Figure 4.

Nuclear run-on transcriptional assay in A6 cells and embryos. Transcriptional activity was monitored by a nuclear run-on assay with incorporation of Br-UTP in permeabilized A6 cells (A) and in embryos (D), as detailed in MATERIALS AND METHODS. A6 cells were fixed after 10 min of labeling and double stained for incorporated Br-UTP (A), and xSAHH (B). The confocal images shown in A and B are superimposed in C. Bar, 10 μm. (D and E) A midgastrula embryo at stage 10.5 was coinjected with digitonin and ribonucleotides including Br-UTP and fixed after 60 min of labeling at stage 11. The gastrula was dissected in halves along the animal to vegetal axis, and halves were double stained as whole mounts for the Br-UTP label and for xSAHH. Confocal images of the surface show coincident nuclear staining with anti BrU (D) and with mAb 32-5B6 for xSAHH (E). Bar, 200 μm.