Fig. 1. Difference gel electrophoresis (DIGE) experimental scheme. Collections of ventralized embryos at different developmental stages were compared with lateralized embryos. (A) The general scheme for the DIGE experiments was to prepare whole embryo extracts from ventralized or lateralized embryos. The proteins within each extract were covalently labeled with either propyl-Cy3 or methyl-Cy5. The labeled protein extracts were then combined and co-electrophoresed on a 2DE gel. After electrophoresis, the gel was fixed in methanol and acetic acid and then imaged in the fluorescent gel imaging device at the Cy3 and Cy5 excitation wavelengths. Common protein spots have equal amounts of red-colored Cy3 and blue-colored Cy5, which is shown here as purple. Proteins that are unique to the Cy3-labeled sample are shown as red spots; unique Cy5-labeled proteins are shown as blue spots. (B) Ventralized and lateralized embryos were compared at three developmental stages: pre-cellularization (V^PC and L^PC), early gastrulation (V^EG and L^EG) and late gastrulation (V^LG and L^LG). Shown here are three frames from time-lapse recordings of a ventralized and of a lateralized embryo at the indicated stage. Anterior is to the left. The double-headed arrows indicate the various comparisons that were made. The cephalic furrow is indicated by arrowheads in the L^EG and L^LG images, the cephalic furrow does not form in ventralized embryos.