This work was supported by funding from the Morgridge Institute for Research and the University of Wisconsin Foundation. We thank Krista Eastman for editorial assistance.

<ol>
	<li>Tang, F., Barbacioru, C., Wang, Y., Nordman, E., Lee, C., Xu, N., Wang, X., Bodeau, J., Tuch, B. B., Siddiqui, A., Lao, K., Surani, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=mRNA-Seq+whole-transcriptome+analysis+of+a+single+cell.">mRNA-Seq whole-transcriptome analysis of a single cell.</a> Nature Methods. 6, 377-382 (2009).</li><li>Armour, C. D., Castle, J. C., Chen, R., Babak, T., Loerch, P., Jackson, S., Shah, J. K., Dey, J., Rohl, C. A., Johnson, J. M., Raymond, C. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Digital+transcriptome+profiling+using+selective+hexamer+priming+for+cDNA+synthesis.">Digital transcriptome profiling using selective hexamer priming for cDNA synthesis.</a> Nature Methods. 6, 647-649 (2009).</li><li>Mortazavi, A., Williams, B. A., McCue, K., Schaeffer, L., Wold, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mapping+and+quantifying+mammalian+transcriptomes+by+RNA-Seq.">Mapping and quantifying mammalian transcriptomes by RNA-Seq.</a> Nature Methods. 5, 621-628 (2008).</li><li>Mamanova, L., Andrews, R. M., James, K. D., Sheridan, E. M., Ellis, P. D., Langford, C. F., Ost, T. W., Collins, J. E., Turner, D. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=FRT-seq+amplification-free,+strand-specific+transcriptome+sequencing.">FRT-seq amplification-free, strand-specific transcriptome sequencing.</a> Nature Methods. 5, 130-132 (2010).</li><li>Sengupta, S., Ruotti, V., Bolin, J., Elwell, A., Hernandez, A., Thomson, J., Stewart, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Highly+consistent,+fully+representative+mRNA-Seq+libraries+from+ten+nanograms+of+total+RNA.">Highly consistent, fully representative mRNA-Seq libraries from ten nanograms of total RNA.</a> Biotechniques. 49, 898-904 (2010).</li><li>Langmead, B., Trapnell, C., Pop, M., Salzberg, S. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ultrafast+and+memory-efficient+alignment+of+short+DNA+sequences+to+the+human+genome.">Ultrafast and memory-efficient alignment of short DNA sequences to the human genome.</a> Genome. Biology. 10, R25-R25 (2009).</li><li>Li, B., Ruotti, V., Stewart, R. M., Thomson, J. A., Dewey, C. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=RNA-Seq+gene+expression+estimation+with+read+mapping+uncertainty.">RNA-Seq gene expression estimation with read mapping uncertainty.</a> Biotechniques. 26, 493-500 (2010).</li><li>Thomson, J. A., Itskovitz-Eldor, J., Shapiro, S. S., Waknitz, M. A., Swiergiel, J. J., Marshall, V. S., Jones, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Embryonic+stem+cell+lines+derived+from+human+blastocysts.">Embryonic stem cell lines derived from human blastocysts.</a> Science. 282, 1145-1147 (1998).</li></ol>

The authors disclose that J.A.T. is a founder, stockowner, consultant and board member of Cellular Dynamics International (CDI). He also serves as scientific advisor to and has financial interests in Tactics II Stem Cell Ventures.

Current protocols for making paired end libraries require between 1 &mu;g9 to 2.5 &mu;g10 starting amount of total RNA. Here we present our linear T7 amplification based (T7LA) method to prepare both single read and paired end Illumina sequencing libraries and show that this method allows generation of libraries from as low as 10 ng of total RNA, producing data that is comparable to that of minimally amplified (MinAmp) libraries made from 1000 fold more starting material (10 &mu;g total RNA). The 10 ng libraries not only identify similar total numbers of genes, but also produce gene expression signatures that are similar (Figures 3a and b). Moreover, both the single read and paired end libraries produced by the T7LA method are very similar to each other (Figure 3c), which allows researchers to compare data generated by libraries made from either protocol. Since these libraries were prepared from human embryonic stem cell RNA, we searched for 30 stem cell specific genes among the libraries and find that almost all of these genes (93-100%) are identified by the libraries made from at least 10 ng of starting total RNA (Figure 4), thus validating our protocol. We believe our protocol would be very useful for researchers, especially in circumstances such as flow sorted cells or laser-micro-dissected tissue where starting material is limiting. In such circumstances, our protocol would allow generation of gene expression data comparable to libraries made from much larger starting quantities since our protocol produces expression profiles comparable across at least 3 orders of magnitude of starting RNA.

<table border="1">
<tbody>
<tr>
<td>Company	</td>
<td>Kit/Reagent</td>
<td>Catalog #</td>
<td>Special Comments</td>
</tr>
<tr>
<td>Ambion	</td>
<td>Fragmentation reagent</td>
<td>AM8740</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Ambion	</td>
<td>Liner Acrylamide</td>
<td>AM9520</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Ambion</td>
<td>MEGAscript T7 Kit</td>
<td>AM1334</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Ambion</td>
<td>Non DEPC treated nuclease free water</td>
<td>AM9932</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Fermentas</td>
<td>dNTP set</td>
<td>R0181</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Fermentas</td>
<td>methylated dNTPs</td>
<td>R0431</td>
<td>For Single Read sample prep only</td>
</tr>
<tr>
<td>Illumina</td>
<td>TruSeq SR Cluster Generation kit v5</td>
<td>GD-203-5001</td>
<td>For Single Read sample prep only</td>
</tr>
<tr>
<td>Illumina		</td>
<td>TruSeq Seq Kit v5 36 cycles</td>
<td>FC-104-5001</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Illumina</td>
<td>Chip Seq Sample Prep Kit</td>
<td>IP-102-1001</td>
<td>For Single Read sample prep only. Can be replaced with NEB DNA sample prep Master Mix Set 1 Cat# E6040S</td>
</tr>
<tr>
<td>Illumina			</td>
<td>TruSeq PE Cluster Generation kit v5</td>
<td>PE-203-5001</td>
<td>For paired end sample prep only</td>
</tr>
<tr>
<td>Illumina			</td>
<td>Paired End Sample Prep Kit</td>
<td>PE-102-1001</td>
<td>For paired end sample prep only</td>
</tr>
<tr>
<td>Invitrogen		</td>
<td>1kb plus ladder</td>
<td>10787-018</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Invitrogen		</td>
<td>E. coli Rnase H</td>
<td>18021-014</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Invitrogen		</td>
<td>Rnase Out</td>
<td>10777-019</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Invitrogen		</td>
<td>2nd strand buffer 5x</td>
<td>10812-014</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Invitrogen		</td>
<td>E. coli DNA polymerase</td>
<td>18010-017</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Invitrogen		</td>
<td>E-gel SYBR safe 2%</td>
<td>G521802</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Invitrogen		</td>
<td>Superscript III (with 5X FS buffer and 0.1M DTT)</td>
<td>18080-085</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Invitrogen		</td>
<td>Trizol</td>
<td>12183555</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Invitrogen		</td>
<td>RNA quibit assay kit</td>
<td>Q32852</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Invitrogen		</td>
<td>dsDNA HS qubit assay kit</td>
<td>Q32851</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Invitrogen		</td>
<td>E. coli DNA ligase</td>
<td>18052-019</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Invitrogen		</td>
<td>T4 DNA Polymerase</td>
<td>18005-025</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Invitrogen		</td>
<td>Ultra Pure Dnase Rnase water</td>
<td>10977-015</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Invitrogen		</td>
<td>Superscript II double stranded cDNA synthesis kit</td>
<td>11917-020</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Invitrogen			</td>
<td>Random Primer (invitrogen)</td>
<td>48190-011</td>
<td>For paired end sample prep only</td>
</tr>
<tr>
<td>IDT			</td>
<td>Not1Nonamer B primer</td>
<td>N/A</td>
<td>For Single Read sample prep only</td>
</tr>
<tr>
<td>IDT		</td>
<td>Oligo dT T7</td>
<td>N/A</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>NEB			</td>
<td>Not1 digestion kit</td>
<td>R0189S</td>
<td>For Single Read sample prep only</td>
</tr>
<tr>
<td>Qiagen		</td>
<td>Rneasy Minelute kit</td>
<td>74204</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Qiagen		</td>
<td>RNEasy Mini Kit (50)</td>
<td>74104</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Qiagen		</td>
<td>Gel purification kit</td>
<td>28604</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Qiagen		</td>
<td>Dnase set</td>
<td>79254</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Qiagen		</td>
<td>Rneasy MinElute kit</td>
<td>74204</td>
<td>&nbsp;</td>
</tr>
<tr>
<td>Zymo Research		</td>
<td>DNA clean and concentrator (250X)</td>
<td>D4014</td>
<td>&nbsp;</td>
</tr>
</tbody>
</table>

single read and paired end mrna-seq illumina libraries from 10 nanograms total rna

Whole transcriptome sequencing by mRNA-Seq is now used extensively to perform global gene expression, mutation, allele-specific expression and other genome-wide analyses. mRNA-Seq even opens the gate for gene expression analysis of non-sequenced genomes. mRNA-Seq offers high sensitivity, a large dynamic range and allows measurement of transcript copy numbers in a sample. Illumina&#x2019;s genome analyzer performs sequencing of a large number (&gt; 107) of relatively short sequence reads (&lt; 150 bp).The &quot;paired end&quot; approach, wherein a single long read is sequenced at both its ends, allows for tracking alternate splice junctions, insertions and deletions, and is useful for de novo transcriptome assembly.
One of the major challenges faced by researchers is a limited amount of starting material. For example, in experiments where cells are harvested by laser micro-dissection, available starting total RNA may measure in nanograms. Preparation of mRNA-Seq libraries from such samples have been described1, 2 but involves significant PCR amplification that may introduce bias. Other RNA-Seq library construction procedures with minimal PCR amplification have been published3, 4 but require microgram amounts of starting total RNA.
Here we describe a protocol for the Illumina Genome Analyzer II platform for mRNA-Seq sequencing for library preparation that avoids significant PCR amplification and requires only 10 nanograms of total RNA. While this protocol has been described previously and validated for single-end sequencing5, where it was shown to produce directional libraries without introducing significant amplification bias, here we validate it further for use as a paired end protocol. We selectively amplify polyadenylated messenger RNAs from starting total RNA using the T7 based Eberwine linear amplification method, coined &quot;T7LA&quot; (T7 linear amplification). The amplified poly-A mRNAs are fragmented, reverse transcribed and adapter ligated to produce the final sequencing library. For both single read and paired end runs, sequences are mapped to the human transcriptome6 and normalized so that data from multiple runs can be compared. We report the gene expression measurement in units of transcripts per million (TPM), which is a superior measure to RPKM when comparing samples7.

Watch this Scientific Journal Video about Single Read and Paired End mRNA-Seq Illumina Libraries from 10 Nanograms Total RNA at JoVE.com

Single Read and Paired End mRNA-Seq Illumina Libraries from 10 Nanograms Total RNA

Here we describe a method for preparation of both single read and paired end Illumina mRNA-Seq sequencing libraries for gene expression analysis based on T7 linear RNA amplification. This protocol requires only 10 nanograms of starting total RNA and generates highly consistent libraries representing whole transcripts.

Whole transcriptome sequencing by mRNA-Seq is now used extensively to perform global gene expression, mutation, allele-specific expression and other ...

single-read-paired-end-mrna-seq-illumina-libraries-from-10-nanograms

Research

JoVE Journal

Biology

39.1K Views.  Morgridge Institute for Research. Here we describe a method for preparation of both single read and paired end Illumina mRNA-Seq sequencing libraries for gene expression analysis based on T7 linear RNA amplification. This protocol requires only 10 nanograms of starting total RNA and generates highly consistent libraries representing whole transcripts.

Video: Single Read and Paired End mRNA-Seq Illumina Libraries from 10 Nanograms Total RNA

Genome-wide Quantification of Translation in Budding Yeast by Ribosome Profiling

Translation of mRNA into proteins is a complex process involving several layers of regulation. It is often assumed that changes in mRNA transcription reflect changes in protein synthesis, but many exceptions have been observed. Recently, a technique called ribosome profiling (or Ribo-Seq) has emerged as a powerful method that allows identification, with high accuracy, which regions of mRNA are translated into proteins and quantification of translation at the genome-wide level. Here, we present a generalized protocol for genome-wide quantification of translation using Ribo-Seq in budding yeast. In addition, combining Ribo-Seq data with mRNA abundance measurements allows us to simultaneously quantify translation efficiency of thousands of mRNA transcripts in the same sample and compare changes in these parameters in response to experimental manipulations or in different physiological states. We describe a detailed protocol for generation of ribosome footprints using nuclease digestion, isolation of intact ribosome-footprint complexes via sucrose gradient fractionation, and preparation of DNA libraries for deep sequencing along with appropriate quality controls necessary to ensure accurate analysis of in vivo translation.

Translational regulation plays an important role in the control of protein abundance. Here, we describe a high-throughput method for quantitative analysis of translation in the budding yeast Saccharomyces cerevisiae.

Translation of mRNA into proteins is a complex process involving several layers of regulation. It is often assumed that changes in mRNA transcription ...

Biochemistry

Sequencing of mRNA from Whole Blood using Nanopore Sequencing

Sequencing in remote locations and resource-poor settings presents unique challenges. Nanopore sequencing can be successfully used under such conditions, and was deployed to West Africa during the recent Ebola virus epidemic, highlighting this possibility. In addition to its practical advantages (low cost, ease of equipment transport and use), this technology also provides fundamental advantages over second-generation sequencing approaches, particularly the very long read length, ability to directly sequence RNA, and real-time availability of data. Raw read accuracy is lower than with other sequencing platforms, which represents the main limitation of this technology; however, this can be partially mitigated by the high read depth generated. Here, we present a field-compatible protocol for sequencing of the mRNAs encoding for Niemann-Pick C1, which is the cellular receptor for ebolaviruses. This protocol encompasses extraction of RNA from animal blood samples, followed by RT-PCR for target enrichment, barcoding, library preparation, and the sequencing run itself, and can be easily adapted for use with other DNA or RNA targets.

Nanopore sequencing is a novel technology that allows cost-effective sequencing in remote locations and resource-poor settings. Here, we present a protocol for sequencing of mRNAs from whole blood that is compatible with such conditions.

Sequencing in remote locations and resource-poor settings presents unique challenges. Nanopore sequencing can be successfully used under such conditions, ...

Genetics

Improving Small RNA-seq: Less Bias and Better Detection of 2'-O-Methyl RNAs

The study of small RNAs (sRNAs) by next-generation sequencing (NGS) is challenged by bias issues during library preparation. Several types of sRNA such as plant microRNAs (miRNAs) carry a 2&#39;-O-methyl (2&#39;-OMe) modification at their 3&#39;&#160;terminal nucleotide. This modification adds another difficulty as it inhibits 3&#39;&#160;adapter ligation. We previously demonstrated that modified versions of the &#39;TruSeq (TS)&#39;&#160;protocol have less bias and an improved detection of 2&#39;-OMe RNAs. Here we describe in detail protocol &#39;TS5&#39;, which showed the best overall performance. TS5 can be followed either using homemade reagents or reagents from the TS kit, with equal performance.

We present a detailed small RNA library reparation protocol with less bias than standard methods and an increased sensitivity for 2&#39;-O-methyl RNAs. This protocol can be followed using homemade reagents to save cost or using kits for convenience.

The study of small RNAs (sRNAs) by next-generation sequencing (NGS) is challenged by bias issues during library preparation. Several types of sRNA such as ...

Analyzing tRNA Dynamics Using AQRNA-seq

AQRNA-seq for Quantifying Small RNAs

AQRNA-seq provides a direct linear relationship between sequencing read counts and small RNA copy numbers in a biological sample, thus enabling accurate quantification of the pool of small RNAs. The AQRNA-seq library preparation procedure described here involves the use of custom-designed sequencing linkers and a step for reducing methylation RNA modifications that block reverse transcription processivity, which results in an increased yield of full-length cDNAs. In addition, a detailed implementation of the accompanying bioinformatics pipeline is presented. This demonstration of AQRNA-seq was conducted through a quantitative analysis of the 45 tRNAs in Mycobacterium bovis BCG harvested on 5 selected days across a 20-day time course of nutrient deprivation and 6 days of resuscitation. Ongoing efforts to improve the efficiency and rigor of AQRNA-seq will also be discussed here. This includes exploring methods to obviate gel purification for mitigating primer dimer issues after PCR amplification and to increase the proportion of full-length reads to enable more accurate read mapping. Future enhancements to AQRNA-seq will be focused on facilitating automation and high-throughput implementation of this technology for quantifying all small RNA species in cell and tissue samples from diverse organisms.

Author Spotlight: AQRNA-seq Role in Mapping Small RNAs and Unraveling Protein Translation Mechanisms

Absolute quantification RNA sequencing (AQRNA-seq) is a technology developed to quantify the landscape of all small RNAs in biological mixtures. Here, both the library preparation and data processing steps of AQRNA-seq are demonstrated, quantifying changes in the transfer RNA (tRNA) pool in Mycobacterium bovis BCG during starvation-induced dormancy.

AQRNA-seq provides a direct linear relationship between sequencing read counts and small RNA copy numbers in a biological sample, thus enabling accurate ...

Preparation of Small RNA Libraries for Sequencing from Early Mouse Embryos

MicroRNAs (miRNAs) are important for the complex regulation of cell fate decisions and developmental timing. In vivo studies of the contribution of miRNAs during early development are technically challenging due to the limiting cell number. Moreover, many approaches require a miRNA of interest to be defined in assays such as northern blotting, microarray, and qPCR. Therefore, the expression of many miRNAs and their isoforms have not been studied during early development. Here, we demonstrate a protocol for small RNA sequencing of sorted cells from early mouse embryos to enable relatively unbiased profiling of miRNAs in early populations of neural crest cells. We overcome the challenges of low cell input and size selection during library preparation using amplification and gel-based purification. We identify embryonic age as a variable accounting for variation between replicates and stage-matched mouse embryos must be used to accurately profile miRNAs in biological replicates. Our results suggest that this method can be broadly applied to profile the expression of miRNAs from other lineages of cells. In summary, this protocol can be used to study how miRNAs regulate developmental programs in different cell lineages of the early mouse embryo.

We describe a technique for profiling microRNAs in early mouse embryos. This protocol overcomes the challenge of low cell input and small RNA enrichment. This assay can be used to analyze changes in miRNA expression over time in different cell lineages of the early mouse embryo.

MicroRNAs (miRNAs) are important for the complex regulation of cell fate decisions and developmental timing. In vivo studies of the contribution of miRNAs ...

Developmental Biology

Unbiased Deep Sequencing of RNA Viruses from Clinical Samples

Here we outline a next-generation RNA sequencing protocol that enables de novo assemblies and intra-host variant calls of viral genomes collected from clinical and biological sources. The method is unbiased and universal; it uses random primers for cDNA synthesis and requires no prior knowledge of the viral sequence content. Before library construction, selective RNase H-based digestion is used to deplete unwanted RNA &#8212; including poly(rA) carrier and ribosomal RNA &#8212; from the viral RNA sample. Selective depletion improves both the data quality and the number of unique reads in viral RNA sequencing libraries. Moreover, a transposase-based &#39;tagmentation&#39; step is used in the protocol as it reduces overall library construction time. The protocol has enabled rapid deep sequencing of over 600 Lassa and Ebola virus samples-including collections from both blood and tissue isolates-and is broadly applicable to other microbial genomics studies.

This protocol describes a rapid and broadly applicable method for unbiased RNA-sequencing of viral samples from human clinical isolates.

Here we outline a next-generation RNA sequencing protocol that enables de novo assemblies and intra-host variant calls of viral genomes collected from ...

Medicine

Single-cell RNA Sequencing of Fluorescently Labeled Mouse Neurons Using Manual Sorting and Double In Vitro Transcription with Absolute Counts Sequencing (DIVA-Seq)

Single-cell RNA sequencing (RNA-seq) is now a widely implemented tool for assaying gene expression. Commercially available single-cell RNA-sequencing platforms process all input cells indiscriminately. Sometimes, fluorescence-activated cell sorting (FACS) is used upstream to isolate a specifically labeled population of interest. A limitation of FACS is the need for high numbers of input cells with significantly labeled fractions, which is impractical for collecting and profiling rare or sparsely labeled neuron populations from the mouse brain. Here, we describe a method for manually collecting sparse fluorescently labeled single neurons from freshly dissociated mouse brain tissue. This process allows for capturing single-labeled neurons with high purity and subsequent integration with an in vitro transcription-based amplification protocol that preserves endogenous transcript ratios. We describe a double linear amplification method that uses unique molecule identifiers (UMIs) to generate individual mRNA counts. Two rounds of amplification results in a high degree of gene detection per single cell.

Single-cell RNA Sequencing of Fluorescently Labeled Mouse Neurons Using Manual Sorting and Double In Vitro Transcription with Absolute Counts Sequencing DIVA-Seq

This protocol describes the manual sorting procedure to isolate single fluorescently labeled neurons followed by in vitro transcription-based mRNA amplification for high-depth single-cell RNA sequencing.

Single-cell RNA sequencing (RNA-seq) is now a widely implemented tool for assaying gene expression. Commercially available single-cell RNA-sequencing ...

Neuroscience

3' End Sequencing Library Preparation with A-seq2

Studies in the last decade have revealed a complex and dynamic variety of pre-mRNA cleavage and polyadenylation reactions. mRNAs with long 3&#39; untranslated regions (UTRs) are generated in differentiated cells whereas proliferating cells preferentially express transcripts with short 3&#39;UTRs. We describe the A-seq protocol, now at its second version, which was developed to map polyadenylation sites genome-wide and study the regulation of pre-mRNA 3&#39; end processing. Also this current protocol takes advantage of the polyadenylate (poly(A)) tails that are added during the biogenesis of most mammalian mRNAs to enrich for fully processed mRNAs. A DNA adaptor with deoxyuracil at its fourth position allows the precise processing of mRNA 3&#39; end fragments for sequencing. Not including the cell culture and the overnight ligations, the protocol requires about 8 h hands-on time. Along with it, an easy-to-use software package for the analysis of the derived sequencing data is provided. A-seq2 and the associated analysis software provide an efficient and reliable solution to the mapping of pre-mRNA 3&#39; ends in a wide range of conditions, from 106 or fewer cells.

This protocol describes a method for mapping pre-mRNA 3&#39; end processing sites.

Studies in the last decade have revealed a complex and dynamic variety of pre-mRNA cleavage and polyadenylation reactions. mRNAs with long 3&#39; ...

Creating Robust Bisulfite-mRNA Libraries for Transcriptome-Wide Mapping

Enrichment of mRNA and Bisulfite-mRNA Library Preparation for Next-Generation Sequencing

RNA post-transcriptional modifications in various types of RNA transcripts are associated with diverse RNA regulation in eukaryotic cells. Aberrant RNA 5-methylcytosine modifications and the dysregulated expression of RNA methyltransferases have been shown to be associated with various diseases, including cancers. Transcriptome-wide bisulfite-sequencing was developed to characterize the positions and the quantitative cytosine methylation levels in the bisulfite-converted RNA at the base-pair resolution. Herein, this protocol presents the procedures of two rounds of poly(A) RNA purification, three cycles of bisulfite reaction, and library preparation in detail to allow the transcriptome-wide mapping of mRNA 5-methylcytosine modification sites. The assessment of RNA quantity and quality after the main reaction is essential to monitor RNA integrity and is a critical step for ensuring high-quality sequencing libraries. Ideally, the procedures can be completed within three days. With this protocol, using high-quality total RNA as the input can practically build up robust bisulfite-mRNA libraries for next-generation sequencing from the sample of interest.

Author Spotlight: Decoding RNA Methylation's Role in Pancreatic Cancer - A Single-Base Resolution Study 

This protocol provides an easy-to-follow workflow to conduct poly(A) RNA purification, bisulfite conversion, and library preparation using standardized equipment for a biological sample of interest.

RNA post-transcriptional modifications in various types of RNA transcripts are associated with diverse RNA regulation in eukaryotic cells. Aberrant RNA ...

Isolation and Profiling of Single Nuclei from Frozen Mammalian Tissues

A Simple, Quick, and Partially Automated Protocol for the Isolation of Single Nuclei from Frozen Mammalian Tissues for Single Nucleus Sequencing

Single-cell and single-nucleus RNA sequencing have become common laboratory applications due to the wealth of transcriptomic information that they provide. Single nucleus RNA sequencing, particularly, is useful for investigating gene expression in difficult-to-dissociate tissues. Furthermore, this approach is also compatible with frozen (archival) material. Here, we describe a protocol to isolate high-quality single nuclei from frozen mammalian tissues for downstream single nucleus RNA sequencing in a partially-automated manner using commercially available instruments and reagents. Specifically, a robotic dissociator is used to automate and standardize tissue homogenization, followed by an optimized chemical gradient to filter the nuclei. Lastly, we accurately and automatically count the nuclei using an automated fluorescent cell counter. The performance of this protocol is demonstrated on mouse brain, rat kidney, and cynomolgus liver and spleen tissue. This protocol is straightforward, rapid, and readily adaptable to various mammalian tissues without requiring extensive optimization and provides good quality nuclei for downstream single nuclei RNA sequencing.

Author Spotlight: Enhancing Drug Discovery - Development of Automated, Standardized Protocols for Nuclei Extraction from Frozen Tissues 

The study describes a simple, quick, and partially automated protocol to isolate high-quality nuclei from frozen mammalian tissues for downstream single nuclei RNA sequencing.