Similarities and differences in the gene expression profiles of MnSOD over-expressing and aging in Drosophila. (a) Diagram of sampling points for the transgenic and control flies used in the gene expression profiling studies. For the control, treated (+DOX) and untreated (-DOX) flies were sampled at the 50% survival of the untreated sample, which was also approximately the 50% survival point of the treated flies. For the transgenic line, untreated flies (-DOX) were sampled at their 50% survival and a sample was also taken for DOX treated (+DOX) flies at the same time point (same chronological age). An additional sample was taken for the treated flies (+DOX) at their 50% survival (same 'physiological age'). (b) Venn diagram depicting gene expression changes due to MnSOD over-expression and the overlap with those that occur during normal aging . Yellow highlighting indicates genes whose expression levels are altered at both time points. Green shading indicates genes identified as potential biomarkers of aging. Orange or blue text denotes genes up- or down-regulated, respectively, in a given condition or in the same direction in multiple conditions. Green or purple text denotes genes up- or down-regulated, respectively, in MnSOD over-expressing flies when the direction of change is opposite in old flies. Several representative functional categorizations are noted for the various gene sets. GPCR, GTP-binding protein-coupled receptor; Hsp, heat shock protein; TCA, tricarboxylic acid cycle.