Fig. 6: Proposed model.

In control conditions, there is very low fmo-2 expression, leading to low levels of tryptophan metabolism/kynurenine production through FMO-2, and maintaining normal flux through one carbon metabolism and normal lifespan. When fmo-2 is induced, FMO-2 oxygenates tryptophan, leading to increased kynurenine production and decreased methylation output flux through OCM, thereby extending nematode lifespan. When fmo-2 is absent, these metabolic changes do not occur, preventing an extension in lifespan. The gray line represents decreased flux and the blue line represents increased flux.