PCR contamination mystery - (Jun/01/2005 )

hello

i got strong smear in my agarose gel photo sometimes, but sometimes, this does not happen. i used all new reagents (dNTP, primers, taq polymerase, MgCl2, autoclaved water, pcr buffer) and arts tips and changed my lab coat. this time, all the pcr reactions got strong smear. however, the negative control didnt have any smear. I don't think the templates (totally 6 different templates) had been contamined. has anyone come across this problem?? thanks
samantha

Hi,

to me it sounds more like unspecific amplification of genomic DNA than contamination.
I would change reaction conditions, less MgCl2, higher annealing temperature,
less template DNA.

Regards,
hennry

I agree, sounds like unspecific amplification.

Good guidelines how to change your reaction can be found here:

http://info.med.yale.edu/genetics/ward/tavi/Trblesht.html