| Budget Amount *help |
¥20,500,000 (Direct Cost: ¥20,500,000)
Fiscal Year 2001: ¥5,400,000 (Direct Cost: ¥5,400,000)
Fiscal Year 2000: ¥6,200,000 (Direct Cost: ¥6,200,000)
Fiscal Year 1999: ¥8,900,000 (Direct Cost: ¥8,900,000)
|
|---|
| Research Abstract |
The neural network in the microbrain is quite precise at the single cell level. We have investigated how such elaborated systems are formed under genetic control, focusing on the synapse formation. Using Drosophila, in which many genetic tools are available, we have examined the subcellular localizations of several proteins that are involved in synaptic development by immunoelectron microscopy. And by the ultrastructural analysis of genetic mutants or ectopic expression experiments, we could get following results concerning the genetic mechanisms of the cell-specific formation of microbrain synapses.
1. Analysis of proteins involved in synapse formation (HIG, SIF, TRIO etc.) : HIG was localized in synaptic clefts. And the HIG expression experiments in mutant pupae indicated that it is required for synapse formation. SIF and TRIO are GTP-GDP exchange factors, and they were shown to regulate synapse morphogenesis. SIF localized in the pre-synaptic peri-active zone, and appeared to function in coordination with Fas2. TRIO was distributed in all regions of a neuron, and was shown to be involved in axonal elongation.
2. Ultrastructural analysis of identified synapses by single cell labeling :
(1) By crossing Ga14 enhancer trap lines with a UAS-WGA line, or a UAS-GFP or a UAS-CD8 : : GFP line, we could identified synaptic terminal of single cells in the electron microscope.
(2) By crossing GAL4 enhancer trap lines and a UAS-gap-GFP line we demonstrated that the filopodia elongated from growth cones and target cells intermingle each other and increase adhesional structures, using fluorescence microscopy and electron microscopy. And, the ectopic expression of target recognition molecules such as Fas3 and Toll, indicated that this process is mediated by these molecules.
|
