How do you consider DNA degradation? - (Jun/12/2007 )

Hello, I'm new in research and would like to ask a very basic question about DNA extraction.

I found that after extraction, if I got average amounts of DNA, running on a 1% gel against 1kb ladder, the gel pic looks nice and clean.
But if the DNA is very highly concentrated, although I got a very big band above 1kb, there will also be some smear down the lane. Do you consider this as degradation?

Did you do an RNAse treatment? If not, that smear can be the RNA... If you did it may be degradation I suppose.

Firstly, thanks a lot for everyone's comments!!


Well, I did add protease K which inactivates nucleases.....
But if that is degradation of RNA, why will it not turn up in lower concentrations of DNA?

Usually, I treat it with RNase A.

do you have a picture of your gel? Is your DNA genomic or plasmid?

I believe the RNA is merely a question of concentration. At low concentration, you can't see it. At higher concentration you do.

It was a genomic DNA.

Here is the picture of it...

In my opinion, definitely degradation. Add some RNAse to each to help (boil it first to eliminate any possible DNAse).

If you're just using the genomic DNA for PCR though, you're fine.


Amanda

from you picture i wanna say the sample of second lane is not dissolved properly in TE/water whatever you used