La ricerca nel laboratorio Sokol è patrocinata dal Institues Nazionale di Salute.

1. Fecondazione in vitro di uova di Xenopus <ol><li> Ottenere le uova da rane femminile che sono stati iniettati con gonadotropina corionica umana (400 unità / rana) 12 ore prima dell&#39;esperimento. </li><li> Mettere le uova in una piccola quantità (0.5-1 ml) di soluzione 1 x Marc Ringer modificati (MMR) 10 per le uova e fecondare in vitro con un piccolo pezzo di testicolo sezionato. Dopo 2-3 minuti, aggiungere 0,1 x MMR per coprire tutta la superficie delle uova. In 20 minuti, uova cappotto gelatina viene rimosso da 3% cisteina - HCL (portata a pH 8 con idrossido di sodio). Le uova vengono lavate con 0,1 x MMR tre volte e lasciato in un freddo incubatore (13 ° C) per preparazioni iniettabili. </li><li> Uova fecondate sono permesso di sviluppare a 2-4 stadio cellulare. Per preparazioni iniettabili, gli embrioni vengono trasferiti nella soluzione contenente il 3% Ficoll, 0,5 x MMR. </li></ol> 2. RNA Microiniezione <ol><li> RNA vengono sintetizzate dai modelli di DNA linearizzato utilizzando mMessage mMachine kit (Ambion) e diluita con acqua RNase-free alla concentrazione stock di 0,1-1 mg / mL. Dosi ottimali di RNA per preparazioni iniettabili sono determinati in esperimenti pilota. RNA per Diversin-RFP, il marcatore membrana GFP-CAAX Frizzled e 8 sono utilizzati al 0,1-1 ng per iniezione. </li><li> Gli aghi da iniezione sono preparati con un estrattore ago da una capillare e poi con una smerigliatrice ago. Prima dell&#39;iniezione, ogni ago è calibrato con acqua per espellere 10 nl di iniezione di liquido per. </li><li> Per preparazioni iniettabili, gli embrioni sono posti su un piatto di plastica in una grande goccia del 3% Ficoll, 0,5 x MMR. Una microlitri di soluzione RNA è risucchiata in un ago da iniezione con Narishige microinjector. 10 nl di RNA viene iniettato in blastomeri animali embrioni di 8 cellule 2-3 volte. Gli embrioni iniettati vengono trasferiti in un pozzo di 12-pozzetti. </li></ol> 3. Preparazione ectodermica Espianti <ol><li> Quando gli embrioni iniettati raggiungere presto stadio di gastrula, vengono trasferiti in una soluzione 0,6 x MMR in un piatto di 3 centimetri di plastica rivestiti con 1% di agarosio. Membrana vitellina viene rimosso manualmente con un paio di pinze. Espianti ectodermica sono asportati dagli embrioni utilizzando un ago di tungsteno e un hairloop. </li><li> Espianti ectodermica vengono trasferiti in un flacone di vetro e fissato con 3,7% di formaldeide in soluzione salina tamponata con fosfato (PBS) per 30 minuti. Espianti fissi vengono lavati con PBS per tre volte (10 minuti ciascuno). DAPI è incluso nel terzo lavaggio a macchia nuclei. </li><li> Espianti sono montati su un vetrino. Due strisce di nastro adesivo sono attaccati alla slitta e la espianti sono posti tra le due strisce. Dal momento che la superficie esterna di espianti è pigmentata, la parte interna del espianti deve essere rivolto l&#39;obiettivo microscopio. Aggiungere 2-3 gocce 20 ml di soluzione di montaggio (70% glicerolo in PBS di cui 25 mg / ml DABCO, anti-sbiadimento reagente) 11. Mettere un coprioggetti sopra. </li></ol> 4. Imaging di Espianti al microscopio a fluorescenza <ol><li> I campioni sono visti al microscopio Zeiss Axioplan a fluorescenza con filtri appropriati. </li><li> Le immagini sono scattate con l&#39;attaccamento Apotome di visualizzare uno specifico piano da diversi espianti indipendenti. </li></ol> 5. Criosezionamento Criosezionamento è un modo alternativo per visualizzare la distribuzione delle proteine ​​fluorescenti nella cella e più applicabile per immunocolorazione. Nella fase 10, gli embrioni sono fissati per 1-2 ore con fissativo Dent (20% DMSO, 80% metanolo), lavate con PBS, e incorporate nel 15% soluzione di saccarosio pesce gelatin/15% 11. Gli embrioni congelati sono rapidamente integrati in ghiaccio secco e criosezioni sono generate su Leica criostato. Sezioni che comprendono le cellule ectodermiche che ereditano RNA iniettato e loro prodotti proteici tradotte. Le sezioni mantenere fluorescenza e può essere immunoistochimica con anticorpi specifici e poi etichettati con anticorpi secondari coniugati con fluorescenza. I nuclei sono colorati con DAPI. I mezzi di montaggio sono gli stessi come descritto sopra. L&#39;imaging può essere eseguita come descritto sopra. 6. Rappresentante dei risultati: <img src="/files/ftp_upload/2700/2700fig1.jpg" alt="Figura 1" /> Figura 1. Recettore Frizzled reclute Diversin alla membrana cellulare. Cellule che esprimono Ectoderma 8 Frizzled (Xfz8) e Div-RFP RNA rivelare Div-RFP a livello della membrana cellulare, al posto del centrosoma (come rivelato da g-tubulina co-scarico). Lo schema dell&#39;esperimento è al top, una tipica sezione trasversale è mostrato.

<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>

Nessun conflitto di interessi dichiarati.

Abbiamo usato il protocollo di cui sopra per caratterizzare la localizzazione subcellulare di Diversin. In espianti polo animale, Diversin-RFP è stata rilevata accanto al nucleo e colocalized con g-tubulina, un marker centrosomica, in criosezioni (Figura 1). Una volta che la localizzazione subcellulare di una proteina è identificato, costruisce la cancellazione può essere generata per stabilire quali domini di proteine ​​sono necessarie e sufficienti per la localizzazione subcellulare. Usando questo approccio, i ...

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

Polarità delle cellule è una proprietà fondamentale delle cellule eucariotiche che viene dinamicamente regolato da fattori intrinseci ed estrinseci, sia durante lo sviluppo embrionale 1, 2. Una delle vie di segnalazione coinvolte nel presente regolamento è la via Wnt, che viene utilizzato più volte durante l&#39;embriogenesi e critica per la malattia umana 3, 4, 5. Molteplici componenti molecolari di questa via di segnalazione coordinatamente regolano in maniera spazialmente limitato, ma i meccanismi alla base non sono pienamente compresi. Xenopus cellule embrionali epiteliali è un ottimo sistema per studiare la localizzazione subcellulare delle diverse proteine ​​di segnalazione. Proteine ​​di fusione fluorescenti sono espressi in embrioni di Xenopus da microiniezione di RNA, gli espianti ectodermiche sono preparati e la localizzazione delle proteine ​​viene valutato epifluorescenza. In questo protocollo sperimentale descriviamo come localizzazione subcellulare di Diversin, una proteina citoplasmatica che è stato implicato nella segnalazione e polarità determinazione delle cellule 6, 7 viene visualizzato in Xenopus cellule ectodermiche per lo studio di trasduzione del segnale Wnt 8. Coespressione di un ligando Wnt o un recettore Frizzled altera la distribuzione di Diversin fuse con il rosso proteina fluorescente, RFP, e reclute alla membrana cellulare in maniera polarizzata 8, 9. Questo protocollo ex vivo dovrebbe essere un&#39;utile aggiunta a studi in vitro su colture di cellule di mammifero, in cui il controllo spaziale del segnale è diversa da quella del tessuto intatto ed è molto più difficile da analizzare.

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 ectoderma embrionale è diventato un modello attraente per gli studi di polarità cellulare. Un saggio è descritta, in cui la distribuzione subcellulare delle proteine ​​fluorescenti è valutata in cellule ectoderma. Questo protocollo aiuterà a trattare questioni relative al controllo spaziale della segnalazione.

Traslocazione polarizzato di proteine ​​fluorescenti in Xenopus</emEctoderma> in risposta alla segnalazione 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 Views.  Mount Sinai School of Medicine. Xenopus ectoderma embrionale è diventato un modello attraente per gli studi di polarità cellulare. Un saggio è descritta, in cui la distribuzione subcellulare delle proteine ​​fluorescenti è valutata in cellule ectoderma. Questo protocollo aiuterà a trattare questioni relative al controllo spaziale della segnalazione.

Video: 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.

Quantificazione dei γH2AX Foci in risposta alle radiazioni ionizzanti

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

Ricerca

Biologia

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.

Fotoconversione di proteine ​​purificate fluorescenti ed evidenziazione ottica dual-sonda in cellule vive

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 e Tecniche di perfusione per la valutazione dei canali ioni Espresso in Xenopus Ovociti

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.

Rapida analisi genetica di epitelio-mesenchimale segnalazione durante la rigenerazione dei capelli

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.

Intravitale Microscopia per le strutture Imaging subcellulari in topi vivi Esprimere proteine ​​fluorescenti

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.

Trapianti viso a<em&gt; Xenopus laevis</em&gt; Embrioni

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.

Il<em&gt; Xenopus</em&gt; Ovociti Cut-open vaselina Gap Tecnica Voltage-clamp Con fluorometria

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.

Ricostituzione della β-catenina degradazione nel<em&gt; Xenopus</em&gt; Estrai Egg

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.

Quantificazione di orofacciale fenotipi in<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.

Misurazione glutatione indotta risposta alimentazione a Hydra

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

Traslocazione polarizzato di proteine ​​fluorescenti in Xenopus in risposta alla segnalazione Wnt

Traslocazione polarizzato di proteine fluorescenti in Xenopus in risposta alla segnalazione Wnt