Activity-independent prespecification of synaptic partners in the visual map of Drosophila
Activity-independent prespecification of synaptic partners in the visual map of Drosophila
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DOI：
10.1016/j.cub.2006.07.047
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发表时间：
2006-09-19
期刊：
影响因子：
9.2
通讯作者：
Bellen, Hugo J.
中科院分区：
文献类型：
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作者：
Hiesinger, P. Robin;Zhai, R. Grace;Bellen, Hugo J.
在迄今为止研究的所有系统中，突触伴侣和调节突触数量至少部分地是视觉地图形成过程中的活动依赖性过程[1 - 5]。在果蝇中，六个在视觉空间中观察同一点的光感受器必须被分类到称为盒的突触模块中，以形成视觉上正确的地图（6，7）。每个光感受器末端和盒的突触数量都受到精确调节[8 - 10]。然而，目前尚不清楚是否有活动依赖性机制或遗传编码的发育程序调节突触数量。我们对影响电位产生的突变体中的感光突触进行了大规模的定量超微结构分析（norpA，trp; trpl），神经递质释放（hdc，syt），囊泡内吞作用（synj），在光感受器靶向过程中特异性引导分子的运输（sec15），视觉图形成所需的特异性引导受体（Dlar，以及影响43个基因的57种其他新型突触突变体。值得注意的是，在所有这些突变体中，单个光感受器在每个突触前末端形成正确数量的突触，而与盒的组成无关。因此，我们的数据表明，每个感光细胞
Specifying synaptic partners and regulating synaptic numbers are at least partly activity-depen dent processes during visual map formation in all systems investigated to date [1-5]. In Drosophila, six photoreceptors that view the same point in visual space have to be sorted into synaptic modules called cartridges in order to form a visuotopically correct map (6, 7]. Synapse numbers per photoreceptor terminal and cartridge are both precisely regulated [8-10]. However, it is unknown whether an activity-dependent mechanism or a genetically encoded developmental program regulates synapse numbers. We performed a large-scale quantitative ultrastructural analysis of photoreceptor synapses in mutants affecting the generation of electrical potentials (norpA, trp;trpl), neurotransmitter release (hdc, syt), vesicle endocytosis (synj), the trafficking of specific guidance molecules during photoreceptor targeting (sec15), a specific guidance receptor required for visual map formation (Dlar, and 57 other novel synaptic mutants affecting 43 genes. Remarkably, in all these mutants, individual photoreceptors form the correct number of synapses per presynaptic terminal independently of cartridge composition. Hence, our data show that each photoreceptor