Spemann
Mostrando 1-12 de 17 artigos, teses e dissertações.
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1. HEIDEGGER E OS LIMITES DA MATEMATIZAÇÃO NO CONHECIMENTO DOS ORGANISMOS VIVOS
RESUMO No Curso de Inverno de 1928/29, Heidegger afirmou que a matematização irrestrita no conhecimento dos seres vivos resultaria numa falha no propósito de elaborar a ontologia da vida orgânica. No presente artigo, examino as razões que justificam essa concepção. Com base em interpretações das investigações de biólogos como Hans Driesch J. v. U
Kriterion. Publicado em: 2017-12
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2. Siamois is required for formation of Spemann’s organizer
Spemann’s organizer develops in response to dorsal determinants that act via maternal components of the wnt pathway. The function of siamois, a wnt-inducible homeobox gene, in Spemann’s organizer development was examined by fusion of defined transcriptional regulatory domains to the siamois homeodomain. Similar to native siamois, a VP16 activator fusion
The National Academy of Sciences of the USA.
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3. MEDAL REVIEW: The Spemann organizer and embryonic head induction
Oxford University Press.
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4. The heritage of experimental embryology: Hans Spemann and the organizer
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5. Antagonizing the Spemann organizer: role of the homeobox gene Xvent-1.
We have identified a novel homeobox gene, Xvent-1, that is differentially expressed in the ventral marginal zone of the early Xenopus gastrula. Evidence is presented from mRNA microinjection experiments for a role for this gene in dorsoventral patterning of mesoderm. First, Xvent-1 is induced by BMP-4, a gene known to be a key regulator of ventral mesoderm d
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6. Competition between noggin and bone morphogenetic protein 4 activities may regulate dorsalization during Xenopus development.
Bone morphogenetic protein 4 (BMP-4) induces ventral mesoderm but represses dorsal mesoderm formation in Xenopus embryos. We show that BMP-4 inhibits two signaling pathways regulating dorsal mesoderm formation, the induction of dorsal mesoderm (Spemann organizer) and the dorsalization of ventral mesoderm. Ectopic expression of BMP-4 RNA reduces goosecoid and
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7. Antagonistic actions of activin A and BMP-2/4 control dorsal lip-specific activation of the early response gene XFD-1' in Xenopus laevis embryos.
Transcription of the early response gene XFD-1' (XFKH1) in the dorsal lip (Spemann organizer) of Xenopus embryos is activated by dorsal mesoderm inducing factors. Promoter studies revealed the presence of an activin A response element (ARE) which is both necessary and sufficient for transcriptional activation of reporter genes in animal cap explants incubate
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8. Neural Induction in Xenopus: Requirement for Ectodermal and Endomesodermal Signals via Chordin, Noggin, β-Catenin, and Cerberus
The origin of the signals that induce the differentiation of the central nervous system (CNS) is a long-standing question in vertebrate embryology. Here we show that Xenopus neural induction starts earlier than previously thought, at the blastula stage, and requires the combined activity of two distinct signaling centers. One is the well-known Nieuwkoop cent
Public Library of Science.
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9. Dkk1 and noggin cooperate in mammalian head induction
Growth factor antagonists play important roles in mediating the inductive effects of the Spemann organizer in amphibian embryos and its equivalents in other vertebrates. Dual inhibition of Wnt and BMP signals has been proposed to confer head organizer activity. We tested the requirement of this coinhibition in Xenopus and mice. In Xenopus, simultaneous reduc
Cold Spring Harbor Laboratory Press.
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10. A novel homeobox gene, dharma, can induce the organizer in a non-cell-autonomous manner
The formation of Spemann organizer is one of the most important steps in dorsoventral axis determination in vertebrate development. However, whether the organizer forms autonomously or is induced non-cell-autonomously is controversial. In this report we have isolated a novel zebrafish homeobox gene, dharma, capable of inducing the organizer ectopically. The
Cold Spring Harbor Laboratory Press.
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11. Retinoic acid is enriched in Hensen's node and is developmentally regulated in the early chicken embryo.
Retinoic acid (RA) has been considered as a potential morphogen in the chicken limb and has also been suggested to be involved in early embryonic development. On the basis of biological activity, previous reports suggest that Hensen's node, the anatomical equivalent in the chicken of the Spemann's organizer, may contain RA. Here, by using a molecular assay s
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12. Endoderm induction by the organizer-secreted factors chordin and noggin in Xenopus animal caps.
Spemann's organizer has potent neural inducing and mesoderm dorsalizing activities in the Xenopus gastrula. A third activity, the organizer's ability to induce a secondary gut, has been difficult to analyze experimentally due to the lack of early gene markers. Here we introduce endodermin, a pan-endodermal gene marker, and use it to demonstrate that chordin