Name: lipid index determination by liquid fluorescence recovery in the fungal pathogen ustilago maydis
Uploaded: 2018-04-03T15:00:00
Description: Watch this Scientific Journal Video about Lipid Index Determination by Liquid Fluorescence Recovery in the Fungal Pathogen Ustilago Maydis at JoVE.com

This work was supported by grants Instituto Polit&#233;cnico Nacional-Secretaria de Investigaci&#243;n y Posgrado (IPN-SIP-20170864), Programa de Apoyo a Proyectos de Investigaci&#243;n e Innovaci&#243;n Tecnol&#243;gica (PAPIIT IN222117)- Universidad Nacional Aut&#243;noma de M&#233;xico (UNAM), and Consejo Nacional de Ciencia y Tecnolog&#237;a (CONACyT 254904-JPP and 256520-GGS). Funda&#231;&#227;o de Amparo a Pesquisa do Rio de Janeiro (FAPERJ-Cientistas do Nosso Estado: E 26/103.353/2011). We thanks to QFB. Oscar Iv&#225;n Luque&#241;o Bocardo for the schematic overview. We thank Dr. Miguel Tapia Rodr&#237;guez for the valuable help in the confocal microscopy of LDs.&#160;We wish to thank Dr. Bruno Bozaquel Morais for his pioneering work in developing the technique in S. cerevisiae that we adapted for U. maydis.&#160;

1. Preparation of Buffers and Solutions
<ol>
	<li>To prepare 1 L of phosphate buffered saline (PBS, pH 7), dissolve 8 g of NaCl, 0.2 g of KCl, 1.44 g of Na2HPO4, 0.24 g of KH2PO4 in 800 mL of distillated water. Adjust the pH to 7.0 with HCl, and then add water for a final volume of 1 L. PBS can be made as a 10x stock solution and stored at room temperature.</li>
	<li>To prepare 10 mL of fixing solution, add 1 mL of 37% formaldehyde to 9 mL of PBS to reach a final concentratio...

<ol>
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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=The+role+of+lipid+droplets+in+metabolic+disease+in+rodents+and+humans.">The role of lipid droplets in metabolic disease in rodents and humans.</a> Journal of Clinical Investigation. 121 (6), 2102-2110 (2011).</li><li>Aguilar, L. 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=Lipid+droplets+accumulation+and+other+biochemical+changes+induced+in+the+fungal+pathogen+Ustilago+maydis+under+nitrogen-starvation.">Lipid droplets accumulation and other biochemical changes induced in the fungal pathogen Ustilago maydis under nitrogen-starvation.</a> Archives of Microbiology. , (2017).</li><li>Bozaquel-Morais, B. L., Madeira, J. B., Maya-Monteiro, C. M., Masuda, C. A., Montero-Lomeli, 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+new+fluorescence-based+method+identifies+protein+phosphatases+regulating+lipid+droplet+metabolism.">A new fluorescence-based method identifies protein phosphatases regulating lipid droplet metabolism.</a> PLoS One. 5 (10), e13692 (2010).</li><li>Madeira, J. 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=TORC1+Inhibition+Induces+Lipid+Droplet+Replenishment+in+Yeast.">TORC1 Inhibition Induces Lipid Droplet Replenishment in Yeast.</a> Molecular and Cellular Biology. 35 (4), 737-746 (2015).</li><li>Maya-Monteiro, C. 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LFR is a novel method that was applied for the first time to study the lipid metabolism in S. cerevisiae and later it was successfully implemented in U. maydis20,21. Although the LD index does not give an absolute value of the TAGs accumulated in cells, it provides a fast idea of the lipid content of cells, and the interpretation of the data is straightforward when LD index from two or more experimental conditions are compared. BODIPY 493/503 is...

Lipid droplets (LDs) are ubiquitous intracellular fat bodies composed of a core of neutral lipids, mainly TAGs and sterol esters (SE). The core is surrounded by a monolayer of phospholipids that interacts with proteins like perilipin and enzymes involved in the synthesis of neutral lipids, such as the diacylglycerol acyl-transferase, acetyl-CoA carboxylase and acyl-CoA synthase1. Due to its dynamic behavior, the phospholipid monolayer also contains triacylglycerol lipases that hydrolyze TAGs and SE2. Depending on the cell type and organism, stored neutral lipids can be used to generate energy, or synthesize phospholipids and signaling molecules. In yeast and other fungi, the content of LDs changes in response to variations in the nitrogen/carbon ratio in the culture media, indicating that decreased nitrogen availability might be the key to increase neutral lipid production3,4,5. The production of high amounts of TAGs in yeast has a potential use in biotechnology as source of biofuels and in the food industry. Some stored lipids contain high proportions of polyunsaturated fatty acids, like omega 3 and omega 6, with nutritional and dietary importance 6,7,8,9,10,11. LDs of mammalian cells, including human cells, also contain TAGs and cholesterol esters. The phospholipid monolayer interacts with the mammalian homologous of the proteins described in the yeast LDs, and with an additional protein, perilipin, which is absent in S. cerevisiae12. One proposed role for the phospholipid monolayer and its associated proteins is to stabilize the LDs structure and to allow the interaction of LDs with organelles as mitochondria, endoplasmic reticulum, peroxisomes, and vacuoles, mainly for lipid exchange 13,14. Interestingly, in humans, LDs appear to be involved in pathologies like type 2 diabetes, atherosclerosis, steatohepatitis, and coronary heart disease, in which there is an increase in their number 15,16,17. Some types of viruses use LDs as platforms to assemble the virions 2,18,19.
Due to the implications of the LDs in human pathologies and their potential biotechnological use, the exact experimental determination of LDs formation is an important task. This article describes a reliable assay based on the recovery of the fluorescence (LFR) of BODIPY 493/503 (4, 4-difluoro-1, 3, 5, 7, 8-pentamethyl-4-bora-3a, 4a-diaza-s-indacene), to get a relative value of the content of neutral lipids in cells. With this assay, it is possible to follow the dynamics of the accumulation of neutral lipids in fungi like U. maydis and S. cerevisiae, and also in mammalian cells, without the need of lipid extraction 20. The method was applied for the first time in S. cerevisiae to identify the protein phosphatases and kinases involved in the regulation of lipid metabolism. This was possible without lipid extraction or protein purification21,22. LFR also has been used to establish the dynamics of LDs formation in peritoneal macrophages23. The use of BODIPY 493/503 has some advantages over other neutral lipid dyes as Nile Red. BODIPY 493/503 is highly specific for neutral lipids and has a narrow emission spectrum, facilitating the simultaneous detection of signals from dyes like red fluorescent protein or Mito-tracker, when the samples are analyzed by confocal microscopy. Unfortunately, BODIPY 493/503 is sensitive to photobleaching, but this process can be avoided by using an antiquenching reagent during exposure to light24.
To carry out the LFR assay in yeast cells, they are cultured under the desired nutritional conditions, and aliquots are withdrawn at different times. Next, cells are fixed with formaldehyde, which preserves the integrity of LDs for months when cells are stored at 4 &#176;C. Other fixation techniques should be avoided, especially those using methanol or cold acetone, since they lead to the degradation of LDs within the cells24. To measure the LD index, formaldehyde-fixed cells are suspended in water to obtain a defined concentration. Then, they are added to a solution containing the fluorophore BODIPY 493/503 quenched by KI, and when the fluorophore enters the cell and associates with the LDs, there is a recovery of its fluorescence. Concomitant to the fluorescence measurement (485 nm/510 nm), the concentration of cells is quantified by measuring the optical density at 600 nm. Each sample is read four times by adding subsequent 5 &#181;L aliquots of a formaldehyde-fixed cell suspension to the same well. Blanks of fluorescence and absorbance are acquired before the addition of cells. The quality of the fluorescence and the absorbance data are evaluated by determining the linearity of the measurements: if r &#60;0.9, data are discarded. The r value is important because basically the intensity of fluorescence should produce a linear response to increasing cell concentrations. If the cell concentration is too high, the linearity is lost. The LFR assay provides a fast, simple and economic method to select the desired LD phenotype in high-throughput experiments. After selecting the desired conditions, the LD content of individual cells can be studied by confocal microscopy, using the same formaldehyde-fixed cells stained with BODIPY, providing an image of the LDs in the cell. Their TAGs and SE content can now be further analyzed by thin layer chromatography.

<table>
	<tbody>
		<tr>
			<td>Spectrophotometer</td>
			<td>Varioskan Lux multimode microplate reade</td>
			<td>D5879</td>
			<td>Filter 493/503 or monochromator detector</td>
		</tr>
		<tr>
			<td>Plate costar</td>
			<td>Corning Inc.</td>
			<td>3615</td>
			<td>96 well black-wall/clear bottom</td>
		</tr>
		<tr>
			<td>Plate costar&#160;</td>
			<td>Corning Inc</td>
			<td>3598</td>
			<td>96 well cell culture plate costar</td>
		</tr>
		<tr>
			<td>BODIPY 493/503</td>
			<td>Invitrogen/ Thermofisher</td>
			<td>D3922</td>
			<td>4,4-difluoro-1,3,5,7,8-pentamethyl-4-bora-3a,4a-diaza-s-indacene</td>
		</tr>
		<tr>
			<td>Formaldehyde solution</td>
			<td>Sigma Aldrich</td>
			<td>252549</td>
			<td>ACS reagent, 37 wt % in H2O, contains 10-15% methanol to prevent polymerization</td>
		</tr>
		<tr>
			<td>Potassium iodide</td>
			<td>Sigma Aldrich</td>
			<td>60399</td>
			<td>BioUltra, &#8805; 99.5% (AT)</td>
		</tr>
		<tr>
			<td>FB2 Ustilago maydis</td>
			<td>ATCC</td>
			<td>201384</td>
			<td>Basidiomycete-Yeast</td>
		</tr>
		<tr>
			<td>Sodium chloride</td>
			<td>Sigma Aldrich</td>
			<td>746398</td>
			<td>ACS reagent, inorganic salt</td>
		</tr>
		<tr>
			<td>Potassium phosphate monobasic</td>
			<td>Sigma Aldrich</td>
			<td>P0662</td>
			<td>ACS reagent</td>
		</tr>
		<tr>
			<td>Select Yeast Extract</td>
			<td>Sigma Aldrich</td>
			<td>Y100</td>
			<td>Mixture of amini acids, peptides, water- soluble, vitamins and carbohydrates for culture media</td>
		</tr>
		<tr>
			<td>N-Z case plus</td>
			<td>Sigma aldrich</td>
			<td>N4642</td>
			<td>Casein enzymatic hydrolyzate from bovine milk</td>
		</tr>
		<tr>
			<td>Glucose</td>
			<td>Sigma Aldrich</td>
			<td>G-8270</td>
			<td>D (+) glucose</td>
		</tr>
		<tr>
			<td>Skaker flask</td>
			<td>Pirex</td>
			<td>CLS4450250-6EA</td>
			<td>Borosiicate glass</td>
		</tr>
		<tr>
			<td>Shaker</td>
			<td>SEV M&#233;xico</td>
			<td>INO650V-7</td>
			<td>Orbital shaker</td>
		</tr>
		<tr>
			<td>Centrifuge table</td>
			<td>Eppendorf</td>
			<td>5415C</td>
			<td>Centrifuge</td>
		</tr>
		<tr>
			<td>Microtubes</td>
			<td>Sigma Aldrich</td>
			<td>Z606340</td>
			<td>Eppendorf</td>
		</tr>
		<tr>
			<td>Pipet tips</td>
			<td>Axygen scientific</td>
			<td>T-200-Y</td>
			<td>Universal Pipet Tips with Bevelled End, 200 microliter, non sterile</td>
		</tr>
		<tr>
			<td>mLine pipette</td>
			<td>Biohit</td>
			<td>725130</td>
			<td>8 channels, volume range 5-100 uL</td>
		</tr>
	</tbody>
</table>

lipid index determination by liquid fluorescence recovery in the fungal pathogen ustilago maydis

The article shows how to implement the LD index assay, which is a sensitive microplate assay to determine the accumulation of triacylglycerols (TAGs) in lipid droplets (LDs). LD index is obtained without lipid extraction. It allows measuring the LDs content in high-throughput experiments under different conditions such as growth in rich or nitrogen depleted media. Albeit the method was described for the first time to study the lipid droplet metabolism in Saccharomyces cerevisiae, it was successfully applied to the basidiomycete Ustilago maydis. Interestingly, and because LDs are organelles phylogenetically conserved in eukaryotic cells, the method can be applied to a large variety of cells, from yeast to mammalian cells. The LD index is based on the liquid fluorescence recovery assay (LFR) of the BODIPY 493/503 under quenching conditions, by the addition of cells fixed with formaldehyde. Potassium iodine is used as a fluorescence quencher. The ratio between the fluorescence and the optical density slopes is named LD index. Slopes are calculated from the straight lines obtained when BODIPY fluorescence and optical density at 600 nm (OD600) are plotted against sample addition. Optimal data quality is reflected by correlation coefficients equal or above 0.9 (r &#8805; 0.9). Multiple samples can be read simultaneously as it can be implemented in a microplate. Since BODIPY 493/503 is a lipophilic fluorescent dye that partitions into the lipid droplets, it can be used in many types of cells that accumulate LDs.

LFR, with BODIPY 493/503 as the fluorescent probe is a reliable and easy method to study the dynamic accumulation of LDs in U. maydis, regardless the growth conditions. When cells were cultured in YPD-medium, there was an increase in the LD index during the exponential phase, followed by a decline in the stationary phase (Figure 2A). In contrast, in cells grown under nitrogen starvation, there was a steady increase in LD index in both the exponential...

Watch this Scientific Journal Video about Lipid Index Determination by Liquid Fluorescence Recovery in the Fungal Pathogen Ustilago Maydis at JoVE.com

Lipid Index Determination by Liquid Fluorescence Recovery in the Fungal Pathogen Ustilago Maydis

Here, we describe a protocol to obtain the lipid droplet index (LD index) to study the dynamics of triacylglycerols in cells cultured in high-throughput experiments. The LD index assay is an easy and reliable method that uses BODIPY 493/503. This assay does not need dispendious lipid extraction or microscopy analysis.

Lipid Index Determination by Liquid Fluorescence Recovery in the Fungal Pathogen Ustilago Maydis

The article shows how to implement the LD index assay, which is a sensitive microplate assay to determine the accumulation of triacylglycerols (TAGs) in ...

Research

JoVE Journal

Biochemistry

Using Scaffold Liposomes to Reconstitute Lipid-proximal Protein-protein Interactions In Vitro

Using Scaffold Liposomes to Reconstitute Lipid-proximal Protein-protein Interactions In Vitro

Studies of integral membrane proteins in vitro are frequently complicated by the presence of a hydrophobic transmembrane domain. Further complicating ...

Determination of the Glycogen Content in Cyanobacteria

Cyanobacteria accumulate glycogen as a major intracellular carbon and energy storage&#160;during photosynthesis. Recent developments in research have ...

Formation of Covalent DNA Adducts by Enzymatically Activated Carcinogens and Drugs In Vitro and Their Determination by 32P-postlabeling

Formation of Covalent DNA Adducts by Enzymatically Activated Carcinogens and Drugs In Vitro and Their Determination by 32P-postlabeling

Covalent DNA adducts formed by chemicals or drugs with carcinogenic potency are judged as one of the most important factors in the initiation phase of ...

The Determination of Protease Specificity in Mouse Tissue Extracts by MALDI-TOF Mass Spectrometry: Manipulating PH to Cause Specificity Changes

Proteases have several biological functions, including protein activation/inactivation and food digestion. Identifying protease specificity is important ...

Characterization of Glycoproteins with the Immunoglobulin Fold by X-Ray Crystallography and Biophysical Techniques

Glycoproteins on the surface of cells play critical roles in cellular function, including signalling, adhesion and transport. On leukocytes, several of ...

Dissipative Microgravimetry to Study the Binding Dynamics of the Phospholipid Binding Protein Annexin A2 to Solid-supported Lipid Bilayers Using a Quartz Resonator

The dissipative quartz crystal microbalance technique is a simple and label-free approach to measure simultaneously the mass uptake and viscoelastic ...

Expression and Purification of the Human Lipid-sensitive Cation Channel TRPC3 for Structural Determination by Single-particle Cryo-electron Microscopy

Transient receptor potential channels (TRPCs) of the canonical TRP subfamily are nonselective cation channels that play an essential role in calcium ...

Rapid Determination of Antibody-Antigen Affinity by Mass Photometry

Measurements of the specificity and affinity of antigen-antibody interactions are critically important for medical and research applications. In this ...

Semi-Quantitative Analysis of Peptidoglycan by Liquid Chromatography Mass Spectrometry and Bioinformatics

Peptidoglycan is an important component of bacterial cell walls and a common cellular target for antimicrobials. Although aspects of peptidoglycan ...

Crystallization and Structural Determination of an Enzyme:Substrate Complex by Serial Crystallography in a Versatile Microfluidic Chip

The preparation of well diffracting crystals and their handling before their X-ray analysis are two critical steps of biocrystallographic studies. We ...