Wir danken Craig Paul an der Microarray Core Facility für seine Hilfe. Diese Arbeit wurde vom NIH / NCI gewähren # CA118591 aus dem IMAT Programm unterstützt. SLD erkennt auch der Pennsylvania Raum Stipendium Consortium Fellowship für finanzielle Unterstützung. Diese Veröffentlichung wurde auch von der Pennsylvania State University Materials Research Institute Nano Fabrication Network und der National Science Foundation Cooperative Agreement Nr. 0335765, National Nanotechnology Infrastructure Network, mit der Cornell University unterstützt.

<ol>
	<li>Kulbachinskiy, A. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Methods+for+selection+of+aptamers+to+protein+targets.">Methods for selection of aptamers to protein targets.</a> Biochemistry (Moscow). 72, 1505-1518 (2006).</li><li>Mairal, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Aptamers:+molecular+tools+for+analytical+applications.">Aptamers: molecular tools for analytical applications.</a> Anal Bioanal Chem. 390, 989-1007 (2008).</li><li>Stoltenburg, R., Reinemann, C., Strehlitz, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=SELEX+--+A+(r)evolutionary+method+to+generate+high-affinity+nucleic+acid+ligands.">SELEX -- A (r)evolutionary method to generate high-affinity nucleic acid ligands.</a> Biomolec Engineering. 24, 381-403 (2007).</li><li>Que-Gewirth, N. S., Sullenger, B. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gene+therapy+progress+and+prospects:+RNA+aptamers.">Gene therapy progress and prospects: RNA aptamers.</a> Gene Ther. 14, 283-2891 (2007).</li><li>Cowperthwaite, M. C., Ellington, A. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bioinformatic+analysis+of+the+contribution+of+primer+sequences+to+aptamer+structures.">Bioinformatic analysis of the contribution of primer sequences to aptamer structures.</a> J Mol Evol. 67, 95-102 (2008).</li><li>Shtatland, T., Gill, S. C., Javornik, B. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Interactions+of+Escherichia+coli+RNA+with+bacteriophage+MS2+coat+protein:+genomic+SELEX.">Interactions of Escherichia coli RNA with bacteriophage MS2 coat protein: genomic SELEX.</a> Nucleic Acids Res. 28, E93-E93 (2000).</li><li>Jarosch, F., Buchner, K., Klussmann, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+vitro+selection+using+a+dual+RNA+library+that+allows+primerless+selection.">In vitro selection using a dual RNA library that allows primerless selection.</a> Nucleic Acids Res. 34, E86-E86 (2006).</li><li>Vater, A., Jarosch, F., Buchner, K., Klussmann, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Short+bioactive+Spiegelmers+to+migraine-associated+calcitonin+gene-related+peptide+rapidly+identified+by+a+novel+approach:+tailored-SELEX.">Short bioactive Spiegelmers to migraine-associated calcitonin gene-related peptide rapidly identified by a novel approach: tailored-SELEX.</a> Nucleic Acids Res. 31, E130-E130 (2003).</li><li>Wen, J. D., Gray, D. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Selection+of+genomic+sequences+that+bind+tightly+to+Ff+gene+5+protein:+primer-free+genomic+SELEX.">Selection of genomic sequences that bind tightly to Ff gene 5 protein: primer-free genomic SELEX.</a> Nucleic Acids Res. 32, E182-E182 (2004).</li><li>Musheev, M. U., Krylov, S. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Selection+of+aptamers+by+systematic+evolution+of+ligands+by+exponential+enrichment:+addressing+the+polymerase+chain+reaction+issue.">Selection of aptamers by systematic evolution of ligands by exponential enrichment: addressing the polymerase chain reaction issue.</a> Anal Chim Acta. 564, 91-916 (2006).</li><li>Pan, W. H., Clawson, G. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Primer-free+aptamer+selection+using+a+random+DNA+library.">Primer-free aptamer selection using a random DNA library.</a> Methods Mol Biol. , (2009).</li><li>Pan, W., Xin, P., Clawson, G. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Minimal-Primer+and+Primer-Free+SELEX+Protocols+for+Selection+of+Aptamers+from+Random+DNA+Libraries.">Minimal-Primer and Primer-Free SELEX Protocols for Selection of Aptamers from Random DNA Libraries.</a> BioTechniques. 44, 351-360 (2008).</li><li>Nicewarner-Pena, S., Freeman, G., Reiss, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Submicrometer+metallic+barcodes.">Submicrometer metallic barcodes.</a> Science. 294, 137-141 (2001).</li><li>JC, H. u. l. t. e. e. n., CR, M. a. r. t. i. n. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+general+template-based+method+for+the+preparation+of+nanomaterials.">A general template-based method for the preparation of nanomaterials.</a> J Materials Chem. 7, 1075-1087 (1997).</li></ol>

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		<th>Material Name</th>
		<th>Type</th>
		<th>Company</th>
		<th>Catalogue Number</th>
		<th>Comment</th>
		</tr>
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<tr>
<td>Tris-HCl</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>HotMaster TAQ DNA Polymerase</td>
<td>&nbsp;</td>
<td>5-Prime</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>dNTP Mix</td>
<td>&nbsp;</td>
<td>Sigma</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Acrylamide</td>
<td>&nbsp;</td>
<td>Fisher</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>UltraPure 10X TBE Buffer</td>
<td>&nbsp;</td>
<td>Invitrogen</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Ammonium Persulfate</td>
<td>&nbsp;</td>
<td>Bio-Rad</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>TEMED</td>
<td>&nbsp;</td>
<td>Fisher</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>PhiX174 DNA/Hinf I DNA Marker</td>
<td>&nbsp;</td>
<td>Promega</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Ethidium Bromide</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>&alpha;-32P-dCTP</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Phenol:ChCl3:IAA</td>
<td>&nbsp;</td>
<td>Ambion</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>NaCl</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Ethanol</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Restriction Enzymes</td>
<td>&nbsp;</td>
<td>NEB</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Urea</td>
<td>&nbsp;</td>
<td>Fisher</td>
<td>&nbsp;</td>
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<td>Photographic Film</td>
<td>&nbsp;</td>
<td>ECE Scientific</td>
<td>&nbsp;</td>
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<td>PBS</td>
<td>&nbsp;</td>
<td>Gibco</td>
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<td>CaCl2</td>
<td>&nbsp;</td>
<td>Gibco</td>
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<td>MgCl2</td>
<td>&nbsp;</td>
<td>Gibco</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
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<td>Ni-NTA Agarose Beads</td>
<td>&nbsp;</td>
<td>Qiagen</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Polypropylene Column</td>
<td>&nbsp;</td>
<td>Qiagen</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>NaHPO4</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
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<td>NaAc</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Detroit-551 cells</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>SK-MEL-31 cells</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>MEM</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>TrypLE Express</td>
<td>&nbsp;</td>
<td>Gibco</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>T4 DNA Ligase</td>
<td>&nbsp;</td>
<td>NEB</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Dimethyl Sulfoxide</td>
<td>&nbsp;</td>
<td>Promega</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Sp6 RNA Polymerase</td>
<td>&nbsp;</td>
<td>Promega</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>RNase-Free DNase I</td>
<td>&nbsp;</td>
<td>Promega</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>RNase Inhibitor</td>
<td>&nbsp;</td>
<td>Promega</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>SensiScript Reverse Transcriptase</td>
<td>&nbsp;</td>
<td>Qiagen</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>pCR-2.1-TOPO Vector</td>
<td>&nbsp;</td>
<td>Invitrogen</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>DH5&alpha; Compotent Cells</td>
<td>&nbsp;</td>
<td>Invitrogen</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Plasmid Mini Kit</td>
<td>&nbsp;</td>
<td>Qiagen</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Vector NTI</td>
<td>&nbsp;</td>
<td>Invitrogen</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>T4 Polynucleotide Kinase</td>
<td>&nbsp;</td>
<td>NEB</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>&gamma;-32P-ATP</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>		</tbody>
		</table>
		</div>

primer-free aptamer selection using a random dna library

Aptamere sind hoch strukturierte Oligonukleotiden (DNA oder RNA), die Ziele mit vergleichbaren Affinitäten Antikörper 1 binden kann. Sie sind durch ein in-vitro-Selektion Prozess namens Systematische Evolution von Liganden durch EXponentielle Anreicherung (SELEX) für eine Vielzahl von Zielen zu erkennen, von kleinen Molekülen an Proteine ​​und andere Makromoleküle 2-4 identifiziert. Aptamere haben Eigenschaften, die auch für in vivo diagnostische und / oder therapeutische Anwendungen geeignet sind: Neben einer guten Spezifität und Affinität, sie leicht synthetisiert werden, überleben strengere Verarbeitungsbedingungen, sie sind schwach immunogen und ihrer relativ geringen Größe können in einfache Penetration des Ergebnisses Gewebe. Aptamere, die über die Standard-SELEX-Prozess identifiziert werden üblicherweise ~ 80 Nukleotiden (nt), da sie typischerweise von Nukleinsäure-Bibliotheken mit ~ 40 nt langen randomisierten Regionen plus feste Grundierung Websites von ~ 20 nt auf jeder Seite ausgewählt werden. Die feste Primersequenzen können somit fast umfassen ca. 50% der Bibliothek Sequenzen, und deshalb kann positiv oder negativ beeinträchtigen Identifizierung von Aptameren in der Auswahl 3, obwohl schlagen Bioinformatik Ansätze, die den festen Sequenzen nicht wesentlich dazu beitragen, Aptamer-Struktur nach Auswahl 5 . Um diese möglichen Probleme haben Primersequenzen von komplementären Oligonukleotiden blockiert oder ausgeschaltet, um unterschiedliche Sequenzen auf halbem Weg in die Runde der SELEX 6, oder sie haben auf 6-9 nt 7, 8 getrimmt. Wen und Gray 9 ausgebildet einem Primer-freie genomische SELEX-Verfahren, in denen die Primersequenzen waren völlig aus der Bibliothek vor der Auswahl entfernt und wurden dann regeneriert werden, um Verstärkung des ausgewählten genomischen Fragmenten zu ermöglichen. Doch die Technik zu beschäftigen, hat eine einzigartige Genbank konstruiert werden, bei dem sich nur die Vielfalt und die Regeneration nach dem Runden der Selektion beruht auf einer linearen Reamplifikation Schritt. Alternativ sind auch Bemühungen um die Probleme, die durch feste Primersequenzen mit hohem Wirkungsgrad Partitionierung verursacht umgehen mit Problemen in Bezug auf die PCR-Amplifikation 10 erfüllt. Wir haben ein Primer-free (PF) Auswahl-Verfahren deutlich vereinfacht SELEX Verfahren und beseitigt effektiv Primer-Störungsprobleme 11, 12 entwickelt. Die Protokolle der Arbeit in einer einfachen Weise. Die zentrale random Region der Bibliothek ist ohne fremde flankierenden Sequenzen gereinigt und ist ein geeignetes Ziel (zum Beispiel, um ein gereinigtes Protein oder komplexen Gemischen wie Zell-Linien) gebunden. Dann werden die gebundenen Sequenzen erhalten werden, wieder mit flankierenden Sequenzen, und wieder verstärkt auf ausgewählte Sub-Bibliotheken zu generieren. Als ein Beispiel, hier sind wir selektierten Aptamere zu S100B, ein Protein Marker für Melanome. Binding Assays zeigte Kd s in den 10 -7 - 10 -8 M Reihe nach ein paar Runden der Selektion, und wir zeigen, dass die Aptamere effektiv funktionieren in einer Sandwich-Bindung Format.

Watch this Scientific Journal Video about Primer-Free Aptamer Selection Using A Random DNA Library at JoVE.com

Primer-Free Aptamer Selection Using A Random DNA Library

SELEX-Protokolle umfassen mehrere Runden der Selektion, von denen jeder Regeneration von Liganden, die wiederum erfordern feste Primersequenzen flankierenden die zufällige Bibliothek Regionen erfordern. Diese festen Primersequenzen können mit der Auswahl (false positive und negative) stören. Hier präsentieren wir eine Grundierung-free-Protokoll.

Primer-Free Aptamer Selection mit einem zufälligen DNA-Bibliothek

Aptamers are highly structured oligonucleotides (DNA or RNA) that can bind to targets with affinities comparable to antibodies 1. They are identified ...

primer-free-aptamer-selection-using-a-random-dna-library

Research

JoVE Journal

Biology

24.6K Aufrufe.  Pennsylvania State University. SELEX-Protokolle umfassen mehrere Runden der Selektion, von denen jeder Regeneration von Liganden, die wiederum erfordern feste Primersequenzen flankierenden die zufällige Bibliothek Regionen erfordern. Diese festen Primersequenzen können mit der Auswahl (false positive und negative) stören. Hier präsentieren wir eine Grundierung-free-Protokoll.

Serie: Primer-Free Aptamer Selection Using A Random DNA Library

Direct Observation of Enzymes Replicating DNA Using a Single-molecule DNA Stretching Assay

We describe a method for observing real time replication of individual DNA molecules mediated by proteins of the bacteriophage replication system. Linearized &lambda; DNA is modified to have a biotin on the end of one strand, and a digoxigenin moiety on the other end of the same strand. The biotinylated end is attached to a functionalized glass coverslip and the digoxigeninated end to a small bead. The assembly of these DNA-bead tethers on the surface of a flow cell allows a laminar flow to be applied to exert a drag force on the bead. As a result, the DNA is stretched close to and parallel to the surface of the coverslip at a force that is determined by the flow rate (Figure 1). The length of the DNA is measured by monitoring the position of the bead. Length differences between single- and double-stranded DNA are utilized to obtain real-time information on the activity of the replication proteins at the fork. Measuring the position of the bead allows precise determination of the rates and processivities of DNA unwinding and polymerization (Figure 2).

We describe a method for observing real time replication of individual DNA molecules mediated by proteins of the bacteriophage replication system.

Direkte Beobachtung von Enzymen Replizieren DNA Mit einem Single-Molekül DNA Stretching Assay

We describe a method for observing real time replication of individual DNA molecules mediated by proteins of the bacteriophage replication system. ...

Forschung

Biologie

DNA Stable-Isotope Probing (DNA-SIP)

DNA stable-isotope probing (DNA-SIP) is a powerful technique for identifying active microorganisms that assimilate particular carbon substrates and nutrients into cellular biomass. As such, this cultivation-independent technique has been an important methodology for assigning metabolic function to the diverse communities inhabiting a wide range of terrestrial and aquatic environments. Following the incubation of an environmental sample with stable-isotope labelled compounds, extracted nucleic acid is subjected to density gradient ultracentrifugation and subsequent gradient fractionation to separate nucleic acids of differing densities. Purification of DNA from cesium chloride retrieves labelled and unlabelled DNA for subsequent molecular characterization (e.g. fingerprinting, microarrays, clone libraries, metagenomics). This JoVE video protocol provides visual step-by-step explanations of the protocol for density gradient ultracentrifugation, gradient fractionation and recovery of labelled DNA. The protocol also includes sample SIP data and highlights important tips and cautions that must be considered to ensure a successful DNA-SIP analysis.

DNA Stable-Isotope Probing DNA-SIP

DNA stable-isotope probing is a cultivation-independent method to identify and characterize active communities of microorganisms that are capable of utilizing specific substrates. Assimilation of substrate enriched in heavy isotope leads to incorporation of labelled atoms into microbial biomass. Density gradient ultracentrifugation retrieves labelled DNA for downstream molecular analyses.

DNA stable-isotope probing (DNA-SIP) is a powerful technique for identifying active microorganisms that assimilate particular carbon substrates and ...

Single Particle Electron Microscopy Reconstruction of the Exosome Complex Using the Random Conical Tilt Method

Single particle electron microscopy (EM) reconstruction has recently become a popular tool to get the three-dimensional (3D) structure of large macromolecular complexes. Compared to X-ray crystallography, it has some unique advantages. First, single particle EM reconstruction does not need to crystallize the protein sample, which is the bottleneck in X-ray crystallography, especially for large macromolecular complexes. Secondly, it does not need large amounts of protein samples. Compared with milligrams of proteins necessary for crystallization, single particle EM reconstruction only needs several micro-liters of protein solution at nano-molar concentrations, using the negative staining EM method. However, despite a few macromolecular assemblies with high symmetry, single particle EM is limited at relatively low resolution (lower than 1 nm resolution) for many specimens especially those without symmetry. This technique is also limited by the size of the molecules under study, i.e. 100 kDa for negatively stained specimens and 300 kDa for frozen-hydrated specimens in general.
For a new sample of unknown structure, we generally use a heavy metal solution to embed the molecules by negative staining. The specimen is then examined in a transmission electron microscope to take two-dimensional (2D) micrographs of the molecules. Ideally, the protein molecules have a homogeneous 3D structure but exhibit different orientations in the micrographs. These micrographs are digitized and processed in computers as "single particles". Using two-dimensional alignment and classification techniques, homogenous molecules in the same views are clustered into classes. Their averages enhance the signal of the molecule's 2D shapes. After we assign the particles with the proper relative orientation (Euler angles), we will be able to reconstruct the 2D particle images into a 3D virtual volume.
In single particle 3D reconstruction, an essential step is to correctly assign the proper orientation of each single particle. There are several methods to assign the view for each particle, including the angular reconstitution1 and random conical tilt (RCT) method2. In this protocol, we describe our practice in getting the 3D reconstruction of yeast exosome complex using negative staining EM and RCT. It should be noted that our protocol of electron microscopy and image processing follows the basic principle of RCT but is not the only way to perform the method. We first describe how to embed the protein sample into a layer of Uranyl-Formate with a thickness comparable to the protein size, using a holey carbon grid covered with a layer of continuous thin carbon film. Then the specimen is inserted into a transmission electron microscope to collect untilted (0-degree) and tilted (55-degree) pairs of micrographs that will be used later for processing and obtaining an initial 3D model of the yeast exosome. To this end, we perform RCT and then refine the initial 3D model by using the projection matching refinement method3.

This article describes a standard method to get a three-dimensional (3D) reconstruction of biological macromolecules using negative staining electron microscopy (EM). In this protocol, we explain how to get the 3D structure of the Saccharomyces cerevisiae exosome complex at medium resolution using the random conical tilt reconstruction method (RCT).

Single Particle Electron Microscopy Rekonstruktion der Exosom Complex Mit der Random-konische Tilt-Methode

Single particle electron microscopy (EM) reconstruction has recently become a popular tool to get the three-dimensional (3D) structure of large ...

Genome-wide Screen for miRNA Targets Using the MISSION Target ID Library

The Target ID Library is designed to assist in discovery and identification of microRNA (miRNA) targets. The Target ID Library is a plasmid-based, genome-wide cDNA library cloned into the 3'UTR downstream from the dual-selection fusion protein, thymidine kinase-zeocin (TKzeo). The first round of selection is for stable transformants, followed with introduction of a miRNA of interest, and finally, selecting for cDNAs containing the miRNA's target. Selected cDNAs are identified by sequencing (see Figure 1-3 for Target ID Library Workflow and details).
To ensure broad coverage of the human transcriptome, Target ID Library cDNAs were generated via oligo-dT priming using a pool of total RNA prepared from multiple human tissues and cell lines. Resulting cDNA range from 0.5 to 4 kb, with an average size of 1.2 kb, and were cloned into the p3&#900;TKzeo dual-selection plasmid (see Figure 4 for plasmid map). The gene targets represented in the library can be found on the Sigma-Aldrich webpage. Results from Illumina sequencing (Table 3), show that the library includes 16,922 of the 21,518 unique genes in UCSC RefGene (79%), or 14,000 genes with 10 or more reads (66%).

The Target ID Library is a plasmid-based, genome-wide collection of cloned cDNA used to identify miRNA targets. Here we demonstrate its use and application.

Genomweiten Screen für miRNA-Targets mit dem Missionsziel ID-Bibliothek

The Target ID Library is designed to assist in discovery and identification of microRNA (miRNA) targets. The Target ID Library is a plasmid-based, ...

Quantitative Analysis of Random Migration of Cells Using Time-lapse Video Microscopy

Cell migration is a dynamic process, which is important for embryonic development, tissue repair, immune system function, and tumor invasion 1, 2. During directional migration, cells move rapidly in response to an extracellular chemotactic signal, or in response to intrinsic cues 3 provided by the basic motility machinery. Random migration occurs when a cell possesses low intrinsic directionality, allowing the cells to explore their local environment.
Cell migration is a complex process, in the initial response cell undergoes polarization and extends protrusions in the direction of migration 2. Traditional methods to measure migration such as the Boyden chamber migration assay is an easy method to measure chemotaxis in vitro, which allows measuring migration as an end point result. However, this approach neither allows measurement of individual migration parameters, nor does it allow to visualization of morphological changes that cell undergoes during migration.
Here, we present a method that allows us to monitor migrating cells in real time using video - time lapse microscopy. Since cell migration and invasion are hallmarks of cancer, this method will be applicable in studying cancer cell migration and invasion in vitro. Random migration of platelets has been considered as one of the parameters of platelet function 4, hence this method could also be helpful in studying platelet functions. This assay has the advantage of being rapid, reliable, reproducible, and does not require optimization of cell numbers. In order to maintain physiologically suitable conditions for cells, the microscope is equipped with CO2 supply and temperature thermostat. Cell movement is monitored by taking pictures using a camera fitted to the microscope at regular intervals. Cell migration can be calculated by measuring average speed and average displacement, which is calculated by Slidebook software.

This method allows monitoring of cells in real time and quantitative measurements of different cell migration parameters such as speed, displacement, and velocity. Unlike the traditional methods, this real time approach is not based on endpoint quantitative migration measurements; instead it allows monitoring and calculating different parameters continuously.

Quantitative Analyse der ungerichtete Migration von Zellen unter Verwendung Zeitraffer-Video-Mikroskopie

Cell migration is a dynamic process, which is important for embryonic development, tissue repair, immune system function, and tumor invasion 1, 2. During ...

Improving the Success Rate of Protein Crystallization by Random Microseed Matrix Screening

Random microseed matrix screening (rMMS) is a protein crystallization technique in which seed crystals are added to random screens. By increasing the likelihood that crystals will grow in the metastable zone of a protein's phase diagram, extra crystallization leads are often obtained, the quality of crystals produced may be increased, and a good supply of crystals for data collection and soaking experiments is provided. Here we describe a general method for rMMS that may be applied to either sitting drop or hanging drop vapor diffusion experiments, established either by hand or using liquid handling robotics, in 96-well or 24-well tray format.

Here we describe a general method for random microseed matrix screening. This technique is shown to significantly increase the success rate of protein crystallization screening experiments, reduce the need for optimization, and provide a reliable supply of crystals for data collection and ligand-soaking experiments.

Verbesserung der Erfolgsrate der Proteinkristallisation nach Zufall Microseed Matrix Screening

Random microseed matrix screening  (rMMS) is a protein crystallization technique in which seed crystals are added  to random screens. By increasing the ...

A Protocol for Phage Display and Affinity Selection Using Recombinant Protein Baits

Using recombinant phage as a scaffold to present various protein portions encoded by a directionally cloned cDNA library to immobilized bait molecules is an efficient means to discover interactions. The technique has largely been used to discover protein-protein interactions but the bait molecule to be challenged need not be restricted to proteins. The protocol presented here has been optimized to allow a modest number of baits to be screened in replicates to maximize the identification of independent clones presenting the same protein. This permits greater confidence that interacting proteins identified are legitimate interactors of the bait molecule. Monitoring the phage titer after each affinity selection round provides information on how the affinity selection is progressing as well as on the efficacy of negative controls. One means of titering the phage, and how and what to prepare in advance to allow this process to progress as efficiently as possible, is presented. Attributes of amplicons retrieved following isolation of independent plaque are highlighted that can be used to ascertain how well the affinity selection has progressed. Trouble shooting techniques to minimize false positives or to bypass persistently recovered phage are explained. Means of reducing viral contamination flare up are discussed.

Phage display is a powerful technique to capture proteins or protein moieties that interact with an immobilized molecule of interest. Once a decision of the type of phage cDNA library to create and screen has been made, the protocol described here permits efficient affinity selection leading to identification of interactors.

Ein Protokoll für die Phagen-Display-und Affinity Auswahl mit rekombinantem Protein-Köder

Using  recombinant phage as a scaffold to present various protein portions encoded by  a directionally cloned cDNA library to immobilized bait molecules ...

Real-time Imaging of Single Engineered RNA Transcripts in Living Cells Using Ratiometric Bimolecular Beacons

The growing realization that both the temporal and spatial regulation of gene expression can have important consequences on cell function has led to the development of diverse techniques to visualize individual RNA transcripts in single living cells. One promising technique that has recently been described utilizes an oligonucleotide-based optical probe, ratiometric bimolecular beacon (RBMB), to detect RNA transcripts that were engineered to contain at least four tandem repeats of the RBMB target sequence in the 3&#8217;-untranslated region. RBMBs are specifically designed to emit a bright fluorescent signal upon hybridization to complementary RNA, but otherwise remain quenched. The use of a synthetic probe in this approach allows photostable, red-shifted, and highly emissive organic dyes to be used for imaging. Binding of multiple RBMBs to the engineered RNA transcripts results in discrete fluorescence spots when viewed under a wide-field fluorescent microscope. Consequently, the movement of individual RNA transcripts can be readily visualized in real-time by taking a time series of fluorescent images. Here we describe the preparation and purification of RBMBs, delivery into cells by microporation and live-cell imaging of single RNA transcripts.

Ratiometric bimolecular beacons (RBMBs) can be used to image single engineered RNA transcripts in living cells. Here, we describe the preparation and purification of RBMBs, delivery of RBMBs into cells by microporation and fluorescent imaging of single RNA transcripts in real-time.

Echtzeit-Bildgebung von Einzel Engineered RNA-Transkripte in lebenden Zellen Mit Ratiometrische Bimolekulare Beacons

The growing realization that both the temporal and spatial regulation of gene expression can have important consequences on cell function has led to the ...

Reduced-gravity Environment Hardware Demonstrations of a Prototype Miniaturized Flow Cytometer and Companion Microfluidic Mixing Technology

Until recently, astronaut blood samples were collected in-flight, transported to earth on the Space Shuttle, and analyzed in terrestrial laboratories. If humans are to travel beyond low Earth orbit, a transition towards space-ready, point-of-care (POC) testing is required. Such testing needs to be comprehensive, easy to perform in a reduced-gravity environment, and unaffected by the stresses of launch and spaceflight. Countless POC devices have been developed to mimic laboratory scale counterparts, but most have narrow applications and few have demonstrable use in an in-flight, reduced-gravity environment. In fact, demonstrations of biomedical diagnostics in reduced gravity are limited altogether, making component choice and certain logistical challenges difficult to approach when seeking to test new technology. To help fill the void, we are presenting a modular method for the construction and operation of a prototype blood diagnostic device and its associated parabolic flight test rig that meet the standards for flight-testing onboard a parabolic flight, reduced-gravity aircraft. The method first focuses on rig assembly for in-flight, reduced-gravity testing of a flow cytometer and a companion microfluidic mixing chip. Components are adaptable to other designs and some custom components, such as a microvolume sample loader and the micromixer may be of particular interest. The method then shifts focus to flight preparation, by offering guidelines and suggestions to prepare for a successful flight test with regard to user training, development of a standard operating procedure (SOP), and other issues. Finally, in-flight experimental procedures specific to our demonstrations are described.

Spaceflight blood diagnostics need innovation. Few demonstrations have been published illustrating in-flight, reduced-gravity health diagnostic technology. Here we present a method for construction and operation of a parabolic flight test rig for a prototype point-of-care flow-cytometry design, with components and preparation strategies adaptable to other setups.

Reduzierte Gravitationsbereich Hardware Demonstrationen eines Prototyps Miniaturisierte Durchflusszytometer und Companion Microfluidic Mischtechnik

Until recently, astronaut blood samples were collected in-flight, transported to earth on the Space Shuttle, and analyzed in terrestrial laboratories. If ...

Amplification, Next-generation Sequencing, and Genomic DNA Mapping of Retroviral Integration Sites

Retroviruses exhibit signature integration preferences on both the local and global scales. Here, we present a detailed protocol for (1) generation of diverse libraries of retroviral integration sites using ligation-mediated PCR (LM-PCR) amplification and next-generation sequencing (NGS), (2) mapping the genomic location of each virus-host junction using BEDTools, and (3) analyzing the data for statistical relevance. Genomic DNA extracted from infected cells is fragmented by digestion with restriction enzymes or by sonication. After suitable DNA end-repair, double-stranded linkers are ligated onto the DNA ends, and semi-nested PCR is conducted using primers complementary to both the long terminal repeat (LTR) end of the virus and the ligated linker DNA. The PCR primers carry sequences required for DNA clustering during NGS, negating the requirement for separate adapter ligation. Quality control (QC) is conducted to assess DNA fragment size distribution and adapter DNA incorporation prior to NGS. Sequence output files are filtered for LTR-containing reads, and the sequences defining the LTR and the linker are cropped away. Trimmed host cell sequences are mapped to a reference genome using BLAT and are filtered for minimally 97% identity to a unique point in the reference genome. Unique integration sites are scrutinized for adjacent nucleotide (nt) sequence and distribution relative to various genomic features. Using this protocol, integration site libraries of high complexity can be constructed from genomic DNA in three days. The entire protocol that encompasses exogenous viral infection of susceptible tissue culture cells to integration site analysis can therefore be conducted in approximately one to two weeks. Recent applications of this technology pertain to longitudinal analysis of integration sites from HIV-infected patients.

We describe a protocol for amplifying retroviral integration sites from the genomic DNA of infected cells, sequencing the amplified virus-host junctions, and then mapping these sequences to a reference genome. We also describe techniques to quantify the distribution of integration sites relative to various genomic annotations using BEDTools.

Amplification, Next-Generation-Sequenzierung und genomischer DNA Mapping von Retrovirale Integration Seiten

Retroviruses exhibit signature integration preferences on both the local and global scales. Here, we present a detailed protocol for (1) generation of ...