Project description:The ligation step in RNA sequencing library generation is a known source of bias. We present the first comparison of the standard duplex adaptor protocol supplied by Life Technologies for use on the Ion Torrent PGM with an alternate single adaptor approach involving CircLigase (CircLig). We also investigate whether using the thermostable ligase Methanobacterium thermoautotrophicum RNA ligase K97A (Mth K97A) for the initial ligation step in the CircLigase protocol reduces bias. A pool of small RNA fragments of known composition was converted into a sequencing library using one of three protocols and sequenced on an Ion Torrent PGM. The single adaptor CircLigase-based approach significantly reduces, but does not eliminate, bias in Ion Torrent data. Using Mth K97A as part of the CircLig method does not further reduce bias.
Project description:BackgroundNext-generation sequencing does not yield fully unbiased estimates for read abundance, which may impact on the conclusions that can be drawn from sequencing data. The ligation step in RNA sequencing library generation is a known source of bias, motivating developments in enzyme technology and library construction protocols. We present the first comparison of the standard duplex adaptor protocol supplied by Life Technologies for use on the Ion Torrent PGM with an alternate single adaptor approach involving CircLigase (CircLig protocol).A correlation between over-representation in sequenced libraries and degree of secondary structure has been reported previously, therefore we also investigated whether bias could be reduced by ligation with an enzyme that functions at a temperature not permissive for such structure.ResultsA pool of small RNA fragments of known composition was converted into a sequencing library using one of three protocols and sequenced on an Ion Torrent PGM. The CircLig protocol resulted in less over-representation of specific sequences than the standard protocol. Over-represented sequences are more likely to be predicted to have secondary structure and to co-fold with adaptor sequences. However, use of the thermostable ligase Methanobacterium thermoautotrophicum RNA ligase K97A (Mth K97A) was not sufficient to reduce bias.ConclusionsThe single adaptor CircLigase-based approach significantly reduces, but does not eliminate, bias in Ion Torrent data. Ligases that function at temperatures to remove the possible influence of secondary structure on library generation may be of value, although Mth K97A is not effective in this case.
Project description:We performed a parallel analysis of commonly used pre- and post-bisulfite WGBS library preparation protocols for their performance and quality of sequencing outputs. Our results show that bisulfite conversion per se generates pronounced sequencing biases, and subsequent fragmentation and amplification steps lead to several-fold overrepresentation of these artefacts. Standard pre-bisulfite library preparation methods lead to a significantly biased genomic sequence representation and a marked overestimation of methylation levels. We have integrated a bias diagnostic tool in the Bismark package and propose that amplification-free and post-bisulfite procedures should become the gold standard for WGBS library preparation.
Project description:gnp07_regeneome_microdissectionbias - microdissection vs no microdissection - Transcriptome bias induce by protocols used in microdissection - To compare RNA from flowers and RNA from microdissected flowers to know bias induce by microdissection (dissection from all tissues were collected to have a representation of entire flower)
Project description:gnp07_regeneome_microdissectionbias - microdissection vs no microdissection - Transcriptome bias induce by protocols used in microdissection - To compare RNA from flowers and RNA from microdissected flowers to know bias induce by microdissection (dissection from all tissues were collected to have a representation of entire flower) 2 dye-swap - treated vs untreated comparison
Project description:RNA-Seq technique was applied to investigate the effects of four cDNA amplification kits and two RNA-Seq library preparation kits to the deep sequencing results at different perspectives.
Project description:Genomic DNA extracted from IMR-90 cells were subjected to library preparations with tPBAT and sPBAT protocols. Sequencing was done with HiSeq X Ten platform and reads obtained were mapped with our own pipeline. The methylome data produced were compared. There is a little differences between the two datasets, which indicate sPBAT developped here is comparable with tPBAT protocol.
Project description:RNA-Seq technique was applied to investigate the effects of four cDNA amplification kits and two RNA-Seq library preparation kits to the deep sequencing results at different perspectives. The same set of semen samples were applied to investigate the qualitative and quantitative effect of four cDNA amplification methods and two RNA-Seq library preparation methods on sperm transcript profiling.