How PCR product becomes gelly? - (Jun/01/2007 )

My friend is developing PCR assay for Brucella is seeking answer why he is getting jelly PCR product. I could not believe first day he told me about it but he showed me three products from different PCR. We could not pipette out the PCR product and run electrophoresis because it is Gel. This may appear in one or two of the PCR tubes in single reaction. We have it also in template negative control.

We are wondering how the normal PCR reagents and DNA ends up with gelly substance?

any idea?

I suspect that whats happening is the tubes or plate isn't quite sealed properly, and the water has started evaporating. This happened to me when I left my PCR products in a 96 well plate for a few days, but the plastic seal wasn't stuck down propertly. I just added some more nuclease free water to reconstitute the product, then ran my products on a gel again to check they were still ok (of the 6 products I had, only 1 couldn't be saved).