UV胁迫酵母细胞凋亡过程的拉曼光谱研究

【目的】了解UV诱导酵母细胞发生凋亡过程中生物大分子的变化及细胞凋亡的分子机制。【方法】应用单细胞激光光镊拉曼光谱技术(LTRS),实时研究酵母细胞凋亡过程中拉曼光谱强度的动态变化,分析单个细胞凋亡过程的生理生化变化。【结果】致死剂量UV照射酵母细胞后,细胞发生凋亡。对于群体细胞,归属于核酸的1085cm-1,1300cm-1,蛋白质的850cm-1,1440cm-1,1604cm-1,1650cm-1和脂类的1085cm-1,1300cm-1,1440cm-1拉曼峰强度都随凋亡时间的延长而降低,反映酵母细胞在凋亡过程中,细胞内核酸、蛋白质、脂质等大分子物质的含量随时间变化逐步减少;1604cm-1下降幅度最大,到凋亡后期下降60%,反映细胞凋亡过程中能量代谢受阻,呼吸产能活力下降,推测与麦角固醇结构与功能改变有关。单个细胞凋亡过程动态的光谱变化显示,归属于蛋白质等生物大分子的光谱强度也呈下降趋势,但是在90~120min和125~167min时间段里,850cm-1,1085cm-1,1300cm-1,1440cm-1和1665cm-1拉曼峰强度出现恢复性的上升和下降过程,说明群体细胞平均后的光谱数据信息,掩盖了个体细胞凋亡过程中一些信息的变化,群体细胞的结果不能完全反映个体细胞真实的生理状态。【结论】LTRS基于单个细胞水平上的研究,能更直接、真实地反映UV胁迫下细胞内生物大分子变化的动态信息。     

一种改良的蛋白质复合物识别方法

高通量的方法产生了大量蛋白质相互作用数据.然而研究表明,对于已过滤的双杂交酵母数据集,假阳性相互作用的比例达到50%左右.这些假阳性这对于进一步的PPI网络研究带来了负面影响.因此,消除假阳性或者降低假阳性带来的负面影响变得非常重要.根据蛋白质相互作用网络的拓扑特性,每一组相互作用被赋予一个存在概率,概率值表示相互作用的可靠程度,概率值为0的相互作用被标识为假阳性予以消除.提出了一种改良的蛋白质复合物识别方法,该方法基于核-附件的思想,识别的复合物具有更强的生物统计特性.改良的新方法及其他经典的识别方法在酵母数据集上得到运行,实验结果表明,改良的方法性能优于现有的经典方法.     

Retinoid X receptor activities of source waters in China and their removal efficiencies during drinking water treatment processes

There is increasing evidence of estrogenic activities of source waters and drinking waters in China based on estrogen receptors(ERs) testing.However,relating such activities to retinoid X receptors(RXRs) in both drinking and source waters are lacking.To rectify this situation,we assessed 23 source water samples from six major river systems in China.We also collected samples at various stages of water processing from three drinking water treatment plants(DWTPs) using a two-hybrid RXR yeast assay with and without metabolism.No RXR agonistic activity was observed,but significant antagonistic activity was detected in all sample extracts.The RXR antagonistic activities of source water sample extracts ranged from 15.2% to 57.8% without metabolism and 11.5% to 68.3% with metabolism,respectively.In the drinking water treatment processes,RXR antagonistic activities without metabolism and with metabolism of up to 31.4% and 37.5% were removed,respectively.Nevertheless,the remaining RXR antagonists in treated drinking water from these source waters could still be harmful to human health.To the best of our knowledge,the occurrence of in vitro RXR disruption activities in source and drinking water has not been previously reported in China.Therefore,an attempt was made to conduct detailed studies investigating RXR disrupting activities and their possible risks in source and drinking water.     

混合菌种发酵生产酱油的工艺研究

利用米曲霉(Aspergillus oryzae)和黑曲霉(Aspergillus niger)混合接种,并在制曲后期混合添加嗜盐片球菌(Pediococus halophilus)和高渗酵母进行多菌种发酵生产酱油实验研究。结果表明,混合发酵的菌种最佳培养时间为36～40h,最佳发酵温度为45～48℃。米曲霉和黑曲霉的接种比为90%∶10%时,全氮利用率提高13.2%,氨基酸生成率提高6.8%。将成熟曲拌以10%的食盐水,在pH值为6.5的环境下,混合添加嗜盐片球菌和高渗酵母参与发酵可以提高酱油产品中的醇类含量和酸类含量,改进酱油的风味。     

Regulatory mechanisms involved in modulating RGS function

Regulator of G-Protein Signaling (RGS) refers to a conserved 120–125 amino acid motif that was first identified by its ability to negatively regulate G-Protein-Coupled Receptor (GPCR) signalling. Mechanistically, RGSs were found to regulate GPCR responses by binding to and stimulating the GTPase activity of the receptor-activated GTP-bound G α subunits. There are now over 25 mammalian RGSs containing proteins that are reported to carry out a variety of functions, many of which are unrelated to GPCR signalling. RGS proteins range in size from small proteins that contain little more than an RGS box to very large proteins that contain a variety of domains. The selectivity of function of the RGS proteins is attributable to the divergence of the RGS sequences as well as the presence of a variety of functional motifs, which allow them to interact with other proteins. Here we focus on the RGSs that are involved in modulating GPCR signalling by reviewing the diversity of the mechanisms involved in regulating these RGSs. Received 9 February 2006; received after revision 4 May 2006; accepted 22 May 2006     

酵母菌耐热性的最适热激条件研究

以安琪抗高温酵母菌YY为研究材料,采用30-48℃的不同温度和10～180min不同的时间对酵母菌进行热激诱导产生耐热性的研究,研究表明最适热激温度为42℃,最适热激时间为30min,产生耐热性后,在50℃处理的时间越长,活力越小,在酵母菌的不同生长时期,菌体达到一定的浓度后,耐热性的产生没有显著影响,从28℃升到热激温度42℃所需时间在30-240min内,时间越长产生的耐热性越强。     

饲料酵母工业的概况和展望

<正>本文对饲料酵母工业的现状,饲料酵母的饲养价值以及发展饲料酵母生产的重要性作了较全面的介绍。饲料酵母的饲养价值相当于鱼粉,大力发展饲料酵母工业是解决我国蛋白质饲料不足的有效途径。该文还就充分利用农、林业纤维废料、有机废液生产饲料酵母等问题提出了有关建议。     

木糖发酵菌株的筛选

本实验利用传统的方法从森林土样中分离筛选出一株能有效发酵木糖生产乙醇的酵母菌株。首先通过富集培养、初筛、复筛等步骤筛选出一株（1#菌株）能够利用木糖的酵母菌株,对其进行了生理生化性能指标试验,初步鉴定为假丝酵母菌（Candida sp.）。并对其进行了利用木糖发酵乙醇试验,实验结果表明：在培养温度为30℃,pH5.0,接种量为10％左右,初始木糖浓度为40g/L时,该菌株可以利用木糖发酵生产乙醇,产乙醇量为1.06g/100mL,相当于理论转化率的56.9%。     

50Hz极低频电磁场对酵母细胞生长和氧化应激的影响初探

探讨50 Hz极低频电磁场(extremely low frequency electromagnetic fields,ELF-EMF)暴露对酵母细胞的生长、细胞内活性氧(ROS)水平,以及超氧化物歧化酶(SOD)和过氧化氢酶(CAT)两种抗氧化酶活性的影响。测定酵母细胞在50 Hz 6 m T ELF-EMF暴露下的菌落形成数目和生长曲线,及ELF-EMF短期暴露(0.5、1、2 h)和长期暴露(6、12、24、96 h)对细胞内ROS水平,以及SOD和CAT活性的影响。实验结果表明,磁感应强度高达6 m T的ELF-EMF暴露下,酵母细胞的菌落形成数目和生长曲线没有发生显著变化(p0.05)。在暴露2 h内,ELF-EMF可显著提高细胞内ROS水平(p0.01);并显著影响酵母细胞内SOD或CAT活性(p0.05)。但暴露时间超过6 h后,酵母细胞内ROS水平、及SOD和CAT活性与对照组大致相同,没有发生显著变化。实验条件下ELF-EMF暴露对酵母的生长没有显著影响,在短期暴露(2 h内)中,可引起酵母细胞内氧化应激反应;但在长期暴露(6 h后)后,对氧化应激反应没有显著影响。