Caenorhabditis Intervention Testing Program: all-trans retinoic acid lifespan extension in Caenorhabditis elegans requires 5-Fluoro-2'-deoxyuridine (FUdR).

The Caenorhabditis Intervention Testing Program recently characterized the longevity-promoting effects of all-trans-retinoic acid (atRA) in C. elegans . While we observed that atRA extended lifespan across multiple genetic backgrounds, environmental factors may influence its efficacy. One such factor is 5-Fluoro-2'-deoxyuridine (FUdR), used to prevent progeny contamination in lifespan assays. Here, we show that FUdR enhances atRA's lifespan effects, but that this potentiation is not simply due to progeny elimination, as sterilization through auxin-mediated disruption of spermatogenesis does not potentiate atRA in lifespan extension. We conclude that atRA longevity is dependent on additional effects of FUdR that remain uncharacterized.