Figure 2

Claudin 7 immunohistochemistry in the mammary gland. (a) Western blot on 50 μg of protein from mammary gland at pregnancy days 7 and 18 (P7 and P18) and lactation days 2 and 9 (L2 and L9). Because gene expression is 20-fold lower at P7, as can be seen from Fig. 1a, protein would not be expected to be visible at this exposure. Right-hand side: section of gland from virgin mouse stained with antibody (Zymed) to Claudin 1. (b) Lower-power views of epithelial structures from the developmental stages indicated with fluorescein isothiocyanate-labeled ZO-1 (green), Cy3-labeled claudin 7 (red), and 4,6-diamidino-2-phenylindole-labeled nuclei (blue). Lu, lumen; adip, adipocyte. Lower right: anticlaudin antibody blocked with claudin 7 peptide. Scale bar, 30 μm. (c) High-power views of claudin 7 localization. The right-hand images show the merged views as in (b). The left-hand black-and-white images show only the claudin 7 stain, demonstrating clearly the punctate nature of the claudin 7 distribution near the basolateral membranes; claudin 7 is excluded from both nuclei and tight junctions. Scale bar, 10 μm. Arrows in all figures point to FITC-stained ZO-1 (green).