不同培养基上繁殖的昆虫病原线虫格氏线虫表皮蛋白的差异

Difference of surface coat proteins in entomopathogenic nematode Steinernema glaseri(Rhabditida:Steinernematidae) reared on different culture media

表皮蛋白(surface coat proteins,SCPs)是格氏线虫Steinernema glaseri克服寄主免疫系统的关键因素,能够抑制昆虫免疫反应,促进线虫的侵染。为了进一步研究表皮蛋白抑制昆虫免疫的作用机理和线虫与寄主间的相互关系,我们比较分析了不同培养基繁殖的格氏线虫表皮蛋白的差异。我们用人工培养基和大蜡螟Galleria mellonella末龄(5龄)幼虫分别培养得到格氏线虫侵染期幼虫,利用酒精提取表皮蛋白。SDS-PAGE和非变性PAGE分析显示,大蜡螟来源的格氏线虫的表皮蛋白具有更多的蛋白条带。体外和体内的裂解血细胞实验表明,大蜡螟来源的格氏线虫的表皮蛋白表现出强烈的裂解血细胞活性,而人工培养基来源的格氏线虫的表皮蛋白活力不明显;且具有裂解血细胞活性的表皮蛋白为诱导表达型蛋白。不同培养基来源的格氏线虫的表皮蛋白组成的差异和活性的不同,表明格氏线虫表皮蛋白的产生受线虫培养条件影响较大。

Surface coat proteins （SCPs） of Steinernema glaseri were proved to play important roles in defeating the host immune system. SCPs suppress insect immune response and promote infection of entomopathogenic nematodes. In this study, influences of different culture media on SCPs were investigated, which may provide useful information for further studying the immunosuppressive mechanisms of SCPs and the relationship between entomopathogenic nematodes and their hosts. Infectivejuveniles of S. glaseri were reared on an artificial medium and the last （5th） instar larvae of GaUeria mellonella, respectively, and the SCPs from these nematodes were extracted with ethanol. SDS-PAGE and native-PAGE analysis of SCPs indicated that SCPs from S. glaseri nematodes reared on G. mellonella displayed more protein bands than those from the nematodes reared on the artificial medium. SCPs from S. glaseri nematodes reared on G. mellonella larvae had intensive lytic activity against hemocytes of G. melloneUa both in vitro and in vivo, while SCPs from the nematodes reared on the artificial medium showed weak lytic activity. Moreover, hemocyte lytic SCPs were found to be inducible proteins. Variation of components and activity of SCPs from nematodes reared on different culture media demonstrates that the production of SCPs mainly depends on culture environments.