Fig. 3

Mosaic labeling with self-maintaining Kaloop. (A) Schematic representation of plm74 (upper panel) in which a 1 frameshift at a G₂₃ microsatellite results in an ORF of H2A-G22-EGFP. The reporter was injected into one-cell stage embryos with or without gal4 mRNA to temporarily activate the reporter. Stochastic expression of nuclear EGFP was observed 1 day after injection (right image) when gal4 mRNA was co-injected, but not in the absence of gal4 mRNA (left image). EGFP expression diminished within 5 days (lower image; quantified in C). (B) Schematic representation of plm78 in which, owing to a 1 frameshift, the coding sequence of EGFP, together with the linker peptide T2A and transcription activator KalTA4, becomes in-frame with the ORF of H2A-G22. Co-injection of gal4 mRNA resulted in stochastic activation of nuclear EGFP in embryos at 1 dpf, and expression was still observed in larvae at 5 dpf. (C) Quantification of injected embryos (n=100 per condition) that express nuclear EGFP.