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Fig. 3 Regulation of vega1 expression and analysis of vega1 function. Whole-mount in situ hybridization for vega1 (A-E), ntl (F), gsc (G-I), boz/dha (J-L), chordin (M-O), and bmp2b (P-R); animal views (A-E, G-R), dorsal view (F), dome stage (A-E, G-I, M-O), 30% epiboly stage (P-R), shield stage (J--L), bud stage (F). (A-C) boz/dha mRNA (B; 25pg), gsc mRNA (C; 50pg) were injected into one to two cell stage embryos; (A) uninjected control. (D-F) RNA injections; CA-BMPRI mRNA (E and F; 200 pg) was injected into one to two cell stage embryos; (D) uninjected control. (E) Vega1 expression was unchanged. (F) Expression of ntl in the chordamesoderm region was suppressed (arrows), but not affected in the tailbud domain (arrowhead). (G-R) vega1 mRNA (H; 250 pg; and K, N, and Q, 100 pg) and VP16-vega1 mRNA (I, L, O, and R, 50 pg) were injected into one to two cell and two to eight cell stage embryos, respectively. (G, J, M, and P) Uninjected controls. (S-V) Phenotypic effects; lateral views, prim-6 (25 hpf) stage. Embryos were injected with vega1 mRNA (T and U; 100pg) or VP16-vega1 mRNA (V; 50pg) at the one to two cell stage. (S) Uninjected control. (W and X) Embryos from a dintt250/+X dintt250/+ cross were injected with VP16-vega1 mRNA (X; 100pg) at one to two cell stage. VP16-vega1 could not restore the ventral tail phenotype (arrowhead), whereas wild-type embryos injected with VP16-vega1 were dorsalized (V). (W) Uninjected dintt250/tt250 mutant. (Y and Z) Whole-mount in situ hybridization for pax2.1 plus ntl; 5-somite stage, dorsal view. Asterisk and arrowhead show pax2.1 and ntl staining domain, respectively. (Z) Embryos from a swirltc300/+X swirltc300/+ cross were injected with vega1 mRNA (150pg) at one to two cell stage. (Y) Uninjected swirltc300/tc300 mutant.