Fig. 1. Generation and hematopoietic labeling of the ancestry mice. (A) Structure of the vav-Cre transgenic vector showing the hypersensitivity sites (HS) of the vav elements, the insulator sequences (INS) and the IRES-YFP element, which was not functional in vivo (indicated by the lowercase letters), and of the ROSA26R-YFP locus before and after Cre-mediated excision of the stop cassette. (B) Cross of vav-Cre transgenic mice with ROSA26R-YFP mice. F1 animals with the vav-Cre transgene segregated into two phenotypes, which were distinguished by the expression of YFP in the skin of chimeric control mice (yellow patches) and the absence of such a labeling in vav ancestry mice. The F1 mice without the vav-Cre transgene were used as negative controls. The tubes at the bottom containing grey or yellow `cells' indicate the degree of hematopoietic labeling in the different mice. (C) FACS analysis of mononucleated cells from adult bone marrow for YFP expression (left plot). LSK cells were gated (box, middle plot) and analyzed for YFP expression (right plot). (D) FACS analysis of whole E13.5 fetal liver (left plot). LSK cells were gated (box, middle plot) and analyzed for YFP expression (right plot). Numbers in the top right-hand corner of the plots indicate the percentage of YFP⁺ cells in the respective cell population. FSC, forward scatter. (E) Comparison of the hematopoietic labeling of vav ancestry and lysozyme ancestry mice. The circles represent cell compartments: L, lymphoid; M, myelomonocytic and HSC, hematopoietic stem cells. Yellow indicates that the cells in a given compartment are YFP labeled, grey that they are unlabeled. The yellow triangles indicate that a subset of cells in the corresponding compartment is YFP⁺.