Peter, it neraly looks like a ladder, so a number of bands with different sizes ranging in size from about 100 bp to more than 1000 bp - all very weak, but they are there. I am going to try to use a lower concentration of primers (go down from 0.5 uM final concentration to 0.1 uM) and rise the annealing temperature, so hopefully I'll get rid of those. Still, would be nice to know what's going on...Magda
P.S. Sorry for not defining the abbreviation - NTC = no template control. ________________________________________ From: methods-boun...@oat.bio.indiana.edu [methods-boun...@oat.bio.indiana.edu] On Behalf Of Peter Ellis [pj...@cam.ac.uk] Sent: Saturday, September 18, 2010 6:43 AM To: meth...@magpie.bio.indiana.edu Subject: Re: non-specific bands in NTC On 17/09/2010 15:09, Nick Theodorakis wrote: > On Sep 17, 7:59 am, WS<novalidaddr...@nurfuerspam.de> wrote: >> NTC tubes? WTH is that? Neg Temp Coeff? >> >> /Wo > > I would have guessed "no template control" except that I'm not sure > how that would be different than her negative samples which she says > are clean. Depends what you're testing for - a "negative" sample could be a template which won't amplify. e.g. genotyping for the presence/absence of a transgene. Positive would be DNA from a known transgenic animal, negative would be DNA from a known wildtype animal, no template control would have no template. In that case the negative control would be controlling for the specificity of the PCR in detecting the tg against genomic background, while the no template control would be testing for contamination in one or more of the reagents. Magda: What size are the erroneous products? Some sort of primer dimer is certainly a possibility. Peter _______________________________________________ Methods mailing list Methods@net.bio.net http://www.bio.net/biomail/listinfo/methods _______________________________________________ Methods mailing list Methods@net.bio.net http://www.bio.net/biomail/listinfo/methods
