Southern blotting

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eTiT
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Southern blotting

Post by eTiT » Tue Aug 16, 2005 2:04 pm

Here's a question that i have encountred. A radioactive-labelled DNA probe containing the nucleotide sequence of a gene has been prepared. DNA collected from a cell thought to contain the gene, then underwent the Southern blotting procedure. One of the fragments of DNA is shown to be capable of hybridizing with the radioactive-labelled DNA probe. RNA, collected from the same source, is subjected to the Northern Blotting procedure. The same radioactive-labelled DNA probe is use. In this case, the proble did not hybridize with any RNA fraction. Why is this so? Could it be due to experimental errors?

Hope someone can clear my doubts. Thanks!

sdekivit
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Post by sdekivit » Tue Aug 16, 2005 4:48 pm

did u get RNA from the DNA you used for the analysis ? OItherwise the fractioning of the RNA results in other fragments that are not capable of hybridizing with the probe.

eTiT
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Post by eTiT » Wed Aug 17, 2005 2:15 am

Yah. I obtained the RNA from the same source.

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Post by DevGrp » Mon Aug 22, 2005 8:59 am

Is this because the gene isn't being expressed?


All cells with nucleii wiil contain the DNA of the gene but the RNA will be present only if that gene is being transcribed (expressed)

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Post by Jelanen » Tue Aug 23, 2005 10:15 pm

What type of cell are we talking about? What kind of RNA? If we're talking eukaryotic cells, then the answer might simply be that the RNA in the Northern blot was mRNA and had introns excised, therefore making it different in sequence than the DNA from whence it was transcribed. Though that explanation still depends on what RNA type we are talking about...

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Sam
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Whats northan blotting?

Post by Sam » Sat Sep 10, 2005 12:30 am

I have heared of southern blotting for school but whats northern. eg how is it done, what is required?
:p

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canalon
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Re: Whats northan blotting?

Post by canalon » Sat Sep 10, 2005 2:02 am

Sam wrote:I have heared of southern blotting for school but whats northern. eg how is it done, what is required?


Basically the same thing as a southern, but you use RNA instead of DNA.
And a western blot is the same but with protein (and Antibodies instead of a DNA probe).
As a side note, Southern is the name of the scientist who invented the technique of the DNA/DNA blotting, but Northern and western were named like this just for the joke... :roll:

PAtrick

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Post by Sam » Sat Sep 10, 2005 10:30 pm

Thanks PAtrick
:p

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