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27 Cards in this Set
- Front
- Back
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Double induction
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The synergism between Nodal and Wnt signaling in order to induce the organizer; act on animal hemisphere cells; both needed to get organizer, or else no organizer forms; the two pathways intersect!
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B-catenin/Tcf transcription factor
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Derepresses (stops repressing) several genes for TFs in order to help the organizer form
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Siamois
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Unrepressed by B-catenin/Tcf; activates Xnr3 and chordin genes, which encode Bmp antagonists-->helps form organizer
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Xnr3
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Gene that encodes Bmp antagonists; activated by Siamois-->helps organizer formation
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Chordin
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Gene that encodes Bmp antagonists; activated by Siamois-->helps organizer formation
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Iroquois
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Unrepressed by B-catenin/Tcf; encodes transcriptional repressor that represses bmp2, bmp4, and wnt8
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Wnt 8
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Similar function as Bmp, inhibits induction of the organizer by Nodal signals
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Bmp signaling
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Inhibits the induction of the organizer by Nodal signals
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Noggin
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Anti-Bmp; also secreted by organizer; a marker for it
-if a dorsalized phenotype, noggin expressed all over gastrula; if ventralized, no noggin expressed |
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dkk
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Anti-Wnt
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frzb
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Anti-Wnt
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Goosecoid
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Activates numerous genes in the organizer
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Gastrulation
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Formation of the gut; internalization of the endoderm and mesoderm, including the organizer
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Neurulation
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Formation of the nervous system; internalization of the dorsal hollow neural tube
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Blastocoel
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Role is to provide a separation between the animal cap cells and the vegetal cells so that the animal cap cells are not induced to form mesoderm because too far to receive the Nodal signal; also creates a space into which cells can move during gastrulation
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Tight junction
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Prevents passage of most solutes; outer layers of apposing bilayers fuse
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Adherens junction
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Contain transmembrane cadherins connected inside the cell to actin microfilaments; may provide strength, serve in cell-cell communication and support apical constriction (myosin mediated)
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Desmosomes
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Connected to intermediate filaments, probably give mechanical strength
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Gap junction
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Lets molecules of less than 1000 daltons pass directly between cells
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Exogastrulation
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When the mesoderm and endoderm do not move inside to form the blastocoel; occurs when there is a hyperosmotic medium outside of the cell (like 250mM sucrose); egg looks like a bowling pin
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Archenteron
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The primitive gut that forms during gastrulation in the developing blastula; this develops into the digestive tract of the animal
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Limit of involution
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Line that goes horizontally across egg; shows how the ectoderm is expanding and the rest is "shrinking"(?) during gastrulation
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Truncated II
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The subunit II of a Nodal or Bmp receptor that will not activate the kinase of subunit I; Smad2/3 (if Nodal pathway) cannot be phosphorylated without the activated kinase subunit I-->thus, it cannot be activated
=a dominant negative strategy for blocking Nodal or Bmp signaling |
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Blastodisc
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Aka germinal disc; a disc-shaped layer of cytoplasm that is formed at the animal pole by cleavage of a large, yolky egg
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Epiblast
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A tissue type derived from the blastodisc; lies above the hypoblast; differentiates to form all three germ layers (ectoderm, mesoderm, and endoderm)
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Hypoblast
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The embryonic precursor to the endoderm; lies beneath the epiblast and consists of small cuboidal cells; the endoderm (which comes from the epiblast) displaces the hypoblast cells; the absence of the hypoblast results in multiple primitive streaks in chicken embryos
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Endoblast
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Becomes the endoderm
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