Canal I, Fariñas C I, Gho M, Ferrús A
Instituto Cajal, CSIC, Madrid, Spain.
Eur J Neurosci. 1994 Sep 1;6(9):1423-31. doi: 10.1111/j.1460-9568.1994.tb01004.x.
The role of the pre- and postsynaptic cells in determining the number of synapses has been investigated in retina mosaics of the gigas (gig) mutant of Drosophila. Mutant photoreceptors are two to three times larger than those of the wild type, while adjacent cells in the mosaic retina and the lamina are normal in size. Serial electron microscope reconstructions of mosaic lamina cartridges show that gig photoreceptors establish more synapses upon lamina neurons than the normal photoreceptors do. By contrast, the number of feedback synapses that lamina neurons make onto gig photoreceptors does not increase. The increment in the number of synapses correlates positively with the increment of presynaptic cell membrane, resulting in constancy of synapse density. The phototactic response of flies bearing a gig eye is abnormal, indicating that the extra synapses are functional.
在果蝇巨眼（gig）突变体的视网膜镶嵌体中，研究了突触前和突触后细胞在决定突触数量方面的作用。突变体光感受器比野生型的大两到三倍，而镶嵌视网膜和神经节层中的相邻细胞大小正常。对镶嵌神经节层盒进行的连续电子显微镜重建显示，gig光感受器在神经节层神经元上建立的突触比正常光感受器更多。相比之下，神经节层神经元在gig光感受器上形成的反馈突触数量并未增加。突触数量的增加与突触前细胞膜的增加呈正相关，从而导致突触密度保持恒定。具有gig眼的果蝇的趋光反应异常，表明额外突触具有功能。
