This work was supported in part by the Natural Science Foundation of China (grant numbers 31471703, A0201300537 and 31671854 to J.V. and L.L., grant number 31470435 to G.Y.), and the 100 Foreign Talents Plan (grant number JSB2014012 to J.V.).

1. Sample collection
<ol>
	<li>Purchase different cultivars of fresh radish (Raphanus sativus L.).</li>
</ol>
2. Isolation of Protein from Radish
<ol>
	<li>Homogenize approximately 100 g of fresh radish with a kitchen blender for 10 min.</li>
	<li>Transfer the slurry to a 50 mL centrifuge tube and centrifuge at 14,000 &#215; g at 4 &#176;C for 20 min to remove the insoluble material.</li>
	<li>Transfer the supernatant carefully into a new 50 mL centrifuge tube and add an equal volume of 2 M trichloroacetic acid (TCA) solution. 
	NOTE: Adding TCA will precipitate soluble (glyco)proteins.</li>
	<li>Centrifuge at 14,000 &#215; g at 4 &#176;C for 30 min and remove the supernatant from the pelleted (glyco) proteins.</li>
	<li>Wash the pellet with 20 mL of deionized water and centrifuge at 14,000 &#215; g at 4 &#176;C for 5 min to remove soluble oligosaccharides and polysaccharides.</li>
	<li>Repeat step 2.5. four times.</li>
	<li>Re-suspend the pellets in 1 mL of deionized water and transfer to a fresh 1.5 mL centrifuge tube.</li>
</ol>
3. Preparation of N-Glycans
<ol>
	<li>Mix 50 &#181;L of protein solution from step 2.7. (equal to 5 g of fresh radish) with 0.2 mU of recombinant PNGase H+ in 10 mM acetic acid.</li>
	<li>Incubate the reaction mixture at 37 &#176;C for 12 h. After the incubation, centrifuge at 14,000 &#215; g for 5 min to remove the extra protein and enzyme.</li>
	<li>Transfer the supernatant to a fresh 1.5 mL centrifuge tube.</li>
</ol>
4. Purification of N-Glycans
<ol>
	<li>Prepare the solid-phase extraction (SPE) column to enrich the N-glycans and remove salts and other impurities from the reaction mixture, increasing the selectivity of the fluorogenic 2-aminobenzamide (2-AB) labeling agent for N-glycan derivatization.
	<ol>
		<li>Add 3 mL of deionized water to wash the column.</li>
		<li>Add 3 mL of 80% acetonitrile solution containing trifluoroacetic acid (TFA, 0.1% v/v) to active the SPE-column.</li>
		<li>Add 3 mL of deionized water to equilibrate the SPE-column.</li>
	</ol>
	</li>
	<li>Transfer the sample from step 3.3 onto the column and discard the flow-through.</li>
	<li>Add 1.5 mL of deionized water to wash the column and discard the flow-through.</li>
	<li>Elute the released N-glycans from the column using 1.5 mL of aqueous 20% acetonitrile solution, containing 0.1% TFA (v/v) into a 2 mL centrifuge tube.</li>
	<li>Remove the solvent by centrifugal evaporation at room temperature. Evaporate until the sample is completely dry.</li>
</ol>
5. Fluorescence Derivatization of N-Glycans
<ol>
	<li>Prepare 1 mL of 2-AB solution, consisting of 35 mM 2-AB and 0.1 M sodium cyanoborohydride in dimethyl sulfoxide/acetic acid solution (7:3, v/v).</li>
	<li>Add 5 &#181;L of 2-AB solution to the dried samples (step 4.5.) derived from six different radishes. Vortex each sample until completely dissolved.</li>
	<li>Incubate the mixture for 2 h at 65 &#176;C.</li>
	<li>Let the sample cool down to room temperature for 5 min, and add 5 &#181;L of deionized water and 40 &#181;L of acetonitrile. Centrifuge the tubes at 14,000 x g for 3 min.</li>
	<li>Transfer 48 &#181;L from the supernatant into a 300 &#181;L high-recovery HPLC vial. Store the derivatized N-glycan samples at -20 &#176;C for up to one month.</li>
</ol>
6. HILIC-UPLC profiling of N-glycans
<ol>
	<li>Analyze the samples using a standard UPLC system connected to an online fluorescence detectorset at the excitation/emission wavelengths of 330 nm/420 nm, respectively.</li>
	<li>Use a hydrophobic interaction liquid chromatography (HILIC)-UPLC glycan column at a column temperature of 60 &#176;C for the analysis.</li>
	<li>Prepare solvent A by diluting 50 mL of stock solution (1 M ammonium formate solution, pH 4.5) with 950 mL of liquid chromatography-mass spectrometry (LCMS)-grade water. Prepare the stock solution as follows:
	<ol>
		<li>Add 43 mL of formic acid to 700 mL of LCMS-grade H2O.</li>
		<li>Adjust the pH to 4.5 by dropwise addition of aqueous ammonia solution (25% w/w).</li>
		<li>Transfer the solvent to a measuring cylinder and fill up to 1000 mL with LCMS-grade H2O. Store at 4-6 &#176;C for up to 3 months.</li>
	</ol>
	</li>
	<li>Use LCMS-grade acetonitrile as solvent B.</li>
	<li>Separate N-glycans with the following gradient elution:
	<ol>
		<li>Start by adding 95% of solvent B into solvent A. Set the flow rate at 0.5 mL/min from 0 to 44.5 min.</li>
		<li>From 0 min to 6 min, gradually decrease the proportion of solvent B with a linear gradient to78%.</li>
		<li>From 6 min to 44.5 min, gradually decrease the proportion of solvent B with a linear gradient to 55.9%.</li>
		<li>From 44.5 min to 46.5 min, rapidly decrease the proportion of solvent B with a linear gradient from 55.9% to 0% and hold at 0% for 2 min, and initiate washing of the column. Reduce the flow rate to 0.25 mL/min from 44.5 to 55 min.</li>
		<li>Wash the column further by increasing solvent B to 95% from 48.5 min to 50.5 min and hold at 95% for 4.5 min.</li>
		<li>Re-equilibrate the column to the starting conditions of 95% solvent B at 0.5 mL/min from 50.5 to 57 min.</li>
	</ol>
	</li>
	<li>Inject 45 &#181;L of the sample into the UPLC system.</li>
	<li>Elute the N-glycans by UPLC with retention times between 15 and 40 min.</li>
	<li>Collect each observed UPLC peak fraction using 2 mL centrifuge tubes and dry the samples by centrifugal evaporation.</li>
	<li>Inject approximately 1 pmol of 2-AB labeled dextran standard (2&#8722;20 glucose units) to calibrate the plant-N-glycan profiling, and to assign their elution times into standardized glucose units.</li>
</ol>
7. MALDI-TOF MS Analysis
<ol>
	<li>Dissolve the samples from step 6.8 in 5 &#181;L of LCMS -grade water. Mix 1 &#181;L of the sample solution and 1 &#181;L of 6-aza-2-thiothymine (ATT) solution (0.3% w/v in 70% v/v aqueous acetonitrile), and pipette the mixture onto the MALDI-TOF sample carrier.</li>
	<li>Analyze the samples using a MALDI-TOF mass spectrometer instrument in positive ion mode by pressing the Start button.</li>
	<li>Analyze the mass spectra by using the accompanying MALDI-TOF-MS analysis software.</li>
	<li>Interpret the spectra using an open source glycan interpretation software19. Set the search parameters for 2-AB labeling, [M+Na]+, and set the accuracy parameter to 2.0 Da.</li>
</ol>

<ol>
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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=Rapid+sample+preparation+methodology+for+plant+N-.glycan+analysis+using+acid-stable+PNGase+H+.">Rapid sample preparation methodology for plant N-.glycan analysis using acid-stable PNGase H+.</a> Journal of Agricultural and Food Chemistry. 63 (48), 10550-10555 (2015).</li><li>Wang, T., Hu, X. -. C., Cai, Z. -. P., Voglmeir, J., Liu, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Qualitative+and+Quantitative+Analysis+of+Carbohydrate+Modification+on+Glycoproteins+from+seeds+of+Ginkgo+biloba.">Qualitative and Quantitative Analysis of Carbohydrate Modification on Glycoproteins from seeds of Ginkgo biloba.</a> Journal of Agricultural and Food Chemistry. 65 (35), 7669-7679 (2017).</li><li>Ceroni, A., 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=GlycoWorkbench:+a+tool+for+the+computer-assisted+annotation+of+mass+spectra+of+glycans.">GlycoWorkbench: a tool for the computer-assisted annotation of mass spectra of glycans.</a> Journal of Proteome Research. 7 (4), 1650-1659 (2008).</li></ol>

The authors have nothing to disclose.

The protocol we have presented here allows the comparison of the N-glycan profiles of various cultivars of radish. A significant advantage of this method compared to existing protocols is that no buffer changes between the enzymatic release of N-glycans and the derivatization reaction with 2-AB are required. The most critical step of this procedure is the purification of N-glycans using the SPE column, as failure to remove salts or other impurities in the reaction mixture may negatively impact ...

N-glycans in plants have drawn increased attention in recent years, as previous research has highlighted N-glycans as a potential source of immunological cross-reactions that may provoke allergic responses1,2. It has been demonstrated previously that N-glycans on plant glycoproteins can affect catalytic activity3,4, thermostability and folding5,6 or subcellular localization and secretion7. In order to correlate the glycan structures with their respective functions, N-glycans must first be released from glycoproteins either chemically or enzymatically. The classical chemical method for releasing both N- and O-glycans is &#946;-elimination, in which alkaline sample treatment is accompanied by reduction with borohydride to yield an alditol8. However, this procedure precludes labeling with a fluorophore and causes significant decay of monosaccharide units from the reducing end of the glycan structure. Chemical deglycosylation based on ammonium hydroxide/carbonate treatment is also a commonly used alternative method9. Neither of these chemical release methods degrades intact proteins, which allows mass spectrometric analysis of unlabeled glycan pools without the interference of peptide fragments in the same mass range. However, one drawback of these methods is the increased degradation rate of &#945;1,3-fucosylated N-glycans, a common carbohydrate structure found in plants10. Alternatively, enzymatic release methods using peptide:N-glycanases (PNGases, EC 3.5.1.52) are also widely applied. Recombinant PNGase F (from Flavobacterium meningosepticum) is the most common choice and permits the release of all types of N-glycans, except the structures bearing a core &#945;1,3 fucose11,12. Therefore, PNGase A (isolated from almond seeds) is usually used for the analysis of plant N-glycans13. However, this enzyme deglycosylates only proteolytically-derived glycopeptides, and is unable to deglycosylate native glycoproteins14. Hence, a multi-step sample workup is required before further analysis, which causes extensive loss of glycans, especially those of low abundance15.The overall goal of the method is to present an optimized workflow for N-glycan release and fluorescence labeling in a simple and robust manner. The underlying rationale is that PNGase H+, which was recently discovered in Terriglobus roseus and can be recombinantly expressed in E. coli, can hydrolyze N-glycans directly from the protein scaffold in acidic conditions16. A key advantage of using PNGase H+ over alternative methods is that fluorescent labeling reactions can be performed in the same reaction tube without changing the reaction buffers17,18. The simple preparation conditions and high recovery of low-abundance oligosaccharides make this method a valuable tool in the analysis of N-glycans. This protocol is suitable for the analysis of N-glycans from various plant species.

<table border="0" cellpadding="0" cellspacing="0" style="width:880px;" width="880">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">Chemicals:</td>
			<td style="width:123px;"></td>
			<td style="width:207px;"></td>
			<td style="width:204px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Trichloroacetic acid&#160;</td>
			<td>SCR, Shanghai</td>
			<td>80132618</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Acetic acid glacial</td>
			<td>Huada, Guangzhou</td>
			<td>64-19-7</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Acetonitrile</td>
			<td>General-reagent</td>
			<td>G80988C</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Trifluoroacetic acid</td>
			<td>Energy chemical</td>
			<td>W810031</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">2-aminobenzamide</td>
			<td>Heowns, Tianjin</td>
			<td>A41900</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Sodium cyanoborohydride</td>
			<td>J&#38;K Scientific Ltd</td>
			<td>314162</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Dimethyl sulfoxide</td>
			<td>Huada, Guangzhou</td>
			<td>67-68-5</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">2AB-labeled dextran ladder, 200 pmol</td>
			<td>Agilent Technologies</td>
			<td>AT-5190-6998</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">6-Aza-2-thiothymine&#160;</td>
			<td>Sigma</td>
			<td>275514</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Tools/Materials:</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Kitchen blender</td>
			<td>Bear, Guangzhou</td>
			<td>LLJ-A10T1</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Centrifuge</td>
			<td>Techcomp</td>
			<td>CT15RT</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Centrifugal Evaporator</td>
			<td>Hualida, Taicang</td>
			<td>LNG-T120</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">SPE column</td>
			<td>Supelco</td>
			<td>Supelclean ENVI Carb SPE column</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">MALDI-TOF mass spectrometer</td>
			<td>Bruker</td>
			<td>Autoflex</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">HPLC Analysis:</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">High-recovery HPLC vial</td>
			<td>Agilent Technologies</td>
			<td>&#160;# 5188-2788</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">HPLC System</td>
			<td>Shimadzu</td>
			<td>Nexera</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Fluorescence Detector for HPLC</td>
			<td>Shimadzu</td>
			<td>RF-20Axs&#160;</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Column oven</td>
			<td>Hengxin</td>
			<td>CO-2000</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">HPLC Column</td>
			<td>Waters</td>
			<td>Acquity UPLC BEH glycan column</td>
			<td>2.1 &#215; 150 mm, 1.7 &#956;m particle size</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">LCMS-grade Water</td>
			<td>Merck Millipore</td>
			<td>#WX00011</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">LCMS-grade Acetonitrile</td>
			<td>Merck Millipore</td>
			<td># 100029</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Formic acid</td>
			<td>Aladdin</td>
			<td>F112034</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Ammonia solution</td>
			<td>Aladdin</td>
			<td>A112080</td>
			<td></td>
		</tr>
	</tbody>
</table>

analysis of n-glycans from raphanus sativus cultivars using pngase h+

In recent years, the carbohydrate moieties of plants have received considerable attention, as they are a potential source of cross-reactive, allergy-provoking immune responses. In addition, carbohydrate structures also play a critical role in plant metabolism. Here, we present a simple and rapid method for preparing and analyzing N-glycans from different cultivars of radish (Raphanus sativus) using an N-glycanase specific for the release of plant-derived carbohydrate structures. To achieve this, crude trichloroacetic acid precipitates of radish homogenates were treated with PNGase H+, and labeled using 2-aminobenzamide as a fluorescent tag. The labeled N-glycan samples were subsequently analyzed by ultra performance liquid chromatography (UPLC) separation and matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry for a detailed structural evaluation and to quantify relative abundancies of the radish-derived N-glycan structures. This protocol can also be used for the analysis of N-glycans from various other plant species, and may be useful for further investigation of the function and effects of N-glycans on human health.

Figure 1 shows a schematic overview of the described protocol, including the isolation of (glyco-)proteins from radish, the preparation of N-glycans, the UPLC analysis, and the MALDI-TOF-MS analysis of these components. Figure 2 shows representative UPLC chromatograms of derivatized N-glycans of the analyzed radish cultivars. Figure 3 shows the obtained results of the 2AB-derivatize...

Watch this Scientific Journal Video about Analysis of N-glycans from Raphanus sativus Cultivars Using PNGase H+ at JoVE.com

Analysis of N-glycans from Raphanus sativus Cultivars Using PNGase H+

We describe a simple and rapid method for the preparation and analysis of N-glycans from different cultivars of radish (Raphanus sativus).

Analysis of N-glycans from Raphanus sativus Cultivars Using PNGase H+

In recent years, the carbohydrate moieties of plants have received considerable attention, as they are a potential source of cross-reactive, ...

analysis-of-n-glycans-from-raphanus-sativus-cultivars-using-pngase-h

Research

JoVE Journal

Biochemistry

6.5K Views.  Nanjing Agricultural University. We describe a simple and rapid method for the preparation and analysis of N-glycans from different cultivars of radish (Raphanus sativus).

Video: Analysis of N-glycans from Raphanus sativus Cultivars Using PNGase H+

Experimental Design for Laser Microdissection RNA-Seq: Lessons from an Analysis of Maize Leaf Development

Genes with important roles in development frequently have spatially and/or temporally restricted expression patterns. Often these gene transcripts are not detected or are not identified as differentially expressed (DE) in transcriptomic analyses of whole plant organs. Laser Microdissection RNA-Seq (LM RNA-Seq) is a powerful tool to identify genes that are DE in specific developmental domains. However, the choice of cellular domains to microdissect and compare, and the accuracy of the microdissections are crucial to the success of the experiments. Here, two examples illustrate design considerations for transcriptomics experiments; a LM RNA-seq analysis to identify genes that are DE along the maize leaf proximal-distal axis, and a second experiment to identify genes that are DE in liguleless1-R (lg1-R) mutants compared to wild-type. Key elements that contributed to the success of these experiments were detailed histological and in situ hybridization analyses of the region to be analyzed, selection of leaf primordia at equivalent developmental stages, the use of morphological landmarks to select regions for microdissection, and microdissection of precisely measured domains. This paper provides a detailed protocol for the analysis of developmental domains by LM RNA-Seq. The data presented here illustrate how the region selected for microdissection will affect the results obtained.

Many developmentally important genes have cell- or tissue-specific expression patterns. This paper describes LM RNA-seq experiments to identify genes that are differentially expressed at the maize leaf blade-sheath boundary and in lg1-R mutants compared to wild-type. The experimental considerations discussed here apply to transcriptomic analyses of other developmental phenomena.

Genes with important roles in development frequently have spatially and/or temporally restricted expression patterns. Often these gene transcripts are not ...

High-resolution Single Particle Analysis from Electron Cryo-microscopy Images Using SPHIRE

SPHIRE (SPARX for High-Resolution Electron Microscopy) is a novel open-source, user-friendly software suite for the semi-automated processing of single particle electron cryo-microscopy (cryo-EM) data. The protocol presented here describes in detail how to obtain a near-atomic resolution structure starting from cryo-EM micrograph movies by guiding users through all steps of the single particle structure determination pipeline. These steps are controlled from the new SPHIRE graphical user interface and require minimum user intervention. Using this protocol, a 3.5 &#197; structure of TcdA1, a Tc toxin complex from Photorhabdus luminescens, was derived from only 9500 single particles. This streamlined approach will help novice users without extensive processing experience and a priori structural information, to obtain noise-free and unbiased atomic models of their purified macromolecular complexes in their native state.

This paper presents a protocol for processing cryo-EM images using the software suite SPHIRE. The present protocol can be applied for nearly all single particle EM projects that target near-atomic resolution.

SPHIRE (SPARX for High-Resolution Electron Microscopy) is a novel open-source, user-friendly software suite for the semi-automated processing of single ...

Isolation of Intermediate Filament Proteins from Multiple Mouse Tissues to Study Aging-associated Post-translational Modifications

Intermediate filaments (IFs), together with actin filaments and microtubules, form the cytoskeleton &#8211; a critical structural element of every cell. Normal functioning IFs provide cells with mechanical and stress resilience, while a dysfunctional IF cytoskeleton compromises cellular health and has been associated with many human diseases. Post-translational modifications (PTMs) critically regulate IF dynamics in response to physiological changes and under stress conditions. Therefore, the ability to monitor changes in the PTM signature of IFs can contribute to a better functional understanding, and ultimately conditioning, of the IF system as a stress responder during cellular injury. However, the large number of IF proteins, which are encoded by over 70 individual genes and expressed in a tissue-dependent manner, is a major challenge in sorting out the relative importance of different PTMs. To that end, methods that enable monitoring of PTMs on IF proteins on an organism-wide level, rather than for isolated members of the family, can accelerate research progress in this area. Here, we present biochemical methods for the isolation of the total, detergent-soluble, and detergent-resistant fraction of IF proteins from 9 different mouse tissues (brain, heart, lung, liver, small intestine, large intestine, pancreas, kidney, and spleen). We further demonstrate an optimized protocol for rapid isolation of IF proteins by using lysing matrix and automated homogenization of different mouse tissues. The automated protocol is useful for profiling IFs in experiments with high sample volume (such as in disease models involving multiple animals and experimental groups). The resulting samples can be utilized for various downstream analyses, including mass spectrometry-based PTM profiling. Utilizing these methods, we provide new data to show that IF proteins in different mouse tissues (brain and liver) undergo parallel changes with respect to their expression levels and PTMs during aging.

In this method, we present biochemical procedures for rapid and efficient isolation of intermediate filament (IF) proteins from multiple mouse tissues. Isolated IFs can be used to study changes in post-translational modifications by mass spectrometry and other biochemical assays.

Intermediate filaments (IFs), together with actin filaments and microtubules, form the cytoskeleton &#8211; a critical structural element of every cell. ...

Dissection of Human Retina and RPE-Choroid for Proteomic Analysis

The human retina is composed of the sensory neuroretina and the underlying retinal pigmented epithelium (RPE), which is firmly complexed to the vascular choroid layer. Different regions of the retina are anatomically and molecularly distinct, facilitating unique functions and demonstrating differential susceptibility to disease. Proteomic analysis of each of these regions and layers can provide vital insights into the molecular process of many diseases, including Age-Related Macular Degeneration (AMD), diabetes mellitus, and glaucoma. However, separation of retinal regions and layers is essential before quantitative proteomic analysis can be accomplished. Here, we describe a method for dissection and collection of the foveal, macular, and peripheral retinal regions and underlying RPE-choroid complex, involving regional punch biopsies and manual removal of tissue layers from a human eye.One-dimensional SDS-PAGE as well as downstream proteomic analysis, such as liquid chromatography-tandem mass spectrometry (LC-MS/MS), can be used to identify proteins in each dissected retinal layer, revealing molecular biomarkers for retinal disease.

The human retina is composed of functionally and molecularly distinct regions, including the fovea, macula, and peripheral retina. Here, we describe a method using punch biopsies and manual removal of tissue layers from a human eye to dissect and collect these distinct retinal regions for downstream proteomic analysis.

The human retina is composed of the sensory neuroretina and the underlying retinal pigmented epithelium (RPE), which is firmly complexed to the vascular ...

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 ...

Dynamic Proteomic and miRNA Analysis of Polysomes from Isolated Mouse Heart After Langendorff Perfusion

Studies in dynamic changes in protein translation require specialized methods. Here we examined changes in newly-synthesized proteins in response to ischemia and reperfusion using the isolated perfused mouse heart coupled with polysome profiling. To further understand the dynamic changes in protein translation, we characterized the mRNAs that were loaded with cytosolic ribosomes (polyribosomes or polysomes) and also recovered mitochondrial polysomes and compared mRNA and protein distribution in the high-efficiency fractions (numerous ribosomes attached to mRNA), low-efficiency (fewer ribosomes attached) which also included mitochondrial polysomes, and the non-translating fractions. miRNAs can also associate with mRNAs that are being translated, thereby reducing the efficiency of translation, we examined the distribution of miRNAs across the fractions. The distribution of mRNAs, miRNAs, and proteins was examined under basal perfused conditions, at the end of 30 min of global no-flow ischemia, and after 30 min of reperfusion. Here we present the methods used to accomplish this analysis&#8212;in particular, the approach to optimization of protein extraction from the sucrose gradient, as this has not been described before&#8212;and provide some representative results.

Here we present a protocol to perform polysome profiling on the isolated perfused mouse heart. We describe methods for heart perfusion, polysome profiling, and analysis of the polysome fractions with respect to mRNAs, miRNAs, and the polysome proteome.

Studies in dynamic changes in protein translation require specialized methods. Here we examined changes in newly-synthesized proteins in response to ...

Analysis of Fucosylated Human Milk Trisaccharides in Biotechnological Context Using Genetically Encoded Biosensors

Human milk oligosaccharides (HMOs) are complex carbohydrate components of human breast milk that exhibit plentiful benefits on infant health. However, optimization of their biotechnological synthesis is limited by the relatively low throughput of detection and quantification of monosaccharide and linkages. Conventional techniques of glycan analysis include chromatographic/mass-spectrometric methods with throughput on the order of hundreds of samples per day without automation. We demonstrate here, a genetically encoded bacterial biosensor for the high-throughput, linkage-specific detection and quantification of the fucosylated HMO structures, 2&#8217;-fucosyllactose and 3-fucosyllactose, which we achieved via heterologous expression of fucosidases. As the presence of lactose in milk or in biotechnological processes could lead to false positives, we also demonstrate the reduction of signal from lactose using different strategies. Due to the high throughput of this technique, many reaction conditions or bioreactor parameters could be assayed in parallel in a matter of hours, allowing for the optimization of HMO manufacturing.

We describe here the high-throughput detection and quantification of fucosylated human milk oligosaccharides (HMOs) using a whole-cell biosensor. We also demonstrate here, the adaptation of this platform towards analysis of HMO production strains, focusing on improving the signal to noise ratio.

Human milk oligosaccharides (HMOs) are complex carbohydrate components of human breast milk that exhibit plentiful benefits on infant health. However, ...

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 ...

Isolation of Histone from Sorghum Leaf Tissue for Top Down Mass Spectrometry Profiling of Potential Epigenetic Markers

Histones belong to a family of highly conserved proteins in eukaryotes. They pack DNA into nucleosomes as functional units of chromatin. Post-translational modifications (PTMs) of histones, which are highly dynamic and can be added or removed by enzymes, play critical roles in regulating gene expression. In plants, epigenetic factors, including histone PTMs, are related to their adaptive responses to the environment. Understanding the molecular mechanisms of epigenetic control can bring unprecedented opportunities for innovative bioengineering solutions. Herein, we describe a protocol to isolate the nuclei and purify histones from sorghum leaf tissue. The extracted histones can be analyzed in their intact forms by top-down mass spectrometry (MS) coupled with online reversed-phase (RP) liquid chromatography (LC). Combinations and stoichiometry of multiple PTMs on the same histone proteoform can be readily identified. In addition, histone tail clipping can be detected using the top-down LC-MS workflow, thus, yielding the global PTM profile of core histones (H4, H2A, H2B, H3). We have applied this protocol previously to profile histone PTMs from sorghum leaf tissue collected from a large-scale field study, aimed at identifying epigenetic markers of drought resistance. The protocol could potentially be adapted and optimized for chromatin immunoprecipitation-sequencing (ChIP-seq), or for studying histone PTMs in similar plants.

The protocol has been developed to effectively extract intact histones from sorghum leaf materials for profiling of histone post-translational modifications that can serve as potential epigenetic markers to aid engineering drought resistant crops.

Histones belong to a family of highly conserved proteins in eukaryotes. They pack DNA into nucleosomes as functional units of chromatin. ...

Preparation of Sample Support Films in Transmission Electron Microscopy using a Support Floatation Block

Structure determination by cryo-electron microscopy (cryo-EM) has rapidly grown in the last decade; however, sample preparation remains a significant bottleneck. Macromolecular samples are ideally imaged directly from random orientations in a thin layer of vitreous ice. However, many samples are refractory to this, and protein denaturation at the air-water interface is a common problem. To overcome such issues, support films-including amorphous carbon, graphene, and graphene oxide-can be applied to the grid to provide a surface which samples can populate, reducing the probability of particles experiencing the deleterious effects of the air-water interface. The application of these delicate supports to grids, however, requires careful handling to prevent breakage, airborne contamination, or extensive washing and cleaning steps. A recent report describes the development of an easy-to-use floatation block that facilitates wetted transfer of support films directly to the sample. Use of the block minimizes the number of manual handling steps required, preserving the physical integrity of the support film, and the time over which hydrophobic contamination can accrue, ensuring that a thin film of ice can still be generated. This paper provides step-by-step protocols for the preparation of carbon, graphene, and graphene oxide supports for EM studies.

Sample preparation for cryo-electron microscopy (cryo-EM) is a significant bottleneck in the structure determination workflow of this method. Here, we provide detailed methods for using an easy-to-use, three-dimensionally printed block for the preparation of support films to stabilize samples for transmission EM studies.

Structure determination by cryo-electron microscopy (cryo-EM) has rapidly grown in the last decade; however, sample preparation remains a significant ...