Figure 6
From: A mechanism for the sharp transition of morphogen gradient interpretation in Xenopus
Heterogeneous expression of Xbra in Xenopus animal pole blastomeres. (A) Heterogeneous expression of Xbra in Xenopus animal pole blastomeres treated with uniform concentrations of activin. Dissociated Xenopus animal cap cells were treated with various concentrations of activin as indicated. The cells were fixed and stained by indirect immunofluorescence using an anti-Xbra antibody. Yellow arrowheads indicate the nuclei that are Xbra-negative among positive nuclei (0.5 U) or vice versa (1 U). Cells were counterstained with Hoechst33342 (DNA). Scale bar = 50 μm. (B) Plot of Xbra versus DNA fluorescences. The fluorescence was quantified as described in Methods.