title: Molecular components of the endoderm specification pathway in Xenopus tropicalis.
abstract: Xenopus laevis has been instrumental in elucidating a conserved molecular pathway that regulates vertebrate endoderm specification. However, loss-of-function analysis is required to resolve the precise function of the genes involved. For such analysis, antisense oligos and possibly forward genetics are likely to be more effective in the diploid species Xenopus tropicalis than in the pseudotetraploid Xenopus laevis. Here we have isolated most of the tropicalis genes in the endoderm specification pathway, specifically, tVegT, tMixer, tMix, tBix, tGata6, tSox17alpha, tSox17beta, tFoxA1, tHex, and tCerberus, which lack the redundant copies that are found in laevis. In situ hybridization analysis has revealed identical expression patterns between the orthologous tropicalis and laevis endoderm genes, thus suggesting conserved genetic functions. Furthermore, we noted that the smaller tropicalis embryos gave better probe penetration than in laevis whole-mount in situ hybridizations-allowing us to visualize transcripts in the deep endoderm in tropicalis, which is difficult in laevis. This study illustrates how an entire genetic pathway can be quickly transferred from laevis to tropicalis due to high sequence conservation between the sister species and the large number of tropicalis-expressed sequence tags that are now available.
authors.affiliation: Cincinnati Children's Hospital Medical Center, Division of Developmental Biology, Cincinnati, Ohio 45229-3039, USA.
authors.forename: Anjali
authors.initials: A
authors.lastname: D'Souza
authors.forename: Monica
authors.initials: M
authors.lastname: Lee
authors.forename: Nicola
authors.initials: N
authors.lastname: Taverner
authors.forename: Julia
authors.initials: J
authors.lastname: Mason
authors.forename: Samantha
authors.initials: S
authors.lastname: Carruthers
authors.forename: James C
authors.initials: JC
authors.lastname: Smith
authors.forename: Enrique
authors.initials: E
authors.lastname: Amaya
authors.forename: Nancy
authors.initials: N
authors.lastname: Papalopulu
authors.forename: Aaron M
authors.initials: AM
authors.lastname: Zorn
mesh_terms: D000818:Animals; D001425:Bacterial Outer Membrane Proteins / Q000096:biosynthesis; D002454:Cell Differentiation; D019070:Cell Lineage; D018076:DNA, Complementary / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000096:biosynthesis; D004707:Endoderm / Q000378:metabolism*; D050993:GATA6 Transcription Factor; D015723:Gene Library; D006609:High Mobility Group Proteins; D018398:Homeodomain Proteins / Q000096:biosynthesis; D017874:Immediate-Early Proteins / Q000096:biosynthesis; D017403:In Situ Hybridization; D036341:Intercellular Signaling Peptides and Proteins; D014176:Protein Biosynthesis; D011506:Proteins; D012333:RNA, Messenger / Q000378:metabolism; D055760:SOXF Transcription Factors; D013045:Species Specificity; D020825:T-Box Domain Proteins / Q000096:biosynthesis; D014157:Transcription Factors / Q000096:biosynthesis; D014981:Xenopus / Q000196:embryology* / Q000235:genetics*; D029867:Xenopus Proteins
chemical_list: D001425:Bacterial Outer Membrane Proteins; C115868:Bix1 protein, Xenopus; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D050993:GATA6 Transcription Factor; C494758:GATA6 protein, Xenopus; D006609:High Mobility Group Proteins; D018398:Homeodomain Proteins; D017874:Immediate-Early Proteins; D036341:Intercellular Signaling Peptides and Proteins; D011506:Proteins; D012333:RNA, Messenger; D055760:SOXF Transcription Factors; D020825:T-Box Domain Proteins; D014157:Transcription Factors; C103966:VegT protein, Xenopus; D029867:Xenopus Proteins; C100866:cer1 protein, Xenopus; C513078:hhex protein, Xenopus; C491602:sox17a protein, Xenopus; C491601:sox17b.1 protein, Xenopus