Department of Neurobiology and Physiology, Northwestern University, Evanston, IL 60208, USA.
Curr Biol. 2010 Apr 13;20(7):591-9. doi: 10.1016/j.cub.2010.02.056. Epub 2010 Apr 1.
Daily behaviors in animals are determined by the interplay between internal timing signals from circadian clocks and environmental stimuli such as light. How these signals are integrated to produce timely and adaptive behavior is unclear. The fruit fly Drosophila exhibits clock-driven activity increases that anticipate dawn and dusk and free-running rhythms under constant conditions. Flies also respond to the onset of light and dark with acute increases in activity.
Mutants of a novel ion channel, narrow abdomen (na), lack a robust increase in activity in response to light and show reduced anticipatory behavior and free-running rhythms, providing a genetic link between photic responses and circadian clock function. We used tissue-specific rescue of na to demonstrate a role for approximately 16-20 circadian pacemaker neurons, a subset of the posterior dorsal neurons 1 (DN1(p)s), in mediating the acute response to the onset of light as well as morning anticipatory behavior. Circadian pacemaker neurons expressing the neuropeptide PIGMENT-DISPERSING FACTOR (PDF) are especially important for morning anticipation and free-running rhythms and send projections to the DN1(p)s. We also demonstrate that DN1(p)Pdfr expression is sufficient to rescue, at least partially, Pdfr morning anticipation defects as well as defects in free-running rhythms, including those in DN1 molecular clocks. Additionally, these DN1 clocks in wild-type flies are more strongly reset to timing changes in PDF clocks than other pacemaker neurons, suggesting that they are direct targets.
Taking these results together, we demonstrate that the DN1(p)s lie at the nexus of PDF and photic signaling to produce appropriate daily behavior.
动物的日常行为是由生物钟内部的时间信号与环境刺激（如光）之间的相互作用决定的。这些信号如何整合以产生及时和适应性的行为尚不清楚。果蝇表现出时钟驱动的活动增加，以预测黎明和黄昏，并在恒定条件下自由运行节律。苍蝇也会对光和暗的开始做出急性活动增加的反应。
一种新型离子通道狭窄腹部（na）的突变体对光的反应缺乏强烈的活性增加，表现出减少的预期行为和自由运行节律，为光反应和生物钟功能之间提供了遗传联系。我们使用组织特异性拯救 na 来证明大约 16-20 个生物钟起搏器神经元的作用，这是后部背神经元 1（DN1（p）s）的一部分，在介导对光开始的急性反应以及早晨预期行为中起作用。表达神经肽色素分散因子（PDF）的生物钟起搏器神经元对早晨的预期和自由运行节律特别重要，并向 DN1（p）s发送投射。我们还证明，DN1（p）Pdfr 的表达足以至少部分挽救 Pdfr 早晨预期缺陷以及自由运行节律缺陷，包括 DN1 分子钟缺陷。此外，与其他起搏器神经元相比，这些野生型果蝇中的 DN1 时钟在 PDF 时钟计时变化方面的重置更为强烈，这表明它们是直接靶点。
综合这些结果，我们证明 DN1（p）s位于 PDF 和光信号的交汇点，以产生适当的日常行为。
