Figure 1.

The vav-iCre/LacZ reporter mouse reveals the contribution of hematopoietic cells to non-hematopoietic tissues. a, iCre is expressed under the control of the hematopoietic-specific vav-promoter in vav-iCre mice. Crossing vav-iCre mice with Cre reporter lines leads to the excision of a floxed stop codon in hematopoietic cells and subsequently to the expression of LacZ under the control of the lineage-independent ROSA26 promoter. Thus, reporter gene expression is maintained, irrespectively of changes in lineage-specific genes. b, FACS-analysis of mononucleated cells from peripheral blood of adult vaviCre/GFP mice for recombination frequency in CD45-positive cells. Fluorescence intensity for CD45-stain is indicated on the y-axis, for GFP, on the x-axis. The left panel shows a control mouse. On the right panel the analysis of peripheral blood from a double transgenic mouse is shown. High fluorescence intensity is observed in >95% of the cells. c, As in b, but showing the analysis for vaviCre/LacZ mice. Intracellular LacZ was stained by an antibody in fixed and permeabilized cells. The recombination frequency is >96%. d, Identification of a GFP-positive cell in the cerebellum of a vav-iCre/GFP reporter mouse, displaying the typical highly arborized morphology of a Purkinje neuron. e, Immunoreactivity for the Purkinje neuron specific marker calbindin (blue) and overlay of GFP and calbindin images (f). g, Identification of a LacZ-positive cell by X-gal enzymatic staining in the liver of a vav-iCre/LacZ reporter mouse. Confocal image of the same cell with (h) propidium iodide (red), LacZ-stain (blue), and albumin (green), overlay. i, Skeletal muscle with a LacZ-positive muscle fiber (blue), counterstained with hemalaun and eosin, and a LacZ positive cardiac muscle fiber in j. Scale bars: d, 20 μm; g, 10 μm; h, 5 μm; i, j, 25 μm.