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Visualization of the Axonal Projection Pattern of Embryonic Motor Neurons in Drosophila
Published on: June 16, 2017
Glial and neuronal Semaphorin signaling instruct the development of a functional myotopic map for Drosophila walking
Durafshan Sakeena Syed1, Swetha B M Gowda1,2, O Venkateswara Reddy1
1National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India.
Abstract:
Motoneurons developmentally acquire appropriate cellular architectures that ensure connections with postsynaptic muscles and presynaptic neurons. In Drosophila, leg motoneurons are organized as a myotopic map, where their dendritic domains represent the muscle field. Here, we investigate mechanisms underlying development of aspects of this myotopic map, required for walking. A behavioral screen identified roles for Semaphorins (Sema) and Plexins (Plex) in walking behavior. Deciphering this phenotype, we show that PlexA/Sema1a mediates motoneuron axon branching in ways that differ in the proximal femur and distal tibia, based on motoneuronal birth order. Importantly, we show a novel role for glia in positioning dendrites of specific motoneurons; PlexB/Sema2a is required for dendritic positioning of late-born motoneurons but not early-born motoneurons. These findings indicate that communication within motoneurons and between glia and motoneurons, mediated by the combined action of different Plexin/Semaphorin signaling systems, are required for the formation of a functional myotopic map.

