Fig. 2

Disrupted epithelial architecture, abnormal IEC and increased luminal bacteria in hi559 intestine. (A) In hi559 anterior GI tract, the IECs appear less columnar, a few IECs detach from the mucosa (arrowheads) and the esophageal GCs (arrows) appear disorganized with nuclear pyknosis. Asterisks indicate luminal bacterial plaques. (B) TEM comparison of intestinal epithelium of 6-dpf wild type (WT, left) and hi559 (right). Wild-type intestine shows columnar IECs, thick terminal web (tw; red line) and long microvilli (mv; arrows). hi559 IECs have thinner terminal webs, shorter microvilli and increased cytoplasmic vacuoles (asterisks). (C) TEM showing dense bacterial colonies in hi559 intestinal lumen (red arrows), but not in wild type. Bar chart (right) shows significant increase in intestinal bacterial density in hi559 (n=5). (D,E) The mucin-rich esophageal GCs (arrows) at 5 dpf (D) and 6 dpf (E) are shown by PAS staining (pink). The secreted mucinous layer (arrowhead) on the epithelial border seen in the wild type is diminished in hi559 with frequent detachment of GCs. Asterisks indicate luminal bacterial plaques. (F) Bar charts showing PAS-positive GC numbers in 5- and 6-dpf wild-type and hi559 esophagus (left; n=7) and the percentage of larvae with intra-luminal bacterial overgrowth at 5 and 6 dpf (right; ne21). Es, esophagus; Ib, intestinal bulb. *P<0.05, **P<0.01. Scale bars: 20 µM (A,D,E); 500 nm (B,C).