title: Novel gene expression patterns along the proximo-distal axis of the mouse embryo before gastrulation.
abstract: BACKGROUND
  To date, the earliest stage at which the orientation of the anterior-posterior axis in the mouse embryo is distinguishable by asymmetric gene expression is shortly after E5.5. At E5.5, prospective anterior markers are expressed at the distal tip of the embryo, whereas prospective posterior markers are expressed more proximally, close to the boundary with the extraembryonic region.
  
  
  RESULTS
  To contribute to elucidating the mechanisms underlying the events involved in early patterning of the mouse embryo, we have carried out a microarray screen to identify novel genes that are differentially expressed between the distal and proximal parts of the E5.5 embryo. Secondary screening of resulting candidates by in situ hybridisation at E5.5 and E6.5 revealed novel expression patterns for known and previously uncharacterised genes, including Peg10, Ctsz1, Cubilin, Jarid1b, Ndrg1, Sfmbt2, Gjb5, Talia and Plet1. The previously undescribed gene Talia and recently identified Plet1 are expressed specifically in the distal-most part of the extraembryonic ectoderm, adjacent to the epiblast, and are therefore potential candidates for regulating early patterning events. Talia and the previously described gene XE7 define a gene family highly conserved among metazoans and with a predicted protein structure suggestive of a post-transcriptional regulative function, whilst Plet1 appears to be mammal-specific and of unknown function.
  
  
  CONCLUSIONS
  Our approach has allowed us to compare expression between dissected parts of the egg cylinder and has identified multiple genes with novel expression patterns at this developmental stage. These genes are potential candidates for regulating tissue interactions following implantation.
authors.affiliation: The Wellcome Trust/Cancer Research UK Gurdon Institute of Cancer and Developmental Biology, Tennis Court Rd, Cambridge, UK. stephen@frankenberg.com.au <stephen@frankenberg.com.au>
authors.forename: Stephen
authors.initials: S
authors.lastname: Frankenberg
authors.forename: Lee
authors.initials: L
authors.lastname: Smith
authors.forename: Andy
authors.initials: A
authors.lastname: Greenfield
authors.forename: Magdalena
authors.initials: M
authors.lastname: Zernicka-Goetz
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000941:Antigens / Q000235:genetics; D001483:Base Sequence; D019521:Body Patterning / Q000235:genetics*; D004622:Embryo, Mammalian / Q000648:ultrastructure; D005775:Gastrula / Q000378:metabolism* / Q000648:ultrastructure; D020869:Gene Expression Profiling; D008562:Membrane Glycoproteins / Q000235:genetics; D051379:Mice; D008969:Molecular Sequence Data; D020411:Oligonucleotide Array Sequence Analysis; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
chemical_list: D000941:Antigens; D008562:Membrane Glycoproteins; D016601:RNA-Binding Proteins; C519461:Talia protein, mouse; C077916:AKAP17A protein, human