Cover Story

The analysis of gene function in biological processes by usinggenetic mosaic animals has a long tradition, especially in geneticallytractable organisms. The recently developed MADM (Mosaic Analysiswith Double Markers) technology offers a unique contemporary approachto generate mosaic mice in order to visualize and concomitantly manipulategenetically defined cells at clonal level and single cell resolution. MADMemploys Crerecombinase/loxP-dependent interchromosomal recombination toreconstitute two split marker genes (green GFP and red tdTomato), and canlabelsparse clones of homozygous mutant cells in one color and wild-type cells inthe other color. MADM applications are limitless and MADM can be applieduniversally in the mouse with the sole restriction being the specificity of thepromoter controlling Crerecombinase expression.Most popular MADMapplications include lineage tracing, single cell labeling, and conditionalknockouts in small populations of cells.

Image caption: Illustration of MADM labeling in the hippocampus in a three week oldmouse brain. DAPI staining (blue) outlinesthe general organization of the hippocampus.