In mice engineered to overexpress the syndecan-1 gene in the hypothalamic region of the brain and other tissues, normal control of feeding by antisatiety peptides is disrupted, and the animals overeat and become obese. Other studies have shown that syndecan-3 may also be involved in the regulation of feeding behavior. Given the following information, which of these outcomes might you expect in experimentally manipulated mice?

I. Hypothalmic expression of syndecan-3 is increased by fasting.

II. Syndecan-3 knockout mice are resistant to diet-induced obesity.

III. Heparinase can cleave syndecan-3 to release heparin sulfate GAG chains that may suppress the activity of antisatiety peptides and feeding behavior.

Following statements are:

A. Overexpression of heparinase in mice with normal levels of syndecan-3 would result in resistance to diet-induced obesity.

B.  In mice with normal levels of syndecan-3, fasting followed by free access to a high-fat diet would lead to resistance to diet-induced obesity.

C. Lack of heparinase in mice with normal levels of syndecan-3 would result in animals that overeat and become obese.

D. Overexpression of heparinase in syndecan-3 knockout mice would reverse the resistance to diet-induced obesity.

Which of the following combination is correct?

#Question id: 4065

#Unit 3. Fundamental Processes

The NtrC protein from E. coli

a. is a σ54 RNA polymerase.  b. stimulates transcription of the glnA gene.

c. is activated by a protein kinase called NtrB.

d. binds both to an enhancer site upstream of the glnA gene and to RNA polymerase.

e. has ATPase activity.

#Question id: 4066

#Unit 3. Fundamental Processes

Specific DNA control elements in promoters can

a. interact with general transcription factors.

b. interact with repressor proteins. 

c. interact with activator proteins.

d. remain unavailable because of condensed chromatin.

#Question id: 4067

#Unit 3. Fundamental Processes

Reporter genes are used to

a. express enzymes that are not easily assayed in cell extracts.

b. express enzymes that are easily assayed in cell extracts.

c. characterize DNA control elements. 

d. characterize reporter plasmids.

#Question id: 4068

#Unit 3. Fundamental Processes

The three eukaryotic RNA polymerases can be distinguished by

a. the types of genes they transcribe.

b. the number and types of large subunits.

c. their differential sensitivities to cycloheximide.

d. their differential sensitivities to α-amanitin.

#Question id: 4069

#Unit 3. Fundamental Processes

Which of the following can be identified using a series of promoter linker scanning mutations?

a. areas of the promoter that are non-essential

b. areas of the promoter that are essential

c. the presence of separate transcriptional control regions

d. spacing constraints on separate transcriptional control regions

#Question id: 4070

#Unit 3. Fundamental Processes

An enhancer

a. can be located upstream of a promoter.

b. can be located downstream of a promoter.

c. can be located a variable distance from the promoter.

d. is always located within 1 kb of the promoter.

e. can be cell-type-specific.