Genetic Mosaic Analysis in Model Organisms

The definition of genetic mosaicism is the presence of cells with various genotypes within the same animal, which could be caused by somatic transposition, mitotic recombination, or genomic aberrations, including the formation and irregular segregation of ring chromosomes. Because naturally occurring mutant cells in genetic mosaic animals cannot be effectively studied due to the difficulty in tracking them down, a genetically engineered mosaic mouse model termed mosaic analysis with double markers (MADM) was established to enable one to perform phenotypic analysis of mutant cells in vivo by unequivocally labeling them with green fluorescent protein (GFP) and red fluorescent protein (RFP). With its single-cell resolution, MADM is highly suitable for studying developmental biology, neuroscience, and regenerative biology problems caused by stochastically distributed mutant cells in mice.