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.
Developmental Biology Programme, Department of Biology and Biochemistry, University of Bath, BA2 7AY, Bath, UK.
A D
AD
Chalmers
J M
JM
Slack
C W
CW
Beck
D000818:Animals; D030161:Avian Proteins; D000071616:CDX2 Transcription Factor; D002352:Carrier Proteins / Q000096:biosynthesis; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics; D004848:Epithelium / Q000196:embryology* / Q000378:metabolism; D004947:Esophagus / Q000196:embryology / Q000378:metabolism; D050556:Fatty Acid-Binding Proteins; D005753:Gastric Mucosa / Q000378:metabolism; D015870:Gene Expression; D024002:HMGB Proteins; D018398:Homeodomain Proteins / Q000096:biosynthesis / Q000235:genetics; D017403:In Situ Hybridization; D007413:Intestinal Mucosa / Q000378:metabolism*; D007422:Intestines / Q000196:embryology*; D008954:Models, Biological; D009363:Neoplasm Proteins; D009687:Nuclear Proteins / Q000096:biosynthesis / Q000235:genetics; D055748:SOXB1 Transcription Factors; D013270:Stomach / Q000196:embryology; D013997:Time Factors; D015534:Trans-Activators; D014157:Transcription Factors; D014981:Xenopus / Q000196:embryology* / Q000378:metabolism; D029867:Xenopus Proteins
D030161:Avian Proteins; C491273:CDX1 protein, human; D000071616:CDX2 Transcription Factor; D002352:Carrier Proteins; C491272:Cdx1 protein, mouse; D004268:DNA-Binding Proteins; C094040:EVX1 protein, Xenopus; D050556:Fatty Acid-Binding Proteins; D024002:HMGB Proteins; D018398:Homeodomain Proteins; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D055748:SOXB1 Transcription Factors; C527783:Sox2 protein, mouse; D015534:Trans-Activators; D014157:Transcription Factors; D029867:Xenopus Proteins; C000605378:cdx2 protein, Xenopus; C493314:intestinal fatty acid binding protein, Xenopus; C527781:sox2 protein, Xenopus