Dietary cystine restriction increased the amount of goblet cells in the colon.

A) Representative images of the secreted mucus layer visualized by a High Iron Diamine (HID) staining (scalebar = 200 μm). Arrows indicate mucus layer thickness. B) Quantification of the secreted mucus layer (n = 4 for normal cys; n = 3 for low cys, average of 12 measurements per mouse ± SEM are depicted, Mann-Whitney test). C) Quantification of Muc2-positive goblet cells, per crypt (n = 8/group, mean ± SEM, unpaired t-test, *p<0.05). D) Permeability of the distal colonic mucus layer was visualized by adding 1-lm fluorescent beads (red) to the epithelial tissue (green). Shown are representative maximum projections of a resliced z-stack, showing a summarized view of the sample from the side. Arrows indicate distance. E) The distance between the beads and the epithelium was measured and depicted for 4 mice per group (Each dot represents one bead). F) PCA plot for the diversity of the small intestinal microbiome. Each dot represents one mouse (n = 7/group). G) Relative abundance of microbiota in the small intestinal contents at the g (genus), f (family), c (class) level in individual samples (mice were individually housed). H) PCA plot for the diversity of the colonic microbiome. Each dot represents one mouse (n = 8/group). I) Relative abundance of microbiota in the colonic contents at the g (genus), f (family), c (class) level in individual samples (mice were individually housed).