A small GTP-binding protein dissociates from synaptic vesicles during exocytosis.

Low-molecular-weight GTP-binding proteins are strong candidates for regulators of membrane traffic. In yeast, mutations in the sec4 or ypt1 genes encoding small GTP-binding proteins inhibit constitutive membrane flow at the plasma membrane or Golgi complex, respectively. It has been suggested that membrane fusion-fission events are regulated by cycling of small GTP-binding proteins between a membrane-bound and free state, but although most of these small proteins are found in both soluble and tightly membrane-bound forms, there is no direct evidence to support such cycling. In rat brain a small GTP-binding protein, rab3A, is exclusively associated with synaptic vesicles, the secretory organelles of nerve terminals. Here we use isolated nerve terminals to study the fate of rab3A during synaptic vesicle exocytosis. We find that rab3A dissociates quantitatively from the vesicle membrane after Ca2(+)-dependent exocytosis and that this dissociation is partially reversible during recovery after stimulation. These results are direct evidence for an association-dissociation cycle of a small GTP-binding protein during traffic of its host membrane.     

牛奶的微生物学检验

为提高牛奶的食用价值，以选择最佳的灭菌方法，最佳的贮存温度及有效存放时间，对临汾地区奶牛场的牛奶进行了生物学检验，从而得出了牛奶的最佳灭菌方法为巴斯消毒法；牛奶的最佳贮存温度为O℃；有限的存放时间为O℃贮存大约7d，室温(22℃)贮存12h。32℃贮存6h。     

网络技术与伦理道德矛盾的化解

信息网络的发展，促进了社会生产、生活的深刻变革，同时也产生了一系列的网络技术与伦理道德之间的矛盾。网络道德具有自主性、开放性和多元性的特点，化解网络技术与伦理道德矛盾的对策主要包括加强网络主体的道德自律、加强社会主义网络体制改革、加强多元网络道德原则的支持三个方面。     

基于IP多播的机房信息管理系统的设计与实现

提出了一种基于IP多播技术的解决方案并加以实现,满足了对上机学生按系或班级分组进行管理与各类统计的需要,实现了传统C/S结构所能实现的全部功能,解决了传统机房信息管理系统使用带来的问题。     

Specific binding of antigenic peptides to cell-associated MHC class I molecules

T lymphocytes recognize antigen in the form of peptides that associate with specific alleles of class I or class II major histocompatibility (MHC) molecules. By contrast with the clear MHC allele-specific binding of peptides to purified class II molecules purified solubilized class I molecules either bind relatively poorly or show degenerate specificity. Using photo-affinity labelling, we demonstrate here the specific interaction of peptides with cell-associated MHC class I molecules and show that this involves metabolically active processes.     

Characterization of the rough endoplasmic reticulum ribosome-binding activity.

The rough endoplasmic reticulum membranes of mammalian cells contain specific ribosome-binding sites. A purification to apparent homogeneity of a negatively charged protein (ERp180) of relative molecular mass 180,000 (180 K) was reported which was proposed to function as a rough endoplasmic reticulum ribosome receptor. We report here that ribosome-binding site activity quantitatively solubilized from rough endoplasmic reticulum membranes does not cofractionate with ERp180. By contrast, ribosome-binding site activity fractionates as a much smaller, positively charged protein.     

Genotoxic effects of dithane M-45 on the bone marrow cells of mice in vivo

Genotoxic effects of dithane M-45 were studied on the bone marrow cells of male albino mice (Lacca strain) in vivo. Different doses (30 mg, 40 mg and 300 mg/kg b.wt) of dithane M-45 were injected intraperitoneally and their effects were investigated after time intervals of 1, 2, 5 and 10 days. The chromosomal aberrations observed in the bone marrow cells of male mice after treatment with dithane M-45 were fragments, rings, dicentric chromosomes, terminal chromatid deletions, chromatid gaps and breaks. In addition to these chromosomal aberrations, physiological effects such as uneven stretching of chromatin material, end-to-end chromosomal associations, exchange configurations, clumping, stickiness and centromeric associations were also observed.     

秋水仙素诱导青虾次级卵母细胞二倍体初探

以青虾卵巢为材料，采用秋水仙素诱导多倍体次级卵母细胞．经滴片试验，确立此实验最佳滴片高度为1．5cm，通过设置5个秋水仙素浓度(0．08～0．40mg／mL)及3个作用时间(6～24h)，观察发生染色体加倍的细胞相对数目．实验结果表明：在使用秋水仙素的浓度为0．08～0．40mg／mL，处理6～24h时都可以获得多倍体卵细胞．在秋水仙素浓度是0．32mg／mL，处理6h可得到最高二倍体突变率(32．58％)．还测试了0．32mg／mL COM作用6h时ATPase活性与生理盐水对照组的变化，结果显示COM会在一定程度上影响细胞的新陈代谢．但是50％左右的成活率表明，这种诱导突变的方法仍具有一定的应用价值．     

一种利用绝对最小Lipshitz延拓的医学图像插值算法

提出一种基于最小Lipshitz延拓的图像插值半隐式算法,并用医学图像放大实验初步验证了算法的有效性.     

雪灵芝水溶性多糖提取工艺优化及其数学模型的建立

目的 优化雪灵芝水溶性多糖的提取工艺,并建立数学模型.方法 采用水提醇沉法提取雪灵芝水溶性多糖;运用苯酚-硫酸法测定多糖含量;通过单因素实验研究浸提时间、加水比、浸提温度及乙醇浓度对多糖提取率的影响;采用响应面分析法优化提取条件,运用sas软件分析实验数据,建立回归模型.结果 得到雪灵芝水溶性多糖提取的优化工艺参数的最佳取值范围为:浸提温度(94.5～97.5℃);浸提时间(2～2.5h);加水比(43～51v/w).结论 为雪灵芝水溶性多糖提取工艺的优化提供了一定的技术依据,也为其后续研究奠定了基础.