毕赤酵母STE13基因敲除对GGH表达及其生物活性的影响

目的:重组毕赤酵母GS115/pPIC9K-GGH表达的人胰高血糖素样肽-1-人血清白蛋白融合蛋白[(GLP-1 A2G)2-HSA,GGH]的细胞活性测评结果显示生物活性较低,这可能与其表达过程中蛋白降解有一定关联.通过对毕赤酵母GS115 STE13基因的敲除,获得一株完整表达蛋白GGH的毕赤酵母宿主,并进一步提高其表达产物GGH的生物活性.方法:采用基于PCR技术介导的Cre-Loxp系统重组技术成功敲除宿主菌GS115的STE13基因,得到一株STE13缺陷型菌株GS115/D13,并通过细胞活性测评系统检测GS115/D13表达产物GGH的生物活性.结果:通过对STE13基因缺陷型菌株GS115/D13与出发菌株GS115/W发酵表达对比,显示GS115/D13菌株表达融合蛋白GGH生物活性有明显提升,且表达量提高了25.8％,两菌株生长无明显差异.结论:STE13基因的敲除成功缓解了GGH表达过程中的降解问题,并相对出发菌株GS115/W大幅度提高了蛋白生物活性.     

pBV220/hIL-4优化表达及其包涵体复性研究

旨在对人白细胞介素-4(hIL-4)上、下游序列进行优化设计,提高在原核系统中的表达量,并对表达的包涵体进行复性研究提高复性率.利用BioSun的RNA二级结构预测模块辅助设计hIL-4起始密码子(AuG)上、下游的序列,使局部二级结构的自由能满足高表达要求;根据pBV220栽体和原核系统的特点优化引物序列提高hIL-4原核表达量.优化hIL-4包涵体复性条件和方法,提高复性率和生物活性.结果显示,成功构建了pBV220/hIL-4高效表达栽体,原核表达的重组人IL-4占细茵总蛋白的35%以上,明显高于优化前表达量;经过复性研究hIL-4包涵体复性率可达到15%以上,生物活性鉴定发现,纯化的hhIL-4蛋白的比活等同或高于国外同类产品.影响原核表达的条件较多,对表达序列的优化设计可以大大提高蛋白的表达量.针对人IL-4基因序列的优化设计提高了人IL-4基因的表达,复性方法的改良提高了复性率和生物活性.     

OSF1在毕赤酵母菌中的分泌表达及其生物活性

为了研究人成骨细胞刺激因子(Human osteoblast-stimulating factor,OSF-1)的生物学活性,构建OSF-1高效毕赤酵母表达菌株并表达纯化具有生物活性的OSF-1。首先通过全基因人工合成的方法合成人osf-1基因,并克隆至毕赤酵母分泌表达载体pPIC9K,构建重组表达质粒pPIC9K/osf-1,线性化后电转化酵母宿主菌GS115,构建P.pastoris GS115/pPIC9K/osf-1,经MD、G418-YPD平板和PCR法筛选,获得多拷贝转化子。阳性表达菌株在25℃,经1%的甲醇诱导表达96 h,重组蛋白的表达量达到最大。经SDS-PAGE电泳分析所表达的重组蛋白约为18 kDa,与人成骨细胞刺激因子相符。表达上清经SP-Sephadex C-50离子交换层析进行纯化,得到纯度达98%以上的OSF-1。Western blotting鉴定该蛋白对人成骨细胞刺激因子抗体具有良好的抗原性。生物活性测定表明提纯的OSF-1能促进鼠成骨细胞MC3T3-E1的增殖和分化。利用重组毕赤酵母高效分泌表达了有生物活性的OSF-1,为进一步开展其抗骨质疏松活性研究及产业化开发奠定了基础。     

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。     

人干扰素和脑啡肽融合蛋白的表达和生物学活性

以INFα-m基因为模版,采用overlapping PCR技术构建甲硫氨酸脑啡肽干扰素表达质粒pBV220/Enk-/Met-INFα-m,转化大肠杆菌DH5α表达,产物以包涵体形式存在.包涵体经分离、变性、复性,然后经CM-Sepharose-FF、DEAE-Sepharose-FF离子交换层析和Sephacryal-HR100分子筛纯化,获得较纯的Enk-IFNα-m融合蛋白.生物活性检测表明,融合蛋白不仅具有干扰素的抗病毒、抗增殖、增强NK细胞功能的活性,而且具有脑啡肽的脑内镇痛作用.     

人重组白细胞介素12在CHO细胞中的表达

将人白细胞介素12（interleukin 12, IL-12）两条链p35及p40全长cDNA分别亚克隆至真核表达载体pcDNA3中,构建了pcDNA3/p35a,pcDNA3/p40a,pcDNA3/p35b,pcDNA3/p40b四种真核细胞重组表达质粒,利用磷酸钙共沉淀法转染中国苍鼠卵巢(CHO)细胞. 通过对阳性克隆的筛选鉴定,获得了稳定表达人IL-12的CHO细胞株,活性最高的一株表达量为105 U/ml.此细胞株经半年的传代培养,能够稳定地分泌IL-12.结果显示：IL-12在CHO细胞中的稳定表达受到重组质粒结构、DNA整合、mRNA转录、蛋白质翻译等多因素的影响,IL-12两个亚基在CHO细胞中的共同表达是产生有生物活性IL-12的基础.     

猪IL-18在乳酸乳球菌中的表达及其生物活性的检测

为了在乳酸乳球菌中分泌表达具有生物活性的猪IL-18蛋白,并检测其生物活性,故通过分离猪外周血单核淋巴细胞(PBMC),以其为模板,采用RT-PCR方法扩增猪白细胞介素18(pIL-18)基因,将目的基因与乳酸乳球菌表达载体pAMJ399进行连接,并电转化至乳酸乳球菌MG1363中,通过SDS-PAGE和Western blotting分析检测目的蛋白的表达,并通过脾淋巴细胞增殖试验和细胞病变抑制法对pIL-18的生物活性进行检测。Western blotting分析检测结果与生物活性检测结果显示,在重组菌pAMJ399-pIL18/MG1363的上清和菌体沉淀中19 kDa处均出现pIL-18的特异蛋白反应带,且分泌表达的pIL-18蛋白能明显促进猪脾淋巴细胞的增殖,并对病毒增殖有明显的抑制作用。以上结果表明pIL-18可在乳酸乳球菌分泌表达,且表达产物具有良好的生物活性。     

重组人αB干扰素在大肠杆菌中的克隆与高效表达

人αB干扰素(IFN-αB)是体内具有多种生物学功能的细胞调节因子,能抵御病毒感染和抑制肿瘤细胞生长,在临床上有广泛而重要的应用价值。IFN-α在治疗低度恶性淋巴瘤、慢性白血病、肝炎等方面显示良好的效果,资料表明IFN-αB抑制病毒作用较αD型干扰素强30倍。本文利用基因重组技术构建IFN-αB高效表达菌株E.coli XL-Blue/pBm,经酶(?)鉴定、DNA测序、SDS-PAGE、Western Blot及生物活性测定等分析鉴定,表明能特异性地表达具有生物活性的26 kD IFN-αB。表达水平达到23％(占总菌体蛋白比值),比活为1.0×10~6/mg,具有良好的应用前景。     

胰高血糖素在大肠杆菌中的分泌表达

报道了用基因工程方法构建含phoA(碱性磷酸酯酶)启动子、phoA信号肽与胰高血糖素基因的表达载体pAGluT.实验证明,转化了pAGluT的大肠杆菌(E.coli YK537)可高水平地分泌表达胰高血糖素,其表达量为80 mg/L.phoA表达系统分泌表达的胰高血糖素的物化性质与天然胰高血糖素相同,并具有相同的生物活性.这一结果不仅为基因工程生产胰高血糖素打下基础,亦为研制胰高血糖素的拮抗剂以及其他多肽的基因工程研究提供了新的思路.     

昆虫神经毒素LqhIT2的表达、抗血清制备及活性分析

根据毕赤酵母密码子偏爱性,不改变毒素蛋白质一级结构,设计合成了昆虫神经毒素LqhIT2基因,并分别克隆至大肠杆菌融合表达载体pPET30-a( )和毕赤酵母分泌表达载体pPIC9K.在IPTG的诱导下,神经毒素在大肠杆菌中融合表达,表达产物经镍亲和层析纯化后,用于免疫BALB/c小鼠,制备了特异性较高的抗血清,抗体滴度超过1:128 000.利用制备的抗血清,采用斑点杂交,筛选得到了较高水平分泌表达重组LqhIT2的酵母转化子,摇瓶条件下,毒素表达量约9 mg/L.大肠杆菌表达产物没有生物活性,酵母表达产物经注射蝗虫表现出杀虫活性.     

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.