微卫星标记及其在鸟类中的应用

微卫星DNA作为一种分子标记,以其诸多优点被认为是各类遗传标记中最有价值的一种。目前已被广泛应用于鸟类的研究中。本文介绍了微卫星DNA标记的分布特点、突变机制和作为分子标记的特点,并综述了微卫星DNA标记在鸟类的亲权分析及种类鉴定、遗传图谱构建及基因定位、物种进化历史揭示和遗传多样性研究中应用现状。     

DNA分子标记技术及其在水产动物遗传上的应用研究

随着DNA分子标记技术的发展,其在动物遗传上发挥了重大作用,使用DNA分子标记可以观察到整个基因组的遗传多样性。目前,在水产养殖种类中使用的遗传标记主要包括线粒体DNA、RFLP、RAPD、AFLP、微卫星、SNP和EST标记。DNA分子标记的应用使得人们对水产养殖动物的遗传多样性、近亲繁殖、种类和品系鉴定以及遗传连锁图谱建立的研究都取得了很大进展,也加快了数量性状位点(QTL)基因的鉴定作为分子标记辅助选择(MAS)的研究。将这些标记技术在水产动物上的应用进行了论述,以及如何从人类基因组工程和斑马鱼这种模式鱼的研究中得到启发,更好的应用于水产动物基因组学和遗传学研究做一讨论。     

SCoT分子标记在植物研究中的应用进展

SCo T是一种新型的目的基因分子标记,该标记不仅能获得与性状联系紧密的目的基因,而且能对性状进行跟踪,已被广泛应用于多种植物的研究。本文概述了SCo T标记的原理、引物设计方法及特点,并从PCR反应体系建立与优化、种质资源遗传多样性与亲缘关系分析、种质鉴定与指纹图谱构建、基因差异表达与分子遗传连锁图谱构建等方面总结了SCo T标记的应用进展。同时,对其存在的问题进行了讨论,并展望了该标记的发展应用前景。     

作物抗旱相关性状的QTLs定位研究进展

提高作物品种的抗旱性、获得高产稳产是抗旱育种的最终目标。作物分子连锁图谱的构建及其它分子遗传学研究进展为改良作物抗旱性提供了新机遇。Ｔａｎｋｓｌｅｙ等[1]指出,通过ＲＦＬＰ或其他分子标记进行标记辅助选择,为难以测量的性状提供了一条重要的选择途径。通过对抗旱相关性状的数量性状位点(ＱＴＬｓ)的标记,就可以把复杂的性状作为一套单基因性状进行分析和选择。一旦找到紧密连锁的标记(1-5ｃＭ),就可以在育种工作中进行标记辅助选择[2]。分子标记使育种家无需测定表型就能够追踪调控抗旱性状的遗传位点,可免去多年多点的大量田间…     

AFLP分子标记及其应用(综述)

本文简述ＡＦＬＰ分子标记的原理、方法与特点,并综述其在植物遗传多态性及系统发育学研究、基因定位及高密度遗传图谱（或物理图谱）构建和品种鉴定及抗性育种特征性状的分子标记中的应用现状和前景。     

豌豆遗传图谱构建及QTL定位研究进展

豌豆的许多性状是多基因控制的数量性状,QTL定位就是以分子标记技术为工具、以遗传连锁图谱为基础、利用分子标记与QTL之间的连锁关系确定控制数量性状的基因在基因组中的位置.本文对QTL定位原理、方法进行了简单介绍;对豌豆遗传图谱构建及主要性状,如产量、品质、抗病性等QTL定位、遗传效应分析等方面的研究进行综述;对目前基于QTL豌豆分子标记育种存在的问题、应用前景进行了探讨.     

AFLP分子标记及其应用（综述）

本文简述ＡＦＬＰ分子标记的原理、方法与特点,并综述其在植物遗传多态性及系统发育学研究、基因定位及高密度遗传图谱（或物理图谱）构建和品种鉴定及抗性育种特性性状的分子标记中的应用现状和前景。     

奶牛重要经济性状全基因组关联分析研究进展

产奶性状是奶牛最重要的生产性状, 随着平衡育种理念的提出和发展, 繁殖性状、体型性状、健康性状和长寿性等功能性状也逐渐被重视并纳入育种规划中。鉴定产奶性状和功能性状主效基因或遗传标记并将之应用于奶牛标记辅助选择可望加快遗传进展。随着高密度SNP标记的高通量检测技术的发展, 全基因组关联分析已成为鉴定畜禽重要经济性状基因的重要途径。文章对奶牛产奶性状和功能性状全基因组关联分析研究进展进行综述。     

分子标记在烟草性状连锁基因定位中的应用进展简

简要综述了分子标记在烟草性状连锁基因定位中的应用进展,包括烟草化学、普通农艺和抗病性等性状,讨论了其存在的问题及应用前景,以期为分子标记应用于烟草性状连锁基因定位和特色优质烟叶育种分子标记辅助选择研究的进一步发展提供借鉴。     

奶牛重要经济性状全基因组关联分析研究进展

产奶性状是奶牛最重要的生产性状,随着平衡育种理念的提出和发展,繁殖性状、体型性状、健康性状和长寿性等功能性状也逐渐被重视并纳入育种规划中。鉴定产奶性状和功能性状主效基因或遗传标记并将之应用于奶牛标记辅助选择可望加快遗传进展。随着高密度SNP标记的高通量检测技术的发展,全基因组关联分析已成为鉴定畜禽重要经济性状基因的重要途径。文章对奶牛产奶性状和功能性状全基因组关联分析研究进展进行综述。     

Genetic linkage map of rye (Secale cereale L.)

Communicated by G. Wenzel     

高梁基因组学研究的新进展

高梁是全球第五大禾谷类作物,在干旱、半干旱地区农业生产中占有权其重要的位置。高梁基因组相对较小(750Mbp),遗传多样性丰富,被认为是禾谷类作物比较基因组学研究的模式基因组之一。近年来,综合运用AFLP等分子标记、BAC文库、EST及cDNA作图和FIsH技术,加速了高梁高分辨率基因组图谱的构建。高梁基因测序、基因功能鉴定和克隆,以及遗传转化,亦取得了长足的进展。高梁特有的多种适应逆境胁迫等优异基因资源的发掘及其在作物改良中的应用前景广阔。     

Casares’ map function: no need for a ‘corrected’ Haldane’s map function

A genetic map function M(d) = RF provides a mapping from the additive genetic distance d to the non-additive recombination fraction RF between a given pair of loci, where the recombination fraction is the proportion of gametes that are recombinant between the two loci. Genetic map functions are needed because in most experiments all we can directly observe are the recombination events. However, since a recombination event is only observed if there are an odd number of crossovers between the two loci, recombination fractions are not additive. One of the most widely used map functions is Haldane’s map function, which is derived under the assumptions of no chiasma and no chromatid interference, and has been in widespread use since 1919. However, Casares recently proposed a ‘corrected’ Haldane’s map function – we show here that this ‘corrected’ map function is not correct due to faulty assumptions and mistakes in its derivation.     

A corrected Haldane’s map function to calculate genetic distances from recombination data

The estimation of genetic distances from recombination data has no direct relationship due to the fact that multiple crossovers do not generate recombinant gametes that can be recognized in the progeny. The Haldane’s map function is the most widely used mathematical formulation able to relate the observed recombination frequency with the actual number of crossovers. Here I show that the model in which the Haldane’s correction is based on is not correct, and I present a modified map function that takes into consideration the actual number of recombinant gametes produced in cells in which different number of crossovers have occurred. My correction generates shorter genetic distances than the Haldane’s one.     

A sex-averaged genetic linkage map in coastal Douglas-fir (Pseudotsuga menziesii[Mirb.] Franco var ‘menziesii’) based on RFLP and RAPD markers

 We have constructed a sex-averaged genetic linkage map in coastal Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco var ‘menziesii’) using a three-generation outcrossed pedigree and molecular markers. Our research objectives are to learn about genome organization and to identify markers associated with adaptive traits. The map reported here is comprised of 141 markers organized into 17 linkage groups and covers 1,062 centiMorgans (cM). Of the markers positioned on the map, 94 were derived from a Douglas-fir complimentary-DNA (cDNA) library that was constructed from new-growth needle tissue. Other markers include 11 Douglas-fir genomic-DNAs, 20 loblolly pine (Pinus taeda L.) cDNAs, 15 random amplified polymorphic DNAs (RAPDs) and a PCR-amplified phytochrome probe. A high degree of variation was detected in each of the two parents of our mapping population, and many of the restriction fragment length polymorphism (RFLP) and RAPD phenotypes were complex. Marker data were analyzed for linkage using mapping software JOINMAP version 2.0. Received: 16 March 1998 / Accepted: 22 April 1998     

水稻遗传转化研究进展

水稻遗传转化的主要方法,包括农杆菌介导法,基因枪法,电激法,PEG法等,论述了用于水稻转化的各种外植体,影响水稻遗传转化和植株分化的各种因素,各种标记基因及相应的选择方法和外源基因在转基因水稻中的遗传规律,比较了常用启动子在水稻中的表达强度,一些已转移到优良水稻品种中的有益农艺性状基因,如抗病、抗虫、抗除草剂等,介绍了它们在水稻品种改良中所发挥的作用。     

The density distribution of gene loci over the genetic map ofEscherichia coli: Its structural,functional and evolutionary implications

Summary A quantitative analysis was carried out on the dispersion of gene loci over theE. coli genetic map. Therefore, the map was divided into regions characterized by an homogeneous gene density. This created a distribution pattern of gene loci that contained a symmetry axis located near to the origin of DNA replication. The pattern could be subdivided into a set of 22 functional domains containing gene loci whose products revealed a biochemical or functional relatedness. A correlation was found between the boundary positions of these domains and the distribution of F plasmid- and DNA insertion sites over theE. coli chromosome. The structural, functional and evolutionary implications of these findings are discussed.     

Inheritance and linkage relationships of isozyme and morphological loci in cucumber (Cucumis sativus L.)

Twenty-one polymorphic and 17 monomorphic cucumber (Cucumis sativus L.) isozyme loci were identified in 15 enzyme systems. Seven of the polymorphic loci (Ak-2, Ak-3, Fdp-1, Fdp-2, Mpi-1, Pep-gl, and Skdh) had not been described previously. Segregation in F₂ and BC families for isozyme and morphological loci demonstrated agreement with the expected 121 and 11 segregation ratio (P<0.01). Nine morphological markers were found to be linked to isozyme loci and were integrated to form a map containing four linkage groups spanning 584 cM with a mean linkage distance of approximately 19 cM. Linkage groups (A to D) contain the following loci in genetic order: A psl, Pep-la, B, Per, dm, Pgm, Mpi-1, Idh, Ar, Fdp-1, Ak-2, Pgd-1, Mpi-2 and gl; B lh, Mdh-2, Pep-gl, Pgd-2, Fdp-2, Ccu, Mdh-3, Ak-3, ll, de, F and Mdh-1, and Gr; C cor, Gpi, and Skdh; D Tu and ss. This study detected four new linkages between morphological markers (dm-psl, de-ll, ll-F, and de-F) and confirmed previously reported linkages, dm-Ar and Tu-ss. The isozyme/morphological map constructed in this study led to a more comprehensive understanding of the genetic relationships between several economically important traits.Mention of a trade name, proprietary product, or specific equipment does not constitute a guarantee or warranty by the USDA and does not imply its approval to the exclusion of other products that may be suitable.     

Engineering of interstitial foreign chromosome segments containing the K+/Na+ selectivity gene Kna1 by sequential homoeologous recombination in durum wheat

Targeted homoeologous recombination mediated by the absence of the Ph1 locus is currently the most efficient technique by which foreign genes can be introgressed into polyploid wheat species. Because intra-arm homoeologous double cross-overs are rare, introgressed foreign genes are usually on terminal foreign chromosome segments. Since the minimum length of such a segment is determined by the position of a gene in the chromosome, large chromosome segments with undesirable genetic effects are often introgressed. Introgression of foreign genes on short interstitial segments based on two cycles of homoeologous recombination is described here. The utility of the technique is demonstrated by the introgression of the Kna1 locus, which controls K⁺/Na⁺ selectivity in T. aesivum L., on short interstitial segments of chromosome 4D into chromosome 4B of Triticum turgidum L. The level of recombination in a homoeologous segment is not significantly affected by a juxtaposed proximal homologous segment in the absence of the Ph1 locus.     

Comparative genome mapping reveals evidence of gene conversion between Sox9 paralogs of rainbow trout (Oncorhynchus mykiss)

Considerable evidence suggests that one genome duplication event preceded the divergence of teleost fishes and a second genome duplication event occurred before the radiation of teleosts of the family Salmonidae. Two Sox9 genes have been isolated from a number of teleosts and are called Sox9a and Sox9b. Two Sox9 gene copies have also been isolated from rainbow trout, a salmonid fish and are called Sox9 and Sox9α2. Previous evaluations of the evolutionary history of rainbow trout Sox9 gene copies using phylogenetic reconstructions of their coding regions indicated that they both belong to the Sox9b clade. In this study, we determine the true evolutionary history of Sox9 gene copies in rainbow trout. We show that the locus referred to as Sox9 in rainbow trout is itself duplicated. Mapping of the duplicated Sox9 gene copies indicates that they are co-orthologs of Sox9b while mapping of Sox9α2 indicates that it is an ortholog of Sox9a. This relationship is supported by phylogenetic reconstruction of Sox9 gene copies in teleosts using their 3′ untranslated regions. The conflicting phylogenetic topology of Sox9 genes in rainbow trout indicates the occurrence of gene conversion events between Sox9 and Sox9α2 which is supported by a number of recombination analyses.