Figure 1. Accelerating the liver aging phenotypes of mice with Clock∆19. (A) Histological analysis of WT and ClockΔ19 mice (12, 24 and 36 week old). HE staining of inflammation foci in liver. Data were analyzed by Student’s t-test and displayed as the mean ± S.E.M. Asterisks indicate values significantly different from WT (n=4 for all groups). **, P<0.01; *, P<0.05. (B) Liver tissues stained for SA-β-gal activity. The results are expressed as the mean ± S.E.M. A significant increase in the number of positive areas was observed with ClockΔ19 (n=4 for all groups). **, P<0.01; *, P<0.05. (C) Hepatocytes were stained for SAHF foci in WT and ClockΔ19 mice. Note that the livers of ClockΔ19 mice show a clear aging phenotype. The results of the SAHF analysis are representative images of four experiments. **, P<0.01; *, P<0.05. (D) Immunoblots of liver tissue from WT and Clock∆19 mice at ZT0 and ZT12 for P53, P21 and P16 indicate the accelerated aging phenotypes. β-ACTIN was used as the loading control. **, P < 0.01 and *, P < 0.05 versus control. n=4 mice per group. (E) Immunoblots of ClockΔ19 in mouse liver tissue at ZT0 and ZT12. Note that there was no change in the protein levels in Clock∆19 mice (n=4). **, P<0.01; *, P<0.05.