Generation of adult mice expressing human embryonic ζ- and -globins. (A) Construction of the hζ transgene. The full human ζ-globin transcribed region (black) was linked to the human -globin gene promoter and 5′ untranslated region (light).18 This chimeric hζ transgene was subsequently linked to a μβLCR cassette containing core elements of DNase I hypersensitive sites 1-4.21 Exons are indicated as filled boxes, and translation initiation and termination codons by tick marks. (B) Construction of the h transgene. The full-length -globin transcribed region (black) is bracketed by the β-globin promoter and 3′ flanking region (light), including the 3′ β-globin enhancer element (E). Exons and translation initiation and termination sites are indicated as in (A). (C) Expression of embryonic globins in definitive erythrocytes from mice carrying the hζ and h transgenes. Clarified erythrocyte lysates from a wild type control (−), and hζ and h adult transgenic mice were resolved by Triton-acid-urea gel electrophoresis and visualized by Coomassie blue staining.27 28 Globin bands are identified to the right. The third lane (h) was overloaded to demonstrate the h-globin product.