利用18S和ITS序列揭示8种鲇形目鱼类的系统发育

为了探讨鲇形目(Siluriformes)鱼类系统发育关系,本研究克隆了黄颡鱼(Pelteobagrus fulvidraco)、长吻(Leiocassis longirostris)、斑鳠(Mystus guttatus)、革胡子鲇(Clarias gariepinus)、鲇鱼(Silurus asotus)和斑点叉尾(Ictalurus punctatus)6种鱼类的18S和两个内转录间隔区(包括全长ITS1-5.8S-ITS2)基因,结合GenBank中双须缺鳍鲇(Kryptopterus bicirrhis)和脂鳍胡鲇(Dinotopterus cunningtoni)的同源序列进行比较分析,结果表明,(1)8种鱼18S的长度为1814～1842bp,同源性达97%以上,5.8S均为157bp,同源性也高达99.36%～100%;(2)8种鱼ITS1长度为335～620bp,其中,黄颡鱼的最长,为618～620bp,斑点叉尾的最短,为335～336bp;ITS2长度为265～459bp,其中,脂鳍胡鲇最长,为459bp,斑点叉尾的最短,约为270bp。ITS1序列的同源性为29.45%～88.21%,其中,革胡子鲇和脂鳍胡鲇同源性最高,鲇鱼和革胡子鲇同源性最低。ITS2序列的同源性为41.59%～94.07%,其中,革胡子鲇和脂鳍胡鲇同源性最高,鲇鱼和革胡子鲇同源性最低;(3)分别以鲤鱼(Cyprinus carpio)18S和ITS为外群,采用NJ法构建18S、ITS系统发育树,结果显示,鲇科与胡鲇科的关系最近,鲿科与这两科关系较远,科与另外3科关系最远。鲿科中属和黄颡鱼属的关系较鳠属更近;胡鲇科的胡鲇属和脂鳍胡鲇属是关系很近的两个属;鲇科的鲇属和缺鳍鲇属是关系较远的两属。     

斑点胡子鲶和胡子鲶染色体组型的研究

斑点胡子鲶(Clarias macrocephalus)又称大头胡子鲶,是近年来从泰国引进的淡水养殖鱼类,它与生长在我国的胡子鲶(Clarias fuscus)形态和习性相近,在分类学上同属鲤形目、胡子鲶科、胡子鲶属。 斑点胡子鲶具有生长较快、体型较大、产量较高的优点,但也有肉味稍逊、耐寒力偏弱、养殖不易的缺点;而胡子鲶的优点是肉质细嫩、味美、抗寒力较强、养殖容易,其缺点是生长较慢、     

胡子鲇Dmrt1基因全长cDNA克隆及其表达分析

以胡子鲇(Clarias fuscus)为研究对象,利用RT-PCR技术和SMART RACE技术克隆获得Dmrt1基因cDNA全长,并利用生物信息学分析其结构及功能;利用半定量RT-PCR技术检测胡子鲇性腺(精巢/卵巢)、肌肉、肠、肝脏、心脏、头肾、鳃丝、脑和眼等10种组织以及Ⅱ—Ⅴ期精巢中Dmrt1基因表达。结果表明:胡子鲇Dmrt1基因cDNA全长为1417 bp,其中5′非编码区(5′-UTR)为35 bp,3′非编码区(3′-UTR)为516 bp,开放阅读框(ORF)包含864 bp,编码287个氨基酸(aa),预测所编码DMRT1为主要位于细胞核内的不稳定性亲水蛋白。氨基酸序列比对显示,胡子鲇DMRT1与已公布的非洲胡子鲇、蟾胡子鲇、黄颡鱼等鲇形目鱼类的相似性为83.3%—96.1%。胡子鲇DMRT1中具有DMRT基因家族共有的、保守性很高的DM结构域,此结构域具有典型的"C2H2C4"锌指结构,与上述鲇形目鱼类的相似性达100%,与斑马鱼、青鳉、虹鳟等鱼类的相似性为91.9%—97.3%,而与鸡、鼠、猪人等的相似性达80%以上。组织表达显示,胡子鲇Dmrt1基因仅在精巢中表达,且Ⅱ期精巢(即精子发生期)中Dmrt1基因表达量显著高于Ⅲ、Ⅳ和Ⅴ期精巢(P<0.05),而卵巢及其他8种组织中均无表达,表明Dmrt1是胡子鲇精巢特异性表达基因,可能与胡子鲇的雄性性别决定、精子发生及精巢发育密切相关。     

大口鲇微卫星标记在三个鲇形目鱼类种群间适用性研究

研究分析了12对大口鲇(Silurus meriaionalis)微卫星标记引物在兰州鲇(Silurus lanzhouensis)、鲇(Silurus asotus)及革胡子鲇(Clarias fuscus)各群体间通用性。结果表明,大口鲇微卫星标记引物除位点DQ223147、DQ223160扩增无特异性条带,位点DQ223149、DQ223159无多态性外,其余8对在这几种鲇形目鱼类中具有较高的通用性,每个位点等位基因数为2—15个不等;不同重复拷贝类别的位点以富含AC重复单元的等位基因数较多,多态性比较丰富。4个群体平均观测杂合度为0.7571,平均期望杂合度为0.6870,平均多态性信息含量0.6441,均为高度多态,说明这8个位点适用于鲇形目鱼类的遗传学研究。采用Nei’s遗传距离(D)绘制NJ系统发育树,4个群体聚成两大类,兰州鲇与鲇群体先聚类后和大口鲇聚为一大类,革胡子鲇聚为另一大类。8个有效微卫星位点中3个具有特异基因型的稀有等位基因位点(DQ223146、DQ223151与DQ223173),可区分4种鲇形目鱼类,作为其种质鉴定的标记位点。借用已有鲇形目鱼类遗传标记资源,增加同目鱼类遗传连锁图谱上遗传标记的密度,将对今后开展鲇形目鱼类种质资源保护及分子育种奠定坚实基础。       

中国胡子鲇属一新纪录及一稀有种的重新描述

胡子鲇属为广泛分布于非洲到南亚、东南亚及我国长江流域的淡水鱼类。朱元鼎教授(1931)在“中国鱼类索引”中总结我国有5种,尼柯尔斯(Nichols,1943)在“中国淡水鱼类简志”中归并为2种,张春霖教授(1960)在“中国鲇类志”中认为有3种。笔者参考中国科学院动物研究所保藏的标本及文献,认为有6种,     

我国引进鲇形目鱼类的初步研究

我国先后从国外引进钻形目的鱼类在国内饲养。据我们研究鉴定有：革胡子鲇，斑点胡子鲇，蟾胡子鲇，欧洲六须鲇，苏氏芒鲇，巨无齿芒，斑点叉尾Ｈｕｉ，长鳍叉尾Ｈｕｉ等９种，其中革胡子鲇和斑点叉尾Ｈｕｉ在我国已成为有发展前途的养殖对象。本文对引进我国饲养 鲇目撸类的种类，形态，养殖等方面进行了总结。     

桂南塘角鱼的生活习性及捕捉方法

塘角鱼即胡子鲇Clarias batrachus (Linnaeus)是一种肠短、骨少、肉多而味美的淡水野生鱼类。玉林地区把它做食欲不振病人的营养补品,还供外贸出口,经济价值比较高。 塘角鱼喜食水中的蛆、虫、水草等,对农作物有一定的益处。一般生长在水草茂盛的沟渠、稻田和沼泽中,并能耐干旱,在无水的泥地上,还能以每分钟1—5米的速度爬行,从一块田爬到另一块田或河沟中。     

胡子鲶与革胡子鲶的人工杂交及杂种F1养殖效果的初步研究

有关硬骨鱼类的种内、种间、属间、亚科间的杂交曾有不少的报道。从养殖效果看,有生产价值者虽仅限于少数种类,但在生产上往往能取得很大的经济效益和获得大幅度增产,如鲤鱼杂交,罗非鱼杂交等等。因而利用杂交方法改良养殖鱼类性状仍然是目前常用的手段之一。在1983—1985年,我们对原产埃及的革胡子鲶(Clarias lazera)与本地产胡子鲶(Clariasfuscus)进行了杂交研究,现作一简要报道。       

从细胞色素b基因序列变异分析中国鲇形目鱼类的系统发育

采用PCR技术获得中国鲇形目鱼类11科24属27个代表种类细胞色素b基因1138bp全序列,比较分析了来自北美洲、非洲的部分鲇形目鱼类同一基因序列,并选取脂鲤目、鲤形目和鲱形目鱼类作外类群,采用Bayesian方法和最大简约法(MP)构建分子系统树。结果表明：(1)鲇形目鱼类细胞色素b基因序列中,与脂鲤目、鲤形目以及鲱形目鱼类相比存在3bp的缺失;(2)鲇形目鱼类各科代表种类形成一单系群;(3)两种建树方法均支持铫科、粒鲇科和钝头鮠科形成一单系群;而胡子鲇科、刀鲇科、海鲇科、鮰科、长臀鮠科、鲢科、鲇科、棘脂鲿科、鲿科形成一大的单系群;但鳗鲇科的系统位置两种建树方法没有取得一致结果;而其中长臀鲍科与北美的鮰科形成姐妹群,胡子鲇、鮰科、鲇科、鲿科和鮡科是较明显的单系群。     

四种胡子鲇核型的比较研究

本文以鱼类肾细胞为材料,用空气干燥法制备染色体标本,对四种胡子鲇的核型进行了分析和比较。观察到这几种鱼的肾细胞中都存在不同程度的罗伯逊易位和其他染色体易位的现象。在蟾胡子鲇的核型中发现有粒状染色体的存在;在四种鱼中都发现可能是XY性染色体的异型染色体。结果还表明,斑点胡子鲇的核型可能由胡子鲇的核型通过染色体罗伯逊易位进化而来,而蟾胡子鲇的核型则是这四种鱼中最原始的一种。     

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.