Name: pre-implantation genetic testing for aneuploidy on a semiconductor based next-generation sequencing platform
Uploaded: 2022-08-17T12:50:00
Description: Watch this Scientific Journal Video about Pre-Implantation Genetic Testing for Aneuploidy on a Semiconductor Based Next-Generation Sequencing Platform at JoVE.com

We would like to thank Dr. Zhangyong Ming and Mr. Rongji Hou for their advice on LIMS expanded application. This study is supported by PLA Special Research Projects for Family Planning (17JS008, 20JSZ08), Fund of Guangxi Key Laboratory of Metabolic Diseases Research (No.20-065-76), and Guangzhou Citizen Health Science and Technology Research Project (201803010034).

All protocols and the trophectoderm (TE) biopsy (1.1.1.1 section) applied in this study were reviewed and approved by the human research ethics committee of No. 924 hospital on September 18th, 2017 (NO: PLA924-2017-59). The patients/participants provided their written informed consent to participate in this study.
1. DNA isolation from human embryo biopsy and whole genomic amplification
<ol>
	<li>Protocol for whole genome amplification9,<su...

<ol>
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Chromosomal aneuploidy of embryos is the cause of a large proportion of pregnancy loss, whether conceived naturally or in vitro fertilization (IVF). In the clinical practice of IVF, it is proposed that screening the embryo aneuploidy and transferring the euploidy embryo could improve the outcome of IVF. Fluorescence in situ hybridization is the earliest technique adopted for sex selection and PGT-A; however, this technique requires more technical expertise from laboratory personnel and is relatively lab...

Aneuploidy is the abnormality in the number of chromosomes by the presence of one or more extra chromosomes or the absence of one or more chromosomes. Embryos that carry some type of aneuploidy, such as the loss of one X chromosome (Turner syndrome), extra copies of autosomes, like trisomies of autosome 21 (Down syndrome), 13 (Patau syndrome), and 18 (Edwards syndrome), or extra sex chromosomes such as 47, XXY (Klinefelter syndrome) and 47, XXX (Triple X syndrome), can survive to term with birth defects1. Aneuploidy is the primary cause of first trimester miscarriages and in vitro fertilization (IVF) failure2. It is reported that the aneuploidy rate could range from 25.4%-84.5% through the different age layers of the natural cycle and medicated control group in IVF practice3.
Next-generation sequencing technology is becoming wildly applied in the determination of genetic information clinically; it provides practical access to genome sequence with efficiency and high throughput. Particularly, next-generation sequencing also revolutionized the diagnosis of disorders with genetic factors and tests for abnormity in the genome4. Using semiconductor sequencing technology to directly transfer chemical signals in sequencing bio-reaction into digital data, the semiconductor-based sequence system provides a direct, real-time detection to sequence data in 3-7 h5,6.
In an IVF procedure, pre-implantation genetic testing (PGT) investigates the genetic profile of the embryo before being transferred into the uterus to improve the IVF outcome and reduce the risk of genetic disorders in newborns1,7. In PGT combined with NGS techniques, genetic material extracted from less than 10 cells is amplified with whole genome amplification kits or an independently developed whole genome amplification reagent. This requires only one step in the amplification phase and does not require pre-amplification, to obtain whole-genome amplification products. Primers or panels for copy number variant and special gene loci sequencing are designed and applied in the library constructed.
A typical workflow of pre-implantation genetic testing-aneuploidy (PGT-A) in NGS involves serial procedures, and requires an intense workload of laboratory personnel8. Some misoperation caused procedure roll-back may lead to undesired loss of both time and resources of the lab. A concise and clear standard operating procedure (SOP) for PGS-NGS workflow is helpful; however, word-format protocols cannot present more detailed information on sample processing, device manipulation, and instruments' settings, which can be visualized in a video protocol. In this article, a validated workflow combined with a visualized demonstration of operating detail could offer more direct and intuitive referring protocols in PGT practice on a semiconductor sequencing platform.
The protocol here describes a method that supports batching up to 16 embryo biopsies in parallel. For larger batches, it is recommended to use a commercial kit-based protocol for semiconductor sequencing, such as Reproes-PGS.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>0.45 &#956;m Syringe Filter Unit</td>
			<td>Merkmillipore</td>
			<td>Millex-HV</td>
			<td></td>
		</tr>
		<tr>
			<td>1.5 mL DNA LoBind Tubes</td>
			<td>Eppendorf</td>
			<td>30108051</td>
			<td></td>
		</tr>
		<tr>
			<td>15 mL tubes</td>
			<td>Greiner Bio-One</td>
			<td>188261</td>
			<td></td>
		</tr>
		<tr>
			<td>2.0 mLDNA LoBind Tubes</td>
			<td>Eppendorf</td>
			<td>30108078</td>
			<td></td>
		</tr>
		<tr>
			<td>50 mL tubes</td>
			<td>Greiner Bio-One</td>
			<td>227261</td>
			<td></td>
		</tr>
		<tr>
			<td>5x Anstart Taq Buffer (Mg2+ Plus)</td>
			<td>FAPON</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>&#160;Anstart Tap DNA Polymerase</td>
			<td>FAPON</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>AMPure XP reagent (magnetic beads for dna binding)</td>
			<td>Beckman</td>
			<td>A63881</td>
			<td>https://www.beckman.com/reagents/genomic/cleanup-and-size-selection/pcr/a63881</td>
		</tr>
		<tr>
			<td>Cell Lysis buffer</td>
			<td>Southern Medical University</td>
			<td></td>
			<td>Cell lysis buffer containing 40 mM Tris (pH 8), 100 mM NaCl, 2 mM EDTA, 1 mM ethylene glycol tetraacetic acid (EGTA), 1% (v/v) Triton X-100, 5 mM sodium pyrophosphate, 2 mM &#946;-glycerophosphate, 0.1% SDS</td>
		</tr>
		<tr>
			<td>ClinVar</td>
			<td>NCBI</td>
			<td></td>
			<td>https://www.ncbi.nlm.nih.gov/clinvar/</td>
		</tr>
		<tr>
			<td>DNA elution buffer</td>
			<td>NEB</td>
			<td>T1016L</td>
			<td></td>
		</tr>
		<tr>
			<td>dNTP</td>
			<td>Vazyme</td>
			<td>P031-AA</td>
			<td></td>
		</tr>
		<tr>
			<td>DynaMag-2 Magnet</td>
			<td>Life Technologies</td>
			<td>12321D</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethyl alcohol</td>
			<td>Guangzhou Chemical Reagent Factory Thermo Fisher Scientific</td>
			<td></td>
			<td>http://www.chemicalreagent.com/</td>
		</tr>
		<tr>
			<td>Independently developed whole genome amplification reagents</td>
			<td>Southern Medical University</td>
			<td></td>
			<td>The reagents consist of the following components: 
			1. Cell Lysis 
			2. Amplification Pre-mixed solution 
			&#160;&#160;&#160; 1) Primer WGA-P2 (10 &#956;M) 
			&#160;&#160;&#160; 2) dNTP (10 mM) 
			&#160;&#160;&#160; 3) 5x Anstart Taq Buffer (Mg2+ Plus) 
			3. Amplification Enzyme 
			&#160;&#160;&#160; 1) Anstart Tap DNA Polymerase (5 U/&#956;L)</td>
		</tr>
		<tr>
			<td>Ion PI Hi-Q OT2 200 Kit</td>
			<td>Thermo Fisher Scientific</td>
			<td>A26434</td>
			<td>Kit mentioned in step 4.2.8</td>
		</tr>
		<tr>
			<td>Ion PI Hi-Q Sequencing 200 Kit&#160;&#160;</td>
			<td>Thermo Fisher Scientific</td>
			<td>A26433</td>
			<td></td>
		</tr>
		<tr>
			<td>Ion Proton System</td>
			<td>Life Technologies</td>
			<td>4476610</td>
			<td></td>
		</tr>
		<tr>
			<td>Ion Reporter Server System</td>
			<td>Life Technologies</td>
			<td>4487118</td>
			<td></td>
		</tr>
		<tr>
			<td>isopropanol</td>
			<td>Guangzhou Chemical Reagent Factory</td>
			<td></td>
			<td>http://www.chemicalreagent.com/</td>
		</tr>
		<tr>
			<td>Library Preparation Kit</td>
			<td>Daan Gene Co., Ltd</td>
			<td>114</td>
			<td>https://www.daangene.com/pt/certificate.html</td>
		</tr>
		<tr>
			<td>NaOH</td>
			<td>Sigma-Aldrich</td>
			<td>S5881-1KG</td>
			<td></td>
		</tr>
		<tr>
			<td>Nuclease-Free Water</td>
			<td>Life Technologies</td>
			<td>AM9932</td>
			<td></td>
		</tr>
		<tr>
			<td>Oligo WGA-P2</td>
			<td>Sangon Biotech</td>
			<td></td>
			<td>5&#39;-ATGGTAGTCCGACTCGAGNNNN 
			NNNNATGTGG-3&#39;</td>
		</tr>
		<tr>
			<td>OneTouch 2 System</td>
			<td>Life Technologies</td>
			<td>4474779</td>
			<td>&#160;Template amplification and enrichment system</td>
		</tr>
		<tr>
			<td>PCR tubes</td>
			<td>Axygen</td>
			<td>PCR-02D-C</td>
			<td></td>
		</tr>
		<tr>
			<td>PicoPLEX WGA Kit</td>
			<td>Takara Bio USA</td>
			<td>R300671</td>
			<td></td>
		</tr>
		<tr>
			<td>Pipette tips</td>
			<td>Quality Scientific Products</td>
			<td></td>
			<td>https://www.qsptips.com/products/standard_pipette_tips.aspx</td>
		</tr>
		<tr>
			<td>Portable Mini Centrifuge LX-300</td>
			<td>Qilinbeier</td>
			<td>E0122</td>
			<td></td>
		</tr>
		<tr>
			<td>Qubit 3.0 Fluorometer</td>
			<td>Life Technologies</td>
			<td>Q33216</td>
			<td>Fluorometer</td>
		</tr>
		<tr>
			<td>Qubit Assay Tubes</td>
			<td>Life Technologies</td>
			<td>Q32856</td>
			<td></td>
		</tr>
		<tr>
			<td>Qubit dsDNA HS Assay Kit</td>
			<td>Life Technologies</td>
			<td>Q32851</td>
			<td></td>
		</tr>
		<tr>
			<td>Sequencer server system</td>
			<td>Thermo Fisher Scientific</td>
			<td></td>
			<td>Torrent Suite Software</td>
		</tr>
		<tr>
			<td>Sequencing Reactions Universal Kit</td>
			<td>Daan Gene Co., Ltd</td>
			<td>113</td>
			<td>https://www.daangene.com/pt/certificate.html 
			This kit contains the following components: 
			1. Template Preparation Kit Set 
			 
			1.1 Template Preparation Kit: 
			Emulsion PCR buffer 
			Emulsion PCR enzyme mix 
			Template carrier solution 
			 
			1.2 Template Preparation solutions: 
			Template preparation reaction oil I 
			emulsifier breaking solution II 
			Template Preparation Reaction Oil II 
			Nuclease-free water 
			Tween solution 
			Demulsification solution I 
			Template washing solution 
			C1 bead washing solution 
			C1 bead resuspension solution 
			Template resuspension solution 
			 
			1.3 Template Preparation Materials: 
			Reagent tube I 
			connector 
			Collection tube 
			Reagent tube pipette I 
			Amplification plate 
			8 wells strip 
			Dedicated tips 
			Template preparation washing adapter 
			Template preparation filter 
			 
			2. Sequencing Kit Set 
			 
			2.1 Sequencing Kit: 
			dGTP 
			dCTP 
			dATP 
			dTTP 
			Sequencing enzyme solution 
			Sequencing primers 
			Quality control templates 
			 
			2.2&#160; Sequencing Solutions: 
			Sequencing solution II 
			Sequencing solution IIII 
			Annealing buffer 
			Loading buffer 
			Foaming agent 
			Chlorine tablets 
			C1 bead 
			 
			2.3 Sequencing Materials: 
			Reagent Tube II 
			Reagent tube cap 
			Reagent tube sipper&#160; II 
			Reagent bottle sipper 
			Reagent bottles 
			 
			3. Chip</td>
		</tr>
		<tr>
			<td>Sodium hydroxide solution</td>
			<td>Sigma</td>
			<td>72068-100ML</td>
			<td></td>
		</tr>
		<tr>
			<td>Thermal Cycler</td>
			<td>Life Technologies</td>
			<td>4375786</td>
			<td></td>
		</tr>
	</tbody>
</table>

pre-implantation genetic testing for aneuploidy on a semiconductor based next-generation sequencing platform

Next-generation sequencing has gained increasing importance in the clinical application in the determination of genetic variants. In the pre-implantation genetic test, this technique has its unique advantages in scalability, throughput, and cost. For the pre-implantation genetic test for aneuploidy analysis, the semiconductor-based next-generation sequencing (NGS) system presented here provides a comprehensive approach to determine structural genetic variants at a minimum resolution of 8 Mb. From sample acquisition to the final report, the working process requires multiple steps with close adherence to protocols. Since various critical steps could determine the outcome of amplification, quality of the library, coverage of reads, and output of data, descriptive information with visual demonstration other than words could offer more detail to the operation and manipulation, which may have a great impact on the results of all critical steps. The methods presented herein will display the procedures involved in whole genome amplification (WGA) of biopsied Trophectoderm (TE) cells, genomic library construction, sequencer management, and finally, generating copy number variants' reports.

As the sequences plan finishes after the running process in the machine, the sequence server system reports the summary with descriptive information of data generated, chip status, ISP loading rate, and library quality, as shown in Figure 2. In this results demonstration, 17.6 G data in the total base was obtained, and the overall loading rate of ISP was 88% in the total wells of the chip; the heat map showed that the sample was evenly loaded on the total area of the chip (<strong class="xfi...

Watch this Scientific Journal Video about Pre-Implantation Genetic Testing for Aneuploidy on a Semiconductor Based Next-Generation Sequencing Platform at JoVE.com

Pre-Implantation Genetic Testing for Aneuploidy on a Semiconductor Based Next-Generation Sequencing Platform

The protocol presents the overall in-lab procedures required in pre-implantation genetic testing for aneuploidy on a semiconductor-based next-generation sequencing platform. Here we present the detailed steps of whole genome amplification, DNA fragment selection, library construction, template preparation, and sequencing working flow with representative results.

Next-generation sequencing has gained increasing importance in the clinical application in the determination of genetic variants. In the pre-implantation ...

This protocol presents the procedure from single cell amplification to final reporting data in the pre-implantation genetic testing for aneuploidy on a semiconductor based next generation sequencing platform. This procedure can help viewers have a good understanding of the experimental workflow of PGT-A sequencing and replicate this technique in a diagnostic laboratory with a semiconductor based NGS platform. Begin by pipetting 25 microliters of the whole genome amplification products and transferring them into a 1.5 milliliter centrifuge tube preloaded with 25 microliters of nuclease free water.Vortex and mix the DNA purification beads. Aliquot 50 microliters of this solution into each sample tube. Vortex and centrifuge briefly for five seconds.Set the tube for five minutes at room temperature for the DNA binding process. Insert the 1.5 milliliter centrifuge tube into a magnetic rack. Then, wait till all the magnetic beads are attracted to the side wall of the tube.Carefully transfer the supernatant into a new 1.5 milliliter centrifuge tube. Avoid pipetting out the beads. According to the original sample volume.Pipette 30 microliters of magnetic beads, vortex and centrifuge briefly for five seconds. Set the tube for five minutes at room temperature for the DNA binding process. Insert the 1.5 millimeter centrifuge tubes into the magnetic rack.Then, wait until all the magnetic beads are attracted to the side wall of the tube. Carefully remove and discard the supernatant. Avoid pipetting the beads out.Pipette 300 microliters of 70%ethanol into the 1.5 milliliter centrifuge tube. Then gently rotate the tube twice at a 180-degree angle and move the beads along the tube wall for a thorough wash. Pipette and discard the supernatant.Avoid pipetting the beads out. Repeat the wash procedure once. Place a new amplification plate in the system once the clean program is completed.Insert the collection tubes, each prefilled with 150 microliters breaking solution two into the rotor, then place the bridge on the collection tubes. Add the reaction oil to half of the tube and the emulsifier breaking solution to one third of the tube. Place a new filter for template preparation on a tube rack with the sample portal positioned upwards.Vortex the solution for five seconds and centrifuge briefly for five seconds. Then transfer the solution into the sample portal of the filter after pipetting 800 microliters three times. Centrifuge the tube to decrease bubbles before the last injection.Avoid injecting air into the filter. Inject 200 microliters of reaction oil two, following the mixed solution. Turn the sample portal of the filter downwards and replace the washing adapt with the filter.Insert the sample needle into the center hole of the rotor lid and then press the needle to the bottom. Click on the Run button on the screen and choose the program according to the corresponding kit. Then select Assisted to check all steps.Click on Next till the run is started. The run will take approximately 4.5 hours to finish. Select Next when the program finishes.The system will start a 10-minute centrifugation process. After centrifugation, click the Open Lid button and move the collection tubes to racks. If the procedure does not move to the next step in 15 minutes, press on final spin to re-centrifuge.Remove the supernatant in the collection tube, leaving 100 microliters of solution in the tube. Mix the remaining sample by pipetting and transfer the sample to the new 1.5 milliliter centrifuge tube marked OT.When pipetting the supernatant, avoid touching the bottom of the tube along the sides. Pipette 100 microliters of nuclease free water into each collection tube and transfer the solution to the OT tube washed by repeated pipetting.Add 600 microliters of nuclease free water to the OT tube to make up the total volume of one milliliter. Vortex for 30 seconds in centrifuge at 15, 500 times G for eight minutes. Gently remove the supernatant leaving 100 microliters of solution in the OT tube.Use the tip to discard the oil layer completely. Add 900 microliters of nuclease free water, vortex for 30 seconds and centrifuge at 15, 500 times G for eight minutes. Remove the supernatant until 20 microliters of the solution remains and add the template resuspending solution to make up the volume of 100 microliters.Then vortex for 30 seconds and briefly centrifuge for two seconds. Proceed to the next step within 12 hours of sample processing Load 100 microliters of the diluted library, 130 microliters of C1 beads, 300 microliters of three x template washing solution, and 300 microliters of the melt off solution to the eight well strips. Install the eight well strips on the Enrichment Module, load the pipetting tip, and set the 200 microliters centrifuge tube in the collection position.Click on Start to run the program. Pipette 55 microliters of the sample solution and inject it into the sample hole of the chip. Set the chip on the centrifuge.Keep the notch towards the outside and the sample portal inside. Then, balance it with another used chip and centrifuge for 10 minutes. Prepare the loading solution as described in the text manuscript.Blow 100 microliters of air into the foaming solution. Pipette the solution repeatedly till the bubbles are in a dense, foaming state and keep the foam volume to approximately 250 microliters. Place the chip on the bench after centrifuge.Inject 100 microliters of foam into the sample hole and remove the extruded solution into the out portal. Then, centrifuge the chip briefly for 30 seconds. Repeat this process once.Inject 100 microliters at 50%washing buffer twice and remove the extruded solution in the out portal after every injection. Then inject 100 microliters at 50%annealing buffer three times and remove the extruded solution in the out portal after every injection. Inject 65 microliters at 50%enzyme reaction buffer, avoiding bubbles and remove the extruded solution in the out portal.Stabilize the loaded chip at room temperature for five minutes and install the chip on the sequencer chip portal. Choose the Planned program check the information and start the run. The representative run obtained a total of 17.6 gigabyte data and the overall loading rate of the ion sphere particle was 88%in the total wells of the chip.The heat map confirmed even sample loading on the total chip area. 77%of the total reads were usable. All wells loaded with ISP showed 100%templates enrichment in which 78%were clonal.Out of all clonal templates 97%were qualified as the final library. The average length of the read was 177 base pairs while the median and mode were 176 and 174 base pairs, respectively. Peak counts of thymine, cytosine and adenine in the templates were approximately 76 over the qualified cutoff line of 50.In all addressable wells with live ISPs 99.5%qualified as the constructed library and 20%of polyclonal and low quality libraries were filtered out while 76.6%of ISPs were qualified for further analysis. The result of copy number variance from a single sample depicted a 182.16 megabase pairs mosaic trisomy of P 16.3 to Q 35.2 on chromosome four and a 33 point 13 megabase pairs monosomy segment of Q 11.1 to Q 13.33 on Chromosome 22. When performing fragment selection, time intervals between steps should be modified according to the size of samples in the same batch to prevent over and lack of exposure for front and rear end samples.

pre-implantation-genetic-testing-for-aneuploidy-on-semiconductor

Research

JoVE Journal

Genetics

Assessment of DNA Contamination in RNA Samples Based on Ribosomal DNA

One method extensively used for the quantification of gene expression changes and transcript abundances is reverse-transcription quantitative real-time PCR (RT-qPCR). It provides accurate, sensitive, reliable, and reproducible results. Several factors can affect the sensitivity and specificity of RT-qPCR. Residual genomic DNA (gDNA) contaminating RNA samples is one of them. In gene expression analysis, non-specific amplification due to gDNA contamination will overestimate the abundance of transcript levels and can affect the RT-qPCR results. Generally, gDNA is detected by qRT-PCR using primer pairs annealing to intergenic regions or an intron of the gene of interest. Unfortunately, intron/exon annotations are not yet known for all genes from vertebrate, bacteria, protist, fungi, plant, and invertebrate metazoan species.
Here we present a protocol for detection of gDNA contamination in RNA samples by using ribosomal DNA (rDNA)-based primers. The method is based on the unique features of rDNA: their multigene nature, highly conserved sequences, and high frequency in the genome. Also as a case study, a unique set of primers were designed based on the conserved region of ribosomal DNA (rDNA) in the Poaceae family. The universality of these primer pairs was tested by melt curve analysis and agarose gel electrophoresis. Although our method explains how rDNA-based primers can be applied for the gDNA contamination assay in the Poaceae family,&#160;it could be easily used to other prokaryote and eukaryote species

Here, we present a protocol for tracing genomic DNA (gDNA) contamination in RNA samples. The presented method utilizes primers specific for the internal transcribed spacer region (ITS) of ribosomal DNA (rDNA) genes. The method is suited for reliable and sensitive detection of DNA contamination in most eukaryotes and prokaryotes.

One method extensively used for the quantification of gene expression changes and transcript abundances is reverse-transcription quantitative real-time ...

Optimization and Comparative Analysis of Plant Organellar DNA Enrichment Methods Suitable for Next-generation Sequencing

Plant organellar genomes contain large, repetitive elements that may undergo pairing or recombination to form complex structures and/or sub-genomic fragments. Organellar genomes also exist in admixtures within a given cell or tissue type (heteroplasmy), and an abundance of subtypes may change throughout development or when under stress (sub-stoichiometric shifting). Next-generation sequencing (NGS) technologies are required to obtain deeper understanding of organellar genome structure and function. Traditional sequencing studies use several methods to obtain organellar DNA: (1) If a large amount of starting tissue is used, it is homogenized and subjected to differential centrifugation and/or gradient purification. (2) If a smaller amount of tissue is used (i.e., if seeds, material, or space is limited), the same process is performed as in (1), followed by whole-genome amplification to obtain sufficient DNA. (3) Bioinformatics analysis can be used to sequence the total genomic DNA and to parse out organellar reads. All these methods have inherent challenges and tradeoffs. In (1), it may be difficult to obtain such a large amount of starting tissue; in (2), whole-genome amplification could introduce a sequencing bias; and in (3), homology between nuclear and organellar genomes could interfere with assembly and analysis. In plants with large nuclear genomes, it is advantageous to enrich for organellar DNA to reduce sequencing costs and sequence complexity for bioinformatics analyses. Here, we compare a traditional differential centrifugation method with a fourth method, an adapted CpG-methyl pulldown approach, to separate the total genomic DNA into nuclear and organellar fractions. Both methods yield sufficient DNA for NGS, DNA that is highly enriched for organellar sequences, albeit at different ratios in mitochondria and chloroplasts. We present the optimization of these methods for wheat leaf tissue and discuss major advantages and disadvantages of each approach in the context of sample input, protocol ease, and downstream application.

The comparison and optimization of two plant organellar DNA enrichment methods are presented: traditional differential centrifugation and fractionation of the total gDNA based on methylation status. We assess the resulting DNA quantity and quality, demonstrate performance in short-read next-generation sequencing, and discuss the potential for use in long-read single-molecule sequencing.

Plant organellar genomes contain large, repetitive elements that may undergo pairing or recombination to form complex structures and/or sub-genomic ...

G2-seq: A High Throughput Sequencing-based Technique for Identifying Late Replicating Regions of the Genome

Numerous techniques have been developed to follow the progress of DNA replication through the S phase of the cell cycle. Most of these techniques have been directed toward elucidation of the location and timing of initiation of genome duplication rather than its completion. However, it is critical that we understand regions of the genome that are last to complete replication, because these regions suffer elevated levels of chromosomal breakage and mutation, and they have been associated with both disease and aging. Here we describe how we have extended a technique that has been used to monitor replication initiation to instead identify those regions of the genome last to complete replication. This approach is based on a combination of flow cytometry and high throughput sequencing. Although this report focuses on the application of this technique to yeast, the approach can be used with any cells that can be sorted in a flow cytometer according to DNA content.

We describe a technique for combining flow cytometry and high throughput sequencing to identify late replicating regions of the genome.

Numerous techniques have been developed to follow the progress of DNA replication through the S phase of the cell cycle. Most of these techniques have ...

Targeted Next-generation Sequencing and Bioinformatics Pipeline to Evaluate Genetic Determinants of Constitutional Disease

Next-generation sequencing (NGS) is quickly revolutionizing how research into the genetic determinants of constitutional disease is performed. The technique is highly efficient with millions of sequencing reads being produced in a short time span and at relatively low cost. Specifically, targeted NGS is able to focus investigations to genomic regions of particular interest based on the disease of study. Not only does this further reduce costs and increase the speed of the process, but it lessens the computational burden that often accompanies NGS. Although targeted NGS is restricted to certain regions of the genome, preventing identification of potential novel loci of interest, it can be an excellent technique when faced with a phenotypically and genetically heterogeneous disease, for which there are previously known genetic associations. Because of the complex nature of the sequencing technique, it is important to closely adhere to protocols and methodologies in order to achieve sequencing reads of high coverage and quality. Further, once sequencing reads are obtained, a sophisticated bioinformatics workflow is utilized to accurately map reads to a reference genome, to call variants, and to ensure the variants pass quality metrics. Variants must also be annotated and curated based on their clinical significance, which can be standardized by applying the American College of Medical Genetics and Genomics Pathogenicity Guidelines. The methods presented herein will display the steps involved in generating and analyzing NGS data from a targeted sequencing panel, using the ONDRISeq neurodegenerative disease panel as a model, to identify variants that may be of clinical significance.

Targeted next-generation sequencing is a time- and cost-efficient approach that is becoming increasingly popular in both disease research and clinical diagnostics. The protocol described here presents the complex workflow required for sequencing and the bioinformatics process used to identify genetic variants that contribute to disease.

Next-generation sequencing (NGS) is quickly revolutionizing how research into the genetic determinants of constitutional disease is performed. The ...

Amplification of Near Full-length HIV-1 Proviruses for Next-Generation Sequencing

The Full-Length Individual Proviral Sequencing (FLIPS) assay is an efficient and high-throughput method designed to amplify and sequence single, near full-length (intact and defective), HIV-1 proviruses. FLIPS allows determination of the genetic composition of integrated HIV-1 within a cell population. Through identifying defects within HIV-1 proviral sequences that arise during reverse transcription, such as large internal deletions, deleterious stop codons/hypermutation, frameshift mutations, and mutations/deletions in cis acting elements required for virion maturation, FLIPS can identify integrated proviruses incapable of replication. The FLIPS assay can be utilized to identify HIV-1 proviruses that lack these defects and are&#160;therefore potentially replication-competent. The FLIPS protocol involves: lysis of HIV-1 infected cells, nested PCR of near full-length HIV-1 proviruses (using primers targeted to the HIV-1 5&#39; and 3&#39; LTR), DNA purification and quantification, library preparation for Next-generation Sequencing (NGS), NGS, de novo assembly of proviral contigs, and a simple process of elimination for identifying replication-competent proviruses. FLIPS provides advantages over traditional methods designed to sequence integrated HIV-1 proviruses, such as single-proviral sequencing. FLIPS amplifies and sequences near full-length proviruses enabling replication competency to be determined, and also uses fewer amplification primers, preventing the consequences of primer mismatches. FLIPS is a useful tool for understanding the genetic landscape of integrated HIV-1 proviruses, especially within the latent reservoir, however, its utilization can extend to any application in which the genetic composition of integrated HIV-1 is required.

Full-length individual proviral sequencing (FLIPS) provides an efficient and high-throughput method for the amplification and sequencing of single, near full-length (intact and defective) HIV-1 proviruses and allows for determination of their potential replication-competency. FLIPS overcomes limitations of previous assays designed to sequence the latent HIV-1 reservoir.

The Full-Length Individual Proviral Sequencing (FLIPS) assay is an efficient and high-throughput method designed to amplify and sequence single, near ...

High-throughput Identification of Gene Regulatory Sequences Using Next-generation Sequencing of Circular Chromosome Conformation Capture (4C-seq)

The identification of regulatory elements for a given target gene poses a significant technical challenge owing to the variability in the positioning and effect sizes of regulatory elements to a target gene. Some progress has been made with the bioinformatic prediction of the existence and function of proximal epigenetic modifications associated with activated gene expression using conserved transcription factor binding sites. Chromatin conformation capture studies have revolutionized our ability to discover physical chromatin contacts between sequences and even within an entire genome. Circular chromatin conformation capture coupled with next-generation sequencing (4C-seq), in particular, is designed to discover all possible physical chromatin interactions for a given sequence of interest (viewpoint), such as a target gene or a regulatory enhancer. Current 4C-seq strategies directly sequence from within the viewpoint but require numerous and diverse viewpoints to be simultaneously sequenced to avoid the technical challenges of uniform base calling (imaging) with next generation sequencing platforms. This volume of experiments may not be practical for many laboratories. Here, we report a modified approach to the 4C-seq protocol that incorporates both an additional restriction enzyme digest and qPCR-based amplification steps that are designed to facilitate a greater capture of diverse sequence reads and mitigate the potential for PCR bias, respectively. Our modified 4C method is amenable to the standard molecular biology lab for assessing chromatin architecture.

High-throughput Identification of Gene Regulatory Sequences Using Next-generation Sequencing of Circular Chromosome Conformation Capture 4C-seq

The identification of physical interactions between genes and regulatory elements is challenging but has been facilitated by chromosome conformation capture methods. This modification to the 4C-seq protocol mitigates PCR bias by minimizing over-amplification of PCR templates and maximizes the mappability of reads by incorporating an addition restriction enzyme digest step.

The identification of regulatory elements for a given target gene poses a significant technical challenge owing to the variability in the positioning and ...

Genetic Engineering of Dictyostelium discoideum Cells Based on Selection and Growth on Bacteria

Dictyostelium discoideum is an intriguing model organism for the study of cell differentiation processes during development, cell signaling, and other important cellular biology questions. The technologies available to genetically manipulate Dictyostelium cells are well-developed. Transfections can be performed using different selectable markers and marker re-cycling, including homologous recombination and insertional mutagenesis. This is supported by a well-annotated genome. However, these approaches are optimized for axenic cell lines growing in liquid cultures and are difficult to apply to non-axenic wild-type cells, which feed only on bacteria. The mutations that are present in axenic strains disturb Ras signaling, causing excessive macropinocytosis required for feeding, and impair cell migration, which confounds the interpretation of signal transduction and chemotaxis experiments in those strains. Earlier attempts to genetically manipulate non-axenic cells have lacked efficiency and required complex experimental procedures. We have developed a simple transfection protocol that, for the first time, overcomes these limitations. Those series of large improvements to Dictyostelium molecular genetics allow wild-type cells to be manipulated as easily as standard laboratory strains. In addition to the advantages for studying uncorrupted signaling and motility processes, mutants that disrupt macropinocytosis-based growth can now be readily isolated. Furthermore, the entire transfection workflow is greatly accelerated, with recombinant cells that can be generated in days rather than weeks. Another advantage is that molecular genetics can further be performed with freshly isolated wild-type Dictyostelium samples from the environment. This can help to extend the scope of approaches used in these research areas.

Genetic Engineering of Dictyostelium discoideum Cells Based on Selection and Growth on Bacteria

Dictyostelium discoideum is a popular model organism to study complex cellular processes such as cell migration, endocytosis, and development. The utility of the organism is dependent on the feasibility of genetic manipulation. Here, we present methods to transfect Dictyostelium discoideum cells that overcome existing limitations of culturing cells in liquid media.

Dictyostelium discoideum is an intriguing model organism for the study of cell differentiation processes during development, cell signaling, and other ...

Semiconductor Sequencing for Preimplantation Genetic Testing for Aneuploidy

Chromosomal aneuploidy, one of the main causes leading to embryonic development arrest, implantation failure, or pregnancy loss, has been well documented in human embryos. Preimplantation genetic testing for aneuploidy (PGT-A) is a genetic test that significantly improves reproductive outcomes by detecting chromosomal abnormalities of embryos. Next-generation sequencing (NGS) provides a high-throughput and cost-effective approach for genetic analysis and has shown clinical applicability in PGT-A. Here, we present a rapid and low-cost semiconductor sequencing-based NGS method for screening of aneuploidy in embryos. The first step of the workflow is whole genome amplification (WGA) of the biopsied embryo specimen, followed by construction of sequencing library, and subsequent sequencing on the semiconductor sequencing system. Generally, for a PGT-A application, 24 samples can be loaded and sequenced on each chip generating 60&#8722;80 million reads at an average read length of 150 base pairs. The method provides a refined protocol for performing template amplification and enrichment of sequencing library, making the PGT-A detection reproducible, high-throughput, cost-efficient, and timesaving. The running time of this semiconductor sequencer is only 2&#8722;4 hours, shortening the turnaround time from receiving samples to issuing reports into 5 days. All these advantages make this assay an ideal method to detect chromosomal aneuploidies from embryos and thus, facilitate its wide application in PGT-A.

Here, we introduce a semiconductor sequencing method for preimplantation genetic testing for aneuploidy (PGT-A) with the advantages of short turnaround time, low cost, and high throughput.

Chromosomal aneuploidy, one of the main causes leading to embryonic development arrest, implantation failure, or pregnancy loss, has been well documented ...

Mass Spectrometry-Based Proteomics Analyses Using the OpenProt Database to Unveil Novel Proteins Translated from Non-Canonical Open Reading Frames

Genome annotation is central to today's proteomic research as it draws the outlines of the proteomic landscape. Traditional models of open reading frame (ORF) annotation impose two arbitrary criteria: a minimum length of 100 codons and a single ORF per transcript. However, a growing number of studies report expression of proteins from allegedly non-coding regions, challenging the accuracy of current genome annotations. These novel proteins were found encoded either within non-coding RNAs, 5' or 3' untranslated regions (UTRs) of mRNAs, or overlapping a known coding sequence (CDS) in an alternative ORF. OpenProt is the first database that enforces a polycistronic model for eukaryotic genomes, allowing annotation of multiple ORFs per transcript. OpenProt is freely accessible and offers custom downloads of protein sequences across 10 species. Using OpenProt database for proteomic experiments enables novel proteins discovery and highlights the polycistronic nature of eukaryotic genes. The size of OpenProt database (all predicted proteins) is substantial and need be taken in account for the analysis. However, with appropriate false discovery rate (FDR) settings or the use of a restricted OpenProt database, users will gain a more realistic view of the proteomic landscape. Overall, OpenProt is a freely available tool that will foster proteomic discoveries.

OpenProt is a freely accessible database that enforces a polycistronic model of eukaryotic genomes. Here, we present a protocol for the use of OpenProt databases when interrogating mass spectrometry datasets. Using OpenProt database for analysis of proteomic experiments allows for discovery of novel and previously undetectable proteins.

Genome annotation is central to today's proteomic research as it draws the outlines of the proteomic landscape. Traditional models of open reading frame ...

RNA Next-Generation Sequencing and a Bioinformatics Pipeline to Identify Expressed LINE-1s at the Locus-Specific Level

Long INterspersed Elements-1 (LINEs/L1s) are repetitive elements that can copy and randomly insert in the genome resulting in genomic instability and mutagenesis. Understanding the expression patterns of L1 loci at the individual level will lend to the understanding of the biology of this mutagenic element. This autonomous element makes up a significant portion of the human genome with over 500,000 copies, though 99% are truncated and defective. However, their abundance and dominant number of defective copies make it challenging to identify authentically expressed L1s from L1-related sequences expressed as part of other genes. It is also challenging to identify which specific L1 locus is expressed due to the repetitive nature of the elements. Overcoming these challenges, we present an RNA-Seq bioinformatic approach to identify L1 expression at the locus specific level. In summary, we collect cytoplasmic RNA, select for polyadenylated transcripts, and utilize strand-specific RNA-Seq analyses to uniquely map reads to L1 loci in the human reference genome. We visually curate each L1 locus with uniquely mapped reads to confirm transcription from its own promoter and adjust mapped transcript reads to account for mappability of each individual L1 locus. This approach was applied to a prostate tumor cell line, DU145, to demonstrate the ability of this protocol to detect expression from a small number of the full-length L1 elements.

Here, we present a bioinformatic approach and analyses to identify LINE-1 expression at the locus specific level.

Long INterspersed Elements-1 (LINEs/L1s) are repetitive elements that can copy and randomly insert in the genome resulting in genomic instability and ...