"Unzipped" PCR band - (Nov/25/2010 )

Having little experience with PCR I'm at a bit of a loss. Can anyone advise what may cause this:





The PCR appears to have worked OK as the samples that didn't work (COT2 and COT5) were not expected to work.

neg is the negative control
lad is 100bp ladder

I have run this PCR product twice on gel and on both occasions the results have been the same.

Thanks in advance.

Now this I have never seen.

Might this be caused by the pipette tip stabbing into the gel?

Hmmm... a mystery indeed.

I did wonder whether pipette stabbing gel might have been the cause, but I would expect this to be localised to where the gel might be stabbed - not to all wells on both gels.

Fresh buffer and fresh agarose gel appears to have corrected the problem. So could have been either of these or some issue relating to the current which corrected itself overnight after an unplanned power cut to the site.