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anna_m 09-10-2013 06:54 AM

Extra peak after TruSeq DNA library prep
1 Attachment(s)
We made library preps following the standard TruSeq DNA library prep method, beginning with 3ug gDNA and took this through the steps shearing-end repair-A tailing-ligation-size selection-PCR.

We use the blue pippin for size selection and 6 cycles of amplification.

Now, we are seeing an extra peak over double the size of the intended library peak (see attached). Is this a primer-dimer peak? Or a single-stranded artefact? Do you think it will affect the sequencing of the library?

Any advice you could give me would be much appreciated.

Thank you.

microgirl123 09-10-2013 10:36 AM

It's not primer dimer (that would be ~128 bp). It may just be a bubble peak from too many cycles of PCR. Sometimes, when the strands reanneal only the adapters anneal with a mismatched fragment in the middle. This creates a "bubble" and the DNA runs strangely on the BioAnalyzer.

Genohub 09-12-2013 07:16 AM

Typically bubble products won't affect your sequencing results because the double stranded product is denatured prior to cluster generation. To verify, heat a small aliquot of the sample to 95C for 5 minutes and place on ice. The denatured product should appear as a single band on a Bioanalyzer RNA Pico 6000 Chip Kit.

- Genohub

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