Live Cell Imaging to Monitor Axonal Pruning in Drosophila Motor Neurons

Area of Science:

• Neuroscience
• Developmental Biology
• Genetics

Background:

• Neuronal circuits require precise wiring, involving overproduction and subsequent pruning of neurites.
• Axon pruning is essential for refining neural connections during development and in response to environmental stimuli.
• Drosophila melanogaster serves as a model organism for studying conserved genetic and cellular mechanisms of neural development.

Purpose of the Study:

• To investigate the mechanism of axon pruning in Drosophila motor neurons.
• To establish a live-cell imaging protocol for observing motor axon bundle degeneration.
• To identify conserved genes regulating axon pruning in motor neurons.

Main Methods:

• Utilizing live-cell imaging to monitor the degeneration of long-range projecting axon bundles in Drosophila motor neurons.
• Analyzing the developmental timing of axon bundle clearance during metamorphosis.
• Comparing gene regulation of motor neuron axon pruning with that of mushroom body gamma neurons.

Main Results:

• Drosophila motor neurons prune intermediate axon bundles through degeneration, distinct from terminal neuromuscular junction (NMJ) pruning.
• The complete clearance of these axon bundles was observed approximately 22 hours after pupal formation (22 h APF).
• Genes regulating mushroom body (MB) γ neuron axon pruning are conserved in motor neurons.

Conclusions:

• Axon pruning in Drosophila motor neurons occurs via degeneration of axon bundles, offering a tractable system for study.
• Live imaging provides a powerful tool for real-time analysis of axon pruning dynamics.
• Conserved genetic pathways underscore the fundamental mechanisms of neural circuit refinement across different neuron types.