Time-course of a representative y/w embryo with the tFT-Bcd reporter from the division cycle 10 to the early gastrulation. A SPIM images of the embryo early development. Embryo "shells" are displayed. Left: Green fluorescence, center: Red fluorescence, right: Intensity-weighted ratiometric image of the mCherry/sfGFP ratio, reporting average protein age. The scale corresponds to 50 μm. B Quantification of the same embryo as is A. Each line represents the fluorescence profile along the anterior-posterior axis of the embryo for a time frame (separated by 6 min). In the lower panel, where the mCherry/sfGFP ratio is shown, the posterior half of the embryo is not shown because the signal drops to the background levels (due to softer imaging conditions for the long term time-course). C The same data is shown as a function of time for different embryo segments. 