Cholinergic neural signals regulate circadian traffic of HSCs and leukocytes in mice. (A) AChE activity in urine samples from Gfra2^−/− and WT mice collected in the nocturnal (black) and diurnal (yellow) periods. HSPCs measured as CFU-Cs (B) and WBCs (C) in peripheral blood of Gfra2^−/− mice and control Gfra2^+/− mice harvested at the specified ZT (hours after light onset). ZT1 has been duplicated to facilitate viewing. (D) HSCs, measured by long-term competitive repopulation assay, in peripheral blood harvested at ZT13 from Gfra2^−/− mice and control Gfra2^+/− mice. The log fraction of mice that failed reconstitution is plotted against the transplanted blood volume using ELDA software.⁵⁹  Likelihood ratio test of single-hit model, P = .006, χ² test. Blood HSC concentrations are indicated (n = 5). Data are mean ± standard error of the mean; n (inside bars/symbols) and P values (multivariate analysis for >2 groups) are indicated. *P < .05, ***P < .001, 1-way ANOVA and Bonferroni comparisons (A), multiple 2-tailed test (B-C), χ² test (D).