水稻蜡质基因5＇上游区缺失对基因表达的影响

为研究水稻蜡质基因（ｗａｘｙ）５＇上游调控区中存在的顺式作用元件,我们将水稻ｗａｘｙ基因翻译起始声、（ＡＴＧ）５＇上游３．４ｋｂ（－２１１８～＋１２９１ｂＰ）片段经外切核酸酶ＥｘｏⅢ部分酶解,得到一系列５＇端缺失的片段。将这些缺失片段分别与ｇｕｓ基因编码区连接,构建成融合质粒,经ＰＥＧ介导引入水稻原生质体,２６℃培养４８ｈ后,定量测定ＧＵＳ酶活力,并以同时导入的由３５Ｓ启动子指导的荧光素酶（ＬＵＣ）基因表达的酶活力作为内对照。结果表明,ＧＵＳ酶活性随５’上游调控区长度的减少而逐渐减弱。由─８６１ｂｐ缺失至─６４０ｂＰ时,ｇｕｓ基因表达水平有较明显的降低,推测在该区域中可能存在一个顺式作用元件区。     

The size distribution of insertions and deletions in human and rodent pseudogenes suggests the logarithmic gap penalty for sequence alignment

The size distributions of deletions, insertions, and indels (i.e., insertions or deletions) were studied, using 78 human processed pseudogenes and other published data sets. The following results were obtained: (1) Deletions occur more frequently than do insertions in sequence evolution; none of the pseudogenes studied shows significantly more insertions than deletions. (2) Empirically, the size distributions of deletions, insertions, and indels can be described well by a power law, i.e., f _k = Ck ^–b , where f _k is the frequency of deletion, insertion, or indel with gap length k, b is the power parameter, and C is the normalization factor. (3) The estimates of b for deletions and insertions from the same data set are approximately equal to each other, indicating that the size distributions for deletions and insertions are approximately identical. (4) The variation in the estimates of b among various data sets is small, indicating that the effect of local structure exists but only plays a secondary role in the size distribution of deletions and insertions. (5) The linear gap penalty, which is most commonly used in sequence alignment, is not supported by our analysis; rather, the power law for the size distribution of indels suggests that an appropriate gap penalty is w _k = a + b ln k, where a is the gap creation cost and blnk is the gap extension cost. (6) The higher frequency of deletion over insertion suggests that the gap creation cost of insertion (a _i ) should be larger than that of deletion (a _d ); that is, a _i – a _d = In R, where R is the frequency ratio of deletions to insertions. Correspondence to: W.-H. Li     

Purification and characterization of 2,6-dichloro-p-hydroquinone chlorohydrolase from Flavobacterium sp. strain ATCC 39723.

The biochemistry of pentachlorophenol (PCP) degradation by Flavobacterium sp. strain ATCC 39723 has been studied, and two enzymes responsible for the conversion of PCP to 2,6-dichloro-p-hydroquinone (2,6-DiCH) have previously been purified and characterized. In this study, enzymatic activities consuming 2,6-DiCH were identified from the cell extracts of strain ATCC 39723. The enzyme was purified to apparent homogeneity by a purification scheme consisting of seven steps. Gel filtration chromatography showed a native molecular weight of about 40,000, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed a single protein of 42,500 Da. The purified enzyme converted 2,6-DiCH to 6-chlorohydroxyquinol (6-chloro-1,2,4-trihydroxybenzene), which was easily oxidized by molecular oxygen and hard to detect. The end product, 6-chlorohydroxyquinol, was detected only in the presence of a reductase and NADH in the reaction mixture. The enzyme dechlorinated 2,6-DiCH but not 2,5-DiCH. The enzyme required Fe2+ for activity and was severely inhibited by metal chelating agents. The optimal conditions for activity were pH 7.0 and 40 degrees C. The Kcat for 2,6-DiCH was 35 microM, and the kcat was 0.011 s-1.     

两种吸血水蛭对光闪烁和水扰动刺激的反应

利用自制的控温实验槽在暗室内进行医蛭科两种吸血水蛭对光闪烁和水扰动刺激的模拟个体生态实验,实验结果的统计分析表明,日本医蛭在１６℃时与照度有极好的正相关关系,而在２２℃时成负相关关系,０．２克体重的个体在两种温度对照度的敏感度均大于０．５－０．６克和１．０－１．３克体重的个体,湖北牛蛭在两种温度时与照度均成正相关关系;０．５克体重的个体在１６℃时对照度的敏感度大于１．０－３．３克体重的个体９．５－     

鼠脑突触体Mg^2＋—ATP酶质子泵活性的研究

位于突触体质膜的外向型（ｅｃｔｏ）Ｍｇ＾２－ＡＴＰ酶具有水解ＡＴＰ活性,能量偶联的ＡＣ－ＭＡ荧光淬灭实验表明Ｍｇ＾２＋－ＡＴＰ酶水解ＡＴＰ时向膜内转移质子,建立跨膜质子梯度,跨膜质子梯度可以被电中性Ｋ＾＋／Ｈ＾＋离子载体Ｎｉｇｅｒｉｃｉｎ消除,利用Ｈ＾＋敏感的ＢＣＥＣＦ荧光分子测定突触的ｐＨｉ变化,结果表明水解ＡＴＰ产生的质子转移突触体ｐＨｉ下降了光分子测定突触的ｐＨｉ变化,结果表示水解ＡＴＰ产生     

Purification and Properties of Component B of 2,4,5-Trichlorophenoxyacetate Oxygenase from Pseudomonas cepacia AC1100

Pseudomonas cepacia AC1100 degrades 2,4,5-trichlorophenoxyacetate (2,4,5-T), an herbicide and chlorinated aromatic compound. Although some progress has been made in understanding 2,4,5-T degradation by AC1100 by molecular analysis, little is known about the biochemistry involved. Enzymatic activity converting 2,4,5-T to 2,4,5-trichlorophenol in the presence of NADH and O(inf2) was detected in cell extracts of AC1100. Phenyl agarose chromatography of the ammonium sulfate-fractionated cell extracts yielded no active single fractions, but the mixing of two fractions, named component A and component B, resulted in the recovery of enzyme activity. Component B was further purified to homogeneity by hydroxyapatite and DEAE chromatographies. Component B had a native molecular weight of 140,000, and it was composed of two 49-kDa (alpha)-subunits and two 24-kDa (beta)-subunits. Component B was red, and its spectrum in the visible region had maxima at 430 and 560 nm (shoulder), whereas upon reduction it had maxima at 420 (shoulder) and 530 nm. Each mole of (alpha)(beta) heterodimer contained 2.9 mol of iron and 2.1 mol of labile sulfide. These properties suggest strong similarities between component B and the terminal oxygenase components of the aromatic ring-hydroxylating dioxygenases. Component A was highly purified but not to homogeneity. The reconstituted 2,4,5-T oxygenase, consisting of components A and B, converted 2,4,5-T quantitatively into 2,4,5-trichlorophenol and glyoxylate with the coconsumption of NADH and O(inf2).     

神经生长因子家族及其受体研究进展

过去几年在神经营养因子、受体和神经元细胞程序性死亡的研究领域中取得了几项引人注目的进展：（１）神经生长因子（ＮＧＦ）基因家族的其他一些成员包括脑源性神经营养因子（ＢＤＮＦ）、神经营养素－３（ＮＴ－３）、神经营养素－４（ＮＴ－４）、神经营养素－５（ＮＴ－５）的发现;（２）神经生长因子三维结构及功能和进化之关系的阐明;（３）定性了两种神经生长因子受体Ｐ７５＾ＮＧＦＲ和原癌基因ｐ１４０＾ｔｒｋＡ以及相关     

大鼠中脑腹侧被盖区在睡眠－觉醒调节中的作用

本实验在３１只清醒自由行动的雄性ＳＤ大鼠进行。结果如下：（１）双侧中脑腹侧被盖区（ＶＴＡ）微量注射３．３ｎｍｏｌ溴隐亭后第２—３ｈ觉醒时间显著增加（Ｐ＜０．０１）;６．６ｎｍｏｌ溴隐亭有类似效果;０．６６和１．３３ｎｍｏｌ溴隐亭无明显作用。（２）同样方法ＶＴＡ微量注射２ｎｍｏｌ和４ｎｍｏｌＳＣＨ２３３９０后第２—３ｈ觉醒时间明显减少（分别为Ｐ＜０．０１和Ｐ＜０．０５）,但注射３．４ｎｍｏｌ舒必利则无效。（３）红藻氨酸（０．３μｇ）双侧ＶＴＡ注后一周,大鼠白天觉醒减少,夜间无明显变化。以上结果表明溴隐亭微量注射到ＶＴＡ可能通过Ｄ１受体使多巴胺神经元活动增加而产生致觉醒作用;另外ＶＴＡ中ＤＡ神经元对于维持日间的觉醒可能有紧张性作用。     

人胚DA能神经元移植于帕金森氏病猴模型的TH免疫细胞化学的研究

为了对人胚黑质ＤＡ神经元移植治疗ＰＤ人的临床应用作出客观评估,将８－１２周人胚黑质细胞移植到用ＭＰＴＰ诱发的偏侧ＰＤ猴新纹状体内。实验动物分别存活２个月、５个月和１年后,用ＴＨ免疫细胞化学方法对被移植的人胚ＤＡ细胞的存活和与宿主间的突触联系进行检查。在光镜下可见被移植侧的新纹状体内有ＴＨ阳性细胞,它们成小群散在分布,每小群有３－１０个细胞。ＴＨ阳性细胞的轴突延伸到整个新纹状体,树突呈现出正常发育过     

中国洞穴盲虾一新种(十足目:匙指虾科)

本文记述采自广西桂林洞穴中的盲米虾属一新种,半盲米虾Ｔｙｐｈｌｏｃａｒｉｄｉｎａｓｅｍｉｔｙｐｈｌａｔａｓｐ．ｎｏｖ．,新种眼角膜色素未完全退化,额剑上下缘均具齿。