title: Specification of endoderm in the sea urchin embryo.
abstract: Expression of the endoderm specific gene Endo16, was used to monitor endoderm specification in developmentally arrested and in dissociated embryos. beta-APN treatment halts gastrulation, however, in two species of sea urchins Endo16 mRNA is still expressed, suggesting that specification of the endodermal lineage has taken place in these developmentally arrested embryos. Endo16 mRNA is not expressed in embryos dissociated at the 4-8-cell stage unless they are reassociated shortly after the 16-cell stage. Interestingly, dissociation after the 16-cell stage also results in a lack of Endo16 expression. Lithium is unable to rescue Endo16 expression in these dissociated embryos. These results indicate that early signaling events mediated by cell-cell contact are required for the initial specification and maintenance of the endoderm in the developing embryo.
authors.affiliation: Department of Biology, Tufts University, Medford, MA 02155, USA.
authors.forename: R E
authors.initials: RE
authors.lastname: Godin
authors.forename: D C
authors.initials: DC
authors.lastname: Klinzing
authors.forename: W A
authors.initials: WA
authors.lastname: Porcaro
authors.forename: S G
authors.initials: SG
authors.lastname: Ernst
mesh_terms: D000595:Amino Acid Sequence; D000629:Aminopropionitrile / Q000494:pharmacology; D000818:Animals; D001483:Base Sequence; D002135:Calcium-Binding Proteins / Q000187:drug effects / Q000235:genetics; D015815:Cell Adhesion Molecules / Q000235:genetics; D002450:Cell Communication; D004625:Embryo, Nonmammalian / Q000187:drug effects / Q000502:physiology*; D004707:Endoderm / Q000187:drug effects / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D008094:Lithium / Q000494:pharmacology; D008969:Molecular Sequence Data; D011506:Proteins / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis / Q000187:drug effects; D012617:Sea Urchins / Q000196:embryology*
chemical_list: D002135:Calcium-Binding Proteins; D015815:Cell Adhesion Molecules; D011506:Proteins; D012333:RNA, Messenger; C094296:Spec1 protein, Strongylocentrotus purpuratus; C061515:endo16 protein, sea urchin; D000629:Aminopropionitrile; D008094:Lithium