Cold adaptation increases rates of nutrient flow and metabolic plasticity during cold exposure in Drosophila melanogaster

Metabolic flexibility is an important component of adaptation to stressful environments, including thermal stress and latitudinal adaptation. A long history of population genetic studies suggest that selection on core metabolic enzymes may shape life histories by altering metabolic flux. However, the direct relationship between selection on thermal stress hardiness and metabolic flux has not previously been tested. We investigated flexibility of nutrient catabolism during cold stress in Drosophila melanogaster artificially selected for fast or slow recovery from chill coma (i.e. cold-hardy or -susceptible), specifically testing the hypothesis that stress adaptation increases metabolic turnover. Using 13C-labelled glucose, we first showed that cold-hardy flies more rapidly incorporate ingested carbon into amino acids and newly synthesized glucose, permitting rapid synthesis of proline, a compound shown elsewhere to improve survival of cold stress. Second, using glucose and leucine tracer...

代谢灵活性（metabolic flexibility）是生物应对各类胁迫环境的关键适应性组分，涵盖温度胁迫与纬度适应性演化。长期群体遗传学研究表明，对核心代谢酶的选择可通过改变代谢流塑造生物的生活史特征。然而，温度胁迫耐受性的定向选择与代谢流之间的直接关联，此前尚未得到验证。本研究以经过人工选育、可快速或缓慢从冷昏迷（chill coma）中恢复的黑腹果蝇（Drosophila melanogaster）——即耐寒或冷敏感品系——为研究对象，探究其在冷胁迫下的营养分解代谢灵活性，旨在验证“胁迫适应性可提升代谢周转速率”这一假说。借助13C标记葡萄糖（13C-labelled glucose）示踪技术，我们首先发现耐寒品系果蝇能够更快速地将摄入的碳源整合进入氨基酸与新合成的葡萄糖中，从而实现脯氨酸（proline）的快速合成——已有研究证实该化合物可提升生物的低温胁迫存活率。其次，我们利用葡萄糖与亮氨酸示踪剂……