The full-length transcriptome of C. elegans using direct RNA sequencing

  1. John K. Kim1
  1. 1Department of Biology, Johns Hopkins University, Baltimore, Maryland 21218, USA;
  2. 2Department of Biomedical Engineering, Department of Molecular Biology and Genetics, Johns Hopkins University, Baltimore, Maryland 21218, USA;
  3. 3Department of Computer Science, Johns Hopkins University, Baltimore, Maryland 21218, USA
  • Corresponding authors: wtimp{at}jhu.edu, james{at}taylorlab.org, jnkim{at}jhu.edu
  • Abstract

    Current transcriptome annotations have largely relied on short read lengths intrinsic to the most widely used high-throughput cDNA sequencing technologies. For example, in the annotation of the Caenorhabditis elegans transcriptome, more than half of the transcript isoforms lack full-length support and instead rely on inference from short reads that do not span the full length of the isoform. We applied nanopore-based direct RNA sequencing to characterize the developmental polyadenylated transcriptome of C. elegans. Taking advantage of long reads spanning the full length of mRNA transcripts, we provide support for 23,865 splice isoforms across 14,611 genes, without the need for computational reconstruction of gene models. Of the isoforms identified, 3452 are novel splice isoforms not present in the WormBase WS265 annotation. Furthermore, we identified 16,342 isoforms in the 3′ untranslated region (3′ UTR), 2640 of which are novel and do not fall within 10 bp of existing 3′-UTR data sets and annotations. Combining 3′ UTRs and splice isoforms, we identified 28,858 full-length transcript isoforms. We also determined that poly(A) tail lengths of transcripts vary across development, as do the strengths of previously reported correlations between poly(A) tail length and expression level, and poly(A) tail length and 3′-UTR length. Finally, we have formatted this data as a publicly accessible track hub, enabling researchers to explore this data set easily in a genome browser.

    Footnotes

    • [Supplemental material is available for this article.]

    • Article published online before print. Article, supplemental material, and publication date are at http://www.genome.org/cgi/doi/10.1101/gr.251314.119.

    • Freely available online through the Genome Research Open Access option.

    • Received April 15, 2019.
    • Accepted January 6, 2020.

    This article, published in Genome Research, is available under a Creative Commons License (Attribution 4.0 International), as described at http://creativecommons.org/licenses/by/4.0/.

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