Fig. 4

Regulatory function of the hoxb1b upstream DNA during somitogenesis. (A–F) Expression of hoxb1b mRNA from 80% epiboly to the 20-somite stage (20-s). (G–J) Expression of 5′hoxGFP mRNA in Tg embryos from the bud stage to 30 hpf. (K–N) Expression of 5′hoxGFP (K), hoxb1b (L), hoxb5b (M), and hoxb6b (N) was compared with krox20 expression in r3 and r5 by in situ hybridization. (O–S) Transient (O) and stable (P-S) expression of 5′hoxGFP was visualized by fluorescence from 4-somite stage through 28 hpf. (A–C, E–N, S) Dorsal views with anterior to the top (A–C, E–I, K–N) or to the left (J, S). (D, O–R) Lateral views with anterior to the left and dorsal to the top. The anterior expression boundaries of hoxb1b and 5′hoxGFP are shown with open arrowheads, whereas those of hoxb5b and hoxb6b are shown with black arrowheads. Transgene expression in the posterior pharyngeal arches, diencephalon, MHB, and otic vesicles is shown with black/white thin arrows, yellow thin arrows, open circles, and asterisks, respectively. Scale, 200 μm.