This research was supported by Basic Science Research program (Project number: 2016R1A2B4013467) through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT &#38; Future Planning 2016 and also supported by Korea Basic Science Institute Research Program (Project number: C36707).

1. Synthesis of DMMTAV
<ol>
	<li>Chemical preparation and molar ratio mixing of DMAV, Na2S, and H2SO4 
	NOTE: DMAV:Na2S:H2SO4 = 1:1.6:1.6
	<ol>
		<li>Dissolve 5.24 g of DMAV in 40 mL deionized and N2-purged (purged for at least 30 min) water in a 50 mL centrifuge tube.</li>
		<li>Prepare Na2S reagent by dissolving 14.41 g of Na2S&#183;9H2O in 50 mL deionized and N2-purged water in a 250 mL flask.</li>
		<li>Prepare H2SO4 reagent by adding 3.3 mL of concentrated sulfuric acid (96%) to 40 mL of deionized and N2-purged water in a 50 mL centrifuge tube. 
		NOTE: Final molar ratio of DMAV:Na2S:H2SO4 = 1:1.6:1.6 1,3,4,8,15.</li>
		<li>Add the prepared 40 mL of DMAV solution (step 1.1.1) to the 50 mL of Na2S solution contained in the 250 mL flask (step 1.1.2). Rinse the tube containing DMAV with 10 mL of purged water and add this to the 250 mL flask as well.</li>
		<li>Close the flask with a three-hole rubber stopper fitted with glass tubes. Use the glass tubes for N2 gas inflow, outflow, and H2SO4 solution inlet, respectively. Immediately after closing the flask, allow N2 gas flow into the flask. 
		NOTE: Gas pressure should be maintained to flow over the surface of the reaction solution without splashing.</li>
		<li>Connect acid resistant tubing to the glass tube of the H2SO4 solution inlet with a 50 mL syringe to add the prepared 40 mL of H2SO4 solution (step 1.1.3). Add 40 mL of H2SO4 solution, slowly and in a stepwise manner. 
		Caution: Upon adding sulfuric acid, white fumes will be generated; use a well-ventilated fume hood.</li>
		<li>Monitor color change of the reaction mixture in the flask while adding sulfuric acid at regular intervals. Maintain an interval of 4 - 5 mL drops of H2SO4; the mixture should be a white cloudy solution. 
		NOTE: Instantaneous yellow precipitation might appear due to rapid addition of concentrated sulfuric acid.</li>
		<li>Ensure the reaction solution has been standing for 1 h since the start of step 1.1.4.</li>
	</ol>
	</li>
	<li>DMMTAV extraction using liquid-liquid extraction method
	<ol>
		<li>After 1 h, pour the reaction solution into a separatory funnel containing around 200 mL of diethyl ether.</li>
		<li>Shake the funnel for 5 - 10 min, releasing gas several times by switching the stopcock. 
		NOTE: Synthesized DMMTAV will be transferred to the upper layer of diethyl ether (0.713 g&#183;mL-1). 
		Caution: Diethyl ether gas might be harmful; use a well-ventilated fume hood.</li>
		<li>Collect the reaction solution in a beaker, and separately collect the diethyl ether containing DMMTAV in a bottle. Place the reaction solution back in the same separatory funnel and add about 200 mL of fresh diethyl ether for reshaking. Repeat steps 1.2.2 - 1.2.3 three times.</li>
		<li>Pour the collected diethyl ether from step 1.2.3 into the same separatory funnel again, and add about 100 mL N2-purged deionized water. Shake for 5 - 10 min, and discard the N2-purged deionized water and a few mL of diethyl ether for purity purposes. Collect the remaining diethyl ether in a glass petri dish (minimum inner diameter of 160 mm and minimum height of 50 mm).</li>
		<li>Transfer the glass petri dish into a N2 atmosphere glove box to prevent species transformation. 
		Caution: Ensure the solvent is not pulled into the vacuum pump through the outlet of the pass box.</li>
		<li>Dry until a white precipitate of dimethylmonothioarsinate (crystalized DMMTAV) is formed on the glass petri dish. 
		NOTE: The protocol can be paused here.</li>
	</ol>
	</li>
	<li>Verification of synthesized DMMTAV and storage
	<ol>
		<li>Take the white precipitate of crystalized DMMTAV, and measure and record its total weight. 
		Caution: Use a well ventilated fume hood or glove box to prevent inhalation of hydrogen sulfide gas.</li>
		<li>Dissolve crystalized DMMTAV in 50 mL of N2-purged deionized water, and filter the yellow precipitate through a 0.2-&#181;m syringe filter.</li>
		<li>Assume the total As of used DMAV is converted into DMMTAV, i.e.&#8776;9,649 mg As&#183;L-1. Dilute DMMTAV stock solution to &#8776;1 mg&#183;L-1 and &#8776;40 &#181;g&#183;L-1 for verification analysis using Electrospray ionization Mass Spectromtery (ESI-MS) and HPLC-ICP-MS, respectively.</li>
		<li>Analyze m/z of DMMTAV using ESI-MS11,16 and fragments at m/z 155 in the positive-ion mode or at m/z 153 in the negative-ion mode (Table 1). 
		NOTE: See reference values of m/z (Table 1).</li>
		<li>Analyze chromatogram of DMMTAV in the stock solution using HPLC-ICP-MS11,16,17 with appropriate eluent conditions and confirm a major peak is found at the retention time described in the literature. 
		NOTE: Purity of synthesized DMMTAV should be calculated using the analysis results from step 1.3.5.</li>
		<li>Analyze the total arsenic concentration using ICP-MS after acid digestion11 and calculate the true DMMTAV concentration in synthesized DMMTAV stock solution using dilution factors and purity, as in the following equation: 
		Analyzed total As concentration (&#181;g&#183;L-1) &#183; Dilution factor &#183; Purity (%) = True DMMTAV concentration in DMMTAV stock solution (&#181;g&#183;L-1)</li>
		<li>Store DMMTAV stock solution at 4 &#176;C in the dark for further quantitative speciation analysis18.</li>
	</ol>
	</li>
</ol>
2. Synthesis of DMDTAV
<ol>
	<li>Chemical preparation and molar ratio mixing of DMAV , Na2S, and H2SO4 
	NOTE: DMAV:Na2S:H2SO4 = 1:7.5:7.5
	<ol>
		<li>Dissolve 1.38 g of DMAV in 40 mL deionized water in a 50 mL centrifuge tube.</li>
		<li>Prepare Na2S reagent by dissolving 18.01 g of Na2S&#183;9H2O in a 50 mL deionized water in a 250 mL flask.</li>
		<li>Prepare H2SO4 reagent by adding 4 mL of concentrated sulfuric acid (96%) to 40 mL of deionized water contained in a 50 mL centrifuge tube. 
		NOTE: Final molar ratio of DMAV:Na2S:H2SO4 = 1:7.5:7.51,3,4,8,15.</li>
		<li>Add the prepared 40 mL of DMAV solution (step 2.1.1) to the 50 mL of Na2S solution contained in the 250 mL flask (step 2.1.2). Rinse the tube containing DMAV with 10 mL of deionized water and add this to the 250 mL flask as well.</li>
		<li>Add the prepared 40 mL of H2SO4 solution (step 2.1.3), slowly and in a stepwise manner, into the flask.</li>
		<li>Monitor the color change of the reaction mixture in the flask while adding sulfuric acid at regular intervals. Maintain an interval of 4 - 5 mL drops of H2SO4; the mixture should be a white/yellow cloudy solution. 
		NOTE: Instantaneous yellow precipitation might appear due to a rapid addition of concentrated sulfuric acid. 
		Caution: Upon adding sulfuric acid, white fumes will be generated; use a well ventilated fume hood.</li>
		<li>Maintain the reaction solution in the flask overnight without covering. 
		NOTE: The protocol can be paused here.</li>
	</ol>
	</li>
	<li>DMDTAV extraction using solid-phase extraction (SPE) method
	<ol>
		<li>After the overnight standing reaction, filter the reaction solution using a C18 syringe type silica-based SPE in order to trap synthesized DMDTAV on the resin. 
		Caution: Use a well-ventilated fume hood.</li>
		<li>Prepare 10 mM ammonium acetate (pH 6.3) by dissolving 0.77 g ammonium acetate in 1 L of deionized water. Elute a sufficient volume of 10 mM ammonium acetate through the C18 syringe (step 2.2.1) to extract the adsorbed DMDTAV. Collect the filtered ammonium acetate in a glass Petri dish (minimum inner diameter of 160 mm and minimum height of 50 mm).</li>
		<li>Transfer the glass petri dish into a N2 atmosphere glove box to prevent species transformation. 
		Caution: Ensure solvent is not pulled into the vacuum pump through the outlet of the pass box.</li>
		<li>Dry until a white precipitate of dimethyldithioarsinate is formed (crystalized DMDTAV) on the glass petri dish. 
		NOTE: The protocol can be paused here.</li>
	</ol>
	</li>
	<li>Verification of synthesized DMDTAV and storage
	<ol>
		<li>Take the white precipitate of crystalized DMDTAV, and measure its total weight, recording the measurement. 
		Caution: Use a well-ventilated fume hood or glove box to prevent inhalation of hydrogen sulfide gas.</li>
		<li>Dissolve crystalized DMDTAV in 50 mL of N2-purged deionized water in a 50 mL centrifuge tube, and filter any precipitate through a 0.2-&#181;m syringe filter.</li>
		<li>Assume that the total As of used DMAV is converted into DMDTAV, i.e.&#8776;2,539 mg As&#183;L-1. Dilute DMDTAV stock solution to &#8776;1&#160;mg&#183;L-1 and &#8776;40 &#181;g&#183;L-1 for verification analysis using ESI-MS and HPLC-ICP-MS, respectively.</li>
		<li>Analyze m/z of DMDTAV using ESI-MS11,16 and fragments at m/z 171 in the positive-ion mode or at m/z 169 in the negative-ion mode (Table 1). 
		NOTE: See reference values of m/z (Table 1).</li>
		<li>Analyze the chromatogram of DMDTAV in the stock solution using HPLC-ICP-MS11,16,17 with appropriate eluent conditions and confirm that a peak is found at the retention time described in the literature. 
		NOTE: Purity of synthesized DMDTAV should be calculated using the analysis results from step 2.3.5.</li>
		<li>Analyze the total arsenic concentration using ICP-MS after acid digestion11 and calculate the true DMDTAV concentration in synthesized DMDTAV stock solution using dilution factors and purity as the following equation: 
		Analyzed total As concentration (&#181;g&#183;L-1) &#183; Dilution factor &#183; Purity (%) = True DMDTAV concentration of DMDTAV in stock solution (&#181;g&#183;L-1)</li>
		<li>Store DMDTAV stock solution at 4 &#176;C in the dark for further quantitative speciation analysis18.</li>
	</ol>
	</li>
</ol>

<ol>
	<li>Suzuki, K. T., 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=Dimethylthioarsenicals+as+arsenic+metabolites+and+their+chemical+preparation.">Dimethylthioarsenicals as arsenic metabolites and their chemical preparation.</a> Chem. Res. Toxicol. 17, 914-921 (2004).</li><li>Kuroda, 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=Microbial+metabolite+of+dimethylarsinic+acid+is+highly+toxic+and+genotoxic.">Microbial metabolite of dimethylarsinic acid is highly toxic and genotoxic.</a> Toxicol. Appl. Pharmacol. 198, 345-353 (2004).</li><li>Naranmandura, H., Iwata, K., Suzuki, K. T., Ogra, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Distribution+and+metabolism+of+four+different+dimethylated+arsenicals+in+hamsters.">Distribution and metabolism of four different dimethylated arsenicals in hamsters.</a> Toxicol. Appl. Pharmacol. 245, 67-75 (2010).</li><li>Naranmandura, 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+toxicity+of+arsenic+metabolites+in+human+bladder+cancer+EJ-1+cells.">Comparative toxicity of arsenic metabolites in human bladder cancer EJ-1 cells.</a> Chem. Res. Toxicol. 24, 1586-1596 (2011).</li><li>Wallschlager, D., London, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Determination+of+methylated+arsenic-sulfur+compounds+in+groundwater.">Determination of methylated arsenic-sulfur compounds in groundwater.</a> Environ. Sci. Technol. 42, 228-234 (2008).</li><li>Zhang, J., Kim, H., Townsend, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Methodology+for+assessing+thioarsenic+formation+potential+in+sulfidic+landfill+environments.">Methodology for assessing thioarsenic formation potential in sulfidic landfill environments.</a> Chemosphere. 107, 311-318 (2014).</li><li>Shimoda, 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=Proposal+for+novel+metabolic+pathway+of+highly+toxic+dimethylated+arsenics+accompanied+by+enzymatic+sulfuration,+desulfuration+and+oxidation.">Proposal for novel metabolic pathway of highly toxic dimethylated arsenics accompanied by enzymatic sulfuration, desulfuration and oxidation.</a> Trace Elem. Med. Biol. 30, 129-136 (2015).</li><li>Naranmandura, H., Suzuki, T. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Formation+of+dimethylthioarsenicals+in+red+blood+cells.">Formation of dimethylthioarsenicals in red blood cells.</a> Toxicol. Appl. Pharmacol. 227, 390-399 (2008).</li><li>Leffers, L., Ebert, F., Taleshi, S. M., Francesconi, A. K., Schwerdtle, T. <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+toxicological+characterization+of+two+arsenosugars+and+their+metabolites.">In vitro toxicological characterization of two arsenosugars and their metabolites.</a> Mol. Nutr. Food Res. 57, 1270-1282 (2013).</li><li>Wang, Q. Q., Thomas, J. D., Naranmandura, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Important+of+being+thiomethylated:+Formation,+Fate+and+Effects+of+methylated+thioarsenicals.">Important of being thiomethylated: Formation, Fate and Effects of methylated thioarsenicals.</a> Chem. Res. Toxicol. 25, 281-289 (2015).</li><li>Kim, Y. T., Lee, H., Yoon, H. O., Woo, N. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Kinetics+of+dimethylated+thioarsenicals+and+the+formation+of+highly+toxic+dimethylmonothioarsinic+acid+in+environment.">Kinetics of dimethylated thioarsenicals and the formation of highly toxic dimethylmonothioarsinic acid in environment.</a> Environ. Sci. Technol. 50, 11637-11645 (2016).</li><li>Cullen, W. R., 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=Methylated+and+thiolated+arsenic+species+for+environmental+and+health+research+-+A+review+on+synthesis+and+characterization.">Methylated and thiolated arsenic species for environmental and health research - A review on synthesis and characterization.</a> J. Environ. Sci. 49, 7-27 (2016).</li><li>Fricke, 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=Chromatographic+separation+and+identification+of+products+form+the+reaction+of+dimethylarsinic+acid+with+hydrogen+sulfide.">Chromatographic separation and identification of products form the reaction of dimethylarsinic acid with hydrogen sulfide.</a> Chem. Res. Toxicol. 18, 1821-1829 (2005).</li><li>Fricke, M., Zeller, M., Cullen, W., Witkowski, M., Creed, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dimethylthioarsinic+anhydride:+a+standard+for+arsenic+speciation.">Dimethylthioarsinic anhydride: a standard for arsenic speciation.</a> Anal. Chim. Acta. 583, 78-83 (2007).</li><li>Suzuki, K. T., Iwata, K., Naranmandura, H., Suzuki, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Metabolic+differences+between+twon+dimethylthioarsenicals+in+rats.">Metabolic differences between twon dimethylthioarsenicals in rats.</a> Toxicol. Appl. Pharmacol. 218, 166-173 (2007).</li><li>Jeong, S., 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=Development+of+a+simultaneous+analytical+method+to+determine+arsenic+speciation+using+HPLC-ICP-MS:+Arsenate,+arsenite,+monomethylarsonic+acid,+dimethylarsinic+acid,+dimethyldithioarsinic+acid,+and+dimethylmonothioarsinic+acid.">Development of a simultaneous analytical method to determine arsenic speciation using HPLC-ICP-MS: Arsenate, arsenite, monomethylarsonic acid, dimethylarsinic acid, dimethyldithioarsinic acid, and dimethylmonothioarsinic acid.</a> Microchem. J. 134, 295-300 (2017).</li><li>Li, Y., Low, C. -. K., Scott, A. J., Amal, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Arsenic+speciation+in+municipal+landfill+leachate.">Arsenic speciation in municipal landfill leachate.</a> Chemosphere. 79, 794-801 (2010).</li><li>Conklin, D. S., Fricke, W. M., Creed, A. P., Creed, J. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Investigation+of+the+pH+effects+on+the+formation+of+methylated+thio-arsenicals,+and+the+effects+of+pH+and+temperature+on+their+stability.">Investigation of the pH effects on the formation of methylated thio-arsenicals, and the effects of pH and temperature on their stability.</a> J. Anal. At. Spectrom. 23, 711-716 (2008).</li><li>Hansen, H. R., Raab, A., Jaspara, M., Milne, F. B., Feldmann, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sulfur-containing+arsenical+mistaken+for+dimethylarsinous+acid+[DMA(III)]+and+identified+as+a+natural+metabolite+in+urine:+major+implications+for+studies+on+arsenic+metabolism+and+toxicity.">Sulfur-containing arsenical mistaken for dimethylarsinous acid [DMA(III)] and identified as a natural metabolite in urine: major implications for studies on arsenic metabolism and toxicity.</a> Chem. Res. Toxicol. 17, 1086-1091 (2004).</li><li>Mandal, B. K., Suzuki, K. T., Anzai, K., Yamaguchi, K., Sei, 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+SEC-HPLC-ICP-MS+hyphenated+technique+for+identification+of+sulfur-containing+arsenic+metabolites+in+biological+samples.">A SEC-HPLC-ICP-MS hyphenated technique for identification of sulfur-containing arsenic metabolites in biological samples.</a> J. Chromatogr. B. 874, 64-76 (2008).</li><li>Bartel, M., Ebert, F., Leffers, L., Karst, U., Schwerdtle, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Toxicological+characterization+of+the+inorganic+and+organic+arsenic+metabolite+thio-DMAV+in+cultured+human+lung+cells.">Toxicological characterization of the inorganic and organic arsenic metabolite thio-DMAV in cultured human lung cells.</a> J. Toxicol. 2011, (2011).</li><li>An, 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=Formation+of+dimethyldithioarsinic+acid+in+a+simulated+landfill+leachate+in+relation+to+hydrosulfide+concentration.">Formation of dimethyldithioarsinic acid in a simulated landfill leachate in relation to hydrosulfide concentration.</a> Environ. Geochem. Health. 38, 255-263 (2016).</li><li>Chen, B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Arsenic+speciation+in+the+blood+of+arsenite-treated+F344+rats.">Arsenic speciation in the blood of arsenite-treated F344 rats.</a> Chem. Res. Toxicol. 26, 952-962 (2013).</li><li>Alava, P., 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=HPLC-ICP-MS+method+development+to+monitor+arsenic+speciation+changes+by+human+gut+microbiota.">HPLC-ICP-MS method development to monitor arsenic speciation changes by human gut microbiota.</a> Biomed. Chromatogr. 26, 524-533 (2012).</li><li>Kurosawa, 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=A+novel+metabolic+activation+associated+with+glutathione+in+dimethylmonoarsinic+acid+(DMMTAV)-induced+toxicity+obtained+from+in+vitro+reaction+of+DMMTAV+with+glutathione.">A novel metabolic activation associated with glutathione in dimethylmonoarsinic acid (DMMTAV)-induced toxicity obtained from in vitro reaction of DMMTAV with glutathione.</a> J. trace Elem. Med. Biol. 33, 87-94 (2016).</li></ol>

The authors have nothing to disclose.

The developed protocol has clarified critical steps that previous studies1,3,4,8,15 omitted or abbreviated, which may have led to difficulties with or failure during DMMTAV and DMDTAV synthesis. As DMMTAV is oxidation-sensitive1,5, chemical reagents for its synthesis we...

Since dimethylarsinic acid (DMAV) has been demonstrated to exhibit both acute toxicity and genotoxicity due to undergoing methylation and thiolation upon ingestion1,2, the metabolic pathway of arsenic thiolation has been intensively studied both in vitro and in vivo3,4 as well as in environmental media (e.g., landfill leachate)5,6. Previous studies have found both reduced and thiolated analogs of DMAV in living cells, for example, dimethylarsinous acid (DMAIII), dimethylmonothioarsinic acid (DMMTAV), and dimethyldithioarsinic acid (DMDTAV)7,8,9, with dimethylated thioarsenicals such as DMMTAV exhibiting greater toxicity than other known inorganic or organic arsenicals10. The abundance of highly toxic thioarsenicals has serious environmental implications, since they may pose a risk to humans and the environment under highly sulfidic conditions11. However, the mechanisms of DMMTAV and DMDTAV (trans)formation and their fates in environmental media still require further study. Thus, the quantitative analysis of thioarsenicals is required to improve understanding of the environmental effects of DMMTAV and DMDTAV.
Although standard chemicals are the key requirement for quantitative analysis, the standards of DMMTAV and DMDTAV are difficult to obtain by replicating previous studies, owing to the high risk of species transformation into other species and unstandardized synthesis procedures12. Moreover, the methods referenced have limitations that may lead to practical difficulties in synthesizing the standard chemicals and performing quantitative analysis. DMMTAV and DMDTAV are commonly prepared by mixing DMAV, Na2S, and H2SO4 in a certain molar ratio1 or bubbling H2S gas through a solution of DMAV 13,14. The bubbling method features substitution of oxygen by sulfur using a direct supply of H2S gas, which, is highly toxic and difficult to control for an inexperienced user. Conversely, the above mixing method1, widely used for the qualitative analysis of DMMTAV and DMDTAV in environmental sudies5,6,12, features the thiolation of DMAV with H2S generated by mixing Na2S and H2SO4 and produces DMMTAV and DMDTAV, allowing easier stoichiometric control to produce target chemicals, as compared to the direct use of H2S gas.
The reference mixing method procedures1,3,4,8,15 mentioned in this study exhibit limitations in some of their critical experimental steps, which might lead to experimental failure. For example, the details of specific solvent (i.e., deionized water) preparation and the extraction and crystallization of the synthesized arsenicals are over-abbreviated or not described in sufficient detail. Such dispersed and limited information on procedural steps might lead to the inconsistent formation of thioarsenicals and unreliable quantification analysis. Therefore, the modified protocol developed herein describes the synthesis of DMMTAV and DMDTAV stock solutions with quantitative species separation analysis.

<table><tbody><tr><td>Cacodylic acid</td><td>Sigma-Aldrich</td><td>20835-10G-F</td><td></td></tr><tr><td>Sodium sulfide nonahydrate</td><td>Sigma-Aldrich</td><td>S2006-500G</td><td></td></tr><tr><td>Sulfuric acid 96%</td><td>J.T.Baker</td><td>0000011478</td><td></td></tr><tr><td>Ammonium acetate</td><td>Sigma-Aldrich</td><td>A7262-500G</td><td></td></tr><tr><td>Formic acid 98%</td><td>Wako Pure Chemical Industries, Ltd.</td><td>066-00461</td><td></td></tr><tr><td>Diethyl ether (Extra Pure)</td><td>Junsei Chemical</td><td>33475-0380</td><td></td></tr><tr><td>Adapter cap for 60 mL Bond Elut catridges</td><td>Agilent Technologies</td><td>12131004</td><td>Syringe type of SPE</td></tr><tr><td>Bond Elut C18 cartridge</td><td>Agilent Technologies</td><td>14256031</td><td>Syringe type of SPE</td></tr><tr><td>HyPURITY C-18</td><td>Thermo Scientific</td><td>22105-254630</td><td>5 um, 125 x 4.6 mm</td></tr><tr><td>Glovebox</td><td>Chungae-chun, Rep. of Korea</td><td></td><td>Customized&amp;nbsp;</td></tr><tr><td>Agilent 1260 Infinity Bio-inert LC</td><td>Agilent Technologies</td><td>DEAB600252, DEACH00245</td><td></td></tr><tr><td>Agilent Technologies 7700 Series ICP-MS</td><td>Agilent Technologies</td><td>JP12031510</td><td></td></tr><tr><td>Finnigan LCQ Deca XP MAX Mass Spectrometer System</td><td>Thermo Electron Corporation</td><td>LDM10627</td><td></td></tr></tbody></table>

preparation of dmmtav and dmdtav using dmav for environmental applications: synthesis, purification, and confirmation

Dimethylated thioarsenicals such as dimethylmonothioarsinic acid (DMMTAV) and dimethyldithioarsinic acid (DMDTAV), which are produced by the metabolic pathway of dimethylarsinic acid (DMAV) thiolation, have been recently found in the environment as well as human organs. DMMTAV and DMDTAV can be quantified to determine the ecological effects of dimethylated thioarsenicals and their stability in environmental media. The synthesis method for these compounds is unstandardized, making replicating previous studies challenging. Furthermore, there is a lack of information about storage techniques, including storage of compounds without species transformation. Moreover, because only limited information about synthesis methods is available, there may be experimental difficulties in synthesizing standard chemicals and performing quantitative analysis. The protocol presented herein provides a practically modified synthesis method for the dimethylated thioarsenicals, DMMTAV and DMDTAV, and will help in the quantification of species separation analysis using high performance liquid chromatography in conjunction with inductively coupled plasma mass spectrometry (HPLC-ICP-MS). The experimental steps of this procedure were modified by focusing on the preparation of chemical reagents, filtration methods, and storage.

Since DMMTAV has been mistakenly prepared by the DMAIII synthesis method19, verification of synthesized DMMTAV and DMDTAV is a critical step for synthesis and extraction and determining the ideal standard chemical materials. Synthesized chemicals can be verified by the peak of DMMTAV (MW 154 g&#183;mol-1) and DMDTAV (MW 170 g&#183;mol-1) mass-to-charge ratio (m/z) using...

Watch this Scientific Journal Video about Preparation of DMMTAV and DMDTAV Using DMAV for Environmental Applications: Synthesis, Purification, and Confirmation at JoVE.com

Preparation of DMMTAV and DMDTAV Using DMAV for Environmental Applications: Synthesis, Purification, and Confirmation

This article presents modified experimental protocols for dimethylmonothioarsinic acid (DMMTAV) and dimethyldithioarsinic acid (DMDTAV) synthesis, inducing dimethylarsinic acid (DMAV) thiolation through mixing of DMAV, Na2S, and H2SO4. The modified protocol provides an experimental guideline, thereby overcoming limitations of the synthesis steps that could have caused experimental failures in quantitative analysis.

Preparation of DMMTAV and DMDTAV Using DMAV for Environmental Applications: Synthesis, Purification, and Confirmation

Dimethylated thioarsenicals such as dimethylmonothioarsinic acid (DMMTAV) and dimethyldithioarsinic acid (DMDTAV), which are produced by the metabolic ...

preparation-dmmtav-dmdtav-using-dmav-for-environmental-applications

Universidad de Cartagena UDEC

Research

JoVE Journal

Environment

5.5K Views.  Korea Basic Science Institute, Seoul Center. This article presents modified experimental protocols for dimethylmonothioarsinic acid (DMMTAV) and dimethyldithioarsinic acid (DMDTAV) synthesis, inducing dimethylarsinic acid (DMAV) thiolation through mixing of DMAV, Na2S, and H2SO4. The modified protocol provides an experimental guideline, thereby overcoming limitations of the synthesis steps that could have caused experimental failures in qua...

Video: Preparation of DMMTAV and DMDTAV Using DMAV for Environmental Applications: Synthesis, Purification, and Confirmation

Unraveling the Unseen Players in the Ocean - A Field Guide to Water Chemistry and Marine Microbiology

Here we introduce a series of thoroughly tested and well standardized research protocols adapted for use in remote marine environments. The sampling protocols include the assessment of resources available to the microbial community (dissolved organic carbon, particulate organic matter, inorganic nutrients), and a comprehensive description of the viral and bacterial communities (via direct viral and microbial counts, enumeration of autofluorescent microbes, and construction of viral and microbial metagenomes). We use a combination of methods, which represent a dispersed field of scientific disciplines comprising already established protocols and some of the most recent techniques developed. Especially metagenomic sequencing techniques used for viral and bacterial community characterization, have been established only in recent years, and are thus still subjected to constant improvement. This has led to a variety of sampling and sample processing procedures currently in use. The set of methods presented here provides an up to date approach to collect and process environmental samples. Parameters addressed with these protocols yield the minimum on information essential to characterize and understand the underlying mechanisms of viral and microbial community dynamics. It gives easy to follow guidelines to conduct comprehensive surveys and discusses critical steps and potential caveats pertinent to each technique.

Here, we present a comprehensive protocol to assess the organic and inorganic nutrient availability and the abundance and structure of microbial and viral communities in remote marine environments.

Here we introduce a series of thoroughly tested and well standardized research protocols adapted for use in remote marine environments. The sampling ...

In vitro tRNA Methylation Assay with the Entamoeba histolytica DNA and tRNA Methyltransferase Dnmt2 (Ehmeth) Enzyme

Protozoan parasites are among the most devastating infectious agents of humans responsible for a variety of diseases including amebiasis, which is one of the three most common causes of death from parasitic disease. The agent of amebiasis is the amoeba parasite Entamoeba histolytica that exists under two stages: the infective cyst found in food or water and the invasive trophozoite living in the intestine. The clinical manifestations of amebiasis range from being asymptomatic to colitis, dysentery or liver abscesses. E. histolytica is one of the rare unicellular parasite with 5-methylcytosine (5mC) in its genome. 1, 2 It contains a single DNA methyltransferase, Ehmeth, that belongs to the Dnmt2 family. 2 A role for Dnmt2 in the control of repetitive elements has been established in E. histolytica, 3 Dictyostelium discoideum 4,5 and Drosophila. 6 Our recent work has shown that Ehmeth methylates tRNAAsp, and this finding indicates that this enzyme has a dual DNA/tRNAAsp methyltransferase activity. 7 This observation is in agreement with the dual activity that has been reported for D. discoideum and D. melanogaster. 8 The functional significance of the DNA/tRNA specificity of Dnmt2 enzymes is still unknown. To address this question, a method to determine the tRNA methyltransferase activity of Dnmt2 proteins was established. In this video, we describe a straightforward approach to prepare an adequate tRNA substrate for Dnmt2 and a method to measure its tRNA methyltransferase activity.

In vitro tRNA Methylation Assay with the Entamoeba histolytica DNA and tRNA Methyltransferase Dnmt2 Ehmeth Enzyme

This protocol describes the preparation of a synthetic tRNA substrate for the Entamoeba histolytica DNA/tRNA methyltransferase 2 (Dnmt2) homolog Ehmeth and the measure of its methyltransferase activity. This experimental approach can be used for investigating the activity of other Dnmt2 proteins.

Protozoan parasites are among the most devastating infectious agents of humans responsible for a variety of diseases including amebiasis, which is one of ...

Immunology and Infection

Biochemical Measurement of Neonatal Hypoxia

Neonatal hypoxia ischemia is characterized by inadequate blood perfusion of a tissue or a systemic lack of oxygen. This condition is thought to cause/exacerbate well documented neonatal disorders including neurological impairment 1-3. Decreased adenosine triphosphate production occurs due to a lack of oxidative phosphorylation. To compensate for this energy deprived state molecules containing high energy phosphate bonds are degraded 2. This leads to increased levels of adenosine which is subsequently degraded to inosine, hypoxanthine, xanthine, and finally to uric acid. The final two steps in this degradation process are performed by xanthine oxidoreductase. This enzyme exists in the form of xanthine dehydrogenase under normoxic conditions but is converted to xanthine oxidase (XO) under hypoxia-reperfusion circumstances 4, 5. Unlike xanthine dehydrogenase, XO generates hydrogen peroxide as a byproduct of purine degradation 4, 6. This hydrogen peroxide in combination with other reactive oxygen species (ROS) produced during hypoxia, oxidizes uric acid to form allantoin and reacts with lipid membranes to generate malondialdehyde (MDA) 7-9. Most mammals, humans exempted, possess the enzyme uricase, which converts uric acid to allantoin. In humans, however, allantoin can only be formed by ROS-mediated oxidation of uric acid. Because of this, allantoin is considered to be a marker of oxidative stress in humans, but not in the mammals that have uricase.
We describe methods employing high pressure liquid chromatography (HPLC) and gas chromatography mass spectrometry (GCMS) to measure biochemical markers of neonatal hypoxia ischemia. Human blood is used for most tests. Animal blood may also be used while recognizing the potential for uricase-generated allantoin. Purine metabolites were linked to hypoxia as early as 1963 and the reliability of hypoxanthine, xanthine, and uric acid as biochemical indicators of neonatal hypoxia was validated by several investigators 10-13. The HPLC method used for the quantification of purine compounds is fast, reliable, and reproducible. The GC/MS method used for the quantification of allantoin, a relatively new marker of oxidative stress, was adapted from Gruber et al 7. This method avoids certain artifacts and requires low volumes of sample. Methods used for synthesis of MMDA were described elsewhere 14, 15. GC/MS based quantification of MDA was adapted from Paroni et al. and Cighetti et al. 16, 17. Xanthine oxidase activity was measured by HPLC by quantifying the conversion of pterin to isoxanthopterin 18. This approach proved to be sufficiently sensitive and reproducible.

A method is described to measure biochemical markers of neonatal hypoxia-ischemia. The approach utilizes high pressure liquid chromatography (HPLC) and Gas Chromatography Mass Spectrometry (GC/MS).

Neonatal hypoxia ischemia is characterized by inadequate blood perfusion of a tissue or a systemic lack of oxygen. This condition is thought to ...

Medicine

Cost-effective Method for Microbial Source Tracking Using Specific Human and Animal Viruses

Microbial contamination of the environment represents a significant health risk. Classical bacterial fecal indicators have shown to have significant limitations, viruses are more resistant to many inactivation processes and standard fecal indicators do not inform on the source of contamination. The development of cost-effective methods for the concentration of viruses from water and molecular assays facilitates the applicability of viruses as indicators of fecal contamination and as microbial source tracking (MST) tools. Adenoviruses and polyomaviruses are DNA viruses infecting specific vertebrate species including humans and are persistently excreted in feces and/or urine in all geographical areas studied. In previous studies, we suggested the quantification of human adenoviruses (HAdV) and JC polyomaviruses (JCPyV) by quantitative PCR (qPCR) as an index of human fecal contamination. Recently, we have developed qPCR assays for the specific quantification of porcine adenoviruses (PAdV) and bovine polyomaviruses (BPyV) as animal fecal markers of contamination with sensitivities of 1-10 genome copies per test tube. In this study, we present the procedure to be followed to identify the source of contamination in water samples using these tools. As example of representative results, analysis of viruses in ground water presenting high levels of nitrates is shown.
Detection of viruses in low or moderately polluted waters requires the concentration of the viruses from at least several liters of water into a much smaller volume, a procedure that usually includes two concentration steps in series. This somewhat cumbersome procedure and the variability observed in viral recoveries significantly hamper the simultaneous processing of a large number of water samples.
In order to eliminate the bottleneck caused by the two-step procedures we have applied a one-step protocol developed in previous studies and applicable to a diversity of water matrices. The procedure includes: acidification of ten-liter water samples, flocculation by skimmed milk, gravity sedimentation of the flocculated materials, collection of the precipitate and centrifugation, resuspension of the precipitate in 10 ml phosphate buffer. The viral concentrate is used for the extraction of viral nucleic acids and the specific adenoviruses and polyomaviruses of interest are quantified by qPCR. High number of samples may be simultaneously analyzed using this low-cost concentration method.
The procedure has been applied to the analysis of bathing waters, seawater and river water and in this study, we present results analyzing groundwater samples. This high-throughput quantitative method is reliable, straightforward, and cost-effective.

The study describes a cost-effective method for the identification of the source of fecal/urine contamination or contamination by nitrates in water using qPCR for the specific quantification of human/porcine/bovine DNA viruses, adenoviruses and polyomaviruses, proposed as MST tools.

Microbial contamination of the environment represents a significant health risk. Classical bacterial fecal indicators have shown to have significant ...

Isolation and Genome Analysis of Single Virions using 'Single Virus Genomics'

Whole genome amplification and sequencing of single microbial cells enables genomic characterization without the need of cultivation 1-3. Viruses, which are ubiquitous and the most numerous entities on our planet 4 and important in all environments 5, have yet to be revealed via similar approaches. Here we describe an approach for isolating and characterizing the genomes of single virions called 'Single Virus Genomics' (SVG). SVG utilizes flow cytometry to isolate individual viruses and whole genome amplification to obtain high molecular weight genomic DNA (gDNA) that can be used in subsequent sequencing reactions.

Single Virus Genomics (SVG) is a method to isolate and amplify the genomes of single virons. Viral suspensions of a mixed assemblage are sorted using flow cytometry onto a microscope slide with discrete wells containing agarose, thereby capturing the virion and reducing genome shearing during downstream processing. Whole genome amplification is achieved using multiple displacement amplification (MDA) resulting in genomic material that is suitable for sequencing.

Whole genome amplification and sequencing of single microbial cells enables genomic characterization without the need of cultivation 1-3. Viruses, which ...

Development and Testing of Species-specific Quantitative PCR Assays for Environmental DNA Applications

New, non-invasive methods for detecting and monitoring species presence are being developed to aid in fisheries and wildlife conservation management. The use of environmental DNA (eDNA) samples for detecting macrobiota is one such group of methods that is rapidly becoming popular and being implemented in national management programs. Here we focus on the development of species-specific targeted assays for probe-based quantitative PCR (qPCR) applications. Using probe-based qPCR offers greater specificity than is possible with primers alone. Furthermore, the ability to quantify the amount of DNA in a sample can be useful in our understanding of the ecology of eDNA and the interpretation of eDNA detection patterns in the field. Careful consideration is needed in the development and testing of these assays to ensure the sensitivity and specificity of detecting the target species from an environmental sample. In this protocol we will delineate the steps needed to design and test probe-based assays for the detection of a target species; including creation of sequence databases, assay design, assay selection and optimization, testing assay performance, and field validation. Following these steps will help achieve an efficient, sensitive, and specific assay that can be used with confidence. We demonstrate this process with our assay designed for populations of the mucket (Actinonaias ligamentina), a freshwater mussel species found in the Clinch River, USA.

Environmental DNA assays require rigorous design, testing, optimization and validation before the collection of field data can begin. Here, we present a protocol to take users through each step of designing a species-specific, probe-based qPCR assay for the detection and quantification of a target species DNA from environmental samples.

New, non-invasive methods for detecting and monitoring species presence are being developed to aid in fisheries and wildlife conservation management. The ...

Probing RNA Structure with Dimethyl Sulfate Mutational Profiling with Sequencing In Vitro and in Cells

The role of RNA structure in virtually any biological process has become increasingly evident, especially in the past decade. However, classical approaches to solving RNA structure, such as RNA crystallography or cryo-EM, have failed to keep up with the rapidly evolving field and the need for high-throughput solutions. Mutational profiling with sequencing using dimethyl sulfate (DMS) MaPseq is a sequencing-based approach to infer the RNA structure from a base&#39;s reactivity with DMS. DMS methylates the N1 nitrogen in adenosines and the N3 in cytosines at their Watson-Crick face when the base is unpaired. Reverse-transcribing the modified RNA with the thermostable group II intron reverse transcriptase (TGIRT-III) leads to the methylated bases being incorporated as mutations into the cDNA. When sequencing the resulting cDNA and mapping it back to a reference transcript, the relative mutation rates for each base are indicative of the base&#39;s &#34;status&#34; as paired or unpaired. Even though DMS reactivities have a high signal-to-noise ratio both in vitro and in cells, this method is sensitive to bias in the handling procedures. To reduce this bias, this paper provides a protocol for RNA treatment with DMS in cells and with in vitro transcribed RNA.

Probing RNA Structure with Dimethyl Sulfate Mutational Profiling with Sequencing In Vitro and in Cells

The protocol provides instruction for modifying RNA with dimethyl sulfate for mutational profiling experiments. It includes in vitro and in vivo probing with two alternative library preparation methods.

The role of RNA structure in virtually any biological process has become increasingly evident, especially in the past decade. However, classical ...

Biochemistry

Standardized Protocol for Viral Genome Quantification Using Digital Droplet PCR

Quantification of Adeno-Associated Viral Genomes in Purified Vector Samples by Digital Droplet Polymerase Chain Reaction

Adeno-associated virus (AAV) is a non-pathogenic virus used as a delivery vehicle to transfer therapeutic genes into patients. Accurate quantification of AAV genome copy number in vector preparations is essential for bioprocess optimization and dosage calculation in both preclinical and clinical studies of AAV-based gene therapy products. Currently, a consensus protocol for AAV viral genome titration is lacking. Here, we present a digital droplet PCR (dd_PCR) protocol for the quantification of viral genomes in purified vector samples. Samples are treated with DNase I to eliminate unpackaged contaminant DNA. DNase-treated samples are then mixed with an appropriate primer-probe set (designed according to the target AAV genome) and PCR reagents, and then loaded into a droplet generator. The prepared droplets are transferred into a PCR plate, where PCR amplification is performed and analyzed. The viral genome titer is calculated based on the concentration (copies/&#181;L), accounting for sample dilutions. A successful measurement shows a clear separation of the positive and negative droplet clouds, has at least 10,000 accepted droplets, shows a value between 10 copies/&#181;L and 10,000 copies/&#181;L, and has a coefficient of variation (CV) between repeats lower than 20%. Reliable viral genome titration will aid in the development of safe and effective AAV-based gene therapy products.

Author Spotlight: Optimizing Digital Droplet PCR Method for Accurate Adeno-Associated Viral Genome Quantification

Precise quantification of adeno-associated virus (AAV) vector genome copies is critical, but a standardized protocol has yet to be established. This protocol describes a validated method for preparing purified AAV samples and conducting digital droplet polymerase chain reaction (dd_PCR) to reliably quantify the viral genome titer.

Adeno-associated virus (AAV) is a non-pathogenic virus used as a delivery vehicle to transfer therapeutic genes into patients. Accurate quantification of ...

Bioengineering

Purifying the Impure: Sequencing Metagenomes and Metatranscriptomes from Complex Animal-associated Samples

The accessibility of high-throughput sequencing has revolutionized many fields of biology. In order to better understand host-associated viral and microbial communities, a comprehensive workflow for DNA and RNA extraction was developed. The workflow concurrently generates viral and microbial metagenomes, as well as metatranscriptomes, from a single sample for next-generation sequencing. The coupling of these approaches provides an overview of both the taxonomical characteristics and the community encoded functions. The presented methods use Cystic Fibrosis (CF) sputum, a problematic sample type, because it is exceptionally viscous and contains high amount of mucins, free neutrophil DNA, and other unknown contaminants. The protocols described here target these problems and successfully recover viral and microbial DNA with minimal human DNA contamination. To complement the metagenomics studies, a metatranscriptomics protocol was optimized to recover both microbial and host mRNA that contains relatively few ribosomal RNA (rRNA) sequences. An overview of the data characteristics is presented to serve as a reference for assessing the success of the methods. Additional CF sputum samples were also collected to (i) evaluate the consistency of the microbiome profiles across seven consecutive days within a single patient, and (ii) compare the consistency of metagenomic approach to a 16S ribosomal RNA gene-based sequencing. The results showed that daily fluctuation of microbial profiles without antibiotic perturbation was minimal and the taxonomy profiles of the common CF-associated bacteria were highly similar between the 16S rDNA libraries and metagenomes generated from the hypotonic lysis (HL)-derived DNA. However, the differences between 16S rDNA taxonomical profiles generated from total DNA and HL-derived DNA suggest that hypotonic lysis and the washing steps benefit in not only removing the human-derived DNA, but also microbial-derived extracellular DNA that may misrepresent the actual microbial profiles.

Using the cystic fibrosis airway as an example, the manuscript presents a comprehensive workflow comprising a combination of metagenomic and metatranscriptomic approaches to characterize the microbial and viral communities in animal-associated samples.

The accessibility of high-throughput sequencing has revolutionized many fields of biology. In order to better understand host-associated viral and ...

Biology

Quasi-metagenomic Analysis of Salmonella from Food and Environmental Samples

Quasi-metagenomics sequencing refers to the sequencing-based analysis of modified microbiomes of food and environmental samples. In this protocol, microbiome modification is designed to concentrate genomic DNA of a target foodborne pathogen contaminant to facilitate the detection and subtyping of the pathogen in a single workflow. Here, we explain and demonstrate the sample preparation steps for the quasi-metagenomics analysis of Salmonella enterica from representative food and environmental samples including alfalfa sprouts, ground black pepper, ground beef, chicken breast and environmental swabs. Samples are first subjected to the culture enrichment of Salmonella for a shortened and adjustable duration (4&#8211;24 h). Salmonella cells are then selectively captured from the enrichment culture by immunomagnetic separation (IMS). Finally, multiple displacement amplification (MDA) is performed to amplify DNA from IMS-captured cells. The DNA output of this protocol can be sequenced by high throughput sequencing platforms. An optional quantitative PCR analysis can be performed to replace sequencing for Salmonella detection or assess the concentration of Salmonella DNA before sequencing.

Quasi-metagenomic Analysis of Salmonella from Food and Environmental Samples

Here, we present a protocol to prepare DNA samples from food and environmental microbiomes for concerted detection and subtyping of Salmonella through quasimetagenomic sequencing. The combined use of culture enrichment, immunomagnetic separation (IMS), and multiple displacement amplification (MDA) allows effective concentration of Salmonella genomic DNA from food and environmental samples.&#160;

Preparation of DMMTA^V and DMDTA^V Using DMA^V for Environmental Applications: Synthesis, Purification, and Confirmation

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Unraveling the Unseen Players in the Ocean - A Field Guide to Water Chemistry and Marine Microbiology

In vitro tRNA Methylation Assay with the Entamoeba histolytica DNA and tRNA Methyltransferase Dnmt2 (Ehmeth) Enzyme

Biochemical Measurement of Neonatal Hypoxia

Cost-effective Method for Microbial Source Tracking Using Specific Human and Animal Viruses

Isolation and Genome Analysis of Single Virions using 'Single Virus Genomics'

Development and Testing of Species-specific Quantitative PCR Assays for Environmental DNA Applications

Probing RNA Structure with Dimethyl Sulfate Mutational Profiling with Sequencing In Vitro and in Cells

Quantification of Adeno-Associated Viral Genomes in Purified Vector Samples by Digital Droplet Polymerase Chain Reaction

Purifying the Impure: Sequencing Metagenomes and Metatranscriptomes from Complex Animal-associated Samples

Quasi-metagenomic Analysis of Salmonella from Food and Environmental Samples