The use of model organisms in longevity studies has provided countless insights into the biology of aging. However, in many model organisms, such as fruit flies and roundworms, the interaction between temperature and lifespan is of greater importance than in warm-blooded animals, such as humans. In the roundworm Caenorhabditis elegans, it is established that lifespan varies inversely with temperature, but most experiments are performed for ease of completion (20° for bench-top culture or 25° for shorter experiments) rather than for optimization of temperature. Our recent work investigates the role of temperature in the lifespan of various strains of worms with disruptions in known aging-related pathways. Using 15°, 20°, and 25°C as our range of temperatures, we have found that while decreasing temperature increases lifespan in every intervention tested, the extent of the increase varies widely between strains. Thus, some strains are short or long-lived compared to wild-type only at high temperature, while others only show lifespan effects at lower temperature. Interestingly, 20°C, the most commonly used temperature in C. elegans research, shows the most variability, possibly due to small differences in temperature inside of the incubator and/or on the bench that exposes the worms to slightly higher or lower temperatures than expected.
Our current work aims to determine common mechanisms for the variability in temperature dependent lifespan changes, focusing initially on the role of heat stress response on lifespan at high temperature and the role of vulval integrity defects on lifespan at low temperature. In completing these experiments, we hope to gain insight into when and why to utilize specific temperatures for lifespan experiments in C. elegans, and potentially whether/which of these mechanisms are likely to be conserved in other model organisms.
People: Scott Leiser, George Sutphin, Marissa Fletcher