Figure 1

Schematic representation of the concept of photoconversion of cells in culture and in embryos. Photoconversion in cells (A): Single cells or group of cells expressing a constitutively active KikGR can be labeled non-invasively. KikGR expressing cells fluoresce green before photoconversion. After exposure to short wavelength light (405 nm) a single or a group of cells of interest can be photoconverted. Photoconverted cells emit red fluorescence and can be tracked over time. Photoconversion in mouse embryos (B): Any KikGR-positive cell or group of cells of interest in a mouse embryo can be photoconverted using short wavelength light (405 nm). Photoconverted red fluorescent cells can be imaged in live static cultured embryos, so that 3D over time (4D) data sets can be acquired. Using live imaging and roller culture, a region of interest (ROI) in multiple embryos (for example all embryos in one litter) can be photoconverted in the same experiment and imaged. This is advantageous for comparing cell behavior in wild type and mutant mice before any visible onset of a phenotype.