中国野生鹌鹑群体遗传共适应特性研究

随机抽取迁飞滞留季节捕获的野生日本鸣鹑40只、野生普通鹌鹑62只和家鹑40只, 采用蒙特卡罗模拟法检验群体遗传不平衡, 运用微卫星DNA标记对两种野生鹌鹑和家鹑群体的遗传共适应特性进行分析, 在3个鹌鹑群体中证实存在遗传共适应特性; 同时构建中性位点遗传共适应的统计模型, 分析遗传共适应特性在分子水平上的效应, 结果表明: 遗传共适应主导了野生日本鸣鹑、野生普通鹌鹑和家鹑群体的遗传不平衡状态, 分别有16.67%, 9.66%和10.05%的非等位基因组合因遗传共适应的影响处于遗传不平衡或极不平衡状态, 几乎所有检测的位点都存在遗传共适应特性, 其在分子水平上的作用更加显著, 维持着群体中大量的稳定多态现象. 这一结果丰富了群体遗传不平衡的概念和内涵, 为了解除连锁之外, 另一重要因素——遗传共适应对群体遗传不平衡的作用提供了科学的依据; 同时也为阐明我国野生鹌鹑的系统地位以及为评价、保护和利用我国野生鹌鹑这一宝贵遗传资源打下基础.     

辽东湾斑海豹遗传多样性的AFLP分析

利用AFLP标记技术对辽东湾斑海豹的遗传多样性进行分析。采用7对AFLP引物对斑海豹3个群体(按不同采样年份分类)43个个体扩增共得到241个位点,3个群体内的多态位点比例为80.45%～95.85%,总多态位点比例为99.59%。群体的香农(Shannon)多样性指数为0.3817～0.4716,群体间的遗传距离在0.1742～0.4023之间。2007年群体的多态位点比例、Shannon多样性指数均高于2006年群体,2005年群体处于中等水平。用NTSYS软件进行个体聚类及UPGMA方法构建的群体系统树,发现3个群体的个体基本随机聚到一起,界限不十分明显,说明3年的群体差异不明显,甚至可以认为它们是混合群体。结果表明,斑海豹群体遗传多样性水平较低,遗传结构趋于简单化,且存在较强的基因交流。     

用遗传标记监测不同环境和经营措施下的加勒比松森林群体遗传动态

对古巴加勒比松的6个群体（包括天然林、采伐林、母树林和种子园）进行了同功酶分析,根据5个酶系统8个位点的同功酶数据,对各群 交配系统以及群体遗传变异和结构进行了分析,天然林、种子园和母树林的多位点异交率和绝大多数单位点异交率都和完全异交无显著差异,过渡采伐的松树岛群体多位点异交率显著小于完全异交,而只有一半单位点异交率显著小于完全异交,而且该群体单位点平均异交率和多位点异交率均低于其它3个群体的估计值。采伐群体中同功酶变异和基因多样性与天然林群体JAG的相似,但低于其它群体,其近交系数较大,但小于天然林MAN和中国栽培群体的近交系数。中国引种栽培群体无论是同功酶变异还是基因多样性都显著高于古巴群体,与所有古巴群体的遗传距离都显著大于古巴群体之间的遗传距离。结果表明过度采伐导致群体自交程度增加,营建种子园可有效减少近交。自然分布区以外的引种栽培群体遗传变化量大,无论遗传变异和基因多样性都比参试其它群体大。     

亲本对后代群体的不均等遗传贡献及其优化控制

由于自然选择和人工选择的共同作用,使不同亲本的基因在后代基因库中所占比例有所不同,即亲本对后代群体的不均等遗传贡献。本文分析表明,不均等遗传贡献通过实现选择差和群体有效含量对遗传进展产生影响,并使传统的预估选择反应公式出现误差。育种的目标首先是找出在遗传上真正优秀的个体,同时还应当使越优秀的个体对后代基因库的遗传贡献越大。但后一方面尚未得到系统的研究。本文针对这一点,提出了以加快群体遗传进展为总目标、充分考虑育种约束条件的优化控制遗传贡献率的方法。对蛋鸡育种实际资料的计算结果表明,在同等群体含量水平下,优化不均等遗传贡献模式下所获得的实现选择差可比实际值提高34.27—216.57%。     

林木群体遗传多样性和多位点遗传结构

本文评述了群体同工酶基因位点遗传结构研究中的主要度量方法及其在森林树种中的应用概况。群体遗传结构可由单位点和多位点两类参数度量。 文中对这两类度量及其关系分别进行了讨论。阐明了多位点遗传结构的信息对林木改良和资源保存策略的重要意义。     

云贵高原银星竹鼠的遗传多样性与遗传结构研究

作为一类营地下生活的啮齿动物,银星竹鼠Rhizomys pruinosus具有较高的食用价值和药用价值,已成为我国南方地区特种经济动物养殖业的重点发展物种。以核内重组蛋白激活基因1(RAG1)的基因片段为分子标记,采用分子生物学方法,本研究对来自12个采样点的173个银星竹鼠个体进行群体遗传分析,探讨该物种群体遗传多样性和遗传结构。序列多态性分析结果显示,银星竹鼠RAG1基因部分序列848 bp,共检测出多态性位点18个,其中单突变位点3个,简约信息位点15个。遗传多样性分析表明,173份样本共统计出RAG1基因单倍型11个,单倍型多样性为0.712±0.025,核苷酸多样性为0.002 64±0.003 71,显著低于其他啮齿动物。最大似然法、邻接法和贝叶斯法构建的系统发育树显示,银星竹鼠群体分化为3个分支,其谱系地理格局出现明显分化。同时,分子变异分析结果证实,银星竹鼠种群间的遗传变异极显著高于种群内的,说明该物种存在显著的遗传结构和遗传分化水平。上述研究结果综合表明,银星竹鼠群体的遗传多样性水平较低,遗传分化结构较为显著,这可能与该物种的地下生活方式、扩散能力弱、山脉河流阻隔作用、地质气候事件等因素有关。本研究结果将为云贵高原地区物种多样性、生物多样性保护提供科学的参考依据。     

华南及邻近地区大刺鳅遗传多样性的ISSR分析

为了解我国大刺鳅野生资源状况, 研究采用ISSR技术分析了福建、广东、广西、云南和海南11个地理群体262尾大刺鳅的遗传多样性。10个引物共扩增出112个位点, 多态位点95个, 多态位点比例为84.82%。大刺鳅总群体Nei基因多样性h=0.2126、Shannon 信息指数I=0.3358, 表明大刺鳅总群体遗传多样性较丰富, 其中各群体遗传多样性依次为恩平 红河 屯昌 英德 河池 乐昌 增城 龙岩 五华 仁化 百色。总群体遗传分化系数Gst=0.4620, 显示46.2%的变异来自群体间。总群体基因流Nm=0.5823, 表明大刺鳅总群体间缺乏有效的基因交流, 遗传漂变是大刺鳅群体遗传分化的主要因素。聚类分析表明, 东江群体和韩江群体聚为一支, 西江群体和北江群体聚为一支, 大陆群体聚为一大支, 然后和海南屯昌群体聚类。     

罗氏沼虾不同群体线粒体COI基因的序列差异和遗传标记研究

利用PCR方法扩增获得罗氏沼虾（Macrobrachiumrosenbergii）线粒体DNA的COI基因,测定该基因片段序列。分析了罗氏沼虾缅甸原种F1代、江苏养殖群体和广西选育F2代3个群体共17只个体的序列核苷酸位点差异和遗传多态。结果表明,缅甸原种F1代遗传多样性最为丰富,江苏养殖群体和广西选育群体的遗传多样性相对贫乏。在长度为498bp的基因片段中,共检测到10个多态性核苷酸位点（占2.01%）,17只个体具有5种基因型,3群体各自的平均核苷酸位点差异分别为0.88%、0.07%和0。UPGMA分子系统聚类树显示,江苏养殖群体和广西选育群体的遗传关系最近,其单倍型混杂聚成一支,而缅甸原种F1群体相对独立为另外一支。COI基因可以作为区分两分支群体的遗传标记。     

2个中国藏獒群体遗传多样性及遗传分化的研究

本研究以青海土种犬和藏狮犬为对照,采用RAPD技术对河曲藏獒和青海藏獒群体的遗传多样性及遗传分化进行了分析.研究结果表明,河曲藏獒和青海藏獒群体的多态性位点百分率分别为85.53%和98.16%,平均多态性位点百分率为91.85%.藏獒群体遗传变异分析显示两个藏獒群体的有效等位基因数(Ne)、Nei氏平均预期基因杂合度(H)和Shannon遗传信息指数(I)的平均值分别为1.5354、0.3191和0.4807;且两个藏獒群体93.09%的变异来自群体内,仅6.91%变异来自群体间;两个群体间的基因流为3.3679.研究还发现两个藏獒群体之间的Nei氏标准遗传距离(D)为0.050 5.本研究结果说明藏獒群体内遗传变异丰富,不同地域的藏獒群体之间存在广泛的基因交流,群体之间遗传分化程度很低,这为藏獒品种资源保护与合理开发利用提供了参考.     

三个地理群体赤眼鳟遗传多样性的RAPD分析

利用RAPD技术对宿鸭湖、青龙湖和丹江口水库3个野生赤眼鳟群体的遗传多样性进行分析.9个RAPD引物共获得93个扩增位点,其中多态位点56个,多态位点比例为60.22%.3个群体的多态位点比例分别为53.01%、54.12%和57.95%,遗传距离分别为0.1548、0.1613和0.1764,Shannon信息指数分别为0.2249、0.2318和0.2437.群体间遗传距离以宿鸭湖和青龙湖群体最近(0.1257),青龙湖与丹江口水库群体最远(0.1416).结果表明3个赤眼鳟群体的遗传多样性均较丰富,但群体间地理遗传分化差异并不明显.     

群体遗传不平衡条件下的结构基因遗传共适应特性

本研究以柴达木山羊、柴达木绒山羊和辽宁绒山羊三个群体共147只山羊为材料,利用聚丙烯酰胺凝胶电泳（PAGE）技术检测了5种血液蛋白质（酶）基因座的遗传多态性,并进行了结构基因遗传共适应的研究,结果发现：45个基因座组合中有10个基因座组合处于遗传不平衡状态,并且这些遗传不平衡皆单纯由遗传共适应差异造成;除辽宁绒山羊Tf-PA-3组合的遗传不平衡包含非等位基因间的遗传共适应差异外,其他基因座组合的遗传不平衡皆由等位基因间的共适应差异,即单基因座的遗传不平衡造成;LAP-EsD组合的共适应差异在群体间有遗传传递现象。 Abstract:With the technology of PAGE,the genetic polymorphism of blood protein and enzyme was investigated,and genetic co-adaptability among structural genes was studied in three goat populations(147 goats) including Chaidamu goat(CS),Chaidamu Cashmere goat(CRS) and Liaoning Cashmere goat(LRS) in Qinghai Province,China.The results were showed that the genetic disequilibrium of 10 locus combinations was found among 45 locus combinations in the three goat populations,and these genetic disequilibria were caused only by the difference of genetic co-adaptability among genes,because there didn′t exist the linkage disequilibrium among non-allelic genes.The genetic disequilibrium including the difference of genetic co-adaptability between non-allelic genes was only found at Tf-PA-3 locus combinations in LRS population,the other ones were all caused by the genetic disequilibrium at a single locus.The difference of genetic co-adaptability of LAP-EsD locus combinations could be messaged among different populations.     

湖羊结构基因座遗传共适应性分析

根据多座位电泳法检测的结构基因座上等位基因频率分析湖羊群体的遗传共适应性。结果发现, 在显隐性－显隐性模式中未发现座位间的遗传共适应现象, 显隐性－共显性模式中X-p-Cat组合座位以及共显性－共显性模式中Po-CA、Po-Cat组合座位均存在遗传共适应, 表明在湖羊群体中性结构基因座间存在遗传共适应, 而且起主要的作用, 维持着座位间的遗传平衡或者使座位间处于遗传不平衡状态。     

Genomics of gene banks: A case study in rice

Only a small fraction of the naturally occurring genetic diversity available in the world's germplasm repositories has been explored to date, but this is expected to change with the advent of affordable, high-throughput genotyping and sequencing technology. It is now possible to examine genome-wide patterns of natural variation and link sequence polymorphisms with downstream phenotypic consequences. In this paper, we discuss how dramatic changes in the cost and efficiency of sequencing and genotyping are revolutionizing the way gene bank scientists approach the responsibilities of their job. Sequencing technology provides a set of tools that can be used to enhance the quality, efficiency, and cost-effectiveness of gene bank operations, the depth of scientific knowledge of gene bank holdings, and the level of public interest in natural variation. As a result, gene banks have the chance to take on new life. Previously seen as "warehouses" where seeds were diligently maintained, but evolutionarily frozen in time, gene banks could transform into vibrant research centers that actively investigate the genetic potential of their holdings. In this paper, we will discuss how genotyping and sequencing can be integrated into the activities of a modern gene bank to revolutionize the way scientists document the genetic identity of their accessions; track seed lots, varieties, and alleles; identify duplicates; and rationalize active collections, and how the availability of genomics data are likely to motivate innovative collaborations with the larger research and breeding communities to engage in systematic and rigorous phenotyping and multilocation evaluation of the genetic resources in gene banks around the world. The objective is to understand and eventually predict how variation at the DNA level helps determine the phenotypic potential of an individual or population. Leadership and vision are needed to coordinate the characterization of collections and to integrate genotypic and phenotypic information in ways that will illuminate the value of these resources. Genotyping of collections represents a powerful starting point that will enable gene banks to become more effective as stewards of crop biodiversity.     

Temporal patterns of genetic variation across a 9-year-old aerial seed bank of the shrub Banksia hookeriana (Proteaceae)

The pattern of accumulation of genetic variation over time in seed banks is poorly understood. We examined the genetic structure of the aerial seed bank of Banksia hookeriana within a single 15-year-old population in fire-prone southwestern Australia, and compared genetic variation between adults and each year of a 9-year-old seed bank using amplified fragment length polymorphism (AFLP). B. hookeriana is well suited to the study of seed bank dynamics due to the canopy storage of its seeds, and because each annual crop can be identified. A total of 304 seeds from nine crop years and five maternal plants were genotyped, along with 113 plants from the adult population. Genetic variation, as assessed by the proportion of polymorphic markers (P(p)) and Shannon's index (I), increased slightly within the seed bank over time, while gene diversity (H(j)), did not change. P(p), I, and H(j) all indicated that genetic variation within the seed bank quickly approached the maximal level detected. Analysis of molecular variance revealed that less than 4% of variation could be accounted for by variation among seeds produced in different years, whereas there was greater differentiation among maternal plants (12.7%), and among individual seeds produced by different maternal plants (83.4%). With increasing population age, offspring generated each year were slightly more outbred, as indicated by an increase in the mean number of nonmaternal markers per offspring. There were no significant differences for H(j) or I between adults and the seed bank. Viability of seeds decreased with age, such that the viability of 9-year-old seeds was half that of 2-year-old seeds. These results suggest that variable fire frequencies have only limited potential to influence the amount of genetic variation stored within the seed bank of B. hookeriana.     

Gene for Heat-Inducible Lysyl-tRNA Synthetase (lysU) Maps near cadA in Escherichia coli

A hybrid ColE1 plasmid from the Clarke-Carbon colony bank with a 7-kilobase insertion was found to encode the inducible lysyl-tRNA synthetase along with the catabolic enzyme lysine decarboxylase. The gene for the inducible synthetase, lysU, must lie within 0.3 min of the lysine decarboxylase gene, cadA, at 92 min on the Escherichia coli genetic map.     

Polymorphism in Nos2 gene is absent in Prague colony of Dahl/Rapp salt-sensitive and salt-resistant rats

We have searched for polymorphism of inducible nitric oxide synthase gene (Nos2 gene) in the Prague colony of salt-sensitive and salt-resistant Dahl/Rapp rats. Specific primers were used to confirm previously described Nos2 gene polymorphism because this gene was suggested to be a potential candidate gene for genetic hypertension. Phenotyping (blood pressure, organ weight, plasma lipids) have confirmed the data known from other colonies of Dahl/Rapp rats. However, in our colony we were not able to find any Nos2 gene polymorphism between salt-sensitive and salt-resistant rats, which was previously described in animals from Harlan colony. Moreover, the genetic homogeneity of our salt-sensitive and salt-resistant rats in terms of Nos2 gene was the same as in the original Brookhaven colony of Dahl rats. This is surprising because our colony has been established from breeding pairs kindly provided by Prof. J.P. Rapp more than 15 years ago. It seems that the polymorphism found in Harlan colony could be the result of previous contamination or genetic drift during the breeding conditions specific for this colony.     

4. In-vitro conservation

In-vitro (tissue culture) techniques offer ways of overcoming serious problems in the conservation of crop genetic resources. These primarily involve the use of slow growth and cryopreservation in liquid nitrogen to store germplasm, but there are also important applications in other areas, including germplasm collecting, multiplication and exchange. Slow growth techniques for medium-term storage of cultures are relatively well developed and in-vitro active gene bank establishment is feasible. Cryopreservation for long-term storage is possible for some materials but, in general, requires further research and development. Among the aspects to be examined are the behaviour of different culture systems when exposed to ultralow temperatures, crop-specific requirements and the genetic stability of stored material.     

Unused genetic resources: a case study of Polish common oat germplasm

Landraces and old, obsolete cultivars are a rich source of diversity and could become important and easy‐to‐use germplasm resources for breeding. They are characterised by yield stability, broad adaptation, tolerance to diseases and a greater competitiveness in the presence of weeds. The main objective of this study was to estimate and compare the genetic diversity among and within landraces, old cultivars and modern cultivars of common oat. Inter simple sequence repeats were used to study the genetic diversity of 12 modern Polish cultivars, 23 old Polish cultivars, 19 native landraces and 5 contemporary European cultivars. The results indicated a low amount of diversity among Polish modern cultivars, but an even lower diversity among old Polish cultivars, as well as large differences between these two gene pools. As expected, the landraces were the most diverse group and showed the highest internal variation. The landraces and old cultivars might serve as sources of useful alleles that have never been used in breeding. Additionally, it was possible to identify errors and inconsistencies in the passport data of gene‐bank accessions. These results can be applied to the maintenance and management of gene‐bank collections.     

Impact of river dynamics on the genetic variation of Gypsophila repens (Caryophyllaceae): a comparison of heath forest and more dynamic gravel bank populations along an alpine river

• Alpine rivers are, despite anthropogenic water flow regulation, still often highly dynamic ecosystems. Plant species occurring along these rivers are subject to ecological disturbance, mainly caused by seasonal flooding. Gypsophila repens typically grows at higher altitudes in the Alps, but also occurs at lower altitudes on gravel banks directly along the river and in heath forests at larger distances from the river. Populations on gravel banks are considered non‐permanent and it is assumed that new individuals originate from seed periodically washed down from higher altitudes. Populations in heath forests are, in contrast, permanent and not regularly provided with seeds from higher altitudes through flooding. If the genetic structure of this plant species is strongly affected by gene flow via seed dispersal, then higher levels of genetic diversity in populations but less differentiation among populations on gravel banks than in heath forests can be expected.
• In this study, we analysed genetic diversity within and differentiation among 15 populations of G. repens from gravel banks and heath forests along the alpine River Isar using amplified fragment length polymorphisms (AFLP).
• Genetic diversity was, as assumed, slightly higher in gravel bank than in heath forest populations, but genetic differentiation was, in contrast to our expectations, comparable among populations in both habitat types.
• Our study provides evidence for increased genetic diversity under conditions of higher ecological disturbance and increased seed dispersal on gravel banks. Similar levels of genetic differentiation among populations in both habitat types can be attributed to the species' long lifetime, a permanent soil seed bank and gene flow by pollinators among different habitats/locations.

     

Development of a Chinese-Indian hybrid (Chindian) rhesus macaque colony at the California National Primate Research Center by introgression

Background  Fullbred Chinese and Indian rhesus macaques represent genetically distinct populations. The California National Primate Research Center introduced Chinese founders into its Indian-derived rhesus colony in response to the 1978 Indian embargo on exportation of animals for research and the concern that loss of genetic variation in the closed colony would hamper research efforts. The resulting hybrid rhesus now number well over a thousand animals and represent a growing proportion of the animals in the colony.
Methods  We characterized the population genetic structure of the hybrid colony and compared it with that of their pure Indian and Chinese progenitors.
Results  The hybrid population contains higher genetic diversity and linkage disequilibrium than their full Indian progenitors and represents a resource with unique research applications.
Conclusions  The genetic diversity of the hybrids indicates that the strategy to introduce novel genes into the colony by hybridizing Chinese founders and their hybrid offspring with Indian-derived animals was successful.