Schizosaccharomyces pombe

Schizosaccharomyces pombe—fission yeast—provides a crucial evolutionary counterpoint to Saccharomyces cerevisiae for understanding aging. These two yeasts diverged approximately 500 million years ago, yet both respond to caloric restriction with extended lifespan and both use sirtuin proteins for longevity regulation. Conservation across such evolutionary distance suggests these mechanisms are fundamental rather than species-specific adaptations. What works in both yeasts likely works broadly.

Fission yeast divides by binary fission rather than budding—hence its name—providing a different model of cellular aging. In budding yeast, mother cells age while buds are rejuvenated; in fission yeast, the two daughter cells inherit damage asymmetrically, with one cell accumulating more damage through successive divisions. This asymmetric damage inheritance creates replicatively old and young lineages even in apparently symmetric division. Understanding how S. pombe manages damage inheritance has informed thinking about stem cell aging in animals.

S. pombe research revealed additional aging mechanisms that complement S. cerevisiae discoveries. The fission yeast stress response pathway, particularly the stress-activated MAP kinase Sty1, regulates lifespan in ways that parallel but don't duplicate budding yeast pathways. TOR (target of rapamycin) signaling, now known to regulate aging across species from yeast to humans, was characterized in both yeasts with complementary insights. Using two evolutionarily distant model systems—rather than just one—accelerates identification of truly conserved mechanisms.