近日，瑞士洛桑大学Richard Benton等研究人员合作发现，昼夜节律可塑性通过神经肽基因的调控变化演化。相关论文于2024年10月16日在线发表在《自然》杂志上。

研究人员将黑腹果蝇（Drosophila melanogaster）与赤道生态特化物种塞舌尔果蝇（Drosophila sechellia）进行比较。后者经历的光周期变化最小，以探讨昼夜节律可塑性演化的机制。塞舌尔果蝇已经失去了在长光周期下推迟其傍晚活动峰值的能力。通过筛选黑腹果蝇和塞舌尔果蝇杂交体中的昼夜节律突变体，研究人员发现神经肽色素分散因子（Pdf）在此能力丧失中起到了一定作用。Pdf表现出物种特异性的时间表达，部分原因是顺式调控的差异。

在黑腹果蝇中使用物种特异性的Pdf调控序列进行RNA干扰和补救实验表明，该神经肽的表达调控影响行为可塑性的程度。Pdf调控区域在塞舌尔果蝇和来自不同纬度的黑腹果蝇种群中显示出选择信号。研究人员提供的证据表明，可塑性在较高纬度地区为黑腹果蝇提供了选择优势，而塞舌尔果蝇在其范围之外可能因减少交配成功率而承受适应性成本。该研究表明，这个神经肽基因是昼夜节律可塑性演化的热点位点，可能促进了黑腹果蝇的全球分布和塞舌尔果蝇的特化进程。

据悉，包括世界性分布的果蝇在内的许多生物表现出昼夜节律的可塑性，随着黎明和黄昏时间的变化调整它们的活动。然而，这种行为如何演化尚不清楚。

附：英文原文

Title: Circadian plasticity evolves through regulatory changes in a neuropeptide gene

Author: Shahandeh, Michael P., Abuin, Liliane, Lescuyer De Decker, Lou, Cergneux, Julien, Koch, Rafael, Nagoshi, Emi, Benton, Richard

Issue&Volume: 2024-10-16

Abstract: Many organisms, including cosmopolitan drosophilids, show circadian plasticity, varying their activity with changing dawn–dusk intervals1. How this behaviour evolves is unclear. Here we compare Drosophila melanogaster with Drosophila sechellia, an equatorial, ecological specialist that experiences minimal photoperiod variation, to investigate the mechanistic basis of circadian plasticity evolution2. D. sechellia has lost the ability to delay its evening activity peak time under long photoperiods. Screening of circadian mutants in D. melanogaster/D. sechellia hybrids identifies a contribution of the neuropeptide pigment-dispersing factor (Pdf) to this loss. Pdf exhibits species-specific temporal expression, due in part to cis-regulatory divergence. RNA interference and rescue experiments in D. melanogaster using species-specific Pdf regulatory sequences demonstrate that modulation of this neuropeptide’s expression affects the degree of behavioural plasticity. The Pdf regulatory region exhibits signals of selection in D. sechellia and across populations of D. melanogaster from different latitudes. We provide evidence that plasticity confers a selective advantage for D. melanogaster at elevated latitude, whereas D. sechellia probably suffers fitness costs through reduced copulation success outside its range. Our findings highlight this neuropeptide gene as a hotspot locus for circadian plasticity evolution that might have contributed to both D. melanogaster’s global distribution and D. sechellia’s specialization.

DOI: 10.1038/s41586-024-08056-x

Source: https://www.nature.com/articles/s41586-024-08056-x