Figure 5. Microarray validation and determination that genes encoding antioxidants are downregulated in aging SSCs. (A) Quantitative RT-PCR validation of the differential gene expression of 15 selected transcripts observed in the microarray analysis of rapamycin-exposed SSCs (THY1+/GFRA1+ cells enriched by MACS). Nine upregulated genes, Gfra1, Ret, Lin28b, Nanos2, Foxo1, Alad, Sod1, Gsr, Erbb2, and six downregulated genes, Wnt3a, Tgfbr1, Stat4, Tnf, Gsc, Meox2, were compared to endogenous control Gapdh(assigned a relative value of “1”). (B) Quantitative RT-PCR compared THY1+/GFRA1+ cells enriched by MACS from 55-week-old wild type males to MACS-enriched cells from 3-week-old controls. When compared to endogenous control Gapdh, the fold-changes in expression of Alad, Sod1, and Gsr were all significantly diminished in the aged SSCs versus the young SSCs (1.46-, 1.72-, and 1.62-fold, respectively).Data represent mean values +/− SEM from three biological replicates. Student's t-test was performed to individually assess significance between each transcript and endogenous control Gapdh; *p<0.05, **p<0.01, ***p<0.001.