Heterogeneity in synaptic transmission along a Drosophila larval motor axon
Heterogeneity in synaptic transmission along a Drosophila larval motor axon
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DOI：
10.1038/nn1526
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发表时间：
2005-09-01
影响因子：
25
通讯作者：
Isacoff, EY
中科院分区：
文献类型：
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作者：
Guerrero, G;Reiff, DF;Isacoff, EY
在黑腹果蝇幼虫神经肌肉接头（NMJ），运动神经元从30 - 100个终扣释放谷氨酸到它所支配的肌肉上。传输强度如何在NMJ的终扣之间分布是未知的。为了解决这个问题，我们创建了synapcam，这是Ca 2+报告者Cameleon的一个版本。Synapcam定位于突触后末梢，并通过谷氨酸受体（GluRs）以单脉冲和单终止分辨率选择性地报告Ca 2+内流。GluR为基础的Ca 2+信号是均匀的，在一个给定的连接（即，一个给定的终末/突触后终端对），但不同的NMJ连接之间的显着差异。沿沿着轴突分支，从弱近端连接到强远端连接，观察到一个陡峭的梯度的传输强度。突触前成像显示出匹配的轴突梯度，具有较高的Ca 2+内流和胞吐在远端终扣。结果表明，传递强度主要是在突触前决定的单个扣的水平，可能是由一个或多个因素存在的梯度。
At the Drosophila melanogaster larval neuromuscular junction (NMJ), a motor neuron releases glutamate from 30 - 100 boutons onto the muscle it innervates. How transmission strength is distributed among the boutons of the NMJ is unknown. To address this, we created synapcam, a version of the Ca2+ reporter Cameleon. Synapcam localizes to the postsynaptic terminal and selectively reports Ca2+ influx through glutamate receptors (GluRs) with single-impulse and single-bouton resolution. GluR-based Ca2+ signals were uniform within a given connection ( that is, a given bouton/postsynaptic terminal pair) but differed considerably among connections of an NMJ. A steep gradient of transmission strength was observed along axonal branches, from weak proximal connections to strong distal ones. Presynaptic imaging showed a matching axonal gradient, with higher Ca2+ influx and exocytosis at distal boutons. The results suggest that transmission strength is mainly determined presynaptically at the level of individual boutons, possibly by one or more factors existing in a gradient.