鱼类基因组结构研究——Ⅰ.染色体的限制性内切酶显带

本文报道了1种新的鱼类染色体研究方法——限制性内切酶显带技术。我们应用限制性内切酶Bsp631等分别对黄鳝和长春鳊的染色体进行显带处理,结果表明,Bsp631能使这两种鱼的染色体发生稳定的带纹分化:适度的处理产生多重的G-带状带型,而过度的处理则产生特殊的限制性内切酶抗性带型。根据显带结果分析,我们对鱼类染色体限制性内切酶显带的可行性和实用价值进行了讨论。     

II型限制性核酸内切酶在真核生物染色体显带中的应用

限制性核酸内切酶（简称限制酶)能切割DNA双链。已知的限制酶有I, II和III型三类。II型限制酶能识别专一核普酸序列,并在识别序列内有固定切割点,是分子生物学研究和基因工程重要工具酶。1980年,以II型限制酶处理印度鹿染色体,沿染色体纵轴得到选择消化结果^[16]。目前,限制酶这一应用研究发展成称为限制性核酸内切酶显带（Restriction endonuclease banding）的最新显带技术,已应用于哺乳类、鸟类、两栖类、鱼类和昆虫等真核生物。限制酶显带与其他显带法相比有其特点,特别在揭示异染色质的异质性方面有其独到之处。本文介绍此项技术的发展与现状,并指出需要进一步探索的几个主要方面。     

用限制酶显带和CMA_3/DA/DAPI荧光染色研究中国小型白兔染色体结构异染色质

限制性内切酶(restriction endonuclease)是一类能识别并切开特定DNA序列的核酸内切酶,利用限制酶处理甲醇、冰醋酸固定后的哺乳动物中期染色体标本,再经Giemsa染色,能产生不同的特征性带纹,这是近几年发展的一种新的显带技术。目前,除用于人的中期染色体研究外,     

用限制性内切酶HaeⅢ进行绦虫染色体G分带的研究

限制性内切酶(简称限制酶)是一类能识别并切开特定DNA序列的核酸内切酶。近几年来,一些作者用限制酶处理人和小鼠的中期染色体,观察到特征性的带纹,并且认为限制酶的显带作用与染色体上DNA片段的选择性抽提有关。这一新技术的应用,不     

幽门螺杆菌的基因分型方法及其应用

近几年,有关幽门螺杆菌（ＨＰ）基因分型方法及其应用的研究取得了很大进展。基因分型方法包括：质粒分型、限制性内切酶分型（ＲＥＡ）、核糖分型、染色体ＤＮＡ脉冲场凝胶电泳（ＰＦＧＥ）分型、多聚酶链反应限制性内切酶消化（ＰＣＲ－ＲＦＬＰ）分型、任意引物ＰＣＲ（ＡＰ－ＰＣＲ）分型、ＰＣＲ单链构型多态性（ＰＣＲ－ＳＳＣＰ）分型和核苷酸序列分析等。基因分型方法广泛用于ＨＰ的研究,如基因图的构建、感染复发、耐药机     

葱小孢子的染色体和核型研究

本文用胰酶－尿素双重处理法和ＳＳＧ法,分别进行了葱小孢子染色体螺旋的染色体Ｃ－带的显带研究。首次成功地获得了葱小孢子染色体螺旋和染色体Ｃ－带,螺旋图象清晰;染色本Ｃ－带与体细胞的基本一致,所有染色体上均显示出明显的末端带,但未出现次缢痕带,另外,研究了葱小孢子的核型,其结果与体细胞的核型基本一致,但有差异。作者认为小孢子的核型比体细胞的核型准确,更能反映出葱的核型特征。     

铜绿假单胞菌PIC－N萘降解基因的研究

铜绿假单胞菌（Ｐｓｅｕｄｏｍｏｎａｓａｅｒｕｇｉｎｏｓａ）ＰＩＣ－Ｎ对萘、邻苯二甲酸、水杨酸等有较强的氧化能力。发现该菌株以禁为底物可诱导产生芳香烃分解酶系。菌株中存在一个５７．４ｋｂ的质粒,经限制性内切酶ＨｉｎｄⅢ处理可产生７个片段,用限制性内切酶ＥｃｏＲⅠ处理可产生８个片段。将以限制性内切酶ＨｉｎｄⅢ部分酶切的片段克隆至大肠杆菌质粒ｐＭＦＹ４３上,获得２９个克隆株。通过对含有菌株ＰＩＣ－Ｎ质粒ＨｉｎｄⅢ片段的７个重组质粒进行限制酶分析,绘出了该质粒ＨｉｎｄⅢ内切酶７个切点的酶切图谱。     

铜绿假单胞菌PIC—N萘降解基因的研究

铜绿假单胞菌ＰＩＣ－Ｎ对萘、邻苯二甲酸、水杨酸等有较强的氧化能力。发现该菌株以萘为底物可诱导产生芳香烃分解酶系。菌株中存在一个５７．４ｋｂ的质粒,经限制性内切酶ＨｉｎｄⅢ处理可产生７个片段,用限制性内切酶ＥｃｏＲ Ⅰ处理可产生８个片段。将以限制性内切酶ＨｉｎｄⅢ部分酶切的片段克隆至大肠杆菌持ｐＭＦＹ４３上,获得２９个克隆株。通过对含有菌株ＰＩＣ－Ｎ质粒ＨｉｎｄⅢ片段的７个重组闰进行限制酶分析,绘出     

人神经生长因子低亲和力受体（p~（75）NGFR）cDNA的克隆及其在神经细胞中表达活性的初步研究

利用酸性异硫氰酸胍－酚－氯仿一步法从人胎儿基底前脑中提取总ＲＮＡ,用逆转录与聚合酶链反应相结合的ＲＴ－ＰＣＲ法,扩增出人神经生长因子低亲和力受体ｐ~（７５）ＮＧＦＲ基因ｃＤＮＡ,在限制性内切酶ＳｍａⅠ存在下的连接体系中,将扩增出的ｃＤＮＡ片段克隆入ｐＵＣ１２的ＳｍａⅠ位或,经限制性内切酶ＥｃｏＲⅠ和ＰｓｔⅠ酶切鉴定是否插入以及ＨｉｎｄⅢ酶切鉴定方向。将重组质粒中的ｐ~（７５）ＮＧＦＲ的ｃＤＮＡ再次亚克隆至ｐＵＣ１２载体中后,以其双链ＤＮＡ为模板,用末端终止法测出其全部核苷酸顺序,证实其核苷酸编码的ｐ~（７５）ＮＧＦＲ除两个碱基突变外,其余与文献完全一致。完整的ｐ~（７５）ＮＧＦＲ的ｃＤＮＡ分两步克隆到逆转录病毒表达载体ｐＸＴ－１,经ＰＡ３１７包装细胞株体外包装后、收集病毒上清转染条件不死性大鼠小脑神经细胞系Ｒ２．初步结果表明转染了ｐ~（７５）ＮＧＦＲ的Ｒ２细胞株去除ＮＧＦ培养时出现程序化死亡的典型特征梯型ＤＮＡ带。     

金沙江中游地区红山茶组植物的Giemsa C—带研究

研究了金沙江中游地区红山茶组植物的Ｇｉｅｍｓａ Ｃ一带。该地区的红山茶植物以四倍体为主,个别居群为二倍体或六倍体。居群间的Ｃ－带差异明显,Ｃ－带多出现在染色体端部。在四倍体和六倍体的Ｃ－带带型中,只能找到２条显相同Ｃ－带的同源染色体,通过与其它地区的红山茶植物进行比较,发现红山茶组植物的倍性从华东,华南经贵州,四川向云南逐渐增高,显Ｃ－带的染色体与染色体总数之比随倍性增加而减少。文中指出华东或华南     

A Unique Protease Cleavage Site Predicted in the Spike Protein of the Novel Pneumonia Coronavirus (2019-nCoV) Potentially Related to Viral Transmissibility

正Dear Editor,In December 2019, a novel human coronavirus caused an epidemic of severe pneumonia(Coronavirus Disease 2019,COVID-19) in Wuhan, Hubei, China(Wu et al. 2020; Zhu et al. 2020). So far, this virus has spread to all areas of China and even to other countries. The epidemic has caused 67,102 confirmed infections with 1526 fatal cases     

Curcuminoids as inhibitors of thioredoxin reductase: A receptor based pharmacophore study with distance mapping of the active site

Curcumin is the yellow pigment of turmeric that interacts irreversibly forming an adduct with thioredoxin reductase (TrxR), an enzyme responsible for redox control of cell and defence against oxidative stress. Docking at both the active sites of TrxR was performed to compare the potency of three naturally occurring curcuminoids, namely curcumin, demethoxy curcumin and bis-demethoxy curcumin. Results show that active sites of TrxR occur at the junction of E and F chains. Volume and area of both cavities is predicted. It has been concluded by distance mapping of the most active conformations that Se atom of catalytic residue SeCYS498, is at a distance of 3.56 from C13 of demethoxy curcumin at the E chain active site, whereas C13 carbon atom forms adduct with Se atom of SeCys 498. We report that at least one methoxy group in curcuminoids is necessary for interation with catalytic residues of thioredoxin. Pharmacophore of both active sites of the TrxR receptor for curcumin and demethoxy curcumin molecules has been drawn and proposed for design and synthesis of most probable potent antiproliferative synthetic drugs.     

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.     

Comparative morphology of the carpel in the Liliaceae: Hewardieae, Petrosavieae, and Tricyrteae

The young pistils in the melanthioid tribes, Hewardieae, Petrosavieae and Tricyrteae, are uniformly tricarpellate and syncarpous. They lack raphide idioblasts. All are multiovulate, with bitegmic ovules. The Petrosavieae are marked by the presence of septal glands and incomplete syncarpy. Tepals and stamens adhere to the ovary in the Hewardieae and the Petrosavieae but not in the Tricyrteae. Two vascular bundles occur in the stamens of the Hewartlieae and Tricyrtis latifolia. Ventral bundles in the upper part of the ovary of the Hewardieae are continuous with compound septal bundles and placental bundles in the lower part. Putative ventral bundles occur in the alternate position in the Tricyrteae and putative placental bundles in the opposite. position in the Petrosavieae. The dichtomously branched stigma in each carpel of the Tricyrteae is supplied by a bifurcated dorsal bundle.     

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