Funding for this work was provided by the University of San Diego, the National Science Foundation Graduate Research Fellowship Program, NIH grant R01-HG007836, and by the Korean Ministry of Science, ICT and Future Planning.
Earlier versions of a several figures were first published in "Hoople, G. D. et al. Gel-seq: whole-genome and transcriptome sequencing by simultaneous low-input DNA and RNA library preparation using semi-permeable hydrogel barriers. Lab on a Chip 17, 2619-2630, doi:10.1039/c7lc00430c (2017)." Lab on a Chip has sanctioned the reuse of figures in this publication.

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	<li>Mawy, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Single-cell+sequencing.">Single-cell sequencing.</a> Nat Methods. 11 (1), 18 (2014).</li><li>Gole, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Massively+parallel+polymerase+cloning+and+genome+sequencing+of+single+cells+using+nanoliter+microwells.">Massively parallel polymerase cloning and genome sequencing of single cells using nanoliter microwells.</a> Nat Biotech. 31 (12), 1126-1132 (2013).</li><li>Sasagawa, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quartz-Seq:+a+highly+reproducible+and+sensitive+single-cell+RNA-Seq+reveals+non-genetic+gene+expression+heterogeneity.">Quartz-Seq: a highly reproducible and sensitive single-cell RNA-Seq reveals non-genetic gene expression heterogeneity.</a> Genome Biol. 14 (4), 31 (2013).</li><li>Ramsk&#246;ld, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Full-length+mRNA-Seq+from+single-cell+levels+of+RNA+and+individual+circulating+tumor+cells.">Full-length mRNA-Seq from single-cell levels of RNA and individual circulating tumor cells.</a> Nat Biotechnol. 30 (8), 777-782 (2012).</li><li>Shapiro, E., Biezuner, T., Linnarsson, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Single-cell+sequencing-based+technologies+will+revolutionize+whole-organism+science.">Single-cell sequencing-based technologies will revolutionize whole-organism science.</a> Nat Rev Genet. 14 (9), 618-630 (2013).</li><li>Navin, N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tumour+evolution+inferred+by+single-cell+sequencing.">Tumour evolution inferred by single-cell sequencing.</a> Nature. 472 (7341), 90-94 (2011).</li><li>Hoople, G. D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gel-seq:+whole-genome+and+transcriptome+sequencing+by+simultaneous+low-input+DNA+and+RNA+library+preparation+using+semi-permeable+hydrogel+barriers.">Gel-seq: whole-genome and transcriptome sequencing by simultaneous low-input DNA and RNA library preparation using semi-permeable hydrogel barriers.</a> Lab Chip. 17, 2619-2630 (2017).</li><li>Macaulay, I. C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=G&amp;T-seq:+parallel+sequencing+of+single-cell+genomes+and+transcriptomes.">G&amp;T-seq: parallel sequencing of single-cell genomes and transcriptomes.</a> Nat Methods. 12 (6), 519-522 (2015).</li><li>Dey, S. S., Kester, L., Spanjaard, B., Bienko, M., van Oudenaarden, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Integrated+genome+and+transcriptome+sequencing+of+the+same+cell.">Integrated genome and transcriptome sequencing of the same cell.</a> Nat Biotechnol. 33 (3), 285-289 (2015).</li><li>Gopal, A., Zhou, Z. H., Knobler, C. M., Gelbart, W. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Visualizing+large+RNA+molecules+in+solution.">Visualizing large RNA molecules in solution.</a> RNA. 18 (2), 284-299 (2012).</li><li>. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=SDS-PAGE+Gel.">SDS-PAGE Gel.</a> Cold Spring Harb Protoc. 2015 (7), 087908 (2015).</li><li>Lake, B. B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neuronal+subtypes+and+diversity+revealed+by+single-nucleus+RNA+sequencing+of+the+human+brain.">Neuronal subtypes and diversity revealed by single-nucleus RNA sequencing of the human brain.</a> Science. 352 (6293), (2016).</li><li>Lee, P. Y., Costumbrado, J., Hsu, C. -. Y., Kim, Y. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Agarose+Gel+Electrophoresis+for+the+Separation+of+DNA+Fragments.">Agarose Gel Electrophoresis for the Separation of DNA Fragments.</a> J Vis Exp. (62), e3923 (2012).</li><li>Qubit 3.0 Fluorometer Manual. MAN0010866. Life Technologies Available from: <a target="_blank" href="https://tools.thermofisher.com/content/sfs/manuals/qubit_3_fluorometer_man.pd">https://tools.thermofisher.com/content/sfs/manuals/qubit_3_fluorometer_man.pd</a> (2017)</li><li>Vitak, S. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sequencing+thousands+of+single-cell+genomes+with+combinatorial+indexing.">Sequencing thousands of single-cell genomes with combinatorial indexing.</a> Nat Methods. 14 (3), 302-308 (2017).</li><li>Illumina. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Nextera &#174; XT DNA Library Preparation Kit. , (2017).</li><li>Takara Bio USA Inc. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> SMART-Seq v4 Ultra Low Input RNA Kit for Sequencing User Manual. , (2016).</li><li>Kurimoto, K., Yabuta, Y., Ohinata, Y., Saitou, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Global+single-cell+cDNA+amplification+to+provide+a+template+for+representative+high-density+oligonucleotide+microarray+analysis.">Global single-cell cDNA amplification to provide a template for representative high-density oligonucleotide microarray analysis.</a> Nat Protoc. 2 (3), 739-752 (2007).</li></ol>

KZ is co-founder and Scientific Advisor of Singlera Genomics Inc.

There are several critical steps associated with the Gel-seq device fabrication as well as the protocol itself. During fabrication, we recommend starting with the prescribed layer thicknesses for the various regions of the gel. We spent significant time testing different fabrication options and the protocol described here produces the best devices for the cassettes listed in the Table of Materials and Reagents. If researchers use an alternative cassette system, they may find it necessary to tweak the vol...

Next generation sequencing (NGS) has had a profound impact on the way genetics research is conducted. Where researchers once focused on sequencing the genome of an entire species, it is now possible to sequence the genome of a single tumor or even a single cell in one experiment.1 NGS has also made it cost effective to sequence the RNA transcripts found within a cell, a collection of data known as the transcriptome. The ability to amplify and sequence either DNA or RNA from small starting samples has only been achieved in the last five years.2,3,4 Unfortunately, standard protocols are incompatible and researchers must choose whether to sequence DNA or RNA for a given sample. When a starting sample is large enough, it can be split in half. At smaller scales, however, loss of material due to splitting samples can affect library quality, and pooling of samples can average out interesting variations between cells.5 Furthermore, researchers are increasingly interested in examining samples that cannot be split, such as single cells or small heterogeneous tumor biopsies.6
To address this problem, three protocols have recently been developed to sequence both DNA and RNA from the same starting sample: Gel-seq7, G&#38;T-seq8, and DR-seq9. This article presents a detailed protocol for Gel-seq, which can be used to simultaneously generate DNA and RNA libraries from as few as 100 cells at negligible added cost. The novel aspect of Gel-seq is the ability to separate DNA and RNA based exclusively on size using low cost hydrogel matrices. The core innovation of the Gel-Seq protocol is the physical separation of DNA from RNA. This separation is achieved electrophoretically using a combination of polyacrylamide membranes that take advantage of the size differences between these molecules. To put these size differences in context, consider how DNA and RNA are imaged: while DNA exists on the micron-scale and can be viewed using traditional microscopes, RNA exists on the nanometer scale and must be imaged using complex techniques such as cryo-electron microscopy.10
The approach to separating DNA and RNA in this protocol is shown in Figure 1. The left panel shows DNA and RNA free floating in solution near a membrane. When an electric field is applied, as shown in the right panel, DNA and RNA experience an electrophoretic force that induces migration through the membrane. By tuning the membrane properties, we have created a semi-permeable membrane that separates DNA from RNA. The DNA molecules are pushed against the membrane, but become entangled at the edge because of their large size. Small RNA molecules, on the other hand, can reconfigure and weave their way through the membrane. This process, known as reptation, is similar to the way a snake moves through grass. Eventually these RNA molecules are stopped by a second, high-density membrane that is too difficult for even smaller polymers (&#62;200 base pairs) to wriggle through. Once physically separated, DNA and RNA can be recovered and processed to generate information about both the genome and transcriptome. While we can separate DNA and RNA, we have found better results are obtained if the RNA is reverse transcribed to cDNA before separation. The cDNA/RNA hybrids are more stable than RNA alone and can still pass through the low-density membrane.
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/57315/57315fig1.jpg" /> 
Figure 1. Gel-seq Operating Principle.&#160;The underlying principle used to physically separate DNA and RNA. In an applied electric field, small RNA molecules migrate through the low-density membrane but large DNA molecules are trapped at the surface. This figure was reproduced from Ref. 7 with permission from the Royal Society of Chemistry.&#160;<a href="//cloudflare.jove.com/files/ftp_upload/57315/57315fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
This paper describes in detail both the fabrication of the Gel-seq device and the biological protocol to generate paired DNA and RNA libraries. An overview of both is shown in Figure 2. The device is fabricated by layering three different density polyacrylamide gels on top of each other in a process similar to creating standard stacking gels.11 The biological protocol starts with 100 - 1000 cells suspended in PBS. The cells are lysed and the RNA is converted into cDNA before the device is used to separate the genomic DNA from the cDNA/RNA hybrids. After separation and recovery, genomic and transcriptomic libraries are prepared using a process that closely follows the standard whole-genome library preparation kit protocol. Further detail about the development and validation of Gel-seq can be read in the Lab on a Chip publication &#34;Gel-seq: whole-genome and transcriptome sequencing by simultaneous low-input DNA and RNA library preparation using semi-permeable hydrogel barriers.&#34;7
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/57315/57315fig2.jpg" /> 
Figure 2. Gel-seq Protocol.&#160;An overview of the steps to fabricate the Gel-seq device and the protocol to generated paired DNA and RNA libraries. Portions of this figure were reproduced from Ref. 7 with permission from the Royal Society of Chemistry.&#160;<a href="//cloudflare.jove.com/files/ftp_upload/57315/57315fig2large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
To generate DNA and RNA libraries from single cells, researchers should consider using either G&#38;T-seq or DR-seq. G&#38;T-Seq, like Gel-seq, relies on a physical separation of RNA from genomic DNA. This approach relies on messenger RNA&#39;s (mRNA) 3&#8242; polyadenylated tail as a pull-down target. The mRNA is captured on a magnetic bead using a biotinylated oligo-dT primer. Once the mRNA has been captured the beads are held in place with a magnet and the supernatant containing the genomic DNA can be removed and transferred to another tube. After this physical separation is complete, separate libraries can be generated from the mRNA and DNA.8 This approach works well if the RNA of interest is polyadenylated, however it cannot be used to study non-polyadenylated transcripts, such as ribosomal RNA, tRNA, or RNA from prokaryotes.
DR-seq relies on a pre-amplification step where both DNA and cDNA derived from RNA are amplified in the same tube. The sample is then split in two and processed in parallel to prepare DNA- and RNA-seq libraries. To distinguish between genomic DNA and the cDNA derived from RNA, DR-seq takes a computational approach. Sequences where only exons are present are computationally suppressed in the genomic DNA data, as those could have originated from either DNA or RNA.9 An advantage of this approach is that the DNA and cDNA/RNA need not be physically separated as is done in Gel-seq and G&#38;T-seq. The drawback, however, is that DR-seq requires a priori knowledge of the genome and transcriptome (i.e., exons versus introns), and might not be ideal for applications such as sequencing of nuclei, in which many transcripts are not yet fully spliced and still contain introns.12
The novel aspect of Gel-seq is the ability to separate DNA and RNA in hundreds of cells based exclusively on size. This method requires no a priori knowledge of the genome or transcriptome, is robust against incomplete splicing, and is not limited to poly-adenylated transcripts. For applications where a researcher can start with at least 100 cells, Gel-seq provides a straightforward approach using cheap and widely-available materials.

<table><tbody><tr><td>&lt;em&gt;Reagents&lt;/em&gt;</td><td></td><td></td><td></td></tr><tr><td>Acrylamide Monomer</td><td>Sigma Aldrich</td><td>A8887-100G</td><td></td></tr><tr><td>Ammonium Persulfate</td><td>Sigma Aldrich</td><td>A3678-25G</td><td></td></tr><tr><td>Ampure XP Beads</td><td>Beckman Coulter</td><td>A63880</td><td>Referred to in the text as solid phase reversible immobilization (SPRI) beads</td></tr><tr><td>DNA Gel Loading Dye (6x)</td><td>ThermoFisher Scientific</td><td>R0611</td><td>Referred to in the text as 6X loading dye</td></tr><tr><td>Ethyl alcohol</td><td>Sigma Aldrich</td><td>E7023-500ML</td><td></td></tr><tr><td>KAPA SYBR FAST One-Step qRT-PCR Kits</td><td>Kapa BioSystems</td><td>7959613001</td><td>Referred to in the text as 2X qPCR mix</td></tr><tr><td>N,N&amp;prime;-Methylenebis(acrylamide)&amp;nbsp;</td><td>Sigma Aldrich</td><td>146072-100G</td><td>Also known as bis-acrylamide</td></tr><tr><td>NexteraXT DNA Library Preparation Kit (referred to in the text as library preparation kit)</td><td>Illumina</td><td>FC-131-1024</td><td>Includes: TD (referred to in the text as transposase buffer), ATM (referred to in the text as transposase), NT (referred to in the text as transposase stop buffer), and NPM (Referred to in the text as library prep PCR mix)</td></tr><tr><td>Nuclease Free Water</td><td>Millipore</td><td>3098</td><td></td></tr><tr><td>Protease</td><td>Qiagen</td><td>19155</td><td></td></tr><tr><td>SMART-Seq v4 Kit (referred to in the text as whole-transcript amplification (WTA) kit)</td><td>Takara/Clontech</td><td>634888</td><td>Includes: Lysis buffer, RNase inhibitor, 3&amp;rsquo; SMART-Seq CDS Primer II A (referred to in the text as RT primer), 5X Ultra Low First Strand Buffer (referred to in the text as first strand buffer), SMART-Seq v4 Oligonucleotide (referred to in the text as template switch oligonucleotide (TSO)), SMART-Scribe Reverse Transcriptase (referred to in the text as reverse transcriptase), and PCR Primer II A (referred to in the text as cDNA PCR primer)</td></tr><tr><td>Random hexamer with WTA adapter&amp;nbsp;</td><td>IDT</td><td>n/a</td><td>5&amp;prime;-AAGCAGTGGTATCAACGCAGAGTAC-NNNNNN-3&amp;prime;</td></tr><tr><td>Sucrose</td><td>Sigma Aldrich</td><td>S0389-500G</td><td></td></tr><tr><td>TEMED</td><td>Sigma Aldrich</td><td>T9281-25ML</td><td></td></tr><tr><td>DNA AWAY Surface Decontaminant</td><td>ThermoFisher Scientific</td><td>7010PK&amp;nbsp;&amp;nbsp;</td><td>Referred to in the text as DNA removal product</td></tr><tr><td>Tris-Borate-EDTA buffer (10X concentration)</td><td>Sigma Aldrich</td><td>T4415-1L</td><td></td></tr><tr><td>SYBR Gold Nucleic Acid Gel Stain (10,000X Concentrate in DMSO)</td><td>ThermoFisher Scientific</td><td>S11494</td><td>Referred to in the text as gel stain</td></tr><tr><td>&lt;em&gt;Equipment&lt;/em&gt;</td><td></td><td></td><td></td></tr><tr><td>BD Precisionglide&amp;nbsp;syringe needles, gauge 18</td><td>Sigma Aldrich</td><td>Z192554</td><td>Any equivalent hardware is acceptable</td></tr><tr><td>Branson CPX series ultrasonic bath</td><td>Sigma Aldrich</td><td>Z769363</td><td>Any equivalent hardware is acceptable</td></tr><tr><td>Empty Gel Cassettes, mini, 1.0 mm</td><td>ThermoFisher Scientific</td><td>NC2010</td><td>Any equivalent hardware is acceptable</td></tr><tr><td>Mesh Filter Plate - Corning&amp;nbsp;HTS Transwell 96 well permeable supports - 8.0 &amp;micro;m pore size</td><td>Sigma Aldrich</td><td>CLS3374</td><td>Referred to in the text as 8 um mesh filter plate</td></tr><tr><td>PowerPac HC Power Supply</td><td>Bio-Rad</td><td>1645052</td><td>Any equivalent hardware is acceptable</td></tr><tr><td>Qubit Fluorometer</td><td>ThermoFisher Scientific</td><td>Q33216</td><td>Any equivalent hardware is acceptable</td></tr><tr><td>Vacufuge Concentrator</td><td>Eppendorf</td><td>22822993</td><td>Any equivalent hardware is acceptable</td></tr><tr><td>XCell SureLock Mini-Cell system</td><td>ThermoFisher Scientific</td><td>EI0001</td><td>Any equivalent hardware is acceptable</td></tr><tr><td>Bio-Rad CFX96 Touch Real-Time PCR Detection System</td><td>Bio-Rad</td><td>1855195&amp;nbsp;</td><td>Any equivalent hardware is acceptable</td></tr><tr><td>Amersham UVC 500 Ultraviolet Crosslinker</td><td>GE Healthcare Life Sciences</td><td>UVC500-115V</td><td>Discontinued, any equivalent hardware is acceptable</td></tr><tr><td>Gel Doc XR+ Gel Documentation System</td><td>Bio-Rad</td><td>1708195</td><td>Referred to in the text as gel imager</td></tr><tr><td>Dark Reader Transilluminator</td><td>Clare Chemical Research</td><td>DR89</td><td>Referred to in the text as UV transilluminator</td></tr><tr><td>&amp;nbsp;Ultrasonic&amp;nbsp;Bath</td><td>Bransonic</td><td>1207K35</td><td>Any equivalent ultrasonic bath is acceptable.</td></tr></tbody></table>

gel-seq: a method for simultaneous sequencing library preparation of dna and rna using hydrogel matrices

The ability to amplify and sequence either DNA or RNA from small starting samples has only been achieved in the last five years. Unfortunately, the standard protocols for generating genomic or transcriptomic libraries are incompatible and researchers must choose whether to sequence DNA or RNA for a particular sample. Gel-seq solves this problem by enabling researchers to simultaneously prepare libraries for both DNA and RNA starting with 100 - 1000 cells using a simple hydrogel device. This paper presents a detailed approach for the fabrication of the device as well as the biological protocol to generate paired libraries. We designed Gel-seq so that it could be easily implemented by other researchers; many genetics labs already have the necessary equipment to reproduce the Gel-seq device fabrication. Our protocol employs commonly-used kits for both whole-transcript amplification (WTA) and library preparation, which are also likely to be familiar to researchers already versed in generating genomic and transcriptomic libraries. Our approach allows researchers to bring to bear the power of both DNA and RNA sequencing on a single sample without splitting and with negligible added cost.

The physical separation of gDNA and cDNA/RNA hybrids in the Gel-seq device can be visualized through fluorescent gel imaging; a representative result is shown in Figure 3. Panel A shows the fabricated Gel-seq device; false color has been added to distinguish the different gel regions. Panel B shows a close up of four different separations used for validation. The third lane, a negative control, represents background and shows that there is no autoflourescence...

Watch this Scientific Journal Video about Gel-seq: A Method for Simultaneous Sequencing Library Preparation of DNA and RNA Using Hydrogel Matrices at JoVE.com

Gel-seq: A Method for Simultaneous Sequencing Library Preparation of DNA and RNA Using Hydrogel Matrices

Gel-seq enables researchers to simultaneously prepare libraries for both DNA- and RNA-seq at negligible added cost starting from 100 - 1000 cells using a simple hydrogel device. This paper presents a detailed approach for the fabrication of the device as well as the biological protocol to generate paired libraries.

The ability to amplify and sequence either DNA or RNA from small starting samples has only been achieved in the last five years. Unfortunately, the ...

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Bioengineering

8.9K Views.  University of San Diego. Gel-seq enables researchers to simultaneously prepare libraries for both DNA- and RNA-seq at negligible added cost starting from 100 - 1000 cells using a simple hydrogel device. This paper presents a detailed approach for the fabrication of the device as well as the biological protocol to generate paired libraries.

Video: Gel-seq: A Method for Simultaneous Sequencing Library Preparation of DNA and RNA Using Hydrogel Matrices

Automated Gel Size Selection to Improve the Quality of Next-generation Sequencing Libraries Prepared from Environmental Water Samples

Next-generation sequencing of environmental samples can be challenging because of the variable DNA quantity and quality in these samples. High quality DNA libraries are needed for optimal results from next-generation sequencing. Environmental samples such as water may have low quality and quantities of DNA as well as contaminants that co-precipitate with DNA. The mechanical and enzymatic processes involved in extraction and library preparation may further damage the DNA. Gel size selection enables purification and recovery of DNA fragments of a defined size for sequencing applications. Nevertheless, this task is one of the most time-consuming steps in the DNA library preparation workflow. The protocol described here enables complete automation of agarose gel loading, electrophoretic analysis, and recovery of targeted DNA fragments. 
In this study, we describe a high-throughput approach to prepare high quality DNA libraries from freshwater samples that can be applied also to other environmental samples. We used an indirect approach to concentrate bacterial cells from environmental freshwater samples; DNA was extracted using a commercially available DNA extraction kit, and DNA libraries were prepared using a commercial transposon-based protocol. DNA fragments of 500 to 800 bp were gel size selected using Ranger Technology, an automated electrophoresis workstation. Sequencing of the size-selected DNA libraries demonstrated significant improvements to read length and quality of the sequencing reads.

This manuscript describes an automated gel size selection approach for purifying DNA fragments for next-generation sequencing. The Ranger Technology provides complete automation of the entire process of agarose gel loading, electrophoretic analysis, and recovery of targeted DNA fragments allowing for high-throughput and high quality next-generation sequencing libraries.

Next-generation sequencing of environmental samples can be challenging because of the variable DNA quantity and quality in these samples. High quality DNA ...

Environment

Retrospective MicroRNA Sequencing: Complementary DNA Library Preparation Protocol Using Formalin-fixed Paraffin-embedded RNA Specimens

&#8211;Archived, clinically classified formalin-fixed paraffin-embedded (FFPE) tissues can provide nucleic acids for retrospective molecular studies of cancer development. By using non-invasive or pre-malignant lesions from patients who later develop invasive disease, gene expression analyses may help identify early molecular alterations that predispose to cancer risk. It has been well described that nucleic acids recovered from FFPE tissues have undergone severe physical damage and chemical modifications, which make their analysis difficult and generally requires adapted assays. MicroRNAs (miRNAs), however, which represent a small class of RNA molecules spanning only up to ~18&#8211;24 nucleotides, have been shown to withstand long-term storage and have been successfully analyzed in FFPE samples. Here we present a 3&#39; barcoded complementary DNA (cDNA) library preparation protocol specifically optimized for the analysis of small RNAs extracted from archived tissues, which was recently demonstrated to be robust and highly reproducible when using archived clinical specimens stored for up to 35 years. This library preparation is well adapted to the multiplex analysis of compromised/degraded material where RNA samples (up to 18) are ligated with individual 3&#39; barcoded adapters and then pooled together for subsequent enzymatic and biochemical preparations prior to analysis. All purifications are performed by polyacrylamide gel electrophoresis (PAGE), which allows size-specific selections and enrichments of barcoded small RNA species. This cDNA library preparation is well adapted to minute RNA inputs, as a pilot polymerase chain reaction (PCR) allows determination of a specific amplification cycle to produce optimal amounts of material for next-generation sequencing (NGS). This approach was optimized for the use of degraded FFPE RNA from specimens archived for up to 35 years and provides highly reproducible NGS data.

Formalin-fixed paraffin-embedded specimens represent a valuable source of molecular biomarkers of human diseases. Here we present a laboratory-based cDNA library preparation protocol, initially designed with fresh frozen RNA, and optimized for the analysis of archived microRNAs from tissues stored up to 35 years.

&#8211;Archived, clinically classified formalin-fixed paraffin-embedded (FFPE) tissues can provide nucleic acids for retrospective molecular studies of ...

Genetics

Mapping R-Loops and RNA:DNA Hybrids with S9.6-Based Immunoprecipitation Methods

R-loops constitute a prevalent class of transcription-driven non-B DNA structures that occur in all genomes depending on both DNA sequence and topological favorability. In recent years, R-loops have been implicated in a variety of adaptive and maladaptive roles and have been linked to genomic instability in the context of human disorders. As a consequence, the accurate mapping of these structures in genomes is of high interest to many investigators. DRIP-seq (DNA:RNA Immunoprecipitation followed by high throughput sequencing) is described here. It is a robust and reproducible technique that permits accurate and semi-quantitative mapping of R-loops. A recent iteration of the method is also described in which fragmentation is accomplished using sonication (sDRIP-seq), which allows strand-specific and high-resolution mapping of R-loops. sDRIP-seq thus addresses some of the common limitations of the DRIP-seq method in terms of resolution and strandedness, making it a method of choice for R-loop mapping.

R-loops constitute a prevalent class of transcription-driven non-B DNA structures that occur in all genomes depending on both DNA sequence and topological ...

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 ...

RIBO-seq in Bacteria: a Sample Collection and Library Preparation Protocol for NGS Sequencing

The ribosome profiling technique (RIBO-seq) is currently the most effective tool for studying the process of protein synthesis in vivo. The advantage of this method, in comparison to other approaches, is its ability to monitor translation by precisely mapping the position and number of ribosomes on a mRNA transcript.
In this article, we describe the consecutive stages of sample collection and preparation for RIBO-seq method in bacteria, highlighting the details relevant to the planning and execution of the experiment.
Since the RIBO-seq relies on intact ribosomes and related mRNAs, the key step is rapid inhibition of translation and adequate disintegration of cells. Thus, we suggest filtration and flash-freezing in liquid nitrogen for cell harvesting with an optional pretreatment with chloramphenicol to arrest translation in bacteria. For the disintegration, we propose grinding frozen cells with mortar and pestle in the presence of aluminum oxide to mechanically disrupt the cell wall. In this protocol, sucrose cushion or a sucrose gradient ultracentrifugation for monosome purification is not required. Instead, mRNA separation using polyacrylamide gel electrophoresis (PAGE) followed by the ribosomal footprint excision (28-30 nt band) is applied and provides satisfactory results. This largely simplifies the method as well as reduces the time and equipment requirements for the procedure. For library preparation, we recommend using the commercially available small RNA kit for Illumina sequencing from New England Biolabs, following manufacturer&#39;s guidelines with some degree of optimization.
The resulting cDNA libraries present appropriate quantity and quality required for next generation sequencing (NGS). Sequencing of the libraries prepared according to the described protocol results in 2 to 10 mln uniquely mapped reads per sample providing sufficient data for comprehensive bioinformatic analysis. The protocol we present is quick and relatively easy and can be performed with standard laboratory equipment.

Here we describe the stages of sample collection and preparation for RIBO-seq in bacteria. Sequencing of the libraries prepared according to these guidelines results in sufficient data for comprehensive bioinformatic analysis. The protocol we present is simple, uses standard laboratory equipment and takes seven days from lysis to obtaining libraries.

The ribosome profiling technique (RIBO-seq) is currently the most effective tool for studying the process of protein synthesis in vivo. The advantage of ...

Biochemistry

An Ultrahigh-throughput Microfluidic Platform for Single-cell Genome Sequencing

Sequencing technologies have undergone a paradigm shift from bulk to single-cell resolution in response to an evolving understanding of the role of cellular heterogeneity in biological systems. However, single-cell sequencing of large populations has been hampered by limitations in processing genomes for sequencing. In this paper, we describe a method for single-cell genome sequencing (SiC-seq) which uses droplet microfluidics to isolate, amplify, and barcode the genomes of single cells. Cell encapsulation in microgels allows the compartmentalized purification and tagmentation of DNA, while a microfluidic merger efficiently pairs each genome with a unique single-cell oligonucleotide barcode, allowing &gt;50,000 single cells to be sequenced per run. The sequencing data is demultiplexed by barcode, generating groups of reads originating from single cells. As a high-throughput and low-bias method of single-cell sequencing, SiC-seq will enable a broader range of genomic studies targeted at diverse cell populations.

Single-cell sequencing reveals genotypic heterogeneity in biological systems, but current technologies lack the throughput necessary for the deep profiling of community composition and function. Here, we describe a microfluidic workflow for sequencing &gt;50,000 single-cell genomes from diverse cell populations.

Sequencing technologies have undergone a paradigm shift from bulk to single-cell resolution in response to an evolving understanding of the role of ...

Ultra-long Read Sequencing for Whole Genomic DNA Analysis

Third generation single-molecule DNA sequencing technologies offer significantly longer read length that can facilitate the assembly of complex genomes and analysis of complex structural variants. Nanopore platforms perform single-molecule sequencing by directly measuring the current changes mediated by DNA passage through the pores and can generate hundreds of kilobase (kb) reads with minimal capital cost. This platform has been adopted by many researchers for a variety of applications. Achieving longer sequencing read lengths is the most critical factor to leverage the value of nanopore sequencing platforms. To generate ultra-long reads, special consideration is required to avoid DNA breakages and gain efficiency to generate productive sequencing templates. Here, we provide the detailed protocol of ultra-long DNA sequencing including high molecular weight (HMW) DNA extraction from fresh or frozen cells, library construction by mechanical shearing or transposase fragmentation, and sequencing on a nanopore device. From 20-25 &#181;g of HMW DNA, the method can achieve N50 read length of 50-70 kb with mechanical shearing and N50 of 90-100 kb read length with transposase mediated fragmentation. The protocol can be applied to DNA extracted from mammalian cells to perform whole genome sequencing for the detection of structural variants and genome assembly. Additional improvements on the DNA extraction and enzymatic reactions will further increase the read length and expand its utility.

Long-read sequences greatly facilitate the assembly of complex genomes and characterization of structural variation. We describe a method to generate ultra-long sequences by nanopore-based sequencing platforms. The approach adopts an optimized DNA extraction followed by modified library preparations to generate hundreds of kilobase reads with moderate coverage from human cells.

Third generation single-molecule DNA sequencing technologies offer significantly longer read length that can facilitate the assembly of complex genomes ...

High Throughput Yeast Strain Phenotyping with Droplet-Based RNA Sequencing

The powerful tools available to edit yeast genomes have made this microbe a valuable platform for engineering. While it is now possible to construct libraries of millions of genetically distinct strains, screening for a desired phenotype remains a significant obstacle. With existing screening techniques, there is a tradeoff between information output and throughput, with high-throughput screening typically being performed on one product of interest. Therefore, we present an approach to accelerate strain screening by adapting single cell RNA sequencing to isogenic picoliter colonies of genetically engineered yeast strains. To address the unique challenges of performing RNA sequencing on yeast cells, we culture isogenic yeast colonies within hydrogels and spheroplast prior to performing RNA sequencing. The RNA sequencing data can be used to infer yeast phenotypes and sort out engineered pathways. The scalability of our method addresses a critical obstruction in microbial engineering.

A bottleneck in the &#8216;design-build-test&#8217; cycle of microbial engineering is the speed at which we can perform functional screens of strains. We describe a high-throughput method for strain screening applied to hundreds to thousands of yeast cells per experiment that utilizes droplet-based RNA sequencing.

The powerful tools available to edit yeast genomes have made this microbe a valuable platform for engineering. While it is now possible to construct ...

Targeted RNA Sequencing Assay to Characterize Gene Expression and Genomic Alterations

RNA sequencing (RNAseq) is a versatile method that can be utilized to detect and characterize gene expression, mutations, gene fusions, and noncoding RNAs. Standard RNAseq requires 30 - 100 million sequencing reads and can include multiple RNA products such as mRNA and noncoding RNAs. We demonstrate how targeted RNAseq (capture) permits a focused study on selected RNA products using a desktop sequencer. RNAseq capture can characterize unannotated, low, or transiently expressed transcripts that may otherwise be missed using traditional RNAseq methods. Here we describe the extraction of RNA from cell lines, ribosomal RNA depletion, cDNA synthesis, preparation of barcoded libraries, hybridization and capture of targeted transcripts and multiplex sequencing on a desktop sequencer. We also outline the computational analysis pipeline, which includes quality control assessment, alignment, fusion detection, gene expression quantification and identification of single nucleotide variants. This assay allows for targeted transcript sequencing to characterize gene expression, gene fusions, and mutations.

We describe a targeted RNA sequencing-based method that includes preparation of indexed cDNA libraries, hybridization and capture with custom probes and data analysis to interrogate selected transcripts for gene expression, mutations, and gene fusions. Targeted RNAseq permits cost-effective, rapid evaluation of selected transcripts on a desktop sequencer.

RNA sequencing (RNAseq) is a versatile method that can be utilized to detect and characterize gene expression, mutations, gene fusions, and noncoding ...

Biology

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 ...