Anduaga Ane Martin, Nagy Dora, Costa Rodolfo, Kyriacou Charalambos P
Department of Genetics and Genome Biology, University of Leicester, Leicester LE1 7RH, UK.
Department of Biology, University of Padova, Padova 35131, Italy.
J Insect Physiol. 2018 Feb-Mar;105:46-53. doi: 10.1016/j.jinsphys.2018.01.003. Epub 2018 Jan 12.
Unlike many insects where photoperiod per se induces diapause, reproductive arrest in Drosophila melanogaster adult females is observed at colder temperatures and can be enhanced by shorter photoperiods. Traditional experimental protocols raise flies at 25 °C from the larval stage and then the adults are placed at 12 °C for between 12 and 28 days. After 12 days diapause levels are usually higher than at 28 days, suggesting that the flies are in a cold induced quiescence, rather than a true diapause. By raising flies at more realistic lower temperatures, we observe quite dramatic and counter-intuitive effects on diapause, whose levels nevertheless correlate with various indices of cryoprotectant metabolites as well as resistance to chill shock. We also observe that photoperiodic effects are minimised when very small temperature oscillations associated with the light-dark incubator cycles are neutralised. Our results suggest that the reported photoperiodic component of fly diapause, at least in these strains, is mostly due to thermoperiodic rather than photoperiodic stimuli. In addition, the metabolite and chill shock analyses reveal that even by 12 days, flies are entering a state that is resistant to environmental stresses.
与许多昆虫不同，在这些昆虫中光周期本身会诱导滞育，而黑腹果蝇成年雌性的生殖停滞是在较低温度下观察到的，并且较短的光周期会增强这种停滞。传统的实验方案是从幼虫阶段开始在25°C饲养果蝇，然后将成虫置于12°C环境中12至28天。12天后的滞育水平通常高于28天后的，这表明果蝇处于冷诱导的静止状态，而不是真正的滞育。通过在更接近实际的较低温度下饲养果蝇，我们观察到滞育出现了相当显著且违反直觉的影响，但其水平仍与抗冻代谢物的各种指标以及对冷休克的抗性相关。我们还观察到，当与明暗培养箱循环相关的非常小的温度振荡被抵消时，光周期效应会降至最低。我们的结果表明，所报道的果蝇滞育的光周期成分，至少在这些品系中，主要是由于热周期而非光周期刺激。此外，代谢物和冷休克分析表明，即使在12天时，果蝇也正在进入一种对环境压力具有抗性的状态。
