Single-cell Proteomics of Developing Cells in Live Vertebrate Embryos by Microprobe High-Resolution Mass Spectrometry

In this work, we developed a microprobe capillary electrophoresis high-resolution mass spectrometry approach to identify proteins in single identified cells in live embryos of the South African clawed frog (Xenopus laevis) and also zebrafish. We used a pulled borosilicate capillary to aspirate a calibrated portion of the cell of interest. Proteins in the collected aspirate were detected and quantified via a bottom-up proteomic workflow that was downscaled to the single cells. The microprobe mass spectrometry platform is scalable to smaller cells in live, morphologically complex, developing embryos. As an example, we used this approach to analyze proteomic changes in cells that form a clone in the early developing Xenopus laevis embryo.