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Old 12-10-2010, 08:23 AM   #1
cmawhinney
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Location: Boston, MA

Join Date: Oct 2009
Posts: 15
Default ChIPseq: Strange Peaks after Gel Extraction

x-posted from general: i didn't realize i posted in the wrong forum until today.

Hi,

I've been doing ChIP library preps for a good while now and never before have I seen anything like this and was hoping someone maybe has?

I am seeing two peaks in my samples. One at around 200bp and one at around 278 for my single read samples and one around 228 and one around 300 for my paired end samples. It doesn't makes any sense to me since I normally take my gel slices around 250bp. It also doesn't make any sense as to why there are two separate peaks.

These samples were gel extracted, cleaned up on a qiagen column and then PCR amplified and cleaned up with SPRI beads.

The ONLY thing I did differently this time was play around with the adapter concentrations. Meaning if anything I added less adapter then I usually do. I ran 6 samples (4 SR and 2 PE) and some on different gels. All of my samples had these double peaks.

Please see the attached pictures from the bioanalyzer run. (please see this thread for the photos: http://seqanswers.com/forums/showthread.php?t=8325

Any input is GREATLY appreciated.

Chris.
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