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MASTR: a technique for mosaic mutant analysis with spatial and temporal control of recombination using conditional floxed alleles in mice.


Mosaic mutant analysis, the study of cellular defects in scattered mutant cells in a wild-type environment, is a powerful approach for identifying critical functions of genes and has been applied extensively to invertebrate model organisms. A highly versatile technique has been developed in mouse: MASTR (mosaic mutant analysis with spatial and temporal control of recombination), which utilizes the increasing number of floxed alleles and simultaneously combines conditional gene mutagenesis and cell marking for fate analysis. A targeted allele (R26(MASTR)) was engineered; the allele expresses a GFPcre fusion protein following FLP-mediated recombination, which serves the dual function of deleting floxed alleles and marking mutant cells with GFP. Within 24 hr of tamoxifen administration to R26(MASTR) mice carrying an inducible FlpoER transgene and a floxed allele, nearly all GFP-expressing cells have a mutant allele. The fate of single cells lacking FGF8 or SHH signaling in the developing hindbrain was analyzed using MASTR, and it was revealed that there is only a short time window when neural progenitors require FGFR1 for viability and that granule cell precursors differentiate rapidly when SMO is lost. MASTR is a powerful tool that provides cell-type-specific (spatial) and temporal marking of mosaic mutant cells and is broadly applicable to developmental, cancer, and adult stem cell studies.

Pubmed ID: 22884371


  • Lao Z
  • Raju GP
  • Bai CB
  • Joyner AL


Cell reports

Publication Data

August 30, 2012

Associated Grants

  • Agency: NCI NIH HHS, Id: CA128158
  • Agency: NICHD NIH HHS, Id: HD050767
  • Agency: NINDS NIH HHS, Id: K08 NS066083
  • Agency: NINDS NIH HHS, Id: K08NS66083
  • Agency: NCI NIH HHS, Id: P30 CA016087
  • Agency: NCI NIH HHS, Id: R01 CA128158
  • Agency: NICHD NIH HHS, Id: R01 HD035768
  • Agency: NICHD NIH HHS, Id: R01 HD050767
  • Agency: NIMH NIH HHS, Id: R01 MH085726

Mesh Terms

  • Alleles
  • Animals
  • Chromosome Disorders
  • DNA Mutational Analysis
  • Genetic Engineering
  • Mice
  • Mice, Transgenic
  • Mosaicism
  • Mutation
  • Recombination, Genetic