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  • nboom
    Junior Member
    • Oct 2019
    • 1
    #1

    high rRNA after poly(A) selection

    Hi,

    About half our samples post library prep (poly(A) selection) + sequencing had around 50% rRNA content. The samples were re-prepped in the facility but the rRNA contents were similar a second time.

    The facility now argue that the rRNA "contamination" is sample related and not due to failed library prep. Since the poly(A) selection enriches for all RNAs that have a poly(A) tail, mostly mRNAs, rRNA removal should have been effective? What can have gone wrong?

    The tissue is skin and we used mirVana kit to extract RNA (perhaps not optimal - could the inclusion of small RNAs caused an issue in the library prep?). All our samples had RIN of 8 and above.

    Thanks in advance!
    Tags: library preparation, poly a, rna sequencing, rrna contamination
  • Michael.Ante
    Senior Member
    • Oct 2011
    • 127
    #2
    Hi,

    What library prep have you used?
    Do you differentiate between MT-rRNA and nucleic rRNA? The mitochondrial rRNA molecules have a polyA tail and are therefore detectable after polyA selection.

    Cheers,

    Michael

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