Figure 1.

Breeding scheme. Homozygous C57BL/6J lacZ-plasmid transgenic mice (Prop1⁺/Prop1⁺, lacZ^A/A,B/B), carrying two integration sites, one on chromosome 3 (A) and one on chromosome 4 (B) were crossed to heterozygous Ames dwarf (Prop1^df/Prop1⁺, lacZ^{−/−,−/−}) mice. The heterozygous Ames dwarf F1 (Prop1^df/Prop1⁺, lacZ^A/−,B/−) were backcrossed with homozygous C57BL/6J lacZ-plasmid transgenic mice (Prop1⁺/Prop1⁺, lacZ^A/A,B/B) up to F5 generation. The F5 heterozygous Ames were backcrossed to the original Ames background and the offspring were used in the experiment. Both homozygous dwarf (DF; Prop1^df/Prop1^df, lacZ^A/−,B/−) and wild-type (WT; Prop1⁺/Prop1⁺, lacZ^A/−,B/−) animals were ad lib (AL) fed or calorie-restricted (CR).