Question

During an experiment investigating the ability of different chemical compounds to influence DNA methylation levels in mice, one cage of pregnant mice are fed a control compound which does not influence DNA methylation, a second cage of pregnant mice are fed 5-Azocytidine, which is a known inhibitor of DNA methylation, and a third cage of pregnant mice are fed a third chemical with an unknown effect on methylation. All of the mouse pups (babies) are Avy/a. Unfortunately, the pups all escape from their cages and you lose track of which pups came from which cage. However, you notice that there are three phenotypic classes of mouse pups: yellow, slightly mottled, and pseudo-agouti, and there are roughly equal numbers of pups in each phenotypic class. Assuming that all of the pups from each phenotypic class escaped from one of the three cages, which phenotype matches with which cage?

Group of answer choices

Cage 1:

      [ Choose ]            Yellow            Pseudo-agouti            Slightly mottled      

Cage2:

      [ Choose ]            Yellow            Pseudo-agouti            Slightly mottled      

Cage3:

      [ Choose ]            Yellow            Pseudo-agouti            Slightly mottled      

Answer 1

Methylation involves addition of methyl groups on CG islands present on the promoter. This modification cause silencing of the gene. If we use DNA methylated inhibitor, this inhibits DNA methylase enzyme this interfere in the methylation and causing re expression of the gene .

Here mice were kept in 3 cages

Cage 1 mice fed with control compound, which do not affect methylation.

Cage 2 , 5 aza cytidine, DNA methylase inhibitor

Cage 3, fed with chemical which has unknown effects on methylation.

So among the pupa which has restored the colour of the coast must be belong to cage 2, as they are treated with azacytidine. Which restored expression of the gene and restored colour I the mice .

Yellow color mice - cage 2 ,treated with azacytidine

Slightly molted mixed colour ( yellow and agouti) must be from cage 3, chemical with unknown effect on methylation

Pseudo agouti - cage 1 , control group no change in colo6.