Figure 5

In vivo longitudinal monitoring of a photoconverted subpopulation of melanoma cells indicated by the gray box in a zebrafish xenograft model following in situ photoconversion. In all images, the eye is located at the bottom-left of the field of view and was consistently used as a fiducial marker throughout the experimental time course to ensure monitoring of the same area over time. The top row shows a colored overlay of the two collected fluorescence emission bands, namely 650–690 nm in green and 760–800 nm in red. The middle row shows a scatter plot of each pixel, where green and red channel intensities are plotted against one another in order to generate a representation visually reminiscent of flow cytometry plots. The red dashed lines in the scatter plots correspond to the gating criteria to identify pixels containing either photoconverted or standard DiR. These gates are then used to recolor the images from the top row, where the images in the bottom row show photoconverted and standard DiR fluorescence in green and red, respectively.