Transferrin saturation and diferric transferrin levels are increased in hbd mice. (A) Plasma transferrin saturation was measured in 10- to 12-week-old wild-type (C57BL/6J; ) and hbd (▪) mice on either a control or an iron-deficient diet (n = 7-11; ^**P < .01 relative to wild-type mice). (B) To determine the levels of diferric transferrin in wild-type and hbd mice on a control diet, rivanol extracts derived from the equivalent of 60 nL serum were subjected to urea polyacrylamide gel electrophoresis followed by Western blotting with an antibody to transferrin (top panel). Total transferrin levels determined by analysis of the same samples by sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-PAGE) followed by Western blotting demonstrated that there was no difference between C57BL/6J mice and hbd mice (bottom panel). Total transferrin was used as a loading control for the diferric transferrin gels because an independent measure of serum transferrin levels (total iron-binding capacity) showed no differences between the strains (data not shown). Four replicates are shown for each group. (C) Densitometric analysis of the gels shown in panel B. The graph shows the relative diferric transferrin levels expressed as a proportion of the control level of diferric transferrin in C57BL/6J mice. The data represent the mean ± SEM (n = 4; ^**P < .01).