title: cdx4/lacZ and cdx2/lacZ protein gradients formed by decay during gastrulation in the mouse.
abstract: Expression of the mouse caudal genes cdx4 and cdx2 is examined by use of lacZ reporter constructs expressed in transgenic mouse embryos. During early gastrulation, up to at least 8.5 days of development, reporter mRNA distributions are apparently similar to those of endogenous cdx mRNAs. By 8.25 to 8.8 days, cdx/lacZ protein activities have become distributed as posterior-to-anterior gradients along the neural and mesoderm tissues. The gradients form by decay of activity as cells become distanced from the regressing tailbud. In situ hybridization studies indicate that the decay is primarily in cdx/lacZ protein activities rather than mRNAs. As gastrulation proceeds, the locations of the gradients regress progressively posteriorly along the growing axis. Our results indicate how cdx4 and cdx2 protein gradients might be generated by decay during normal development. The smoothness of the gradients that we detect shows that there cannot be extensive mixing of cells once they leave the tailbud to contribute to the growing axis. An enhancer element located in the first intron of the cdx4 gene is essential for correct transgene expression.
authors.affiliation: Department of Development and Genetics, The Babraham Institute, Cambridge, UK. stephen.gaunt@bbsrc.ac.uk
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Gaunt
authors.forename: Deborah
authors.initials: D
authors.lastname: Drage
authors.forename: Richard C
authors.initials: RC
authors.lastname: Trubshaw
mesh_terms: D000818:Animals; D000071616:CDX2 Transcription Factor; D005775:Gastrula / Q000378:metabolism*; D018398:Homeodomain Proteins / Q000096:biosynthesis* / Q000235:genetics; D017403:In Situ Hybridization; D007763:Lac Operon / Q000235:genetics; D051379:Mice; D008822:Mice, Transgenic; D012333:RNA, Messenger / Q000378:metabolism; D014157:Transcription Factors / Q000096:biosynthesis* / Q000235:genetics; D019076:Transgenes
chemical_list: D000071616:CDX2 Transcription Factor; C491272:Cdx1 protein, mouse; C487514:Cdx2 protein, mouse; C084563:Cdx4 protein, mouse; D018398:Homeodomain Proteins; D012333:RNA, Messenger; D014157:Transcription Factors