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LacZ PCR genotyping -ve control contamination


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#1 Dave_Kub_11

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Posted 13 February 2010 - 10:03 AM

Hello everyone. I am new to this forum and wonder if someone could help me with a rather annoying problem as I have tried to troubleshoot it the best I can!!

I have been getting a band popping up in my negative controls in my genotyping for the lacZ transgene. The contaminant band is the same size as that of the LacZ (~315bp)

I used fresh PCR reagents, fresh dilutions of primers, water, pipette tips etc. and I am still getting this contamination. I have done this several times now.

I have ordered new primers as I suspect the contamination might be there.

If anyone has any experience of having this problem, particularly with lacZ (which I am told is rather susceptible to contamination) I will be much appreciated if you could help me out!!!

#2 bob1

    Hmmm, I think it's working

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Posted 14 February 2010 - 03:30 PM

You are working off a plasmid that has probably been extracted thousands of times in the lab you are working in, I'm not surprised you have contamination issues, the air will be full of it.

I suggest trying setting your PCR up in another room if possible; somewhere where no plasmids are extracted/bugs grown. If that isn't possible, try keeping a set of pipettes just for setting up PCR, and have a PCR region, where you only set up PCRs.

#3 Dave_Kub_11

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Posted 15 February 2010 - 10:36 AM

View Postbob1, on Feb 14 2010, 03:30 PM, said:

You are working off a plasmid that has probably been extracted thousands of times in the lab you are working in, I'm not surprised you have contamination issues, the air will be full of it.

I suggest trying setting your PCR up in another room if possible; somewhere where no plasmids are extracted/bugs grown. If that isn't possible, try keeping a set of pipettes just for setting up PCR, and have a PCR region, where you only set up PCRs.



I set up PCR in another room as you suggested and I am still getting this contamination occurring. I even cleaned my PCR workstation quite thoroughly and it didn't make any difference. I used fresh primers that arrived today and I still got the contamination.

I wonder if DMSO might be causing this (although I have used two different bottles to check if that is the cause of the contamination, no luck)

#4 lab rat

    Why does a science forum not have pictures of mice and rats?

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Posted 15 February 2010 - 09:23 PM

Maybe your pipettes are contaminated. Are you using barrier tips?
42..."An immutable fixed-precision number of unlimited magnitude." <a href="http://en.wikipedia.org/wiki/Python_(programming_language)" target="_blank">http://en.wikipedia.org/wiki/Python_(programming_language)</a>, accessed 25June2009.





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