Expression of anteroposterior-axis-patterning proteins

Patterns of toolkit-gene expression correspond to mutant phenotypes. Drosophila embryos have been stained with antibodies to the (a) maternally derived Bicoid protein, (b) Krüppel gap protein, (c) Hairy pair-rule protein, and (d) Engrailed segment-polarity protein and visualized by immunoenzymatic (staining is brown) (a) or immunofluorescence (staining is green) (b–d) methods. Each protein is localized to nuclei in regions of the embryo that are affected by mutations in the respective genes.

[Photomicrographs courtesy of (a) Ruth Lehmann and (b–d) James Langeland.]