Name: mosquito-associated virus isolation from field-collected mosquitoes
Uploaded: 2022-08-31T13:20:00
Description: Watch this Scientific Journal Video about Mosquito-Associated Virus Isolation from Field-Collected Mosquitoes at JoVE.com

This work was supported by the Wuhan Science and Technology Plan Project (2018201261638501).

1. Mosquito sampling and sorting
<ol>
	<li>Trap the adult mosquitoes through the light traps MXA-02 or carbon dioxide mosquito traps in the field.</li>
	<li>Kill the collected mosquitoes by dipping in liquid nitrogen10,11. Transport them to the laboratory by the cold-chain logistics system12. 
	NOTE: Dry ice was primarily used in the cold-chain logistics system.</li>
	<li>(Optional) If the sample sites were near the...

<ol>
	<li>Xia, H., Wang, Y., Atoni, E., Zhang, B., Yuan, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mosquito-associated+viruses+in+China.">Mosquito-associated viruses in China.</a> Virologica Sinica. 33 (1), 5-20 (2018).</li><li>Atoni, E., 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=A+dataset+of+distribution+and+diversity+of+mosquito-associated+viruses+and+their+mosquito+vectors+in+China.">A dataset of distribution and diversity of mosquito-associated viruses and their mosquito vectors in China.</a> Scientific Data. 7 (1), 342 (2020).</li><li>Atoni, E., 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+discovery+and+global+distribution+of+novel+mosquito-associated+viruses+in+the+last+decade+(2007-2017).">The discovery and global distribution of novel mosquito-associated viruses in the last decade (2007-2017).</a> Reviews in Medical Virology. 29 (6), 2079 (2019).</li><li>Xia, 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=Comparative+metagenomic+profiling+of+viromes+associated+with+four+common+mosquito+species+in+China.">Comparative metagenomic profiling of viromes associated with four common mosquito species in China.</a> Virologica Sinica. 33 (1), 59-66 (2018).</li><li>Ong, O. T. W., Skinner, E. B., Johnson, B. J., Old, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mosquito-borne+viruses+and+non-human+vertebrates+in+Australia:+A+review.">Mosquito-borne viruses and non-human vertebrates in Australia: A review.</a> Viruses. 13 (2), 265 (2021).</li><li>Agboli, E., Leggewie, M., Altinli, M., Schnettler, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mosquito-specific+viruses-transmission+and+interaction.">Mosquito-specific viruses-transmission and interaction.</a> Viruses. 11 (9), 873 (2019).</li><li>Halbach, R., Junglen, S., van Rij, R. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mosquito-specific+and+mosquito-borne+viruses:+evolution,+infection,+and+host+defense.">Mosquito-specific and mosquito-borne viruses: evolution, infection, and host defense.</a> Current Opinion in Insect Science. 22, 16-27 (2017).</li><li>Bolling, B. G., Olea-Popelka, F. J., Eisen, L., Moore, C. G., Blair, C. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transmission+dynamics+of+an+insect-specific+flavivirus+in+a+naturally+infected+Culex+pipiens+laboratory+colony+and+effects+of+co-infection+on+vector+competence+for+West+Nile+virus.">Transmission dynamics of an insect-specific flavivirus in a naturally infected Culex pipiens laboratory colony and effects of co-infection on vector competence for West Nile virus.</a> Virology. 427 (2), 90-97 (2012).</li><li>Baidaliuk, 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=Cell-fusing+agent+virus+reduces+arbovirus+dissemination+in+Aedes+aegypti+mosquitoes+in+vivo.">Cell-fusing agent virus reduces arbovirus dissemination in Aedes aegypti mosquitoes in vivo.</a> Journal of Virology. 93 (18), 00715-00719 (2019).</li><li>Atoni, E., 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=Metagenomic+virome+analysis+of+Culex+mosquitoes+from+Kenya+and+China.">Metagenomic virome analysis of Culex mosquitoes from Kenya and China.</a> Viruses. 10 (1), 30 (2018).</li><li>Xia, 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=First+isolation+and+characterization+of+a+group+C+Banna+virus+(BAV)+from+Anopheles+sinensis+mosquitoes+in+Hubei,+China.">First isolation and characterization of a group C Banna virus (BAV) from Anopheles sinensis mosquitoes in Hubei, China.</a> Viruses. 10 (10), 555 (2018).</li><li>Shi, 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=Stability+of+the+virome+in+lab-+and+field-collected+Aedes+albopictus+mosquitoes+across+different+developmental+stages+and+possible+core+viruses+in+the+publicly+available+virome+data+of+Aedes+mosquitoes.">Stability of the virome in lab- and field-collected Aedes albopictus mosquitoes across different developmental stages and possible core viruses in the publicly available virome data of Aedes mosquitoes.</a> mSystems. 5 (5), 00640 (2020).</li><li>Zhou, M., Chu, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Handbook for Classification and Identification of Main Vectors. , (2019).</li><li>Wang, 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=Identifying+the+main+mosquito+species+in+China+based+on+DNA+barcoding.">Identifying the main mosquito species in China based on DNA barcoding.</a> Plos One. 7 (10), (2012).</li><li>Ratnasingham, S., Hebert, P. D. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bold:+The+Barcode+of+Life+Data+System+(www.barcodinglife.org).">Bold: The Barcode of Life Data System (www.barcodinglife.org).</a> Molecular Ecology Notes. 7 (3), 355-364 (2007).</li><li>Huang, 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=In+vitro+and+in+vivo+characterization+of+a+new+strain+of+mosquito+Flavivirus+derived+from+Culicoides.">In vitro and in vivo characterization of a new strain of mosquito Flavivirus derived from Culicoides.</a> Viruses. 14 (6), 1298 (2022).</li><li>Zhao, L., 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=Characterization+of+a+novel+Tanay+virus+isolated+from+Anopheles+sinensis+mosquitoes+in+Yunnan,+China.">Characterization of a novel Tanay virus isolated from Anopheles sinensis mosquitoes in Yunnan, China.</a> Frontiers in Microbiology. 10, 1963 (1963).</li><li>Ren, N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+of+a+novel+reassortment+Tibet+orbivirus+isolated+from+Culicoides+spp.+in+Yunnan,+PR+China.">Characterization of a novel reassortment Tibet orbivirus isolated from Culicoides spp. in Yunnan, PR China.</a> Journal of General Virology. 102 (9), 001645 (2021).</li></ol>

The objective of this method was to offer a practical way for isolating mosquito-associated viruses using various cell lines. It is critical to add the Antibiotic-Antimycotic (Penicillin-Streptomycin-Amphotericin) to the supernatants of the mosquito homogenates to avoid contamination by bacteria or fungi. Mosquitoes and viral supernatants obtained in the field must be refrigerated at -80 &#176;C to avoid repeated freeze-thaw cycles.
Another critical step in the protocol was grinding. Mosquito ...

Mosquitoes are a group of important pathogenic arthropod vectors. There are approximately 3,500 species of mosquitoes in the family Culicidae1,2. The development of high-throughput sequencing technologies has led to the discovery of many novel, virus-like sequences in mosquitoes from different parts of the world3. Generally, these mosquito-associated viruses can be classified into two main groups: MBVs and MSVs.
MBVs are a group of diverse viruses that are causative agents of many human or animal illnesses, such as yellow fever virus (YFV), dengue virus (DENV), Japanese encephalitis virus (JEV), West Nile virus (WNV), and Rift Valley fever virus (RVFV)4. They have seriously threatened public health by causing severe morbidity and mortality in both humans and animals across the world. MBVs naturally sustain a life cycle between diverse hosts through transmission from an infected mosquito to a na&#239;ve host, as well as from a virus-infected host and to a feeding mosquito5. Therefore, these viruses can infect both mosquito cell lines and vertebrate cell lines in the lab1.
MSVs, which include Yichang virus (YCN), Culex flavivirus (CxFV), and Chaoyang virus (CHAOV), are a subgroup of insect-specific viruses1,6,7. In recent years, there has been a rise in the discovery of novel MSVs, and some of these MSVs have been found to have an impact on the transmission of MBVs. For example, CxFV, which can be a persistent infection in Culex pipiens, could suppress WNV replication at an early stage8. Another insect-specific flavivirus, cell-fusing agent virus (CFAV), has been found to inhibit the propagation of DENV and Zika virus (ZIKV) in Aedes aegypti mosquitoes9. Thus, this protocol is a useful approach for isolating mosquito-associated viruses and can help in further research into the distribution of pathogens related to mosquitoes and the control of mosquito-borne diseases.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>0.22 &#181;m membrane filter</td>
			<td>Millipore</td>
			<td>SLGP033RB</td>
			<td>Polymer films with specific pore ratings.To remove cell debris and bacteria.</td>
		</tr>
		<tr>
			<td>24-well plates</td>
			<td>CORNING</td>
			<td>3524</td>
			<td>Containers for cell</td>
		</tr>
		<tr>
			<td>75 cm2 flasks</td>
			<td>CORNING</td>
			<td>430641</td>
			<td>Containers for cell</td>
		</tr>
		<tr>
			<td>a sterile 2 mL tube with 3 mm ceramic beads</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Antibiotic-Antimycotic</td>
			<td>Gibco</td>
			<td>15240-062</td>
			<td>Antibiotic in the medium to prevent contamination from bacteria and fungi</td>
		</tr>
		<tr>
			<td>Automated nucleic acid extraction system</td>
			<td>NanoMagBio</td>
			<td>S-48</td>
			<td></td>
		</tr>
		<tr>
			<td>BHK-21 cells</td>
			<td>National Virus Resource Center, Wuhan Institute of Virology</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>C6/36 cells</td>
			<td>National Virus Resource Center, Wuhan Institute of Virology</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Centrifugal machine</td>
			<td>Himac</td>
			<td>CF16RN</td>
			<td>Instrument for centrifugation of mosquito samples</td>
		</tr>
		<tr>
			<td>CO2</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Dulbecco&#8217;s minimal essential medium (DMEM)</td>
			<td>Gibco</td>
			<td>C11995500BT</td>
			<td>medium for vertebrate cell lines</td>
		</tr>
		<tr>
			<td>Ebinur Lake virus</td>
			<td></td>
			<td></td>
			<td>Cu20-XJ isolation</td>
		</tr>
		<tr>
			<td>Feta Bovine Serum (FBS)</td>
			<td>Gibco</td>
			<td>10099141C</td>
			<td> 
			 
			Provide nutrition for cells</td>
		</tr>
		<tr>
			<td>high-speed low-temperature tissue homogenizer</td>
			<td>servicebio</td>
			<td>KZ-III-F</td>
			<td>Instrument for grinding</td>
		</tr>
		<tr>
			<td>incubator (28 &#176;C)</td>
			<td>Panasonic</td>
			<td>MCO-18AC</td>
			<td>Instrument for cell culture</td>
		</tr>
		<tr>
			<td>incubator (37 &#176;C)</td>
			<td>Panasonic</td>
			<td>MCO-18AC</td>
			<td>Instrument for cell culture</td>
		</tr>
		<tr>
			<td>PCR tube</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>penicillin-streptomycin</td>
			<td>Gibco</td>
			<td>15410-122</td>
			<td>Antibiotic in the medium to prevent contamination from bacteria</td>
		</tr>
		<tr>
			<td>Penicillin-Streptomycin-Amphotericin B Solution</td>
			<td>Gibco</td>
			<td>15240096</td>
			<td></td>
		</tr>
		<tr>
			<td>Refrigerator (-80 &#176;C)</td>
			<td>sanyo</td>
			<td>MDF-U54V</td>
			<td></td>
		</tr>
		<tr>
			<td>Roswell Park Memorial Institute&#160; medium (RPMI)</td>
			<td>Gibco</td>
			<td>C11875500BT</td>
			<td>medium for mosiquto cell lines</td>
		</tr>
		<tr>
			<td>Screw cap storage tubes (2 mL)</td>
			<td>biofil</td>
			<td>&#160;FCT010005</td>
			<td></td>
		</tr>
		<tr>
			<td>sterile pestles</td>
			<td>Tiangen</td>
			<td>OSE-Y004</td>
			<td>Consumables&#160; for grinding</td>
		</tr>
		<tr>
			<td>TGrinder OSE-Y30 electric tissue grinder</td>
			<td>Tiangen</td>
			<td>OSE-Y30</td>
			<td>Instrument for grinding</td>
		</tr>
		<tr>
			<td>The dissecting microscope</td>
			<td>ZEISS</td>
			<td>stemi508</td>
			<td></td>
		</tr>
		<tr>
			<td>the light traps MXA-02</td>
			<td>Maxttrac</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>The mosquito absorbing machine</td>
			<td>Ningbo Bangning</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>The pipette tips</td>
			<td>Axygen</td>
			<td>TF</td>
			<td></td>
		</tr>
		<tr>
			<td>The QIAamp viral RNA mini kit</td>
			<td>QIAGEN</td>
			<td>52906</td>
			<td></td>
		</tr>
		<tr>
			<td>Tweezers</td>
			<td>Dumont</td>
			<td>0203-5-PO</td>
			<td></td>
		</tr>
	</tbody>
</table>

mosquito-associated virus isolation from field-collected mosquitoes

With the broad application of sequencing technologies, many novel virus-like sequences have been discovered in arthropods, including mosquitoes. The two main categories of these new mosquito-associated viruses are &#34;mosquito-borne viruses (MBVs)&#34; and &#34;mosquito-specific viruses (MSVs)&#34;. These novel viruses might be pathogenic to both vertebrates and mosquitoes, or they could just be symbiotic with mosquitoes. Entity viruses are essential to confirm the biological characters of these viruses. Thus, a detailed protocol has been described here for virus isolation and amplification from field-collected mosquitoes. First, the mosquito samples were prepared as supernatants of mosquito homogenates. After centrifugation twice, the supernatants were then inoculated into either mosquito cell line C6/36 or vertebrate cell line BHK-21 for virus amplification. After 7 days, the supernatants were collected as the P1 supernatants and stored at -80 &#176;C. Next, P1 supernatants were passaged twice more in C6/36 or BHK-21 cells while the cell status was being checked daily. When cytopathogenic effect (CPE) on the cells was discovered, these supernatants were collected and used to identify viruses. This protocol serves as the foundation for future research on mosquito-associated viruses, including MBVs and MSVs.

After inoculation with the supernatants of the mosquito homogenates (P0), the C6/36 cells exhibited a wide intercellular space, and exfoliated cells were observed at 120 h (Figure 1A) compared to the uninoculated cells (control) at the same time (Figure 1B). After incubating the BHK-21 cells with the P3 supernatants, visible CPE was observed in the BHK-21 cells at 48 h (Figure 1C) in contrast to the control cells (<strong class="xfi...

Watch this Scientific Journal Video about Mosquito-Associated Virus Isolation from Field-Collected Mosquitoes at JoVE.com

Mosquito-Associated Virus Isolation from Field-Collected Mosquitoes

Numerous novel virus-like sequences have been found in mosquitoes due to the extensive use of sequencing technologies. We provide an effective procedure for isolating and amplifying viruses using vertebrate and mosquito cell lines, which might serve as the basis for future studies on mosquito-associated viruses, including mosquito-borne and mosquito-specific viruses.

With the broad application of sequencing technologies, many novel virus-like sequences have been discovered in arthropods, including mosquitoes. The two ...

This protocol is a useful approach for isolating mosquito-associated viruses and can help in further research into the distribution of pathogens related to mosquitoes and the control of mosquito-borne diseases. Using thin lines to isolate viruses in Biosafety level 2 laboratory is safer and more efficient. Unlike other virus isolation procedures, such as cycling red inoculation with varying fluid, this technique does not necessitate animal experimentation or ethical assessment.The contamination from samples and the cells drawing during the incubation can lead to the failure of the experiment. Hence, it is necessary to add 2%Penicillin-Streptomycin-Amphotericin into the medium to prevent contamination. Begin with the addition of three-millimeter ceramic beads, 1.5 milliliters of RPMI medium supplemented with 2%Penicillin-Streptomycin-Amphotericin B Solution in a two-milliliter sterile tube placed on ice and then transfer 50 mosquitoes in it.Next, homogenize the mosquitoes with a low temperature tissue homogenizer by grinding for 30 seconds at 70 hertz and 4 degrees Celsius for 3 cycles. Centrifuge the homogenate at 15, 000 G for 30 minutes at 4 degrees Celsius and transfer the supernatants to the new tubes. To remove the mosquito debris completely, centrifuge the supernatant again at 15, 000 G for 10 minutes at 4 degrees Celsius.Aliquot the 200 microliters of supernatant P0 into a two-milliliter screw cap storage tube, and store it at minus 80 degrees Celsius. For the virus amplification, use Aedes albopictus RNAi-deficient mosquito cell line C6/36 and a vertebrate cell line, baby hamster kidney, or BHK-21 from a 75-centimeter square flask and seed them in 24 well plates separately. Place the seeded 24 well plate overnight at 28 or 37 degrees Celsius.The next day, observe the cells under the microscope to confirm 80 to 90%confluency in each well. Prepare 500 milliliters of the cell culture maintenance medium supplemented with antibiotics. Remove the cell culture medium from the 24 well plates and add 100 microliters of the cell culture maintenance medium to each well.Then inoculate the cells with 100 microliters of the supernatant of the mosquito homogenate or P0.Incubate the plates at 28 or 37 degrees Celsius for 60 minutes and gently shake the plates after every 15 minutes to prevent the drying of the cells. Once done, remove the supernatant and rinse each well with 600 microliters of cell culture maintenance medium to remove the debris completely. Next, add 800 microliters of cell culture maintenance medium to each well before placing the plates in a 5%carbon dioxide humidified incubator at 28 or 37 degrees Celsius for 7 days.Daily monitor the state of the cells of each well under the microscope. On the seventh day, collect the supernatant of cells known as P1 and store it at minus 80 degrees Celsius. Repeat the procedure to collect P2 and P3 viral supernatants.Due to the cytopathogenic effect, or CPE, cells from some of the wells die and detach from the surface. To greatly amplify the viruses Collect 300 to 400 microliters of the supernatant from wells showing the CPE effect and transfer it to a new six-well plate having 80 to 90%cell confluency of culture cells. Finally, collect and transfer 500 microliters of the supernatant from the wells of the six-well plate to two-milliliter screw cap storage tubes before storing them at minus 80 degrees Celsius.The inoculation of C6/36 cells with the mosquito homogenates P0 exhibited a wide intercellular space in exfoliated cells at 120 hours post-infection period compared to the uninoculated or control cells. Incubation of BHK21 cells with the P3 viral supernatants demonstrated a visible CPE at 48 hours post-infection, displaying the death of the cell and detachment from the surface in contrast to the control cells. Commercially available universal primers or Flaviviruses, Alphaviruses and Bunyaviruses were used to generate the PCR products for the viral supernatant.A PCR product for the Bunyavirus, Ebinur Lake virus, was set as a positive control. The PCR amplification bans in lanes belonging to Bunyaviruses and the positive control highlighted the possibility of the presence of Bunyavirus in the supernatants. To improve the success rate of virus isolation, keep a low temperature during sample transportation, isolation, and grinding.Add antibiotics when homogenizing the mosquitoes and the culture itself. And handle the culture rapidly during incubation and the removing the culture medium. In addition to this procedure, the grinding solution can be injected into a cycling rat or chicken embryo.However, the affirmation procedure will raise ethical concerns and increase the expense of the experiment.

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Dissection of Midgut and Salivary Glands from Ae. aegypti Mosquitoes

The mosquito midgut and salivary glands are key entry and exit points for pathogens such as Plasmodium parasites and Dengue viruses. This video protocol demonstrates dissection techniques for removal of the midgut and salivary glands from Aedes aegypti mosquitoes. 



The mosquito midgut and salivary glands are key entry and exit points for vector pathogens like Plasmodium falciparum and the dengue virus. This video demonstrates the dissection techniques for removing the midgut and salivary glands from Aedes aegypti mosquitoes.

The mosquito midgut and salivary glands are key entry and exit points for pathogens such as Plasmodium parasites and Dengue viruses. This video protocol ...

Isolation of Genomic DNA from Mouse Tails

Mitochondrial Isolation from Skeletal Muscle

Mitochondria are organelles controlling the life and death of the cell. They participate in key metabolic reactions, synthesize most of the ATP, and regulate a number of signaling cascades2,3. Past and current researchers have isolated mitochondria from rat and mice tissues such as liver, brain and heart4,5. In recent years, many researchers have focused on studying mitochondrial function from skeletal muscles.
Here, we describe a method that we have used successfully for the isolation of mitochondria from skeletal muscles 6. Our procedure requires that all buffers and reagents are made fresh and need about 250-500 mg of skeletal muscle. We studied mitochondria isolated from rat and mouse gastrocnemius and diaphragm, and rat extraocular muscles. Mitochondrial protein concentration is measured with the Bradford assay. It is important that mitochondrial samples be kept ice-cold during preparation and that functional studies be performed within a relatively short time (~1 hr). Mitochondrial respiration is measured using polarography with a Clark-type electrode (Oxygraph system) at 37&deg;C7. Calibration of the oxygen electrode is a key step in this protocol and it must be performed daily. Isolated mitochondria (150 &mu;g) are added to 0.5 ml of experimental buffer (EB). State 2 respiration starts with addition of glutamate (5mM) and malate (2.5 mM). Then, adenosine diphosphate (ADP) (150 &mu;M) is added to start state 3. Oligomycin (1 &mu;M), an ATPase synthase blocker, is used to estimate state 4. Lastly, carbonyl cyanide p-[trifluoromethoxy]-phenyl-hydrazone (FCCP, 0.2 &mu;M) is added to measurestate 5, or uncoupled respiration 6. The respiratory control ratio (RCR), the ratio of state 3 to state 4, is calculated after each experiment. An RCR &ge;4 is considered as evidence of a viable mitochondria preparation.
In summary, we present a method for the isolation of viable mitochondria from skeletal muscles that can be used in biochemical (e.g., enzyme activity, immunodetection, proteomics) and functional studies (mitochondrial respiration).

This protocol describes a procedure to study the respiration of mitochondria isolated from skeletal muscles. This method was adapted from Scorrano et al. (2007). The mitochondrial isolation procedure requires about 2 hours. The mitochondrial respiration can be completed in about 1 hour.

Mitochondria are organelles controlling the life and death of the cell. They participate in key metabolic reactions, synthesize most of the ATP, and ...

Isolation of Immune Cells from Primary Tumors

Tumors create a unique immunosuppressive microenvironment (tumor microenvironment, TME) whereby leukocytes are recruited into the tumor by various chemokines and growth factors 1,2. However, once in the TME, these cells lose the ability to promote anti-tumor immunity and begin to support tumor growth and down-regulate anti-tumor immune responses 3-4. Studies on tumor-associated leukocytes have mainly focused on cells isolated from tumor-draining lymph nodes or spleen due to the inherent difficulties in obtaining sufficient cell numbers and purity from the primary tumor. While identifying the mechanisms of cell activation and trafficking through the lymphatic system of tumor bearing mice is important and may give insight to the kinetics of immune responses to cancer, in our experience, many leukocytes, including dendritic cells (DCs), in tumor-draining lymph nodes have a different phenotype than those that infiltrate tumors 5,6 . Furthermore, we have previously demonstrated that adoptively-transferred T cells isolated from the tumor-draining lymph nodes are not tolerized and are capable of responding to secondary stimulation in vitro unlike T cells isolated from the TME, which are tolerized and incapable of proliferation or cytokine production 7,8. Interestingly, we have shown that changing the tumor microenvironment, such as providing CD4+ T helper cells via adoptive transfer, promotes CD8+ T cells to maintain pro-inflammatory effector functions 5. The results from each of the previously mentioned studies demonstrate the importance of measuring cellular responses from TME-infiltrating immune cells as opposed to cells that remain in the periphery. To study the function of immune cells which infiltrate tumors using the Miltenyi Biotech isolation system9, we have modified and optimized this antibody-based isolation procedure to obtain highly enriched populations of antigen presenting cells and tumor antigen-specific cytotoxic T lymphocytes. The protocol includes a detailed dissection of murine prostate tissue from a spontaneous prostate tumor model (TRansgenic Adenocarcinoma of the Mouse Prostate -TRAMP) 10 and a subcutaneous melanoma (B16) tumor model followed by subsequent purification of various leukocyte populations.

In this report, we describe a protocol for isolating highly purified populations of leukocytes that infiltrate tumors. This protocol is adapted from the Miltenyi Biotech protocol to enhance yield and purity for isolating cells from complex tumor tissue.

Tumors create a unique immunosuppressive microenvironment (tumor microenvironment, TME) whereby leukocytes are recruited into the tumor by various ...

The MultiBac Protein Complex Production Platform at the EMBL

Proteomics research revealed the impressive complexity of eukaryotic proteomes in unprecedented detail. It is now a commonly accepted notion that proteins in cells mostly exist not as isolated entities but exert their biological activity in association with many other proteins, in humans ten or more, forming assembly lines in the cell for most if not all vital functions.1,2 Knowledge of the function and architecture of these multiprotein assemblies requires their provision in superior quality and sufficient quantity for detailed analysis. The paucity of many protein complexes in cells, in particular in eukaryotes, prohibits their extraction from native sources, and necessitates recombinant production. The baculovirus expression vector system (BEVS) has proven to be particularly useful for producing eukaryotic proteins, the activity of which often relies on post-translational processing that other commonly used expression systems often cannot support.3 BEVS use a recombinant baculovirus into which the gene of interest was inserted to infect insect cell cultures which in turn produce the protein of choice. MultiBac is a BEVS that has been particularly tailored for the production of eukaryotic protein complexes that contain many subunits.4 A vital prerequisite for efficient production of proteins and their complexes are robust protocols for all steps involved in an expression experiment that ideally can be implemented as standard operating procedures (SOPs) and followed also by non-specialist users with comparative ease. The MultiBac platform at the European Molecular Biology Laboratory (EMBL) uses SOPs for all steps involved in a multiprotein complex expression experiment, starting from insertion of the genes into an engineered baculoviral genome optimized for heterologous protein production properties to small-scale analysis of the protein specimens produced.5-8 The platform is installed in an open-access mode at EMBL Grenoble and has supported many scientists from academia and industry to accelerate protein complex research projects.

Protein complexes catalyze key cellular functions. Detailed functional and structural characterization of many essential complexes requires recombinant production. MultiBac is a baculovirus/insect cell system particularly tailored for expressing eukaryotic proteins and their complexes. MultiBac was implemented as an open-access platform, and standard operating procedures developed to maximize its utility.

Proteomics  research revealed the impressive complexity of eukaryotic proteomes in  unprecedented detail. It is now a commonly accepted notion that ...

A Multi-detection Assay for Malaria Transmitting Mosquitoes

The Anopheles gambiae species complex includes the major malaria transmitting mosquitoes in Africa. Because these species are of such medical importance, several traits are typically characterized using molecular assays to aid in epidemiological studies. These traits include species identification, insecticide resistance, parasite infection status, and host preference. Since populations of the Anopheles gambiae complex are morphologically indistinguishable, a polymerase chain reaction (PCR) is traditionally used to identify species. Once the species is known, several downstream assays are routinely performed to elucidate further characteristics. For instance, mutations known as KDR in a para gene confer resistance against DDT and pyrethroid insecticides. Additionally, enzyme-linked immunosorbent assays (ELISAs) or Plasmodium parasite DNA detection PCR assays are used to detect parasites present in mosquito tissues. Lastly, a combination of PCR and restriction enzyme digests can be used to elucidate host preference (e.g., human vs. animal blood) by screening the mosquito bloodmeal for host-specific DNA. We have developed a multi-detection assay (MDA) that combines all of the aforementioned assays into a single multiplex reaction genotyping 33SNPs for 96 or 384 samples at a time. Because the MDA includes multiple markers for species, Plasmodium detection, and host blood identification, the likelihood of generating false positives or negatives is greatly reduced from previous assays that include only one marker per trait. This robust and simple assay can detect these key mosquito traits cost-effectively and in a fraction of the time of existing assays.

Malaria transmitting mosquitoes have a number of epidemiologically important characteristics that can only be detected using molecular techniques. Utilizing a MALDI-TOF based SNP genotyping platform, we developed an assay for simultaneously detecting multiple key traits (species, insecticide resistance, parasite infection and host choice) of malaria vectors.

The Anopheles gambiae species complex includes the major malaria transmitting mosquitoes in Africa. Because these species are of such medical importance, ...

Maintaining Aedes aegypti Mosquitoes Infected with Wolbachia

Aedes aegypti mosquitoes experimentally infected with Wolbachia are being utilized in programs to control the spread of arboviruses such as dengue, chikungunya and Zika. Wolbachia-infected mosquitoes can be released into the field to either reduce population sizes through incompatible matings or to transform populations with mosquitoes that are refractory to virus transmission. For these strategies to succeed, the mosquitoes released into the field from the laboratory must be competitive with native mosquitoes. However, maintaining mosquitoes in the laboratory can result in inbreeding, genetic drift and laboratory adaptation which can reduce their fitness in the field and may confound the results of experiments. To test the suitability of different Wolbachia infections for deployment in the field, it is necessary to maintain mosquitoes in a controlled laboratory environment across multiple generations. We describe a simple protocol for maintaining Ae. aegypti mosquitoes in the laboratory, which is suitable for both Wolbachia-infected and wild-type mosquitoes. The methods minimize laboratory adaptation and implement outcrossing to increase the relevance of experiments to field mosquitoes. Additionally, colonies are maintained under optimal conditions to maximize their fitness for open field releases.

Maintaining Aedes aegypti Mosquitoes Infected with Wolbachia

Aedes aegypti mosquitoes infected with Wolbachia are being released into natural populations to suppress the transmission of arboviruses. We describe methods to rear Ae. aegypti with Wolbachia infections in the laboratory for experiments and field release, taking precautions to minimize laboratory adaptation and selection.

Aedes aegypti mosquitoes experimentally infected with Wolbachia are being utilized in programs to control the spread of arboviruses such as dengue, ...

Isolation of High Quality Murine Atrial and Ventricular Myocytes for Simultaneous Measurements of Ca2+ Transients and L-Type Calcium Current

Mouse models play a crucial role in arrhythmia research and allow studying key mechanisms of arrhythmogenesis including altered ion channel function and calcium handling. For this purpose, atrial or ventricular cardiomyocytes of high quality are necessary to perform patch-clamp measurements or to explore calcium handling abnormalities. However, the limited yield of high-quality cardiomyocytes obtained by current isolation protocols does not allow both measurements in the same mouse. This article describes a method to isolate high-quality murine atrial and ventricular myocytes via retrograde enzyme-based Langendorff perfusion, for subsequent simultaneous measurements of calcium transients and L-type calcium current from one animal. Mouse hearts are obtained, and the aorta is rapidly cannulated to remove blood. Hearts are then initially perfused with a calcium-free solution (37 &#176;C) to dissociate the tissue at the level of intercalated discs and afterwards with an enzyme solution containing little calcium to disrupt extracellular matrix (37 &#176;C). The digested heart is subsequently dissected into atria and ventricles. Tissue samples are chopped into small pieces and dissolved by carefully pipetting up and down. The enzymatic digestion is stopped, and cells are stepwise reintroduced to physiologic calcium concentrations. After loading with a fluorescent Ca2+-indicator, isolated cardiomyocytes are prepared for simultaneous measurement of calcium currents and transients. Additionally, isolation pitfalls are discussed and patch-clamp protocols and representative traces of L-type calcium currents with simultaneous calcium transient measurements in atrial and ventricular murine myocytes isolated as described above are provided.

Isolation of High Quality Murine Atrial and Ventricular Myocytes for Simultaneous Measurements of Ca2+ Transients and L-Type Calcium Current

Mouse models allow studying key mechanisms of arrhythmogenesis. For this purpose, high quality cardiomyocytes are necessary to perform patch-clamp measurements. Here, a method to isolate murine atrial and ventricular myocytes via retrograde enzyme-based Langendorff perfusion, which allows simultaneous measurements of calcium-transients and L-type calcium current, is described.

Mouse models play a crucial role in arrhythmia research and allow studying key mechanisms of arrhythmogenesis including altered ion channel function and ...

Chromatin Extraction from Frozen Chimeric Liver Tissue for Chromatin Immunoprecipitation Analysis

Crosslinking Chromatin Immunoprecipitation (X-ChIP) is a widely used technique to assess levels of histone marks and occupancy of transcription factors on host and/or pathogen chromatin. Chromatin preparation from tissues creates additional challenges that need to be overcome to obtain reproducible and reliable protocols comparable to those used for cell culture. Tissue disruption and fixation are critical steps to achieve efficient shearing of chromatin. Coexistence of different cell types and clusters may also require different shearing times to reach optimal fragment size and hinders shearing reproducibility. The purpose of this method is to achieve reliable and reproducible host chromatin preparations from frozen tissue (liver) suitable for both ChIP-qPCR and next generation sequencing (NGS) applications. We observed that the combination of liquid nitrogen tissue pulverization followed by homogenization leads to increased reproducibility compared to homogenization only, since it provides a suspension consisting mostly of dissociated single cells that can be efficiently sheared. Moreover, the fixation step should be performed under mild rotation to provide homogeneous crosslinking. The fixed material is then suitable for buffer-based nuclei isolation, to reduce contamination of cytoplasmic protein and pathogen DNAs and RNAs (when applicable), avoiding time-consuming centrifugation gradients. Subsequent sonication will complete nuclear lysis and shear the chromatin, producing a specific size range according to the chosen shearing conditions. The size range should fall between 100 and 300 nt for NGS applications, while it could be higher (300-700 nt) for ChIP-qPCR analysis. Such protocol adaptations can greatly improve chromatin analyses from frozen tissue specimens.

This protocol focuses on chromatin preparation from snap frozen tissues and it is suitable for Crosslinking Chromatin Immunoprecipitation (X-ChIP) followed by either quantitative PCR analysis (X-ChIP-qPCR) or next generation sequencing approaches (X-ChIP-seq).

Crosslinking Chromatin Immunoprecipitation (X-ChIP) is a widely used technique to assess levels of histone marks and occupancy of transcription factors on ...

Dissection and Immunostaining of Larval Salivary Glands from Anopheles gambiae Mosquitoes

Mosquito salivary glands (SGs) are a requisite gateway organ for the transmission of insect-borne pathogens. Disease-causing agents, including viruses and the Plasmodium parasites that cause malaria, accumulate in the secretory cavities of SG cells. Here, they are poised for transmission to their vertebrate hosts during a subsequent blood meal. As adult glands form as an elaboration of larval SG duct bud remnants that persist beyond early pupal SG histolysis, the larval SG is an ideal target for interventions that limit disease transmission. Understanding larval SG development can help develop a better understanding of its morphology and functional adaptations and aid in the assessment of new interventions that target this organ. This video protocol demonstrates an efficient technique for isolating, fixing, and staining larval SGs from Anopheles gambiae mosquitoes. Glands dissected from larvae in a 25% ethanol solution are fixed in a methanol-glacial acetic acid mixture, followed by a cold acetone wash. After a few rinses in phosphate-buffered saline (PBS), SGs can be stained with a broad array of marker dyes and/or antisera against SG-expressed proteins. This method for larval SG isolation could also be used to collect tissue for in situ hybridization analysis, other transcriptomic applications, and proteomic studies.

Dissection and Immunostaining of Larval Salivary Glands from Anopheles gambiae Mosquitoes

The adult mosquito salivary gland (SG) is required for the transmission of all mosquito-borne pathogens to their human hosts, including viruses and parasites. This video demonstrates efficient isolation of the SGs from the larval (L4) stage Anopheles gambiae mosquitoes and preparation of the L4 SGs for further analysis.

Mosquito salivary glands (SGs) are a requisite gateway organ for the transmission of insect-borne pathogens. Disease-causing agents, including viruses and ...