Burg M G, Wu C F
Department of Biology, University of Iowa, Iowa City 52242.
Dev Biol. 1989 Feb;131(2):505-14. doi: 10.1016/s0012-1606(89)80021-1.
The formation and maintenance of the central projections of identified bristle mechanosensory neurons with altered excitability were examined in Drosophila mosaics. Two mutants, eag (ether à go-go) and Sh (Shaker), are known to increase excitability of both nerve and muscle cells and enhance synaptic transmission by affecting different types of K+ currents. The eag Sh double mutant produces a synergistic effect, resulting in a greatly increased level of spontaneous neuronal activity and extreme behavioral phenotypes. By constructing mosaic flies containing small patches of doubly mutant cuticle, it was possible to alter the excitability of only one or two identified sensory cells without affecting the surrounding tissue. In these mosaic flies, the doubly mutant sensory cells were more responsive to tactile stimulation. A CoCl2 backfilling technique was utilized in staining the sensory cell projections. Both qualitative and quantitative comparisons were made between projections of cells having normal and increased levels of excitability. The length, branching characteristics, and number of terminal varicosities were analyzed for each sensory cell projection. Results indicate that, at the light microscopy level, these characteristics were not obviously altered by an increased level of excitability.
在果蝇嵌合体中研究了兴奋性改变的特定刚毛机械感觉神经元的中枢投射的形成和维持。已知两种突变体，eag（ether à go-go）和Sh（Shaker），可增加神经和肌肉细胞的兴奋性，并通过影响不同类型的钾离子电流来增强突触传递。eag Sh双突变体产生协同效应，导致自发神经元活动水平大幅增加和极端行为表型。通过构建含有双突变表皮小斑块的嵌合果蝇，有可能仅改变一两个特定感觉细胞的兴奋性而不影响周围组织。在这些嵌合果蝇中，双突变感觉细胞对触觉刺激更敏感。采用CoCl2回填技术对感觉细胞投射进行染色。对兴奋性正常和增加的细胞投射进行了定性和定量比较。分析了每个感觉细胞投射的长度、分支特征和终末膨体数量。结果表明，在光学显微镜水平上，这些特征并未因兴奋性增加而明显改变。
