Abstract
Caenorhabditis elegans is a powerful animal model in aging research. Standard longevity assays on agar plates involve the tedious task of picking and transferring animals to prevent younger progeny from contaminating age-synchronized adult populations. Large-scale studies employ progeny-blocking drugs or sterile mutants to avoid progeny contamination, but such manipulations change adult physiology and alter the influence of reproduction on normal aging. Moreover, for some agar growth-based technology platforms, such as automated lifespan machines, reagents such as food or drugs cannot be readily added/removed after initiation of the study. Current microfluidic approaches are well-suited to address these limitations, but in their liquid-based environments animals swim rather than crawl, introducing swim-induced stress in the lifespan analysis. Here we report a simple microfluidic device that we call NemaLife that features: 1) an optimized micropillar arena in which animals can crawl, 2) sieve channels that separate progeny and prevent the loss of adults from the arena during culture maintenance, and 3) ports which allow rapid accessibility to feed the adult-only population and introduce reagents as needed. Culture maintenance and liquid manipulation are performed with simple hand-held syringes to facilitate integration of our technology into general laboratory protocols. Additionally, device geometry and feeding protocols were designed to emulate the body gait, locomotion, and lifespan of animals reared on agar. We validated our approach with longevity analyses of classical aging mutants (daf-2, age-1, eat-2, and daf-16) and animals subjected to RNAi knockdown of age-related genes (age-1 and daf-16). We also showed that healthspan measures such as pharyngeal pumping and tap-induced stimulated reversals can be scored across the lifespan. Overall, the capacity to generate reliable lifespan and physiological data from the NemaLife chip underscores the potential of this device to accelerate healthspan and lifespan investigations in C. elegans.
Footnotes
Electronic Supplementary Information (ESI) available: Movies demonstrating progeny washing. Worm development and arena optimization information. Protocol for lifespan assay in a microfluidic device.
