Figure 4. Exclusion of CeE/DA from bodywall muscle cells. The absence of detectable CeE/DA in bodywall muscle cells and their precursors is illustrated in this lateral view of a 1.5-fold embryo. (A) Reproduction of nuclear-position diagrams for the left lateral ectoderm (top) and medial (bottom) aspects of a 1.5-fold embryo (Sulston et al., 1983). Neurons have been coloured orange. (B) Lateral view of a 1.5-fold embryo stained with CeE/DA antibody showing positive, mostly neuronal nuclei in the head, ventral nerve cord and tail. Arrowheads mark the position of posterior, dorsal bodywall muscle quadrants that do not stain with the CeE/DA antibody. (C) Reproduction of the left, central mesoderm of a 1.5-fold embryo in which bodywall muscle-cell nuclei have been coloured blue (Sulston et al., 1983). (D) Beta-galactosidase staining of a 1.5-fold transgenic embryo harboring a hlh-1
::lacZ reporter gene, illustrating CeMyoD distribution at this stage of development. These muscle cells are completing differentiation and begin strong contractions shortly after this stage. (E) Detection of hlh-2
mRNA by in situ hybridization to a bean-stage embryo showing a strong signal in regions that will retain high levels of CeE/DA protein at the 1.5-fold stage, as shown in B. (F) Bean-stage embryonic expression pattern of a hlh-2
::lacZ reporter gene (see Materials and Methods). The expression pattern of this reporter is similar to the distribution of endogenous gene transcripts, as demonstrated by in situ hybridization in E. Scale bar, 10 um.