PolyA enrichment library preparation positively selects for transcripts with polyadenylated tails and is often referred to as mRNA sequencing. All mRNA and noncoding transcripts with polyA tails are captured via hybridization to polyT oligos on magnetic beads, leaving untailed molecules behind. RNA integrity is of particular importance with this method as degradation of the polyA tail will result in reduced mRNA capture and may affect downstream analysis. As only polyA tailed transcripts will be included in the final dataset, this is the first choice for many eukaryotic studies looking for changes in coding regions.
For this pipeline, SeqCenter uses the Illumina Stranded mRNA Prep kit to generate unbiased RNA libraries. mRNA enrichment is a more cost-effective method and generates greater exonic coverage; however, the major limitation is that it can only be used for organisms with polyA tails. It also requires high-quality RNA and higher minimum sample concentrations.
We strongly recommend visiting our overall Illumina RNA services page for additional considerations when planning any RNA experiment, and we encourage all customers to check out the tips for handling RNA and guidance when assessing sample quality for submission.