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suggestions on the genomic DNA quality - (Apr/02/2009 )

We have done genomic DNA isolation from tadpoles by phenol-chloroform method. A 0.5% Agarose gel was run. Genomic DNA appeared as a smear along with a thick band at the top. The concentration of DNA loaded was 1.5 ug. HindIII digest is loaded in first lane. We are planning to do restriction digestion of this DNA. Please suggest us if this DNA is of good quality and whether it is suitable for restriction digestion.We read that phenol, chloroform, and EDTA interferes with restriction digestion.Someone please suggest how to purify genomic DNA.
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I would say you have too much DNA there to check, we usually use 1ul of DNA to the gel (around 100 - 200 ng). In this picture it seems partially degraded, but that can be only from overloading.
There should be no smear in the lower part of gel.


You may also have some RNA, which would explain the lower smeared bands. This is innocuous except for misleading you in terms of the amount of DNA present, if that was important.