Denker Annette, Kröhnert Katharina, Rizzoli Silvio O
European Neuroscience Institute, Grisebachstr. 5, Göttingen 37077, Germany.
J Physiol. 2009 Jun 15;587(Pt 12):2919-26. doi: 10.1113/jphysiol.2009.170985. Epub 2009 Apr 29.
The synaptic vesicles are organized in distinct populations or 'pools': the readily releasable pool (the first vesicles released upon stimulation), the recycling pool (which maintains release under moderate stimulation) and the reserve pool (which is called into action only upon strong, often unphysiological stimulation). A major question in the field is whether the pools consist of biochemically different vesicles or whether the pool tag is a spatial one (with the recycling vesicles found next to the release sites, and the reserve ones farther away). A strong and stable spatial segregation has been proposed in the last decade in the Drosophila larval neuromuscular junction--albeit based solely on light microscopy experiments. We have tested here this hypothesis using electron microscopy (EM) photoconversion. We found the recycling and reserve pools to be thoroughly intermixed at the EM level, indicating that spatial location is irrelevant for the functional properties of the vesicle.
突触小泡被组织成不同的群体或“池”：易释放池（刺激时首先释放的小泡）、循环池（在适度刺激下维持释放）和储备池（仅在强烈的、通常是非生理性刺激时才起作用）。该领域的一个主要问题是，这些池是由生化性质不同的小泡组成，还是池标签是空间性的（循环小泡位于释放位点附近，储备小泡则更远）。在过去十年中，有人提出在果蝇幼虫神经肌肉接头处存在强烈而稳定的空间隔离——尽管这仅仅基于光学显微镜实验。我们在这里使用电子显微镜（EM）光转化测试了这一假设。我们发现在电子显微镜水平上，循环池和储备池完全混合在一起，这表明空间位置与小泡的功能特性无关。
