Deletion or ectopic reinsertion of HS −40 influences the interactions between the remote HS and the α-globin genes. Intrachromosomal interactions involving human remote regulatory sequences and the human α-globin genes in normal, ΔHS −40, and 3′HS −40 humanized alleles. (A) Chromosomal organization of the humanized α-globin locus. (B) Chromosomal organization of the mouse α-globin locus. Red and blue numbers indicate, respectively, the points (coordinates) of the human and mouse primers analyzed by q3C. q3C assays were performed using HindIII-digested, fixed chromatin from primary Ter119⁻ (blue graph bars) and Ter119⁺ (red graph bars) cells from spleens obtained from phenylhydrazine-treated mice. The bar chart (y-axis in panels C-H) shows the enrichment of PCR product (%) normalized to the enrichment within the mouse Ercc3 gene (= 100%), and thus explains the scale difference compared with Figure 1, normalized on human Ercc3. These independent graphs represent a measure of the association between the remote regulatory sequences (x-axis) to the α-globin genes (anchor fragment) in normal-humanized locus (C), endogenous mouse locus (D), ΔHS −40 humanized locus (E), endogenous mouse locus (F), 3′HS −40 humanized locus (G), and endogenous mouse locus (H). Results obtained with endogenous mouse locus are in agreement with those observed previously.²  Data are represented as in Figure 1. To the left are images representing the proposed configurations interpreted from these data.