Reporter alleles that inform on differences in Cre recombinase expression.

Alleles that express reporters after Cre recombination allow for fate-mapping studies when used in combination with appropriate cre alleles. In this study, we describe two fluorescent reporter alleles that differentially mark populations of cells as a function of their level of expression of Cre recombinase. Mice carrying these alleles were generated and used to demonstrate the usefulness of the reporter alleles for informing on prior Cre recombinase expression in lymphocytes. The alleles expand the range of genetic tools available for understanding how differences in gene expression result in divergent developmental fates during the development and differentiation of lymphocytes and other cells.