XB-ART-10511Mech Dev 2000 Aug 01;961:125-8. doi: 10.1016/s0925-4773(00)00379-8.
Show Gene links Show Anatomy links
Regional gene expression in the epithelia of the Xenopus tadpole gut.
In recent years much progress has been made in the understanding of the genes and mechanisms involved in specification of the cells of the endoderm, which give rise to the epithelium of the gut and respiratory system. However, little is known about the way in which the gut becomes patterned along its anterior-posterior axis, that is, how boundaries are established between the different epithelia of the gut tube. Here we show that the expression patterns of five genes divide the Xenopus tadpole gut epithelium into at least four regions along this axis in the undifferentiated, 3-day-old gut (stage 41), and that these divisions are maintained until at least 7 days, when cell differentiation is well under way. In addition, the restricted expression patterns of these genes clearly mark the anterior and posterior boundaries of the intestine. Xsox2 is expressed in the anterior gut, spanning the oesophagus and stomach but terminating at the stomach/intestine boundary. Xcad1 and Xcad2, two caudal-type homeobox genes, are expressed in a region with an anterior limit at this boundary and a posterior limit between the colon and proctodeum, therefore covering the whole of the small and large intestines. Intestinal fatty acid binding protein (IFABP) is expressed only in the anterior small intestine, and the even-skipped homeobox gene Xhox3 is expressed in the most posterior part of the gut, the proctodeum.
PubMed ID: 10940633
Article link: Mech Dev
Species referenced: Xenopus
Genes referenced: cad cdx1 cdx2 evx1 fabp2 sox2
Article Images: [+] show captions
|Fig. 1. Expression of regional epithelial markers in 3-day (stage 41) guts. In situ hybridization of 3-day Xenopus guts showing regional expression of markers along the anterior–posterior axis of the epithelium (dark blue). (A) Xsox2 anterior and posterior domains. (B) IFABP in the small intestine. (C) Xcad1 expression extends further posterior than IFABP, but not into the proctodeum. (D) Xcad2 expression is identical to that of Xcad1 in the gut. (E) Xhox3 marks the most posterior region of the gut, the proctodeum. (F) Regionalization of the 3-day gut based on the expression of these markers. Pa, pancreas; li, liver; st, stomach.|
|Fig. 2. Regionalization of the gut epithelium along the anterior-posterior axis at 7 days of development (stage 46/47). In situ hybridization to 7-day Xenopus guts showing regional expression of markers along the anterior posterior axis of the epithelium (dark blue). Left column shows the entire gut, centre column the anterior boundary (if appropriate) and the right column the posterior boundary. (A–C) Xsox2 (arrow 1 marks the stomach/transitional zone boundary and arrow 2 marks the boundary between the transitional zone and intestine). (D–F) IFABP. (G–I) Xcad 1. (J–L) Xcad 2. (M–O) Xhox3. (P) Schematic of the gut at 7 days showing the position of expression boundaries relative to differentiated tissue boundaries. Pa, pancreas; li, liver; g, gall bladder; st, stomach; si, small intestine; co, colon; pr, proctodeum.|