How would you expect embryos to develop? Include way to test effects and control
ID: 55366 • Letter: H
Question
How would you expect embryos to develop? Include way to test effects and control.
a) Inject morpholinos targeting the genes siamois and twin at the two-cell stage and then allow development to proceed through the beginning of organogenesis (neural).
b) Inject a fertilized Xenopus egg with messenger RNA encoding a constitutively active BMP receptor. At the blastula stage, remove the animal cap and culture it in the presence of noggin protein. (Constitutively active = always on)
c)Block the cortical rotation of a fertilized Xenopus egg, then, at the 4-cell stage, inject -catenin mRNA into two cells, on opposite sides of the embryo and allow development to proceed through the gastrulation period.
Explanation / Answer
A.morpholino is used to to modify gene expression.In response to stabilized catenin, dorsal blastomeres express the closely related transcriptional activators, Siamois (Sia) and Twin (Twn), members of the paired homeobox family. Sia and Twn induce organizer formation and expression of organizer-specific genes, including Goosecoid (Gsc). In spite of the similarity of Sia and Twn sequence and expression pattern, it is unclear whether these factors function equivalently in promoter binding and subsequent transcriptional activation, or if Sia and Twn are required for all aspects of organizer function.
B.Noggin protein:nerve tissue, muscles, and bones. In humans is encoded by the NOG gene.The secreted polypeptide noggin, encoded by the NOG gene, binds and inactivates members of the transforming growth factor-beta (TGF-beta) superfamily signaling proteins, such as bone morphogenetic protein-4 (BMP4).
C.-catenin speeds up S phase in endomesoderm at MBT.slows down interphase in endoderm at EGT.-catenin dependant-transcription patterns the cell cycle.
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