This work was supported in part by the National Institutes of Health (K01DK114390), a Research Scholar Grant from the American Cancer Society (RSG-18-050-01-NEC), a Research Pilot Project Grant from University of New Mexico Environmental Health Signature Program and Superfund (P42 ES025589), a Shared Resources Pilot Project Award and a Research Program Support Pilot Project Award from UNM comprehensive cancer center (P30CA118100), and a new investigator award from the Dedicated Health Research Funds at the University of New Mexico School of Medicine.

1. Cell seeding
<ol>
	<li>Seed 2 x 105 HCT116 colorectal cancer cells per well in a 24-well plate and maintain the cells in Dulbecco&#39;s modified Eagle medium (DMEM) overnight at 37 &#176;C.</li>
	<li>Replace the culture medium with or without 100 &#181;M ferrous sulfate (FS) or 10 &#181;M doxorubicin (DOX) containing medium and incubate for 24 h.</li>
</ol>
2. Preparation of the DCFH-DA solution
<ol>
	<li>Dissolve 4.85 mg of DCFH-DA in 1 mL of dimethyl sulfoxide (DMSO) to make a 10 mM stock solution.</li>
	<li>Dilute the stock solution with pre-warmed DMEM into 10 &#181;M working solution right before adding it to the wells.</li>
	<li>Vortex the working solution for 10 s.</li>
</ol>
3. DCFH-DA staining
<ol>
	<li>Remove the drug containing medium and wash once with DMEM.</li>
	<li>Add 500 &#181;L of the DCFH-DA working solution into each well and incubate at 37 &#176;C for 30 min.</li>
	<li>Remove the DCFH-DA working solution. Wash once with DMEM and 2x with 1x phosphate-buffered saline (PBS).</li>
	<li>Add 500 &#181;L of 1x PBS to each well.</li>
</ol>
4. Imaging acquisition and intensity measurement
<ol>
	<li>Take representative fluorescent images for each well using the green fluorescent protein (GFP) channel on a fluorescence microscope.</li>
	<li>After taking images, remove PBS and add 200 &#181;L of radioimmunoprecipitation assay (RIPA) buffer to each well.</li>
	<li>Incubate on ice for 5 min, then collect cell lysate into 1.5 mL tubes.</li>
	<li>Centrifuge at 21,130 x g for 10 min at 4 &#176;C.</li>
	<li>Transfer 100 &#181;L of the supernatant to a black 96 well plate and measure the fluorescence intensity using a fluorescence a microplate reader at an excitation wavelength of 485 nm and an emission wavelength of 530 nm.</li>
	<li>Transfer 1 &#181;L of the supernatant to a clear 96 well plate containing 100 &#181;L of 1x protein assay solution to measure the protein concentration using the Bradford assay9.</li>
	<li>Normalize fluorescence intensities with protein concentrations.</li>
</ol>

<ol>
	<li>Birben, E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Oxidative+stress+and+antioxidant+defense.">Oxidative stress and antioxidant defense.</a> World Allergy Organization Journal. 5 (1), 9-19 (2012).</li><li>Kim, G. 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=The+Role+of+Oxidative+Stress+in+Neurodegenerative+Diseases.">The Role of Oxidative Stress in Neurodegenerative Diseases.</a> Experimental Neurobiology. 24 (4), 325-340 (2015).</li><li>Sullivan, L. B., Chandel, N. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mitochondrial+reactive+oxygen+species+and+cancer.">Mitochondrial reactive oxygen species and cancer.</a> Cancer &amp; Metabolism. 2, 17 (2014).</li><li>Formentini, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mitochondrial+ROS+Production+Protects+the+Intestine+from+Inflammation+through+Functional+M2+Macrophage+Polarization.">Mitochondrial ROS Production Protects the Intestine from Inflammation through Functional M2 Macrophage Polarization.</a> Cell Reports. 19 (6), 1202-1213 (2017).</li><li>Rakotoarisoa, 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=Curcumin-+and+Fish+Oil-Loaded+Spongosome+and+Cubosome+Nanoparticles+with+Neuroprotective+Potential+against+H2O2-Induced+Oxidative+Stress+in+Differentiated+Human+SH-SY5Y+Cells.">Curcumin- and Fish Oil-Loaded Spongosome and Cubosome Nanoparticles with Neuroprotective Potential against H2O2-Induced Oxidative Stress in Differentiated Human SH-SY5Y Cells.</a> ACS Omega. 4 (2), 3061-3073 (2019).</li><li>Mateen, 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=Increased+Reactive+Oxygen+Species+Formation+and+Oxidative+Stress+in+Rheumatoid+Arthritis.">Increased Reactive Oxygen Species Formation and Oxidative Stress in Rheumatoid Arthritis.</a> PLoS One. 11 (4), (2016).</li><li>Kim, 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=The+interaction+of+Hemin+and+Sestrin2+modulates+oxidative+stress+and+colon+tumor+growth.">The interaction of Hemin and Sestrin2 modulates oxidative stress and colon tumor growth.</a> Toxicology and Applied Pharmacology. 374, 77-85 (2019).</li><li>Wang, S. 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=Sotetsuflavone+inhibits+proliferation+and+induces+apoptosis+of+A549+cells+through+ROS-mediated+mitochondrial-dependent+pathway.">Sotetsuflavone inhibits proliferation and induces apoptosis of A549 cells through ROS-mediated mitochondrial-dependent pathway.</a> BMC Complementary and Alternative Medicine. 18, 235 (2018).</li><li>Kruger, N. J., Walker, 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=The+Bradford+Method+For+Protein+Quantitation.">The Bradford Method For Protein Quantitation.</a> The Protein Protocols Handbook. , 17-24 (2009).</li><li>Tetz, L. 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Z., 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=Quantitative+detection+of+hydroxyl+radical+generated+in+quartz+powder/phosphate+buffer+solution+system+by+fluorescence+spectrophotometry.">Quantitative detection of hydroxyl radical generated in quartz powder/phosphate buffer solution system by fluorescence spectrophotometry.</a> Guang Pu Xue Yu Guang Pu Fen Xi. 34 (7), 1886-1889 (2014).</li></ol>

The authors have nothing to disclose.

The experimental protocol described here is easily reproducible to measure cellular total ROS. The critical steps include making DCFH-DA solution fresh and avoiding light exposure, minimizing cell status disturbance and extensive PBS washing right before taking images. For the preparation of DCFH-DA working solution, the stock solution should be added into pre-warmed DMEM right before adding into the 24 well plate. The reason is that old solutions that generate high background fluorescence or light exposure will lead to ...

Three major reactive oxygen species (ROS) produced by cellular metabolism that are of physiological meaning are superoxide anion, hydroxyl radical, and hydrogen peroxide1. At low concentrations, they participate in physiological cell processes, but at high concentrations they have adverse effects on cell signaling pathways1. Our body has developed antioxidant systems, which are effective against excessive ROS. However, oxidative stress can occur when ROS overwhelm the detoxifying ability of our body, which contributes to many pathological conditions, including inflammation, cancer, and neurodegenerative disease2,3,4. The purpose of this method is to determine total cellular ROS in adherent cells using 2&#39;,7&#39;-dichlorodihydrofluorescein diacetate (DCFH-DA) staining. The rationale is that oxidation of DCFH-DA to 2&#8217;-7&#8217;dichlorofluorescein (DCF) has been used extensively for total ROS detection including hydroxyl radicals (&#8226;OH) and nitrogen dioxide (&#8226;NO2). Mechanistically, DCFH-DA is taken up by cells where cellular esterase cleaves off the acetyl groups, resulting in DCFH. Oxidation of DCFH by ROS converts the molecule to DCF, which emits green fluorescence at an excitation wavelength of 485 nm and an emission wavelength of 530 nm. Compared with detection of fluorescence with flow cytometry and other alternative methods5, advantages of this method using a fluorescence microscope and a plate reader are that it produces clearly visible fluorescent images, and is easy to perform, efficient and cost-effective. This method has been widely used to detect cellular ROS for studying various conditions6,7,8. This protocol is used for detecting total ROS in adherent cells. Using this method to detect ROS in suspension cells may need some modifications.

<table border="0" cellpadding="0" cellspacing="0" style="width:900px;" width="899">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:277px;">2&#39;,7&#39;-Dichlorofluorescein diacetate</td>
			<td style="width:229px;">Cayman Chemical, Ann Arbor, MI</td>
			<td style="width:93px;">20656</td>
			<td style="width:300px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">Doxorubicin hydrochloride</td>
			<td style="width:229px;">TCI America, Portland, OR</td>
			<td style="width:93px;">D4193-25MG</td>
			<td style="width:300px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:277px;">Dulbecco&#39;s Modified Eagle Medium</td>
			<td>Corning, Corning, NY</td>
			<td>45000-304</td>
			<td style="width:300px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:277px;">Ferrous Sulfate Heptahydrate</td>
			<td style="width:229px;">VWR, Radnor, PA</td>
			<td style="width:93px;">97061-542</td>
			<td style="width:300px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">Invitrogen EVOS FL Auto Imaging System</td>
			<td style="width:229px;">Thermo Fisher Scientific Waltham, MA</td>
			<td>AMAFD1000</td>
			<td>or any other fluorescence microscope</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Protein assay Bradford solution</td>
			<td>Bio-Rad, Hercules, CA</td>
			<td style="width:93px;">5000001</td>
			<td style="width:300px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">SpectraMax M2 Microplate Reader</td>
			<td>Molecular Devices, Radnor, PA</td>
			<td>89429-532</td>
			<td>or any other fluorescence microplate reader</td>
		</tr>
	</tbody>
</table>

detection of total reactive oxygen species in adherent cells by 2',7'-dichlorodihydrofluorescein diacetate staining

Oxidative stress is an important event under both physiological and pathological conditions. In this study, we demonstrate how to quantify oxidative stress by measuring total reactive oxygen species (ROS) using 2&#39;,7&#39;-dichlorodihydrofluorescein diacetate (DCFH-DA) staining in colorectal cancer cell lines as an example. This protocol describes detailed steps including preparation of DCFH-DA solution, incubation of cells with DCFH-DA solution, and measurement of normalized intensity. DCFH-DA staining is a simple and cost-effective way to detect ROS in cells. It can be used to measure ROS generation after chemical treatment or genetic modifications. Therefore, it is useful for determining cellular oxidative stress upon environment stress, providing clues to mechanistic studies.

HCT116 colorectal cancer cells were treated with 100 &#181;M FS or 10 &#181;M DOX to induce oxidative stress7. As shown in Figure 1, green fluorescence was dramatically increased by both FS and DOX as expected. To quantify the relative intensity change, the cells were lysed after taking images and normalized with protein concentrations. The quantified fluorescence intensity was significantly increased by FS or DOX in HCT116 cells.
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Watch this Scientific Journal Video about Detection of Total Reactive Oxygen Species in Adherent Cells by 2',7'-Dichlorodihydrofluorescein Diacetate Staining at JoVE.com

Detection of Total Reactive Oxygen Species in Adherent Cells by 2',7'-Dichlorodihydrofluorescein Diacetate Staining

Here, we present a protocol to detect total cellular reactive oxygen species (ROS) using 2&#39;,7&#39;-dichlorodihydrofluorescein diacetate (DCFH-DA). This method can visualize cellular ROS localization in adherent cells with a fluorescence microscope and quantify ROS intensity with a fluorescence plate reader. This protocol is simple, efficient and cost-effective.

Oxidative stress is an important event under both physiological and pathological conditions. In this study, we demonstrate how to quantify oxidative ...

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Biochemistry

29.6K Views.  University of New Mexico. Here, we present a protocol to detect total cellular reactive oxygen species (ROS) using 2',7'-dichlorodihydrofluorescein diacetate (DCFH-DA). This method can visualize cellular ROS localization in adherent cells with a fluorescence microscope and quantify ROS intensity with a fluorescence plate reader. This protocol is simple, efficient and cost-effective.

Video: Detection of Total Reactive Oxygen Species in Adherent Cells by 2',7'-Dichlorodihydrofluorescein Diacetate Staining

DNA Staining Method Based on Formazan Precipitation Induced by Blue Light Exposure

DNA staining methods are very important for biomedical research. We designed a simple method that allows DNA visualization to the naked eye by the formation of a colored precipitate. It works by soaking the acrylamide or agarose DNA gel in a solution of 1x (equivalent to 2.0 &#181;M) SYBR Green I (SG I) and 0.20 mM nitro blue tetrazolium that produces a purple precipitate of formazan when exposed to sunlight or specifically blue light. Also, DNA recovery tests were performed using an ampicillin resistant plasmid in an agarose gel stained with our method. A larger number of colonies was obtained with our method than with traditional staining using SG I with ultraviolet illumination. The described method is fast, specific, and non-toxic for DNA detection, allowing visualization of biomolecules to the "naked eye" without a transilluminator, and is inexpensive and appropriate for field use. For these reasons, our new DNA staining method has potential benefits to both research and industry.

This method allows selective staining and quantification of DNA in gels by soaking the gel in a SYBR Green I/Nitro Blue Tetrazolium solution and then exposing it to sunlight or a blue light source. This produces a visible precipitate and requires almost no equipment, making it ideal for field use.

DNA staining methods are very important for biomedical research. We designed a simple method that allows DNA visualization to the naked eye by the ...

Quantitative and Qualitative Method for Sphingomyelin by LC-MS Using Two Stable Isotopically Labeled Sphingomyelin Species

We present a method of analyzing sphingomyelin (SM) qualitatively and quantitatively by liquid chromatography-electrospray Ionization-tandem mass spectrometry (LC-ESI-MS/MS). SM is a common sphingolipid composed of a phosphorylcholine and a ceramide as the hydrophilic and hydrophobic component, respectively. A number of SM species are present in mammalian cells due to a variety in the sphingoid long chain base (LCB) and an N-acyl moiety in the ceramide. In this report, we show a method of estimating the number of carbon and double bonds in a LCB and an N-acyl moiety based on their corresponding product ions in MS/MS/MS (MS3) experiments. In addition, we present a quantitative analysis method for SM using two stable isotopically labeled SM species, which facilitates determining the range used in SM quantitation. The present method will be useful in characterizing a variety of SM species in biological samples and industrial products such as cosmetics.

Here, we present a protocol to quantify and qualify each sphingomyelin species using multiple reaction monitoring and MS/MS/MS mode, respectively.

We present a method of analyzing sphingomyelin (SM) qualitatively and quantitatively by liquid chromatography-electrospray Ionization-tandem mass ...

Measurement of Mitochondrial Oxygen Consumption in Permeabilized Fibers of Drosophila Using Minimal Amounts of Tissue

The fruit fly, Drosophila melanogaster, represents an emerging model for the study of metabolism. Indeed, drosophila have structures homologous to human organs, possess highly conserved metabolic pathways and have a relatively short lifespan that allows the study of different fundamental mechanisms in a short period of time. It is, however, surprising that one of the mechanisms essential for cellular metabolism, the mitochondrial respiration, has not been thoroughly investigated in this model. It is likely because the measure of the mitochondrial respiration in Drosophila usually requires a very large number of individuals and the results obtained are not highly reproducible. Here, a method allowing the precise measurement of mitochondrial oxygen consumption using minimal amounts of tissue from Drosophila is described. In this method, the thoraxes are dissected and permeabilized both mechanically with sharp forceps and chemically with saponin, allowing different compounds to cross the cell membrane and modulate the mitochondrial respiration. After permeabilization, a protocol is performed to evaluate the capacity of the different complexes of the electron transport system (ETS) to oxidize different substrates, as well as their response to an uncoupler and to several inhibitors. This method presents many advantages compared to methods using mitochondrial isolations, as it is more physiologically relevant because the mitochondria are still interacting with the other cellular components and the mitochondrial morphology is conserved. Moreover, sample preparations are faster, and the results obtained are highly reproducible. By combining the advantages of Drosophila as a model for the study of metabolism with the evaluation of mitochondrial respiration, important new insights can be unveiled, especially when the flies are experiencing different environmental or pathophysiological conditions.

In this paper, a method to measure oxygen consumption using high-resolution respirometry in permeabilized thoraxes of Drosophila is described. This technique requires a minimal amount of tissue compared to the classic mitochondrial isolation technique and the results obtained are more physiologically relevant.

The fruit fly, Drosophila melanogaster, represents an emerging model for the study of metabolism. Indeed, drosophila have structures homologous to human ...

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 properties of the absorbed/immobilized mass on sensor surfaces, allowing the measurements of the interaction of proteins with solid-supported surfaces, such as lipid bilayers, in real-time and with a high sensitivity. Annexins are a highly conserved group of phospholipid-binding proteins that interact reversibly with the negatively charged headgroups via the coordination of calcium ions. Here, we describe a protocol that was employed to quantitatively analyze the binding of annexin A2 (AnxA2) to planar lipid bilayers prepared on the surface of a quartz sensor. This protocol is optimized to obtain robust and reproducible data and includes a detailed step-by-step description. The method can be applied to other membrane-binding proteins and bilayer compositions.

Here, we present an experimental protocol that can be employed to determine the binding affinities and mode of interaction of label-free phospholipid-binding protein annexin A2 with immobilized solid-supported bilayers (SLB) by simultaneously measuring the mass uptake and the viscoelastic properties of the protein annexin A2.

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

Measuring and Interpreting Oxygen Consumption Rates in Whole Fly Head Segments

Regulated metabolic activity is essential for the normal functioning of living cells. Indeed, altered metabolic activity is causally linked with the progression of cancer, diabetes, neurodegeneration, and aging to name a few. For instance, changes in mitochondrial activity, the cell&#39;s metabolic powerhouse, have been characterized in many such diseases. Generally, the oxygen consumption rates of mitochondria were considered a reliable readout of mitochondrial activity and measurements in some of these studies were based on isolated mitochondria or cells. However, such conditions may not represent the complexity of a whole tissue. Recently, we have developed a novel method that enables the dynamic measurement of oxygen consumption rates from whole isolated fly heads. By utilizing this method, we have recorded lower oxygen consumption rates of the whole head segment in young versus aged flies. Secondly, we have discovered that lysine deacetylase inhibitors rapidly alter the oxygen consumption in the whole head. Our novel technique may therefore aid in uncovering new properties of various drugs, which may impact metabolic rates. Furthermore, our method may give a better understanding of metabolic behavior in an experimental setup that more closely resembles physiological states.

Measuring alterations in metabolic rates is central to understanding the progression of various diseases and aging. Here, we present a novel technique to measure whole head oxygen consumption that more closely resembles the physiological state and may aid in revealing novel drugs that modify mitochondrial activity.

Regulated metabolic activity is essential for the normal functioning of living cells. Indeed, altered metabolic activity is causally linked with the ...

Fluorescent Silver Staining of Proteins in Polyacrylamide Gels

Silver staining is a colorimetric technique widely used to visualize protein bands in polyacrylamide gels following sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The classic silver stains have certain drawbacks, such as high background staining, poor protein recovery, low reproducibility, a narrow linear dynamic range for quantification, and limited compatibility with mass spectrometry (MS). Now, with the use of a fluorogenic Ag+ probe, TPE-4TA, we developed a fluorescent silver staining method for the total protein visualization in polyacrylamide gels. This new stain avoids the troublesome silver reduction step in traditional silver stains. Moreover, the fluorescent silver stain demonstrates good reproducibility, sensitivity, and linear quantification in protein detection, making it a useful and practical protein gel stain.

Here, we describe a detailed protocol outlining a new fluorescent staining technique for total protein detection in polyacrylamide gels. The protocol utilizes a silver ion-specific fluorescence turn-on probe, which detects Ag+-protein complexes, and eliminates certain limitations of traditional chromogenic silver stains.

Silver staining is a colorimetric technique widely used to visualize protein bands in polyacrylamide gels following sodium dodecyl sulfate-polyacrylamide ...

Using High Content Imaging to Quantify Target Engagement in Adherent Cells

Quantitating the interaction of small molecules with their intended protein target is critical for drug development, target validation and chemical probe validation. Methods that measure this phenomenon without modification of the protein target or small molecule are particularly valuable though technically challenging. The cellular thermal shift assay (CETSA) is one technique to monitor target engagement in living cells. Here, we describe an adaptation of the original CETSA protocol, which allows for high throughput measurements while retaining subcellular localization at the single cell level. We believe this protocol offers important advances to the application of CETSA for in-depth characterization of compound-target interaction, especially in heterogeneous populations of cells.

Measurements of drug target engagement are central to effective drug development and chemical probe validation. Here, we detail a protocol for measuring drug-target engagement using high content imaging in a microplate-compatible adaption of the cellular thermal shift assay (CETSA).

Quantitating the interaction of small molecules with their intended protein target is critical for drug development, target validation and chemical probe ...

Analysis of Protein Folding, Transport, and Degradation in Living Cells by Radioactive Pulse Chase

Radioactive pulse-chase labeling is a powerful tool for studying the conformational maturation, the transport to their functional cellular location, and the degradation of target proteins in live cells. By using short (pulse) radiolabeling times (&lt;30 min) and tightly controlled chase times, it is possible to label only a small fraction of the total protein pool and follow its folding. When combined with nonreducing/reducing SDS-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoprecipitation with (conformation-specific) antibodies, folding processes can be examined in great detail. This system has been used to analyze the folding of proteins with a huge variation in properties such as soluble proteins, single and multi-pass transmembrane proteins, heavily N- and O-glycosylated proteins, and proteins with and without extensive disulfide bonding. Pulse-chase methods are the basis of kinetic studies into a range of additional features, including co- and posttranslational modifications, oligomerization, and polymerization, essentially allowing the analysis of a protein from birth to death. Pulse-chase studies on protein folding are complementary with other biochemical and biophysical methods for studying proteins in vitro by providing increased temporal resolution and physiological information. The methods as described within this paper are adapted easily to study the folding of almost any protein that can be expressed in mammalian or insect-cell systems.

Here we describe a protocol for a general pulse-chase method that allows the kinetic analysis of folding, transport, and degradation of proteins to be followed in live cells.

Radioactive pulse-chase labeling is a powerful tool for studying the conformational maturation, the transport to their functional cellular location, and ...

Detection of Protein Ubiquitination Sites by Peptide Enrichment and Mass Spectrometry

The posttranslational modification of proteins by the small protein ubiquitin is involved in many cellular events. After tryptic digestion of ubiquitinated proteins, peptides with a diglycine remnant conjugated to the epsilon amino group of lysine (&#39;K-&#949;-diglycine&#39; or simply &#39;diGly&#39;) can be used to track back the original modification site. Efficient immunopurification of diGly peptides combined with sensitive detection by mass spectrometry has resulted in a huge increase in the number of ubiquitination sites identified up to date. We have made several improvements to this workflow, including offline high pH reverse-phase fractionation of peptides prior to the enrichment procedure, and the inclusion of more advanced peptide fragmentation settings in the ion routing multipole. Also, more efficient cleanup of the sample using a filter-based plug in order to retain the antibody beads results in a greater specificity for diGly peptides. These improvements result in the routine detection of more than 23,000 diGly peptides from human cervical cancer cells (HeLa) cell lysates upon proteasome inhibition in the cell. We show the efficacy of this strategy for in-depth analysis of the ubiquitinome profiles of several different cell types and of in vivo samples, such as brain tissue. This study presents an original addition to the toolbox for protein ubiquitination analysis to uncover the deep cellular ubiquitinome.

We present a method for the purification, detection, and identification of diGly peptides that originate from ubiquitinated proteins from complex biological samples. The presented method is reproducible, robust, and outperforms published methods with respect to the level of depth of the ubiquitinome analysis.

The posttranslational modification of proteins by the small protein ubiquitin is involved in many cellular events. After tryptic digestion of ...

Study on the Metabolism of Six Systemic Insecticides in a Newly Established Cell Suspension Culture Derived from Tea (Camellia Sinensis L.) Leaves

A platform for studying insecticide metabolism using in vitro tissues of tea plant was developed. Leaves from sterile tea plantlets were induced to form loose callus on Murashige and Skoog (MS) basal media with the plant hormones 2,4-dichlorophenoxyacetic acid (2,4-D, 1.0 mg L-1) and kinetin (KT, 0.1 mg L-1). Callus formed after 3 or 4 rounds of subculturing, each lasting 28 days. Loose callus (about 3 g) was then inoculated into B5 liquid media containing the same plant hormones and was cultured in a shaking incubator (120 rpm) in the dark at 25 &#177; 1 &#176;C. After 3&#8722;4 subcultures, a cell suspension derived from tea leaf was established at a subculture ratio ranging between 1:1 and 1:2 (suspension mother liquid: fresh medium). Using this platform, six insecticides (5 &#181;g mL-1 each thiamethoxam, imidacloprid, acetamiprid, imidaclothiz, dimethoate, and omethoate) were added into the tea leaf-derived cell suspension culture. The metabolism of the insecticides was tracked using liquid chromatography and gas chromatography. To validate the usefulness of the tea cell suspension culture, the metabolites of thiamethoxan and dimethoate present in treated cell cultures and intact plants were compared using mass spectrometry. In treated tea cell cultures, seven metabolites of thiamethoxan and two metabolites of dimethoate were found, while in treated intact plants, only two metabolites of thiamethoxam and one of dimethoate were found. The use of a cell suspension simplified the metabolic analysis compared to the use of intact tea plants, especially for a difficult matrix such as tea.

Study on the Metabolism of Six Systemic Insecticides in a Newly Established Cell Suspension Culture Derived from Tea Camellia Sinensis L. Leaves

This work presents a protocol for establishing a cell suspension culture derived from tea (Camellia sinensis L.) leaves that can be used to study the metabolism of external compounds that can be taken up by the whole plant, such as insecticides.

A platform for studying insecticide metabolism using in vitro tissues of tea plant was developed. Leaves from sterile tea plantlets were induced to form ...