Spaceflight affects neuronal morphology and alters transcellular degradation of neuronal debris in adult Caenorhabditis elegans

Ricardo Laranjeiro,Girish Harinath,Amelia K Pollard,Christopher J Gaffney,Colleen S Deane,Siva A Vanapalli,Timothy Etheridge,Nathaniel J Szewczyk,Monica Driscoll

doi:10.1016/j.isci.2021.102105

Abstract

SummaryExtended space travel is a goal of government space agencies and private companies. However, spaceflight poses risks to human health, and the effects on the nervous system have to be better characterized. Here, we exploited the unique experimental advantages of the nematode Caenorhabditis elegans to explore how spaceflight affects adult neurons in vivo. We found that animals that lived 5 days of adulthood on the International Space Station exhibited hyperbranching in PVD and touch receptor neurons. We also found that, in the presence of a neuronal proteotoxic stress, spaceflight promotes a remarkable accumulation of neuronal-derived waste in the surrounding tissues, suggesting an impaired transcellular degradation of debris released from neurons. Our data reveal that spaceflight can significantly affect adult neuronal morphology and clearance of neuronal trash, highlighting the need to carefully assess the risks of long-duration spaceflight on the nervous system and to develop adequate countermeasures for safe space exploration.

Highlights

Humankind as long been fascinated by space exploration
SpaceX CRS-16 docked to the International Space Station (ISS) on December 8, 2018, and the C. elegans samples, which were kept in cold stowage (8–13C) once introduced into their flight bags, were transferred to 20C for five days, beginning on December 9, 2018
We found that the absolute numbers of green fluorescent protein (GFP) puncta in touch neurons did not differ between middle-aged nematodes on Earth and the ones that spent the corresponding five days on the ISS (Figure S1A)

Summary

Introduction

Humankind as long been fascinated by space exploration. The International Space Station (ISS), a multinational collaborative station that orbits Earth, has been continuously occupied with crew since November 2000. Into the future, both governmental space agencies and private companies plan to send crewed missions to Mars and beyond. Much less is known about the effects of spaceflight on neuronal morphology and function, especially in vivo and at the single-neuron level. Given the impracticality of conducting such studies in humans, the use of animal models in which detailed high-resolution neuronal analyses can be performed is invaluable for assessing conserved neuronal responses to spaceflight and developing effective countermeasures to mitigate the consequences of long-duration missions

Methods

Results

Discussion

Conclusion