大肠杆菌表达Trx-rPA融合蛋白的复性纯化

大肠杆菌高密度发酵以包涵体形式表达融合蛋白Trx-rPA,表达量22%。包涵体蛋白洗涤后经金属螯合层析纯化,纯度达80%以上。经胱氨酸衍生,以脉冲加样形式复性,复性率可高达30%。经ETI-Sepharose纯化,复性的融合蛋白生物活性可达3.5×105IU/mgPr.。融合蛋白可被rEK酶切释放rPA,酶切效率达85%以上。酶切液经IDA-Sepharose和SP-Sepharose层析纯化,rPA纯度达98%以上,生物活性50万IU/mgPr.。1L发酵液经分离、复性及纯化后,可得高纯度rPA300mg以上。     

大肠杆菌表达的重组白细胞介素-2的初步纯化

本文对大肠杆菌表达产生的重组白细胞介素-2进行了纯化研究。通过比较两种方法制备的rIL-2包含体的纯度,发现用4mol/L脲溶解可溶性细菌蛋白后可使rIL-2包含体纯度达70％;在高浓度变性剂条件下进行凝胶过滤,解决了rIL-2易聚合的问题;结合透析,利用空气氧化形成高活性氧化型rIL-2;经SephadexG-100凝胶过滤,DEAE离子交换等步骤纯化,得到了均一性rIL-2,纯度达98％,比活达4.3×10~6u/mg蛋白,得率为30.8％。     

大鼠心肌营养素-1基因在大肠杆菌中的表达与初步纯化

为了实现心肌营养素 - 1 ( CT- 1 )的高效与可溶性表达 ,将 CT- 1基因分别插入到 3种大肠杆菌表达载体 p BV2 2 0、p GEX- 2 T和 p Trx FUS中 ,并实现了表达 ,全菌表达水平分别为 2 .6%、1 6%和 2 5 %。其中 ,CT- 1在 p Trx FUS表达载体中以包含体和可溶性两种方式表达 ,表达水平分别为2 0 .8%和 1 0 .7%。可溶性表达部分经过强阴离子交换和凝胶过滤两步纯化 ,纯度达 80 %以上     

重组人白细胞介素4的纯化及N端氨基酸序列分析

本文对重组人白细胞介素4高效表达克隆pBV220/hIL-4a的表达产物进行了纯化,升对纯化的人IL-4进行了N端氨基酸序列分析。人IL-4基因表达产物在大肠杆菌中以不溶性包涵体形式存在,经过超声破菌、包涵体抽提、复性浓缩、离子交換和凝胶过滤层析一系列纯化步骤,终产物纯度达98％以上,按蛋白总量计算回收率为14％,比活性达2×10~6单位/mg蛋白。通过测定纯化人IL-4的N端16个氮基酸序列,与由其DNA序列推导的氨基酸序列完全一致。本文为重组人IL-4的批量生产奠定了基础。     

人重组PSP及其生物活性研究

为了获得人重组 persephin( PSP)并研究其生物学活性 ,从人胎脑组织中提取总 RNA,以RT- PCR方法获取编码人 PSP成熟蛋白 c DNA.将人 PSP c DNA插入含 T7启动子的质粒 p ET-2 8a( + ) ,构建表达质粒 p ET- PSP,转化大肠杆菌 BL 2 1 ( DE3)获得表达菌株 BLPSP,经 IPTG诱导表达的 PSP形成包含体 .凝胶自动扫描分析表明 ,PSP表达量约占菌体总蛋白 2 0 %以上 .用Ni2 + - NTA树脂一步法纯化目的蛋白 ,纯度达 85%以上 .纯化和复性的 PSP蛋白能显著促进脊髓神经元的存活 .     

重组人TGF-β3的表达纯化及复性研究

利用大肠杆菌表达重组人转化生长因子β3(humantransformgrowthfactor,hTGFβ3),目的蛋白以包涵体形式表达。用8mol/L尿素溶解的包涵体蛋白,经CMSepharoselFastFlow柱和SphacrylS100分子筛可获得纯度达90%以上的rhTGF-β3单体。将单体蛋白加到复性缓冲液(1mol/LNaCl,0.5mol/LLArg,0.5mmol/LGSSG,30mmol/LCHAPS,20%(v/v)DMSO)进行复性后,再经DEAESepharoselFastFlow柱和SphacrylS100分子筛可分离得到纯度达94%的二聚体rhTGFβ3,纯化后的产量为720mg/L,纯化总回收率为47%。MTT法测活表明,该重组蛋白具刺激成纤维细胞Balb/c3T3生长的作用。     

重组人超氧化物歧化酶的基因克隆、表达及产物纯化研究

为了克隆人SOD-cDNA,构建表达载体,实现其在大肠杆菌中的高效稳定表达,通过抽提人肝组织总RNA,RT-PCR扩增人SOD cDNA,构建含rhSOD cDNA的表达质粒pLY-4/rhSOD,转化大肠杆菌JF1125进行表达研究。结果克隆到的rhSOD cDNA序列与文献报道一致,在宿主菌中获得高效表达,表达水平达68%以上;蛋白复性纯化工艺高效快速,rhSOD纯品纯度达98%以上,比活性达到2529u/mg;为用基因工程方法生产rhSOD打下基础。     

重组人IL-4大肠杆菌表达与纯化

根据大肠杆菌密码子偏爱性优化并合成人白细胞介素4基因,以pET30a( )为载体构建了重组表达质粒pET30a( )/rhIL-4,将重组质粒转化大肠杆菌BL21(DE3)感受态细胞,诱导表达并超声破菌检测重组蛋白的表达形式。采用5L发酵罐培养工程菌,发酵液OD600为0.6时诱导3.5h收集菌体,检测目的蛋白的表达量。收集的菌体经压榨破菌获得包涵体,通过包涵体变性、层析、透析复性等方法对rhIL-4进行纯化。采用人红细胞白血病细胞(TF-1)测定纯化的rhIL-4的生物活性。测序表明目的基因已插入载体pET30a( )中,重组蛋白以包涵体形式表达,单位体积重组蛋白的表达量达200mg/L发酵液,建立了对包涵体形式表达的rhIL-4纯化方法,最终得率为40mg/L发酵液,纯度大于98%,回收率为20%以上。免疫印迹法检测诱导表达的重组蛋白和纯化的蛋白为IL-4,N端氨基酸序列测定结果与理论相符,生物活性检测纯化的蛋白比活性达2.5×106AU/mg。这为rhIL-4进一步产业化研究建立了基础。     

应用单克隆抗体免疫亲和柱纯化干细胞因子

应用抗人干细胞生长因子(SCF)单克隆抗体,通过化学偶联方法制备成亲和层析柱,用于纯化大肠杆菌表达的可溶性重组人rh-SCF.结果表明,经亲和柱纯化的样品经SDS-PAGE电泳检测纯度达95%以上,计算蛋白回收率为23.4%,并且纯化后rh-SCF生物活性明显高于纯化前样品.     

重组人成骨蛋白-1的离子交换及分子排阻色谱法纯化及其复性研究

经发酵大量表达重组人成骨蛋白-1(rhOP-1)。SDS-PAGE发现rhOP-1表达量占细菌总蛋白的35%。菌体经裂解、洗涤后,用8mol/L尿素溶解包涵体,离心后提取目的蛋白。经离子交换色谱法对变性状态下的目的蛋白进行纯化,绝大部分杂蛋白被去除,目的蛋白纯度达93%以上。为进一步提高目的蛋白浓度,采用分子排阻色谱法对目的蛋白进行再次纯化,纯度达98%以上。利用降低尿素梯度的方法对纯化的蛋白进行复性,二聚体的含量在50%以上。Westernblot证明了复性后的目的蛋白以单体和有活性的二聚体的形式存在。     

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.