Commonly associated with reduction of transcription the...

Commonly associated with the reduction of transcription, the following data (10 points) on DNA methylation come from a study of the impact of the location and extent of DNA methylation on gene activity in human cells. A bacterial gene, luciferase, was cloned next to eukaryotic promoter fragments that were methylated to various degrees in vitro. The chimeric plasmids were then introduced into tissue culture cells, and the luciferase activity was assayed. These data compare the degree of expression of luciferase with differences in the location of DNA methylation (Irvine et al, 2002. Mol and Cell Biol. 22= 6689-6696). What general conclusions can be drawn from these data? Patch Size of Number Relative Methylation Methylated Sequences (kb) CpGs Expression 0.0 490X DNA Segment outside transcription unit (0-7.6 kb away) 2.0 100 102 593 290X 250X 12.1 0.0 Inside transcription unit 490X 80X 108 134 593 2.4 12.1

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00:01 Hello students, in this question reading said that dna methylation is commonly associated with reduction of transcription and the question says that the following data which is represented here come from a study of the impact of a location and extent of dna methylation.

00:38 So this data shows impact of a location and extent of dna methylation on gene activity in human cells and for this a bacterial gene which is known as luciferase was cloned next to eukaryotic promoter fragments were methylated to various degrees in vitro and the chimeric plasmids were then introduced into the tissue culture cells and the luciferase activity was assay and these data compare the degree of expression of luciferase with differences in the location of the dna methylation and the extent of dna methylation.

02:09 Now on the basis of this we have been asked what conclusions can you can be drawn from this data.

02:21 Now we must know that this data shows the impact of location and extent of dna methylation on gene activity which we can assess by the expression of the luciferase enzyme.

02:40 Here it shows the location location this one shows the location and this column shows the extent of dna methylation this column shows the activity of luciferase activity.

02:59 Now here we are comparing the first two things outside of the transcription and inside of the transcription which means that this data from here to here it shows the methylation outside of the actual gene and this data shows the methylation which is within the gene or inside the transcription unit.

03:30 So as we can see that here if we compare those outside and inside the overall when the methylation is inside transcription unit the first conclusion will be when the methylation is inside transcriptional unit or inside the gene the reduction in transcription is more transcription reduction is more.

04:13 How we can compare the luciferase activity here on this side more luciferase activity means there is less reduction in transcription if there is more transcription then there will be more luciferase expression.

04:32 So as we can see comparatively we can see 490, 490, 290, 80, 5 and 2, 250...

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