家蚕分子连锁图谱的构建及分子标记育种研究进展

国际蚕分子育种计划(International Silkworm Project)是Rhode Island大学的M.R.Goldsmith在1991年提出来的,也叫基因标记育种计划[1].该计划主要包括两步工作:第一步是制作蚕的分子基因图, 第二步是数量性状定位分析(简称QTL分析,也叫数量性状定位作图:QTL Mapping).最后利用分子标记直接在DNA水平进行重要经济性状(数量性状)的选择、固定,即实施"分子育种",用很短时间育成兼具高抗、强健、丝多、质优、易繁等特性的新蚕品种,本文对此进行简要介绍.     

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…     

应用复合单标记分析进行QTL检测和参数估计的研究

随着现代分子生物技术的进展,在整个基因组范围内系统地搜索影响数量性状的基因座(ＱＴＬ)已成为可能,这便是利用分子遗传标记,通过标记ＱＴＬ连锁分析来对ＱＴＬ进行检测和参数估计。目前对标记基因进行连锁分析的原理与方法相对成熟,而在标记ＱＴＬ连锁分析方面,仍然有许多值得研究的问题。根据简单的性质,本研究提出了一种新的基于单标记分析的ＱＴＬ定位方法———复合单标记分析(ＣＳＭ),并通过Ｍｏｎｔｅ-Ｃａｒｌｏ模拟,研究了在近交系设计(ＢＣ1)当中,不同因素(如标记密度、ＱＴＬ效应等)对ＱＴＬ检测效率及参数估计精度的影响,同时…     

栽培稻与普遍野生稻两个重要分类性状花药长度和柱头外露率的QTL分析

用江西东乡普通野生稻（简称东乡普野）和桂朝２号的１１５株的ＢＣ１群体,构成了１张长度为１４１８．２ｃＭ．包含１２０个ＲＦＬＰ标记的遗传图谱,该图谱除第１染色体短臂上的标记的顺序与日本水稻基因组计划发表的图谱不同外,其他染色体上相对应的标记的顺序及标记之间的遗传距离基本一致。对控制花药长度和柱头外露率这两个栽培稻和野生稻的重要分类性状的ＱＴＬ分析结果表明,控制花药长度的２个ＱＴＬｓ分别位于第２染色体Ｃ４２４～Ｇ３９和第９染色体Ｃ２８０７～Ｃ１２６３间;控制柱头外露率的２个ＱＴＬｓ分别位于第５染色体Ｒ２２８９～Ｒ１５５３间和第８染色体Ｇ１１４９～Ｒ１９６３间。这两个重要分类性状的ＱＴＬｓ定位,为进一步研究野生稻进化到栽培稻的分子进化机理提供了有益的信息。     

孙女设计中标记密度对QTL定位精确性的影响

采用蒙特卡罗方法分析了在孙女设计中不同的嫩体结构、性状遗传力、ＱＴＬ效应大小和ＱＴＬ在染色体上的位置中个因素不同水平组合下４种标记密度（标记间隔５ｃＭ,１０ｃＭ,２０ｃＭ、５０ｃＭ对ＱＴＬ定位精确性（以均方误ＭＳＥ为衡量指标）的影响,并从经济学角度探讨了应用于标记辅助选（ＭＡＳ）的ＱＴＬ定位的最佳标记密度。结果表明,一般说来,在各因素水平都较低时,ＭＳＥ随标记密度加大而下降的相对幅度也较 小,反之     

图位基因克隆

图位基因克隆是最近几十年中发展并逐步完善起来的基因分离及研究方法。紧密连锁分子标记的获得及ＤＮＡ大片段克隆文库的建立是顺利进行图位基因克隆的重要条件,而对于那些数量性状基因（ＱＴＬｓ）的克隆更显示了其优越性。     

分子育种与作物改良

所谓分子育种就是定向、有目的地对农作物品种的遗传进行改良和修饰。分子遗传学研究的不断深入为农作物的遗传改良提供了强有力的手段,特别是农作物质量性状和数量性状基因的标记、定位和克隆以及植物转基因方法的不断完善和成熟,展示了分子育种的诱人前景。１分子标记...     

基于三点测交的双标记 -QTL基因定位的相关方法

提出在测交群体中,对区间标记座位赋值后求其与待定位的数量性状表型值间的简单相关系数Ｒ,以此进行连锁测验,并且在一定条件下用Ｒ值求出该数量性状座位（ＱＴＬ）与各标记座位（ＭＬ）间的重组值。     

加性基因效应与分子标记回归方程的关系

控制数量性状的基因作用历来是遗传学工作者所关注的重要课题．本文对以正交表形式表现的共显性动物分子标记资料,根据加性效应基因控制的数量性状遗传模型配合了动物分子标记回归方程通式．结果表明：对以正交表形式表现的加性效应基因共显性分子标记资料配合的分子标记回归方程,可对加性等位基因的相对作用差加以估计,并可作为育种的依据．     

与西瓜野生种质抗枯萎病基因连锁的RAPD标记

运用ＲＡＰＤ技术,采用混合分组分析（ｂｕｌｋｅｄｓｅｇｒｅｇａｎｔａｎａｌｙｓｉｓ,ＢＳＡ）方法进行了西瓜（Ｃｉｔｒｕｌｌｕｓｌａｎａｔｕｓ（Ｔｈｕｎｂ．）Ｍａｎｓｆｅｌｄｖａｒ． ｃｉｔｒｏｉｄｅｓ） 野生种质ＰＩ２９６３４１ 抗枯萎病基因连锁的分子标记研究。研究结果表明：西瓜野生种质Ｐ１２９６３４１ 抗枯萎病生理小种１ 的抗性由单显性基因控制,ＲＡＰＤ标记ＯＰＰＯＬ／７００ 与其抗病基因连锁,其遗传距离为３０ ｃＭ（ｃｅｎｔｉｍｏｒｇａｎ）。这为进行抗病分子标记辅助选择,以及最终定位与克隆其抗病基因打下了良好基础。     

分子标记及其在鸟类分子生态学研究中的应用

分子生态学是一门相当新的分支学科,从前人的研究工作来看,分子标记在这个学科中应用非常广泛,本文描述了RFLP、RAPD、MinisatelliteDNA,MicrosatelliteDNA和AFLP这5个分子标记的优缺点及其在鸟类分子生态学中的应用和研究概况。     

Molecular targets in lymphomas

A large proportion of patients with lymphomas are curable with standard chemotherapy. There is a plateau, however, in cure rate with chemotherapy alone. Advances in molecular biology have led to a better understanding of the pathogenesis of lymphomas. This article provides examples of how molecular therapy is going to change the treatment of lymphomas.     

Molecular diagnosis in oncology

Recent advances of molecular genetics have exerted a noticeable effect on some areas of clinical medicine. A comprehensive understanding of the nature of hereditary tumors is frequently heralded as the most substantial practical achievement of molecular oncology. Proper diagnostic algorithms have already been developed for the vast majority of known familial cancer syndromes. Interestingly, an unexpectedly strong founder effect has been documented at least for some hereditary cancers occurring in Russia, which significantly simplifies the detection of the corresponding disease-associated gene variants. The number of tests aimed at customizing cancer treatment continues to grow every year. The EGFR mutation test is probably the most impressive one, as it predicts the lung cancer response or nonresponse to gefitinib or erlotinib with a really unprecedented accuracy. Approaches helping to determine the individual efficacy and safety profiles for fluoropyrimidines, platinum compounds, irinotecan, etc. are currently under development. Methods detecting residual amounts of disseminated cancer cells represent another popular avenue of research. These technologies are expected to improve the quality of prediction of local and distant metastases, facilitate monitoring of the minimal residual disease, and, in the long-term perspective, provide a tool for early cancer diagnosis. It should be emphasized that molecular detection of disseminated tumor cells is currently used mainly in research settings and is not yet incorporated into routine clinical practice.     

Molecular evolution in bacteria

Recent advances in microbiology and molecular biology have a unifying influence on our understanding of genetic diversity/similarity and evolutionary relationships in microorganisms. This article attempts to unify information from diverse areas such as microbiology, molecular biology, microbial physiology, clay crystal genes, metals-microbe-clay interactions and bacterial DNA restriction-modification systems (R-M) as they may apply to molecular evolution of bacteria. The possibility is discussed that the first informational molecules may have been catalytic RNA (micro-assembler) not DNA (now the master copy) and these first micro-assemblers may have been precursors of ribosomes.     

Molecular lesions in cancer

Summary Newer methods of identifying biochemical events associated with cancer include recombinant DNA technology, monoclonal antibodies and improved analysis of nuclear and other cell functions to determine specific events which occur commonly in cancer cells. One-gene products offer potential opportunities for new approaches to cancer treatment and the hope of inducing differentiation of cancer cells toward their normal counterparts. Studies on antigens which react with monoclonal antibodies offer the opportunity for Iepitope attack which may be effected by improved drugs or by design of totally new drugs to bind to specific reactive sites. The complexity and pleiomorphism of cancer do not permit predictions as to whether these approaches will be more effective than the empirical approach to cancer treatment.     

Molecular biology in biorheology

This presentation is aimed at giving some background information on molecular biology, thus serving as an introduction to the Symposium on Molecular Biorheology held during the Sixth International Congress of Biorheology in Vancouver. The papers presented at this Symposium indicate that the use of molecular biological techniques allows the understanding of normal and abnormal rheological properties of cells and organs at the molecular level. It is hoped that these examples will provide an impetus for us to open new frontiers of research in biorheology by taking advantage of the powerful tools developed from recent advances in molecular biology.