Background: Mitochondrial health is difficult to assess in vivo. Results: We have generated a reporter gene, MitoTimer, which targets mitochondria, and fluoresces green and shifts to red when oxidized, for assessment of mitochondrial content, structure, stress, and damage under physiological and pathological conditions. Conclusion: MitoTimer is useful for assessment of mitochondrial health in vivo. Significance: MitoTimer could advance mitochondrial research in multiple disciplines.

Limiting the debilitating consequences of ageing is a major medical challenge of our time. Robust pharmacological interventions that promote healthy ageing across diverse genetic backgrounds may engage conserved longevity pathways. Here we report results from the Caenorhabditis Intervention Testing Program in assessing longevity variation across 22 Caenorhabditis strains spanning 3 species, using multiple replicates collected across three independent laboratories. Reproducibility between test sites is high, whereas individual trial reproducibility is relatively low. Of ten pro-longevity chemicals tested, six significantly extend lifespan in at least one strain. Three reported dietary restriction mimetics are mainly effective across C. elegans strains, indicating species and strain-specific responses. In contrast, the amyloid dye ThioflavinT is both potent and robust across the strains. Our results highlight promising pharmacological leads and demonstrate the importance of assessing lifespans of discrete cohorts across repeat studies to capture biological variation in the search for reproducible ageing interventions.

Hyperactivation of the Caenorhabditis elegans MEC-4 Na(+) channel of the DEG/ENaC superfamily (MEC-4(d)) induces neuronal necrosis through an increase in intracellular Ca(2+) and calpain activation. How exacerbated Na(+) channel activity elicits a toxic rise in cytoplasmic Ca(2+), however, has remained unclear. We tested the hypothesis that MEC-4(d)-induced membrane depolarization activates voltage-gated Ca(2+) channels (VGCCs) to initiate a toxic Ca(2+) influx, and ruled out a critical requirement for VGCCs. Instead, we found that MEC-4(d) itself conducts Ca(2+) both when heterologously expressed in Xenopus oocytes and in vivo in C. elegans touch neurons. Data generated using the Ca(2+) sensor cameleon suggest that an induced release of endoplasmic reticulum (ER) Ca(2+) is crucial for progression through necrosis. We propose a refined molecular model of necrosis initiation in which Ca(2+) influx through the MEC-4(d) channel activates Ca(2+)-induced Ca(2+) release from the ER to promote neuronal death, a mechanism that may apply to neurotoxicity associated with activation of the ASIC1a channel in mammalian ischemia.

Regular physical exercise is the most efficient and accessible intervention known to promote healthy aging in humans. The molecular and cellular mechanisms that mediate system-wide exercise benefits, however, remain poorly understood, especially as applies to tissues that do not participate directly in training activity. The establishment of exercise protocols for short-lived genetic models will be critical for deciphering fundamental mechanisms of transtissue exercise benefits to healthy aging. Here we document optimization of a long-term swim exercise protocol for Caenorhabditis elegans and we demonstrate its benefits to diverse aging tissues, even if exercise occurs only during a restricted phase of adulthood. We found that multiple daily swim sessions are essential for exercise adaptation, 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 midlife survival, increases functional healthspan of the pharynx and intestine, and enhances nervous system health by increasing learning ability and protecting against neurodegeneration in models of tauopathy, Alzheimer’s disease, and Huntington’s disease. Remarkably, swim training only during early adulthood induces long-lasting systemic benefits that in several cases are still detectable well into midlife. 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, and establish the foundation for exploiting the powerful advantages of this genetic model for the dissection of the exercise-dependent molecular circuitry that confers system-wide health benefits to aging adults.