Oleic acid protects Caenorhabditis mothers from mating-induced death

Reproduction comes at a cost, including death. Previous studies of the interconnections between reproduction, lifespan, and fat metabolism in C. elegans were predominantly performed in low-reproduction conditions. To understand how increased reproduction affects lifespan and fat metabolism, we examined mated worms; we find that a Δ9 desaturase, FAT-7, is significantly up-regulated. Dietary supplementation of oleic acid (OA), the immediate downstream product of FAT-7 activity, restores fat storage and completely rescues mating-induced death, while other fatty acids cannot. OA-mediated lifespan restoration is also observed in C. elegans mutants suffering increased death from short-term mating, and in mated C. remanei females, indicating a conserved role of oleic acid in post-mating lifespan regulation. Because OA supplementation does not further increase the reproductive span or the brood size of mated C. elegans mothers, our results suggest that altering specific fat metabolism uncouples reproduction and somatic lifespan regulation, providing potent targets to ameliorate the cost of reproduction.