Northern Blot problem - problem with Northern blot (Sep/14/2006 )

Hi, my Northern blots were working ok but recently, i get a smear under every band and the signals are more reduced than before...I dont know what could be the reason, my RNA looks ok, can it be the probe? coz that's the only factor i changed, i used to have it by restriction digestion from a plasmid that has this cDNA and now i get if from PCR from another plasmid?
Any suggestions for the reasons for that would be greatlly appreciated
thanks a lot for your help

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Do you purificate your PCR product and how? It might be that you also get little fragments with the pcr that also act as an probe.

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Thanks a lot for your reply, yes I purified my PCR product by running it on agarose gel and purifying from th egel using Qiagen Kit

thanks a lot

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