Harinath, G. | Search bioRxiv

bioRxiv2019

Automated Lifespan Determination Across Caenorhabditis Strains and Species Reveals Assay-Specific Effects of Chemical Interventions

The goal of the Caenorhabditis Intervention Testing Program is to identify robust and reproducible pro-longevity interventions that are efficacious across genetically diverse cohorts in the Caenorhabditis genus. The project design features multiple experimental replicates collected by three different laboratories. Our initial effort employed fully manual survival assays. With an interest in increasing throughput, we explored automation with flatbed scanner-based Automated Lifespan Machines (ALMs). We used ALMs to measure survivorship of 22 Caenorhabditis strains spanning three species. Additionally, we tested five chemicals that we previously found extended lifespan in manual assays. Overall, we found similar sources of variation among trials for the ALM and our previous manual assays, verifying reproducibility of outcome. Survival assessment was generally consistent between the manual and the ALM assays, although we did observe radically contrasting results for certain compound interventions. We found that particular lifespan outcome differences could be attributed to protocol elements such as enhanced light exposure of specific compounds in the ALM, underscoring that differences in technical details can influence outcomes and therefore interpretation. Overall, we demonstrate that the ALMs effectively reproduce a large, conventionally scored dataset from a diverse test set, independently validating ALMs as a robust and reproducible approach towards aging-intervention screening.

physiology↗

bioRxiv2019

Swim exercise in C. elegans extends neuromuscular and intestinal healthspan, enhances learning ability, and protects against neurodegeneration

Exercise can protect against cardiovascular disease, neurodegenerative disease, diabetes, cancer, and age-associated declines in muscle, immune, and cognitive function. In fact, regular physical exercise is the most powerful intervention known to enhance robustness of health and aging. Still, the molecular and cellular mechanisms that mediate system-wide exercise benefits remain poorly understood, especially as applies to \"off target\" tissues that do not participate directly in training activity. Elaborating molecular mechanisms of whole-animal exercise benefits is therefore of considerable importance to human health. The development of exercise protocols for short-lived genetic models holds great potential for deciphering fundamental mechanisms of exercise trans-tissue signaling during the entire aging process. Here, we report on the optimization of a long-term swim exercise protocol for C. elegans and we demonstrate its benefits to diverse aging tissues, even if exercise occurs only during a restricted phase during early adulthood. We found that multiple daily swim sessions are essential for exercise adaptation in C. elegans, leading to body wall muscle improvements in structural gene expression, locomotory performance, and mitochondrial morphology. Swim exercise training enhances whole-animal health parameters such as mitochondrial respiration and mid-life survival and increases the functional healthspan of pharynx and intestine. Importantly, we show that swim exercise also enhances nervous system health: exercise increases learning ability of adult animals and protects against neurodegeneration in C. elegans models of tauopathy, Alzheimers disease, and Huntingtons disease. An important point is that swim training only during C. elegans early adulthood induces long-lasting systemic benefits that in several cases are still detectable well into mid-life. Overall, our data reveal the broad impact of swim exercise in promoting extended healthspan of multiple C. elegans tissues, underscore the potency of early exercise experience to influence long-term health (even after cessation of exercise), and establish the foundation for exploiting the powerful advantages of this genetic model to dissect the exercise-dependent molecular circuitry that confers long-lasting system-wide health benefits to aging or diseased adults.

neuroscience↗