title: Transcription factors Mix1 and VegT, relocalization of vegt mRNA, and conserved endoderm and dorsal specification in frogs.
abstract: Protein expression of the transcription factor genes mix1 and vegt characterized the presumptive endoderm in embryos of the frogs Engystomops randi, Epipedobates machalilla, Gastrotheca riobambae, and Eleutherodactylus coqui, as in Xenopus laevis embryos. Protein VegT was detected in the animal hemisphere of the early blastula in all frogs, and only the animal pole was VegT-negative. This finding stimulated a vegt mRNA analysis in X. laevis eggs and embryos. vegt mRNA was detected in the animal region of X. laevis eggs and early embryos, in agreement with the VegT localization observed in the analyzed frogs. Moreover, a dorso-animal relocalization of vegt mRNA occurred in the egg at fertilization. Thus, the comparative analysis indicated that vegt may participate in dorsal development besides its known roles in endoderm development, and germ-layer specification. Zygotic vegt (zvegt) mRNA was detected as a minor isoform besides the major maternal (mvegt) isoform of the X. laevis egg. In addition, α-amanitin-insensitive vegt transcripts were detected around vegetal nuclei of the blastula. Thus, accumulation of vegt mRNA around vegetal nuclei was caused by relocalization rather than new mRNA synthesis. The localization of vegt mRNA around vegetal nuclei may contribute to the identity of vegetal blastomeres. These and previously reportedly localization features of vegt mRNA and protein derive from the master role of vegt in the development of frogs. The comparative analysis indicated that the strategies for endoderm, and dorsal specification, involving vegt and mix1, have been evolutionary conserved in frogs.
authors.affiliation: Department of Biological Sciences, Graduate School of Science, University of Tokyo, Tokyo 113-0033, Japan; Department of Anatomy, School of Medicine, Tokyo Women's Medical University, Tokyo 162-8666, Japan;
authors.forename: Norihiro
authors.initials: N
authors.lastname: Sudou
authors.affiliation: Escuela de Ciencias Biológicas, Pontificia Universidad Católica del Ecuador, Quito 170517, Ecuador.
authors.forename: Andrés
authors.initials: A
authors.lastname: Garcés-Vásconez
authors.affiliation: Escuela de Ciencias Biológicas, Pontificia Universidad Católica del Ecuador, Quito 170517, Ecuador.
authors.forename: María A
authors.initials: MA
authors.lastname: López-Latorre
authors.affiliation: Department of Biological Sciences, Graduate School of Science, University of Tokyo, Tokyo 113-0033, Japan;
authors.forename: Masanori
authors.initials: M
authors.lastname: Taira
authors.affiliation: Escuela de Ciencias Biológicas, Pontificia Universidad Católica del Ecuador, Quito 170517, Ecuador edelpino@puce.edu.ec.
authors.forename: Eugenia M
authors.identifier: 0000-0002-4678-7852
authors.initials: EM
authors.lastname: Del Pino
mesh_terms: D053959:Alpha-Amanitin / Q000494:pharmacology; D000818:Animals; D019521:Body Patterning; D004707:Endoderm / Q000502:physiology*; D018398:Homeodomain Proteins / Q000032:analysis / Q000502:physiology*; D012333:RNA, Messenger / Q000378:metabolism*; D020825:T-Box Domain Proteins / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D014157:Transcription Factors; D029867:Xenopus Proteins / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D014982:Xenopus laevis / Q000196:embryology*
chemical_list: D053959:Alpha-Amanitin; D018398:Homeodomain Proteins; C100368:Mix1 protein, Xenopus; D012333:RNA, Messenger; D020825:T-Box Domain Proteins; D014157:Transcription Factors; C103966:VegT protein, Xenopus; D029867:Xenopus Proteins
keywords: blastula; gastrula; germ plasm; mvegt; zvegt