Hi everybody, I am struggling to understand my recent issue with a number of weak bands of various sizes in my NTC tubes. The reason why I struggle to understand this, is that I don't see anything like this in any of the samples e.g. negative samples are negative (clean, no extra bands), positive samples are positive (nice, clean one band without any extra bands) and the only weird looking lane is the NTC lane! If I had some contamination of my reagents, I would expect to see similar pattern in other tubes, not just NTC, right? I make a master mix for all the reactions, so the only difference between the NTC tube and other tubes is that there are some nucleic acids in other tubes (which may or may not contain the target sequence) and no template in the NTC tubes - same water, enzyme, primers, and reaction buffer. The mastermix is prepared in a dedicated room and the NTC tubes are closed there and not opened again until after the PCR to run a gel. I've never seen something like this before - any ideas of what might be going on? Some strange interactions between the primers that don't occur in the presence of other nucleic acids? Thanks a lot, Magda
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