Disruption of synaptic transmission or clock-gene-product oscillations in circadian pacemaker cells of Drosophila cause abnormal behavioral rhythms
Disruption of synaptic transmission or clock-gene-product oscillations in circadian pacemaker cells of Drosophila cause abnormal behavioral rhythms
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DOI：
10.1002/(sici)1097-4695(20000605)43:3
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发表时间：
2000-06-05
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影响因子：
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通讯作者：
Hall, JC
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文献类型：
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作者：
Kaneko, M;Park, JH;Hall, JC
为了研究表达时钟基因的神经元的功能，破伤风毒素轻链(TeTxLC)，它阻断化学突触传递？在时钟基因周期(PER)和永恒(TIM)启动子的控制下表达，每个启动子都融合到GAL4编码序列。虽然TeTxLC没有在总体水平上影响时钟基因产物的循环，但它扰乱了成年果蝇的节律行为。在恒定的黑暗中，表达活性TeTxLC的果蝇与表达非活性毒素的对照组相比，节律性果蝇的比例减少，表达TeTxLC的果蝇的行为与光：暗周期的同步性低于对照组。为了确定哪些神经元负责这些对行为的影响，这种毒素也在PER/TIM表达的侧向起搏神经元的限制性亚群中表达，方法是在一个驱动器的控制下表达TeTxLC，在该驱动器中，GAL L编码的序列与色素分散因子(Pdf)基因的启动子融合。PDF-gal4驱动的TeTxLC的表达对行为节律的影响相对较小，这意味着除pdf表达的外侧神经元外，PER/TIM神经元参与了节律行为的产生。在另一组实验中，周期基因产物在PER-Gal4或TIM-Gal4的控制下表达。这导致了许多脑细胞中PER蛋白水平的增加和生物发光周期的减少，特别是在TIM-Gal4影响PER表达的情况下。这表明转录反馈环路被破坏，这是果蝇昼夜节律背后振荡机制的一部分。与这一分子缺陷相一致的是，在TIM-Gal4控制下表达PER的DIE中，处于持续黑暗中的节律性个体的比例低于正常，他们在光中的行为：暗周期是异常的。(C)2000 John Wiley&Sons，Inc.
To study the function of clock-gene-expressing neurons, the tetanus-toxin light chain (TeTxLC), which blocks chemical synaptic transmission? was expressed under the control of promoters of the clock genes period (per) and timeless (tim), each fused to GAL4-encoding sequences. Although TeTxLC did not affect cycling of a clock-gene product at the gross level, it disrupted the rhythmic behavior of adult Drosophila. In constant darkness, the proportion of rhythmic flies was reduced in flies expressing active TeTxLC compared to controls, including those expressing inactive toxin, The behavior of TeTxLC-expressing flies was less synchronized to light:dark cycles than that of controls. To determine which neurons are responsible for these effects on behavior, the toxin was also expressed in restricted subsets of per/tim-expressing, laterally located pacemaker neurons by expressing TeTxLC under the control of a driver in which GAL l-encoding sequences are fused to the promoter of the pigment dispersing factor (pdf) gene. pdf-gal4-driven TeTxLC expression had relatively little effect on behavioral rhythms, implying that per/tim neurons other than pdf-expressing lateral neurons participate in the generation of rhythmic behavior, In another set of experiments, period gene products were expressed under the control of per-gal4 or tim-gal4. This resulted in an increased level of PER protein in many brain cells and reduction of bioluminescence cycling reported by a per-luciferase transgene, especially in the case of per expression affected by tim-gal4. This indicates a disruption of the transcriptional feedback loop that is a part of the oscillatory mechanism underlying Drosophila's circadian rhythms. Consistent with this molecular defect, the proportion of rhythmic individuals in constant darkness was subnormal in dies expressing PER under the control of tim-gal4 and their behavior in light:dark cycles was abnormal. (C) 2000 John Wiley & Sons, Inc.