Fig. 1.

Generation and characterization of Tg(Pw1^IRESnLacZ) reporter mice. (A) The 508P6 BAC (180 kb) contains all nine exons (gray boxes) of Pw1. Zim1 is located <40 kb from Pw1 and transcribed in the opposite direction (arrows). An IRESnLacZ-pA (blue) and a floxed (red triangles) kanamycin (Kana, pink) cassette were introduced into the 5′ portion of Pw1 exon 9. The kanamycin cassette was excised before BAC injection. (B and C) Whole-mount X-galactosidase (X-Gal) staining of E11 Tg(Pw1^IRESnLacZ) (B) and whole-mount in situ hybridization of E11 wild-type embryos (C). The same expression pattern is seen in the hindbrain (hb), brachial arches (ba), heart (h), apical epidermal region of the fore- (fl), and hindlimb (hl) buds, and somites (so). (D and E) sagittal sections of Tg(Pw1^IRESnLacZ) (D) and wild-type (E) embryos at E11. Reporter activity (D) and endogenous PW1 protein (E) are detected in the floor and roof plate of the neural tube (arrows) and the hypaxial domain of the somites (arrowhead). (F and G) Cross sections of Tibialis Anterior muscle from 7 wk-old reporter mice. Reporter activity is detected in satellite cells (yellow arrowheads), identified by Pax7 expression, and PICs (white arrowheads) (F). PW1 and reporter activity colocalize (G, white arrowheads). [Scale bars, 100 μm (D, E), 50 μm (F, G).]