Fig. 5: Hemoglobin enhances digging behavior in lactating mothers.

a Schematic illustration of the timeline of the cotton exposure assay. In the trials of lactating mothers, their pups were removed one hour before the cotton exposure. b–d Quantification of the digging time duration (sec) of wild type C57BL/6 lactating mothers (b), Vmn2r88-mutant lactating mothers (c), males, and virgin females (d) with pre-exposure to cotton balls transfused with hemoglobin (Hb), and fresh blood. Wild type C57BL/6 mothers; n = 15 for control, n = 6 for ESP1, n = 11 for Hb, and n = 8 for fresh blood, Vmn2r88-mutant lactating mothers; n = 5–9, virgin females; n = 9, males; n = 8. Error bars, S.E.M. (b) control vs. fresh blood; p = 0.028, control vs. Hb; p = 0.049, ESP1 vs. fresh blood; p = 0.048, and ESP1 vs. Hb; p = 0.044, and (c) +/+ (control) vs. +/+ (Hb); p = 0.017 and + /+ (Hb) vs. -/- (Hb); p = 0.041 by the two-sided Steel-Dwass test in panel (b) and (c). e, f Quantification of the total freezing duration (e) and digging time duration (f) of lactating mothers stimulated with the indicated concentration (from 100-fold to 50000-fold dilution with mineral oil) of a 2MT transfused cotton swab. n = 3 for 1000-fold and 50000-fold, n = 5 for 100-fold, n = 8 for 5000-fold and 10000-fold. Error bars, S.E.M. (e) 100-fold vs. 10000-fold; p = 0.007, 100-fold vs. 5000-fold; p = 0.007, 1000-fold vs. 10000-fold; p = 0.015, and 1000-fold vs. 5000-fold; p = 0.015, and (f) p = 0.043 by the two-sided Steel-Dwass test.