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  • Ion Plus Fragment Library Prep Efficiency

    I've had some experience with both Illumina library preps and Ion Torrent library preps and I am thinking about efficiencies on a basic molecular level. Ion Torrent/454 preps use blunt end ligation of 2 different adapters, while Illumina uses TA-ligation of 1 adapter. Correct the following logic if I'm wrong, if we have 4 dsDNA molecules:

    Illumina's protocol should arrive at 8 effective ssDNA molecules, for 100% efficiency. The Y-adapter prevents misdirectional adapter ligation, but allows adapter-adapter ligation dimers to still form.

    Ion Torrent's protocol should arrive at 2 effective dsDNA molecules, for 50% efficiency, as 25% of the fragments will have A-fragment-A and 25% will have P1-fragment-P1. Granted, these will be non-amplifiable but they do sequester true DNA fragments in solution. Additionally, the blunt-end ligation protocol would hypothetically also cause a whole mess of chimeric ligation products, such as A-fragment-fragment-P1. Fragments shouldn't ligate on both sides of an adapter due to the double T tailing, which also prevents misdirectional adapter ligation. Adapter ligation dimers will still form, at much the same rate as Illumina adapters (?), though composed of 3 combinations of the 2 adapters.

    Any issues with this? Why didn't Life Tech go down the TA route as that would solve a lot of the blunt-end problems? And yes, I am aware that there are some groups that have developed their own Y adapters for use on the Ion Torrent/454.

    Looking forward to comments and/or kind remarks that someone else has already talked about this

  • #2
    Just an FYI...454 also uses Y adaptors similar to Illumina. This has been the case for the past few years since the release of their Rapid Library prep kits.

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    • #3
      Thanks RCJK. I had forgotten that about the 454 quick prep changes.

      And thank you genseq for the images. I had seen one of those before, which prompted my initial post. I do recognize that the adapters *shouldn't* form self ligating dimers, for the reasons you state, but they do in some preps so it's interesting why.... I would think the Y adapters form them much less readily, but I guess it comes down to the thermodynamics of the reaction.

      Regardless, it does seem like Y adapter-based chemistry is more efficient.

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      • #4
        sticky adapters are more efficient. I don't think anyone debates that. Blunt end ligation is just a little faster and cheaper as it doesn't require tailing. You can make libraries from pg of material with blunt end ligation, so I'm not sure if the efficiency is really an issue. Blunt is theoretically 50% less efficient if you assume perfect tailing and ligation for sticky adapters. That's probably a cycle or so change in amplification.

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        • #5
          Has anybody experience to create Y adapters for sequencing with IT?

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          • #6
            design our own P1/A ion torrent adapters

            Originally posted by Vaida View Post
            Has anybody experience to create Y adapters for sequencing with IT?
            did anybody have any experience with the disign of Y-adapter sequeces for Iontorrrent? besides. I was wondering if it's possible to redesign my own IT P1/A1 adapter sequence based on the initial iontorrent A/P1 adapter sequences. since I want to perfrom multiplexing sequence on 318 chip, the barcode sequences kit provide by lifetech is too expensive to be offordable.
            best regards

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            • #7
              I am new to sequencing world. We are trying to perform library preparation for exome sequencing using Ion Proton. During the process tehre is three days hybridization step which got interrupted due to some power failure overnight.

              We are in dilemma that should we continue with hybridization step or should be abort and start again with the new sample.

              Has anyone had this issue before?

              Can you suggest , whats the best possibility?

              Thanks in advance for all your suggestions.

              Regards

              vandy

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              • #8
                Why didn't Life Tech go down the TA route as that would solve a lot of the blunt-end problems?

                The reason is Illumina owns the IP for that form of library prep.

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                • #9
                  Originally posted by JackQuist View Post
                  Why didn't Life Tech go down the TA route as that would solve a lot of the blunt-end problems?

                  The reason is Illumina owns the IP for that form of library prep.
                  They do not own an IP for tA libraries.

                  Comment


                  • #10
                    can you re-send this article?

                    Comment


                    • #11
                      This is the design of BioDynami NGS DNA Library Prep Kit (Ion Torrent Platform): the insert concatemer ligation (due to blunt end ligation) is eliminated with our unique technology.



                      more details at https://biodynami.com/product/ngs-dn...-prep-kit-ion/

                      Comment

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