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短暂和稳定转染载体是研究胞内寄生虫刚地弓形虫速殖子的重要分子工具之一。由于DHFR内包含2个氨基酸突变的DHFRm2m3-TS,具有高水平的乙胺嘧啶抗性,因此已作为多种转染载体的阳性选择标记。DHFR-TS的活性功能区在不同虫种之间具有高度保守性,但是,不同虫种的DHFR和TS的衔接区域之间的同源性很低,推测此衔接区主要起连接DHFR和TS的作用。据此,作者通过将编码FLAG多肽的DNA片段定向克隆到DHFR和TS的衔接区域,构建了一个新的转染载体DHFRm2m3-FLG-TS。
Transient and stable transfection vectors are one of the most important molecular tools for studying the tachyzoites of T. gondii in intracellular parasites. Since DHFR contains 2 amino acid mutations in DHFRm2m3-TS, with high levels of pyrimethamine resistance, it has been used as a positive selection marker for a variety of transfection vectors. The DHFR-TS active functional regions are highly conserved among different species of insects. However, the homology between DHFR and TS of different species is very low. It is presumed that this DHFR-TS is mainly responsible for the interaction between DHFR and TS effect. Accordingly, the authors constructed a new transfection vector DHFRm2m3-FLG-TS by directional cloning of the DNA fragment encoding FLAG polypeptide into the adapter region of DHFR and TS.