新型重组糖蛋白表达载体--盘基网柄菌

近年来,盘基网柄菌作为异源重组糖蛋白表达载体的研究受到了学术界的重视,已经有多种具有生物活性的复杂糖蛋白成功地得到了表达。通过对表达产物的研究发现,盘基网柄菌具有各种翻译后加工机制,例如磷酸化、酰基化及形成GPI(糖基磷脂酰基醇)锚点等,具有类似于高等动物的糖基化修饰能力。与哺乳动物细胞表达载体相比较,盘基网柄菌具有培养成本低廉、细胞生长迅速及易于大规模培养的优势。盘基网柄菌有可能发展成为一种有重要应用前景的糖蛋白表达载体系统。     

固定化米根霉生产L－乳酸的研究

开发了利用聚氨酯泡沫为载体固定化米根霉生产Ｌ－乳酸的新工艺。确定了固定化细胞发酵条件：葡萄糖浓度为５０ｇ／ｌ,载体立方体边长为４～８ｍｍ,载体量为２０ｃｍ３／７０ｍｌ培养基,固定化细胞制备培养时间为２４ｈ．利用固定化细胞发酵产酸速率是游离菌的３倍以上,对糖转化率达７７．７０％,与理论转化率相近。该固定化细胞应用在反复间歇发酵中可稳定１０批次以上。     

盘基网柄菌DJ-1蛋白的原核表达及抗体制备

盘基网柄菌(Dictyostelium discoideum)是研究神经退行性病变的模式生物,可用以研究帕金森病相关基因DJ-1的作用和致病机理.本研究设计特异性引物扩增了人类DJ-1的盘基网柄菌同源基因片段DAM,并利用酶切位点BamH Ⅰ和Hind Ⅲ将DAM插入质粒载体pQE-30产生重组载体pPROF696,序...     

盘基网柄菌肌动蛋白的生物信息学分析

盘基网柄菌Dictyostelium discoideum是目前黏菌中研究最清楚的模式生物,其捕食过程与肌动蛋白的多聚化密切相关。为探讨盘基网柄菌肌动蛋白的序列特征,本研究利用生物信息学方法分析了盘基网柄菌32条肌动蛋白的蛋白-蛋白相互作用(protein-protein interaction)和可能含有的保守基序。结果表明:盘基网柄菌32条肌动蛋白与其他蛋白存在一组复杂相互作用关系和5组比较简单的相互作用关系;利用MEME SUITE分别分析盘基网柄菌32条肌动蛋白序列的保守基序和与actin17呈最佳匹配的21种生物肌动蛋白的保守基序,结果共获得6个保守基序,即motif1,motif2,motif3,Motif1,Motif2,Motif3。其中motif1,Motif1,Motif3为本研究新发现的保守基序,这3个保守基序可定位于Profilin-actin-VASP202–244(PDB ID:3CHW)三维结构的重要位置。以上结果表明actin3,actin10,actin14,actin15,actin17,actin31可能为盘基网柄菌比较重要的肌动蛋白;motif1,Motif1,Motif3可能是盘基网柄菌肌动蛋白在进化中重要的保守基序。     

盘基网柄菌发育中的细胞粘附分子及其信号转导

在盘基网柄菌发育早期,DdCAD-1和csA调节了变形虫细胞间的粘着,调控该过程的机制类似于胚胎发育中上皮细胞层的闭合。完成网柄菌发育的一个必需分子是gpl50异嗜性粘附分子。盘基网柄菌β-连环蛋白同源物Aardvark(Aar)的缺乏使细胞间失去粘着连接,Aar也有信号转导功能,调控了前孢子细胞基因的表达。因此,细胞间的粘着是盘基网柄菌发育的一个重要组成部分,并与调控形态发生过程的信号转导有密切相互作用关系。     

盘基网柄菌中分化诱导因子信号与细胞命运决定

对盘基网柄菌发育过程中分化诱导因子(DIF)的作用及其机制进行了综述,包括DIF对盘基网柄菌前柄细胞、柄细胞分化的作用以及DIF的生物合成、DIF的诱导、降解失活、DIF对细胞命运和细胞比例的调节及其作用机制等。     

将盘基网柄菌用于本科细胞生物学综合性实验教学初探——电穿孔转化绿色荧光蛋白

盘基网柄菌(Dictyostelium discoideum)是一个应用广泛的模式生物,非常适合用来研究胞质分裂、细胞运动、吞噬作用、趋化性、趋电性、信号转导以及个体发育过程中的细胞分化。该实验主要介绍电穿孔技术转化绿色荧光蛋白标记肌动蛋白基因质粒(Lifeact-GFP)进入盘基网柄菌活细胞中,抗性筛选(潮霉素B)获得阳性克隆子,最后借助荧光显微镜观察绿色荧光蛋白标记的微丝在盘基网柄菌的分布情况。综合性实验训练可提高学生的学习兴趣和综合运用理论知识的能力,进而可培养学生的科学研究思维。     

微生物絮凝剂产生菌固定化条件的优化

采用多种固定化方法及载体,进行了微生物絮凝剂产生菌M09固定化方法及条件的研究,并对其所产絮凝剂在不同存储条件下絮凝活性的稳定性进行探讨。结果表明,选用粒径为0.5 cm×0.5 cm×0.5 cm的多孔聚氨酯泡沫为固定化载体,4 g/L的固液比,使用初始蔗糖浓度为2%,NaNO3为0.4%的培养基,28℃振荡培养60 h可获得较高活性的固定化细胞,发酵上清液能够保持较高的絮凝率。研究还发现,在室温条件下,利用此工艺所产高絮凝活性发酵液在含有菌体的反应器内自然静置,发酵液絮凝率仍可缓慢持续上升,维持较高水平达数日,具有较高的稳定性。     

利用固定化菌半连续生产微生物絮凝剂的研究

利用多孔聚酯泡沫为载体,进行了微生物絮凝剂产生菌的固定化条件优化和半连续生产絮凝剂的研究。研究发现,利用多孔聚酯可吸附固定XN1菌丝细胞,且能够较长时间保持高的活性。选择载体颗粒0.5cm×0.5 cm×0.5 cm,固液比为6 g/L,接种量105个孢子/mL培养基可达到较好的固定化和产絮凝剂效果。利用最佳固定化条件进行絮凝剂的摇瓶半连续生产实验发现,在最佳条件下,固定化XN1菌产絮凝剂可连续达12批次,且絮凝活性均在90%以上,说明利用多孔聚酯泡沫颗粒作为固定化载体,连续生产絮凝剂的方法是可行的。且和游离菌生产絮凝剂相比,生产效率可提高77.78%。     

芸豆植物凝集素对细胞生长和增殖的影响

目的:以乳酸菌及盘基网柄菌为代表研究芸豆PHA对其增殖的影响。方法:采用纸片扩散法观察芸豆PHA对乳酸菌增殖的影响;采用液体振荡和贴壁培养观察芸豆PHA对盘基网柄菌生长增殖的影响。结果:1)乳酸菌培养12 h,1 mg/ml组滤纸片周围出现大的菌落,继续培养各浓度含芸豆PHA滤纸片周围均出现生长圈,对照组无生长圈;2)振荡培养24h时,低剂量各芸豆PHA组细胞密度比值最大,1mg/ml组达2.25,高于2.5mg/ml组细胞密度不随时间而增加,5.0和10 mg/ml组贴壁培养12h,盘基网柄菌不运动为死亡状态。结论:芸豆PHA对不同种类生物的生长增殖具有广泛的调节作用,其作用呈明显的剂量-效果关系。     

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.