Name: fast and simplified method for high through-put isolation of mirna from highly purified high density lipoprotein
Uploaded: 2016-07-27T13:00:00
Description: Watch this Scientific Journal Video about Fast and Simplified Method for High Through-put Isolation of miRNA from Highly Purified High Density Lipoprotein at JoVE.com

This work was supported, in whole or in part, by NIH Grants R01 AA 020758-04, U01DK 061731-13 and T32 DK 007150-38 to AJS and T32 DK 007150-38 to AA. This is original work and is not under consideration elsewhere for publication.

1. Collection of Blood Samples
<ol>
	<li>Collect fasting peripheral venous blood samples into 10 ml plastic tubes containing anticoagulant Ethylenediaminetetraacetic acid (EDTA) (which has several advantages over other anticoagulants) by standard venipuncture of a prominent vein in the antecubital fossa.</li>
	<li>Centrifuge the blood samples at 1,600 x g for 20 min at 4 &#176;C in a tabletop centrifuge to obtain plasma free of red blood cells and small amounts of RNA.</li>
	<li>Sequentially centrifuge the supernatant ...

<ol>
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M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Physicochemical+properties+of+apolipoprotein+(a)+and+lipoprotein+(a-)+derived+from+the+dissociation+of+human+plasma+lipoprotein+(a).">Physicochemical properties of apolipoprotein (a) and lipoprotein (a-) derived from the dissociation of human plasma lipoprotein (a).</a> J Biol Chem. 261, 8712-8718 (1986).</li><li>Brownie, 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=The+elimination+of+primer-dimer+accumulation+in+PCR.">The elimination of primer-dimer accumulation in PCR.</a> Nucleic Acids Res. 25, 3235-3241 (1997).</li><li>Alton, E., Inyoul, L., Leroy, H., David, G., Kai, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Extracellular+microRNA:+a+new+source+of+biomarkers.">Extracellular microRNA: a new source of biomarkers.</a> Mutat Res. 717 (1-2), 85-90 (2011).</li><li>Stefanie, S. 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Identification of novel biomarkers from blood will aid in the clinical diagnosis and prognosis of various diseases. MicroRNAs have known to possess all the qualities of biomarkers and have been shown in various studies 14-17. In this study we have demonstrated rapid and simple easy method to isolate miRNA from plasma HDL. Conventional density gradient ultra-centrifugation method of isolation of VLDL, LDL and HDL depends on accurate sampling of plasma, precise preparation of the buffer solution, measurement of ...

MicroRNAs are endogenous non-coding tiny RNA species that are highly conserved and are considered key players in the regulation of various biological processes by degrading or repressing specific target messenger RNAs1. Because miRNAs act intracellularly they have been explored as tissue-derived biomarkers which led to the discovery of tissue-specific functions of these miRNA. However, miRNAs are also found extracellularly either associated with proteins or in exosomes/micro vesicles that effectively can shield them from degradation by extracellular RNases2. More recent studies have shown that the protective effect of HDL may not be closely linked to its capability to promote cholesterol efflux but rather to its non-cholesterol cargo, in particularly as a circulating miRNAs carrier 3, 4. These miRNAs may not only modulate lipid metabolism but are also associated with anti-inflammatory, antioxidant and antithrombotic effects of the HDL-miRNA complex 5, 6.
To further explore the role of miRNAs carried in HDL particles, a simple and easy protocol needs to be established for miRNA extraction from isolated highly purified HDL for use in clinical routine. Numerous methods have been described to isolate HDL. These methods are either very time consuming or require large volume of plasma that may require sample pooling, extensive dialysis for desalting isolated lipoproteins and they do not completely remove exosomes as a source of miRNAs3, respectively. Here we describe a simple and rapid method that can isolate miRNA from highly purified HDL utilizing small volume of blood samples on a larger scale. We believe that this method may serve as good reference to promote research into the role of circulating miRNAs and in particular the role of HDL in facilitating communication between various cells and organs.

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		<tr height="21">
			<td height="21" style="height:21px;width:348px;">Plastic Vacutainer Lavender K2EDTA tubes&#160;</td>
			<td style="width:279px;">Becton, Dickinson and Company</td>
			<td style="width:172px;">366643</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Centrifuge</td>
			<td>Thermo Scientific, Sorvall Legend X1R&#160;</td>
			<td style="width:172px;">75004261</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Densito 30PX densitometer</td>
			<td>Mettler Toledo</td>
			<td style="width:172px;">MT51324450</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">ExoQuick solution&#160;</td>
			<td>Invitrogen</td>
			<td style="width:172px;">4484451</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Polycarbonate thick-walled ultracentrifuge tube</td>
			<td>Thermo Scientific</td>
			<td style="width:172px;">O3237</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Sorvall WX100 ultracentrifuge&#160;</td>
			<td>Thermo Scientific</td>
			<td style="width:172px;">46902</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Fat Red 7B&#160;</td>
			<td>Sigma-Aldrich</td>
			<td style="width:172px;">201618</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">&#946;-mercaptoethanol&#160;</td>
			<td>Sigma-Aldrich</td>
			<td style="width:172px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Amicon Ultra-15 Centrifugal filter devices 10K</td>
			<td>Millipore</td>
			<td style="width:172px;">UFC901008</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Amicon Ultra-centrifugal filter devices 3K</td>
			<td>Millipore</td>
			<td style="width:172px;">UFC800308</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">QuickGel Lipo kit&#160;</td>
			<td>Helena Laboratories&#160;</td>
			<td style="width:172px;">3344,3544T</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Human lipoprotein standards for VLDL, LDL and HDL</td>
			<td>LipoTrol; Helena Laboratories</td>
			<td style="width:172px;">5069</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Rep Prep buffer&#160;</td>
			<td>Helena Laboratories&#160;</td>
			<td style="width:172px;">3100</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">RNeasy MinElute spin columns&#160;</td>
			<td>Qiagen</td>
			<td style="width:172px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">NanoDrop 1000 analyzer</td>
			<td>Thermo Scientific</td>
			<td style="width:172px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">miScript II RT Kit&#160;</td>
			<td>Qiagen</td>
			<td style="width:172px;">218161</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">CFX96 Touch real-time PCR detection system</td>
			<td>BioRad</td>
			<td style="width:172px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:348px;">miRNeasy Serum/Plasma Kit</td>
			<td style="width:279px;">QIAGEN</td>
			<td style="width:172px;">217184</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:348px;">miScript Primer Assays</td>
			<td style="width:279px;">QIAGEN</td>
			<td style="width:172px;">141078139</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:348px;">miScript SYBR Green PCR Kit&#160;</td>
			<td style="width:279px;">QIAGEN</td>
			<td style="width:172px;">218073</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:348px;">miRNeasy Serum/Plasma Spike-In Control</td>
			<td style="width:279px;">QIAGEN</td>
			<td style="width:172px;">219610</td>
			<td></td>
		</tr>
	</tbody>
</table>

fast and simplified method for high through-put isolation of mirna from highly purified high density lipoprotein

Small non-coding RNAs (miRNAs) have been implicated in a variety of human diseases including metabolic syndromes. They may be utilized as biomarkers for diagnosis and prognosis or may serve as targets for drug development, respectively. Recently it has been shown that miRNAs are carried in lipoproteins, particularly high density lipoproteins (HDL) and are delivered to recipient cells for uptake. This raises the possibility that miRNAs play a critical and pivotal role in cellular and organ function via regulation of gene expression as well as messenger for cell-cell communications and crosstalk between organs. Current methods for miRNA isolation from purified HDL are impractical when utilizing small samples on a large scale. This is largely due to the time consuming and laborious methods used for lipoprotein isolation. We have developed a simplified approach to rapidly isolate purified HDL suitable for miRNA analysis from plasma samples. This method should facilitate investigations into the role of miRNAs in health and disease and in particular provide new insights into the variety of biological functions, outside of the reverse cholesterol transport, that have been ascribed to HDL. Also, the miRNA species which are present in HDL can provide valuable information of clinical biomarkers for diagnosis of various diseases.

Isolation of High Density Lipoprotein After Removal of Exosomes 
To obtain miRNA from highly purified HDL it is necessary to remove exosomes that represent a source of miRNA contamination7. This was done prior to density gradient ultracentrifugation with a commercially available kit. For practical purposes a three step standard density gradient ultracentrifugation protocol developed by commercial company was modified (Figure 1</str...

Watch this Scientific Journal Video about Fast and Simplified Method for High Through-put Isolation of miRNA from Highly Purified High Density Lipoprotein at JoVE.com

Fast and Simplified Method for High Through-put Isolation of miRNA from Highly Purified High Density Lipoprotein

MicroRNAs play an important regulatory role and are emerging as novel therapeutic targets for various human diseases. It has been shown that miRNAs are carried in high density lipoproteins. We have developed a simplified method to rapidly isolate purified HDL suitable for miRNA analysis from human plasma.

Small non-coding RNAs (miRNAs) have been implicated in a variety of human diseases including metabolic syndromes. They may be utilized as biomarkers for ...

The overall goal of this method is to develop a simplified approach to rapidly isolate purified high density lipoproteins from human blood plasma for micro RNA analysis. This method can help answer key questions in hepatology and cardiology, such as understanding the molecular mechanisms and protective functions of high density lipoproteins. Some main advantages of this technique is that purified HDL micro RNA come pre-isolated from less volume of samples within a short period of time.In this protocol, plasma is obtained from fasting peripheral venous blood samples by multiple centrifugation steps as described in the protocol text. Transfer the plasma to a new tube. And measure the density of the plasma using a densitometer at room temperature, per the manufacturer's instructions.To remove the circulating exosomes that represent a source of micro RNA contamination, add 252 microliters of exosome precipitation solution to one milliliter of plasma. And incubate for 30 minutes at four degrees Celsius. Then centrifuge the mixture for 30 minutes to pellet out the exosomes.Transfer one milliliter of the resulting supernatant to a polycarbonate thick walled ultracentrifuge tube for further processing, as demonstrated in the next video segment. Isolation of high density lipoproteins, or HDL, is accomplished by a three step density gradient ultracentrifugation protocol, that involves a sequential isolation of very low density lipoproteins, or VLDL, low density lipoproteins, or LDL, and HDL. The three different density solutions, A, B, and C, must be prepared fresh, following the procedure described in the protocol text.In a 6.5 milliliter polycarbonate thick walled ultracentrifuge tube, mix one milliliter of plasma and 200 microliters of nuclease-free Fat Red 7B. Then, carefully layer five milliliters of solution A on top of the mixture. If needed, add additional Fat Red 7B on top of solution A to balance the weight of each tube.Load the tubes into a pre-chilled rotor. Place the rotor into a floor centrifuge and centrifuge for two hours. At the end of the run, two layers should be visible.Remove 1.5 milliliters of the top layer, representing the VLDL fraction. And store it four degrees Celsius. Use a pipette to transfer four milliliters from the bottom of the tube to a new 50 milliliter tube.This contains the LDL and HDL fraction. The next step is the isolation of LDL. Mix two milliliters of solution B and 100 microliters of nuclease-free Fat Red 7B into the tube containing the LDL and HDL fraction.Put on ice for five to ten minutes. Transfer 6.5 milliliters of the mixed sample into a polycarbonate thick walled ultracentrifuge tube. Load the tube into a pre-chilled rotor and centrifuge for three hours.When the centrifugation is complete, remove 1.5 milliliters of the top layer, representing the LDL fraction and keep at four degrees Celsius. Transfer four milliliters from the bottom of the tube, containing the HDL fraction to a 50 milliliter sterile tube. The third step is the isolation of HDL.Mix two milliliters of solution C, 100 microliters of nuclease-free Fat Red 7B, and 15 microliters of 98%beta mercaptoethanol into the tube, containing the HDL fraction. Check the density of the mixture. Load the tube into a pre-chilled rotor and centrifuge for three hours.After that, remove two milliliters of the top layer, representing the HDL fraction, and keep at four degrees Celsius. Excessive salt must be removed from the lipoprotein fractions to avoid interference with subsequent agarose gel electrophoresis and PCR. In this video, desalting and concentration will be demonstrated for only the HDL fraction.Add 13 milliliters of cold PBS to the HDL fraction and transfer to a centrifugal filter device with the molecular weight cut-off of 10K. Centrifuge in a swinging bucket rotor, at 4000 times g, and four degrees Celsius, for 30 minutes. Desalt the HDL fraction, a second time, using 13 milliliters of cold PBS, and centrifuging as before.After centrifugation, remove the lipoprotein containing solutes, and keep at four degrees Celsius. To assess the quality and purity of the isolated lipoproteins, agarose gel electrophoresis was performed with human lipoprotein standards, included as a size reference. Representative results from an isolation, without beta mercaptoethanol, showed that the HDL fraction is devoid of any contamination of VLDL and exhibits typical alpha mobility.However, the HDL fraction also shows traces of beta mobility due to contamination with lipoproteins. The addition of beta mercaptoethanol to solution C, during the last centrifugation step, effectively removes all contaminating lipoproteins from the HDL fraction. To demonstrate the feasibility of quantifying micro RNAs, carried in human HDL, purified with this method, two different micro RNAs were amplified by real-time quantitative PCR.In these amplification plots, the horizontal lines represent the detection threshold. Representative real-time PCR data from isolated HDL, obtained from six samples, showed the consistent detection of both micro RNAs. Lastly, melting curve analyses clearly show a distinct single peak for both micro RNAs, consistent with specific amplification in the preceding PCR.Once mastered, this technique can be done in nine hours, together with the desalting procedures, if it is done properly. While attempting this procedure, it is important to work at four to eight degrees centigrade, at all times. And to adjust the density of each lipoprotein fraction before ultracentrifugation.Following this procedure, other methods, such as electron microscopy, can be performed in order to answer additional questions, like the purity of HDL. After its development, this technique will allow researchers, in the field of metabolic syndrome, to explore HDL-associated micro RNAs as bio markers, in humans with suspected fatty liver disease. It may also be used to better understand the function of HDL and the molecular mechanisms by which it alters cell biology.

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Biology

A Neuronal and Astrocyte Co-Culture Assay for High Content Analysis of Neurotoxicity

High Content Analysis (HCA) assays combine cells and detection reagents with automated imaging and powerful image analysis algorithms, allowing measurement of multiple cellular phenotypes within a single assay. In this study, we utilized HCA to develop a novel assay for neurotoxicity. Neurotoxicity assessment represents an important part of drug safety evaluation, as well as being a significant focus of environmental protection efforts. Additionally, neurotoxicity is also a well-accepted in vitro marker of the development of neurodegenerative diseases such as Alzheimer's and Parkinson's diseases. Recently, the application of HCA to neuronal screening has been reported. By labeling neuronal cells with &beta;III-tubulin, HCA assays can provide high-throughput, non-subjective, quantitative measurements of parameters such as neuronal number, neurite count and neurite length, all of which can indicate neurotoxic effects. However, the role of astrocytes remains unexplored in these models. Astrocytes have an integral role in the maintenance of central nervous system (CNS) homeostasis, and are associated with both neuroprotection and neurodegradation when they are activated in response to toxic substances or disease states. GFAP is an intermediate filament protein expressed predominantly in the astrocytes of the CNS. Astrocytic activation (gliosis) leads to the upregulation of GFAP, commonly accompanied by astrocyte proliferation and hypertrophy. This process of reactive gliosis has been proposed as an early marker of damage to the nervous system. The traditional method for GFAP quantitation is by immunoassay. This approach is limited by an inability to provide information on cellular localization, morphology and cell number. We determined that HCA could be used to overcome these limitations and to simultaneously measure multiple features associated with gliosis - changes in GFAP expression, astrocyte hypertrophy, and astrocyte proliferation - within a single assay. In co-culture studies, astrocytes have been shown to protect neurons against several types of toxic insult and to critically influence neuronal survival. Recent studies have suggested that the use of astrocytes in an in vitro neurotoxicity test system may prove more relevant to human CNS structure and function than neuronal cells alone. Accordingly, we have developed an HCA assay for co-culture of neurons and astrocytes, comprised of protocols and validated, target-specific detection reagents for profiling &beta;III-tubulin and glial fibrillary acidic protein (GFAP). This assay enables simultaneous analysis of neurotoxicity, neurite outgrowth, gliosis, neuronal and astrocytic morphology and neuronal and astrocytic development in a wide variety of cellular models, representing a novel, non-subjective, high-throughput assay for neurotoxicity assessment. The assay holds great potential for enhanced detection of neurotoxicity and improved productivity in neuroscience research and drug discovery.

This article describes a novel protocol and reagent set designed for sensitive measurement of neurotoxic effects of compounds and treatments on co-cultures of neurons and astrocytes using high content analysis. Results demonstrate that high content analysis represents an exciting novel technology for neurotoxicity assessment.

High Content Analysis (HCA) assays combine cells and detection reagents with automated imaging and powerful image analysis algorithms, allowing ...

Quantification of dsDNA using the Hitachi F-7000 Fluorescence Spectrophotometer and PicoGreen Dye

Quantification of DNA, especially in small concentrations, is an important task with a wide range of biological applications including standard molecular biology assays such as synthesis and purification of DNA, diagnostic applications such as quantification of DNA amplification products, and detection of DNA molecules in drug preparations. During this video we will demonstrate the capability of the Hitachi F-7000 Fluorescence Spectrophotometer equipped with a Micro Plate Reader accessory to perform dsDNA quantification using Molecular Probes Quant-it PicoGreen dye reagent kit.
The F-7000 Fluorescence Spectrophotometer offers high sensitivity and high speed measurements. It is a highly flexible system capable of measuring fluorescence, luminescence, and phosphorescence. Several measuring modes are available, including wavelength scan, time scan, photometry and 3-D scan measurement. The spectrophotometer has sensitivity in the range of 50 picomoles of fluorescein when using a 300 &#956;L sample volume in the microplate, and is capable of measuring scan speeds of 60,000 nm/minute. It also has a wide dynamic range of up to 5 orders of magnitude which allows for the use of calibration curves over a wide range of concentrations. The optical system uses all reflective optics for maximum energy and sensitivity. The standard wavelength range is 200 to 750 nm, and can be extended to 900 nm when using one of the optional near infrared photomultipliers. The system allows optional temperature control for the plate reader from 5 to 60 degrees Celsius using an optional external temperature controlled liquid circulator. The microplate reader allows for the use of 96 well microplates, and the measuring speed for 96 wells is less than 60 seconds when using the kinetics mode.
Software controls for the F-7000 and Microplate Reader are also highly flexible. Samples may be set in either column or row formats, and any combination of wells may be chosen for sample measurements. This allows for optimal utilization of the microplate. Additionally, the software allows importing micro plate sample configurations created in Excel and saved in comma separated values, or "csv" format. Microplate measuring configurations can be saved and recalled by the software for convenience and increased productivity. Data results can be output to a standard report, to Excel, or to an optional Report Generator Program.

Demonstration of quantification of dsDNA using Molecular Probes PicoGreen dye and Hitachi F-7000 Fluorescence Spectrophotometer equipped with a microplate reader accessory.

Quantification of DNA, especially in small concentrations, is an important task with a wide range of biological applications including standard molecular ...

Absolute Quantum Yield Measurement of Powder Samples

Measurement of fluorescence quantum yield has become an important tool in the search for new solutions in the development, evaluation, quality control and research of illumination, AV equipment, organic EL material, films, filters and fluorescent probes for bio-industry.
Quantum yield is calculated as the ratio of the number of photons absorbed, to the number of photons emitted by a material. The higher the quantum yield, the better the efficiency of the fluorescent material.
For the measurements featured in this video, we will use the Hitachi F-7000 fluorescence spectrophotometer equipped with the Quantum Yield measuring accessory and Report Generator program. All the information provided applies to this system. 
Measurement of quantum yield in powder samples is performed following these steps:
<ol>
 <li>Generation of instrument correction factors for the excitation and emission monochromators. This is an important requirement for the correct measurement of quantum yield. It has been performed in advance for the full measurement range of the instrument and will not be shown in this video due to time limitations.</li>
 <li>Measurement of integrating sphere correction factors. The purpose of this step is to take into consideration reflectivity characteristics of the integrating sphere used for the measurements.</li>
 <li>Reference and Sample measurement using direct excitation and indirect excitation.</li>
 <li>Quantum Yield calculation using Direct and Indirect excitation. Direct excitation is when the sample is facing directly the excitation beam, which would be the normal measurement setup. However, because we use an integrating sphere, a portion of the emitted photons resulting from the sample fluorescence are reflected by the integrating sphere and will re-excite the sample, so we need to take into consideration indirect excitation. This is accomplished by measuring the sample placed in the port facing the emission monochromator, calculating indirect quantum yield and correcting the direct quantum yield calculation.</li>
 <li>Corrected quantum yield calculation.</li>
 <li>Chromaticity coordinates calculation using Report Generator program.</li>
</ol>
The Hitachi F-7000 Quantum Yield Measurement System offer advantages for this
application, as follows:
<ul>
 <li>High sensitivity (S/N ratio 800 or better RMS). Signal is the Raman band of water measured under the following conditions: Ex wavelength 350 nm, band pass Ex and Em 5 nm, response 2 sec), noise is measured at the maximum of the Raman peak. High sensitivity allows measurement of samples even with low quantum yield. Using this system we have measured quantum yields as low as 0.1 for a sample of salicylic acid and as high as 0.8 for a sample of magnesium tungstate.</li>
 <li>Highly accurate measurement with a dynamic range of 6 orders of magnitude allows for measurements of both sharp scattering peaks with high intensity, as well as broad fluorescence peaks of low intensity under the same conditions. </li>
 <li>High measuring throughput and reduced light exposure to the sample, due to a high scanning speed of up to 60,000 nm/minute and automatic shutter function. </li>
 <li>Measurement of quantum yield over a wide wavelength range from 240 to 800 nm.</li>
 <li>Accurate quantum yield measurements are the result of collecting instrument spectral response and integrating sphere correction factors before measuring the sample.</li>
 <li>Large selection of calculated parameters provided by dedicated and easy to use software.
</li>
</ul> 
During this video we will measure sodium salicylate in powder form which is known to have a quantum yield value of 0.4 to 0.5.

In this video we will demonstrate measuring and calculating absolute quantum yield and chromaticity coordinates directly in powder samples using the Hitachi F-7000 Quantum Yield Measuring System.

Measurement of fluorescence quantum yield has become an important tool in the search for new solutions in the development, evaluation, quality control and ...

High-throughput Crystallization of Membrane Proteins Using the Lipidic Bicelle Method

Membrane proteins (MPs) play a critical role in many physiological processes such as pumping specific molecules across the otherwise impermeable membrane bilayer that surrounds all cells and organelles. Alterations in the function of MPs result in many human diseases and disorders; thus, an intricate understanding of their structures remains a critical objective for biological research. However, structure determination of MPs remains a significant challenge often stemming from their hydrophobicity. 
MPs have substantial hydrophobic regions embedded within the bilayer. Detergents are frequently used to solubilize these proteins from the bilayer generating a protein-detergent micelle that can then be manipulated in a similar manner as soluble proteins. Traditionally, crystallization trials proceed using a protein-detergent mixture, but they often resist crystallization or produce crystals of poor quality. These problems arise due to the detergent&prime;s inability to adequately mimic the bilayer resulting in poor stability and heterogeneity. In addition, the detergent shields the hydrophobic surface of the MP reducing the surface area available for crystal contacts. To circumvent these drawbacks MPs can be crystallized in lipidic media, which more closely simulates their endogenous environment, and has recently become a de novo technique for MP crystallization.
Lipidic cubic phase (LCP) is a three-dimensional lipid bilayer penetrated by an interconnected system of aqueous channels1. Although monoolein is the lipid of choice, related lipids such as monopalmitolein and monovaccenin have also been used to make LCP2. MPs are incorporated into the LCP where they diffuse in three dimensions and feed crystal nuclei. A great advantage of the LCP is that the protein remains in a more native environment, but the method has a number of technical disadvantages including high viscosity (requiring specialized apparatuses) and difficulties in crystal visualization and manipulation3,4. Because of these technical difficulties, we utilized another lipidic medium for crystallization-bicelles5,6 (Figure 1). Bicelles are lipid/amphiphile mixtures formed by blending a phosphatidylcholine lipid (DMPC) with an amphiphile (CHAPSO) or a short-chain lipid (DHPC). Within each bicelle disc, the lipid molecules generate a bilayer while the amphiphile molecules line the apolar edges providing beneficial properties of both bilayers and detergents. Importantly, below their transition temperature, protein-bicelle mixtures have a reduced viscosity and are manipulated in a similar manner as detergent-solubilized MPs, making bicelles compatible with crystallization robots. 
Bicelles have been successfully used to crystallize several membrane proteins5,7-11 (Table 1). This growing collection of proteins demonstrates the versatility of bicelles for crystallizing both alpha helical and beta sheet MPs from prokaryotic and eukaryotic sources. Because of these successes and the simplicity of high-throughput implementation, bicelles should be part of every membrane protein crystallographer&prime;s arsenal. In this video, we describe the bicelle methodology and provide a step-by-step protocol for setting up high-throughput crystallization trials of purified MPs using standard robotics.

Bicelles are lipid/amphiphile mixtures that maintain membrane proteins (MPs) within a lipid bilayer but have unique phase behavior that facilitates high-throughput screening by crystallization robots. This technique has successfully produced a number of high-resolution structures from both prokaryotic and eukaryotic sources. This video describes protocols for generating the lipidic bicelle mixture, incorporating MPs into the bicelle mixture, setting up crystallizations trials (manually as well as robotically) and harvesting crystals from the medium.

Membrane proteins (MPs) play a critical role in many physiological processes such as pumping specific molecules across the otherwise impermeable membrane ...

Rapid Fibroblast Removal from High Density Human Embryonic Stem Cell Cultures

Mouse embryonic fibroblasts (MEFs) were used to establish human embryonic stem cells (hESCs) cultures after blastocyst isolation1. This feeder system maintains hESCs from undergoing spontaneous differentiation during cell expansion. However, this co-culture method is labor intensive, requires highly trained personnel, and yields low hESC purity4. Many laboratories have attempted to minimize the number of feeder cells in hESC cultures (i.e. incorporating matrix-coated dishes or other feeder cell types5-8). These modified culture systems have shown some promise, but have not supplanted the standard method for culturing hESCs with mitomycin C-treated mouse embyronic fibroblasts in order to retard unwanted spontaneous differentiation of the hESC cultures. Therefore, the feeder cells used in hESC expansion should be removed during differentiation experiments. Although several techniques are available for purifying the hESC colonies (FACS, MACS, or use of drug resistant vectors) from feeders, these techniques are labor intensive, costly and/or destructive to the hESC. The aim of this project was to invent a method of purification that enables the harvesting of a purer population of hESCs. We have observed that in a confluent hESC culture, the MEF population can be removed using a simple and rapid aspiration of the MEF sheet. This removal is dependent on several factors, including lateral cell-to-cell binding of MEFs that have a lower binding affinity to the styrene culture dish, and the ability of the stem cell colonies to push the fibroblasts outward during the generation of their own "niche". The hESC were then examined for SSEA-4, Oct3/4 and Tra 1-81 expression up to 10 days after MEF removal to ensure maintenance of pluripotency. Moreover, hESC colonies were able to continue growing from into larger formations after MEF removal, providing an additional level of hESC expansion.

Despite ongoing efforts to transition cultures to feeder-free conditions, the derivation and culture of human embryonic stem cells (hESC) remain largely dependent on co-cultures with mouse embryonic feeders (MEFs). Here, we show a novel methodology for rapidly removing feeders from hESC cultures prior to experimentation.

Mouse embryonic fibroblasts (MEFs) were used to establish human embryonic stem cells (hESCs) cultures after blastocyst isolation1. This feeder system ...

Probing High-density Functional Protein Microarrays to Detect Protein-protein Interactions

High-density functional protein microarrays containing ~4,200 recombinant yeast proteins are examined for kinase protein-protein interactions using an affinity purified yeast kinase fusion protein containing a V5-epitope tag for read-out. Purified kinase is obtained through culture of a yeast strain optimized for high copy protein production harboring a plasmid containing a Kinase-V5 fusion construct under a GAL inducible promoter. The yeast is grown in restrictive media with a neutral carbon source for 6 hr followed by induction with 2% galactose. Next, the culture is harvested and kinase is purified using standard affinity chromatographic techniques to obtain a highly purified protein kinase for use in the assay. The purified kinase is diluted with kinase buffer to an appropriate range for the assay and the protein microarrays are blocked prior to hybridization with the protein microarray. After the hybridization, the arrays are probed with monoclonal V5 antibody to identify proteins bound by the kinase-V5 protein. Finally, the arrays are scanned using a standard microarray scanner, and data is extracted for downstream informatics analysis1,2 to determine a high confidence set of protein interactions for downstream validation in vivo.

Using protein microarrays containing nearly the entire S. cerevisiae proteome is probed for rapid unbiased interrogation of thousands of protein-protein interactions in parallel. This method can be utilized for protein-small molecule, posttranslational modification, and other assays in high-throughput.

High-density functional protein microarrays containing ~4,200 recombinant yeast proteins are examined for kinase protein-protein interactions using an ...

Highly Efficient Ligation of Small RNA Molecules for MicroRNA Quantitation by High-Throughput Sequencing

MiRNA cloning and high-throughput sequencing, termed miR-Seq, stands alone as a transcriptome-wide approach to quantify miRNAs with single nucleotide resolution. This technique captures miRNAs by attaching 3&#8217; and 5&#8217; oligonucleotide adapters to miRNA molecules and allows de novo miRNA discovery. Coupling with powerful next-generation sequencing platforms, miR-Seq has been instrumental in the study of miRNA biology. However, significant biases introduced by oligonucleotide ligation steps have prevented miR-Seq from being employed as an accurate quantitation tool. Previous studies demonstrate that biases in current miR-Seq methods often lead to inaccurate miRNA quantification with errors up to 1,000-fold for some miRNAs1,2. To resolve these biases imparted by RNA ligation, we have developed a small RNA ligation method that results in ligation efficiencies of over 95% for both 3&#8217; and 5&#8242; ligation steps. Benchmarking this improved library construction method using equimolar or differentially mixed synthetic miRNAs, consistently yields reads numbers with less than two-fold deviation from the expected value. Furthermore, this high-efficiency miR-Seq method permits accurate genome-wide miRNA profiling from in vivo total RNA samples2.

MicroRNAs (miRNAs) are a widely conserved class of regulatory molecules. Here we describe a miRNA cloning method that relies upon two potent ligation steps followed by high-throughput sequencing. Our method permits accurate genome-wide quantitation of miRNAs.

MiRNA cloning and high-throughput sequencing, termed miR-Seq, stands alone as a transcriptome-wide approach to quantify miRNAs with single nucleotide ...

High-throughput Screening for Chemical Modulators of Post-transcriptionally Regulated Genes

Both transcriptional and post-transcriptional regulation have a profound impact on genes expression. However, commonly adopted cell-based screening assays focus on transcriptional regulation, being essentially aimed at the identification of promoter-targeting molecules. As a result, post-transcriptional mechanisms are largely uncovered by gene expression targeted drug development. Here we describe a cell-based assay aimed at investigating the role of the 3&#39; untranslated region (3&#8217; UTR) in the modulation of the fate of its mRNA, and at identifying compounds able to modify it. The assay is based on the use of a luciferase reporter construct containing the 3&#8217; UTR of a gene of interest stably integrated into a disease-relevant cell line. The protocol is divided into two parts, with the initial focus on the primary screening aimed at the identification of molecules affecting luciferase activity after 24 hr of treatment. The second part of the protocol describes the counter-screening necessary to discriminate compounds modulating luciferase activity specifically through the 3&#8217; UTR. In addition to the detailed protocol and representative results, we provide important considerations about the assay development and the validation of the hit(s) on the endogenous target. The described cell-based reporter gene assay will allow scientists to identify molecules modulating protein levels via post-transcriptional mechanisms dependent on a 3&#8217; UTR.

Here we describe a cell-based reporter gene assay as a valuable tool to screen chemical libraries for compounds modulating post-transcriptional control mechanisms exerted through 3&#8217; UTR.

Both transcriptional and post-transcriptional regulation have a profound impact on genes expression. However, commonly adopted cell-based screening assays ...

Detection of miRNA Targets in High-throughput Using the 3'LIFE Assay

Luminescent Identification of Functional Elements in 3&#8217;UTRs (3&#8217;LIFE) allows the rapid identification of targets of specific miRNAs within an array of hundreds of queried 3&#8217;UTRs. Target identification is based on the dual-luciferase assay, which detects binding at the mRNA level by measuring translational output, giving a functional readout of miRNA targeting. 3&#8217;LIFE uses non-proprietary buffers and reagents, and publically available reporter libraries, making genome-wide screens feasible and cost-effective. 3&#8217;LIFE can be performed either in a standard lab setting or scaled up using liquid handling robots and other high-throughput instrumentation. We illustrate the approach using a dataset of human 3&#8217;UTRs cloned in 96-well plates, and two test miRNAs, let-7c and miR-10b. We demonstrate how to perform DNA preparation, transfection, cell culture and luciferase assays in 96-well format, and provide tools for data analysis. In conclusion 3&#39;LIFE is highly reproducible, rapid, systematic, and identifies high confidence targets.

Detection of miRNA Targets in High-throughput Using the 3&#039;LIFE Assay

Luminescent identification of functional elements in 3&#8217; untranslated regions (3&#8217;UTRs) (3&#8217;LIFE) is a technique to identify functional regulation in 3&#8217;UTRs by miRNAs or other regulatory factors. This protocol utilizes high-throughput methodology such as 96-well transfection and luciferase assays to screen hundreds of putative interactions for functional repression.

Luminescent Identification of Functional Elements in 3&#8217;UTRs (3&#8217;LIFE) allows the rapid identification of targets of specific miRNAs within an ...

Isolation of Mitochondria from Minimal Quantities of Mouse Skeletal Muscle for High Throughput Microplate Respiratory Measurements

Dysfunctional skeletal muscle mitochondria play a role in altered metabolism observed with aging, obesity and Type II diabetes. Mitochondrial respirometric assays from isolated mitochondrial preparations allow for the assessment of mitochondrial function, as well as determination of the mechanism(s) of action of drugs and proteins that modulate metabolism. Current isolation procedures often require large quantities of tissue to yield high quality mitochondria necessary for respirometric assays. The methods presented herein describe how high quality purified mitochondria (~ 450 &#181;g) can be isolated from minimal quantities (~75-100 mg) of mouse skeletal muscle for use in high throughput respiratory measurements. We determined that our isolation method yields 92.5&#177; 2.0% intact mitochondria by measuring citrate synthase activity spectrophotometrically. In addition, Western blot analysis in isolated mitochondria resulted in the faint expression of the cytosolic protein, GAPDH, and the robust expression of the mitochondrial protein, COXIV. The absence of a prominent GAPDH band in the isolated mitochondria is indicative of little contamination from non-mitochondrial sources during the isolation procedure. Most importantly, the measurement of O2 consumption rate with micro-plate based technology and determining the respiratory control ratio (RCR) for coupled respirometric assays shows highly coupled (RCR; &#62;6 for all assays) and functional mitochondria. In conclusion, the addition of a separate mincing step and significantly reducing motor driven homogenization speed of a previously reported method has allowed the isolation of high quality and purified mitochondria from smaller quantities of mouse skeletal muscle that results in highly coupled mitochondria that respire with high function during microplate based respirometirc assays.

Here, we present a modification of a previously reported method that allows for the isolation of high quality and purified mitochondria from smaller quantities of mouse skeletal muscle. This procedure results in highly coupled mitochondria that respire with high function during microplate based respirometirc assays.