Rapid detection of β-lactamase gene expression. (A–D) One-cell-stage embryos were injected with 1 mM CCF2 (right embryo) or with 1 mM CCF2 + 10 ng/μl pXex–β-lactamase plasmid DNA (left embryo). Detection with the CCF2 filter set at the oblong stage (3.7 h at 28.5°C) (A), sphere (4 at 28.5°C) (B), 30% epiboly (4 h at 28.5°C) (C), 80% epiboly (8.5 h at 28.5°C) (D), and 10 somites stage (14 h at 28.5°C) (E). (F–H) One cell stage embryos were injected with 10 ng/μl of pXex–mmGFP plasmid and fluorescence was detected using the fluorescein filter set at 50% epiboly (5.3 h at 28.5°C) (F), 80% epiboly (8.5 h at 28.5°C) (G) and at the 10 somites stage (14 h at 28.5°C) (H).

Cell-autonomous detection of the β-lactamase marker. (A) One-cell-stage embryos were injected with CCF2 and later at the 16-cell stage one of the marginal blastomeres was injected with β-lactamase mRNA. At this stage the cytoplasm of the marginal blastomeres is not separated allowing the mRNA to diffuse and to be translated in more than 1/16 of the cells. (B, C) One-cell-stage embryos were injected with CCF2 and later at the 64-cell stage one of the blastomeres was coinjected with β-lactamase mRNA and with rhodamine dextran as a lineage marker. At 30% epiboly the yolk was removed and a flat preparation of the embryo was visualized at a high magnification using the CCF2 filter set (B) or with a filter set for rhodamine detection (C).