Analysis of Synaptic Transmission using Molecular Genetics

i）神经元突触泡蛋白（n-syb）对于突触传递的作用。我们研究了缺乏n-syb的果蝇胚胎的突触传递。没有观察到神经诱发的突触电流，但很容易检测到微型突触电流（mSCs）。mSCs的频率是Ca^<2+>依赖性的。在缺乏外部Ca^<2+>的情况下，环磷酸腺苷并没有增加mSCs的频率。ii）由环磷酸腺苷/PKA介导的两条独立的途径增强果蝇神经肌肉接头处自发性递质释放。我们证明，cAMP增强突触传递的n-syb依赖和独立的方式。iii）代谢型谷氨酸受体的激活增强突触传递在果蝇神经肌肉接头。在无Ca^2+的生理盐水中喷入谷氨酸盐可增加自发突触电流的频率。这种反应被代谢型谷氨酸受体拮抗剂阻断。腺苷酸环化酶激活剂，如forskolin，模仿glu的作用。 ...更多信息 塔马特。谷氨酸的作用被腺苷酸环化酶抑制剂阻断。在外部Ca^<2+>存在的情况下，代谢型谷氨酸受体的激动剂增强了突触传递。在幼虫果蝇神经肌肉接头内源性谷氨酸释放在终端通过涉及cAMP的过程增强突触传递。iv）筛选突触缺陷揭示了一个位点参与突触前和突触后功能在果蝇胚胎。分离到一种新的突变体，其在突触传递中具有中度缺陷。该基因被克隆，并发现是相同的，最近报道的基因，apontic，这可能会产生一个转录因子。v）两个突触囊泡池被确定在果蝇突触前末端。外向/内向循环池（易释放池）位于突触末梢的外周，并在低频刺激期间维持突触传递，而储备池中的囊泡在高频刺激期间被释放。外/内循环池的大小与突触的量子含量成比例相关。超微结构与神经肌肉接头发育相关。transmission.vi电镜观察突触形成早期神经肌肉接头的超微结构。少

i) Role of neuronal synaptobrevin (n-syb) for synaptic transmission. We examined synaptic transmission in Drosophila embryos lacking n-syb. No nerve-evoked synaptic currents were observed, but miniature synaptic currents (mSCs) were readily detected. The frequency of mSCs was Ca^<2+> dependent. Cyclic AMP did not increase the frequency of mSCs in the absence of external Ca^<2+>.ii) Two independent pathways mediated by cAMP/PKA enhance spontaneous transmitter release at Drosophila neuromuscular junctions. We demonstrated that cAMP enhances synaptic transmission in the n-syb dependent and independent ways.iii) Activation of metabotropic glutamate receptors enhances synaptic transmission at the Drosophila neuromuscular junction. Puff application of glutamate in Ca^<2+> -free saline increased the frequency of spontaneous synaptic currents. This response was blocked by antagonists of metabotropic glutamate receptors. Adenylyl cyclase activators, such as forskolin, mimicked the effect of glu … More tamate. The effect of glutamate was blocked by an inhibitor of adenylyl cyclase. In the presence of external Ca^<2+>, an agonist of metabotropic glutamate receptors enhanced synaptic transmission. At the larval Drosophila neuromuscular junction endogeneous glutamate released at the terminal potentiates synaptic transmission via a process involving cAMP.iv) Screening for synaptic defects revealed a locus involved in presynaptic and postsynaptic functions in Drosophila embryos. A new mutant was isolated which has moderate defects in synaptic transmission. The gene was cloned and found to be identical to a recently reported gene, apontic, which presumably produces a transcription factor.v) Two synaptic vesicle pools were identified at the Drosophila presynaptic terminal. The exo/endo cycling pool (readily releasable pool) is in the periphery of synaptic terminals and maintains synaptic transmission during low frequency stimulation, while vesicles in the reserve pool are released during high frequency stimulation. The size of the exo/endo cycling pool is proportionately related to the quantal content of synaptic transmission.vi) Ultrastructure correlates of neuromuscular junction development. Ultrastructures of neuromuscular junction was examined in EM during early stages of synapse formation. Less