Expression of human β-globin mRNA in transgenic mice containing the BGT9 construct.

S1 nuclease analysis on fetal liver RNA of 15.5-day founder BGT9 transgenic mice showing that BGT9 is expressed in all 17 animals, including 3 single-copy mice. These data show that the 850-bp 5′HS3 element can express reproducible levels of β-globin transcripts. Relative specific activity of Hβ/Mβ probes is 1:1. Hβ, human β-globin protected probe fragment; Mβ, mouse β major protected probe fragment; N, nontransgenic; μD, 1 copy μD14 microlocus line (discussed in text).