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Calcium wave fronts that cross gap junctions may signal neuronal death during development
L R Wolszon1, V Rehder, S B Kater
1Department of Biological Sciences, Columbia University, New York, New York 10027.
Summary
In leeches, embryonic neurons signal cell death via calcium waves that travel slowly through gap junctions to neighboring neurons. This calcium signaling prompts the surviving neuron to grow into the vacated space.
Area of Science:
- Neuroscience
- Developmental Biology
- Cell Biology
Background:
- Embryonic anterior pagoda (AP) neurons in leeches interact via transient axons during development.
- Ablation of an AP neuron triggers its homolog to reinitiate axon growth into the vacated territory.
- The mechanism of cell death communication between AP neurons is unknown.
Purpose of the Study:
- Investigate if gap junctions mediate cell death signals between developing leech neurons.
- Examine calcium dynamics in embryonic AP cells as a potential intercellular signal.
Main Methods:
- Studied calcium dynamics in embryonic AP cells in situ.
- Induced focal calcium rise in AP axons using a UV microbeam.
- Observed calcium wave propagation and transfer between coupled neurons.
Main Results:
- Robust calcium buffering and pumping mechanisms were present, not calcium-releasing stores.
- Induced calcium rise propagated as a slow wave (0.05-0.25 micron/sec) away from the lesion.
- Calcium waves crossed gap junctions into neighboring AP neurons but did not propagate further.
Conclusions:
- Calcium dynamics are consistent with a role in signaling cell death between coupled AP neurons.
- Calcium waves crossing gap junctions may trigger the compensatory growth response in neighboring neurons.