We acknowledge funding support from the Pacific Southwest Regional Center of Excellence for Vector-Borne Diseases funded by the U.S. Centers for Disease Control and Prevention (Cooperative Agreement 1U01CK000516), CDC grant NU50CK000420-04-04, the USDA National Institute of Food and Agriculture (Hatch project 1025565), UF/IFAS Florida Medical Entomology Laboratory fellowship to Tse-Yu Chen, NSF CAMTech IUCRC Phase II grant (AWD05009_MOD0030), and Florida Department of Health (Contract CODQJ). The findings and conclusions in this article are those of the author(s) and do not necessarily represent the views of the U.S. Fish and Wildlife Service.

1. General sample storage and preparations prior to DNA extraction
<ol>
	<li>Hydrate the sample in 100 &#181;L PCR-grade water for 1 h (or overnight) at 4 &#176;C if the sample has been stored in &#62;70% alcohol to soften the tissue.</li>
</ol>
2. Sample disruption
<ol>
	<li>Set an incubator or shaking heat block at 56 &#176;C.</li>
	<li>Make proteinase K (PK) buffer/enzyme mix. 2 &#181;L of Proteinase K (100 mg/mL) and 98 &#181;L of Proteinase K Buffer (total 100 &#181;L) is required for each individual mosquito extraction. To prepare a master mix for multiple specimens, increase the total amount (combined for all individual specimens) by ~15% to ensure the availability of adequate volume.</li>
	<li>If samples were hydrated prior to extraction, discard water from each sample tube.</li>
	<li>In a 1.5 mL microcentrifuge tube containing mosquito tissue, add 100 &#181;L of PK buffer/enzyme mix.</li>
	<li>Homogenize the tissue using microcentrifuge tube pestle.</li>
	<li>Centrifuge the samples for 1 min at 9,600 x g at room temperature.</li>
	<li>Incubate the sample for 2-3 h at 56 &#176;C.</li>
	<li>During incubation, prepare the other reagents using the DNA extraction step (step 3).</li>
</ol>
3. DNA extraction
<ol>
	<li>Make a magnetic bead master mix. For each sample, mix 100 &#181;L of lysis buffer, 100 &#181;L of Isopropanol, and 15 &#181;L of magnetic beads (total 215 &#181;L). To prepare a master mix for multiple reactions, increase the total amount (combined for all individual specimens) by ~20% to ensure the availability of adequate volume.</li>
	<li>After the incubation time (step 2.7), transfer each lysate to a clean microcentrifuge tube or a microplate well using pipette.</li>
	<li>Add 100 &#181;L lysate and 215 &#181;L of the magnetic bead master mix to each sample.</li>
	<li>Use a pipette to mix it well for 10-20 s and then let it stand for 10 min at room temperature. Gently shake the tube occasionally to maximize the binding of magnetic beads and DNA.</li>
	<li>Place the tube/plate on the magnetic bead separator and wait until the solution is clear.</li>
	<li>Discard the liquid from the tube/plate using pipette. When removing the supernatant, try not to touch or disturb the magnetic beads holding the DNA.</li>
	<li>Move the tube/plate away from magnetic bead separator and add 325 &#181;L of washing buffer 1 to each well.</li>
	<li>Mix thoroughly by pipetting and incubate for 1 min at room temperature.</li>
	<li>Repeat steps 3.5-3.6.</li>
	<li>Move the tube/plate away from magnetic bead separator and add 250 &#181;L of washing buffer 1 to each well.</li>
	<li>Mix thoroughly by pipetting and incubate for 1 min at room temperature.</li>
	<li>Repeat steps 3.5-3.6.</li>
	<li>Move the tube/plate away from magnetic bead separator and add 250 &#181;L of washing buffer 2 to each sample.</li>
	<li>Mix thoroughly and incubate for 1 min at room temperature.</li>
	<li>Repeat steps 3.5-3.6.</li>
	<li>Move the tube/plate away from magnetic bead separator and add 250 &#181;L of washing buffer 2 to each well.</li>
	<li>Mix thoroughly and incubate for 1 min at room temperature.</li>
	<li>Repeat steps 3.5-3.6.</li>
	<li>Move the tube/plate away from the magnetic bead separator and add 100 &#181;L of elution buffer to each well.</li>
	<li>Mix thoroughly and incubate for 2 min at room temperature.</li>
	<li>Move the tube/plate over on the magnetic bead separator and wait until the solution is clear.</li>
	<li>Pipette the supernatant into a new clean 0.5 microcentrifuge tube or microplate well.</li>
	<li>Store DNA samples at 4 &#176;C (up to 1 week) or -80 &#176;C.&#160;If a microplate is being used, cover it with parafilm.</li>
	<li>Determine the DNA yields using any appropriate method. 
	NOTE: In this study, DNA fluorometer reading and absorbance at 260/280 nm were utilized.</li>
</ol>

<ol>
	<li>Nieman, C. C., Yamasaki, Y., Collier, T. C., Lee, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+DNA+extraction+protocol+for+improved+DNA+yield+from+individual+mosquitoes.">A DNA extraction protocol for improved DNA yield from individual mosquitoes.</a> F1000Research. 4, 1314 (2015).</li><li>Lee, 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=Genome-wide+divergence+among+invasive+populations+of+Aedes+aegypti+in+California.">Genome-wide divergence among invasive populations of Aedes aegypti in California.</a> BMC Genomics. 20 (1), 204 (2019).</li><li>Schmidt, H., 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=Abundance+of+conserved+CRISPR-Cas9+target+sites+within+the+highly+polymorphic+genomes+of+Anopheles+and+Aedes+mosquitoes.">Abundance of conserved CRISPR-Cas9 target sites within the highly polymorphic genomes of Anopheles and Aedes mosquitoes.</a> Nature Communications. 11 (1), 1425 (2020).</li><li>Schmidt, H., 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=Transcontinental+dispersal+of+Anopheles+gambiae+occurred+from+West+African+origin+via+serial+founder+events.">Transcontinental dispersal of Anopheles gambiae occurred from West African origin via serial founder events.</a> Communications Biology. 2, 473 (2019).</li><li>Norris, L. 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=Adaptive+introgression+in+an+African+malaria+mosquito+coincident+with+the+increased+usage+of+insecticide-treated+bed+nets.">Adaptive introgression in an African malaria mosquito coincident with the increased usage of insecticide-treated bed nets.</a> Proceedings of the National Academy of Sciences of the United States of America. 112 (3), 815-820 (2015).</li><li>Main, B. 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=The+genetic+basis+of+host+preference+and+resting+behavior+in+the+major+african+malaria+vector,+Anopheles+arabiensis.">The genetic basis of host preference and resting behavior in the major african malaria vector, Anopheles arabiensis.</a> Plos Genetics. 12 (9), 1006303 (2016).</li><li>Yamasaki, Y. K., 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=Improved+tools+for+genomic+DNA+library+construction+of+small+insects.">Improved tools for genomic DNA library construction of small insects.</a> F1000Research. 5, 211 (2016).</li><li>Tabuloc, C. 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+of+Tuta+absoluta+genome+to+develop+SNP+genotyping+assays+for+species+identification.">Sequencing of Tuta absoluta genome to develop SNP genotyping assays for species identification.</a> Journal of Pest Science. 92, 1397-1407 (2019).</li><li>Campos, M., 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=Complete+mitogenome+sequence+of+Anopheles+coustani+from+S&#227;o+Tom&#233;+island.">Complete mitogenome sequence of Anopheles coustani from S&#227;o Tom&#233; island.</a> Mitochondrial DNA. Part B, Resources. 5 (3), 3376-3378 (2020).</li><li>Cornel, A. 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=Complete+mitogenome+sequences+of+Aedes+(Howardina)+busckii+and+Aedes+(Ochlerotatus)+taeniorhynchus+from+the+Caribbean+Island+of+Saba.">Complete mitogenome sequences of Aedes (Howardina) busckii and Aedes (Ochlerotatus) taeniorhynchus from the Caribbean Island of Saba.</a> Mitochondrial DNA. Part B, Resources. 5 (2), 1163-1164 (2020).</li><li>Lucena-Aguilar, G., 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=DNA+source+selection+for+downstream+applications+based+on+dna+quality+indicators+analysis.">DNA source selection for downstream applications based on dna quality indicators analysis.</a> Biopreservation and Biobanking. 14 (4), 264-270 (2016).</li></ol>

The authors have nothing to disclose.

The protocol described here can be adapted for other insect species. The original version of the protocol introduced in Nieman et al.1 has been tested on multiple species, including Aedes aegypti, Ae. busckii, Ae. taeniorhynchus, Anopheles arabiensis, An. coluzzii, An. coustani, An. darlingi, An. funestus, An. gambiae, An. quadriannulatus, An. rufipes, Culex pipiens, Cx. quinquefasciatus, Cx. theileri, Drosophila suzukii, Chrysomela aeneicollis Tuta absoluta, and Keiferia lycopersicella2,8,9,10. It is expected that this protocol will work for these as well as other arthropods.
Ideally, samples should be stored in 70%-80% ethanol at 4 &#176;C prior to DNA extraction. Typically, 80% ethanol is used for storing mosquito samples in Africa. High temperature conditions could accelerate evaporation of ethanol and make ethanol content lower than what is intended (70%). Samples stored in 100% ethanol, denatured alcohol, 75%-90% isopropanol or rubbing alcohol have also resulted in successful whole genome sequencing using&#160;the Nieman et al.1 protocol, and it is expected that this protocol would perform equally well. The DNA extraction protocol described here has also been tried on samples stored dry in silica and frozen at -20 &#176;C. However, there was a higher (15%-30%) chance of failure when stored for &#62;6-12 months, suggesting that these were less than ideal storage conditions.
As DNA extraction without physical sample disruption has a higher chance of failure (33%)1, this protocol incorporates a manual physical disruption technique (step 2.5). Sample disruption can also be achieved using steel beads on a tissue lysis instrument1.
The reagents and consumable cost for DNA extraction using this protocol is comparable with other extraction methods available (Table 1). However, the protocol described here does not require an automated DNA extraction instrument. Due to manual labor involved in processing DNA extraction, one person can typically process 12-16 samples and finish with DNA quantification in a day. This is significantly less than what automated DNA extraction setup can process per day. Thus, when choosing a protocol, the sample processing capacity should be taken into account. However, the lower cost threshold this protocol offers should enable many resource limited labs and studies to leverage in high-throughput sequencing technology.
In both the Nieman et al.1 and this protocol, elution buffer can be replaced with the typical TE buffer, 10 mM Tris-Cl, or water depending on the downstream analysis. An elution buffer containing some EDTA may impact enzyme efficiency. Typical enzymatic shearing-based gDNA library preparation protocols include conditioning solutions or enhancers added to compensate for enzyme inhibition by EDTA. It should also be considered that EDTA may change the absorbance at 230 nm wavelength11. For example, higher concentrations of EDTA would create a higher absorbance value between 220-240 nm wavelength than that shown in Figure 1 (data not shown).
This protocol can be easily adapted to laboratories with minimal molecular biology tools. The protocol described here attempts to reduce the cost thresholds associated with genome extraction and thereby increase the application of high throughput sequencing to resource limited labs and studies.

Recent development of an improved DNA extraction protocol1 has allowed many high-impact downstream studies involving whole genome sequencing2,3,4,5,6. This magnetic bead-based DNA extraction protocol provides reliable DNA yield from individual mosquito samples, which in turn reduces the cost and time associated with acquiring a sufficient number of samples from field collections.
Recent advances in population and landscape genomics are directly correlated with decreasing costs of whole genome sequencing. Though the previous DNA extraction protocol1 increases efficiencies associated with high throughput sequencing, smaller labs/studies without the funds may opt out of using these new powerful landscape and population genomics tools due to costs of implementing the protocol (e.g., costs of specialized instruments).
Here, a modified DNA extraction protocol is presented that uses a similar magnetic bead extraction step as Neiman et al.1 to obtain high purity DNA but does not rely on high-cost instruments for tissue lysis and DNA extraction. This protocol is suitable for experiments requiring &#62;10 ng of high-quality DNA.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>AE Buffer</td>
			<td>Qiagen</td>
			<td>19077</td>
			<td>Elution buffer</td>
		</tr>
		<tr>
			<td>AL Buffer</td>
			<td>Qiagen</td>
			<td>19075</td>
			<td>Lysis buffer</td>
		</tr>
		<tr>
			<td>AW1 Buffer</td>
			<td>Qiagen</td>
			<td>19081</td>
			<td>Washing buffer 1</td>
		</tr>
		<tr>
			<td>AW2 Buffer</td>
			<td>Qiagen</td>
			<td>19072</td>
			<td>Washing buffer 2</td>
		</tr>
		<tr>
			<td>MagAttract Suspension G</td>
			<td>Qiagen</td>
			<td>1026901</td>
			<td>magnetic bead</td>
		</tr>
		<tr>
			<td>Magnetic bead separator</td>
			<td>Epigentek</td>
			<td>Q10002-1</td>
			<td></td>
		</tr>
		<tr>
			<td>Nanodrop</td>
			<td>ThermoFisher</td>
			<td>ND-2000</td>
			<td>microvolume spectrophotometer</td>
		</tr>
		<tr>
			<td>PK Buffer</td>
			<td>ThermoFisher</td>
			<td>4489111</td>
			<td>Proteinase K buffer</td>
		</tr>
		<tr>
			<td>Proteinase K</td>
			<td>ThermoFisher</td>
			<td>A25561</td>
			<td></td>
		</tr>
		<tr>
			<td>Qubit</td>
			<td>Invitrogen</td>
			<td>Q33238</td>
			<td>fluorometer</td>
		</tr>
	</tbody>
</table>

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.

The average DNA yield per individual mosquito head/thorax tissue was 4.121 ng/&#181;L (N = 92, standard deviation 3.513) measured using a fluorometer when eluted using 100 &#181;L of elution buffer. This is sufficient for the 10-30 ng genomic DNA input requirements necessary for whole genome library construction1,7. The quantity of DNA can vary between 0.3-29.7 ng/&#181;L depending on the mosquito body size and preservation conditions. Some of the high variability is due to the characteristic of magnetic beads used in the study. Different brands of magnetic beads may produce more consistent concentrations, as indicated in the previous report1. It should also be noted that different mosquito species differ in size and that the DNA yield is dependent on those individual and species size ranges. If the DNA concentration is below the typical ranges, one may adjust the incubation period in the proteinase K reaction (step 2.7), but this extension should be no longer than 16 h. Moreover, switching the proteinase K and/or lysis buffer brands can have significant impact on DNA yield1.
The typical microvolume fluorometer reading of the final DNA in elution buffer with 0.5 mM EDTA is shown in Figure 1. The average absorbance ratio for 260/280 nm was 2.3 (standard deviation = 0.071). The data was consistent from the samples used in the previous studies for whole genome sequencing3,4.
Typical reagent and consumable cost for extraction is around $9.50/sample. These cost estimates include reagents listed in the Table of Materials, and other consumables such as pipette tips, tubes, and gloves needed for extraction. The reagent and consumable cost are equivalent to any typical magnetic-bead-based extraction method (Table 1). The cost may vary somewhat depending on bulk purchase discounts available for any given product. The major cost benefit of this protocol comes from not requiring the automated DNA extraction instrument.
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/62354/62354fig01.jpg" /> 
Figure 1: Fluorometer output. Typical DNA fluorometer output of mosquito DNA eluted in elution buffer with 0.5 mM EDTA. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/62354/62354fig01large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
Table 1: Cost analysis for different extraction methods. The table lists the costs and the number of samples processed in one working day for different extraction methods. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/62354/Table 1-62354_R1.docx" target="_blank">Please click here to download this Table.</a>

Watch this Scientific Journal Video about A Magnetic-Bead-Based Mosquito DNA Extraction Protocol for Next-Generation Sequencing at JoVE.com

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

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 ...

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6.2K Views.  University of Florida. 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.

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

Protocol for Mosquito Rearing (A. gambiae)

This protocol describes mosquito rearing in the insectary. The insectary rooms are maintained at 28&deg;C and ~80% humidity, with a 12 hr. day/night cycle. For this procedure, you'll need mosquito cages, 10% sterile sucrose solution, paper towels, beaker, whatman filter paper, glass feeders, human blood and serum, water bath, parafilm, distilled water, clean plastic trays, mosquito food (described below), mosquito net to cover the trays, vacuum, and a collection chamber to collect adults.

Protocol for Mosquito Rearing A. gambiae

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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 ...

Fluorescence-microscopy Screening and Next-generation Sequencing: Useful Tools for the Identification of Genes Involved in Organelle Integrity

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A fundamental quest in cell biology is to define the mechanisms that underlie the identity of the organelles that make eukaryotic cells. Here we propose a method to identify the genes responsible for the morphological and functional integrity of plant organelles using fluorescence microscopy and next-generation sequencing tools.

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Next-generation Sequencing of 16S Ribosomal RNA Gene Amplicons

One of the major questions in microbial ecology is &#8220;who is there?&#8221; This question can be answered using various tools, but one of the long-lasting gold standards is to sequence 16S ribosomal RNA (rRNA) gene amplicons generated by domain-level PCR reactions amplifying from genomic DNA. Traditionally, this was performed by cloning and Sanger (capillary electrophoresis) sequencing of PCR amplicons. The advent of next-generation sequencing has tremendously simplified and increased the sequencing depth for 16S rRNA gene sequencing. The introduction of benchtop sequencers now allows small labs to perform their 16S rRNA sequencing in-house in a matter of days. Here, an approach for 16S rRNA gene amplicon sequencing using a benchtop next-generation sequencer is detailed. The environmental DNA is first amplified by PCR using primers that contain sequencing adapters and barcodes. They are then coupled to spherical particles via emulsion PCR. The particles are loaded on a disposable chip and the chip is inserted in the sequencing machine after which the sequencing is performed. The sequences are retrieved in fastq format, filtered and the barcodes are used to establish the sample membership of the reads. The filtered and binned reads are then further analyzed using publically available tools. An example analysis where the reads were classified with a taxonomy-finding algorithm within the software package Mothur is given. The method outlined here is simple, inexpensive and straightforward and should help smaller labs to take advantage from the ongoing genomic revolution.

Characterizing microbial community has been a longstanding goal in environmental microbiology. Next-generation sequencing methods now allow for the characterization of microbial communities at an unprecedented depth with minimal cost and labor. We detail here our approach to sequence bacterial 16S ribosomal RNA genes using a benchtop sequencer.

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Physiological Recordings and RNA Sequencing of the Gustatory Appendages of the Yellow-fever Mosquito Aedes aegypti

Electrophysiological recording of action potentials from sensory neurons of mosquitoes provides investigators a glimpse into the chemical perception of these disease vectors. We have recently identified a bitter sensing neuron in the labellum of female Aedes aegypti that responds to DEET and other repellents, as well as bitter quinine, through direct electrophysiological investigation. These gustatory receptor neuron responses prompted our sequencing of total mRNA from both male and female labella and tarsi samples to elucidate the putative chemoreception genes expressed in these contact chemoreception tissues. Samples of tarsi were divided into pro-, meso- and metathoracic subtypes for both sexes. We then validated our dataset by conducting qRT-PCR on the same tissue samples and used statistical methods to compare results between the two methods. Studies addressing molecular function may now target specific genes to determine those involved in repellent perception by mosquitoes. These receptor pathways may be used to screen novel repellents towards disruption of host-seeking behavior to curb the spread of harmful viruses.

Physiological Recordings and RNA Sequencing of the Gustatory Appendages of the Yellow-fever Mosquito Aedes aegypti

Using two methods to estimate gene expression in the major gustatory appendages of Aedes aegypti, we have identified the set of genes putatively underlying the neuronal responses to bitter and repulsive compounds, as determined by electrophysiological examination.

Electrophysiological recording of action potentials from sensory neurons of mosquitoes provides investigators a glimpse into the chemical perception of ...

Targeted DNA Methylation Analysis by Next-generation Sequencing

The role of epigenetic processes in the control of gene expression has been known for a number of years. DNA methylation at cytosine residues is of particular interest for epigenetic studies as it has been demonstrated to be both a long lasting and a dynamic regulator of gene expression. Efforts to examine epigenetic changes in health and disease have been hindered by the lack of high-throughput, quantitatively accurate methods. With the advent and popularization of next-generation sequencing (NGS) technologies, these tools are now being applied to epigenomics in addition to existing genomic and transcriptomic methodologies. For epigenetic investigations of cytosine methylation where regions of interest, such as specific gene promoters or CpG islands, have been identified and there is a need to examine significant numbers of samples with high quantitative accuracy, we have developed a method called Bisulfite Amplicon Sequencing (BSAS). This method combines bisulfite conversion with targeted amplification of regions of interest, transposome-mediated library construction and benchtop NGS. BSAS offers a rapid and efficient method for analysis of up to 10 kb of targeted regions in up to 96 samples at a time that can be performed by most research groups with basic molecular biology skills. The results provide absolute quantitation of cytosine methylation with base specificity. BSAS can be applied to any genomic region from any DNA source. This method is useful for hypothesis testing studies of target regions of interest as well as confirmation of regions identified in genome-wide methylation analyses such as whole genome bisulfite sequencing, reduced representation bisulfite sequencing, and methylated DNA immunoprecipitation sequencing.

Bisulfite amplicon sequencing (BSAS) is a method for quantifying cytosine methylation in targeted genomic regions of interest. This method uses bisulfite conversion paired with PCR amplification of target regions prior to next-generation sequencing to produce absolute quantitation of DNA methylation at a base-specific level.

The role of epigenetic processes in the control of gene expression has been known for a number of years. DNA methylation at cytosine residues is of ...

Amplification, Next-generation Sequencing, and Genomic DNA Mapping of Retroviral Integration Sites

Retroviruses exhibit signature integration preferences on both the local and global scales. Here, we present a detailed protocol for (1) generation of diverse libraries of retroviral integration sites using ligation-mediated PCR (LM-PCR) amplification and next-generation sequencing (NGS), (2) mapping the genomic location of each virus-host junction using BEDTools, and (3) analyzing the data for statistical relevance. Genomic DNA extracted from infected cells is fragmented by digestion with restriction enzymes or by sonication. After suitable DNA end-repair, double-stranded linkers are ligated onto the DNA ends, and semi-nested PCR is conducted using primers complementary to both the long terminal repeat (LTR) end of the virus and the ligated linker DNA. The PCR primers carry sequences required for DNA clustering during NGS, negating the requirement for separate adapter ligation. Quality control (QC) is conducted to assess DNA fragment size distribution and adapter DNA incorporation prior to NGS. Sequence output files are filtered for LTR-containing reads, and the sequences defining the LTR and the linker are cropped away. Trimmed host cell sequences are mapped to a reference genome using BLAT and are filtered for minimally 97% identity to a unique point in the reference genome. Unique integration sites are scrutinized for adjacent nucleotide (nt) sequence and distribution relative to various genomic features. Using this protocol, integration site libraries of high complexity can be constructed from genomic DNA in three days. The entire protocol that encompasses exogenous viral infection of susceptible tissue culture cells to integration site analysis can therefore be conducted in approximately one to two weeks. Recent applications of this technology pertain to longitudinal analysis of integration sites from HIV-infected patients.

We describe a protocol for amplifying retroviral integration sites from the genomic DNA of infected cells, sequencing the amplified virus-host junctions, and then mapping these sequences to a reference genome. We also describe techniques to quantify the distribution of integration sites relative to various genomic annotations using BEDTools.

Retroviruses exhibit signature integration preferences on both the local and global scales. Here, we present a detailed protocol for (1) generation of ...

Efficient Nucleic Acid Extraction and 16S rRNA Gene Sequencing for Bacterial Community Characterization

There is a growing appreciation for the role of microbial communities as critical modulators of human health and disease. High throughput sequencing technologies have allowed for the rapid and efficient characterization of bacterial communities using 16S rRNA gene sequencing from a variety of sources. Although readily available tools for 16S rRNA sequence analysis have standardized computational workflows, sample processing for DNA extraction remains a continued source of variability across studies. Here we describe an efficient, robust, and cost effective method for extracting nucleic acid from swabs. We also delineate downstream methods for 16S rRNA gene sequencing, including generation of sequencing libraries, data quality control, and sequence analysis. The workflow can accommodate multiple samples types, including stool and swabs collected from a variety of anatomical locations and host species. Additionally, recovered DNA and RNA can be separated and used for other applications, including whole genome sequencing or RNA-seq. The method described allows for a common processing approach for multiple sample types and accommodates downstream analysis of genomic, metagenomic and transcriptional information.

We describe an efficient, robust, and cost effective method for extracting nucleic acid from swabs for characterization of bacterial communities using 16S rRNA gene amplicon sequencing. The method allows for a common processing approach for multiple sample types and accommodates a number of downstream analytic processes.

There is a growing appreciation for the role of microbial communities as critical modulators of human health and disease. High throughput sequencing ...

A Protocol for Functional Assessment of Whole-Protein Saturation Mutagenesis Libraries Utilizing High-Throughput Sequencing

Site-directed mutagenesis has long been used as a method to interrogate protein structure, function and evolution. Recent advances in massively-parallel sequencing technology have opened up the possibility of assessing the functional or fitness effects of large numbers of mutations simultaneously. Here, we present a protocol for experimentally determining the effects of all possible single amino acid mutations in a protein of interest utilizing high-throughput sequencing technology, using the 263 amino acid antibiotic resistance enzyme TEM-1 &#946;-lactamase as an example. In this approach, a whole-protein saturation mutagenesis library is constructed by site-directed mutagenic PCR, randomizing each position individually to all possible amino acids. The library is then transformed into bacteria, and selected for the ability to confer resistance to &#946;-lactam antibiotics. The fitness effect of each mutation is then determined by deep sequencing of the library before and after selection. Importantly, this protocol introduces methods which maximize sequencing read depth and permit the simultaneous selection of the entire mutation library, by mixing adjacent positions into groups of length accommodated by high-throughput sequencing read length and utilizing orthogonal primers to barcode each group. Representative results using this protocol are provided by assessing the fitness effects of all single amino acid mutations in TEM-1 at a clinically relevant dosage of ampicillin. The method should be easily extendable to other proteins for which a high-throughput selection assay is in place.

We present a protocol for the functional assessment of comprehensive single-site saturation mutagenesis libraries of proteins utilizing high-throughput sequencing. Importantly, this approach uses orthogonal primer pairs to multiplex library construction and sequencing. Representative results using TEM-1 &#946;-lactamase selected at a clinically relevant dosage of ampicillin are provided.

Site-directed mutagenesis has long been used as a method to interrogate protein structure, function and evolution. Recent advances in massively-parallel ...

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 ...