细菌环二鸟苷酸介导的信号转导途径研究进展

环二鸟苷酸(c-di-GMP)是在细菌中广泛存在的第二信使分子,它介导的信号转导途径涉及调控细菌的运动、致病性、生物膜形成、细胞周期进程和有机溶剂耐受性等多种重要功能.该文主要从c-di-GMP的合成与降解、c-di-GMP的效应子及c-di-GMP的生理作用3方面对c-di-GMP介导的信号转导途径进行总结,并对该信号转导途径的研究前景进行了展望.     

Expression of the intact C<Subscript>4</Subscript> type<Emphasis Type="Italic">pepc</Emphasis> gene cloned from maize in transgenic winter wheat

Maize intact C4-pepc gene was amplified through LA-PCR and successfully sub-cloned into modified vector pGreen0029 to form a stable expression construct named as pBAC214 (12 kb), which contains CaMV 35S promoter driven bar gene as selection marker. Comparing the cloned DNA sequences (6.7 kb) with published maize C4-pepc gene (GenBank accession E17154) sequences, the identity of DNA sequence alignment is 98.96%. There are only 49 differences between these two intact DNA sequences, of which 13 occur in the region of promoter, 18 in introns, and 18 in exons. The homology of mRNA sequence alignment is 99.38%, and the putative amino acids sequence identity is 99.38%. There are only 15 differences between these two mRNA, and these differences bring 4 sites mutant on the putative amino acids of PEPC protein. Through biolistic bombardment of PDS1000/He system, expression vector pBAC214 has been transformed into winter wheat. Southern blotting results show that the intact C4-pepc gene has been integrated into genome of winter wheat. SDS-PAGE analysis of leaf soluble protein in transgenic wheat showed that the intact C4opepc gene was well transcribed, spliced and translated as in maize. The enzyme activity of leaf PEPC in transgenic wheat has been detected. The activities of leaf PEPC increased over 3-5 times in some transgenic plants. The data of photosynthesis rate and transpiration rate of transgenic wheat flag leaves showed that the C4-pepc gene can increase the photosynthesis rate and transpiration rate of transgenic wheat.     

β淀粉样蛋白来源的扩散性配体对胞外信号调节激酶活性的影响

β淀粉样蛋白来源的扩散性配体降低细胞外信号调节激酶的磷酸化水平,免疫印迹结果显示在培养的海马神经元上,给予500 nmol/L的可溶性β淀粉样蛋白寡聚体,作用不同时间均降低了胞外信号调节激酶的磷酸化水平;可溶性β淀粉样蛋白寡聚体对细胞不同部位胞外信号调节激酶磷酸化水平影响不同,并且对细胞质、细胞膜、细胞核中胞外信号调节激酶磷酸化水平的影响在时间上呈现明显的差异;β淀粉样蛋白来源的扩散性配体通过突触外N-甲基-D-天冬氨酸受体影响胞外信号调节激酶信号通路,单独激活突触外的N-甲基-D-天冬氨酸受体或给予β淀粉样蛋白来源的扩散性配体后再激活突触外的N-甲基-D-天冬氨酸受体,胞外信号调节激酶的磷酸化水平均明显降低;水迷宫实验显示,转入淀粉样前体蛋白基因的小鼠要花更多时间找到目标平台,其海马胞外信号调节激酶磷酸化水平显著降低.     

血吸虫血红蛋白降解途径的重构及关键酶蛋白保守结构域的分析

利用生物信息学方法,以疟原虫的血红蛋白降解途径为基础,成功地构建出了日本血吸虫和曼氏血吸虫的血红蛋白降解途径,并对降解途径上的关键酶蛋白的保守结构域进行了序列及结构分析。预测得到的血吸虫血红蛋白降解酶保守结构域,与疟原虫相比,在序列上催化位点高度保守,在结构上空间相对位置较一致,为研究血吸虫血红蛋白降解酶,及其与底物或...     

复杂网络分析激酶底物信号传递机制

为了研究信号从激酶到达底物蛋白质后的传递机制,本文将磷酸化和蛋白质相互作用结合构建网络,利用复杂网络理论对该网络进行分析.结果发现,底物中存在的社区结构不会只传递特定激酶组的信号,影响网络稳定性的关键节点大多参与肿瘤发生相关的信号途径.     

Aerosol oxalate and its implication to haze pollution in Shanghai, China

A total of 238 samples of PM2.5and TSP were analyzed to study the characteristics,sources,and formation pathways of aerosol oxalate in Shanghai in four seasons of 2007.The concentrations of oxalate were0.07–0.41 lg/m3in PM2.5and 0.10–0.48 lg/m3in TSP,respectively.Oxalate displayed a seasonal variation of autumn[summer[winter[spring in both PM2.5and TSP and was dominantly present in PM2.5in all samples.Correlation between oxalate and K?and high ratio of oxalate/K?suggested that biomass burning was a secondary source of aerosol oxalate in Shanghai,in addition to urban VOCs sources(vehicular and industrial emissions),especially in autumn.Secondary formation accounted for the majority of aerosol oxalate in Shanghai,which was supported by the high correlation of oxalate with nssSO42-,K?and NO3-,proceeding from different mechanisms.Relatively high ambient RH together with high cloud cover was found benefiting the secondary formation of aerosol oxalate.The in-cloud process(aqueous-phase oxidation)was proposed to be likely the major formation pathway of aerosol oxalate in Shanghai,which was supported by the high correlation of oxalate with nss-SO42-and K?,dominant residence of oxalate in droplet mode and result of favorable meteorological condition analysis.High correlation of oxalate and NO3-reflected the OH radical involved oxidation chemistry of the two species in the atmosphere and also suggested that gas-particle surface reactions and the evaporation–condensation process were both possible secondary formation pathways of aerosol oxalate in coarser particle mode([1.0 lm).As a major water-soluble organic compound in aerosols,concentration of oxalate showed a distinct negative correlation to the atmospheric visibility,which implied that aerosol organic compounds could play an important role in haze pollution as well as in air quality in Shanghai.     

基于NFAT信号通路的抗LAG3抗体8F-6生物活性检测

淋巴细胞活化基因3（LAG3）在T细胞活化和增殖过程中起负调控作用,通过单克隆抗体封闭LAG3分子可以增强T细胞对肿瘤的杀伤力,因此开发抗LAG3抗体的生物活性检测平台对免疫治疗具有重要意义。前期利用杂交瘤融合及抗体人源化改造技术,得到了一株全人源化的抗LAG3单克隆抗体8F-6,并基于活化T细胞核因子（NFAT）信号通路构建了Jurkat-NFAT-Luc2-LAG3和Jurkat-NFAT-Luc2-LAG3-CD3zeta细胞。本文利用所构建的细胞,通过酶联免疫吸附测定法（ELISA）和流式细胞技术对抗体8F-6进行亲和力及阻断效果检测。结果表明,抗体8F-6与LAG3分子具有良好的亲和力,可以阻断主要组织相容性复合体II （MHC II）分子与LAG3分子的结合;在报告细胞检测平台中,抗体8F-6在CHO-K1-FCGRIA细胞的协助下可以激活Jurkat-NFAT-Luc2-LAG3-CD3zeta细胞;在Daudi/Raji细胞、人金黄色葡萄球菌肠毒素E （SEE）和Jurkat-NFAT-Luc2-LAG3细胞的反应体系中,相比于对照抗体IgG1,抗体8F-6可以明显提高Jurkat-NFAT-Luc2-LAG3细胞的激活效果。     

H-蛋白中Asp-68和Tyr-70定向突变对甘氨酸裂解酶系整体酶活的调控

还原甘氨酸途径被认为是最有前景的C1（one carbon）合成途径,其核心酶系是甘氨酸裂解酶系。在前期研究中,我们在甘氨酸裂解酶系H-蛋白“解开自保护”过程的研究中初步锁定了H-蛋白空腔内的潜在关键氨基酸残基为Ser-67、Asp-68和Tyr-70,并且证明Ser-67位点对甘氨酸酶系的整体酶活有重要影响。本文对H-蛋白的Asp-68和Tyr-70位点进行了侧链带正电突变（H-D68K、H-D68H、H-D68R和H-Y70K、H-Y70H、H-Y70R突变体）,以及侧链非极性突变（H-D68G、H-D68V、H-D68M、H-D68L和H-Y70G、H-Y70V、H-Y70M、H-Y70L突变体）,并测定了各突变体在甘氨酸裂解方向上的酶活。结果发现,Asp-68位带正电突变倾向降低甘氨酸酶系的整体酶活,Asp-68位非极性突变、Tyr-70位带正电突变及非极性突变在总体上倾向于维持或提升整体酶活。其中,相对野生型H-蛋白,H-D68R突变体的酶活下降了90.2%,H-Y70R、H-D68G和H-Y70L突变体的酶活分别提高了75.6%、53.6%和146%。硫辛酰胺与H-蛋白空腔内的氨基酸相互作用的分析结果表明,甘氨酸裂解酶系整体酶活的变化是由于H-蛋白的68和70位残基的突变阻碍或促进硫辛酰胺的释放。     

脱氢枞胺-取代水杨醛Schiff碱的电喷雾串联质谱研究

 采用电喷雾电离串联质谱技术对7种最新合成的脱氢枞胺-取代水杨醛Schiff碱(DASSSB)样品进行了研究。结果显示,这些化合物的ESI-MS/MS裂解方式与它们分子中水杨醛苯环上取代基的性质和位置有关：当水杨醛苯环上4位连接供电子取代基时,分子以C=N双键断裂为主,生成 ［M+H-283］⁺ 碎片离子;当水杨醛苯环上5位连接吸电子取代基时,分子以C=N双键β位的C-C键发生断裂为主,生成 ［M+H-254］⁺ 碎片离子。DASSSB二级质谱产生的特征子离子可作为对此类化合物进行定性定量分析的依据。     

暗发酵制氢代谢途径研究进展

氢能因具备高热值、燃烧产物无污染、原料来源广泛等优点成为最具潜力的新能源之一。暗发酵因不受光照限制,产氢能力强,并可以解决环境污染问题而成为研究的热点。该文主要综述了暗发酵制氢的代谢途径及其研究进展,重点阐述了产氢菌株关键酶或基因改造的最新研究成果,并对其未来的应用进行了展望。