Morphologycal analysses of the neural components of the input and output pathways involved in the Drosophila circadian system, with special reference to the cholinergic neurons.

在Drasophila中，各种证据表明，日常运动节律的昼夜节律起搏器位于位于延髓前皮中称为“侧神经元”（LN）的细胞中。然而，人们对将这些起搏细胞与行为节律联系起来的神经通路知之甚少。为了确定果蝇昼夜节律钟系统的输入和输出途径的神经成分，我们已经调查了大脑使用免疫细胞化学技术，特别是与胆碱能神经元。用抗果蝇胆碱乙酰转移酶（ChAT）单克隆抗体染色复眼后缘的一组视网膜外光感受器，称为“视神经”。从延髓出现的轴突终止于前髓质的区域，在那里可能的LNs的树突领域驻留。LN免疫反应的抗体对果蝇nAChR，这意味着胆碱能输入LN。这些间接证据表明， ...更多信息 参与了一个输入途径，有助于昼夜节律的夹带。携带由ChAT cDNA与1.2 kb的顺式调节序列组成的转基因的转化苍蝇表现出明显减少的ChAT表达的特定子集的胆碱能神经元，如终止于远端区域的延髓，在那里的静脉曲张的输出纤维的LN驻留的神经元。形态学研究表明，LN静脉曲张的髓质是显着大于在野生型苍蝇的转化体。转化体进入光：暗循环，并表现出具有早晨和晚上峰值的双峰运动活动模式，如对照果蝇（白色）。当照明水平低时（即，0.24 lux）时，转化体显示出不寻常的单噬运动活性，其仅发生在整个光照期，与对照中的双峰活性相反。这些观察结果表明，ChAT表达的缺陷导致转化体中的异常运动节律。少

In Drasophila, various lines of evidence suggest that the circadian pacemakers for daily locomotor rhythms reside in the cells called "lateral neurons" (LNs) lying in the anterior rind of the medulla. However, little is known about the neural pathways linking these pacemaker cells to behavioral rhythms. To identify the neural components of the input and output pathways of the Drosophila circadian clock system, we have surveyed the brain using immunocytochemical techniques, especially with reference to cholinergic neurons. A monoclonal antibody against Drosophila choline acetyltransferase (ChAT) stained a group of extraretinal photoreceptors at the posterior margin of the compound eye, which is called the "eyelet". The axons emerging from the eyelet terminated in the region of the anterior medulla, where the possible dendritic field of LNs resides. LNs were immunoreactive to an antibody against Drosophila nAChR, implying cholinergic input to LNs. This circumstantial evidence suggests th … More at the eyelet is involved in an input pathway contributing to circadian entrainment. Transformed flies carrying the transgene composed of ChAT cDNA with 1.2 kb of the cis-regulatory sequence showed obviously reduced ChAT expression in specific subsets of cholinergic neurons, such as the neurons terminating in the distal region of the medulla, where the varicosity of the output fibers of LNs resides. A morphometric study revealed that LN varicosity in the medulla was -significantly larger in the transformants than in the wild-type flies. The transformants entrained to light : dark cycles, and exhibited a double-peaked locomotor activity pattern with morning and evening peaks, as did control flies (white). When the illumination level was low (I.e., 0.24 lux), the transformants showed unusual monophagic locomotor activity exclusively occurring during the entire light phase, in contrast to double-peaked activity in the controls. These observations suggest that defects in ChAT expression resulted in the extraordinary locomotor rhythms in the transformants. Less