#$%^&*AU2013206647A120130718.pdf#####Abstract The invention provides methods and compositions for modulating the life span of eukaryotic and prokaryotic cells and for protecting cells against certain stresses, e.g., 5 heatshock. One method comprises modulating the flux of the NAD+ salvage pathway in the cell, e.g., by modulating the level or activity of one or more proteins selected from the group consisting of NPT1, PNCl, NMAl and NMA2.