Effects of altering DAF-16a dosage on lifespan. (A) Expression levels of daf-16a mRNA in various daf-16(mgDf50); daf-2(e1370); daf-16a::gfp strains were compared to that of daf-2(e1370) worms. The graph is plotted on a log2 scale. Error bars represent standard deviation (S.D.) from two independent repeats. Statistical values are given in Additional file 1: Table S2. (B) Lifespan of daf-16(mgDf50) worms carrying various daf-16a::gfp transgenes as well as low-copy daf-16d/f::gfpHT. Three high-copy daf-16a transgenic worms live longer than wild type. daf-16a::gfpHT worms lived shorter than wild-type, while the lifespan of the daf-16d/f::gfpHT strain is comparable to wild type. (C) Lifespan of daf-16(mgDf50); daf-2(e1370) worms carrying various daf-16::gfp transgenes. daf-16a::gfpHT worms lived shorter than the daf-2(e1370) mutants. daf-16(mgDf50); daf-2(e1370); daf-16a::gfpGR worms had the shortest lifespan among the high-copy daf-16a transgenic strains. daf-16d/f::gfpHT transgene alone fully rescued the lifespan extension of daf-2(e1370) mutants. One lifespan experiment is shown from a total of three repeats; each with similar results. All lifespan data are shown in Additional file 1: Table S3.