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Old 03-16-2018, 10:32 AM   #1
pennypeverell
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Location: Spain

Join Date: Mar 2018
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Unhappy ATACseq - large nucleosome peaks

Hello everyone!

I am new to ATAC seq and I'm having problems with my libraries. I'd very very thankful if anyone of you is willing to help.

From the bioanalyzer profile I se the 180 bp peak and it should be the mono-nucleosome peak. And that's ok.

The problem is I see other larger peaks (possibly the multiple nucleosomes?) but they have higher intensity than the 180 bp peaks!

I'm a completely noob, but I've been told this is a problem. That larger nucleosomes peaks should be present, but with less intensity compared to the 180 bp peaks. Do you suggest me to sequence these library or throw them away and trying again? Maybe trying to improve my tagmentation step?

I read some similar thread in the forum but nobody is actually having my same bioanalyzer profile (or at least I didn't found it).

I'm attaching some pics of the byoanalizer profiles so maybe you could better figure it out what I am talking about.

Please, any opinion/advice/suggestion would be a great help!

Thanks

Penny






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Last edited by pennypeverell; 03-16-2018 at 10:38 AM.
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Old Today, 12:54 AM   #2
Grg91
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Default same profile

Hi! Did you solve this?
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Old Today, 08:34 AM   #3
atpoint
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Location: Muenster

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The two bioanalyzer pictures from OP actually look OK to me, clear nucleosomal periodicity. Note that the peak at 180bp is not the mono-nucleosomal but the nucleosome-free peak. From the 180bp, you have to subtract about 100bp for adapter content, leaving you with 80bp inserts which is from nucleosome-free DNA. Fragments of about 200bp are mono-nucleosomal ones.

@Grg91 Can you post a picture of your libraries, so that we can have a look.
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