Name: small-scale colorimetric assays of intracellular lactate and pyruvate in the nematode caenorhabditis elegans
Uploaded: 2018-10-15T14:00:00
Description: Watch this Scientific Journal Video about Small-Scale Colorimetric Assays of Intracellular Lactate and Pyruvate in the Nematode Caenorhabditis elegans at JoVE.com

This work was financially supported by a Special Research Grant from Daito Bunka University to Sumino Yanase.

1. Synchronized Culture of C. elegans
<ol>
	<li>Before seeding, culture the Escherichia coli (E. coli) strain OP50 overnight at 37 &#176;C in 300 mL of Luria-Bertani (LB) broth liquid medium. Store the cultured OP50 at -4 &#176;C.
	<ol>
		<li>To make LB broth liquid medium, use 10 g of tryptone, 5 g of yeast extract, 10 g of NaCl and 1.5 mL of 1 N NaOH, and add to 1 L with deionized water. Autoclave. 
		NOTE: OP50 and C. elegans strains are available from the Caenorhabditis Gene...

<ol>
	<li>Warburg, O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=On+the+origin+of+cancer+cells.">On the origin of cancer cells.</a> Science. 123, 309-314 (1956).</li><li>Matoba, 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=p53+regulates+mitochondrial+respiration.">p53 regulates mitochondrial respiration.</a> Science. 312, 1650-1653 (2006).</li><li>Yanase, S., Suda, H., Yasuda, K., Ishii, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Impaired+p53/CEP-1+is+associated+with+lifespan+extension+through+an+age-related+imbalance+in+the+energy+metabolism+of+C.+elegans.">Impaired p53/CEP-1 is associated with lifespan extension through an age-related imbalance in the energy metabolism of C. elegans.</a> Genes to Cells. 22 (12), 1004-1010 (2017).</li><li>Page, A. P., Johnstone, I. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+cuticle.">The cuticle.</a> WormBook. , (2007).</li><li>Hulme, S. E., Whitesides, G. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chemistry+and+the+worm:+Caenorhabditis+elegans+as+a+platform+for+integrating+chemical+and+biological+research.">Chemistry and the worm: Caenorhabditis elegans as a platform for integrating chemical and biological research.</a> Angewandte Chemie International Edition. 50, 4774-4807 (2011).</li><li>Lewis, J. A., Fleming, J. T., Epstein, H. F., Shakes, D. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Basic+culture+methods.">Basic culture methods.</a> Methods in Cell Biology, Volume 48, Caenorhabditis elegans: Modern Biological Analysis of an Organism. , 3-29 (1995).</li><li>Senoo-Matsuda, N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+defect+in+the+cytochrome+b+large+subunit+in+complex+II+causes+both+superoxide+anion+overproduction+and+abnormal+energy+metabolism+in+Caenorhabditis+elegans.">A defect in the cytochrome b large subunit in complex II causes both superoxide anion overproduction and abnormal energy metabolism in Caenorhabditis elegans.</a> The Journal of Biological Chemistry. 276 (45), 41553-41558 (2001).</li><li>Butler, J. A., Mishur, R. J., Bhaskaran, S., Rea, S. L. <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+signature+for+long+life+in+the+Caenorhabditis+elegans+Mit+mutants.">A metabolic signature for long life in the Caenorhabditis elegans Mit mutants.</a> Aging Cell. 12, 130-138 (2013).</li><li>Marbach, E. P., Weil, M. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rapid+enzymatic+measurement+of+blood+lactate+and+pyruvate:+Use+and+significance+of+metaphosphoric+acid+as+a+common+precipitant.">Rapid enzymatic measurement of blood lactate and pyruvate: Use and significance of metaphosphoric acid as a common precipitant.</a> Clinical Chemistry. 13 (4), 314-325 (1967).</li><li>Mishur, R. 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=Mitochondrial+metabolites+extend+lifespan.">Mitochondrial metabolites extend lifespan.</a> Aging Cell. 15, 336-348 (2016).</li></ol>

When utilizing these colorimetric assay kits, the most critical step in sample extraction to detect cellular lactate and pyruvate accurately in C. elegans is the process of protein precipitation during homogenization (Figure 1). It is not strictly necessary to use a Teflon homogenizer, as other homogenizers (e.g., Dounce and tapered tissue grinders, or bead mills) are also suited to the small-scale extraction of worms. We did not detect cellular lactate and pyruvate in test...

Lactate and pyruvate concentrations are widely regarded as intermediates of energy metabolism, and are related to the states of glycolysis, tricarboxylic acid (TCA) cycle, and electron transport chain in the cells of aerobic organisms. A series of reactions in glycolysis oxidize glucose to pyruvate, which lies at a metabolic crossroads and can be converted to carbohydrates through gluconeogenesis, to fatty acids and energy metabolism through acetyl-CoA, and to the amino acid alanine. The TCA cycle occurs under the presence of sufficient dissolved oxygen and is fundamental for the conversion of glucose to energy. Especially, the alteration of secondary metabolism is an interesting phenomenon in which glycolysis is used predominantly for energy production and aerobic mitochondrial respiration, which involves the TCA cycle and electron transport chain, is downregulated in mammalian cancer cells1,2. We showed recently that the lactate levels and the consequent lactate/pyruvate (L/P) ratio decreased during aging in the model organism Caenorhabditis elegans (C. elegans). Likewise, we found that the mammalian tumor suppressor p53 ortholog CEP-1 in C. elegans has an important role in the age-related alterations of energy metabolism through the activation of its transcriptional targets3.
In biological assays, such as the measurement of lactate and pyruvate concentrations in cells, the sensitivity, accuracy, sample size, and incubation time of colorimetric/fluorimetric assay kits have been improved dramatically. Owing to technological innovations, we are now able to analyze various metabolites and intermediate metabolites without the large-scale culture of C. elegans, which is difficult given its small size. In general, the sensitivity of a colorimetric assay is an order of magnitude smaller than that of a fluorimetric assay; however, the colorimetric approach is more suitable in the setting of common laboratories. Furthermore, an extraction technique containing homogenization and protein precipitation is crucial for the quantitative determination of lactate and pyruvate concentrations in C. elegans cells because this nematode is enclosed in an exoskeleton called the cuticle, unlike mammalian cultured cell lines4,5. Here, we describe a protocol to analyze lactate and pyruvate concentrations using commercial colorimetric assay kits including tips for sample extraction from C. elegans.

<table border="0" cellpadding="0" cellspacing="0" style="width:696px;" width="696">
	<tbody>
		<tr height="62">
			<td height="62" style="height:62px;width:247px;">Lactate Colorimetric/Fluorimetric Assay kit&#160;</td>
			<td style="width:100px;">BioVision</td>
			<td style="width:136px;">#K607-100</td>
			<td style="width:213px;">colorimetric/fluorimetric 
			100 assays; Store at -20oC</td>
		</tr>
		<tr height="38">
			<td height="38" style="height:38px;width:247px;">EnzyChrom Pyruvate 
			Assay Kit</td>
			<td style="width:100px;">BioAssay 
			Systems</td>
			<td style="width:136px;">#EPYR-100</td>
			<td style="width:213px;">colorimetric/ fluorometric 
			100 assays; Store at -20oC</td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:247px;">BCA Protein Assay Kit</td>
			<td style="width:100px;">Thermo Scientific</td>
			<td style="width:136px;">#23225</td>
			<td style="width:213px;">colorimetric assay; store at 
			&#160;room temperature</td>
		</tr>
		<tr height="38">
			<td height="38" style="height:38px;width:247px;">Trichloroacetic Acid</td>
			<td style="width:100px;">Wako Pure Chemical</td>
			<td style="width:136px;">#207-04955</td>
			<td>store at room temperature</td>
		</tr>
		<tr height="38">
			<td height="38" style="height:38px;width:247px;">Teflon homogenizer&#160;</td>
			<td style="width:100px;">Iwaki/Pyrex</td>
			<td style="width:136px;">#358034 (Wheaton)</td>
			<td style="width:213px;">Instead of Iwaki/Pyrex, 
			available by Wheaton</td>
		</tr>
	</tbody>
</table>

small-scale colorimetric assays of intracellular lactate and pyruvate in the nematode caenorhabditis elegans

Lactate and pyruvate are key intermediates of intracellular energy metabolic pathways. Monitoring the lactate/pyruvate ratio in cells helps to determine whether there is an imbalance in age-related energy metabolism between mitochondrial oxidative phosphorylation and aerobic glycolysis. Here, we show the utilization of commercial colorimetric assay kits for lactate and pyruvate in the model organism C. elegans. Recently, the sensitivity and accuracy of the colorimetric/fluorimetric assay kits have been improved greatly by the research and development conducted by reagent manufacturers. The improved reagents have enabled the use of small-scale assays with a 96-well plate in C. elegans. In general, a fluorimetric assay is superior in sensitivity to a colorimetric assay; however, the colorimetric approach is more suitable for the use in common laboratories. Another important issue in these assays for quantitative determination is protein precipitation of homogenized C. elegans samples. In our protein precipitation method, common precipitants (e.g., trichloroacetic acid, perchloric acid and metaphosphoric acid) are used for sample preparation. A protein-free assay sample is prepared by directly adding cold precipitant (final concentration of 5%) during homogenization.

Using the colorimetric assays for the quantitative determination of lactate and pyruvate concentrations, we showed the accuracy of these assays compared with previous reports in C. elegans7,8. Here, the process of protein precipitation during sample extraction was the most crucial step to generate accurate values. For protein precipitation, common precipitants (e.g., TCA, PCA, or metaphosphoric acid) can be used ...

Watch this Scientific Journal Video about Small-Scale Colorimetric Assays of Intracellular Lactate and Pyruvate in the Nematode Caenorhabditis elegans at JoVE.com

Small-Scale Colorimetric Assays of Intracellular Lactate and Pyruvate in the Nematode Caenorhabditis elegans

We describe a modified small-scale extraction and colorimetric assays of lactate and pyruvate in the nematode C. elegans. When utilizing commercial assay kits, the technical development of their sensitivity and accuracy is important. Protein precipitation in extraction is the most critical step for the quantitative determination of intracellular metabolites.

Small-Scale Colorimetric Assays of Intracellular Lactate and Pyruvate in the Nematode Caenorhabditis elegans

Lactate and pyruvate are key intermediates of intracellular energy metabolic pathways. Monitoring the lactate/pyruvate ratio in cells helps to determine ...

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