Over the past decade, RNA sequencing (RNA-seq) has become an indispensable tool for transcriptome-wide analysis of differential gene expression and differential splicing of mRNAs. However, as next-generation sequencing technologies have developed, so too has RNA-seq. Now, RNA-seq methods are available for studying many different aspects of RNA biology, including single-cell gene expression, translation (the translatome) and RNA structure (the structurome). Exciting new applications are being explored, such as spatial transcriptomics (spatialomics). Together with new long-read and direct RNA-seq technologies and better computational tools for data analysis, innovations in RNA-seq are contributing to a fuller understanding of RNA biology, from questions…
Haplotype phasing of genetic variants is important for interpretation of the maize genome, population genetic analysis, and functional genomic analysis of allelic activity. Accordingly, accurate methods for phasing full-length isoforms are essential for functional genomics study. In this study, we performed an isoform-level phasing study in maize, using two inbred lines and their reciprocal crosses, based on single-molecule full-length cDNA sequencing. To phase and analyze full-length transcripts between hybrids and parents, we developed a tool called IsoPhase. Using this tool, we validated the majority of SNPs called against matching short read data and identified cases of allele-specific, gene-level, and isoform-level…
Pepper is an important vegetable with great economic value and unique biological features. In the past few years, significant development has been made towards understanding the huge complex pepper genome; however, pepper functional genomics has not been well studied. To better understand the pepper gene structure and pepper gene regulation, we conducted full-length mRNA sequencing by PacBio sequencing and obtained 57862 high-quality full-length mRNA sequences derived from 18362 previously annotated and 5769 newly detected genes. New gene models were built that combined the full-length mRNA sequences and corrected approximately 500 fragmented gene models from previous annotations. Based on the full-length…
Motivation: Third-generation sequencing technologies can sequence long reads, which is advancing the frontiers of genomics research. However, their high error rates prohibit accurate and efficient downstream analysis. This difficulty has motivated the development of many long read error correction tools, which tackle this problem through sampling redundancy and/or leveraging accurate short reads of the same biological samples. Existing studies to asses these tools use simulated data sets, and are not sufficiently comprehensive in the range of software covered or diversity of evaluation measures used. Results: In this paper, we present a categorization and review of long read error correction methods,…
Newly emerged wheat blast disease is a serious threat to global wheat production. Wheat blast is caused by a distinct, exceptionally diverse lineage of the fungus causing rice blast disease. Through sequencing a recent field isolate, we report a reference genome that includes seven core chromosomes and mini-chromosome sequences that harbor effector genes normally found on ends of core chromosomes in other strains. No mini-chromosomes were observed in an early field strain, and at least two from another isolate each contain different effector genes and core chromosome end sequences. The mini-chromosome is enriched in transposons occurring most frequently at core…
Although messenger RNAs are key molecules for understanding life, until now, no method has existed to determine the full-length sequence of endogenous mRNAs including their poly(A) tails. Moreover, although non-A nucleotides can be incorporated in poly(A) tails, there also exists no method to accurately sequence them. Here, we present full-length poly(A) and mRNA sequencing (FLAM-seq), a rapid and simple method for high-quality sequencing of entire mRNAs. We report a complementary DNA library preparation method coupled to single-molecule sequencing to perform FLAM-seq. Using human cell lines, brain organoids and Caenorhabditis elegans we show that FLAM-seq delivers high-quality full-length mRNA sequences for…
The veined rapa whelk (Rapana venosa) is an important commercial gastropod in China but is also an important invasive pest worldwide. Lack of genome information restricts investigation of this species. Here we report the first full-length transcriptome database derived from six different developmental stages of the whelk obtained using the PacBio Iso-Seq. As a result, 88,162 high-quality and full-length unigenes were obtained with average length of 2895?bp, among which 70,496 unigenes were successfully annotated, and 192,951 CDS regions, 1182 transcription factors, 284,387 microsatellite loci, and 27,222 lncRNAs were indentified. This study provides a valuable resource for characterizing the R. venosa…
The stingless bee Melipona bicolor is the only bee in which true polygyny occurs. Its mitochondrial genome was first sequenced in 2008, but it was incomplete and no information about its transcription was known. We combined short and long reads of M. bicolor DNA with RNASeq data to obtain insights about mitochondrial evolution and gene expression in bees. The complete genome has 15,001?bp, including a control region of 255?bp that contains all conserved structures described in honeybees with the highest AT content reported so far for bees (98.1%), displaying a compact but functional region. Gene expression control is similar to…
The carbonic anhydrases (CAs) are a group of enzymes that play an important role in the absorption and transportation of CO2 in Saccharina japonica. They are encoded by a superfamily of genes with seven subtypes that are unrelated in sequence but share conserved function in catalyzing the reversible conversion of CO2 and HCO3-. Here we have characterized the CA members in the transcriptome of S. japonica using Single-molecule real-time (SMRT) sequencing technology. Approximately 9830.4 megabases from 5,028,003 quality subreads were generated, and they were assembled into 326,512 full-length non-chimeric (FLNC) reads, with an average flnc read length of 2181 bp.…
Long-read, single-molecule sequencing platforms hold great potential for isoform discovery and characterization of multi-exon transcripts. However, their high error rates are an obstacle to distinguishing novel transcript isoforms from sequencing artifacts. Therefore, we developed the package TranscriptClean to correct mismatches, microindels and noncanonical splice junctions in mapped transcripts using the reference genome while preserving known variants.Our method corrects nearly all mismatches and indels present in a publically available human PacBio Iso-seq dataset, and rescues 39% of noncanonical splice junctions.All Python and R scripts used in this paper are available at https://github.com/dewyman/TranscriptClean.
Comprehensive molecular characterization of myriad somatic alterations and aberrant gene expressions at personal level is key to precision cancer therapy, yet limited by current short-read sequencing technology, individualized catalog of complete genomic and transcriptomic features is thus far elusive. Here, we integrated second- and third-generation sequencing platforms to generate a multidimensional dataset on a patient affected by metastatic epithelial ovarian cancer. Whole-genome and hybrid transcriptome dissection captured global genetic and transcriptional variants at previously unparalleled resolution. Particularly, single-molecule mRNA sequencing identified a vast array of unannotated transcripts, novel long noncoding RNAs and gene chimeras, permitting accurate determination of transcription start,…
The Populus shoot undergoes primary growth (longitudinal growth) followed by secondary growth (radial growth), which produces biomass that is an important source of energy worldwide. We adopted joint PacBio Iso-Seq and RNA-seq analysis to identify differentially expressed transcripts along a developmental gradient from the shoot apex to the fifth internode of Populus Nanlin895. We obtained 87 150 full-length transcripts, including 2081 new isoforms and 62 058 new alternatively spliced isoforms, most of which were produced by intron retention, that were used to update the Populus annotation. Among these novel isoforms, there are 1187 long non-coding RNAs and 356 fusion genes.…
Scylla paramamosain is an important aquaculture crab, which has great economical and nutritional value. To the best of our knowledge, few full-length crab transcriptomes are available. In this study, a library composed of 12 different tissues including gill, hepatopancreas, muscle, cerebral ganglion, eyestalk, thoracic ganglia, intestine, heart, testis, ovary, sperm reservoir, and hemocyte was constructed and sequenced using Pacific Biosciences single-molecule real-time (SMRT) long-read sequencing technology. A total of 284803 full-length non-chimeric reads were obtained, from which 79005 high-quality unique transcripts were obtained after error correction and sequence clustering and redundant. Additionally, a total of 52544 transcripts were annotated against…
Alternative splicing performs a central role in expanding genomic coding capacity and proteomic diversity. However, programming of splicing patterns in engineered biological systems remains underused. Synthetic approaches thus far have predominantly focused on controlling expression of a single protein through alternative splicing. Here, we describe a modular and extensible platform for regulating four programmable exons that undergo a mutually exclusive alternative splicing event to generate multiple functionally-distinct proteins. We present an intron framework that enforces the mutual exclusivity of two internal exons and demonstrate a graded series of consensus sequence elements of varying strengths that set the ratio of two…
Normalization of cDNA is widely used to improve the coverage of rare transcripts in analysis of transcriptomes employing next-generation sequencing. Recently, long-read technology has been emerging as a powerful tool for sequencing and construction of transcriptomes, especially for complex genomes containing highly similar transcripts and transcript-spliced isoforms. Here, we analyzed the transcriptome of sugarcane, with a highly polyploidy plant genome, by PacBio isoform sequencing (Iso-Seq) of two different cDNA library preparations, with and without a normalization step. The results demonstrated that, while the two libraries included many of the same transcripts, many longer transcripts were removed and many new generally…