Gene regulation - ME1 promoter and upstream region

Hi,

I've got this question and I'm not so sure about the answer. It is taken from Genetic Analysis: An Integrated Approach, chapter 15:


A muscle enzyme called ME1 is produced by transcription and translation of the ME1 gene in several muscles during mouse development, including heart muscle, in a highly regulated manner. Production of ME1 appears to be turned on and turned off at different times during development. To test the possible role of enhancers and silencers in ME1 transcription, a biologist creates a recombinant genetic system that fuses the ME1 promoter, along with DNA that is upstream of the promoter, to the bacterial lacZ(B-galactosidase) gene. The lacZ gene is chosen for the ease and simplicity of assaying production of the encoded enzyme. The diagram shows the structure of the recombinant, as well as bars that indicate the extent of six deletions the biologist makes to the ME1 promoter and upstream sequences. The table displays the percentage of B-galactosidase activity in each deletion mutant in comparison to the recombinant gene system without any deletions.

Note that the bars in the diagram show the portions of the upstream region that are NOT present in each recombinant.

 
1. Does this information indicate the presence of enhancer and/or silencer sequences in the ME1 upstream sequence?

2. Give a moleculare explanation for the fact that the expression of ME1 gene is activated and silenced in different times during the normal development of mice.

3.why does sequence d deactivate lacZ gene transcription?

Any help would be very much appreciated!

Thanks

 


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