烟草DREB转录因子新基因的克隆与功能分析

采用同源克隆及cDNA末端快速扩增法(rapid amplification of cDNA ends,RACE),从烟草中克隆到1个新的烟草DREB基因,命名为NbDREB2a.序列分析表明该基因全长1191 bp,编码330个氨基酸,具有典型的DREB转录因子保守的AP2结构域.实时RT-PCR分析表明,该基因能在烟草的根、茎、叶中表达,受低温、干旱和高盐诱导.酵母转录激活实验证明,该基因可以特异性结合DRE顺式作用元件,并能激活报告基因的表达.为了研究该基因在植物抗逆反应中的功能,利用农杆菌介导法,将该基因转化到模式生物拟南芥中,筛选到了单拷贝插入的、纯合的拟南芥株系;对获得的转基因拟南芥进行干旱及高盐处理,结果表明,与对照相比,超量表达该基因能够明显地提高拟南芥对干旱及高盐的抗性.     

一个新的葡萄抗逆转录因子VvERF2基因的In silico克隆及生物信息学分析

ERF是植物所特有的一类重要的转录因子,广泛参与植物生长、发育以及多种生理生化反应的信号传导。本研究利用In silico克隆方法获得葡萄VvERF2基因,并利用生物信息学方法对该基因编码产物从氨基酸组成、理化性质、进化关系、二级及三级结构、功能等方面进行预测和分析。结果表明,VvERF2为亲水性蛋白,与其他物种的ERF在序列组成、结构及活性位点等方面均具有高度的一致性。     

陆地棉“洞A”转录因子GhbZIP1的克隆及表达分析

结合RACE技术与hi-TAIL PCR技术克隆得到1个新的棉花bZIP转录因子的cDNA序列,暂命名为GhbZIP1。该基因包含1个完整的包含471bp的开放阅读框,编码156个氨基酸。GhbZIP1蛋白具有典型的bZIP保守结构域,与拟南芥等植物bZIP1蛋白的保守区相似性较高,推测棉花GhbZIP1与拟南芥AtbZIP1功能类似。此外,qPCR分析表明GhbZIP1基因在洞A可育株花药的4个主要时期(小孢子单核早期、小孢子单核期、双核期及花粉形成期)的表达均明显高于不育株。由此提示,GhbZIP1基因可能与棉花雄性不育相关。     

The oncogenic activation of human p21ras by a novel mechanism

Single amino acid changes were introduced into normal (non-oncogenic) and activated forms of the human H-ras protein at a position (residue 116) proposed on structural grounds to represent a contact site with guanine nucleotides. Substitutions at this site could significantly reduce the ability of both forms to bind and hydrolyze guanosine 5'-triphosphate; these substitutions, however, did not necessarily diminish the transforming capacity of activated derivatives. One substitution that severely impairs these functions activated the transforming potential of the otherwise normal polypeptide.     

Lectin activation in Giardia lamblia by host protease: a novel host-parasite interaction

A lectin in Giardia lamblia was activated by secretions from the human duodenum, the environment where the parasite lives. Incubation of the secretions with trypsin inhibitors prevented the appearance of lectin activity, implicating proteases as the activating agent. Accordingly, lectin activation was also produced by crystalline trypsin and Pronase; other proteases tested were ineffective. When activated, the lectin agglutinated intestinal cells to which the parasite adheres in vivo. The lectin was most specific to mannose-6-phosphate and apparently was bound to the plasma membrane. Activation of a parasite lectin by a host protease represents a novel mechanism of host-parasite interaction and may contribute to the affinity of Giardia lamblia to the infection site.