Fig. 4
Dietary fiber deficiency for 15 weeks impaired the intestinal barrier and induced intestinal inflammation and microbiota alteration. A The quantification of the colonic mucus layer was statistically analyzed (2 sections per animal, n = 5). B Alcian blue-stained colonic sections were showing the mucus layer (arrows). Opposing black arrows with shafts delineate the mucus layer that was measured. Scale bar: 50 μm. C Immunofluorescence images of colonic sections stained with MUC2 (green) and DAPI (blue). Opposing white arrows with shafts delineate the mucus layer. Scale bar: 50 μm. D Quantitation of colonic Reg3γ by RT-PCR (n = 6). (E) FISH analysis of the colon sections using the general bacterial probe EUB338-Alexa Fluor 488 (green) and nuclear staining DAPI (blue). Arrows indicate the distance between bacteria and epithelium. Scale bar: 10 μm. F Protein expression levels of occludin and ZO-1 in the colon (n = 5). G Fecal albumin concentrations (n = 8). H Serum endotoxin level (n = 10). I The quantification of colon length was statistically analyzed (n = 9) and representative images of colons. J Principal coordinates analysis plot of bray distances of the cecal microbiome. K, L Composition of abundant bacterial phyla. M The association between gut microbiota and cognitive behaviors. Totally, we identified 25 microbiota responsible for discriminating the FD and control groups using linear discriminant analysis (LDA > 2.0). The intensity of color in the middle heatmap (blue to red) indicates the normalized abundance score for each microbiota. The size and color of each point in the scatter plot show the p values of Spearman’s correlation (ranging from 6.62e−8 to 0.80) and values of correlation coefficient (ranging from − 0.94 to 0.98) between differential microbiota and cognitive behaviors, respectively. N Predicted KEGG functional pathway differences at level 3 inferred from 16S rRNA gene sequences using PICRUSt. Values are mean ± SEM. *p < 0.05 fiber deficiency (FD) group vs. control (Con) group. Abbreviations: p, phylum