O'Leary S A, Burnell A M, Kusel J R
Department of Biology, National University of Ireland Maynooth, Co. Kildare, Ireland.
Parasitology. 1998 Oct;117 ( Pt 4):337-45. doi: 10.1017/s0031182098003151.
Entomopathogenic nematodes (EPN) are useful biological control agents of insect pests. However, the infective juvenile (IJ) stage which is the only stage to occur outside the host is susceptible to environmental extremes such as desiccation. We have isolated desiccation-tolerant strains of the EPN Heterorhabditis megidis. In this paper we describe the surface properties of these desiccation-tolerant mutants. Heterorhabditid IJs retain the sheath of the previous larval stage. The mutant lines possess alterations in the surface properties of the sheath. Differences were observed in fluorescent lipid analogue insertion into the surface of the sheath. Furthermore, cationized ferritin-binding studies demonstrated that the mutant lines possessed an increase in net negative surface charge. Removal of the surface layer of the sheath resulted in the loss of the mutant phenotype and in a reduction in the desiccation tolerance of the parental strain. Therefore, the negatively charged 'surface coat' appears to play an important role in the desiccation tolerance of Heterorhabditis species.
昆虫病原线虫（EPN）是有用的害虫生物防治剂。然而，感染性幼虫（IJ）阶段是唯一在宿主体外出现的阶段，它易受干燥等极端环境的影响。我们已经分离出了耐干燥的巨型异小杆线虫（Heterorhabditis megidis）菌株。在本文中，我们描述了这些耐干燥突变体的表面特性。异小杆线虫的感染性幼虫保留了前一幼虫阶段的鞘。突变株系在鞘的表面特性上存在改变。在荧光脂质类似物插入鞘表面的情况中观察到了差异。此外，阳离子化铁蛋白结合研究表明，突变株系的净负表面电荷增加。去除鞘的表面层导致突变表型丧失，并且亲代菌株的耐干燥性降低。因此，带负电荷的“表面涂层”似乎在异小杆线虫属的耐干燥性中起重要作用。
