(604d) Microfluidic Devices for Phenotyping Caenorhabditis Elegans in Liquid Culture Vessels on the International Space Station

Significant pathophysiological changes occur in astronauts during spaceflight. For example, even a week-long stay at the International Space Station (ISS) can lead to 20% muscle mass loss, which poses a serious concern for interplanetary human missions. Model organisms present a useful means to understand how spaceflight induced environmental stresses impact organismal physiology. The nematode, C. elegans has proven to be a compelling model for space flight studies, due to conserved human-relevant biology, large sample size and cost-effectiveness due to low upload mass and small foot-print. Yet, space-flight studies in C. elegans have mostly focused on obtaining molecular data (e.g. transcriptomic data), and organismal-level phenotypic data is limited. The main challenge in obtaining organismal phenotypic data is lack of tools that can culture C. elegans over several days, while minimizing crew time, maximizing safety and facile integration with imaging hardware. For example, standard culture on agar plates and liquid cultures is not optimal for image-based phenotyping due to the difficulty of maintaining animals in a single focal plane. Here, we present a novel culture environment combining the advantages of liquid and microfluidic cultures, to ease on-orbit culturing and enable high-resolution phenotyping. The design of the microfluidic devices allows animals to crawl while providing access to nutrients and removal of waste. The shallow chamber height keeps animals in a singular focal plane facilitating imaging. We perform bench-marking experiments and find that the animals can be cultured successfully across several days with growth rates that are comparable to standard cultures. We characterize the performance of these microfluidic devices in terms of media transport, and depletion. Additionally, different bacterial diets are evaluated to understand how culture conditions can influence C. elegans survival, locomotion, and growth in the designed microfluidic devices. These validation studies inform on the benefits and constraints offered by microfluidic devices for phenotypic studies with C. elegans on the International Space Station.