探索生命极限的模式生物——南极土壤自由生活线虫Plectus murrayi及其环境适应性特征

Model Organism Exploring Life Limit——Plectus murrayi,A Free-living Nematode in Antarctic Soil,and Its Environmental Adaptability

针对土壤自由生活线虫的环境适应性及其生态功能研究一直是土壤动物学和生态学的核心内容之一。前期研究表明南极土壤自由生活线虫能够在极端干旱的土壤中生存,尤其是线虫的优势种群之一——Plectus murrayi,在生理生态水平上均表现出独特的适应性。土壤自由生活线虫Plectus murrayi是仅在南极麦克默多山谷(McMurdo Dry Valleys,MDV)发现的主要陆生生物之一,目前已在多领域成为研究极端环境下生态学以及生物学的模式生物。本文旨在综述其系统发育、分布、生命周期和实验室发育的最新研究,以及其在遗传水平上的耐冷冻和耐干燥性,结合南极沙漠土壤的特殊生态系统,阐述其对于探索生命极限的意义。基于P.murrayi在南极麦克默多山谷土壤的生境分布,与其他南极自由生活线虫相比,P.murrayi喜欢相对较高的湿度和较低的盐度土壤生境。由于全球气候变暖,南极麦克默多山谷的温度和湿度不断增加,P.murrayi极可能成为南极沙漠中的主要陆生动物。通过对P.murrayi的研究,能够探索其适应和功能基因之间的新联系,这些基因在理解细胞对极端微环境的抗逆性方面有着至关重要的作用,具有长远的农业以及医学利用价值。未来对南极麦克默多山谷土壤环境压力的短期和长期响应的研究,有助于揭示细胞对环境干旱、寒冷的耐受和修复作用,探明生物进化与生态系统复杂性之间的关系,以及不同微环境在塑造更复杂系统群落中的作用。

Antarctic soil metazoa is one of the most valuable bio-resources on the earth.Its adaptation of extremely harsh soil habitats and ecological functions has always been one of the leading topics in evolution and soil ecology.Nematode Plectus murrayi is one of the dominant continental organisms only found in Antarctica,and it is merging as a model organism for studying on evolutionary biology in high stresses environment.This study aims to review the current studies of its phylogeny,distribution,life cycle and the development in the laboratory,as well as its freezing and desiccation tolerance on a genetic level.Compared to other Antarctic nematodes,P.murrayi prefers relatively higher moisture and lower salinity soil habitats,which might be consistent with its broad distribution in more productive habitats of Antarctica.Due to the temperature and humidity increasing in Antarctic McMurdo Dry Valleys(MDV),P.murrayi may become into the dominant continental animal in Antarctic deserts.By researching on P.murrayi,we hope to be able to explore new connections between its adaptation and functional genes that are responsible for stress tolerance and stoichiometric constraints(including the GRH and genomic streamlining).Based on studies of short-term and long-term responses of P.murrayi to environmental stresses in Antarctica,it is possible to reveal the relationship between the evolution and ecosystem complexity,as well as the role of elemental stoichiometry in shaping communities from more complex ecosystems.