10. Genetic mosaics are created within the proneural clusters in the background

Question

10. Genetic mosaics are created within the proneural clusters in the background of a heterozygous Notch-/+ organism.
One of the cells within such a cluster gets a Notch-/Notch- genotype.
Predict whether this cell will become a neuroblast or an epidermoblast. Briefly explain your answer. (2 pts)

11. A similar genetic mosaic experiment is conducted in a Delta-/+ background and now one cell within a cluster gets a Delta-/Delta- genotype. Predict whether this cell will become a neuroblast or an epidermoblast. Briefly explain your answer. (2 pts)

Explanation / Answer

Answer 10

In one cell having Notch- / Notch - genotype, So no notch signalling occurs in the cell / notch signalling inactive.

In cells, having Notch+ / Notch+ genotype, notch signalling will be active and proneural gene expression will be low which leads to the development of epidermoblast (Skin) from neuroectoderm cells.

Answer 11

In cell having Delta- / Delta- genotype, neuroepidermal cell will differentiate into epidermoblast.

One recent study indicates that when Delta and notch present within the same cell, one phenomena i.e cis-inhibition comes into play, where Delta inhibits the notch signalling, so when delta decreases, notch signalling increases which leads to low pro-neural genes expression which causes epidermoblast formation from neuroepidermal cell.

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