Question

In the species A of crustaceans, Ubx is expressed in segments 5-10. In the species B, the Ubx expression has expanded anteriorly and the gene is expressed in segments 4-10. The cis-regulatory regions of Ubx from the species A were cloned upstream of the GFP reporter, and transgenic lines containing this construct were generated for both species.

a) In the species A, in which segments will you see GFP if the construct contains all the regulatory regions sufficient to drive the Ubx expression?

b) In the species B, in which segments will you expect to see the GFP expression if the difference between the Ubx expression in two species is due to cis-regulatory changes?

c) In the species B, in which segments will you expect to see GFP if the difference between the Ubx expression in two species is due to changes in trans-regulatory factors?

Answer 1

Promoter is the regulatory DNA segment upstream to the gene to which it regulates. It has two part the core promoter and distal promoter.Core promoter contains TIS (transcription initiation site) and the TATA box 30 bp upstream to the TIS site where the per-initiation complex binds to initiate the transcription.In the distal region there is present of sequence specific DNA segment complementary to their target protein help in transcription of gene in various environmental condition or at developmental stages.

Now,

A )If the cis element from species A fused with GFP and developed the transgenic lines of species A then it will express in segment 5-10.

B) If the fusion construct is transformed in to the species B then it also expressed in the segment 5-10 in this species. Because the cis regulatory element for these segment is present.

C) If the regulatory elements are trans then there is no expression in the species B with this fusion construct because the cis element complementary to the trans factors are not present.