Mensch Julián, Kreiman Lucas, Schilman Pablo E, Hasson Esteban, Renault David, Colinet Hervé
Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Ecología, Genética y Evolución, Laboratorio de Evolución, Buenos Aires, Argentina; CONICET - Universidad de Buenos Aires, Instituto de Ecología, Genética y Evolución de Buenos Aires (IEGEBA), Buenos Aires, Argentina.
Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Ecología, Genética y Evolución, Laboratorio de Evolución, Buenos Aires, Argentina; CONICET - Universidad de Buenos Aires, Instituto de Ecología, Genética y Evolución de Buenos Aires (IEGEBA), Buenos Aires, Argentina.
Comp Biochem Physiol A Mol Integr Physiol. 2021 Aug;258:110995. doi: 10.1016/j.cbpa.2021.110995. Epub 2021 May 25.
Temperate species, contrary to their tropical counterparts, are exposed not only to thermally variable environments with low temperatures but also to long winters. Different selective pressures may have driven divergent physiological adaptations in closely related species with different biogeographic origins. To survive unfavourable winter conditions, Drosophila species in temperate areas generally undergo a period of reproductive dormancy, associated with a cold-induced cessation of oogenesis and metabolic reorganization. This work aims to compare cold tolerance and metabolic signatures of cold-exposed females exhibiting different reproductive maturity status (mature and immature females) of four Drosophila species from tropical vs. temperate origins. We expected that the capacity for delayed reproduction of immature females could result in the redirection of the energy-related metabolites to be utilized for surviving the cold season. To do so, we studied an array of 45 metabolites using quantitative target GC-MS profiling. Reproductively immature females of temperate species showed the lower CT and the faster chill coma recovery time (i.e. the most cold-tolerant group). Principal component analysis captured differences across species, but also between reproductive maturity states. Notably, temperate species exhibited significantly higher levels of glucose, alanine, and gluconolactone than tropical ones. As proline and glycerol showed higher abundances in immature females of temperate species compared to the levels exhibited by the rest of the groups, we reasoned that glucose and alanine could serve as intermediates in the synthesis of these compatible solutes. All in all, our findings suggest that cold-exposed females of temperate species accumulate energy-related and protective metabolites (e.g. glycerol and proline) while delaying reproduction, and that these metabolites are relevant to cold tolerance even at modest concentrations.
与热带物种不同，温带物种不仅面临低温且温度多变的环境，还面临漫长的冬季。不同的选择压力可能促使具有不同生物地理起源的近缘物种产生了不同的生理适应性。为了在不利的冬季条件下生存，温带地区的果蝇物种通常会经历一段生殖休眠期，这与寒冷诱导的卵子发生停止和代谢重组有关。这项研究旨在比较来自热带和温带的四种果蝇处于不同生殖成熟状态（成熟和未成熟雌性）的雌性果蝇在冷暴露后的耐寒性和代谢特征。我们预计未成熟雌性果蝇延迟繁殖的能力可能会导致能量相关代谢物的重新定向，以用于度过寒冷季节。为此，我们使用定量目标气相色谱 - 质谱分析研究了一系列45种代谢物。温带物种的未成熟雌性果蝇表现出较低的低温致死温度和较快的冷昏迷恢复时间（即最耐寒的群体）。主成分分析不仅捕捉到了物种之间的差异，还捕捉到了生殖成熟状态之间的差异。值得注意的是，温带物种的葡萄糖、丙氨酸和葡萄糖酸内酯水平显著高于热带物种。由于与其他组相比，温带物种未成熟雌性果蝇中的脯氨酸和甘油含量更高，我们推测葡萄糖和丙氨酸可能是这些相容性溶质合成的中间体。总而言之，我们的研究结果表明，温带物种的冷暴露雌性果蝇在延迟繁殖的同时积累了能量相关和保护性代谢物（如甘油和脯氨酸），并且即使在适度浓度下，这些代谢物也与耐寒性相关。
