Expression of human Aγ-globin mRNA in transgenic mice containing the BGT26 and BGT34 constructs.

S1 nuclease analysis on fetal liver RNA of 15.5-day founder transgenic mice showing that BGT26 is expressed to low or undetectable levels and that BGT34 is expressed at significant levels in 4 of the 7 transgenic mice. These data show that β-globin gene sequences are required for reproducible single-copy transgene activation by 5′HS3 and that the β-globin promoter element is not sufficient for this activity. Relative specific activities of Hγ/Mβ probes is shown. Hγ, human Aγ-globin protected probe fragment; Mβ, mouse β major protected probe fragment; N, nontransgenic; C, 50-48, the highest expressing BGT50 single-copy transgenic mouse (discussed in text; see Figure 6); 3 × , probe excess control. Copy # = 1*, 1 intact copy plus a partial copy of the transgene.