FIGURE 3.

In vivo transfer of bacterial Cre to mucosal host cells. (a) Experimental set up of in vivo experiments. (b+c) Representative data derived from the intestinal tissue of Rosa26.tdTomato mice treated with either E. coli ^Cre plus E. coli ^GFP (n = 9) or with E. coli ^GFP only (n = 5). Experiments were performed in three independent experiments with similar results. (b) Representative confocal images of small intestinal (Ileum) cryo‐cross sections showing tdTomato‐positive epithelial cells (red) and E. coli ^GFP (green). Nuclei counterstaining with Hoechst (blue). Scale bar: 100 μm; Magnification, Scale bar: 10 μm. (c) Representative images of small intestinal and colonic cross‐sections demonstrating tdTomato‐positive cells (red) and E. coli ^GFP (green). Inset: Higher magnification of the stem cell region. Nuclei counterstaining with Hoechst (blue). Scale bar: 100 μm. (d) Volumetric reconstruction images of Rosa26.tdTomato intestinal mucosa treated with E. coli ^Cre showing red‐to‐white gradient with tdTomato signal in crypts (red), as well as collagen (SHG; grey), epithelial cells (EpCAM; grey), LYVE1 (green), and WGA (blue). Total analysis of 10,000 ileal crypts derived from Rosa26.tdTomato mice treated with E. coli ^Cre (n = 3). Scale bar: 100 μm. (e) Quantification of tdTomato‐positive crypts per sample area. (f) Representative immunohistochemical images of small intestinal (Ileum) cryo‐cross sections of Rosa26.tdTomato mice treated with E. coli ^Cre or PBS as control. Confocal pictures visualized tdTomato‐positive cells (red) and staining against Paneth cells (Lyz, Green). Nuclei counterstaining with Hoechst (blue). Scale bar: 100 μm. (g) Representative confocal images of organoids derived from the small and large intestine of Rosa26.tdTomato mice colonized with E. coli ^Cre (right) or as a control E. coli ^GFP (left) 6 days after isolation. Scale Bar: 50 μm. Experiments were repeated three times with similar results