热预处理对细胞分裂效率的影响

以发酵酵母为研究对象，采用超声波空蚀和高压均质方法对细胞进行机械细胞分裂，研究了热预处理对微生物细胞分裂效率的作用。结果表明：酵母悬浮液的温度经热预处理从室温（22±1）℃上升到40-50℃时，达到相同程度的细胞分裂效率所需的能量降低了；当酵母悬浮液的温度经热预处理上升到50℃时，蛋白质浓度达到最大值，蛋白质发生变质的热预处理温度≥52℃。     

酵母耐高温分子机制的研究进展

耐高温是酵母在工业生产中的重要特性之一.近年来,人们对耐高温酵母的应用研究日益重视并取得较大的进展,但其耐高温分子机制尚未明确.目前的研究结果表明,酵母耐高温机制涉及代谢网络调控、信号转导途径及多基因/蛋白共同作用等方面.本文从代谢途径、基因表达、酶活特性和蛋白质相互作用等4个方面综述当前酵母耐高温分子机制的研究进展,...     

茅台酒曲中产淀粉酶细菌分离及性质

从茅台酒曲中分离出产α淀粉酶优良菌株,经鉴定为芽孢杆菌属。在这些菌株中,所产α-淀粉酶以中温型为主,最适宜温度在50~60℃之间,也分离到一株最适宜温度为80℃高温型酶的菌株。同时研究了发酵培养基中碳氮源比对一株芽孢杆菌酶活力的影响及酶活力与培养时间的关系,结果表明,当碳氮比为9∶4 5时酶活力较高,酶活力在生长周期稳定期后期到死亡期达到最高。     

芽殖酵母细胞周期过程不同时期的定量观测

在芽殖酵母中构建CDC10-mCherry和SPC42-mCherry荧光蛋白, 作为酵母细胞周期不同时期的报告系统。根据酵母细胞中芽环(CDC10-mCherry)的产生和消失以及纺锤体极体(SPC42-mCherry)的复制和分离,可以测量细胞周期中 G1期、S期、Early M期和Late M期的时间长度。在此报告系统的基础上, 分别构建S期细胞周期蛋白CLB5-GFP和M 期细胞周期蛋白CLB2-GFP菌株, 实现单细胞观测, 检验报告系统工作的稳定性和准确性。该报告系统可作为研究酵母细胞周期不同时期时间长度等定量生物学问题的背景菌株。     

Inhibitory effect of the adenovirus type 5 E1A protein expressed in the yeast system of the human tumor cell growth

Adenovirus 5 type E1A as a tumor suppressor gene can inhibit tumor growth and enhance the censitivity of chemotherapy and radiotherapy.E1A have the ability to integrate into the host genome,resulting in long-time expres-sion that induces Rb gene inactivation and animal cells im-mortalization.This prompted us to select the E1A protein for treatment of cancer in order to overcome the limitations of E1A gene therapy.Thus,we firstly comstructed E1A eu-caryotic expression vector (pPIC9/E1A),transformated the pichia pastoris yeast cells(GS115) and screened the high-expressing recombinant strains.The positive yeast strains were cultured in the shake flask,and induced for 3d.The crude E1A protein was purified using two steps of col-umu chromatography on HiTrap Q and HiTrap SP.The pu-rified E1A protein was identified by SDS-PAGE and Western blot.E1A protein was mostly located at cellular unclear when Cheriot delivered E1A protein into cells.The analysis in vitro indicated that the E1A protein arrested LN686 cell cycle at G2/M phase,and significantly inhibited the growth of LN686 tumor cells.The current studies firstly provided an experimental basis to further develop E1A protein for tumor treatment.     

Recent observations on the structure and the properties of yeast NMN adenylyltransferase

Summary A homogeneous preparation of yeast NMN adenylyltransferase (EC 2.7.7.1) showed microheterogeneity, which was revealed by FPLC (Fast Protein Liquid Chromatography) ion exchange chromatography. The resolved components have been characterized with respect to electrophoretic behavior and adenine content. The results led to a hypothesis about a possible role of poly(ADP-ribosylation) in modulating the enzyme activity.     

Screening of the interacting proteins with NifA in <Emphasis Type="Italic">Azospirillum brasilense</Emphasis> Sp7 by the yeast two-hybrid system

NifA in AzospiriUum brasilense plays a key role in regulating the synthesis and activity of nitrogenase in response to ammonia and oxygen available. In this work we used the yeast two-hybrid system to identify the proteins that interact with NifA. The nifA gene was fused to the yeast two-hybrid vector pGBD-C2, and three A. brasilense Sp7 genomic libraries for use in yeast two-hybrid studies were constructed. Screening of the libraries identified four clones encoding proteins that interact with NifA. The confirmation of the interactions of each gene product of the four clones and NifA were carried out by exchanging the vectors for nifA and the four clones and by mutageneses of the four clones with shift reading frame experiments in yeast two-hybrid studies. DNA sequence analyses showed that two clones encode proteins containing PAS domains that play an important role in signal transduction. One clone has high similarity with the fhuE gene of Escherichia coli, whose gene product is involved in iron uptake and transportation, and the other clone encodes an unknown protein.     

利用酵母双杂交系统筛选IrrE相互作用蛋白

本研究通过酵母双杂交技术,构建了IrrE蛋白为诱饵载体,从拟南芥cDNA文库中筛选与IrrE诱饵蛋白相互作用的功能蛋白.研究结果表明,在所获得的阳性克隆中,发现了一个与拟南芥基因At1g01470所编码的蛋白有较高同源性的蛋白,即LEA14蛋白（晚期胚胎发育富集蛋白）,同源性高达98%.推测IrrE转录因子在提高植物耐盐性的过程中起了重要作用.