Lipid homeostasis is essential for insects to maintain phospholipid (PL)-based membrane integrity and to provide on-demand energy supply throughout life. Triacylglycerol (TAG) is the major lipid class used for energy production and is stored in lipid droplets, the universal cellular fat storage organelles. Accumulation and mobilization of TAG are strictly regulated since excessive accumulation of TAG leads to obesity and has been correlated with adverse effects on health- and lifespan across phyla. Little is known, however, about when during adult life and why excessive storage lipid accumulation restricts lifespan. We here used genetically obese Drosophila mutant males, which were all shown to be short-lived compared to control males and applied single fly mass spectrometry-based lipidomics to profile TAG, diacylglycerol and major membrane lipid signatures throughout adult fly life from eclosion to death. Our comparative approach revealed distinct phases of lipidome remodeling throughout aging. Quantitative and qualitative compositional changes of TAG and PL species, which are characterized by the length and saturation of their constituent fatty acids, were pronounced during young adult life. In contrast, lipid signatures of adult and senescent flies were remarkably stable. Genetically obese flies displayed both quantitative and qualitative changes in TAG species composition, while PL signatures were almost unaltered compared to normal flies at all ages. Collectively, this suggests a tight control of membrane composition throughout lifetime largely uncoupled from storage lipid metabolism. Finally, we present first evidence for a characteristic lipid signature of moribund flies, likely generated by a rapid and selective storage lipid depletion close to death. Of note, the analytical power to monitor lipid species profiles combined with high sensitivity of this single fly lipidomics approach is universally applicable to address developmental or behavioral lipid signature modulations of importance for insect life.

脂质稳态对于昆虫维持基于磷脂 (PL) 的膜完整性和在整个生命过程中提供按需能源供应至关重要。三酰甘油 (TAG) 是用于产生能量的主要脂质类，储存在脂滴中，脂滴是通用的细胞脂肪储存细胞器。TAG 的积累和动员受到严格监管，因为 TAG 的过度积累会导致肥胖，并且与对整个门的健康和寿命的不利影响相关。然而，关于成年期何时以及为什么过多的储存脂质积累会限制寿命，我们知之甚少。我们在这里使用了遗传肥胖的果蝇突变雄性，与对照雄性相比，它们都被证明寿命短，并应用基于单蝇质谱的脂质组学来分析从羽化到死亡的整个成年果蝇生命中的 TAG、甘油二酯和主要膜脂特征。我们的比较方法揭示了整个衰老过程中脂质组重塑的不同阶段。TAG 和 PL 物种的数量和质量组成变化，其特征在于其组成脂肪酸的长度和饱和度，在年轻的成年生活中很明显。相比之下，成年和衰老果蝇的脂质特征非常稳定。遗传肥胖的果蝇在 TAG 物种组成上显示出数量和质量的变化，而与所有年龄的正常果蝇相比，PL 特征几乎没有改变。总的来说，这表明在整个生命周期中严格控制膜成分，很大程度上与储存脂质代谢脱钩。最后，我们提出了垂死果蝇的特征性脂质特征的第一个证据，这可能是由接近死亡的快速和选择性储存脂质消耗产生的。值得注意的是，监测脂质种类概况的分析能力与这种单蝇脂质组学方法的高灵敏度相结合，普遍适用于解决对昆虫生命重要的发育或行为脂质特征调制。