title: X-twi is expressed prior to gastrulation in presumptive neurectodermal and mesodermal cells in dorsalized and ventralized Xenopus laevis embryos.
abstract: Early X-twi expression has been now investigated from egg laying to the early neurulation stages in Xenopus embryos, using both in situ hydridization and the more sensitive techniques of RT-PCR. We show that in unfertilized eggs, a decreasing gradient of X-twi transcript distribution is observed from animal to vegetative caps. X-twi RNA can be weakly detected at stages prior to gastrulation, and with increased intensity from stage 8 onwards. At blastula, X-twi transcripts are located towards the animal pole, and as gastrulation begins, they are detected in the developing axial mesoderm and then they accumulate in the sensorial layer of the neurectoderm, the mesodermal layer and in neural crest cells up to late neurula stages. We show, in addition, that in lithium-chloride- and UV-treated Xenopus embryos (that are respectively both "anteriorized/dorsalized" and in "posteriorized/ventralized"), X-twi RNA is detected in cells in similar positions to those that express X-twi in normal embryos. As a whole, our results show that X-twi is expressed even when regionalization of the mesoderm is disturbed and raises the question of a putative function of X-twi prior to gastrulation.
authors.affiliation: Institut de Chimie Biologique, Faculté de Médecine, LGME-CNRS, U184-INSERM, Strasbourg, France.
authors.forename: C
authors.initials: C
authors.lastname: Stoetzel
authors.forename: A L
authors.initials: AL
authors.lastname: Bolcato-Bellemin
authors.forename: P
authors.initials: P
authors.lastname: Bourgeois
authors.forename: F
authors.initials: F
authors.lastname: Perrin-Schmitt
authors.forename: D
authors.initials: D
authors.lastname: Meyer
authors.forename: M
authors.initials: M
authors.lastname: Wolff
authors.forename: P
authors.initials: P
authors.lastname: Remy
mesh_terms: D000818:Animals; D001755:Blastocyst; D019521:Body Patterning; D004268:DNA-Binding Proteins / Q000235:genetics*; D004475:Ectoderm / Q000737:chemistry*; D005775:Gastrula; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D018021:Lithium Chloride / Q000494:pharmacology; D008648:Mesoderm / Q000737:chemistry*; D010063:Ovum / Q000737:chemistry; D012333:RNA, Messenger / Q000032:analysis; D051879:Twist-Related Protein 1; D014466:Ultraviolet Rays; D029867:Xenopus Proteins; D014982:Xenopus laevis
chemical_list: D004268:DNA-Binding Proteins; D012333:RNA, Messenger; D051879:Twist-Related Protein 1; D029867:Xenopus Proteins; C581761:twist basic helix-loop-helix transcription factor 1, Xenopus; D018021:Lithium Chloride