柔嫩艾美耳球虫LZ株MIC-5基因的克隆与表达

提取柔嫩艾美耳球虫兰州株孢子化卵囊总RNA,运用RT-PCR技术扩增Et MIC-5基因片段进行测序,并克隆入大肠杆菌表达载体pET28a中进行诱导表达.结果表明,该基因片段长918 bp,编码306个氨基酸.与GenBank报道的柔嫩艾美耳球虫Houghton株MIC-5基因相比,核苷酸和推导的氨基酸序列同源性为99.2%和99.6%.在推导的MIC-5氨基酸序列中,第15~89、90~160、173~242和245~306位保守的cys残基形成4个Apple样结构域(A-domain),推测该蛋白可能在虫体与宿主细胞的黏附中起重要作用.转化重组质粒pETMIC-5的BL21(DE3)经IPTG诱导后,SDS-PAGE和western blot分析证实目的蛋白成功表达,重组蛋白的表达量可占菌体蛋白的15.2%.     

重叠延伸PCR法扩增猪囊尾蚴AgB基因及其在BHK-21细胞中的表达

 【目的】克隆猪囊尾蚴AgB基因并在体外细胞中表达。【方法】采用 RT-PCR法分别扩增AgB基因的上半段和下半段序列。采用重叠延伸PCR法（splicing overlap extension PCR method,SOE-PCR）把具有35个相同碱基的上下半段扩增为全长基因,并构建到真核表达载体pVAX1,将酶切、PCR、测序鉴定的阳性质粒经脂质体转染 BHK-21细胞。通过SDS-PAGE、Western-blotting、间接免疫荧光法,检测细胞中B抗原的表达。【结果】琼脂糖凝胶电泳显示扩增的不同片段大小分别与预期的相同。重组表达载体转染BHK细胞后有荧光出现。表达的蛋白能被猪囊尾蚴病阳性血清所识别。【结论】通过重叠延伸PCR法成功扩增了AgB基因全长并构建到真核表达载体,目的蛋白在BHK-21细胞中表达。     

Yield penalty of maize (Zea mays L.) under heat stress in different growth stages: A review

Maize (Zea mays L.) can exhibit yield penalties as a result of unfavorable changes to growing conditions. The main threat to current and future global maize production is heat stress. Maize may suffer from heat stress in all of the growth stages, either continuously or separately. In order to manage the impact of climate driven heat stress on the different growth stages of maize, there is an urgent need to understand the similarities and differences in how heat stress affects maize growth and yield in the different growth stages. For the purposes of this review, the maize growth cycle was divided into seven growth stages, namely the germination and seedling stage, early ear expansion stage, late vegetative growth stage before flowering, flowering stage, lag phase, effective grain-filling stage, and late grain-filling stage. The main focus of this review is on the yield penalty and the potential physiological changes caused by heat stress in these seven different stages. The commonalities and differences in heat stress related impacts on various physiological processes in the different growth stages are also compared and discussed. Finally, a framework is proposed to describe the main influences on yield components in different stages, which can serve as a useful guide for identifying management interventions to mitigate heat stress related declines in maize yield.