Blocking synaptic transmission with tetanus toxin light chain reveals modes of neurotransmission in the PDF-positive circadian clock neurons of Drosophila melanogaster
Blocking synaptic transmission with tetanus toxin light chain reveals modes of neurotransmission in the PDF-positive circadian clock neurons of Drosophila melanogaster
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用破伤风毒素轻链阻断突触传递揭示了果蝇 PDF 阳性生物钟神经元的神经传递模式
DOI：
10.1016/j.jinsphys.2011.06.004
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发表时间：
2011
影响因子：
2.2
通讯作者：
Yujiro
中科院分区：
文献类型：
--
作者：
Umezaki;Yujiro
黑腹果蝇的昼夜运动节律是由大约150个时钟神经元组成的神经元回路控制的，这些神经元大致分为7组。在神经回路中，一组表达色素分散因子（PDF）的神经元在组织起搏系统中起着重要作用。近年来的研究表明，PDF阳性神经元中也表达除PDF外的未知化学神经递质（UNT）。为了探索其在昼夜节律起搏器中的作用，我们研究了pdf-Gal4/UAS-TNT转基因果蝇的昼夜运动节律，其中表达的破伤风毒素轻链（TNT）阻断了pdf-Gal4阳性神经元的化学突触传递。在持续黑暗（DD）条件下，果蝇表现出自由奔跑的节奏，与野生型果蝇相似，但与pdf零突变体有显著差异。然而，在恒定光照条件下，它们往往表现出具有短周期和长周期成分的复杂节律。因此，UNT可能参与生物钟网络中的突触传递，LL导致其释放导致心律失常。免疫细胞化学表明，LL诱导了转基因果蝇部分pdf阳性和pdf阴性时钟神经元在TIMELESS （TIM）循环中的相分离。这些结果表明，PDF和UNT在果蝇生物钟中都起着重要的作用，而LL单独激活PDF通路会通过一些生物钟神经元之间的不同步振荡导致复杂的运动节律。
Circadian locomotor rhythms of Drosophila melanogaster are controlled by a neuronal circuit composed of approximately 150 clock neurons that are roughly classified into seven groups. In the circuit, a group of neurons expressing pigment-dispersing factor (PDF) play an important role in organizing the pacemaking system. Recent studies imply that unknown chemical neurotransmitter(s) (UNT) other than PDF is also expressed in the PDF-positive neurons. To explore its role in the circadian pacemaker, we examined the circadian locomotor rhythms of pdf-Gal4/UAS-TNT transgenic flies in which chemical synaptic transmission in PDF-positive neurons was blocked by expressed tetanus toxin light chain (TNT). In constant darkness (DD), the flies showed a free-running rhythm, which was similar to that of wild-type flies but significantly different from pdf null mutants. Under constant light conditions (LL), however, they often showed complex rhythms with a short period and a long period component. The UNT is thus likely involved in the synaptic transmission in the clock network and its release caused by LL leads to arrhythmicity. Immunocytochemistry revealed that LL induced phase separation in TIMELESS (TIM) cycling among some of the PDF-positive and PDF-negative clock neurons in the transgenic flies. These results suggest that both PDF and UNT play important roles in the Drosophila circadian clock, and activation of PDF pathway alone by LL leads to the complex locomotor rhythm through desynchronized oscillation among some of the clock neurons.