In some insects, repeated cold stresses, characterized by warm periods that interrupt a sustained cold period, have been found to yield survival benefits over continuous cold stresses, but at the cost of reproduction. During a cold stress, chill susceptible insects like Drosophila melanogaster suffer from a loss of ion and water balance, and the current model of recovery from chilling posits that re-establishment of ion homeostasis begins upon return to a warm environment, but that it takes minutes to hours for an insect to fully restore homeostasis. Following this ionoregulatory model of chill coma recovery, we predicted that the longer the duration of the warm periods between cold stresses, the better a fly will endure a subsequent chill coma event and the more likely they will be to survive. We also predicted, however, that this recovery may lead to reduced fecundity, possibly due to allocation of energy reserves away from reproduction. Here, female D.melanogaster were treated to a long continuous cold stress (25 h at 0 °C), or experienced the same total time in the cold with repeated short (15 min), or long (120 min) breaks at 22 °C. We found that warm periods in general improved survival outcomes, and individuals that recovered for more time in between cold periods had significantly lower rates of injury, faster recovery from chill coma, and produced greater, rather than fewer, offspring. These improvements in chill tolerance were associated with mitigation of ionoregulatory collapse, as flies that experienced either short or long warm periods better maintained low hemolymph [K+]. Thus, warm periods that interrupt cold periods improve cold tolerance and fertility in D. melanogaster females relative to a single sustained cold stress, potentially because this time allows for recovery of ion and water homeostasis.

中文翻译：

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反复寒冷胁迫下的温暖时期可保护果蝇免受离子调节失调，冷害和生殖缺陷。

在某些昆虫中，发现反复的冷胁迫（其特征在于温暖的时期会中断持续的寒冷时期）相对于连续的寒冷胁迫具有生存优势，但以繁殖为代价。在寒冷胁迫下，易感病的昆虫（如黑腹果蝇）会遭受离子和水平衡的损失，目前从冷库恢复的模型认为，离子稳态的重建是在回到温暖的环境后开始的，但需要几分钟的时间一个昆虫要花几个小时才能完全恢复体内平衡。遵循这种冷战昏迷恢复的电离模型，我们预测冷应激之间温暖期的持续时间越长，苍蝇越能忍受随后的冷战昏迷事件，并且它们存活的可能性就越大。但是，我们也预测到 这种恢复可能导致繁殖力降低，这可能是由于能量储备的分配远离了繁殖。在这里，雌性D.melanogaster经过长时间连续的冷应激处理（在0°C下25 h），或者在寒冷下经历了相同的总时间，反复短暂（15分钟），或者在22°下长时间休息（120 min） C。我们发现，温暖的时期总体上改善了生存结果，并且在寒冷的时期之间恢复更多时间的个体受伤率明显降低，从寒冷昏迷中恢复得更快，并且产生的后代更大而不是更少。耐寒性的这些提高与离子调节失调的缓解有关，因为经历过短时或长时温暖的果蝇都能更好地维持低血淋巴[K +]。从而，