During cold acclimation fruit flies switch their feeding from yeast to plant food, however there are no robust molecular markers to monitor this in the wild. Drosophila melanogaster is a sterol auxotroph and relies on dietary sterols to produce lipid membranes, lipoproteins and molting hormones. We employed shotgun lipidomics to quantify eight major food sterols in total lipid extracts of heads and genital tracts of adult male and female flies. We found that their sterol composition is dynamic and reflective of fly diet in an organ-specific manner. Season-dependent changes observed in the organs of wild-living flies suggested that the molar ratio between yeast (ergosterol, zymosterol) and plant (sitosterol, stigmasterol) sterols is a quantifiable, generic and unequivocal marker of their feeding behavior suitable for ecological and environmental population-based studies. The enrichment of phytosterols over yeast sterols in wild-living flies at low temperatures is consistent with switching from yeast to plant diet and corroborates the concomitantly increased unsaturation of their membrane lipids.

中文翻译：

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甾醇作为果蝇的饮食标志。

在冷适应过程中，果蝇将其喂养方式从酵母转换为植物性食物，但是没有强大的分子标记可以在野外进行监测。果蝇（Drosophila melanogaster）是一种固醇营养缺陷型，依靠饮食固醇产生脂质膜，脂蛋白和蜕皮激素。我们采用shot弹枪脂质组学来定量成年雄蝇和雌蝇的头部和生殖道的总脂质提取物中的八种主要食物固醇。我们发现它们的固醇成分是动态的，并且以器官特异性方式反映了蝇食。在野外苍蝇器官中观察到的季节依赖性变化表明，酵母（麦角固醇，zymosterol）和植物（谷固醇，豆固醇）固醇之间的摩尔比是可量化的，它们的摄食行为的通用且明确的标记，适用于基于生态和环境人群的研究。在低温下，野生生活果蝇中植物甾醇比酵母固醇的富集与从酵母转换为植物饮食相一致，并证实了其膜脂的不饱和度随之增加。