Investigation of oxidative-stress-induced axon beading using photo-oxidation.

Oxidative stress caused by excessive reactive oxygen species adversely affects cellular function. Here, we investigate axonal beading induced by the photo-oxidation of a membrane-based fluorescent dye. Our experiments show that, apart from using oxygen scavengers, chelation of free calcium, or stabilization of microtubules or actin filaments by pharmacological agents can mitigate oxidative-stress-induced beading. Furthermore, we take advantage of this light-induced oxidative stress to explore axonal responses to spatially confined perturbations. We demonstrate that low excitation causes localized, long-lasting axon beading, whereas high excitation leads to widespread degeneration and beading. Besides the results presented here, this light-based technique is a convenient tool for investigating local oxidative stress in tissues, such as brain slices or organoids.