Name: preparation of drosophila larval samples for gas chromatography-mass spectrometry (gc-ms)-based metabolomics
Uploaded: 2018-06-06T15:00:00
Description: Watch this Scientific Journal Video about Preparation of Drosophila Larval Samples for Gas Chromatography-Mass Spectrometry GC-MS-based Metabolomics at JoVE.com

Thanks to members of the Indiana University Mass Spectroscopy Facility and the University of Utah Metabolomics Core Facility for assistance in optimizing this protocol. J.M.T. is supported by the National Institute of General Medical Sciences of the National Institutes of Health under Award Number R35GM119557.

1. Egg Collection
<ol>
	<li>Collect adult males and virgin females of the desired genotypes. Individually age these animals in a food vial with standard Bloomington media for 3&#8211;5 days.</li>
	<li>Set up the appropriate matings by transferring 50 virgin females and 25 males to a new food vial. 
	NOTE: A minimum of six independent matings should be set up for each genotype. Only one sample will be collected from each mating (i.e., six samples collected from six independent matings).</li>
	<li>Prepare mo...

<ol>
	<li>Owusu-Ansah, E., Perrimon, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Modeling+metabolic+homeostasis+and+nutrient+sensing+in+Drosophila:+implications+for+aging+and+metabolic+diseases.">Modeling metabolic homeostasis and nutrient sensing in Drosophila: implications for aging and metabolic diseases.</a> Disease Models &amp; Mechanisms. 7 (3), 343-350 (2014).</li><li>Sieber, M. H., Spradling, A. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+role+of+metabolic+states+in+development+and+disease.">The role of metabolic states in development and disease.</a> Current Opinion in Genetics &amp; Development. 45, 58-68 (2017).</li><li>Tennessen, J. M., Barry, W. E., Cox, J., Thummel, C. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Methods+for+studying+metabolism+in+Drosophila.">Methods for studying metabolism in Drosophila.</a> Methods. 68 (1), 105-115 (2014).</li><li>Li, 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=Drosophila+larvae+synthesize+the+putative+oncometabolite+L-2-hydroxyglutarate+during+normal+developmental+growth.">Drosophila larvae synthesize the putative oncometabolite L-2-hydroxyglutarate during normal developmental growth.</a> Proceedings of the National Academy of Sciences of the United States of America. 114 (6), 1353-1358 (2017).</li><li>Tennessen, J. M., Baker, K. D., Lam, G., Evans, J., Thummel, C. 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C., Holmes, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Metabonomics':+understanding+the+metabolic+responses+of+living+systems+to+pathophysiological+stimuli+via+multivariate+statistical+analysis+of+biological+NMR+spectroscopic+data.">Metabonomics': understanding the metabolic responses of living systems to pathophysiological stimuli via multivariate statistical analysis of biological NMR spectroscopic data.</a> Xenobiotica. 29 (11), 1181-1189 (1999).</li><li>Fiehn, O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Metabolomics+-+the+link+between+genotypes+and+phenotypes.">Metabolomics - the link between genotypes and phenotypes.</a> Plant Molecular Biology. 48 (1-2), 155-171 (2002).</li><li>Cox, J. E., Thummel, C. S., Tennessen, J. 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Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gas+chromatography/mass+spectrometry+in+metabolic+profiling+of+biological+fluids.">Gas chromatography/mass spectrometry in metabolic profiling of biological fluids.</a> Journal of Chromatography B-Analytical Technologies in the Biomedical and Life Sciences. 871 (2), 202-211 (2008).</li><li>Want, E. J., Nordstrom, A., Morita, H., Siuzdak, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=From+exogenous+to+endogenous:+The+inevitable+imprint+of+mass+spectrometry+in+metabolomics.">From exogenous to endogenous: The inevitable imprint of mass spectrometry in metabolomics.</a> Journal of Proteome Research. 6 (2), 459-468 (2007).</li><li>Garcia, A., Barbas, C., Metz, T. O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Metabolic Profiling: Methods and Protocols Vol. 708 Methods in Molecular Biology. , 191-204 (2011).</li><li>Chan, E. C. Y., Pasikanti, K. K., Nicholson, J. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Global+urinary+metabolic+profiling+procedures+using+gas+chromatography-mass+spectrometry.">Global urinary metabolic profiling procedures using gas chromatography-mass spectrometry.</a> Nature Protocols. 6 (10), 1483-1499 (2011).</li><li>Dunn, W. 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=Procedures+for+large-scale+metabolic+profiling+of+serum+and+plasma+using+gas+chromatography+and+liquid+chromatography+coupled+to+mass+spectrometry.">Procedures for large-scale metabolic profiling of serum and plasma using gas chromatography and liquid chromatography coupled to mass spectrometry.</a> Nature Protocols. 6 (7), 1060-1083 (2011).</li><li>Ashburner, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Drosophila: A Laboratory Manual. , 171-178 (1989).</li><li>Biyasheva, A., Do, T. V., Lu, Y., Vaskova, M., Andres, A. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Glue+secretion+in+the+Drosophila+salivary+gland:+a+model+for+steroid-regulated+exocytosis.">Glue secretion in the Drosophila salivary gland: a model for steroid-regulated exocytosis.</a> Developmental Biology. 231 (1), 234-251 (2001).</li><li>Lommen, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=MetAlign:+Interface-driven,+versatile+metabolomics+tool+for+hyphenated+full-scan+mass+spectrometry+data+preprocessing.">MetAlign: Interface-driven, versatile metabolomics tool for hyphenated full-scan mass spectrometry data preprocessing.</a> Analytical Chemistry. 81 (8), 3079-3086 (2009).</li><li>Xia, J., Wishart, D. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Using+MetaboAnalyst+3.0+for+comprehensive+metabolomics+data+analysis.">Using MetaboAnalyst 3.0 for comprehensive metabolomics data analysis.</a> Current Protocols in Bioinformatics. 55, (2016).</li><li>Xia, J., Sinelnikov, I. V., Han, B., Wishart, D. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=MetaboAnalyst+3.0-making+metabolomics+more+meaningful.">MetaboAnalyst 3.0-making metabolomics more meaningful.</a> Nucleic Acids Research. 43 (W1), W251-W257 (2015).</li><li>Lommen, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Data+(pre-)processing+of+nominal+and+accurate+mass+LC-MS+or+GC-MS+data+using+MetAlign.">Data (pre-)processing of nominal and accurate mass LC-MS or GC-MS data using MetAlign.</a> Methods in Molecular Biology. 860, 229-253 (2012).</li><li>Xia, J., Wishart, D. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Using+MetaboAnalyst+3.0+for+comprehensive+metabolomics+data+analysis.">Using MetaboAnalyst 3.0 for comprehensive metabolomics data analysis.</a> Current Protocols in Bioinformatics. 55, (2016).</li><li>Xia, J., Wishart, D. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Web-based+inference+of+biological+patterns,+functions+and+pathways+from+metabolomic+data+using+MetaboAnalyst.">Web-based inference of biological patterns, functions and pathways from metabolomic data using MetaboAnalyst.</a> Nature Protocols. 6 (6), 743-760 (2011).</li><li>Li, H., Tennessen, 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=Methods+for+studying+the+metabolic+basis+of+Drosophila+development.">Methods for studying the metabolic basis of Drosophila development.</a> Wiley Interdisciplinary Reviews Developmental Biology. 6 (5), (2017).</li></ol>

Metabolomics provides an unparalleled opportunity to survey the metabolic reactions that compose intermediary metabolism. The sensitivity of this technology, however, renders data susceptible to genetic background, developmental cues, and a variety of environmental stresses, including temperature, humidity, population density, and nutrient availability. Therefore, a high quality and reproducible metabolomics analysis requires that samples be collected under highly controlled conditions. While several reviews emphasize th...

The fruit fly Drosophila melanogaster has emerged as an ideal system for studying the molecular mechanism that regulate intermediary metabolism. Not only are most metabolic pathways conserved between Drosophila and humans, but key nutrient sensors and growth regulators, such as insulin, Tor, and myc, are also active in the fly1,2. As a result, Drosophila can be used to explore the metabolic basis of human diseases ranging from diabetes and obesity to neurodegeneration and cancer. In this regard, Drosophila larval development provides the ideal framework in which to study a metabolic program known as aerobic glycolysis, or the Warburg effect. Just as many tumors use aerobic glycolysis to generate biomass from carbohydrates, so to do Drosophila larvae activate aerobic glycolysis to promote developmental growth3,4,5. These similarities between larval and tumor metabolism establish Drosophila as a key model for understanding how aerobic glycolysis is regulated in vivo.
Despite the fact that the fly has emerged as a popular model for studying metabolism, most Drosophila studies rely on methods that are designed to measure individual metabolites3, such as trehalose, triglycerides, or ATP. Since a specific protocol is required to measure each metabolite, assay-based studies are labor-intensive, expensive, and biased towards those compounds that can be measured using commercial kits. A solution to these limitations has emerged from the field of metabolomics, which provides a more efficient and unbiased means of studying Drosophila metabolism. Unlike an assay-based study, a single metabolomic analysis can simultaneously measure hundreds of small molecule metabolites and provide a comprehensive understanding of an organism&#39;s metabolic status6,7. This technique has significantly expanded the scope of Drosophila metabolic studies and represents the future of this emerging field8.
Metabolomic studies are primarily conducted using three technologies: (i) nuclear magnetic resonance (NMR), (ii) liquid chromatography-mass spectrometry (LC-MS), and (iii) gas chromatography-mass spectrometry (GC-MS)9. Each approach offers distinct advantages and disadvantages, and all of these technologies have been used to successfully study Drosophila metabolism. Since the research conducted in our lab is focused on small, polar metabolites, we primarily employ a GC-MS-based method. GC-MS provides the user with a number of advantages, including high reproducibility, peak resolution, sensitivity, and the availability of a standard electron impact (EI) spectral library, which allows for the rapid identification of discovered metabolic features10,11. The preparation of samples for GC-MS, however, is somewhat complex and requires a careful attention to detail. Samples must be collected, washed, weighed, and frozen in a manner that quickly quenches metabolic reactions. Furthermore, the fly carcass is resistant to standard homogenization protocols and requires a bead mill to ensure optimal metabolite extraction. Finally, samples analyzed by GC-MS must undergo chemical derivatization prior to detection12. While previously published methods describe all of these steps3,13,14, a visual protocol that would allow the novice user to reproducibly generate high quality data is still needed. Here we demonstrate how to prepare Drosophila larval samples for GC-MS-based metabolomics analysis. This protocol allows the user to reproducibly measure many of the small polar metabolites that compose central carbon metabolism.

<table border="0" cellpadding="0" cellspacing="0" style="width:827px;" width="826">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:353px;">Unsulfured blackstrap molasses</td>
			<td style="width:141px;">Good Food, INC</td>
			<td style="width:141px;"></td>
			<td style="width:191px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Drosophila Agar Type II</td>
			<td>Genesee Scientific</td>
			<td>66-103</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Pyridine</td>
			<td>EMD Millipore</td>
			<td>PX2012-7</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Methoxyamine hydrocholoride (MOX)</td>
			<td>MP Biomedicals, LLC</td>
			<td>155405</td>
			<td style="width:191px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">MSTFA with 1% trimethylchlorosilane</td>
			<td>Sigma</td>
			<td>69478</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Fleischmann&#8217;s Active dry yeast</td>
			<td>AB Mauri Food Inc</td>
			<td>2192</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">6oz Drosophila stock bottle</td>
			<td>Genesee Scientific</td>
			<td>32-130</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Soft tissue homogenizing mix (2 mL tubes)&#160;</td>
			<td>Omni International</td>
			<td>SKU:19-627</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Vial insert, 250 &#181;L deactivated glass with polymer feet</td>
			<td>Agilent</td>
			<td>5181-8872</td>
			<td></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;">Succinic acid-2,2,3,3-d4</td>
			<td>Sigma</td>
			<td>293075</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">SpeedVac</td>
			<td>Thermo&#160;</td>
			<td>SC210A</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">o-Phosphoric acid</td>
			<td>Fisher Scientific</td>
			<td>A242-1</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Propionic acid</td>
			<td>Sigma</td>
			<td>P5561</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">p-Hydroxy benzoic acid methyl ester</td>
			<td>Genesee Scientific</td>
			<td>20-258</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Bead Ruptor</td>
			<td>Omni International</td>
			<td>SKU:19-040E</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">ThermoMixer F1.5</td>
			<td>Eppendorf</td>
			<td>5384000012</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">MultiTherm Shaker with a 24 X 12 mm block</td>
			<td>Benchmark Scientific</td>
			<td>H5000</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Methanol</td>
			<td>Sigma</td>
			<td>34860</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">1.5 mL centrifuge tube</td>
			<td>Eppendorf</td>
			<td>22364111</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Falcon 35 X 10 mm tissue culture dish</td>
			<td>Corning Incorporated</td>
			<td>353001</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">GC column</td>
			<td>Phenomex</td>
			<td>ZB-5MSi</td>
			<td></td>
		</tr>
	</tbody>
</table>

preparation of drosophila larval samples for gas chromatography-mass spectrometry (gc-ms)-based metabolomics

Recent advances in the field of metabolomics have established the fruit fly Drosophila melanogaster as a powerful genetic model for studying animal metabolism. By combining the vast array of Drosophila genetic tools with the ability to survey large swaths of intermediary metabolism, a metabolomics approach can reveal complex interactions between diet, genotype, life-history events, and environmental cues. In addition, metabolomics studies can discover novel enzymatic mechanisms and uncover previously unknown connections between seemingly disparate metabolic pathways. In order to facilitate more widespread use of this technology among the Drosophila community, here we provide a detailed protocol that describes how to prepare Drosophila larval samples for gas chromatography-mass spectrometry (GC-MS)-based metabolomic analysis. Our protocol includes descriptions of larval sample collection, metabolite extraction, chemical derivatization, and GC-MS analysis. Successful completion of this protocol will allow users to measure the relative abundance of small polar metabolites, including amino acids, sugars, and organic acids involved in glycolysis and the TCA cycles.

Lactate dehydrogenase (dLDH) mutants, which lack dLDH activity4, and genetically-matched controls were collected as mid-L2 larvae and processed according to protocol described above. When compared with controls, mutant larvae exhibit significant changes in lactate, pyruvate, and L-2-hydroxyglutarate4. Spectra were acquired with an Agilent GC6890-5973i MS system. An example of the GC-MS spectra generate with our protocol is shown in ...

Watch this Scientific Journal Video about Preparation of Drosophila Larval Samples for Gas Chromatography-Mass Spectrometry GC-MS-based Metabolomics at JoVE.com

Preparation of Drosophila Larval Samples for Gas Chromatography-Mass Spectrometry GC-MS-based Metabolomics

This protocol describes how to prepare Drosophila larvae for GC-MS-based metabolomic analysis.

Preparation of Drosophila Larval Samples for Gas Chromatography-Mass Spectrometry (GC-MS)-based Metabolomics

Recent advances in the field of metabolomics have established the fruit fly Drosophila melanogaster as a powerful genetic model for studying animal ...

This method can answer key questions in the metabolism field, such as how the oncometabolite L2-hydroxyglutarate is synthesized in healthy cells. The main advantage of this technique is that it allows the user to directly measure over 100 metabolites in a sensitive and reproducible manner. Generally, individuals new to this method will struggle because the protocol requires efficient sample processing and is extremely sensitive to water vapor.To begin the protocol, add one milliliter of ice-cold 0.9%sodium chloride into a 1.5-milliliter tube containing previously prepared larvae. Close the lid, vertically flip the tube to thoroughly wash the larvae, and place the tube on ice for 30 seconds. The larvae will sink to the bottom of the tube, but the yeast will remain in suspension.Once all larvae have formed a loose pellet, remove the sodium chloride solution using a one-milliliter pipette. Centrifuge the samples at 2, 000 g for one minute at four degrees Celsius. Remove all residual solution using a 200-microliter pipette, and immediately freeze the sample in liquid nitrogen.Use an ethanol-proof marker to label the side of a two-milliliter screw-cap bead tube. Next, tare the mass of the labeled bead tube using an analytical balance capable of accurately measuring 0.01 milligrams. Use long forceps to remove the 1.5-milliliter sample tube from the liquid nitrogen dewar.Wearing nitrile gloves, grab the frozen tube, invert it, and sharply pound the tube lid against the benchtop to dislodge the frozen pellet. Immediately pour the pellet into a pre-tared two-milliliter screw-cap bead tube. The sample must be quickly processed to ensure that endogenous metabolic pathways are not reactivated.Quickly measure the combined mass of the larval pellet and bead tube. Immediately place the sample tube into liquid nitrogen. Place the sample tubes in a negative 20 degree Celsius benchtop cooler.Add 0.8 milliliters of pre-chilled 90%methanol containing two micrograms per milliliter of succinic-D4 acid into each tube. Return the samples to the negative 20 degree Celsius benchtop cooler. Set up a negative control by adding 0.8 milliliters of pre-chilled 90%methanol containing two micrograms per milliliter of succinic-D4 acid into an empty bead tube.Then, homogenize the samples for 30 seconds at 6.45 meters per second using a bead mill homogenizer located in a four degree Celsius temperature control room. Return the homogenized samples to the negative 20 degree Celsius benchtop cooler, and transfer the cooler into a negative 20 degree Celsius freezer for at least one hour. After incubating, centrifuge the tubes at 20, 000 g for five minutes at four degrees Celsius to remove the resulting precipitate.Transfer 600 microliters of the supernatant into a new 1.5-milliliter microcentrifuge tube, and do not disturb the precipitate. Open all the sample tubes, and place them in a vacuum centrifuge. Dry the samples at room temperature until all solvent is removed.If the dried samples were stored at negative 80 degrees Celsius, place unopened sample tubes in a vacuum centrifuge and dry them for 30 minutes. Prepare a solution of 40 milligrams per milliliter methoxylamine hydrochloride, or MOX, in anhydrous pyridine. Store the MOX and pyridine in a desiccator.Next, use a heat gun to dry a one-milliliter glass syringe for about five seconds. Insert the needle of the syringe into the bottle of anhydrous pyridine. Remove one milliliter of pyridine, and add it to a microfuge tube containing 40 milligrams of MOX.This portion of the protocol is extremely sensitive to water. All reagents must be stored in a desiccator prior to use. In addition, the user must ensure that the sample has minimal exposure to atmospheric water vapor.Then, flush the bottle of anhydrous pyridine with argon. Seal the bottle, and return it to the desiccator. Dissolve the MOX in pyridine by incubating the tube in a thermal mixer at 35 degrees Celsius for 10 minutes at 600 rpm.Next, add 40 microliters of 40 milligrams per milliliter MOX in anhydrous pyridine solution to the dried sample. Vortex the sample for 10 seconds, and briefly centrifuge it. Then, incubate the sample in a thermal mixer.Centrifuge the sample at 20, 000 g or maximum speed for five minutes to remove the particle matter. Transfer 25 microliters of the supernatant into an autosampler vial with a 250-microliter deactivated glass microvolume insert. Add 40 microliters of MSTFA containing 1%TMCS.Place a cap on the autosampler vial, and seal the vial using a crimper tool. Incubate the sample at 37 degrees Celsius for one hour with shaking at 250 rpm. Finally, add three microliters of previously prepared fatty acid methyl ester standard, or FAMES, solution, to the autosampler vial using a robotic autosampler immediately before injection.Gas chromatography-mass spectrometry of lactate dehydrogenase mutant larvae exhibit significant changes in lactate, pyruvate, and L2-hydroxyglutarate compared with control larvae. The GC-MS spectra generated with the protocol show many visible features and a notable peak for trehalose, which normally represents the largest peak in a larval sample. Principle component analysis, or PCA, clearly shows that the knockout and wild-type groups separate from each other and that there is no outlier in either group.While attempting this procedure, it's important to remember to keep the samples frozen prior to homogenization and to keep all reagents dry throughout the procedure.

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Research

JoVE Journal

Developmental Biology

Preparation of Mitochondrial Enriched Fractions for Metabolic Analysis in Drosophila

Since mitochondria play roles in amino acid metabolism, carbohydrate metabolism and fatty acid oxidation, defects in mitochondrial function often compromise the lives of those who suffer from these complex diseases. Detecting mitochondrial metabolic changes is vital to the understanding of mitochondrial disorders and mitochondrial responses to pharmacological agents. Although mitochondrial metabolism is at the core of metabolic regulation, the detection of subtle changes in mitochondrial metabolism may be hindered by the overrepresentation of other cytosolic metabolites obtained using whole organism or whole tissue extractions. 
Here we describe an isolation method that detected pronounced mitochondrial metabolic changes in Drosophila that were distinct between whole-fly and mitochondrial enriched preparations. To illustrate the sensitivity of this method, we used a set of Drosophila harboring genetically diverse mitochondrial DNAs (mtDNA) and exposed them to the drug rapamycin. Using this method we showed that rapamycin modifies mitochondrial metabolism in a mitochondrial-genotype-dependent manner. However, these changes are much more distinct in metabolomics studies when metabolites were extracted from mitochondrial enriched fractions. In contrast, whole tissue extracts only detected metabolic changes mediated by the drug rapamycin independently of mtDNAs.

Preparation of Mitochondrial Enriched Fractions for Metabolic Analysis in Drosophila

Mitochondria play central roles in the regulation of metabolism and homeostasis. Subtle changes in mitochondrial metabolism that affect organismal physiology could be difficult to detect in whole organism metabolomics studies. Here we describe an isolation method that enhances the detection of subtle metabolic shifts in Drosophila melanogaster.

Since mitochondria play roles in amino acid metabolism, carbohydrate metabolism and fatty acid oxidation, defects in mitochondrial function often ...

Dissection of Larval Zebrafish Gonadal Tissue

Although wild zebrafish possess a ZZ/ZW sex-determination system, domesticated zebrafish have lost the sex chromosome. They utilize a polygenic sex determination system, where several genes distributed throughout the genome collectively determine the sex identities of individual fish. Currently, the genes involved in regulating gonad development and how they work remain elusive. Normally, isolating gonadal tissue is the first step to examine the sex developmental processes. Here, we present a procedure to isolate gonadal tissue from 17 dpf (days post fertilization) and 25 dpf zebrafish larvae. The isolated gonadal tissue may be subsequently examined by morphology and gene expression profiling.

Here, we present a protocol for isolating gonadal tissue of larval zebrafish, which will facilitate investigations of zebrafish sex differentiation and maintenance.

Although wild zebrafish possess a ZZ/ZW sex-determination system, domesticated zebrafish have lost the sex chromosome. They utilize a polygenic sex ...

Medium-scale Preparation of Drosophila Embryo Extracts for Proteomic Experiments

Analysis of protein-protein interactions (PPIs) has become an indispensable approach to study biological processes and mechanisms, such as cell signaling, organism development, and disease. It is often desirable to obtain PPI information using in vivo material, to gain the most natural and unbiased view of the interaction networks. The fruit fly Drosophila melanogaster is an excellent platform to study PPIs in vivo, and lends itself to straightforward approaches to isolating material for biochemical experiments. In particular, fruit fly embryos represent a convenient type of tissue to study PPIs, due to the ease of collecting animals at this developmental stage and the fact that the majority of proteins are expressed in embryogenesis, thus providing a relevant environment to reveal most PPIs. Here we present a protocol for collection of Drosophila embryos at medium scale (0.5-1 g), which is an ideal amount for a wide range of proteomic applications, including analysis of PPIs by affinity purification-mass spectrometry (AP-MS). We describe our designs for 1 L and 5 L cages for embryo collections that can be easily and inexpensively set up in any laboratory. We also provide a general protocol for embryo collection and protein extraction to generate lysates that can be directly used in downstream applications such as AP-MS. Our goal is to provide an accessible means for all researchers to carry out the analyses of PPIs in vivo.

Medium-scale Preparation of Drosophila Embryo Extracts for Proteomic Experiments

The goal of this protocol is to provide a straightforward and inexpensive approach to collecting Drosophila embryos at medium scale (0.5-1 g) and preparing protein extracts that can be used in downstream proteomic applications, such as affinity purification-mass spectrometry (AP-MS).

Analysis of protein-protein interactions (PPIs) has become an indispensable approach to study biological processes and mechanisms, such as cell signaling, ...

Establishment of Larval Zebrafish as an Animal Model to Investigate Trypanosoma cruzi Motility In Vivo

Chagas disease is a parasitic infection caused by Trypanosoma cruzi, whose motility is not only important for localization, but also for cellular binding and invasion. Current animal models for the study of T. cruzi allow limited observation of parasites in vivo, representing a challenge for understanding parasite behavior during the initial stages of infection in humans. This protozoan has a flagellar stage in both vector and mammalian hosts, but there are no studies describing its motility in vivo.The objective of this project was to establish a live vertebrate zebrafish model to evaluate T. cruzi motility in the vascular system. Transparent zebrafish larvae were injected with fluorescently labeled trypomastigotes and observed using light sheet fluorescence microscopy (LSFM), a noninvasive method to visualize live organisms with high optical resolution. The parasites could be visualized for extended periods of time due to this technique&#39;s relatively low risk of photodamage compared to confocal or epifluorescence microscopy. T. cruzi parasites were observed traveling in the circulatory system of live zebrafish in different-sized blood vessels and the yolk. They could also be seen attached to the yolk sac wall and to the atrioventricular valve despite the strong forces associated with heart contractions. LSFM of T. cruzi-inoculated zebrafish larvae is a valuable method that can be used to visualize circulating parasites and evaluate their tropism, migration patterns, and motility in the dynamic environment of the cardiovascular system of a live animal.

Establishment of Larval Zebrafish as an Animal Model to Investigate Trypanosoma cruzi Motility In Vivo

In this protocol, fluorescently labeled T. cruzi&#160;were injected into transparent zebrafish larvae, and parasite motility was observed in vivo using light sheet fluorescence microscopy.

Chagas disease is a parasitic infection caused by Trypanosoma cruzi, whose motility is not only important for localization, but also for cellular binding ...

Thawing, Culturing, and Cryopreserving Drosophila Cell Lines

There are currently over 160 distinct Drosophila cell lines distributed by the Drosophila Genomics Resource Center (DGRC). With genome engineering, the number of novel cell lines is expected to increase. The DGRC aims to familiarize researchers with using Drosophila cell lines as an experimental tool to complement and drive their research agenda. Procedures for working with a variety of Drosophila cell lines with distinct characteristics are provided, including protocols for thawing, culturing, and cryopreserving cell lines. Importantly, this publication demonstrates the best practices required to work with Drosophila cell lines to minimize the risk of contaminations from adventitious microorganisms or from other cell lines. Researchers who become familiar with these procedures will be able to delve into the many applications that use Drosophila cultured cells including biochemistry, cell biology and functional genomics.

Thawing, Culturing, and Cryopreserving Drosophila Cell Lines

Drosophila cell lines are important reagents for both fundamental and biomedical research. This article provides protocols for thawing, subculturing, and the cryopreservation of commonly used Drosophila cell lines to assist researchers in incorporating the use of these reagents in their research.

There are currently over 160 distinct Drosophila cell lines distributed by the Drosophila Genomics Resource Center (DGRC). With genome engineering, the ...

Development of a Larval Zebrafish Infection Model for Clostridioides difficile

Clostridioides difficile infection (CDI) is considered to be one of the most common healthcare-associated gastrointestinal infections in the United States. The innate immune response against C. difficile has been described, but the exact roles of neutrophils and macrophages in CDI are less understood. In the current study, Danio rerio (zebrafish) larvae are used to establish a C. difficile infection model for imaging the behavior and cooperation of these innate immune cells in vivo. To monitor C. difficile, a labeling protocol using a fluorescent dye has been established. A localized infection is achieved by microinjecting labeled C. difficile, which actively grows in the zebrafish intestinal tract and mimics the intestinal epithelial damage in CDI. However, this direct infection protocol is invasive and causes microscopic wounds, which can affect experimental results. Hence, a more noninvasive microgavage protocol is described here. The method involves delivery of C. difficile cells directly into the intestine of zebrafish larvae by intubation through the open mouth. This infection method closely mimics the natural infection route of C. difficile.

Development of a Larval Zebrafish Infection Model for Clostridioides difficile

Presented here is a safe and effective method to infect zebrafish larvae with fluorescently labeled anaerobic C. difficile by microinjection and noninvasive microgavage.

Clostridioides difficile infection (CDI) is considered to be one of the most common healthcare-associated gastrointestinal infections in the United ...

Preparation of Drosophila Larval and Pupal Testes for Analysis of Cell Division in Live, Intact Tissue

Experimental analysis of cells dividing in living, intact tissues and organs is essential to our understanding of how cell division integrates with development, tissue homeostasis, and disease processes. Drosophila spermatocytes undergoing meiosis are ideal for this analysis because (1) whole Drosophila testes containing spermatocytes are relatively easy to prepare for microscopy, (2) the spermatocytes&#8217; large size makes them well suited for high resolution imaging, and (3) powerful Drosophila genetic tools can be integrated with in vivo analysis. Here, we present a readily accessible protocol for the preparation of whole testes from Drosophila third instar larvae and early pupae. We describe how to identify meiotic spermatocytes in prepared whole testes and how to image them live by time-lapse microscopy. Protocols for fixation and immunostaining whole testes are also provided. The use of larval testes has several advantages over available protocols that use adult testes for spermatocyte analysis. Most importantly, larval testes are smaller and less crowded with cells than adult testes, and this greatly facilitates high resolution imaging of spermatocytes. To demonstrate these advantages and the applications of the protocols, we present results showing the redistribution of the endoplasmic reticulum with respect to spindle microtubules during cell division in a single spermatocyte imaged by time-lapse confocal microscopy. The protocols can be combined with expression of any number of fluorescently tagged proteins or organelle markers, as well as gene mutations and other genetic tools, making this approach especially powerful for analysis of cell division mechanisms in the physiological context of whole tissues and organs.

Preparation of Drosophila Larval and Pupal Testes for Analysis of Cell Division in Live, Intact Tissue

The goal of this protocol is to analyze cell division in intact tissue by live and fixed cell microscopy using Drosophila meiotic spermatocytes. The protocol demonstrates how to isolate whole, intact testes from Drosophila larvae and early pupae, and how to process and mount them for microscopy.

Experimental analysis of cells dividing in living, intact tissues and organs is essential to our understanding of how cell division integrates with ...

Dissection, Immunohistochemistry and Mounting of Larval and Adult Drosophila Brains for Optic Lobe Visualization

The Drosophila optic lobe, comprised of four neuropils: the lamina, medulla, lobula and lobula plate, is an excellent model system for exploring the developmental mechanisms that generate neural diversity and drive circuit assembly. Given its complex three-dimensional organization, analysis of the optic lobe requires that one understand how its adult neuropils and larval progenitors are positioned relative to each other and the central brain. Here, we describe a protocol for the dissection, immunostaining and mounting of larval and adult brains for optic lobe imaging. Special emphasis is placed on the relationship between mounting orientation and the spatial organization of the optic lobe. We describe three mounting strategies in the larva (anterior, posterior and lateral) and three in the adult (anterior, posterior and horizontal), each of which provide an ideal imaging angle for a distinct optic lobe structure.

Dissection, Immunohistochemistry and Mounting of Larval and Adult Drosophila Brains for Optic Lobe Visualization

This protocol describes three steps to prepare larval and adult Drosophila optic lobes for imaging: 1) brain dissections, 2) immunohistochemistry and 3) mounting. Emphasis is placed on step 3, as distinct mounting orientations are required to visualize specific optic lobe structures.&#160;

The Drosophila optic lobe, comprised of four neuropils: the lamina, medulla, lobula and lobula plate, is an excellent model system for exploring the ...

Drosophila Embryo Preparation and Microinjection for Live Cell Microscopy Performed using an Automated High Content Analyzer

Modern approaches in quantitative live cell imaging have become an essential tool for exploring cell biology, by enabling the use of statistics and computational modeling to classify and compare biological processes. Although cell culture model systems are great for high content imaging, high throughput studies of cell morphology suggest that ex vivo cultures are limited in recapitulating the morphological complexity found in cells within living organisms. As such, there is a need for a scalable high throughput model system to image living cells within an intact organism. Described here is a protocol for using a high content image analyzer to simultaneously acquire multiple time-lapse videos of embryonic Drosophila melanogaster development during the syncytial blastoderm stage. The syncytial blastoderm has traditionally served as a great in vivo model for imaging biological events; however, obtaining a significant number of experimental replicates for quantitative and high-throughput approaches has been labor intensive and limited by the imaging of a single embryo per experimental repeat. Presented here is a method to adapt imaging and microinjection approaches to suit a high content imaging system, or any inverted microscope capable of automated multipoint acquisition. This approach enables the simultaneous acquisition of 6-12 embryos, depending on desired acquisition factors, within a single imaging session.

Presented here is a protocol to microinject and simultaneously image multiple Drosophila embryos during embryonic development using a plate-based, high content imager.

Modern approaches in quantitative live cell imaging have become an essential tool for exploring cell biology, by enabling the use of statistics and ...

Imaging Live Brain Explants from Drosophila melanogaster Third Instar Larvae

Live-Cell Imaging of Drosophila melanogaster Third Instar Larval Brains

Drosophila neural stem cells (neuroblasts, NBs hereafter) undergo asymmetric divisions, regenerating the self-renewing neuroblast, while also forming a differentiating ganglion mother cell (GMC), which will undergo one additional division to give rise to two neurons or glia. Studies in NBs have uncovered the molecular mechanisms underlying cell polarity, spindle orientation, neural stem cell self-renewal, and differentiation. These asymmetric cell divisions are readily observable via live-cell imaging, making larval NBs ideally suited for investigating the spatiotemporal dynamics of asymmetric cell division in living tissue. When properly dissected and imaged in nutrient-supplemented medium, NBs in explant brains robustly divide for 12-20 h. Previously described methods are technically difficult and may be challenging to those new to the field. Here, a protocol is described for the preparation, dissection, mounting, and imaging of live third-instar larval brain explants using fat body supplements. Potential problems are also discussed, and examples are provided for how this technique can be used.

Author Spotlight: Investigating Asymmetric Cell Division Dynamics: A Protocol for Live-Imaging of Drosophila Larval Brain Explants 

Here, we discuss a workflow to prepare, dissect, mount, and image live explant brains from Drosophila melanogaster third instar larvae to observe the cellular and subcellular dynamics under physiological conditions.

Drosophila neural stem cells (neuroblasts, NBs hereafter) undergo asymmetric divisions, regenerating the self-renewing neuroblast, while also forming a ...