Researchers at the University of Washington have found a genetic pathway linking nutrient response and the aging process, they report in the Nov. 18 issue of the journal Science. The UW researchers conducted a genome-wide screen of yeast cells to find which genes, and their corresponding proteins, affect lifespan. Two of the proteins, called Tor1 and Sch9, are signaling molecules that are linked to nutrient uptake in many different organisms. Their results suggest that the same proteins, or very similar ones, may be related to both nutrient response and the aging process in humans. After finding ten genes that regulate lifespan, the researchers tested two Tor1 and Sch9 to confirm their connection to caloric restriction. They saw lifespan increases in modified yeast cells that were about the same as a cell that had just the Tor1 mutation, indicating that the mutation was doing the same thing as caloric restriction.