The LIM domain-containing Dbm1 GTPase-activating protein is required for normal cellular morphogenesis in Saccharomyces cerevisiae.

Normal cell growth in the yeast Saccharomyces cerevisiae involves the selection of genetically determined bud sites where most growth is localized. Previous studies have shown that BEM2, which encodes a GTPase-activating protein (GAP) that is specific for the Rho-type GTPase Rho1p in vitro, is required for proper bud site selection and bud emergence. We show here that DBM1, which encodes another putative Rho-type GAP with two tandemly arranged cysteine-rich LIM domains, also is needed for proper bud site selection, as haploid cells lacking Dbm1p bud predominantly in a bipolar, rather than the normal axial, manner. Furthermore, yeast cells lacking both Bem2p and Dbm1p are inviable. The nonaxial budding defect of dbm1 mutants can be rescued partially by overproduction of Bem3p and is exacerbated by its absence. Since Bem3p has previously been shown to function as a GAP for Cdc42p, and also less efficiently for Rho1p, our results suggest that Dbm1p, like Bem2p and Bem3p, may function in vivo as a GAP for Cdc42p and/or Rho1p. Both LIM domains of Dbm1p are essential for its normal function. Point mutations that alter single conserved cysteine residues within either LIM domain result in mutant forms of Dbm1p that can no longer function in bud site selection but instead are capable of rescuing the inviability of bem2 mutants at 35 degrees C.     

Characterization of universal small-subunit rRNA hybridization probes for quantitative molecular microbial ecology studies.

Universal oligonucleotide hybridization probes targeting the small-subunit rRNA are commonly used to quantify total microbial representation in environmental samples. Universal probes also serve to normalize results obtained with probes targeting specific phylogenetic groups of microorganisms. In this study, six universal probes were evaluated for stability of probe-target duplexes by using rRNA from nine organisms representing the three domains of Bacteria, Archaea, and Eucarya. Domain-specific variations in dissociation temperatures were observed for all probes. This could lead to a significant bias when these probes are used to quantify microbial populations in environmental samples. We suggest lowering the posthybridization wash stringency for two of the universal probes (S-*-Univ-1390-a-A-18 and S-*-Univ-1392-a-A-15) examined. These two probes were evaluated with traditional and modified hybridization conditions to characterize defined mixtures of rRNAs extracted from pure cultures and rRNA samples obtained from anaerobic digester samples. Probe S-*-Univ-1390-a-A-18 provided excellent estimations of domain-level community composition of these samples and is recommended for future use in microbial ecology studies.     

甜菜碱醛脱氢酶在菠菜叶细胞中的定位

将菠菜叶片匀浆后．用差速离心和梯度率心分离叶绿体、过氧物酶体、微粒体等细胞器和１０００００×ｇ上清法部分。用酶活测定法测定各部分甜菜碱醛脱氢酶（ＢＡＤＨ）的活性;用免疫扩散法鉴定各组分的ＢＡＤＨ。除叶绿体外,过氧物酶体、微粒体．以及１０００００×ｇ上清液中也存在ＢＡＤＨ。     

有机硅橡胶固定化细胞进行的生物转化

有机硅橡胶固定化细胞进行的生物转化潘冰峰,戴学倩,冯青,李祖义（中国科学院上海有机化学研究所,２０００３２）关键词硅橡胶;白地霉;固定化细胞;生物转化近年来,有机化学领域的一个重要进展是用酶或微生物进行生物转化反应。其中研究和应用较多的是碳基还原,特...     

Neurotrophin-4/5, brain-derived neurotrophic factor,and neurotrophin-3 promote survival of cultured vestibular ganglion neurons and protect them against neurotoxicity of ototoxins

The ability of neurotrophin-4/5 (NT-4/5), brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), and nerve growth factor (NGF) to promote survival of postnatal rat vestibular ganglion neurons (VGNs) was examined in dissociated cell cultures. Of the four neurotrophins, NT-4/5 and BDNF were equally effective but more potent than NT-3 in promoting the survival of VGNs. In contrast, NGF showed no detectable effects. As expected, TrkB-IgG (a fusion protein of extracellular domain of TrkB and Fc domain of human immunoglobulin G) specifically inhibited the survival-promoting effects by NT-4/5 or BDNF and TrkC-IgG fusion protein completely blocked that of NT-3. Immunohistochemistry with TrkB, TrkA, and p75 antisera revealed that VGNs made TrkB and p75 proteins, but not TrkA protein. Ototoxic therapeutic drugs such as cisplatin and gentamicin often induce degeneration of hair cells and ganglion neurons in both auditory and vestibular systems that leads to impairment of hearing and balance. When cisplatin and gentamicin were added to the dissociated VGN culture in which the hair cells were absent, additional cell death of VGNs was induced, suggesting that the two ototoxins may have a direct neurotoxic effect on ganglion neurons in addition to their known toxicity on hair cells. However, if the cultures were co-treated with neurotrophins, NT-4/5, BDNF, and NT-3, but not NGF, prevented or reduced the neurotoxicity of the two ototoxins. Thus, the three neurotrophins are survival factors for VGNs and are implicated in the therapeutic prevention of VGN loss caused by injury and ototoxins. © 1995 John Wiley & Sons, Inc.     

大兴安岭林区针叶林的生长方程及火灾林木死亡率

本文用随机模拟的方法建立了北方针叶林的生长方程及其受到火灾侵害后的林木死亡率,定量地研究了火灾对这种林分变动的影响．     

寡糖素对红花及三七培养细胞的生理作用

三种寡糖素,即来自人参（Ｐａｎａｘ ｇｉｎｓｅｎｇ）培养细胞的人参寡糖素、红花（Ｃａｒｔｈａｍｕｓ ｔｉｎｃｔｏｒｉｕｓ）培养细胞的红花寡糖素、黑节草（Ｄｅｎｄｒｏｂｉｕｍ ｃａｎｄｉｄｕｍ）植物的黑节草寡糖素对红花及三七（Ｐａｎａｘ ｎｏｔｏｇｉｎｓｅｎｇ）的培养细胞的生长及代谢产物的含量均有显著的促进作用。寡糖素可耐高温高压（１２１℃、．ｂｓ／ｃｍ＾２）灭菌１５分钟而不失活,其对植物培养细胞的     

酪氨酸羟化酶基因载体－pCMVTH 质粒的构建及在大鼠骨骼肌内的表达

为用转基因方法治疗巴金森氏病大鼠模型,本研究采用分子克隆技术,将合成多巴胺的关键酶－酪氨酸羟化酶（ＴＨ）的基因,克隆进入以巨细胞病毒ＣＭＶ为启动子的载体质粒内,经限制性内切酶定位分析证实该重组的ＤＮＡ质粒的可靠性。携带ＴＨ基因的ＰＣＭＶＴＨ质粒以ＬＩＰＯ－ＦＥＣＴＩＮ介导,在培养的原代骨骼肌细胞中高效表达。本研究为进一步用转基因的细胞植入脑内以治疗巴金森氏病打下一定基础。     

少年人群接种乙肝疫苗后七年随访观察

对７９名ＨＢＶ标志阴性少年人群,以乙肝疫苗１０μｇ×３的免疫剂量和０、１、２月的免疫程序进行接种,对其抗－ＨＢｓ免疫应答和临床保护效果作了为期７年的定人随访。结果表明,抗－ＨＢｓ阳转率在免后三个月时为１００％,均值为３０８４ＭＩＵ／ｍｌ。至免后８４个月时疫苗接受者中仍有５５．７％的抗－ＨＢｓ水平≥１０ＭＩＵ／ｍｌ。６例检出抗－ＨＢｓ,其中５例的抗－ＨＢｓ持续处于高水平。全部观察对象无一例检出ＨＢｓＡｇ或发生临床肝炎。少年接种乙肝血源疫苗至少７年内可具有保护性抗体。故在此期内不需加强免疫。     

野生紫斑牡丹和四川牡丹种子萌发特性及与其致濒的关系

野生牡丹种子一般较小,而且不同产地之间形状、大小差异较大。其萌发特性与栽培牡丹相比也有较大差异：萌发期长达半年以上,且萌发温度在１０～１５℃为宜,超过２０℃则明显不利于生根及上胚轴生长。四个不同分布地的四川牡丹种子萌发率较一致,均在６０～７７％之间。三个不同产地的紫斑牡丹种子萌发率则相差甚远,分布于甘肃文县的萌发率达７６％,而分布于陕西略阳和湖北神农架的萌发率则分别只有１２％和４．４％,出苗率则更低。本文认为紫斑牡丹的种子特性是其在自然界处于濒危状态的重要原因之一。