1) Figure 1 illustrates a hypothetical gene regulatory network necessary therefo
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Question
1) Figure 1 illustrates a hypothetical gene regulatory network necessary therefore development of the embryonic urchin skeleton. for specification ot microenes anu Rpl is normally lineage and is NOT expressed in the NON-skeletogenic lineage (all other cell types). 24 points Rpl a) What genes in this network are normally expressed in the skeletogenic lineage? sk1 sk2 sk3 Figure 1. b) If you knockdown Rp1 via morpholinos (MASO), what genes would be expressed in the skeletogenic lineage? Repressed? How would this affect ingression, the first stage of gastrulation? c) If you overexpress Rp1 in the whole embryo through mRNA overexpression (MOE) how would this affect gene expression in the NON-skeletogenic lineage (all other cells), what genes would be expressed and repressed in this lineage? How would this affect ingression, the first stage of gastrulation?Explanation / Answer
Answer 1. a)
Rp1 represses Rp2. As a result, genes Sk1, Sk2 and Sk3 are produced. Sk1 and Sk2 further produce Sk4.
b)
If Rp1 is knocked down, then Rp2 will be produced. As a result Sk1, Sk2, Sk3 and Sk4 will be repressed.
Sk is a potassium channel. Its activity is important in the differentiation of embryonic stem cells (ESCs). Sk4 is predominantly important because it functions in cardiac development from the ES cells. So, if Rp1 is knocked down, then ES cell differentiation will be stopped. Ingression will also be stopped.
Note that ingression is the first stage of gastrulation. It results in movement of cells of the blastula; this finally causes the formation of mesenchyme. (The mesenchyme further forms the mesoderm, which further forms most of the systems of the body).
c)
Overexpression of Rp1 in the entire embryo has been done. This activates Cdc42 and Rac1; this will induce morphological changes in MDCK cells. Excess Rp1 also localizes at the tips of lamellipodia of migrating cells. Ingression is highly increased.
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