control of gene expression
Terms
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- Nieukoop center
- (frogs) Group of dorsal vegetal blastomeres that can induce formation of dorsal mesoderm
- disheveled
- (frogs) Contained in granules in oocyte; after fertilization, diffuses to form gradient, de-activates GSK3
- GSK3
- (frogs) Breaks down beta-catenin; not localized in oocyte
- beta-catenin
- (frogs) Transcription factor; lots of b-c mRNA in oocyte, fertilization --> lots of delocalized b-c protein; broken down by GSK3; makes cells dorsal
- siamois/twin
- (frogs) Turned on by beta-catenin
- veg1 & vegT
- (frogs) Mesoderm-inducing; mRNA localized in oocyte & expressed after fertilization
- frog organizer cells
- siamois/twin & veg1/vegT makes a cell be organizer; cell then expresses goosecoid gene & nodal genes
- frog organizer function
- initiate gastrulation (become bottle cells, migrate under ectoderm in involution); dorsalize surrounding tissue; differentiate into notochord, establish anterior/posterior axis of embryo
- induction of neural tube in frogs
- negative induction
- frog organizer signals
- diffusible molecules: chordin, noggin, follistatin
- frog ventral signal
- BMP4 actively causes ventralization (dorsal is default); chordin, noggin & follistatin block BMP4 to dorsalize
- A
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