Lipid molecules are organic compounds, insoluble in water, and based on carbon-carbon chains that form an integral part of biological cell membranes. As such, lipids are ubiquitous in life on Earth, which is why they are considered useful biomarkers for life detection in terrestrial environments. These molecules display effective membrane-forming properties even under geochemically hostile conditions that challenge most of microbial life, which grants lipids a universal biomarker character suitable for life detection beyond Earth, where a putative biological membrane would also be required. What discriminates lipids from nucleic acids or proteins is their capacity to retain diagnostic information about their biological source in their recalcitrant hydrocarbon skeletons for thousands of millions of years, which is indispensable in the field of astrobiology given the time span that the geological ages of planetary bodies encompass. This work gathers studies that have employed lipid biomarker approaches for paleoenvironmental surveys and life detection purposes in terrestrial environments with extreme conditions: hydrothermal, hyperarid, hypersaline, and highly acidic, among others; all of which are analogous to current or past conditions on Mars. Although some of the compounds discussed in this review may be abiotically synthesized, we focus on those with a biological origin, namely lipid biomarkers. Therefore, along with appropriate complementary techniques such as bulk and compound-specific stable carbon isotope analysis, this work recapitulates and reevaluates the potential of lipid biomarkers as an additional, powerful tool to interrogate whether there is life on Mars, or if there ever was.

中文翻译：

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与火星探索相关的陆地极端环境中脂质生物标志物的概述。

脂质分子是有机化合物，不溶于水，基于碳-碳链，构成生物细胞膜的组成部分。因此，脂质在地球上的生命中无处不在，这就是为什么它们被认为是陆地环境中生命检测的有用生物标志物。即使在挑战大多数微生物生命的地球化学恶劣条件下，这些分子也显示出有效的成膜特性，这赋予脂质一种通用的生物标志物特征，适用于地球以外的生命检测，而地球以外的地方也需要假定的生物膜。将脂质与核酸或蛋白质区分开来的是它们能够在其顽固的碳氢化合物骨架中保留有关其生物来源的诊断信息数亿年，鉴于行星体的地质年龄所涵盖的时间跨度，这在天体生物学领域是不可或缺的。这项工作收集了在具有极端条件的陆地环境中采用脂质生物标志物方法进行古环境调查和生命检测目的的研究：热液、超干旱、高盐度和高酸性等；所有这些都类似于火星上当前或过去的情况。尽管本综述中讨论的一些化合物可能是非生物合成的，但我们关注的是那些具有生物来源的化合物，即脂质生物标志物。因此，连同适当的补充技术，如批量和化合物特异性稳定碳同位素分析，这项工作概括并重新评估了脂质生物标志物作为额外的潜力，