蒙古冰草Actin基因片段的克隆及序列分析

旨在利用同源序列法分离蒙古冰草(Agropyron mongolicum Keng)Actin基因同源片段,为研究其他基因在蒙古冰草中的表达和调控提供内标参照.根据禾本科植物小麦Actin基因(AB181991)的保守序列设计2对引物A4和A5,采用RT-PCR扩增蒙古冰草的Actin基因片段,分别得到656 bp和848 bp的片段,使用DNAman和DNAuser等分子生物学软件进行序列分析,将2个片段的重复序列合并后获得一段长度为962 bp的基因片段,编码237个氨基酸,将克隆的Actin基因片段命名为MwACT.该序列与其它植物Actin基因核苷酸序列的同源性均在80%以上,其中与小麦、大麦的同源性达到94%;与氨基酸序列的同源性均在90%以上.     

采用苯酚羟化酶基因特异引物检测苯酚降解菌

根据苯酚羟化酶基因高度保守序列设计了一对该基因的特异PCR引物。采用该特异引物从苯酚降解菌醋酸钙不动杆菌 (Acinetobactercalcoaceticus)PHEA 2的总DNA中扩增到唯一一条大小为 684bp的片段。该DNA片段与已知的A .calcoaceticusNCIB82 50的苯酚羟化酶基因具有高度的同源性 ,其核苷酸序列的同源性为 84% ,推导的氨基酸序列的同源性为 98%。对苯酚和非苯酚降解菌株的PCR扩增结果表明 :所有苯酚降解菌均能扩增出 684bp的特征片段 ,而非苯酚降解菌则无PCR条带。对炼焦废水中的细菌群落进行PCR扩增和生化特性检测表明 :显示 684bp特征片段的菌株均具有苯酚降解特性。上述结果表明 ,利用苯酚羟化酶基因的特异引物可对环境中的苯酚降解菌株进行准确快速的PCR检测。     

油桐尺蠖核型多角体病毒DNA聚合酶基因的克隆和序列分析

用PCR方法从油桐尺蠖核型多角体病毒(BusuNPV)中扩增出DNA聚合酶基因片段,经pGEM-T载体克隆到大肠杆菌DH5α菌株中。经自动序列分析仪测出DNA聚合酶基因2379bp长的核苷酸序列,推导出793的氨基酸序列。氨基酸同源性比较显示,BusuNPV与HzSNPV的同源性最高,达57%;与OpMNPV的同源性最低,为39.6%。     

油桐尺蠖核型多角体病毒DNA聚合酶基因的克隆和序列分析

用PCR方法从油桐尺蠖核型多角体病毒 (BusuNPV)中扩增出DNA聚合酶基因片段 ,经pGEM T载体克隆到大肠杆菌DH5α菌株中。经自动序列分析仪测出DNA聚合酶基因 2 379bp长的核苷酸序列 ,推导出 793的氨基酸序列。氨基酸同源性比较显示 ,BusuNPV与HzSNPV的同源性最高 ,达 57% ;与OpMNPV的同源性最低 ,为 39.6 %。     

乙肝病毒突变核心蛋白基因的克隆及序列分析

目的克隆发生长片段缺失的乙肝病毒核心蛋白基因（HBV-C）,并对其进行DNA序列和蛋白质结构分析。方法通过PCR从1株乙型肝炎病毒中扩增得到发生长片段缺失的HBV-C基因,利用TA克隆将PCR产物克隆人pUCm—T载体并进行测序、同源性比较和蛋白质结构分析。结果PCR扩增出的HBV-C基因经序列分析表明长度为454bp,其核苷酸序列缺失了220—317bp之间的98个碱基,造成从74个氨基酸起发生移码突变。结论成功克隆发生长片段缺失的HBV-C基因,为表达及功能研究奠定了基础。     

雄牛特异的SRY同源序列的扩增和分析

利用人、兔、鼠SRY序列设计引物,应用PCR扩增牛的SRY序列,获得200bp的雄牛特异的扩增片段。克隆该扩增片段,获得重组质粒pCH21,进行序列分析,并与人、兔和鼠SRY的对应区域比较,具有高度同源性。用pCH21 DNA作探针与牛的基因组DNA酶切图谱杂交,显示了雄牛特异的I．7kb的杂交带。分析200bp的PCR扩增片段是牛的SRY基因片段。用同一对引物扩增人和山羊的DNA样品,也获得雄性特异的200bp的扩增片段。     

溶藻弧菌HY9901 AcrA基因克隆与序列分析

Touchdown PCR扩增溶藻弧菌HY9901 AcrA基因部分序列,得一460bp片段,再以反向PCR和巢式PCR联合扩增其侧翼序列,拼接得一由1101 nt组成,共编码366 aa的完整基因.该基因演绎的氨基酸序列与几种弧菌的同源性都比较高,与创伤弧菌YJ016、副溶血弧菌RIMD 2210633、灿烂弧菌12B01、霍乱弧菌O1 N16961同源性分别为76%、73%、71%和70%.     

利用Taq DNA聚合酶直接从双链RNA模板中扩增靶序列

利用Taq DNA聚合酶既具有DNA聚合酶活性义具有反转录酶活性的特点,探索了在Taq DNA聚合酶单独作用下以双链RNA为模板进行PCR反应的条件。结果表明靶序列长度为277 bp、369 bp、987 bp时,均可直接进行PCR扩增;短片段序列扩增的退火温度在47．0℃、47．9℃、50．2℃、52．6℃、54．9℃、56．7℃条件下,均可有效扩增,而长片段序列扩增的退火温度在50．2℃、52．6℃、54．9℃、56．7℃条件下,也可扩增出相应的靶序列。这一结果提示利用Taq DNA聚合酶可以dsRNA为模板直接扩增目的片段,尤其是短片段的扩增。     

一个巴西橡胶树钙调素基因假基因的识别

以巴西橡胶树(Hevea brasiliensis)基因组DNA为模板,根据胶乳钙调素基因HbCaM序列设计引物,利用PCR方法克隆获得了1 319 bp和447 bp的两个DNA片段.序列分析表明,1 319 bp的DNA长片段为胶乳钙调素基因HbCaM的DNA片段,含有两个外显子(77 bp和373 bp)和1个内含子(869 bp),包含了HbCaM cDNA编码区447 bp的全部序列;447 bp的DNA小片段与HbCaM cDNA核苷酸序列同源性高达98%,ORF分析发现,位于406?bp处的碱基C突变为T,即三联体密码CAG突变为终止子TAG使翻译提前终止,其余5个差异碱基都不影响或改变正常的翻译.推测此447 bp的DNA片段为巴西橡胶树钙调素HbCaM基因的假基因,命名为HbCaMP1.     

PCR-mtDNA技术鉴别检测不同动物肌肉组织和饲料中鸭源性成分

以鸭肌肉组织DNA为模板,利用PCR-mtDNA技术成功克隆出了鸭mtDNA COIII基因(GenBank Accession No.DQ655706).对所克隆的序列分析表明.其序列包括鸭细胞色素C氧化酶III(COIII)基因全序列784 bp,通过同源性分析可知,动物的线粒体DNA COIII基因是相对保守的,利用此特性设计PCR-mtDNA方法鉴别检测鸭源性成分的特异性引物;以各种动物肌肉组织及饲料DNA为模板进行PCR扩增、经反复验证筛选出只能扩增出鸭DNA的目的片段,而不能扩增出其他动物DNA片段的特异性强、稳定性好的引物P3、P4;利用此引物PCR扩增鸭DNA的特异性片段为226 bp,对PCR产物进行测序分析可知与已克隆的鸭mtDNA COIII基因同源性达到100%,证明了所筛选引物的准确性.通过对不同含量的DNA模板溶液进行PCR扩增的方法,对筛选出的特异性引物P3、P4进行灵敏度试验,结果分析表明灵敏度约为0.001%,证明该PCR方法具有特异性强、灵敏度高的特点,完全可作为鉴别不同动物肌肉组织和饲料中鸭源性成分的方法.     

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.