One of the major concerns with lengthy space missions is the loss of muscle mass and strength in astronauts. Due to the analogous muscle structure and conservation of genes between humans and Caenorhabditis elegans, we have used C. elegans as a model organism for studying the changes in muscle biology experienced by humans in space. Previous experimental studies conducted on the ISS showed that genes that encode muscle attachment complexes have decreased expression under microgravity. To address whether these genes directly affect the muscular strength of C. elegans, we developed a microfluidic device called NemaFlex that enables the measurement of nematode strength. NemaFlex contains deformable hanging pillars that are deflected by the worm as it navigates within the device. From imaging the pillar deflections, nematode strength can be extracted. Using NemaFlex we showed that mutation of two genes encoding muscle attachment complex proteins, unc-112 and unc-52) were indeed weaker than wild-type on Earth (Etheridge et al 2014). We will now use NemaFlex onboard at the ISS to detect microgravity-induced changes in muscle strength occur as predicted from past flight and ground based experiments. We will conduct these experiments over 7 generations and also conduct gene expression analysis. To validate the technology and experimental workflow for spaceflight, we have performed various ground experiments. First, we have configured the NemaFlex device to sort and house individuals of similar size in small chambers reducing crew time for imaging. Second, we have grown wild-type C. elegans and dys-1 worms in a spaceflight-proven axenic media called C. elegans maintenance media (CeMM), both in culture dishes and spaceflight-proven culture bags made of fluorinated ethylene propylene (FEP). Third, we optimized a protocol, that avoids bubbles and removes progeny, for astronauts use to load animals into the NemaFlex device. Launch of our experiment is anticipated later this year.

Affiliations:
- MRC, Arthritis Research UK Centre for Musculoskeletal Aging Research, University of Nottingham, UK
- Department of Electrical Engineering, Texas Tech University, Lubbock, TX
- Department of Chemical Engineering, Texas Tech University, Lubbock, TX