La recherche dans le laboratoire Sokol est parrainé par le Institues national de la santé.

1. Fécondation in vitro de Xenopus Oeufs <ol><li> Obtenir œufs de grenouilles femelles qui ont été injectés avec la gonadotrophine chorionique humaine (400 unités / grenouille) 12 heures avant l&#39;expérience. </li><li> Placez les oeufs dans une petite quantité (0,5-1 ml) de solution à 1 x Marc Ringer modifiée (ROR) 10 à les œufs et les féconder in vitro avec un petit morceau de testicule disséqués. Après 2-3 minutes, ajouter 0,1 x ROR pour couvrir toute la surface des œufs. En 20 minutes, l&#39;oeuf gelée de poil est enlevé par la cystéine 3% - HCL (ajusté à pH 8 avec de l&#39;hydroxyde de sodium). Les œufs sont lavés avec 0,1 x ROR à trois reprises et laissé dans un incubateur à froid (13 ° C) pour les injections. </li><li> Les oeufs fécondés sont autorisés à se développer pour stades 2-4 cellules. Pour les injections, les embryons sont transférés dans la solution contenant 3% de Ficoll, 0,5 x ROR. </li></ol> 2. Microinjection d&#39;ARN <ol><li> ARN sont synthétisés à partir de matrices d&#39;ADN linéarisé en utilisant mMessage mMachine kit (Ambion) et dilué avec de l&#39;eau exempte de RNase à la concentration des stocks de 0,1-1 pg / pl. Les doses optimales de l&#39;ARN pour les injections sont déterminées dans des expériences pilotes. ARN pour Diversin-DP, le marqueur membranaire GFP-CAAX et Frizzled 8 sont utilisées à 0,1-1 ng par injection. </li><li> Les aiguilles ne sont préparés avec un extracteur d&#39;aiguilles à partir d&#39;un capillaire et puis avec un moulin à aiguille. Avant l&#39;injection, chaque aiguille est calibré avec de l&#39;eau pour éjecter 10 nl d&#39;injection de liquide par. </li><li> Pour les injections, les embryons sont placés sur un plat en plastique dans une gouttelette grand Ficoll 3%, 0,5 x ROR. Un microlitre de solution d&#39;ARN est aspiré dans une aiguille d&#39;injection avec Narishige microinjecteur. 10 nl d&#39;ARN est injecté dans des animaux de 8 blastomères d&#39;embryons de cellules 2-3 fois. Les embryons injectés sont transférés dans un puits de la plaque de 12 puits. </li></ol> 3. Préparation des explants ectodermiques <ol><li> Lorsque les embryons injectés rejoindre début stade gastrula, ils sont transférés dans 0,6 x ROR solution dans un plat de 3 cm recouvert de plastique avec 1% d&#39;agarose. Membrane vitelline est enlevée manuellement avec une paire de pinces. Explants ectodermiques sont excisés du embryons en utilisant une aiguille de tungstène et une hairloop. </li><li> Explants ectodermiques sont transférés dans un flacon en verre et fixé au formol à 3,7% en tampon phosphate salin (PBS) pendant 30 minutes. Explants fixes sont lavées avec du PBS à trois reprises (10 minutes chacun). DAPI est inclus dans le troisième lavage à tacher les noyaux. </li><li> Les explants sont montés sur une lame de verre. Deux bandes de scotch sont attachés à la diapositive et les explants sont placés entre les deux bandes. Depuis la surface extérieure des explants est pigmentée, le côté intérieur de la explants doivent faire face à l&#39;objectif du microscope. Ajouter deux à trois gouttes de 20 pl de la solution de montage (70% de glycérol dans du PBS, dont 25 mg / ml DABCO, anti-décoloration réactif) 11. Mettre une lamelle sur le dessus. </li></ol> 4. Imagerie des explants Sous un microscope à fluorescence <ol><li> Les échantillons sont considérés sous microscope à fluorescence Zeiss Axioplan avec des filtres appropriés. </li><li> Les images sont prises avec l&#39;attachement Apotome de visualiser un plan spécifique de plusieurs explants indépendants. </li></ol> 5. Cryosectioning Cryosectioning est une autre façon de visualiser la distribution des protéines fluorescentes dans la cellule et plus applicable pour immunocoloration. Au stade 10, les embryons sont fixes pendant 1-2 heures avec fixateur de Dent (20% de DMSO, 80% de méthanol), lavées avec du PBS, et intégrés dans une solution de sucrose 15% des poissons gelatin/15 11%. Les embryons sont congelés rapidement embarqué sur la glace sèche et cryocoupes sont générés sur Leica cryostat. Sections de la Croix comprendrait cellules ectodermiques qui héritent des ARN injectés et leurs produits protéiques traduites. Les sections de conserver la fluorescence et peuvent être immunocolorés avec des anticorps spécifiques et étiquetés avec des anticorps secondaires conjugués avec la fluorescence. Les noyaux sont colorés au DAPI. Les milieux de montage sont les mêmes que décrit ci-dessus. L&#39;imagerie peut être réalisée comme décrit ci-dessus. 6. Les résultats représentatifs: <img src="/files/ftp_upload/2700/2700fig1.jpg" alt="Figure 1" /> Figure 1. Récepteurs Frizzled recrues Diversin à la membrane cellulaire. Ectoderme cellules exprimant 8 Frizzled (Xfz8) et Div-DP ARN révèle Div-DP à la membrane cellulaire, au lieu du centrosome (tel que révélé par g-tubuline de co-marquage). Le schéma de l&#39;expérience est au sommet, une coupe transversale typique est montré.

<ol>
	<li>Gurdon, J. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Embryonic+induction+---+molecular+aspects.">Embryonic induction --- molecular aspects.</a> Development. 99, 285-306 (1987).</li><li>Moody, S. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Principles of Developmental Genetics. , (2007).</li><li>Clevers, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Wnt/beta-catenin+signaling+in+development+and+disease.">Wnt/beta-catenin signaling in development and disease.</a> Cell. 127, 469-480 (2006).</li><li>Klaus, A., Birchmeier, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Wnt+signalling+and+its+impact+on+development+and+cancer.">Wnt signalling and its impact on development and cancer.</a> Nat Rev Cancer. 8, 387-398 (2008).</li><li>Gordon, M. D., Nusse, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Wnt+signaling:+multiple+pathways,+multiple+receptors,+and+multiple+transcription+factors.">Wnt signaling: multiple pathways, multiple receptors, and multiple transcription factors.</a> J Biol Chem. 281, 22429-22433 (2006).</li><li>Schwarz-Romond, T., Asbrand, C., Bakkers, J., Kuhl, M., Schaeffer, H. J., Huelsken, J., Behrens, J., Hammerschmidt, M., Birchmeier, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+ankyrin+repeat+protein+Diversin+recruits+Casein+kinase+Iepsilon+to+the+beta-catenin+degradation+complex+and+acts+in+both+canonical+Wnt+and+Wnt/JNK+signaling.">The ankyrin repeat protein Diversin recruits Casein kinase Iepsilon to the beta-catenin degradation complex and acts in both canonical Wnt and Wnt/JNK signaling.</a> Genes Dev. 16, 2073-2084 (2002).</li><li>Moeller, H., Jenny, A., Schaeffer, H. J., Schwarz-Romond, T., Mlodzik, M., Hammerschmidt, M., Birchmeier, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Diversin+regulates+heart+formation+and+gastrulation+movements+in+development.">Diversin regulates heart formation and gastrulation movements in development.</a> Proc Natl Acad Sci U S A. 103, 15900-15905 (2006).</li><li>Itoh, K., Jenny, A., Mlodzik, M., Sokol, S. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Centrosomal+localization+of+Diversin+and+its+relevance+to+Wnt+signaling.">Centrosomal localization of Diversin and its relevance to Wnt signaling.</a> J. Cell Sci. 122, 3791-3798 (2009).</li><li>Itoh, K., Jacob, J., Sokol, Y. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+role+for+Xenopus+Frizzled+8+in+dorsal+development.">A role for Xenopus Frizzled 8 in dorsal development.</a> Mech Dev. 74, 145-157 (1998).</li><li>Newport, J., Kirschner, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+major+developmental+transition+in+early+Xenopus+embryos:+I.+characterization+and+timing+of+cellular+changes+at+the+midblastula+stage.">A major developmental transition in early Xenopus embryos: I. characterization and timing of cellular changes at the midblastula stage.</a> Cell. 30, 675-686 (1982).</li><li>Itoh, K., Brott, B. K., Bae, G. U., Ratcliffe, M. J., Sokol, S. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nuclear+localization+is+required+for+Dishevelled+function+in+Wnt/beta-catenin+signaling.">Nuclear localization is required for Dishevelled function in Wnt/beta-catenin signaling.</a> J Biol. 4, 3-3 (2005).</li></ol>

Nous avons utilisé le protocole ci-dessus pour caractériser la localisation subcellulaire des Diversin. Dans des explants pôle animal, Diversin-DP a été détecté à côté du noyau et colocalisés avec g-tubuline, un marqueur centrosomale, dans cryocoupes (figure 1). Une fois la localisation subcellulaire d&#39;une protéine est identifiée, les constructions de suppression peuvent être générés pour établir quels domaines protéiques sont nécessaires et suffisants pour la localisation subcellulaire. En utili...

polarized translocation of fluorescent proteins in xenopus ectoderm in response to wnt signaling

Polarité cellulaire est une propriété fondamentale des cellules eucaryotes qui est dynamiquement régulée par des facteurs intrinsèques et extrinsèques au cours développement embryonnaire 1, 2. Une des voies de signalisation impliquées dans cette régulation est la voie Wnt, qui est utilisé à plusieurs reprises durant l&#39;embryogenèse et critique pour la maladie de l&#39;homme 3, 4, 5. De multiples composants moléculaires de cette voie de signalisation coordonnée réguler de manière spatialement limité, mais les mécanismes sous-jacents ne sont pas pleinement compris. Xenopus cellules embryonnaires épithéliales est un excellent système pour étudier la localisation subcellulaire des protéines de signalisation différents. Protéines de fusion fluorescentes sont exprimés dans les embryons de Xenopus par microinjection d&#39;ARN, des explants ectodermiques sont préparés et la localisation des protéines est évaluée par épifluorescence. Dans ce protocole expérimental, nous décrivons comment la localisation subcellulaire des Diversin, une protéine cytoplasmique qui a été impliquée dans la signalisation et la détermination de la polarité cellulaire 6, 7 est visualisée dans les cellules ectodermiques Xénope pour étudier la transduction du signal Wnt 8. Coexpression d&#39;un ligand Wnt ou d&#39;un récepteur Frizzled modifie la répartition des Diversin fusionné avec la protéine fluorescente rouge, DP, et il recrute à la membrane cellulaire de façon polarisée 8, 9. Ce protocole ex vivo devrait être un complément utile aux études in vitro des cellules mammaliennes cultivées, dans laquelle le contrôle spatial de la signalisation est différente de celle du tissu intact et est beaucoup plus difficile à analyser.

Watch this Scientific Journal Video about Polarized Translocation of Fluorescent Proteins in Xenopus Ectoderm in Response to Wnt Signaling at JoVE.com

Polarized Translocation of Fluorescent Proteins in Xenopus Ectoderm in Response to Wnt Signaling

Xenopus embryonnaire ectoderme est devenu un modèle attractif pour les études de la polarité cellulaire. Un essai est décrit, dans lequel la distribution subcellulaire des protéines fluorescentes dans les cellules est évaluée ectoderme. Ce protocole aidera aborder les questions relatives au contrôle spatial de la signalisation.

Translocation polarisée des protéines fluorescentes dans les Xenopus</emEctoderme> en réponse à la signalisation Wnt

Cell polarity is a fundamental property of eukaryotic cells that is dynamically regulated by both intrinsic and extrinsic factors during embryonic ...

polarized-translocation-fluorescent-proteins-xenopus-ectoderm

Research

JoVE Journal

Biology

Polarized Translocation of Fluorescent Proteins in Xenopus Ectoderm in Response to Wnt Signaling

10.7K vues.  Mount Sinai School of Medicine. Xenopus embryonnaire ectoderme est devenu un modèle attractif pour les études de la polarité cellulaire. Un essai est décrit, dans lequel la distribution subcellulaire des protéines fluorescentes dans les cellules est évaluée ectoderme. Ce protocole aidera aborder les questions relatives au contrôle spatial de la signalisation.

Vidéo: Polarized Translocation of Fluorescent Proteins in Xenopus Ectoderm in Response to Wnt Signaling

Quantification of &gamma;H2AX Foci in Response to Ionising Radiation

DNA double-strand breaks (DSBs), which are induced by either endogenous metabolic processes or by exogenous sources, are one of the most critical DNA lesions with respect to survival and preservation of genomic integrity. An early response to the induction of DSBs is phosphorylation of the H2A histone variant, H2AX, at the serine-139 residue, in the highly conserved C-terminal SQEY motif, forming &gamma;H2AX1. Following induction of DSBs, H2AX is rapidly phosphorylated by the phosphatidyl-inosito 3-kinase (PIKK) family of proteins, ataxia telangiectasia mutated (ATM), DNA-protein kinase catalytic subunit and ATM and RAD3-related (ATR)2. Typically, only a few base-pairs (bp) are implicated in a DSB, however, there is significant signal amplification, given the importance of chromatin modifications in DNA damage signalling and repair. Phosphorylation of H2AX mediated predominantly by ATM spreads to adjacent areas of chromatin, affecting approximately 0.03% of total cellular H2AX per DSB2,3. This corresponds to phosphorylation of approximately 2000 H2AX molecules spanning ~2 Mbp regions of chromatin surrounding the site of the DSB and results in the formation of discrete &gamma;H2AX foci which can be easily visualized and quantitated by immunofluorescence microscopy2. The loss of &gamma;H2AX at DSB reflects repair, however, there is some controversy as to what defines complete repair of DSBs; it has been proposed that rejoining of both strands of DNA is adequate however, it has also been suggested that re-instatement of the original chromatin state of compaction is necessary4-8. The disappearence of &gamma;H2AX involves at least in part, dephosphorylation by phosphatases, phosphatase 2A and phosphatase 4C5,6. Further, removal of &gamma;H2AX by redistribution involving histone exchange with H2A.Z has been implicated7,8. Importantly, the quantitative analysis of &gamma;H2AX foci has led to a wide range of applications in medical and nuclear research. Here, we demonstrate the most commonly used immunofluorescence method for evaluation of initial DNA damage by detection and quantitation of &gamma;H2AX foci in &gamma;-irradiated adherent human keratinocytes9.

Quantification of &amp;#947;H2AX Foci in Response to Ionising Radiation

Quantification of DNA double-strand streaks using &gamma;H2AX formation as a molecular marker has become an invaluable tool in radiation biology. Here we demonstrate the use of an immunofluorescence assay for quantification of &gamma;H2AX foci after exposure of cells to radiation.

Quantification des γH2AX Foci en réponse aux radiations ionisantes

DNA double-strand breaks (DSBs), which are induced by either endogenous metabolic processes or by exogenous sources, are one of the most critical DNA ...

Recherche

Biologie

Photoconversion of Purified Fluorescent Proteins and Dual-probe Optical Highlighting in Live Cells

Photoconvertible fluorescent proteins (pc-FPs) are a class of fluorescent proteins with "optical highlighter" capability, meaning that the color of fluorescence can be changed by exposure to light of a specific wavelength. Optical highlighting allows noninvasive marking of a subpopulation of fluorescent molecules, and is therefore ideal for tracking single cells or organelles.
Critical parameters for efficient photoconversion are the intensity and the exposure time of the photoconversion light. If the intensity is too low, photoconversion will be slow or not occur at all. On the other hand, too much intensity or too long exposure can photobleach the protein and thereby reduce the efficiency of photoconversion.
This protocol describes a general approach how to set up a confocal laser scanning microscope for pc-FP photoconversion applications. First, we describe a procedure for preparing purified protein droplet samples. This sample format is very convenient for studying the photophysical behavior of fluorescent proteins under the microscope. Second, we will use the protein droplet sample to show how to configure the microscope for photoconversion. And finally, we will show how to perform optical highlighting in live cells, including dual-probe optical highlighting with mOrange2 and Dronpa.

This protocol describes a general approach to perform photoconversion of fluorescent proteins on a confocal laser scanning microscope. We describe procedures for the photoconversion of puried protein samples, as well as for dual-probe optical highlighting in live cells with mOrange2 and Dronpa.

Photoconversion de protéines purifiées fluorescentes et double-sonde optique dans Soulignant cellules vivantes

Photoconvertible fluorescent proteins (pc-FPs) are a class of fluorescent proteins with "optical highlighter" capability, meaning that the color of ...

Patch Clamp and Perfusion Techniques for Studying Ion Channels Expressed in Xenopus oocytes

The protocol presented here is designed to study the activation of the large conductance, voltage- and Ca2+-activated K+ (BK) channels. The protocol may also be used to study the structure-function relationship for other ion channels and neurotransmitter receptors1. BK channels are widely expressed in different tissues and have been implicated in many physiological functions, including regulation of smooth muscle contraction, frequency tuning of inner hair cells and regulation of neurotransmitter release2-6. BK channels are activated by membrane depolarization and by intracellular Ca2+ and Mg2+ 6-9. Therefore, the protocol is designed to control both the membrane voltage and the intracellular solution. In this protocol, messenger RNA of BK channels is injected into Xenopus laevis oocytes (stage V-VI) followed by 2-5 days of incubation at 18&deg;C10-13. Membrane patches that contain single or multiple BK channels are excised with the inside-out configuration using patch clamp techniques10-13. The intracellular side of the patch is perfused with desired solutions during recording so that the channel activation under different conditions can be examined. To summarize, the mRNA of BK channels is injected into Xenopus laevis oocytes to express channel proteins on the oocyte membrane; patch clamp techniques are used to record currents flowing through the channels under controlled voltage and intracellular solutions.

Patch Clamp and Perfusion Techniques for Studying Ion Channels Expressed in Xenopus oocytes

Ionic current of BK channels is recorded using patch clamp techniques. BK channels are expressed in Xenopus oocytes by injecting messenger RNA. The intracellular solution during patch clamp recordings is controlled by a perfusion system.

Patch Clamp et des techniques de perfusion pour étudier les canaux ioniques Exprimé en Xenopus Ovocytes

The protocol presented here is designed to study the activation of the large conductance, voltage- and Ca2+-activated K+ (BK) channels. The protocol may ...

Rapid Genetic Analysis of Epithelial-Mesenchymal Signaling During Hair Regeneration

Hair follicle morphogenesis, a complex process requiring interaction between epithelia-derived keratinocytes and the underlying mesenchyme, is an attractive model system to study organ development and tissue-specific signaling. Although hair follicle development is genetically tractable, fast and reproducible analysis of factors essential for this process remains a challenge. Here we describe a procedure to generate targeted overexpression or shRNA-mediated knockdown of factors using lentivirus in a tissue-specific manner. Using a modified version of a hair regeneration model 5, 6, 11, we can achieve robust gain- or loss-of-function analysis in primary mouse keratinocytes or dermal cells to facilitate study of epithelial-mesenchymal signaling pathways that lead to hair follicle morphogenesis. We describe how to isolate fresh primary mouse keratinocytes and dermal cells, which contain dermal papilla cells and their precursors, deliver lentivirus containing either shRNA or cDNA to one of the cell populations, and combine the cells to generate fully formed hair follicles on the backs of nude mice. This approach allows analysis of tissue-specific factors required to generate hair follicles within three weeks and provides a fast and convenient companion to existing genetic models.

Tissue-specific analysis of a hair follicle regeneration model using lentivirus to mediate gain- or loss-of-function.

Analyse rapide de la génétique des épithélio-mésenchymateuse signalisation lors de la régénération des cheveux

Hair follicle morphogenesis, a complex process requiring interaction between epithelia-derived keratinocytes and the underlying mesenchyme, is an ...

Intravital Microscopy for Imaging Subcellular Structures in Live Mice Expressing Fluorescent Proteins

Here we describe a procedure to image subcellular structures in live rodents that is based on the use of confocal intravital microscopy. As a model organ, we use the salivary glands of live mice since they provide several advantages. First, they can be easily exposed to enable access to the optics, and stabilized to facilitate the reduction of the motion artifacts due to heartbeat and respiration. This significantly facilitates imaging and tracking small subcellular structures. Second, most of the cell populations of the salivary glands are accessible from the surface of the organ. This permits the use of confocal microscopy that has a higher spatial resolution than other techniques that have been used for in vivo imaging, such as two-photon microscopy. Finally, salivary glands can be easily manipulated pharmacologically and genetically, thus providing a robust system to investigate biological processes at a molecular level.
In this study we focus on a protocol designed to follow the kinetics of the exocytosis of secretory granules in acinar cells and the dynamics of the apical plasma membrane where the secretory granules fuse upon stimulation of the beta-adrenergic receptors. Specifically, we used a transgenic mouse that co-expresses cytosolic GFP and a membrane-targeted peptide fused with the fluorescent protein tandem-Tomato. However, the procedures that we used to stabilize and image the salivary glands can be extended to other mouse models and coupled to other approaches to label in vivo cellular components, enabling the visualization of various subcellular structures, such as endosomes, lysosomes, mitochondria, and the actin cytoskeleton.

Intravital microscopy is a powerful tool that enables imaging various biological processes in live animals. In this article, we present a detailed method for imaging the dynamics of subcellular structures, such as the secretory granules, in the salivary glands of live mice.

Microscopie intravitale pour l&#39;imagerie Subcellular ouvrages chez des souris vivantes exprimant des protéines fluorescentes

Here we describe a procedure to image subcellular structures in live rodents that is based on the use of confocal intravital microscopy. As a model organ, ...

Facial Transplants in Xenopus laevis Embryos

Craniofacial birth defects occur in 1 out of every 700 live births, but etiology is rarely known due to limited understanding of craniofacial development. To identify where signaling pathways and tissues act during patterning of the developing face, a 'face transplant' technique has been developed in embryos of the frog Xenopus laevis. A region of presumptive facial tissue (the "Extreme Anterior Domain" (EAD)) is removed from a donor embryo at tailbud stage, and transplanted to a host embryo of the same stage, from which the equivalent region has been removed. This can be used to generate a chimeric face where the host or donor tissue has a loss or gain of function in a gene, and/or includes a lineage label. After healing, the outcome of development is monitored, and indicates roles of the signaling pathway within the donor or surrounding host tissues. Xenopus is a valuable model for face development, as the facial region is large and readily accessible for micromanipulation. Many embryos can be assayed, over a short time period since development occurs rapidly. Findings in the frog are relevant to human development, since craniofacial processes appear conserved between Xenopus and mammals.

Facial Transplants in Xenopus laevis Embryos

A technique for transplanting "Extreme Anterior Domain" facial tissue between Xenopus laevis embryos has been developed. Tissue can be moved from one gene expression background into another, allowing the study of local requirements for craniofacial development and for signaling interactions between facial regions.

Transplantations faciales<em&gt; Xenopus laevis</em&gt; Embryons

Craniofacial birth defects occur in 1 out of every 700 live births, but etiology is rarely known due to limited understanding of craniofacial development. ...

The Xenopus Oocyte Cut-open Vaseline Gap Voltage-clamp Technique With Fluorometry

The cut-open oocyte Vaseline gap (COVG) voltage clamp technique allows for analysis of electrophysiological and kinetic properties of heterologous ion channels in oocytes. Recordings from the cut-open setup are particularly useful for resolving low magnitude gating currents, rapid ionic current activation, and deactivation. The main benefits over the two-electrode voltage clamp (TEVC) technique include increased clamp speed, improved signal-to-noise ratio, and the ability to modulate the intracellular and extracellular milieu.
Here, we employ the human cardiac sodium channel (hNaV1.5), expressed in Xenopus oocytes, to demonstrate the cut-open setup and protocol as well as modifications that are required to add voltage clamp fluorometry capability.
The properties of fast activating ion channels, such as hNaV1.5, cannot be fully resolved near room temperature using TEVC, in which the entirety of the oocyte membrane is clamped, making voltage control difficult. However, in the cut-open technique, isolation of only a small portion of the cell membrane allows for the rapid clamping required to accurately record fast kinetics while preventing channel run-down associated with patch clamp techniques.
In conjunction with the COVG technique, ion channel kinetics and electrophysiological properties can be further assayed by using voltage clamp fluorometry, where protein motion is tracked via cysteine conjugation of extracellularly applied fluorophores, insertion of genetically encoded fluorescent proteins, or the incorporation of unnatural amino acids into the region of interest1. This additional data yields kinetic information about voltage-dependent conformational rearrangements of the protein via changes in the microenvironment surrounding the fluorescent molecule.

The Xenopus Oocyte Cut-open Vaseline Gap Voltage-clamp Technique With Fluorometry

The cut-open Vaseline gap approach is used to obtain low noise recordings of ionic and gating currents from voltage-dependent ion channels expressed in Xenopus oocytes with high resolution of fast channel kinetics. With minor modification, voltage clamp fluorometry can be coupled to the cut-open oocyte protocol.

La<em&gt; Xenopus</em&gt; Ovocytes Cut-ouvert vaseline Gap voltage-clamp Technique Avec Fluorimétrie

The cut-open oocyte Vaseline gap (COVG) voltage clamp technique allows for analysis of electrophysiological and kinetic properties of heterologous ion ...

Reconstitution Of &#946;-catenin Degradation In Xenopus Egg Extract

Xenopus laevis egg extract is a well-characterized, robust system for studying the biochemistry of diverse cellular processes. Xenopus egg extract has been used to study protein turnover in many cellular contexts, including the cell cycle and signal transduction pathways1-3. Herein, a method is described for isolating Xenopus egg extract that has been optimized to promote the degradation of the critical Wnt pathway component, &beta;-catenin. Two different methods are described to assess &beta;-catenin protein degradation in Xenopus egg extract. One method is visually informative ([35S]-radiolabeled proteins), while the other is more readily scaled for high-throughput assays (firefly luciferase-tagged fusion proteins). The techniques described can be used to, but are not limited to, assess &beta;-catenin protein turnover and identify molecular components contributing to its turnover. Additionally, the ability to purify large volumes of homogenous Xenopus egg extract combined with the quantitative and facile readout of luciferase-tagged proteins allows this system to be easily adapted for high-throughput screening for modulators of &beta;-catenin degradation.

Reconstitution Of &amp;#946;-catenin Degradation In Xenopus Egg Extract

A method is described for analyzing protein degradation using radiolabeled and luciferase-fusion proteins in Xenopus egg extract and its adaptation for high-throughput screening for small molecule modulators of protein degradation.

Reconstitution de β-caténine dégradation dans<em&gt; Xenopus</em&gt; Extrait des oeufs

Xenopus laevis egg extract is a well-characterized, robust system for studying the biochemistry of diverse cellular processes. Xenopus egg extract has ...

Quantification of Orofacial Phenotypes in Xenopus

Xenopus has become an important tool for dissecting the mechanisms governing craniofacial development and defects. A method to quantify orofacial development will allow for more rigorous analysis of orofacial phenotypes upon abrogation with substances that can genetically or molecularly manipulate gene expression or protein function. Using two dimensional images of the embryonic heads, traditional size dimensions-such as orofacial width, height and area- are measured. In addition, a roundness measure of the embryonic mouth opening is used to describe the shape of the mouth. Geometric morphometrics of these two dimensional images is also performed to provide a more sophisticated view of changes in the shape of the orofacial region. Landmarks are assigned to specific points in the orofacial region and coordinates are created. A principle component analysis is used to reduce landmark coordinates to principle components that then discriminate the treatment groups. These results are displayed as a scatter plot in which individuals with similar orofacial shapes cluster together. It is also useful to perform a discriminant function analysis, which statistically compares the positions of the landmarks between two treatment groups. This analysis is displayed on a transformation grid where changes in landmark position are viewed as vectors. A grid is superimposed on these vectors so that a warping pattern is displayed to show where significant landmark positions have changed. Shape changes in the discriminant function analysis are based on a statistical measure, and therefore can be evaluated by a p-value. This analysis is simple and accessible, requiring only a stereoscope and freeware software, and thus will be a valuable research and teaching resource.

Quantification of Orofacial Phenotypes in Xenopus

A method to quantify the orofacial size and shape of Xenopus laevis embryos has been developed. In this protocol, traditional size measurements are combined with geometric morphometrics to allow for more sophisticated analyses of orofacial development and defects.

Quantification de Orofacial phénotypes dans<em&gt; Xenopus</em

Xenopus has become an important tool for dissecting the mechanisms governing craniofacial development and defects. A method to quantify orofacial ...

Measuring Glutathione-induced Feeding Response in Hydra

Hydra is among the most primitive organisms possessing a nervous system and chemosensation for detecting reduced glutathione (GSH) for capturing the prey. The movement of prey organisms causes mechanosensory discharge of the stinging cells called nematocysts from hydra, which are inserted into the prey. The feeding response in hydra, which includes curling of the tentacles to bring the prey towards the mouth, opening of the mouth and consequent engulfing of the prey, is triggered by GSH present in the fluid released from the injured prey. To be able to identify the molecular mechanism of the feeding response in hydra which is unknown to date, it is necessary to establish an assay to measure the feeding response. Here, we describe a simple method for the quantitation of the feeding response in which the distance between the apical end of the tentacle and mouth of hydra is measured and the ratio of such distance before and after the addition of GSH is determined. The ratio, called the relative tentacle spread, was found to give a measure of the feeding response. This assay was validated using a starvation model in which starved hydra show an enhanced feeding response in comparison with daily fed hydra.

Here we describe a simple assay for the quantification of the feeding response in hydra induced by the reduced form of glutathione. This assay relies on measuring the distance between the apical end of the tentacle and mouth of hydra.

Mesure induite glutathion-réponse d&#39;alimentation à Hydra

Hydra is among the most primitive organisms possessing a nervous system and chemosensation for detecting reduced glutathione (GSH) for capturing the prey. ...

Translocation polarisée des protéines fluorescentes dans les Xenopus en réponse à la signalisation Wnt