Name: dna extraction from 0.22 &mu;m sterivex filters and cesium chloride density gradient centrifugation
Uploaded: 2009-09-18T05:00:00
Description: Watch this Scientific Journal Video about DNA Extraction from 0.22 Î¼M Sterivex Filters and Cesium Chloride Density Gradient Centrifugation at JoVE.com

We would like to thank the Canadian Foundation for Innovation, the British Columbia Knowledge Development Fund and the National Sciences and Engineering Research Council (NSERC) of Canada for supporting ongoing studies on low oxygen regions of coastal and open ocean waters. J.J.W. was supported by fellowships from NSERC and D.A.W. was supported by fellowships from NSERC, Killam and the TULA foundation funded Centre for Microbial Diversity and Evolution. S.L. was supported by the TULA foundation funded Centre for Microbial Diversity and Evolution.

Note: All reagents used in this protocol are aliquoted from lab stocks into smaller working stocks- this is very important to avoid cross contamination of your DNA samples and contamination of lab stocks. Also, when pipetting, make sure to change pipette tips for every addition to avoid cross contamination.
Part One: Cell Lysis and Digestion
<ol>
<li>Begin this protocol by thawing the Sterivex filters that contain previously concentrated planktonic bioma...

<ol>
	<li>Beja, O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=To+BAC+or+not+to+BAC:+marine+ecogenomics.">To BAC or not to BAC: marine ecogenomics.</a> Curr Opin Biotechnol. 15 (3), 187-190 (2004).</li><li>Beja, O., Suzuki, M. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Construction+and+analysis+of+bacterial+artificial+chromosome+libraries+from+a+marine+microbial+assemblage.">Construction and analysis of bacterial artificial chromosome libraries from a marine microbial assemblage.</a> Environ Microbiol. 2 (5), 516-529 (2000).</li><li>DeLong, E. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Community+genomics+among+stratified+microbial+assemblages+in+the+oceans+interior.">Community genomics among stratified microbial assemblages in the oceans interior.</a> Science. 311, 496-503 (2006).</li><li>Stein, J. L., Marsh, T. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+of+uncultivated+prokaryotes:+isolation+and+analysis+of+a+40-kilobase-pair+genome+fragment+from+a+planktonic+marine+archaeon.">Characterization of uncultivated prokaryotes: isolation and analysis of a 40-kilobase-pair genome fragment from a planktonic marine archaeon.</a> J Bacteriol. 178 (3), 591-599 (1996).</li><li>Somerville, C. C., Knight, I. T., Straube, W. L., Colwell, R. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+simple,+rapid+method+for+the+direct+isolation+of+nucleic+acids+from+aquatic+environments.">A simple, rapid method for the direct isolation of nucleic acids from aquatic environments.</a> Appl. Environ. Microbiol. 55 (3), 548-554 (1989).</li></ol>

Depending on how many samples are to be processed, this can be a time-intensive procedure due to the two one-hour incubation steps, and the repeated washes and centrifugation steps. It is best to plan two whole days for this procedure to leave plenty of time. If there are problems getting the final extract volume in the Amicon tube to reduce down to 200-500&mu;l during DNA concentration and washing, try doing additional TE washes and centrifugations (repeat Part Three) until the appropriate volume is leftover. Also, i...

A correction was made to "<a href="/video/1352">DNA Extraction from 0.22 &#181;M Sterivex Filters and Cesium Chloride Density Gradient Centrifugation</a>". A typo in a volume's measurement was corrected in step 1.2.
The step was corrected from:
Once the filter has thawed, begin the first of two incubations: one to lyse the cells and remove RNA, and one to break down proteins. For the first incubation, add 100 &#956;l lysozyme (125 mg in 1000 &#956;l TE) and 20 ml RNase A (10 &#956;g/ml) to the filter. Reseal the filter with Parafilm and leave it to rotate in the hybridization oven at 37&#176;C for 1 hour.
to:
Once the filter has thawed, begin the first of two incubations: one to lyse the cells and remove RNA, and one to break down proteins. For the first incubation, add 100 &#956;l lysozyme (125 mg in 1000 &#956;l TE) and 20 &#956;l RNase A (10 &#956;g/ml) to the filter. Reseal the filter with Parafilm and leave it to rotate in the hybridization oven at 37&#176;C for 1 hour.

A correction was made to <a href="/video/1352">DNA Extraction from 0.22 &#181;M Sterivex Filters and Cesium Chloride Density Gradient Centrifugation</a>. A typo in a volume's measurement was corrected in step 1.2.

Erratum: DNA Extraction from 0.22 &#181;M Sterivex Filters and Cesium Chloride Density Gradient Centrifugation

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		<th>Material Name</th>
		<th>Type</th>
		<th>Company</th>
		<th>Catalogue Number</th>
		<th>Comment</th>
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<tr>
<td>1 cc syringe (26G5/8 needle)</td>
<td>&nbsp;</td>
<td>BD</td>
<td>309597</td>
<td>&nbsp;</td>
<tr>
<td>1 ml syringe (26G5/8 needle)</td>
<td>&nbsp;</td>
<td>BD</td>
<td>309597</td>
<td>&nbsp;</td>
<tr>
<td>1.5ml eppendorf tubes</td>
<td>&nbsp;</td>
<td>Eppendorf</td>
<td>0030 125.150</td>
<td>&nbsp;</td>
<tr>
<td>15ml tubes</td>
<td>&nbsp;</td>
<td>Sigma</td>
<td>CLS430791</td>
<td>&nbsp;</td>
<tr>
<td>5cc syringe</td>
<td>&nbsp;</td>
<td>BD</td>
<td>309603</td>
<td>&nbsp;</td>
<tr>
<td>Amicon&reg; Ultra-4 Centrifugal Filter Devices</td>
<td>&nbsp;</td>
<td>Millipore</td>
<td>UFC801096</td>
<td>10,000 Nominal molecular weight limit</td>
</tr>
<tr>
<td>Butanol</td>
<td>&nbsp;</td>
<td>Fisher</td>
<td>A383-1</td>
<td>Make it water saturated (butanol:water = 1:1)</td>
</tr>
<tr>
<td>Centrifuge rotor, JA5.3 </td>
<td>&nbsp;</td>
<td>Beckman Coulter</td>
<td>368690</td>
<td>&nbsp;</td>
<tr>
<td>Centrifuge, Avanti&reg; J-E</td>
<td>&nbsp;</td>
<td>Beckman Coulter</td>
<td>369003</td>
<td>&nbsp;</td>
<tr>
<td>Cesium chloride</td>
<td>&nbsp;</td>
<td>Sigma</td>
<td>C4036</td>
<td>&nbsp;</td>
<tr>
<td>Chloroform:IAA (24:1)</td>
<td>&nbsp;</td>
<td>Sigma</td>
<td>25666-500ML</td>
<td>&nbsp;</td>
<tr>
<td>Ethidium Bromide (EtBr)</td>
<td>&nbsp;</td>
<td>Sigma</td>
<td>E1510-10ml</td>
<td>&nbsp;</td>
<tr>
<td>Ethylenediaminetetraacetic acid disodium salt dihydrate</td>
<td>&nbsp;</td>
<td>Sigma</td>
<td>E5134</td>
<td>&nbsp;</td>
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<td>Hybridization oven</td>
<td>&nbsp;</td>
<td>Fisher Scientific</td>
<td>13-247-10</td>
<td>37&deg;C & 55&deg;C</td>
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<td>Lysis Buffer</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>0.75 M sucrose, 40 mM EDTA, 50 mM Tris (pH 8.3)</td>
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<tr>
<td>Lysozyme</td>
<td>&nbsp;</td>
<td>Sigma</td>
<td>L6876-5G</td>
<td>125 mg in 1000 &mu;l TE</td>
</tr>
<tr>
<td>Microcon&reg; Ultracel YM-30 Centrifugal Filter Unit</td>
<td>&nbsp;</td>
<td>Millipore</td>
<td>42410</td>
<td>50 bp cut off</td>
</tr>
<tr>
<td>Parafilm</td>
<td>&nbsp;</td>
<td>Fisher</td>
<td>13-374-10</td>
<td>&nbsp;</td>
<tr>
<td>Phenol:Chloroform:IAA (25:24:1)</td>
<td>&nbsp;</td>
<td>Sigma</td>
<td>77617-500ML</td>
<td>&nbsp;</td>
<tr>
<td>Proteinase K</td>
<td>&nbsp;</td>
<td>Qiagen</td>
<td>19133</td>
<td>&nbsp;</td>
<tr>
<td>RNase A</td>
<td>&nbsp;</td>
<td>Fisher</td>
<td>BP2539-100</td>
<td>10 &mu;g/ml</td>
</tr>
<tr>
<td>Safe Imager&trade; Blue light transilluminator</td>
<td>&nbsp;</td>
<td>Invitrogen</td>
<td>S37102</td>
<td>&nbsp;</td>
<tr>
<td>Sodium Dodecyl Sulfate (SDS)</td>
<td>&nbsp;</td>
<td>Sigma</td>
<td>L4509</td>
<td>20% SDS</td>
</tr>
<tr>
<td>Sterivex filters</td>
<td>&nbsp;</td>
<td>Fisher</td>
<td>SVG010RS</td>
<td>&nbsp;</td>
<tr>
<td>Sucrose</td>
<td>&nbsp;</td>
<td>Sigma</td>
<td>S0389</td>
<td>&nbsp;</td>
<tr>
<td>Table top centrifuge</td>
<td>&nbsp;</td>
<td>Eppendorf</td>
<td>5415D</td>
<td>&nbsp;</td>
<tr>
<td>TE buffer, pH 8.0</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Trizma&reg; base</td>
<td>&nbsp;</td>
<td>Sigma</td>
<td>T1503</td>
<td>&nbsp;</td>
<tr>
<td>Ultracentrifuge rotor, TLA 100</td>
<td>&nbsp;</td>
<td>Beckman Coulter</td>
<td>343847</td>
<td>&nbsp;</td>
<tr>
<td>Ultracentrifuge tube (7X20mm, PC)</td>
<td>&nbsp;</td>
<td>Beckman</td>
<td>343775</td>
<td>&nbsp;</td>
<tr>
<td>Ultracentrifuge tube rack</td>
<td>&nbsp;</td>
<td>Beckman</td>
<td>348302</td>
<td>&nbsp;</td>
<tr>
<td>Ultracentrifuge, Optima&reg; Max</td>
<td>&nbsp;</td>
<td>Beckman Coulter</td>
<td>&nbsp;</td>
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dna extraction from 0.22 &mu;m sterivex filters and cesium chloride density gradient centrifugation

This method is used to extract high molecular weight genomic DNA from planktonic biomass concentrated on 0.22 &mu;M Sterivex filters that have been treated with storage/lysis buffer and archived at -80&deg;C, and to purify this DNA using a cesium chloride density gradient.  The protocol begins with two one-hour incubation steps to liberate DNA from cells and remove RNA.  Next, a series of Phenol:Chloroform and Chloroform extractions are performed followed by centrifugation to remove proteins and cell membrane components, collection of the aqueous DNA extract, and several buffer exchange steps to wash and concentrate the extract.  Part Five describes the optional purification via cesium chloride density gradient.  It is recommended to work with less than 15 samples at one time to avoid confusion and cut down protocol time. The total time required for this protocol depends on the number of samples to be extracted. For 10-15 samples and assuming the proper centrifugation equipment is available, this entire protocol should take 3 days. Make sure you have the hybridization ovens set to temperature at the outset of the process.

Watch this Scientific Journal Video about DNA Extraction from 0.22 Î¼M Sterivex Filters and Cesium Chloride Density Gradient Centrifugation at JoVE.com

DNA Extraction from 0.22 &mu;M Sterivex Filters and Cesium Chloride Density Gradient Centrifugation

We describe a method for extraction of high molecular weight genomic DNA from planktonic biomass concentrated on 0.22 &mu;m Sterivex filters, followed by cesium chloride density gradient centrifugation for purification.

This method is used to extract high molecular weight genomic DNA from planktonic biomass concentrated on 0.22 &mu;M Sterivex filters that have been ...

dna-extraction-from-022-m-sterivex-filters-cesium-chloride-density

Research

JoVE Journal

Biology

Extraction of High Molecular Weight Genomic DNA from Soils and Sediments

The soil microbiome is a vast and relatively unexplored reservoir of genomic diversity and metabolic innovation that is intimately associated with nutrient and energy flow within terrestrial ecosystems. Cultivation-independent environmental genomic, also known as metagenomic, approaches promise unprecedented access to this genetic information with respect to pathway reconstruction and functional screening for high value therapeutic and biomass conversion processes. However, the soil microbiome still remains a challenge largely due to the difficulty in obtaining high molecular weight DNA of sufficient quality for large insert library production. Here we introduce a protocol for extracting high molecular weight, microbial community genomic DNA from soils and sediments. The quality of isolated genomic DNA is ideal for constructing large insert environmental genomic libraries for downstream sequencing and screening applications. 
The procedure starts with cell lysis. Cell walls and membranes of microbes are lysed by both mechanical (grinding) and chemical forces (&beta;-mercaptoethanol). Genomic DNA is then isolated using extraction buffer, chloroform-isoamyl alcohol and isopropyl alcohol. The buffers employed for the lysis and extraction steps include guanidine isothiocyanate and hexadecyltrimethylammonium bromide (CTAB) to preserve the integrity of the high molecular weight genomic DNA. Depending on your downstream application, the isolated genomic DNA can be further purified using cesium chloride (CsCl) gradient ultracentrifugation, which reduces impurities including humic acids. The first procedure, extraction, takes approximately 8 hours, excluding DNA quantification step. The CsCl gradient ultracentrifugation, is a two days process. During the entire procedure, genomic DNA should be treated gently to prevent shearing, avoid severe vortexing, and repetitive harsh pipetting.

A methodology to isolate high molecular weight and high quality genomic DNA from soil microbial community is described.

The soil microbiome is a vast and relatively unexplored reservoir of genomic diversity and metabolic innovation that is intimately associated with ...

DNA Extraction from Paraffin Embedded Material for Genetic and Epigenetic Analyses

Disease development and progression are characterized by frequent genetic and epigenetic aberrations including chromosomal rearrangements, copy number gains and losses and DNA methylation. Advances in high-throughput, genome-wide profiling technologies, such as microarrays, have significantly improved our ability to identify and detect these specific alterations. However as technology continues to improve, a limiting factor remains sample quality and availability. Furthermore, follow-up clinical information and disease outcome are often collected years after the initial specimen collection. Specimens, typically formalin-fixed and paraffin embedded (FFPE), are stored in hospital archives for years to decades. DNA can be efficiently and effectively recovered from paraffin-embedded specimens if the appropriate method of extraction is applied. High quality DNA extracted from properly preserved and stored specimens can support quantitative assays for comparisons of normal and diseased tissues and generation of genetic and epigenetic signatures 1. To extract DNA from paraffin-embedded samples, tissue cores or microdissected tissue are subjected to xylene treatment, which dissolves the paraffin from the tissue, and then rehydrated using a series of ethanol washes. Proteins and harmful enzymes such as nucleases are subsequently digested by proteinase K. The addition of lysis buffer, which contains denaturing agents such as sodium dodecyl sulfate (SDS), facilitates digestion 2. Nucleic acids are purified from the tissue lysate using buffer-saturated phenol and high speed centrifugation which generates a biphasic solution. DNA and RNA remain in the upper aqueous phase, while proteins, lipids and polysaccharides are sequestered in the inter- and organic-phases respectively. Retention of the aqueous phase and repeated phenol extractions generates a clean sample. Following phenol extractions, RNase A is added to eliminate contaminating RNA. Additional phenol extractions following incubation with RNase A are used to remove any remaining enzyme. The addition of sodium acetate and isopropanol precipitates DNA, and high speed centrifugation is used to pellet the DNA and facilitate isopropanol removal. Excess salts carried over from precipitation can interfere with subsequent enzymatic assays, but can be removed from the DNA by washing with 70% ethanol, followed by centrifugation to re-pellet the DNA 3. DNA is re-suspended in distilled water or the buffer of choice, quantified and stored at -20&deg;C. Purified DNA can subsequently be used in downstream applications which include, but are not limited to, PCR, array comparative genomic hybridization 4 (array CGH), methylated DNA Immunoprecipitation (MeDIP) and sequencing, allowing for an integrative analysis of tissue/tumor samples.

This video demonstrates the protocol for DNA extraction from formalin-fixed paraffin-embedded material. This is a multi-day procedure in which tissue sections are deparaffinized with xylene, rehydrated with ethanol and treated with proteinase K to purify and isolate DNA for subsequent gene-specific or genome-wide analysis.

Disease development and progression are characterized by frequent genetic and epigenetic aberrations including chromosomal rearrangements, copy number ...

Extraction of High Molecular Weight DNA from Microbial Mats

Successful and accurate analysis and interpretation of metagenomic data is dependent upon the efficient extraction of high-quality, high molecular weight (HMW) community DNA. However, environmental mat samples often pose difficulties to obtaining large concentrations of high-quality, HMW DNA. Hypersaline microbial mats contain high amounts of extracellular polymeric substances (EPS)1 and salts that may inhibit downstream applications of extracted DNA. Direct and harsh methods are often used in DNA extraction from refractory samples. These methods are typically used because the EPS in mats, an adhesive matrix, binds DNA2,3 during direct lysis. As a result of harsher extraction methods, DNA becomes fragmented into small sizes4,5,6.
The DNA thus becomes inappropriate for large-insert vector cloning. In order to circumvent these limitations, we report an improved methodology to extract HMW DNA of good quality and quantity from hypersaline microbial mats. We employed an indirect method involving the separation of microbial cells from the background mat matrix through blending and differential centrifugation. A combination of mechanical and chemical procedures was used to extract and purify DNA from the extracted microbial cells. Our protocol yields approximately 2 &mu;g of HMW DNA (35-50 kb) per gram of mat sample, with an A260/280 ratio of 1.6. Furthermore, amplification of 16S rRNA genes7 suggests that the protocol is able to minimize or eliminate any inhibitory effects of contaminants. Our results provide an appropriate methodology for the extraction of HMW DNA from microbial mats for functional metagenomic studies and may be applicable to other environmental samples from which DNA extraction is challenging.

We provide an improved protocol for extracting high molecular weight DNA from hypersaline microbial mats. Microbial cells are separated from the mat matrix prior to DNA extraction and purification. This enhances the concentrations, quality, and size of the DNA. The protocol may be used for other refractory samples.

Successful and accurate analysis and interpretation of metagenomic data is dependent upon the efficient extraction  of high-quality, high molecular weight ...

The Infiltration-centrifugation Technique for Extraction of Apoplastic Fluid from Plant Leaves Using Phaseolus vulgaris as an Example

The apoplast is a distinct extracellular compartment in plant tissues that lies outside the plasma membrane and includes the cell wall. The apoplastic compartment of plant leaves is the site of several important biological processes, including cell wall formation, cellular nutrient and water uptake and export, plant-endophyte interactions and defence responses to pathogens. The infiltration-centrifugation method is well established as a robust technique for the analysis of the soluble apoplast composition of various plant species. The fluid obtained by this method is commonly known as apoplast washing fluid (AWF). The following protocol describes an optimized vacuum infiltration and centrifugation method for AWF extraction from Phaseolus vulgaris (French bean) cv. Tendergreen leaves. The limitations of this method and the optimization of the protocol for other plant species are discussed. Recovered AWF can be used in a wide range of downstream experiments that seek to characterize the composition of the apoplast and how it varies in response to plant species and genotype, plant development and environmental conditions, or to determine how microorganisms grow in apoplast fluid and respond to changes in its composition.

The Infiltration-centrifugation Technique for Extraction of Apoplastic Fluid from Plant Leaves Using Phaseolus vulgaris as an Example

This protocol details the optimized extraction of apoplast washing fluid from plant leaves, using French bean plants (Phaseolus vulgaris) as a model example.

The apoplast is a distinct extracellular compartment in plant tissues that lies outside the plasma membrane and includes the cell wall. The apoplastic ...

A Hybrid DNA Extraction Method for the Qualitative and Quantitative Assessment of Bacterial Communities from Poultry Production Samples

The efficacy of DNA extraction protocols can be highly dependent upon both the type of sample being investigated and the types of downstream analyses performed. Considering that the use of new bacterial community analysis techniques (e.g., microbiomics, metagenomics) is becoming more prevalent in the agricultural and environmental sciences and many environmental samples within these disciplines can be physiochemically and microbiologically unique (e.g., fecal and litter/bedding samples from the poultry production spectrum), appropriate and effective DNA extraction methods need to be carefully chosen. Therefore, a novel semi-automated hybrid DNA extraction method was developed specifically for use with environmental poultry production samples. This method is a combination of the two major types of DNA extraction: mechanical and enzymatic. A two-step intense mechanical homogenization step (using bead-beating specifically formulated for environmental samples) was added to the beginning of the &#8220;gold standard&#8221; enzymatic DNA extraction method for fecal samples to enhance the removal of bacteria and DNA from the sample matrix and improve the recovery of Gram-positive bacterial community members. Once the enzymatic extraction portion of the hybrid method was initiated, the remaining purification process was automated using a robotic workstation to increase sample throughput and decrease sample processing error. In comparison to the strict mechanical and enzymatic DNA extraction methods, this novel hybrid method provided the best overall combined performance when considering quantitative (using 16S rRNA qPCR) and qualitative (using microbiomics) estimates of the total bacterial communities when processing poultry feces and litter samples.

A novel semi-automated hybrid DNA extraction method for use with environmental poultry production samples was developed and demonstrated improvements over a common mechanical and enzymatic extraction method in terms of the quantitative and qualitative estimates of the total bacterial communities.

The efficacy of DNA extraction protocols can be highly dependent upon both the type of sample being investigated and the types of downstream analyses ...

Filtration Isolation of Nucleic Acids:  A Simple and Rapid DNA Extraction Method

FINA, filtration isolation of nucleic acids, is a novel extraction method which utilizes vertical filtration via a separation membrane and absorbent pad to extract cellular DNA from whole blood in less than 2 min. The blood specimen is treated with detergent, mixed briefly and applied by pipet to the separation membrane. The lysate wicks into the blotting pad due to capillary action, capturing the genomic DNA on the surface of the separation membrane. The extracted DNA is retained on the membrane during a simple wash step wherein PCR inhibitors are wicked into the absorbent blotting pad. The membrane containing the entrapped DNA is then added to the PCR reaction without further purification. This simple method does not require laboratory equipment and can be easily implemented with inexpensive laboratory supplies. Here we describe a protocol for highly sensitive detection and quantitation of HIV-1 proviral DNA from 100 &#181;l whole blood as a model for early infant diagnosis of HIV that could readily be adapted to other genetic targets.

We describe here a simple and rapid paper-based DNA extraction method of HIV proviral DNA from whole blood detected by quantitative PCR. This protocol can be extended for use in detecting other genetic markers or using alternative amplification methods.

FINA, filtration isolation of nucleic acids, is a novel extraction method which utilizes vertical filtration via a separation membrane and absorbent pad ...

Sperm Collection of Differential Quality Using Density Gradient Centrifugation

In sexual reproduction, a male gamete or sperm cell fuses with a female gamete to bring about fertilization. However, a large number of sperm cells with fertilizing ability are required to interact with a female gamete to ensure fertilization. As such, the fertilizing ability of individual sperm cells is critical for successful reproduction. Density gradient centrifugation has been utilized for several decades as a reproducible, fast, efficient, effective and extremely adaptable method to collect only high-quality sperm to be used in assisted reproductive technology. The protocols we described herein focus on the utilization of the discontinuous Percoll density gradient centrifugation (PDGC) technique to isolate three distinct populations of rooster sperm by their quality. We were able to collect low-, medium- and high-quality sperm. We also describe reproducible protocols that entail determining fertility potential of sperm by assessing their viability, mobility and penetrability. Collection of sperm by their quality using PDGC technique would be useful to accurately and thoroughly characterize sperm with differential fertility potential.

In this paper, we aim to describe the performance of the density gradient centrifugation technique and its application in sperm physiology research.

In sexual reproduction, a male gamete or sperm cell fuses with a female gamete to bring about fertilization. However, a large number of sperm cells with ...

A Magnetic-Bead-Based Mosquito DNA Extraction Protocol for Next-Generation Sequencing

A recently published DNA extraction protocol using magnetic beads and an automated DNA extraction instrument suggested that it is possible to extract high quality and quantity DNA from a well-preserved individual mosquito sufficient for downstream whole genome sequencing. However, reliance on an expensive automated DNA extraction instrument can be prohibitive for many laboratories. Here, the study provides a budget-friendly magnetic-bead-based DNA extraction protocol, which is suitable for low to medium throughput. The protocol described here was successfully tested using individual Aedes aegypti mosquito samples. The reduced costs associated with high quality DNA extraction will increase the application of high throughput sequencing to resource limited labs and studies.

Described here is a DNA extraction protocol using magnetic beads to produce high quality DNA extractions from mosquitoes. These extractions are suitable for a downstream next-generation sequencing approach.

A recently published DNA extraction protocol using magnetic beads and an automated DNA extraction instrument suggested that it is possible to extract high ...

Small-Scale Extraction of Caenorhabditis elegans Genomic DNA

Genomic DNA extraction from single or a few Caenorhabditis elegans has many downstream applications, including PCR for genotyping lines, cloning, and sequencing. The traditional proteinase K-based methods for genomic DNA extraction from C. elegans take several hours. Commercial extraction kits that effectively break open the C. elegans cuticle and extract genomic DNA are limited. An easy, faster (~15 min), and cost-efficient method of extracting C. elegans genomic DNA that works well for classroom and research applications is reported here. This DNA extraction method is optimized to use single or a few late-larval (L4) or adult nematodes as starting material for obtaining a reliable template to perform PCR. The results indicate that the DNA quality is suitable for amplifying gene targets of different sizes by PCR, permitting genotyping of single or a few animals even at dilutions to one-fiftieth of the genomic DNA from a single adult per reaction. The reported protocols can be reliably used to quickly produce DNA template from a single or a small sample of C. elegans for PCR-based applications.

Small-Scale Extraction of Caenorhabditis elegans Genomic DNA

Presented here is a description of the straightforward and relatively rapid isolation of Caenorhabditis elegans genomic DNA from one or a few animals using a commercially available tissue kit. The resulting gDNA preparation is a suitable template for PCR.

Genomic DNA extraction from single or a few Caenorhabditis elegans has many downstream applications, including PCR for genotyping lines, cloning, and ...

Enhanced Bacterial Extracellular Vesicles Isolation for Microbiota Multi-Omics

Isolation and Purification of Bacterial Extracellular Vesicles from Human Feces Using Density Gradient Centrifugation

Bacterial extracellular vesicles (BEVs) are nanovesicles derived from bacteria that play an active role in bacteria-bacteria and bacteria-host communication, transferring bioactive molecules such as proteins, lipids, and nucleic acids inherited from the parent bacteria. BEVs derived from the gut microbiota have effects within the gastrointestinal tract and can reach distant organs, resulting in significant implications for physiology and pathology. Theoretical investigations that explore the types, quantities, and roles of BEVs derived from human feces are crucial for understanding the secretion and function of BEVs from the gut microbiota. These investigations also necessitate an improvement in the current strategy for isolating and purifying BEVs.
This study optimized the isolation and purification process of BEVs by establishing two density gradient centrifugation (DGC) modes: Top-down and Bottom-up. The enriched distribution of BEVs was determined in fractions 6 to 8 (F6-F8). The effectiveness of the approach was evaluated based on particle morphology, size, concentration, and protein content. The particle and protein recovery rates were calculated, and the presence of specific markers was analyzed to compare the recovery and purity of the two DGC modes. The results indicated that the Top-down centrifugation mode had lower contamination levels and achieved a recovery rate and purity similar to that of the Bottom-up mode. A centrifugation time of 7 h was sufficient to achieve a fecal BEV concentration of 108/mg.
Apart from feces, this method could be applied to other body fluid types with proper modification according to the differences in components and viscosity. In conclusion, this detailed and reliable protocol would facilitate the standardized isolation and purification of BEVs and thus, lay a foundation for subsequent multi-omics analysis and functional experiments.

Author Spotlight: Accelerating Research on Bacterial Extracellular Vesicles Separation and Heterogeneity 

This study describes a method to isolate and purify bacterial extracellular vesicles (BEVs) enriched from human feces via density gradient centrifugation (DGC), identifies the physical characteristics of BEVs from morphology, particle size, and concentration, and discusses the potential applications of the DGC approach in clinical and scientific research.