spaCe: assessing relative biological effectiveness of simulated deep space radiation in altering neural function and survival in C. elegans

The onset of neurodegenerative diseases is clearly determined by environmental and genetic factors. Insults external to the body, such as radiations, affect human body and mind in several ways. Thus, understanding how human mind adapts to the environment is an important challenge. Moreover, in light of future human explorations of deep space, a fundamental need is understanding how the nervous system may be affected by peculiar radiations that characterize this extreme environment and what genetic background can predispose to neuron dysfunction. We use the nematode C. elegans as a simple and convenient model, allowing to assess the effects of different space-relevant radiation beams on neurological function of selected groups of neurons. We demonstrated that gamma-rays affect selectively dopaminergic neurons, causing a dose-dependent degeneration of the dendrites and alteration in functionality. Interestingly, we observed in gamma-rays irradiated animals a reduction in dopamine content which might be the cause of dopaminergic neurons dysfunction. We compared this effect with another type of photons by performing X-rays irradiation and we observed that they affect dopaminergic neurons functionality in a similar way. We also tested the effect of a different type of ionizing radiation by performing protons irradiation and we observed that also protons affect dopaminergic neurons functionality, with a slightly milder effect than photons. The project aims also to discover genetic backgrounds that might sensitize or protect neurons from ionizing radiations and the molecular basis of ionizing radiation sensitivity. Thus, we discovered that cep-1/p53 has a neuroprotective role, with cep-1 mutants being more affected by gamma-rays irradiation. These results suggest that ionizing radiations reduce dopamine levels and alter dopaminergic neurons functions in vivo and also support C. elegans as a biological dosimeter for neuronal damage induced by peculiar environmental conditions like radiations in deep space.