Male (8-month-old) Clk^Δ19/Δ19 and Clk^wt/wt mice fed a Western diet for 2 months were injected i.p. 3 times with 30 mg/kg CoCl₂ on alternate days, and continued on the same diet ad libitum for 2 months. Mice were used for tissue analysis (n = 6 per group) or to study hepatic uptake of [³H]OA (n = 5–6 per group). (A–E) Livers were used to measure mRNA levels. Mean ± SD; *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001, multiple t tests. (F) Frozen liver sections were used for Oil Red O, H&E, and anti-macrophage (anti-CD68) staining. Pictures are representative of 3 experiments. (G and H) Livers were used to measure triglyceride (G) and TBARS (H). Mean ± SD; ****P < 0.0001, Welch’s 2-tailed t test. (I) Plasma ALT and β-HB levels in Clk^Δ19/Δ19 mice injected with CoCl₂. Mean ± SD; **P < 0.01, ****P < 0.0001, Welch’s 2-tailed t test. (J) Clk^Δ19/Δ19 and Clk^wt/wt mice were injected with CoCl₂. Two weeks later, mice were injected i.p. with [³H]OA. After 2 hours, livers were collected, and radioactivity was measured. Mean ± SD; ****P < 0.0001, Welch’s 2-tailed t test. (K) Liver slices from 10-month-old Clk^Δ19/Δ19 and Clk^wt/wt mice treated with CoCl₂ were incubated with [³H]OA (1 μCi/mL) for 1 hour, washed, and used to measure protein and radioactivity. Mean ± SD; *P < 0.05, ****P < 0.0001, 2-way ANOVA, Šidák’s multiple-comparisons test. (L) Liver slices from 10-month-old Clk^Δ19/Δ19 and Clk^wt/wt mice treated with or without CoCl₂ were incubated with [¹⁴C]palmitic acid (PA) (1 μCi/mL) for 2 hours. ¹⁴CO₂ adsorbed to paper and acid-precipitated intermediates were counted. Mean ± SD; *P < 0.05, **P < 0.01, 2-way ANOVA, Šidák’s multiple-comparisons test. (M) Primary hepatocytes from Clk^Δ19/Δ19 and Clk^wt/wt mice were treated with CoCl₂ (250 μM) for 12 hours, incubated with 0.5 μCi/mL of [³H]OA for 1 hour, washed, and counted. Mean ± SD; *P < 0.05, **P < 0.01, ****P < 0.0001, 2-way ANOVA, Šidák’s multiple-comparisons test. (N) Primary hepatocytes from Clk^Δ19/Δ19 and Clk^wt/wt mice were treated with DMOG (500 μM) for 8 hours, incubated for 1 hour with 0.5 μCi/mL [³H]OA, and washed, and radioactivity was determined to measure uptake or hepatocytes were incubated with [¹⁴C]PA for 1 hour to study fatty acid oxidation. Mean ± SD; *P < 0.05, ***P < 0.001, 2-way ANOVA, Šidák’s multiple-comparisons test. (O) WT hepatocytes were transduced in triplicate with adenoviruses expressing shCLOCK, shHIF1α, shCD36, or shCTRL. After 60 hours, cells were treated with CoCl₂ for 12 hours and fatty acid uptake was measured. Mean ± SD; ***P < 0.001, 2-way ANOVA, Šidák’s multiple-comparisons test.