![]() ![]() This collection of mutants, together with anatomical data on dendrites and axons, should begin to permit studies of dendrite diversity in a combined developmental and functional context, and also provide a foundation for understanding shared and distinct mechanisms that control axon and dendrite morphology. Several known loci, as well as putative novel mutations, were identified that contribute to sensory dendrite and/or axon patterning. For the latter, we screened the third chromosome at high resolution in vivo for mutations that affect class IV da neuron morphology. We have examined the effect of Robo family members on class-specific axon lamination, and have also taken a forward genetic approach to identify new genes involved in axon and dendrite development. We have identified a class-specific medial-lateral layering of axons in the central nervous system formed during embryonic development, which could allow different classes of da neurons to develop differential connectivity to second-order neurons. We found that multiple parameters of axon morphology, including dorsoventral position, midline crossing and collateral branching, correlate with dendritic morphological class. To begin to build a basis for linking dendrite structure and function in this genetic system, we analyzed da neuron axon projections in embryonic and larval stages. Drosophila dendritic arborization (da) sensory neurons display class-specific dendritic morphology with extensive coverage of the body wall. Here we show that dendritic arbors of adult Drosophila sensory neurons are rapidly reshaped from a radial shape to a lattice-like shape within 24 hr after eclosion. Dendrite severing is preceded by local breakdown of dendritic microtubules through PAR-1-mediated inhibition of Tau. Pruning dendrites are severed in their proximal regions, but how this spatial information is encoded is not clear. In addition, ecdysone activates the eukaryotic initiation factor 4E-binding protein (4E-BP) to inhibit cap-dependent translation initiation. Neurons establish diverse dendritic morphologies during development, and a major challenge is to understand how these distinct developmental programs might relate to, and influence, neuronal function. Drosophila sensory neurons prune their larval dendrites during metamorphosis. Dendrite pruning of Drosophila sensory neurons during metamorphosis is induced by the steroid hormone ecdysone through a transcriptional program. ![]()
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