鸡肝二氢叶酸还原酶在盐酸胍溶液中构象的序变与激活

用蛋白质内源荧光、疏水荧光探针TNS及蛋白酶K限制性酶解等方法研究了二氢叶酸还原酶在盐酸胍变性过程中的构象变化及动力学,并与活力变化进行了比较.TNS可以监测到与激活同步的构象变化;盐酸胍浓度大于0.75mol/L时,二氢叶酸还原酶被蛋白酶K水解速度增大;当盐酸胍浓度大于1.2mol/L时,才能监测到酶分子整体构象的变化.以上结果表明二氢叶酸还原酶在盐酸胍溶液中的变性并不符合标准的二态模型,而是先经历构象逐步松散的序变过程,然后发生协同的构象伸展.二氢叶酸还原酶在低浓度盐酸胍溶液中的激活是由于酶活性部位构象的微小变化引起的.酶活性部位构象的变化虽然降低了酶与废物的结合能力,但加快了酶促反应限速步骤,即底物解离速度而使酶活力升高.     

Low temperature induces oocytes p34^cdc2 synthesis and accumulation—the acquisition of competence to resume meiosis in toad oocytes

Full grown oocytes derived from Bufo Bufo gargarizans rearing at high temperature environment (24℃), never underwent GVBD after progesterone treatment.No p34^cdc2 Hl kinase activity was detected in the oocytes after progesterone stimulation or OA microinjection;Western blotting analysis showed that the level of p34^cdc2 and p33 in the oocytes are significantly lower than those in the oocytes derived from the hibernating toads (below 10℃).^35S-Met incorporation analysis showed that when the oocytes were incubated at 6℃,synthesis of about thirty defferent polypeptides was promoted or induced,including p34^cdc2 and some other p13^suc1-binding proteins.All these results indicated that a low temperature environment is essential for the oocytes of Bufo Bufo gargarizans to express and stord some cell cycle drivers and its regulators,and to gain the maturation competence.These results will also provide a nwe clue for explaining the molecular mechanisms why gametogenesis of some organisms depends on a relative low temperature and how to maintain the geographical distribution of some animals.     

HOG1抑制剂调节球头三型孢菌多元醇生产及机理

目的:采用HOG1抑制剂对球头三型孢菌产多元醇进行调控。方法:向培养基中加入SB239063、SB202190和SB203580三种抑制剂进行发酵实验,比较三种抑制剂对发酵的影响。结果:实验结果表明SB239063可以降低球头三型孢菌细胞内胞浆3-磷酸甘油脱氢酶(ct GPD)的酶活,提高赤藓糖还原酶(ER)的酶活。此外对HOG1和Phospho-HOG1的Western blot结果分析显示,SB239063还会抑制球头三型孢菌细胞内HOG1的脱磷酸化。最终添加10μmol/L SB239063使发酵120 h后的多元醇产物中甘油产量下降20.57%,赤藓糖醇产量提高31.16%,底物转化率提高24.73%。结论:SB239063可以降低球头三型孢菌产甘油的能力,提高赤藓糖醇的产量。     

脑外伤后ERK信号通路调节AQP4及其锚定蛋白DG的表达

脑外伤是青年人最主要的致死与致残疾病。脑水肿是脑外伤的严重并发症,其形成与脑内最主要的水通道蛋白4（aquaporin4, AQP4）关系密切。AQP4对水的转运与其在星形胶质细胞胞膜上的极性分布有关。肌营养不良-肌萎缩蛋白复合物（dystrophin-dystroglycan complex, DDC）可能与AQP4的锚定及极性分布有关。肌萎缩蛋白（dystroglycan, DG）是该复合物的核心成员,但其对AQP4锚定及极性表达的作用目前并不清楚。脑外伤后,AQP4的表达改变是否与DG有关,其二者表达变化的调控机制均不清楚。为了揭示以上科学问题,为临床治疗脑外伤后脑水肿提供理论依据,分别进行在体、离体及离体干扰实验。研究发现脑外伤后,AQP4、α-DG、β-DG的表达,于6 h增至峰值,后逐渐减弱,于24 h降至最低,48 h再次表达上调。在此过程中,其表达变化规律虽基本一致,但确实存在不一致的现象。排除其他因素干扰,在星形胶质细胞划伤后,DG与AQP4及p-ERK的表达改变完全一致;抑制及激活ERK信号通路后,分别导致DG与AQP4的表达下调及上调。以上结果证实,脑外伤后,DG参与AQP4在星形胶质细胞的锚定,但并非AQP4极性表达的专属锚定蛋白质;机械损伤后,早期ERK信号通路激活,并上调DG及AQP4的表达。     

烟草NtFtsZ2-1基因参与叶绿体分裂和扩大的调节

叶绿体虽然是植物细胞内一种极其重要的细胞器,但其分裂的分子机制尚不很清楚。已经证明FtsZ蛋白作为真核细胞分裂装置的一个关键成分,参与叶绿体的分裂过程。烟草的FtsZ基因属于2个不同的家族,在对NtFtsZ1家族成员研究的基础上,用正义和反义表达技术研究了NtFtsZ2家族成员NtFtsZ2-1基因在转基因烟草中的功能。显微分析结果表明NtFtsZ2-1基因的表达水平异常增强或减弱都会严重干扰叶绿体的正常分裂过程,导致叶绿体在形态和数目上的异常（体积明显增大,数目显著减少）,而单个叶肉细胞中叶绿体的总表面积在正反义转基因烟草和野生型烟草之间保持了相对稳定,没有发生明显的变化。同时还证明NtFtsZ2-1基因表达的变化对叶绿素含量和叶绿体的光合作用能力没有直接的影响。据此我们认为NtFtsZ2-1基因参与叶绿体的分裂和体积的扩大,其表达水平的波动会改变植物中叶绿体的数目和大小,而且在叶绿体的数目与体积之间可能存在一种补偿机制,保证叶绿体能最大限度地吸收光能,从而使光合作用得以正常进行。     

RT-SHIV rt基因单拷贝PCR扩增方法的建立及初步应用

目的建立RT-SHIV病毒全长rt基因单拷贝PCR扩增方法,用于HIV-1 rt基因体内遗传与变异研究。方法 Oligo软件设计RT-SHIV rt基因特异性扩增引物,梯度稀释方法进行特异性和灵敏度筛选,进而优化退火温度和PCR反应最佳循环数等条件,建立rt基因PCR扩增方法;在此基础上将模板进行有限稀释,摸索rt基因单拷贝PCR扩增条件;使用该方法扩增感染猴体内RT-SHIV病毒rt基因,BioEdit软件进行基因序列分析。结果筛选得到一组巢式PCR引物,成功建立了RT-SHIV rt基因PCR扩增方法;当模板浓度为100 copies/μL时,扩增产物为单拷贝序列;测序结果显示RT-SHIV感染猴d266和d294血浆样本分别存在1处和6处氨基酸突变。结论本研究建立的全长rt基因单拷贝PCR扩增方法特异性好、灵敏度高、重复性强,可以应用于各类RT-SHIV病毒的全长rt基因分析。     

荷木树干CO_2释放通量与木质部液流和CO_2浓度的关系

采用红外气体分析仪,于2008年10月17-19日连续3个昼夜原位监测了荷木的树干CO_2释放通量、树干温度、木质部液流密度和CO_2浓度.结果表明:树干CO_2释放通量(EA)日变化呈S形曲线,不同径级间差异显著.EA与树干温度呈显著幂函数关系(0.24

Abstract：

By using a Li-820 infra-red CO_2 gas analyzer, an in situ measurement of Schima super-ba stem CO_2 efflux was conducted for three consecutive days from 17 to 19 October 2008. In the meantime, the stem temperature, xylem sap efflux density, and xylem CO_2 concentration were measured. The stem CO_2 efflux had a diurnal variation of "S" pattern, and differed significantly with stem diameter. There was a significant exponential relationship between stem CO_2 efflux and stem temperature (0. 24 < R~2 < 0. 78). The temperature coefficient (b) and regression coeffi-cient (R~2) were higher at nighttime than at daytime, and the Q_(10) value ranged from 2. 01 to 2. 79. The stem CO_2 efflux correlated significantly with the xylem CO_2 concentration, and the best regression curve was cubic (R~2= 0. 48). Excluding the effects of stem temperature, the stem CO_2 efflux showed a significant negative correlation with xylem sap flux density (r =-0.462). Therefore, only using simple temperature function to estimate stem CO_2 efflux would yield a significant error, and xylem sap flux should be taken into consideration in the stem CO_2 emux estimation.     

近56年来科尔沁沙地气候变化特征

根据1951-2006年的气温和降水资料,研究了干旱少雨、生态环境脆弱、土地荒漠化严重的科尔沁沙地近56年的气候变化特征.结果表明:1951-2006年,科尔沁沙地的气温以0.28℃·10 a~(-1)的速度上升,远大于全球近50年来0.13℃·10 a~(-1)的平均增温速率;各季节气温都呈上升趋势,冬、春季增温速率极显著(P<0.001),增温速率分别为0.46和0.39℃·10 a~(-1);年最高气温(0.17℃·10 a~(-1))与年最低气温(0.42℃·10 a~(-1))均呈极显著地增加趋势(P<0.01);降水量年际间波动较大,无明显的变化趋势,各季节降水量也没有明显的变化规律;年降水日数呈显著减少趋势(1.3 d·10 a~(-1)),各季的降水日数虽都有逐年减少趋势,但没有达到显著水平;年降水强度和各季降水强度都没有明显的变化规律;年总小雨日数呈显著的减少趋势(P<0.05),减少速率为1.0 d·10 a~(-1).

Abstract：

Based on the 1951-2006 air temperature and precipitation data from seven meteoro-logical stations in Horqin Sandy Land, the past 56-year climate change characteristics in this semi-arid area with vulnerable eco-environment and severe land desertification were analyzed. From 1951 to 2006, the mean annual air temperature in this area increased by 0. 28℃·10 a~(-1), much higher than the global average value of 0.13℃·10 a~(-1) in recent 50 years. The increasing trend of the temperature appeared in all four seasons, but was only significant in winter and spring (P<0.01), with an increasing rate of 0. 46℃·10 a~(-1) and 0.39℃·10 a~(-1), respec-tively. Both the maximum and the minimum mean annual temperatures increased significantly (P <0. 01), and the increasing rate was about 0.17℃·10 a~(-1) and 0.42℃·10 a~(-1), respec-tively. The annual precipitation fluctuated among years, with no obvious change trend at yearly and seasonal scales, while the precipitation days decreased significantly at yearly scale (1.3 d·10 a~(-1)) but not at seasonal scale. No obvious change patterns were observed in the precipitation intensity both in yearly and seasonal scales. The annual light-rain days decreased significant (P <0.05) in a rate of 1.0 d·10 a~(-1).     

纳米粒载体研究进展

目的:介绍纳米粒载体的制备、优点和应用进展,为纳米粒在新的领域的应用提供依据.方法:以纳米粒制备方法和基质材料的不断发展以及各个领域的应用为线索来综述.结果:纳米粒的制备方法有离子交换法、乳化法和自组装法,基质材料有蛋白质和多糖等,纳米粒本身无毒性,能增加所载物的溶解度和生物利用度,提高靶向性及效率,在抗肿瘤治疗、神经系统治疗和药物检测等多方面有广泛的应用.结论:纳米粒作为一种载体,在药物临床研究、药理研究和生物分析等方面都得到了广泛应用,并有可能开发为其他领域的运送体系,有广阔的应用前景.