Fig. 1.

Approach for inferring SnC dynamics throughout adulthood. a Many processes, including DNA damage and developmental and paracrine signals, lead to SnC production. SnCs are cleared by immune mechanisms, and secrete factors that lead to morbidity and mortality. b–d We scanned a wide class of models for SnC dynamics, and compared them to longitudinal SnC data and direct SnC perturbation experiments to establish a minimal model for SnC stochastic dynamics and determine its rate constants. In the minimal model, η is the increase in SnC production rate with age, β is the removal rate, κ is the half-way saturation point for removal, and ϵ is the noise amplitude.