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Genomic DNA - (Mar/18/2010 )

Hi all,

I have recently isolated a huge amount of genomic DNA from mouse tail samples by phenol/chloroform extraction. When I run the undigested DNA on the gel I could not find any discrete bands above 10000bp, but I could find a large amount of DNA in the gel pocket. I repeated the electrophoresis twice and still found the same result. For your information I am using 0.7% agarose gel. Please help me out as I have to use this genomic DNA for southern blot.



Why would you expect to see discrete bands for DNA? Usually you just see a big bright blob in or around the well (complexed DNA) and a smear below that.


could we see a picture of this band?

a blob that fails to move out of the well may indicate that your DNA sample is heavily contaminated and needs to be cleaned up more.

you could try cutting a sample of your gDNA with EcoRI and a second sample with NotI.Your blob of DNA should enter the gel, producing a smear in the kb range. IF the DNA does not cut, the sample is heavily contaminated.