rRNA Depletion Kits Research Articles

First report of cucumber green mottle mosaic virus infecting Cynanchum rostellatum in China.

Cucumber green mottle mosaic virus (CGMMV) was first discovered on cucumber in the United Kingdom in 1935 (Ainsworth, 1935), and has spread worldwide except to Antarctica (Jones, 2021). Given its extensive damage, it is considered an important pathogen on global cucurbit plants and fruit crops. In China, CGMMV was first reported on pumpkin in Guangxi Province in 2003 (Qin et al., 2005), and occurred on 34 plants species across 23 provinces (Liu et al., 2016). Cynanchum rostellatum is a member of the family Apocynaceae. In July 2021, leaves of C. rostellatum exhibiting virus-like symptoms (yellowing, severe crinkling, deformation) were observed and collected in Liaoning Province, China. Aphids were also observed on the leaves and stems (Fig. S1) of the plants and were collected. Total RNA was extracted from diseased leaves following the CTAB method, followed by the depletion of ribosomal RNAs (rRNA) with TIANSeq rRNA Depletion Kit (Tiangen, China). The RNAs were, then processed into a DNBSEQ LncRNA-Seq library, and sequenced on the MGISEQ-2000 platform at BGI Genomics (Wuhan, China). A total of 106.98 M clean reads were obtained after data filtering using SOAPnuke software (BGI, China). The clean reads were assembled into contigs using CLC Genomics Workbench 11 (Qiagen, USA) and Trinity v2.0.6 (Haas et al., 2013). A contig (4,760 reads, average coverage:73.76) of 6,391 nucleotides was found to share the highest sequence identity (99.83%) with CGMMV isolate GDLZ (MK933286), irrespective of other virus-like contigs related to Polerovirus and Totivirus. Based on the genome of GDLZ isolate, seven specific primers (Table S1) were designed to amplify the full viral genomic sequences using a PrimeScriptTM One-Step RT-PCR Kit. Seven expected amplicons were obtained, cloned, and sequenced. The complete genome was determined to be 6,423 nucleotides (GenBank accession number OR854819) in length and designated as LNMJ isolate. LNMJ shared 96.8%-99.7% nucleotide sequence identities with CGMMV isolates from China. Phylogenetic analysis based on the complete genome sequences showed that LNMJ clustered together with CGMMV isolates hn (GenBank accession number KC851866), GDLZ (GenBank accession number MK933286), and JD8 (GenBank accession number KM873784) from China. The specific primers LM-TJ-3F/3R were designed to determine the virus-symptom association for LNMJ, and all twelve symptomatic C. rostellatum plants collected from fields tested positive for LNMJ. Two out of six randomly selected aphids from the diseased plants also tested positive. To further prove its infectivity, LNMJ was inoculated mechanically onto ten healthy Nicotiana benthamiana plants, and the results indicated a high infection rate of 80% (8/10), at 30 days post-inoculation despite no distinct symptoms observed. To our knowledge, this is the first report of the natural infection of C. rostellatum plants with CGMMV. C. rostellatum is a widespread herb in China (Wei et al., 2019) and more surveys are needed to determine the distribution of CGMMV. The habitats of C. rostellatum span diverse agroecological zones, and thus our study underscores the potential spillover of CGMMV to neighboring crops as a significant risk.

First Report of Youcai Mosaic Virus Infecting Yam in China.

Yam (Dioscorea opposita Thunb.) is cultivated mainly as a functional food and for nutritional and medicinal purposes in China (1). It is propagated through tubers and this facilitates the spread and accumulation of viruses in the crop, eventually leading to yield losses (2). At present, different virus species belonging to the genera Aureusvirus, Badnavirus, Carlavirus, Comovirus, Cucumovirus, Fabavirus, Macluravirus, Potexvirus and Potyvirus have been reported in yams (3) and fifteen viruses in these genera have been detected in China. In July 2020, a survey of viral diseases on yam was conducted in plantations of Wenxian and Mengzhou counties in Henan Province, China. Fifty-four leaf samples of Dioscorea opposite showing mosaic and leaf discoloration (Supplementary Fig1) were collected from eight fields (five to ten plants per field). These leaf samples were ground in liquid nitrogen and total RNA was extracted from a portion of the mixed powder using RNAprep Pure Plant Plus Kit (TIANGEN Biotech, Beijing, China). A cDNA library was constructed using NEBNext Ultra RNA Library Prep Kit for Illumina (NEB, USA) after ribosomal RNA depletion using Ribo-off rRNA Depletion Kit (Vazyme Biotech, Nanjing, China), and sequenced on the Illumina NovaSeq 6000 system at the Berry Genomics Corporation (Beijing, China). A total of 87,075 contigs (>200 bp) were generated from de novo assembly (CLC Genomic Workbench 10.0) from a total of 34,656,172 paired-end reads. After BLASTn analysis, three contigs with the length of 1009, 1340 and 1859 nucleotides shared 96.33%, 96.72% and 96.29% nt identity respectively with youcai mosaic virus SX isolate, a tobamovirus (YoMV GenBank accession no. JX422022). In addition to YoMV, broad bean wild virus 2 and yam latent virus were also identified, which had previously been reported in yams in China. To confirm the NGS result, total RNAs were extracted from fifty-four above-mentioned samples and RT-PCR was carried out to amplify a 528 bp fragment of the coat protein (CP) of YoMV by using a pair of specific primers CP gene. PCR products with expected size were obtained from 26 out of 54 samples, and seventeen amplicons of YoMV-CP were sequenced (accession nos. ON052726 to ON052742). The nt sequence identities of CP gene among these seventeen isolates were 99.6%-100%. Furthermore, the near-full-length genomic sequence of YoMV-Do41 isolate was obtained from sample 41 by RT-PCR amplification of four overlapping fragments using the following primer pairs: YoMV-15F/YoMV-1910R, YoMV-1770F/YoMV-3750R, YoMV-3645F/YoMV-5404R and YoMV-4921F/YoMV-6280R (Supplementary Table1). The YoMV-Do41 isolate was 6, 274 nt in length (accession no. ON149803) and shared 89.65% and 97.31% nt identities to As1-2 isolate (GenBank accession no. MW307290) and to SX isolate (accession no. JX422022), respectively.To the best of our knowledge, this is the first report of YoMV infecting yam in China. YoMV has a wide host range including genera Impatiens, Rehmannia, Brassica, Chelidonium, Trifolium, Crossandro, Alstroemeria, Stellaria. This study will serve as an important reference for the host range of YoMV. According to the detection rate infections with YoMV in yam are common in these producing regions. Further studies will be required to determine the infection rate in other producing regions and the potential threat posed by YoMV on yam production should be considered.

Application of CRISPR-Based Human and Bacterial Ribosomal RNA Depletion for SARS-CoV-2 Shotgun Metagenomic Sequencing

The aim of this study is to evaluate the effectiveness of a CRISPR-based human and bacterial ribosomal RNA (rRNA) depletion kit (JUMPCODE Genomics) on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) shotgun metagenomic sequencing in weakly positive respiratory samples. Shotgun metagenomics was performed on 40 respiratory specimens collected from solid organ transplant patients and deceased intensive care unit patients at UCLA Medical Center in late 2020 to early 2021. Human and bacterial rRNA depletion was performed on remnant library pools prior to sequencing by Illumina MiSeq. Data quality was analyzed using Geneious Prime, whereas the identification of SARS-CoV-2 variants and lineages was determined by Pangolin. The average genome coverage of the rRNA-depleted respiratory specimens increased from 72.55% to 93.71% in overall samples and from 29.3% to 83.3% in 15 samples that failed to achieve sufficient genome coverage using the standard method. Moreover, rRNA depletion enhanced genome coverage to over 85% in 11 (73.3%) of 15 low viral load samples with cycle threshold values up to 35, resulting in the identification of genotypes. The CRISPR-based human and bacterial rRNA depletion enhanced the sensitivity of SARS-CoV-2 shotgun metagenomic sequencing, especially in low viral load samples.

Changes of Transcriptomic Landscape in Blasts of Responding and Refractory Acute Myeloid Leukemia Patients after Chemotherapy

Despite many ongoing clinical drug trials and advances in acute myeloid leukemia (AML) therapy, the 3+7 induction regimen with anthracyclines and cytarabine (+/- midostaurin) remains the golden standard of AML treatment. Approximately 40 % of AML patients do not achieve a complete hematological remission (CR) after the first cycle of 3+7 chemotherapy and face an adverse prognosis. One of the main causes of treatment failure is chemoresistance of leukemia cells acquired by various mechanisms, all of which have not been identified as yet. We present here a unique study of transcriptome landscape mapping of separated AML blasts from paired samples collected before and after chemotherapy administration, focusing on differences between responding (RES) and refractory (REF) AML. The aim of this study was to describe transcriptional changes in leukemic blasts between RES and REF AML patients after chemotherapy administration, and to identify molecular pathways involved in reduced sensitivity to chemotherapy. Leukemic blasts were sorted from peripheral blood of AML patients collected at diagnosis (day 0, n=30) and on the third day (day 3, n=16) of 3+7 chemotherapy. CD34+ and CD117+ antibodies were used for blast separation on autoMACS (Miltenyi Biotec). 100 ng of high quality DNAse-treated RNA (RIN>8) was ribodepleted via the RiboCop rRNA Depletion kit (Lexogen) and the library was prepared using the NEBNext Ultra II Directional RNA Library Prep Kit (NEB). Transcriptome was sequenced on NovaSeq (Illumina). For data analysis, we divided patients by primary response status into RES and REF groups based on CR achievement after the first cycle of 3+7 therapy. Quantification of gene expression was performed using StringTie2 software (version 1.3.6). Resulting data were subsequently analyzed and visualized in R software 4.0.0 using edgeR and pheatmap packages. The String and GO databases were used to annotate genes into molecular pathways and biological processes. We identified 75 differentially expressed genes (FDR<0.05) at day 0 between RES (n=15) and REF (n=15) AML patients (Fig.1a). Among genes upregulated (n=62) in REF AML, those previously associated with inferior prognosis such as MN1 (transcriptional regulator), ABCA6 (membrane transporter) and SETBP1 (transcriptional regulator) were identified. On the contrary, PRF1 (involved in killing transformed cells) and TLE1 (negative regulator of NF-κB) were among genes downregulated (n=13) in REF AML. In general, genes upregulated in REF AML were assigned to Golgi membrane, carbohydrate transport and interferon signalling and genes upregulated in RES AML to immune response and the β-catenin/TCF transcriptional complex. In the pairwise analysis (day 0 vs. day 3), we identified 82 differentially expressed genes in RES (Fig.1b, n=6) and 121 differentially expressed genes in REF AML (Fig.1c, n=10). There were 42 genes identically deregulated in both groups and they were annotated into DNA damage/stress response, DNA repair and apoptotic pathways. Next, we compared genes that were deregulated only in RES or REF AML. In RES AML, there was a big cluster of downregulated histone and chromatin remodelling genes that was missing in REF AML. Upregulated genes in RES AML included those with antiproliferative, proapoptotic and p53 stabilizing functions. In REF AML, the principal deregulated genes were those affecting cytoskeleton remodelling (downregulated), p53 signalling network (upregulated) and genotoxicity pathways (upregulated). We identified differences in leukemic blast transcriptome between RES and REF AML before and after chemotherapy administration. The role of some differentially expressed genes has already been elucidated in AML pathogenesis, others deserve a closer look to evaluate their relevance as potential targets for emerging therapies. Instant downregulation of histone genes after chemotherapy administration seems to be a strong sign of RES AML and requires further attention for its use as a biomarker for early stratification into good versus poor responder AML. This project was supported by Ministry of Health of the Czech Republic (00023736, IHBT) and by GA CR (No. 20-19162S). Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Comparative Analysis of rRNA Removal Methods for RNA-Seq Differential Expression in Halophilic Archaea.

Despite intense recent research interest in archaea, the scientific community has experienced a bottleneck in the study of genome-scale gene expression experiments by RNA-seq due to the lack of commercial and specifically designed rRNA depletion kits. The high rRNA:mRNA ratio (80–90%: ~10%) in prokaryotes hampers global transcriptomic analysis. Insufficient ribodepletion results in low sequence coverage of mRNA, and therefore, requires a substantially higher number of replicate samples and/or sequencing reads to achieve statistically reliable conclusions regarding the significance of differential gene expression between case and control samples. Here, we show that after the discontinuation of the previous version of RiboZero (Illumina, San Diego, CA, USA) that was useful in partially or completely depleting rRNA from archaea, archaeal transcriptomics studies have experienced a slowdown. To overcome this limitation, here, we analyze the efficiency for four different hybridization-based kits from three different commercial suppliers, each with two sets of sequence-specific probes to remove rRNA from four different species of halophilic archaea. We conclude that the key for transcriptomic success with the currently available tools is the probe-specificity for the rRNA sequence hybridization. With this paper, we provide insights into the archaeal community for selecting certain reagents and strategies over others depending on the archaeal species of interest. These methods yield improved RNA-seq sensitivity and enhanced detection of low abundance transcripts.

Comparison of rRNA depletion methods for efficient bacterial mRNA sequencing

Current methods of high-throughput RNA sequencing of prokaryotes, including transcriptome analysis or ribosomal profiling, need deep sequencing to achieve sufficient numbers of effective reads (e.g., mapping to mRNA) in order to also find weakly expressed genetic elements. The fraction of high-quality reads mapping to coding RNAs (i.e., mRNA) is mainly influenced by the large content of rRNA and, to a lesser extent, tRNA in total RNA. Thus, depletion of rRNA increases coverage and thus sequencing costs. RiboZero, a depletion kit based on probe hybridisation and rRNA-removal was found to be most efficient in the past, but it was discontinued in 2018. To facilitate comparability with previous experiments and to help choose adequate replacements, we compare three commercially available rRNA depletion kits also based on hybridization and magnetic beads, i.e., riboPOOLs, RiboMinus and MICROBExpress, with the former RiboZero. Additionally, we constructed biotinylated probes for magnetic bead capture and rRNA depletion in this study. Based on E. coli, we found similar efficiencies in rRNA depletion for riboPOOLs and the self-made depletion method; both comparable to the former RiboZero, followed by RiboMinus, succeeded by MICROBExpress. Further, our in-house protocol allows customized species-specific rRNA or even tRNA depletion or depletion of other RNA targets. Both, the self-made biotinylated probes and riboPOOLs, were most successful in reducing the rRNA content and thereby increasing sequencing depth concerning mRNA reads. Additionally, the number of reads matching to weakly expressed genes are increased. In conclusion, the self-made specific biotinylated probes and riboPOOLs are an adequate replacement for the former RiboZero. Both are very efficient in depleting rRNAs, increasing mRNA reads and thus sequencing efficiency.

First Report of Dasheen Mosaic Virus Infecting Typhonium giganteum Engl. (Baifuzi) in Henan Province of China.

Typhonium giganteum Engl. (Baifuzi ) is a perennial plant of the family Araceae. In China, its root is commonly used as an antispasmodic for stroke and cancer treatment (Chi et al. 2010; Gao et al. 2014; Khalivulla et al. 2019). Yuzhou city in Henan Province is the main producing area of T. giganteum Engl., and in July 2020, a survey of viral disease infecting T. giganteum Engl. was conducted in the city. In the surveyed fields (n =5), over 60% of plants displayed varying levels of virus-like symptoms, including mosaic, chlorotic and leaf distortion (Supplementary Figure S1) . To identify possible viral pathogens associated with the disease symptoms afflicting T. giganteum Engl., one leaf each from 25 symptomatic plants was collected and analyzed by high-throughput sequencing (HTS) as well as PCR. For HTS analysis, total RNA was extracted from one pooled sample containing a portion of all abovementioned leaves using RNAprep Pure Plant Plus Kit (TIANGEN Biotech, Beijing, China). After removing ribosomal RNA with Ribo-off rRNA depletion kit (Vazyme Biotech, Nanjing, China), a sequencing library was generated using NEBNext Ultra RNA Library Prep Kit for Illumina (NEB, USA) and sequenced on an Illumina Novaseq6000 sequencing system at Berry Genomics Corporation (Beijing, China). A total of 6,899,143 high-quality clean reads were obtained after trimming and used for contig assembly. BLASTn and BLASTx analyses on the contigs (n = 128,400) showed that one contig (9,245 bp in length) exhibited a sequence identity of 84.0% with the reference sequence of dasheen mosaic virus (DsMV, NCBI reference seq. NC_003537, genus Potyvirus, family Potyviridae) , suggesting infection of the plants by DsMV. No other viral sequences were detected in the sample. To confirm these results, a near full-length genomic sequence of DsMV was obtained from one sample (sample no. 39) by reverse transcription polymerase chain reaction (RT-PCR) of three overlapping fragments with the following primer pairs: DsMV-1F (5'-AAATTAAAACATCTCAACAAAACCTACA-3') /DsMV-4130R (5'-TTCATGGTCCTCGTGGAGTATA-3'), DsMV-3870F (5'-GAGGACGTGAGAATTCAAAGTCT-3')/DsMV-8250R (5'-GTCCAACCTTGCTTGATGCATGC-3'), DsMV-7690F (5'-GGAGCGACTCCTCTTCCAAAGTTGTG-3')/DsMV-10100R (5'-TGAACACCGTGCACGAAGCATCTC-3'). The PCR products were cloned into pMD19-T vector (TAKARA Biotech, Dalian, China) and sequenced. The near full-length genomic sequence of the isolate (DsMV-BF39) was 9,737 nt in length and deposited into GenBank under the accession no. MZ043618. BLASTn analysis of this sequence demonstrated that it shared an identity ranging from 78.6% (MG602234) to 85.6% (MG602227) with various DsMV isolates. To determine whether DsMV was closely associated with the symptoms observed in T. giganteum Engl., leaf tissues from 30 symptomatic plants and 22 asymptomatic plants were analyzed by RT-PCR using primer pairs DsMV-CPF (5'-TGTTCTGTGAACATGATGAAGTTG-3', sense) and DsMV-CPR (5'-GTAACTGTGGCCTGTTTACCAG-3', antisense) targeting a 916 bp fragment of the CP gene of DsMV. Amplicons with the expected size were detected from the 30 symptomatic plants but not from the 22 asymptomatic plants, suggesting a close association between DsMV infection and the observed symptoms. To our knowledge, this is the first report of DsMV infecting T. giganteum Engl.. Further study is needed to identify the specific symptoms induced by this virus in T. giganteum Engl. and to understand the biological characteristics, epidemiology, prevalence of this virus in China.

Abstract 471: Reference materials for tumor mutational burden transcriptome profiling

Abstract Immune Checkpoint Inhibitor (ICI) therapies continue to revolutionize treatment of advanced malignancies. However, identification of individuals who respond to ICI treatment remains challenging. Along with programmed death ligand 1(PD-L1 aka CD274) expression and microsatellite instability, tumor mutational burden (TMB), defined as the number of nonsynonymous mutations per megabase of genome, has emerged as a promising biomarker for differentiating responders from non-responders, especially in non-small cell lung cancer. Although promising, TMB is not a perfect biomarker for ICI efficacy with some individuals responding conversely to expectations. The imperfection of TMB as a prognostic biomarker may result from it being a proxy measurement of potential neoantigens. Indeed, all mutations that contribute to TMB will not be expressed as neoantigens and not all neoantigens will illicit immune responses. In refining ICI response prediction, tumor abundance of nonsynonymous mutations has aided in neoantigen prediction. In order to begin development of quality reference materials for neoantigen prediction, we have characterized the transcriptomes of four tumor cell lines that were previously used to formulate TMB reference materials. Sequencing libraries were prepared with the TruSeq Stranded Total RNA with Illumina Ribo-Zero Plus rRNA Depletion Kit and Invitrogen Collibri Stranded RNA Library Prep Kit from Illumina with Collibri H/M/R rRNA Depletion Kit. The resultant transcriptome libraries were sequenced on an Illumina NextSeq2000 platform and relative transcript counts were determined. Broad ranges of expression were observed among transcripts containing nonsynonymous mutations in each of the tumor cell lines tested. These datasets will serve as benchmarks for others attempting to combine TMB and tumor abundance in predicting neoantigen potential. Citation Format: Matthew G. Butler, Yves Konigshofer, Jessica Dickens, Bharathi Anekella. Reference materials for tumor mutational burden transcriptome profiling [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 471.

Ribo-ODDR: oligo design pipeline for experiment-specific rRNA depletion in Ribo-seq.

MotivationRibosome Profiling (Ribo-seq) has revolutionized the study of RNA translation by providing information on ribosome positions across all translated RNAs with nucleotide-resolution. Yet several technical limitations restrict the sequencing depth of such experiments, the most common of which is the overabundance of rRNA fragments. Various strategies can be employed to tackle this issue, including the use of commercial rRNA depletion kits. However, as they are designed for more standardized RNAseq experiments, they may perform suboptimally in Ribo-seq. In order to overcome this, it is possible to use custom biotinylated oligos complementary to the most abundant rRNA fragments, however currently no computational framework exists to aid the design of optimal oligos.ResultsHere, we first show that a major confounding issue is that the rRNA fragments generated via Ribo-seq vary significantly with differing experimental conditions, suggesting that a ‘one-size-fits-all’ approach may be inefficient. Therefore we developed Ribo-ODDR, an oligo design pipeline integrated with a user-friendly interface that assists in oligo selection for efficient experiment-specific rRNA depletion. Ribo-ODDR uses preliminary data to identify the most abundant rRNA fragments, and calculates the rRNA depletion efficiency of potential oligos. We experimentally show that Ribo-ODDR designed oligos outperform commercially available kits and lead to a significant increase in rRNA depletion in Ribo-seq.Availability and implementationRibo-ODDR is freely accessible at https://github.com/fallerlab/Ribo-ODDR.Supplementary informationSupplementary data are available at Bioinformatics online.

Comparative evaluation for the globin gene depletion methods for mRNA sequencing using the whole blood-derived total RNAs

BackgroundThere are challenges in generating mRNA-Seq data from whole-blood derived RNA as globin gene and rRNA are frequent contaminants. Given the abundance of erythrocytes in whole blood, globin genes comprise some 80% or more of the total RNA. Therefore, depletion of globin gene RNA and rRNA are critical steps required to have adequate coverage of reads mapping to the reference transcripts and thus reduce the total cost of sequencing. In this study, we directly compared the performance of probe hybridization (GLOBINClear Kit and Globin-Zero Gold rRNA Removal Kit) and RNAse-H enzymatic depletion (NEBNext® Globin & rRNA Depletion Kit and Ribo-Zero Plus rRNA Depletion Kit) methods from 1 μg of whole blood-derived RNA on mRNA-Seq profiling. All RNA samples were treated with DNaseI for additional cleanup before the depletion step and were processed for poly-A selection for library generation.ResultsProbe hybridization revealed a better overall performance than the RNAse-H enzymatic depletion method, detecting a higher number of genes and transcripts without 3′ region bias. After depletion, samples treated with probe hybridization showed globin genes at 0.5% (±0.6%) of the total mapped reads; the RNAse-H enzymatic depletion had 3.2% (±3.8%). Probe hybridization showed more junction reads and transcripts compared with RNAse-H enzymatic depletion and also had a higher correlation (R > 0.9) than RNAse-H enzymatic depletion (R > 0.85).ConclusionIn this study, our results showed that 1 μg of high-quality RNA from whole blood could be routinely used for transcriptional profiling analysis studies with globin gene and rRNA depletion pre-processing. We also demonstrated that the probe hybridization depletion method is better suited to mRNA sequencing analysis with minimal effect on RNA quality during depletion procedures.

Optimized design of antisense oligomers for targeted rRNA depletion.

RNA sequencing (RNA-seq) is extensively used to quantify gene expression transcriptome-wide. Although often paired with polyadenylate (poly(A)) selection to enrich for messenger RNA (mRNA), many applications require alternate approaches to counteract the high proportion of ribosomal RNA (rRNA) in total RNA. Recently, digestion using RNaseH and antisense DNA oligomers tiling target rRNAs has emerged as an alternative to commercial rRNA depletion kits. Here, we present a streamlined, more economical RNaseH-mediated rRNA depletion with substantially lower up-front costs, using shorter antisense oligos only sparsely tiled along the target RNA in a 5-min digestion reaction. We introduce a novel Web tool, Oligo-ASST, that simplifies oligo design to target regions with optimal thermodynamic properties, and additionally can generate compact, common oligo pools that simultaneously target divergent RNAs, e.g. across different species. We demonstrate the efficacy of these strategies by generating rRNA-depletion oligos for Xenopus laevis and for zebrafish, which expresses two distinct versions of rRNAs during embryogenesis. The resulting RNA-seq libraries reduce rRNA to <5% of aligned reads, on par with poly(A) selection, and also reveal expression of many non-adenylated RNA species. Oligo-ASST is freely available at https://mtleelab.pitt.edu/oligo to design antisense oligos for any taxon or to target any abundant RNA for depletion.

A reverse transcriptase-mediated ribosomal RNA depletion (RTR2D) strategy for the cost-effective construction of RNA sequencing libraries

RNA sequencing (RNA-seq)-based whole transcriptome analysis (WTA) using ever-evolving next-generation sequencing technologies has become a primary tool for coding and/or noncoding transcriptome profiling. As WTA requires RNA-seq data for both coding and noncoding RNAs, one key step for obtaining high-quality RNA-seq data is to remove ribosomal RNAs, which can be accomplished by using various commercial kits. Nonetheless, an ideal rRNA removal method should be efficient, user-friendly and cost-effective so it can be adapted for homemade RNA-seq library construction. Here, we developed a novel reverse transcriptase-mediated ribosomal RNA depletion (RTR2D) method. We demonstrated that RTR2D was simple and efficient, and depleted human or mouse rRNAs with high specificity without affecting coding and noncoding transcripts. RNA-seq data analysis indicated that RTR2D yielded highly correlative transcriptome landscape with that of NEBNext rRNA Depletion Kit at both mRNA and lncRNA levels. In a proof-of-principle study, we found that RNA-seq dataset from RTR2D-depleted rRNA samples identified more differentially expressed mRNAs and lncRNAs regulated by Nutlin3A in human osteosarcoma cells than that from NEBNext rRNA Depletion samples, suggesting that RTR2D may have lower off-target depletion of non-rRNA transcripts. Collectively, our results have demonstrated that the RTR2D methodology should be a valuable tool for rRNA depletion.

Quality control assessment of the RNA-Seq data generated from liver and pituitary transcriptome of Hereford bulls using StrandNGS software

Background : Quality control (QC) assessment is the most critical step in the high-throughput RNA-seq data analysis to characterize the in-depth understanding of genome and transcriptome assembling to a given reference genome. It provides not only a quick insight into the RNA-seq data quality to allow early identification of good or bad RNA-seq data samples, but also to verify the alignment QC checks for further essential high-throughput bioinformatics analysis such as, identification of novel genetic variants, differentially expressed genes (DEGs), gene network and metabolic pathways. Method : After isolation of total RNA from liver (n=15) and pituitary gland (n=15) tissues of young Hereford bulls, the pooled total RNA (n=30) were fragmented using GeneRead rRNA depletion kit (Qiagen, Hilden, Germany) and cDNA library preparation were preformed using ScriptSeq TM v2 RNA-Seq library preparation kit (Epicentre, illumina, USA), followed by high-throughput sequencing of combined liver and pituitary transcriptome using MiSeq reagent kit v2 (illumina, USA) to obtain high quality of paired-end RNA-seq reads of 251 base-pairs (bps). In this paper, the QC assessment of obtained RNA-seq raw data as well as post-alignment QC of processed RNA-seq data of combined liver and pituitary transcriptome (n=30) of Hereford bulls were performed using the strand NGS software v1.3 (Agilent; http://www.strand-ngs.com/ ) data analysis package. The reads were aligned with Bowtie using default settings against both Bull and Cow genome assembly. Results : Using two runs of MiSeq platform, a total of over 60 million paired-end RNA-seq reads were successfully obtained and submitted to NCBI SRA resources ( https://www.ncbi.nlm.nih.gov/sra?linkname=bioproject_sra_all&from_uid=312148 ). Library complexity plot results revealed 72.02% of duplicate reads with a low library complexity value of 0.28. The pre-alignment QC analysis of raw RNA-seq data revealed the sequence read lengths ranged from 35-251 bp size with more than 50% of all reads with length over 200bp and 10% of reads below 100bp. Conclusion : By testing the RNA-seq methodology on Illumina platform, two MiSeq sequencing runs yielded significantly high quality of 30 million sequencing reads per single MiSeq run. Our initial pre-alignment and post-alignment analysis of RNA-seq data analysis revealed that mapping of the Hereford liver and pituitary gland transcriptome to reference Bos taurus genome was successfully performed, however, more than 50% of all reads with length over 200bp were recovered. Therefore, obtained results concludes that liver and pituitary transcriptome sequencing with rRNA depletion method is less effective than mRNA RNA-seq method.

Abstract 3575: Dysregulated expression of lncRNAs in glioblastoma multiforme and their association with overall survival

Abstract Introduction: Glioblastoma multiforme (GBM) is the most frequent primary brain malignancy of astrocytic origin. The prognosis remains very poor with the median overall survival (OS) being between 12 and 16 months from diagnosis despite early use of conventional medical therapy. Identifying new therapeutic targets, as well as prognostic and predictive biomarkers for accurate stratification of patients is therefore of utmost importance. Long non-coding RNAs (lncRNAs) are regulators of gene expression having critical impact on both physiological processes and the molecular pathology of GBM, indicating their potential as biomarkers and therapeutic targets. Material and Methods: Our study included 219 GBM patients and 29 patients with non-dominant anterior temporal cortexes resected during surgery for intractable epilepsy. Informed consent approved by the local Ethical Commission was obtained from each patient. RNA (RIN &amp;gt; 8) from 77 specimens was used for next-generation RNA sequencing (RNAseq). rRNA depletion and cDNA library preparation were done with RiboCop rRNA Depletion Kit V1.2 (Lexogen) and NEBNext Ultra II Directional RNA Library Prep Kit for Illumina (NEB), respectively. RNAseq was performed using NextSeq 500 High Output Kit and NextSeq 500 instrument (both Illumina). 8,414 lncRNAs and their sequential variants with non-zero RPKM at least in one sample were statistically evaluated. The alignment and target counts were performed with CLC genomic workbench. Selected significantly dysregulated lncRNAs between GBM and non-tumor controls were analyzed in a larger cohort of 188 specimens by qRT-PCR and the expression data normalized to PPIA was then evaluated by Mann-Whitney U test. Results: Statistical analysis revealed 538 (P &amp;lt; 0.001) dysregulated lncRNAs in GBMs compared to non-tumor brain tissue samples. The expression of top 10 downregulated lncRNAs (SNAI3-AS1, LINC00882, RFPL1S, MIR137HG, TTLL7-IT1, PWAR6, LINC00634, LINC00632, DGCR5, LINC00982; logFC ≤ -2; P &amp;lt; 0.001) and 1 upregulated lncRNA (BTN2A3P; logFC ≥ 2; P &amp;lt; 0.001) in GBM and non-tumor controls was successfully validated by qRT-PCR (P &amp;lt; 0.0001). Moreover, the statistical analysis revealed 22 lncRNAs significantly dysregulated between patients with OS less than 12 months and those with OS equal or more than 12 months (P &amp;lt; 0.01). Conclusion: We observed significant dysregulation of lncRNAs in GBM tissues compared to non-tumor controls based on the results of both RNASeq and qRT-PCR. We also found 22 lncRNAs to be dysregulated in relation to overall survival. Our study indicates that lncRNAs could serve as promising diagnostic and prognostic biomarkers in GBM. This work was supported by Ministry of Health of the Czech Republic grant nr. NV18-03-00398, grant of Czech Grant Agency nr. 17-17636S, and by the Ministry of Education, Youth and Sports of the Czech Republic under the project CEITEC 2020 (LQ1601). Citation Format: Marek Vecera, Jan Oppelt, Lenka Radova, Radim Lipina, Stefan Reguli, Martin Smrcka, Radim Jancalek, Michal Filip, Marketa Hermanova, Leos Kren, Jiri Sana, Alena Kopkova, Julia Kovacova, Ondrej Slaby. Dysregulated expression of lncRNAs in glioblastoma multiforme and their association with overall survival [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3575.

Abstract 17010: Metabolic Gene Expression and Mitochondrial Function Are Altered in the Failing Single Ventricle Myocardium

Introduction: Despite current standard of care, heart failure (HF) remains a leading cause of death and indication for transplant in the single ventricle congenital heart disease (SV) population. However, little is known regarding the molecular mechanisms underlying remodeling and eventual HF in SV patients. The purpose of this study was to characterize the transcriptional profile of SV myocardium in both failing (SVHF) and non-failing (SVNF) SV patients compared to biventricular NF controls (BVNF). Furthermore, we conducted high resolution respirometry to assess mitochondrial function in each of these populations. Methods: Library prep was performed using the TruSeq Ribo Zero rRNA depletion kit, and 2x150 total RNAseq (Illumina HiSEQ 4000) was performed on age-matched explanted RV myocardium from BVNF (n=4 biventricular donors), SVNF (n=8 SV primary transplants, normal function), and SVHF (n=9 SV systolic HF transplants). Samples were aligned to hg19 and were normalized and annotated using the edgeR pipeline. Significant changes in gene expression were calculated using an FDR adjusted p-value (q&lt;0.1; p&lt;0.025). Respiration of myocardial mitochondria was measured using a stepwise protocol to evaluate respiratory capacity in an Oroboros Oxygraph system; n=6 SVHF, n=6 SVNF, n=18 BVNF. Results: RNAseq identified 1,007 differentially expressed genes in SVNF and 2,109 in SVHF myocardium relative to BVNF controls. Transcriptome pathway analysis demonstrated multiple pathways that are similarly dysregulated in SVNF and SVHF, while pathways involved in mitochondrial metabolism and function were significantly dysregulated specifically in the SVHF population. Moreover, mitochondrial oxygen flux was significantly decreased, particularly through complexes I and II, in SVHF relative to BVNF controls. Conclusions: Our results provide new insights into SVHF by identifying unique gene expression changes, including those related to metabolism, and impaired mitochondrial function. Together these data suggest dysregulated metabolic gene expression and mitochondrial dysfunction are phenotypes associated with the failing single ventricle and may serve as potential therapeutic targets for the treatment or prevention of HF in the SV population.

Abstract 2459: Clinicopathological subgroups of glioblastoma patients are characterized by specific lncRNA expression patterns

Abstract Introduction: Glioblastoma (GBM) is the most frequent primary brain tumor of astrocytic origin. The prognosis is unfavourable with the median overall survival (OS) being between 12 and 15 months from diagnosis. Identification of new therapeutic targets, as well as new prognostic and predictive biomarkers for more accurate stratification of patients presents significant unmet medical needs. Long non-coding RNAs (lncRNAs) are regulators of gene expression playing important roles in the molecular pathology of GBM, indicating their potential as biomarkers and therapeutics targets. Material and Methods: Our study included 80 GBM patients treated with Stupp protocol and 16 patients with non-dominant anterior temporal cortexes resected during surgery for intractable epilepsy. Informed consent approved by the local Ethical Commission was obtained from each patient. IDH1 mutations and MGMT methylation status were evaluated in all GBMs. RNA (RIN &amp;gt; 8) from 96 specimens was used for next-generation RNA sequencing (RNAseq). rRNA depletion and cDNA library preparation were performed with RiboCop rRNA Depletion Kit V1.2 (Lexogen) and NEBNext Ultra II Directional RNA Library Prep Kit for Illumina (NEB), respectively. RNAseq was done using NextSeq 500 High Output Kit and NextSeq 500 instrument (both Illumina). 24,087 protein-coding and 8,414 non-coding RNAs and their sequential variants with non-zero RPKM at least in one sample underwent statistical evaluation. CLC genomic workbench was used for the alignment and target counts. Results: Statistical analysis revealed 84 (P &amp;lt; 0.001) dysregulated lncRNAs in GBMs compared to non-tumor brain tissue samples. The results also showed 485 dysregulated protein-coding RNAs with P &amp;lt; 0.001 and 24 protein-coding RNAs with P &amp;lt; 0.000001. 35 lncRNAs showed significant dysregulation when lncRNA profiles of GBM tissues with methylated MGMT promoter (≥ 25% methylation) were compared to those with unmethylated promoter (P &amp;lt; 0.01). When lncRNA patterns of GBM samples with mutated IDH1 were compared to those with wild-type IDH1, 60 lncRNAs were found to be significantly dysregulated (P &amp;lt; 0.001). Correlating lncRNA expression patterns with OS uncovered 6 lncRNA signature which enabled identifying patients with significantly worse prognosis (OS &amp;lt; 6 months). Conclusion: We described significant dysregulation of lncRNAs and protein-coding RNAs in GBM tissue compared to non-tumor brain tissue and specific lncRNA patterns linked to MGMT methylation and IDH1 mutation status. We also identified 6 lncRNA signature allowing sensitive prognostic stratification of GBM patients. Our study indicates that lncRNAs could serve as promising diagnostic and prognostic biomarkers in GBM. This work was supported by Ministry of Health of the Czech Republic, grant nr. 15-33158A, 15-34553A, 15-31627A, 15-34678A, 16-31314A, 16-31765A and by grant of Czech Grant Agency nr. 16-18257S. Citation Format: Marek Vecera, Romana Butova, Radim Lipina, Stefan Reguli, Martin Smrcka, Radim Jancalek, Michal Filip, Marketa Hermanova, Leos Kren, Pavol Mojak, Jaroslav Juracek, Tana Machackova, Natalia A. Gablo, Jiri Sana, Ondrej Slaby. Clinicopathological subgroups of glioblastoma patients are characterized by specific lncRNA expression patterns [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2459.

Abstract 3445: ZFAS1 is upregulated in GBM tissue and affects viability and migration of GBM cells in vitro

Abstract Introduction: Glioblastoma multiforme (GBM) is the most frequent primary brain tumor of astrocytic origin characterized by very poor prognosis. Despite conventional therapeutic protocol the prognosis of GBM patients is very poor with median of overall survival ranging between 12 and 15 months from diagnosis. Therefore, many financial charges and lot of effort is spent in research of new therapeutic approaches that could prolong the survival of GBM patients. Long non-coding RNAs (lncRNAs) are a relatively new class of noncoding gene regulators playing critical roles in tumor biology, including GBM. From this perspective, lncRNAs seem to be promising therapeutic targets in GBM patients. Material and Methods: We performed next-generation sequencing analysis of fresh-frozen histopatologically confirmed 45 GBM tissues and 5 non-tumor brain tissues obtained from non-dominant anterior temporal cortexes resected during surgery for intractable epilepsy. Informed consent approved by the local Ethical Commission was obtained from each patient before the treatment. rRNA depletion and cDNA library preparation were performed with GeneRead rRNA Depletion Kit (Qiagen) and NEXTflex Rapid Directional qRNA-Seq Kit (Bioo Scientific), respectively. Sequencing was held using NextSeq 500 High Output Kit and NextSeq 500 instrument (both Illumina). Statistical analysis evaluated 24 087 protein-coding and 8 414 non-coding RNAs and their sequential variants with non-zerou RPKM (Reads Per Kilobase of transcript per Million mapped reads) at least in one sample. We used CLC genomic workbench for the alignment and target counts. Targeted regulation of ZFAS1 level have been carried out by the transient transfection of specific siRNA in GBM stable cell lines (A172, T98G, U87MG, U251). Viability and migration were analyzed in vitro using MTT and scratch wound healing assay, respectively. Results: Statistical analysis has revealed 274 (P &amp;lt; 0.01) deregulated lncRNAs in GBMs in comparison with non-tumor brain samples. Moreover, the results have showed also 489 deregulated proten-coding RNAs with P value less than 0.001 and 26 protein-coding RNAs with P value less than 0.000001. For subsequent in vitro functional analyses was chosen one of the most upregulated lncRNAs in GBM samples ZFAS1. Targeted downregulation of this molecule led to the significant reduction of viability in all examined GBM cell lines. Decreasing of proliferation potential was observed only in A172 a U251 cell lines. Conclusion: We have demonstrated a deregulation of many lncRNAs and protein-coding RNAs in GBM tissue in comparison with non-tumor brain tissue. Moreover, ZFAS1, one of the most upregulated lncRNAs in GBM tissue, is involved in regulation of viability and migration of GBM cell lines in vitro. This work was supported by Ministry of Health of the Czech Republic, grant nr. 15-33158A, 15-34553A, 15-31627A, 15-34678A, 16-31314A, 16-31765A and by grant of Czech Grant Agency nr. 16-18257S. Note: This abstract was not presented at the meeting. Citation Format: Jiri Sana, Marek Vecera, Romana Butova, Jaroslav Juracek, Tana Machackova, Parwez Ahmad, Natalia Anna Gablo, Kamila Souckova, Leos Kren, Radim Lipina, Martin Smrcka, Ondrej Slaby. ZFAS1 is upregulated in GBM tissue and affects viability and migration of GBM cells in vitro [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3445. doi:10.1158/1538-7445.AM2017-3445

Selective Depletion of Abundant RNAs to Enable Transcriptome Analysis of Low-Input and Highly Degraded Human RNA.

Ribosomal RNAs (rRNAs) are extremely abundant, often constituting 80% to 90% of total RNA. Since rRNA sequences are often not of interest in genomic RNA sequencing experiments, rRNAs can be removed from the sample before the library preparation step, in order to prevent the majority of the library and the majority of sequencing reads from being rRNA. Removal of rRNA can be especially challenging for low quality and formalin-fixed paraffin-embedded (FFPE) RNA samples due to the fragmented nature of these RNA molecules. The NEBNext rRNA Depletion Kit (Human/Mouse/Rat) depletes both cytoplasmic (5 S rRNA, 5.8 S rRNA, 18 S rRNA, and 28 S rRNA) and mitochondrial rRNA (12 S rRNA and 16 S rRNA) from total RNA preparations from human, mouse, and rat samples. Due to the high similarity among mammalian rRNA sequences, it is likely that rRNA depletion can also be achieved for other mammals but has not been empirically tested. This product is compatible with both intact and degraded RNA (e.g., FFPE RNA). The resulting rRNA-depleted RNA is suitable for RNA-seq, random-primed cDNA synthesis, or other downstream RNA analysis applications. Regardless of the quality or amount of input RNA, this method efficiently removes rRNA, while retaining non-coding and other non-poly(A) RNAs. The NEBNext rRNA Depletion Kit thus provides a more complete picture of the transcript repertoire than oligo d(T) poly(A) mRNA enrichment methods. © 2016 by John Wiley & Sons, Inc.

Evaluation of Ribosomal RNA Removal Protocols for &amp;lt;i&amp;gt;Salmonella&amp;lt;/i&amp;gt; RNA-Seq Projects

Next generation sequencing is a powerful technology whose application in sequencing entire RNA populations (RNA-Seq) of food-borne pathogens will provide valuable insights. A problem unique to prokaryotic RNA-Seq is removal of ribosomal RNA. Unlike eukaryotic messenger RNA (mRNA), bacterial mRNA species are devoid of polyadenylation at the 3’-end and thus the approach of affinity enrichment of mRNA using oligo-dT probes is not an option. Among several approaches to enriching mRNA molecules, removal of ribosomal RNA (rRNA) by subtractive hybridization has been widely used. This approach is a single-step procedure for which several rRNA-depletion kits are commercially available. We evaluated three commercially available rRNA-depletion kits to determine their respective efficiencies of rRNA removal from Salmonella enterica serovar Typhimurium strain SL1344. The three protocols achieved varying degrees of rRNA depletion and resulted in 8 to 1000-fold enrichment of mRNA. rRNA removal probes from two of the three kits were unable to titrate out 23S rRNA species while removal of 16S rRNA was less efficient. The Ribo-Zero kit was most efficient in eliminating 16S, 23S and 5S ribosomal RNA species from the transcriptome of S. enterica serovar Typhimurium strain SL1344.