Expression pattern of the BmNPV <i>ie1</i>-EGFP transgene in silkworm embryos.

<p>(A–D) Merged images of EGFP fluorescence and epi-illumination. (A) Stage 17 embryo. EGFP expression driven by the <i>ie1</i> promoter was not evident in stage 17 embryos. Most yolk had been removed. (B) Stage 18 embryo. EGFP expression was evident in some yolk cells at this stage. (C) Stage 20 embryo (dorsal closure has not complete). EGFP expression was detected in the lateral and dorsal region. (D) Stage 21B embryo. EGFP fluorescence extended to ventral region. Most yolk had been removed. (E) Ventral view of a stage 21B embryo. Merged images of DsRed fluorescence and epi-illumination. The DsRed transformation marker was evident in the developing ventral nerve cord from this stage. (F) Stage 23 embryo (dorsal closure has completed). EGFP expression was detected throughout the whole embryo at this stage. (G, G’) Stage 26 embryo. (H, H’) Stage 29 embryo. EGFP and DsRed fluorescences were obscured by the pigmentation in the cuticle. In all panels, anterior is to the left. All panels except the panel E present a lateral view. Abbreviations: T3L, the 3rd thoracic leg; VNC, ventral nerve cord; y, yolk. Arrowhead indicates stemma. Scale bars = 500 µm.