometimes different; for example, carcass conformation in Belgian Blue had an average accuracy within genetic group of 0.69 compared with an average accuracy across genetic group of 0.89. This suggests that the accuracy of genetic groups should be taken into account when publishing EBV across genetic groups.     

猪育种的遗传学研究进展

有效的表型度量方法是每一个猪育种计划的基石。     

Canine molecular genetic testing.

Inherited diseases are common among dogs. Recent advances in molecular genetics provide the groundwork for the development of genetic tests for the diagnosis and prevention of inherited diseases. As a result of this progress, genetics should become an integral part of veterinary medicine. DNA tests are safe, easy to perform, and reliable if interpreted correctly. Genetic tests only need to be performed once in a dog's lifetime, because the results of DNA testing never change. Veterinarians should be prepared to understand genetic testing and counseling because they are becoming increasingly important to veterinary medicine.     

如何发挥猪的遗传潜力

<正>对于养猪生产者而言,选择优良的品种和确保遗传潜力的充分发挥同样至关重要。一个围绕整个生产过程的方案,能够确保繁殖性能、生长效率和胴体质量取得最优化。     

Multiple bluetongue virus-cloned genetic probes: application to diagnostics and bluetongue virus genetic relationships

A shotgun-cloning method incorporating all 10 bluetongue virus genome segments can simultaneously produce complete and partial copies of any of the genome segments. We report here 4 different cloned probes derived from 3 genome segments and individually defined by different hybridization recognition capabilities. One probe hybridized strongly with all 5 United States prototype strains of the 5 different bluetongue virus (BTV) serotypes existing in the United States and, as such, is a strong candidate for a broad BTV diagnostic probe in the United States. Another probe derived from genome segment 2 of BTV-17 hybridized only with the BTV-17 prototypic serotype, thereby demonstrating serospecific hybridization diagnostic potential. The implications for diagnostic and genetic relationship studies on BTV, using various genetic probes, are discussed.     

现代蛋鸡品种的饲喂

高产蛋鸡品种几乎遍布全球.我们知道,每家一流的育种公司对其培育的各杂交蛋鸡鸡种的饲喂均有非常详细的建议.然而,Robert Pottgüter说,一些实际问题仍有待解决.     

如何获得猪的遗传潜力

<正>对于养猪生产者而言,选择优良的品种和确保遗传潜力的充分发挥同样至关重要。一个围绕整个生产过程的方案,能够确保繁殖性能、生长效率和胴体质量取得最优化。1优良的品种以一个能够适合终端市场需求并能够在生产环境中表现良好的品种开始自己的养猪事业是很重要的。因此,与育种公司进行交流,以了解他们的育种理念、目标以及健康监测规范,其目的是从中找到一家育种目标能够适合你要求的育种公司。价格决不应该是唯一     

基因克隆的几种常用方法

基因（ｇｅｎｅ）是遗传物质的最基本单位,也是所有生命活动的基础。不论要揭示某个基因的功能,还是要改变某个基因的功能,都必须首先将所要研究的基因克隆出来。特定基因的克隆是整个基因工程或分子生物学的起点。本文就基因克隆的几种常用方法介绍如下。１根据已知序...