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MSP trouble - (Feb/23/2006 )

I got both 'U' and 'M' bands with my MSP primers, but I am pretty sure that the control DNA was not methylated. I put the 'C'/'T' alternatives on the 3' end of the primers for 'M'/'U' amplifications. Did anybody have the same problem? Do you think the amplification will be more specific if I incease the melting tempratue?(I use 55C) . By the way, which kind of enzyme do you usually use for MSP? I use Qiagen hotstar Taq (35 cycles). Is there any enzyme better than this one? Many thanks.

-Haiyan-

Sorry, I mean the annealing Tm (not the melting Tm). If higher annealing Tm will give more specific product? Thanks.

-Haiyan-

sure can!!

but have you ruled out that you have a mixed population of cells? which will give you the bands you see.

Nick

-methylnick-

QUOTE (methylnick @ Feb 24 2006, 11:49 AM)
sure can!!

but have you ruled out that you have a mixed population of cells? which will give you the bands you see.

Nick


I have the same promblem with Haiyan, I got both 'U' and 'M' bands with the positive control DNA ,which should not have the U band as other literatures have said,but the negative control have only one U band.I think i have no rcontamination when extracting the gDNA.
Do you think that primers designed from the Methprimer is specific?

I do the nested PCR.The first round is 40 cycles,and the second round is40 cycles,too.

Could someone help me ,please?Thank you very much!!

-MSPnewer-

two rounds of 40 cycles is way too much for MSP. any background signal will come up as a false positive otherwise.

Try reducing the number of cycles to say 30, 25 or even 20 cycles. 40 cycles will saturate the PCR.

Nick

-methylnick-