imaging of evoked calcium responses indicates the intrinsic axonal regenerative capacity of zebrafish.

Calcium is an important messenger in the neuronal system, but its specific role in axonal regeneration has not been fully investigated. To clarify it, we constructed a noninvasive calcium-imaging model of zebrafish Mauthner cells and monitored subcellular calcium dynamics during axonal regeneration. Using the calcium indicator GCamp6f, we observed that the regenerative length correlated with the peak amplitude of the evoked calcium response before axotomy, which suggested that the evoked calcium response might serve as a useful indicator of evoked neuronal activity and axonal regenerative capacity.

In vivo imaging of Mauthner axon regeneration, remyelination and synapses re-establishment after laser axotomy in zebrafish larvae.

Zebrafish is an excellent model to study central nervous system (CNS) axonal degeneration and regeneration since we can observe these processes in vivo and in real time in transparent larvae. Previous studies have shown that Mauthner cell (M-cell) axon regenerates poorly after mechanical spinal cord injury. Inconsistent with this result, however, we have found that M-cell possesses a great capacity for axon regeneration after two-photon laser ablation.