黑麦2R染色体的显微分离与回收

建立了利用显微担任技术分离植物单个染色体的方法。以黑麦（Ｓｅｃａｌｅ ｃｅｒｅａｌｅ Ｌ）为材料,以其标准染色体组型图为依据,识别出黑麦含抗病基因的１Ｒ染色体。经显微操作,将单条１Ｒ染色体放入Ｅｐ－ｐｅｎｄｏｆ管中。研究表明,用α－溴萘饱和液对细胞进行预处理,可快速鉴别出黑麦１Ｒ染色体。采用去壁低渗制片技术,可明显地改善显微分离意境染色体的条件。     

黑麦1R染色体的显微分离、体外扩增及扩增产物的鉴定

借助Leitz显微操作器,在国产倒置显微镜下(400×)用玻璃针对处于有丝分裂中期的黑麦根尖细胞中的1R染色体成功地进行了分离。分离出来的1R染色体转入0.5 ml的Eppendorf管中,用蛋白酶K处理,把DNA释放出来;经Sau3A酶切,再与人工合成的Sau3A连接头连接;以连接头的一条链的核苷酸顺序片段为引物对DNA酶切片段进行了PCR扩增。琼脂糖凝胶电泳显示扩增产物的长度大约为300~1000 bp。以生物素分别标记的黑麦总体DNA和小麦rDNA为探针进行斑点杂交,结果表明PCR扩增产物确实来源于黑麦的1R染色体DNA。这个方法为构建黑麦1R染色体亚基因组文库和筛选1R染色体特异性探针奠定了基础。     

黑麦1R染色体微克隆文库的构建与分析

通过玻璃针分离法 ,从黑麦 (SecalecerealeL .)根尖细胞中期分裂相中显微分离出 2条及 5条 1R染色体。经Sau3A接头介导的PCR(LA_PCR)方法对其进行体外扩增 ,得到了 0 .3～ 2 .5kb之间的DNA片段。以DIG标记的探针进行多次Southern杂交 ,证明显微分离出的染色体的体外扩增产物与黑麦基因组DNA同源 ,并且来自 1R染色体。然后利用 5条 1R染色体的第二轮PCR产物构建质粒文库 ,可得到 2 2 0 0 0 0个重组子。随机挑选 172个重组子进行分析 ,发现插入片段主要介于 30 0～ 180 0bp之间。此外 ,根据基因组点杂交结果推算出该文库包含约 42 %的中、高重复序列和 5 8%的单、低拷贝序列 ,而且文库的冗余度较低。研究构建的黑麦 1R染色体微克隆文库为 1R染色体高密度遗传图谱的建立以及位于其上的重要基因的定位与分离提供了便利。     

黑麦染色体在小黑麦×小麦F_1花粉植株中的传递

对93株小黑麦×小麦的第一代花粉植株(H_1)进行细胞学观察,并用Giemsa分带技术鉴定其中的黑麦染色体,不同黑麦染色体表现出不同的传递频率。6R最高,1R、3R次之,7R最低。花粉植株中还发现黑麦染色体端体。     

小麦染色体的显微激光分离

探讨了应用氩离子激光进行植物染色体显微激光切割,分离的可行性,应用该技术对普通小麦的体细胞及特定染色体（１Ｂ染色体）实施切割,分离,并且以分离到的单细胞核或单条染色体为模板进行了ＰＣＲ ＤＮＡ扩增。该技术比玻璃针切割分离染色体技术,具有操作方便,容易掌握,且可对整个细胞核进行分离等优点,有利于促进染色体显微操作技术的普及应用。同时,探讨了染色体显微操作技术在细胞遗传学及分子生物学研究领域的应用前景     

黑麦染色体的显微分离与PCR扩增

利用改良的染色体显微分离技术,分离了黑麦（ＳｅｃａｌｅｃｅｒｅａｌｅＬ．）一个完整细胞的１８条染色体（１４Ａ＋４Ｂ）,用人工合成的寡核苷酸为引物,进行单一引物法（ｓｉｎｇｌｅｕｎｉｑｕｅｐｒｉｍｅｒＰＣＲ,ＳＵＰＰＣＲ）扩增,经Ｓｏｕｔｈｅｒｎ杂交证明,ＰＣＲ扩增产物与黑麦基因组ＤＮＡ同源。     

利用杀配子染色体2C诱导中国春-黑麦二体附加系染色体畸变的研究

将中国春-黑麦(1R-7R)二体附加系与中国春-2C(Aegilops cylindrica)二体附加系杂交,获得F1,对F1体细胞染色体进行C分带鉴定和花粉母细胞减数分裂行为的观察与分析,发现减数分裂行为异常。对自交获得的430株F2进行单株染色体C分带和荧光原位分子杂交鉴定,检测到易位、缺失、等臂染色体、双着丝点染色体等染色体畸变类型。此外还检测到2C与小麦2A、2B、2D染色体的二体或单体自发代换系。杂交F。染色体畸变的规律与频率如下：研究共得到含黑麦染色体的变异22株,变异频率为5,1％。其中含黑麦染色体的易位系为10株,占2,3％;缺失12株,占2．79％;黑麦的等臂染色体3株,占O．7％。易位染色体既有含小麦着丝点的(大部分),也含有黑麦着丝点的(仅1例)。黑麦的染色体畸变中,发生于不同同祖群的频率不同,1R为5个,2R为3个;3R为1个;4R为3个;5R为6个;6R为4个。易位多为端部易位。共鉴定出小麦的缺失系54株,其中A基因组有27个,占6.27％;B基因组有20个,占4,65％;D基因组有7个,占1.66％。对杀配子染色体对小麦及黑麦不同同祖群染色体作用的差异性及作用特点进行了探讨。     

小麦和黑麦染色体在小黑麦×小麦杂种的不同世代群体中的传递

使用单株植物C-带核型鉴定技术,研究了小麦和黑麦染色体在八倍体小黑麦×普通小麦的F_1,BC_1,F_2和F_3代中的遗传行为。黑麦染色体通过花粉和卵细胞的传递率显著不同,通过卵细胞丢失的染色体较多。黑麦染色体在F_2和F_3的传递率为36.0—38.8%,显著低于通过配子的平均传递率。不同的黑麦染色体通过配子的传递是随机的,而在F_2和F_3中却存在着显著的差异,1R的传递率最高,6R、7R最低。发生上述差异的原因可能是黑麦染色体的丢失不仅发生在配子形成和受精阶段,还受具有不同核型的受精卵在发育过程中夭亡的影响。受黑麦染色体的影响,小麦染色体也有不同程度的丢失。在不同的世代群体中,约有7.3—28.1%的植株丢失了小麦染色体。6R、5R和7R对小麦染色体丢失的作用较大。根据本研究的结果,在使用八倍体小黑麦×小麦的杂交方式利用黑麦遗传物质于小麦育种的工作中,F_2和F_3是有效选择的关键世代。本文建议的单株植物C-带核型鉴定技术是实现这一选择目标的有效方法。     

染色体显微操作技术及其应用

染色体显微操作技术及其应用何聪芬马有志辛志勇（中国农业科学院作物育种栽培研究所北京１０００８１）染色体显微操作技术起始于８０年代初,是一项特异性基因克隆技术［１］,其优点是能够根据研究者的需要分离任意一条染色体或特定染色体片段,快速高效地建立相应的ＤＮＡ文库。迄今已开发出三种染色体或染色体片段的分离技术,即流式细胞分类器法,微细玻璃针切割法和激光显微切割法［２］,本文将综述这三种方法的原理...     

小麦——黑麦染色体易位系的细胞学鉴定

用C－带技术分析了普通小麦“中国春”、黑麦“胜利”及小黑麦与普通小麦经辐射处理的后代中产生的并经多代纯化的5个带有黑麦某些性状的普通小麦品系的根尖染色体,结果表明：品系98－5－1为1A／1R纯合易位系,具有抗锈病、抗白粉病等基因,可作为诱导小片段易位的资源。作者提出在小麦－黑麦易位系鉴定中应用更高分辩率的G－带技术识别黑麦染色体片段或小片段易位。     

Recent advances in the study of Kaposi's sarcoma-associated herpesvirus replication and pathogenesis

It has now been over twenty years since a novel herpesviral genome was identified in Kaposi's sarcoma biopsies. Since then, the cumulative research effort by molecular biologists, virologists, clinicians, and epidemiologists alike has led to the extensive characterization of this tumor virus, Kaposi's sarcoma-associated herpesvirus(KSHV; also known as human herpesvirus 8(HHV-8)), and its associated diseases. Here we review the current knowledge of KSHV biology and pathogenesis, with a particular emphasis on new and exciting advances in the field of epigenetics. We also discuss the development and practicality of various cell culture and animal model systems to study KSHV replication and pathogenesis.     

The structure, reproduction and taxonomy of Vidalia and Osmundaria (Rhodophyta, Rhodomelaceae)

Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera.     

New or rare chromosome counts in Artemisia L. (Asteraceae, Anthemideae) and related genera from Kazakhstan

Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted.     

肝癌中HBV和HCV基因和抗原的分布及意义

采用原位分子杂交方法检测HCV RNA及HBV X基因;采用免疫组织化学方法研究HCV核心抗原,非结构区C33c抗原及HBxAg在肝细胞肝癌中的定位及分布.结果表明(1)HCV RNA、HBV X基因在肝细胞肝癌组织检出率分别为40%(55/136)和82%(112/136).HCV RNA定位于癌细胞的胞浆内,阳性细胞呈散在、灶状及弥漫分布三种形式;HBV X基因在肝癌细胞中的分布呈胞浆型、核型及核浆型,阳性细胞也呈上述三种分布形式;(2)HCV C33c抗原、核心抗原在肝细胞肝癌中的阳性率为81%(133/164)及86%(141/164).C33c抗原定位于癌细胞及肝细胞的胞浆内;核心抗原既定位于癌细胞核中,又可定位于胞浆中.C33c抗原阳性细胞以灶状分布为主;而核心抗原阳性细     

Selection with two alleles and complete dominance

For a plant selection model with frequency-independent viabilities, fertilities and selfing rates, it is shown that apart from global fixation, for certain parameter combinations a protected polymorphism and facultative fixation (either allele may become fixed according to initial frequencies) may both occur. Facultative fixation requires different selling rates for the dominant and recessive type. Protection of the polymorphism requires resource allocation for male and female function. In this connection the problem of purely genetically caused population extinction is discussed.
For general frequency dependence and regular segregation, the chances for establishment of a completely recessive gene are compared to those of a completely dominant gene. It is proven that the process of establishment of the recessive gene, despite a fitness advantage, may be considerably endangered by drift effects if random mating prevails. The recessive gene may reach the same effectivity in establishment as a dominant gene, only if the recessive homozygote mates exclusively with its own type during the period of establishment.