植物丝氨酸羧肽酶样酰基转移酶的结构、功能和应用

植物丝氨酸羧肽酶样酰基转移酶与丝氨酸羧肽酶相比具有相似的结构特点和很高的同源性,能够催化酰基葡萄糖酯的酰基转移反应,参与植物次生代谢产物的酰基化修饰,丰富天然产物结构多样性,改善化合物水溶性、稳定性等理化性质.本文重点介绍植物来源丝氨酸羧肽酶样酰基转移酶家族的结构特点、催化机制、功能鉴定及其生物催化应用等方面的研究进展...     

日本血吸虫中国大陆株28kDa GST基因在大肠杆菌中的表达

在大肠杆菌ＴＢ１中表达含日本血吸虫中国大陆株２８ｋＤａ抗原基因的重组质粒，表达产物是融合蛋白，分子量来３３ｋＤａ。采用谷胱甘肽琼脂糖亲和层析柱纯化表达产物。２，４－二硝基氯苯／谷胱甘肽分光光度测定法和琼脂糖－淀粉凝胶电泳显示重组抗原具有较高的谷胱甘肽Ｓ－转移酶活力。     

氚—烟酰苯胺在钉螺体内分布示踪的研究

本文应用氚－烟酰苯胺标记湖北钉螺，示踪观察不同时间烟酰苯胺进入螺体组织和脏器内的分布和进入途径。结果显示，钉螺接触药物从２２分钟开始检测出组织、脏器内氚含量，以后逐渐增高，至１４４０分钟达最高峰；合计不同时间各组织和脏器中药物含量由高至低排列次序为外套膜、胃肠、肝脏、肠内粪梗、睾丸、卵巢、鳃、神经节、心脏；转换氚含量为烟酰苯胺剂量，证实了烟酰苯胺杀螺的低用量与高效性；由单位重量组织和脏器中药物含量排位，反映出药物在螺体分布动态变化，以及药物通过消化系统、呼吸系统、外套膜表皮三条途径进入。     

针刺对去卵巢大鼠脑内胆碱乙酰转移酶基因表达的影响

本工作旨在探讨雌激素对脑内乙酰胆碱生成的影响和电针刺激“足三里”穴对去卵巢大鼠脑内乙酰胆碱生成的调整作用。实验选用成年Wistar雌性大鼠,将动物分为正常对照组(INT)、去卵巢组(OVX)和去卵巢针刺组(OVX AC)。用放射免疫分析方法测定血中雌二醇含量,采用RT-PCR方法获得大鼠脑内胆碱乙酰转移酶(ChAT)mRNA的逆转录表达产物——cDNA,用琼脂糖凝胶电泳方法检测,并通过原位杂交方法观察海马ChAT mRNA阳性神经元的表达,然后用计算机图像分析系统进行统计分析。实验结果显示：去卵巢组大鼠体内雌激素水平明显降低,脑内ChAT mRNA的RT-PCR产物和海马ChAT mRNA阳性表达产物的平均面积、平均积分光度值均明显减少,与对照组和针刺组比较有显著性差异;去卵巢针刺“足三里”穴组与去卵巢组相比,大鼠血中雌激素水平明显升高,脑内ChAT mRNA RT-PCR产物明显增多,海马的ChAT mRNA表达阳性神经元增多。以上结果提示：脑内ChAT基因表达与体内雌激素水平有密切关系,去卵巢后针刺“足三里”穴对ChAT的调节作用可能是针刺增强脑内乙酰胆碱含量的机制之一。     

LPC对缺血心肌起搏离子流的影响及ISO的效应

目的:观察在缺血条件下,溶血磷脂酰胆碱(LPC)对心肌起搏离子流(If)的影响以及能否被异丙肾上腺素(ISO)逆转.方法:采用双微电极电压钳制术,在各钳制电位测定并比较缺血心肌加入LPC和LPC加ISO的起搏离子流(If)幅值.结果:缺血降低If幅值,在模拟缺血液中加入LPC 2×10-5mol/L,If幅值在Ec -80～-120 mV水平进一步显著降低(n=5,P<0.05),加重了缺血对If离子流的抑制作用.在模拟缺血液中同时加入LPC 2×10-5mol/L和ISO 1×10-6mol/L,If幅值在Ec -90～-120 mV水平比模拟缺血时有显著增加(n=8,P<0.05),但未能达到缺血前基础水平.结论: 急性心肌缺血时,毒性代谢产物 LPC 加重起搏离子流的受抑程度,即使局部儿茶酚胺大量释放和积聚,也不能完全逆转上述抑制效应.     

DNA chip-based expression profile analysis indicates involvement of the phosphatidylinositol signaling pathway in multiple plant responses to hormone and abiotic treatments

The phosphatidylinositol (PI) metabolic pathway is considered critical in plant responses to many environmental factors, and previous studies have indicated the involvement of multiple PI-related gene families during cellular responses.Through a detailed analysis of the Arabidopsis thaliana genome, 82 polypeptides were identified as being involved in PI signaling. These could be grouped into different families including PI synthases (PIS), PI-phosphate kinases (PIPK),phospholipases (PL), inositol polyphosphate phosphatases (IPPase), inositol polyphosphate kinases (IPK), PI transfer proteins and putative inositol polyphosphate receptors. The presence of more than 10 isoforms of PIPK, PLC, PLD and IPPase suggested that these genes might be differentially expressed during plant cellular responses or growth and development. Accordingly, DNA chip technology was employed to study the expression patterns of various isoforms.In total, 79 mRNA clones were amplified and used for DNA chip generation. Expression profile analysis was performed using samples that represented multiple tissues or cellular responses. Tested samples included normal leaf, stem and flower tissues, and leaves from plants treated with various hormones (auxin, cytokinin, gibberellin, abscisic acid and brassinosteroid) or environmental factors (temperature, calcium, sodium, drought, salicylic acid and jasmonic acid).Results showed that many PI pathway-related genes were differentially expressed under these experimental conditions.In particular, the different isoforms of each family were specifically expressed in many cases, suggesting their involvement in tissue specificity and cellular responses to environmental conditions. This work provides a starting point for functional studies of the relevant PI-related proteins and may help shed light onto the role of PI pathways in development and cellular responses.     

磷脂酰甘油分子种与杨树抗寒性关系的研究

用高效液相色谱（ＨＰＬＣ）方法分析了杨树叶磷脂酰甘油（ＰＧ）的分子种组成,用酶解和气相色谱（ＧＣ）方法分析了ＰＧ脂肪酸定位,比较了抗寒性不同的杨树叶片ＰＧ分子种。结果表明,杨树叶片ＰＧ主要含有以下的分子种脂肪酸组成（ｓｎ－１和ｓｎ－２）：１８：１８：２（１８：２／１８：３）,１８：３／１６：１（３ｔ）;１８：３／１６：０;１８：２／１６：１（３ｔ）;１６：０／１８：２,１８：２／１６：０;１８：１     

PH结构域的结构和功能研究进展

PH结构域是一种存在于多种信号转导蛋白和细胞骨架蛋白中的大约由120个氨基酸组成的功能性区域.不同蛋白质中的PH结构域在一级结构上的同源性并不很高,但其空间结构中肽链主链的折叠方式基本相同,而主要差别存在于其中的三个可变环上,含有这些环的侧面带有正电荷,被认为可能是其配体的结合部位.目前已知的配体有G蛋白βγ亚单位（Gβγ）、蛋白激酶C（PKC）和磷脂酰肌醇衍生物（PIP₂或IP₃）,所以PH 结构域可能介导信号蛋白与这些分子间的相互作用,参与细胞信号转导网络的构成.     

An Arabidopsis embryonic lethal mutant with reduced expression of alanyl—t RNA synthetase gene

In present paper,one of the T-DNA insertional embryonic lethal mutant of Arabidopsis is identified and designated as acd mutant.The embryo developmant of this mutant is arrested in globular stage,The cell division pattern is abnormal during early embryogenesis and results in distubed cellular differentiation.Most of mutant embryos are finally degenerated and aborted in globular stage,However,a few of them still can germinate in agar palte and produce seedlings with shoter hypoctyl and distorted shoot meristem.To understand the molecular basis of the phenotype of this mutant,the joint fragment of T-DNA/plant DNA is isolated by plasmid rescue and Dig-labeled as probe for cDNA library screening.According to the sequence analysis and similarity searching,a 936 bp cDNA sequence(EMBL accession #:Y12555)from selectoed positive clone shows a 99.8%(923/925bp) sequence homolgy with Alanyl-tRNA Synthetase(AlaRS) gene of Arabidopsis thaliana.Furthermore,the data of in situ hybridization experiment indicate that the expression of Ala RS gene is weak in early embryogenesis and declines along with globular embryodevelopment in this mutant Accordingly,the reduced expression of Ala RS gene may be closely related to the morphological changes in early embryogenesis of this lethal mutant.