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1. La disección del segmento anterior. <ol><li> Tejido escleral por detrás del limbo se toma con una pinza 0,22 y el globo (globo ocular) se estabiliza. </li><li> Una hoja de microcirugía se utiliza para hacer una incisión lineal en la córnea de limbo a limbo. </li><li> Un 0,12 Colibri pinza se utiliza para captar la córnea en la incisión. </li><li> El líquido de la cámara anterior es absorbido con una lanza Weck-Cel quirúrgica. </li></ol> 2. Lente de la evisceración. <ol><li> Un 0,12 Colibri pinza agarrando la córnea se utiliza para estabilizar el mundo. </li><li> El titular de una fina aguja curva (curva o fórceps vestir) se inserta detrás de la lente hacia la parte posterior del globo. El titular de la aguja está parcialmente cerrada, y tiró hacia adelante. La presión se aplica con las pinzas en la superficie externa de la esclerótica, que empuja la lente hacia adelante a través de la incisión en la córnea, dejando intacta la pared del ojo. El humor vítreo se presenta como un gel translúcido y está parcialmente adherida a la lente. </li><li> El tejido del cristalino, humor vítreo se coloca en un tubo de centrifugación filtrado contiene 20 microlitros de cóctel de inhibidores de la proteasa (Roche) disuelto en PBS. </li></ol> 3. Retina evisceración. <ol><li> Seguir para estabilizar el mundo, con 0,12 fórceps Colibri captar la incisión en la córnea. </li><li> El titular de una fina aguja curva (curva o fórceps vestir) se coloca en lo posterior para el mundo como sea posible, cerca del nervio óptico. El titular de la aguja está parcialmente cerrada, y tiró hacia adelante. La presión se aplica con las pinzas en la superficie externa de la esclerótica, que empuja la retina hacia delante a través de la incisión en la córnea. El humor vítreo se presenta como un gel transparente adheridas a la retina. La retina es visualizado como un pañuelo amarillo, vascularizado. Las tiras de tejido pigmentado puede ser desprendido con pinzas. </li><li> El tejido de la retina-vítreo se coloca en el tubo de centrífuga de filtrado que contiene el tejido de lente vítreo. </li></ol> 4. Filtrada centrifugación. <ol><li> El tubo de centrífuga de filtrado se coloca en una centrífuga de mesa. Giran a 14.000 x G durante 12 minutos. </li><li> Aspirar el eluyente de la cámara baja, que es el humor vítreo. La retina permanece en la cámara alta. Estas muestras pueden ser utilizados para los estudios de las proteínas. </li></ol> 5. Resultados representante Muestras de humor vítreo fueron analizadas por SDS-PAGE (Figura 2). Las muestras también fueron utilizados para un ensayo de actividad enzimática (Figura 3). <img src="/files/ftp_upload/2795/2795fig1.jpg" alt="Figura 1"/> Figura 1. Diagrama del ojo del ratón. La sección transversal esquemática del ojo humano y el ratón se muestra la relación de menor volumen vítreo en el ojo del ratón gracias a su lente más grande. <img src="/files/ftp_upload/2795/2795fig2.jpg" alt="Figura 2"/> Figura 2. Unidimensional SDS-PAGE del vítreo y la retina del ratón. Los perfiles de proteínas de vítreo del ratón, el 13,6 mg / mL (carril 1), y la retina, 11,35 mg / mL (carril 2). Electroforesis en gel se realizó en 150 kV durante 45 minutos, se tiñeron con tinción de Flamingo gel fluorescente y se visualizan mediante un sistema de VersaDoc Imaging (BioRad, Hercules, CA). <img src="/files/ftp_upload/2795/2795fig3.jpg" alt="Figura 3"/> Figura 3. Superóxido dismutasa (SOD) de la actividad enzimática en el ratón y el humor vítreo humano. Medición de la actividad total de SOD (SOD actividad colorimétrico aasay kit, # AB65354, Abcam, Inc., Cambridge, MA) se llevó a cabo en el vítreo y la retina recogidos por la evisceración de los ratones DBA y albino. Esto se comparó con la actividad de SOD en el núcleo humano vítreo y la retina humana proveniente de post-mortem ojos de donantes humanos para determinar la actividad relativa. Sin diluir las muestras de núcleo vítreo aspirado manualmente usando una aguja de calibre 23, 11 y en la retina fue recogido por la floración a los ojos y cortar el tejido del complejo EPR ​​/ coroides. Aunque la prueba no distingue entre las isoformas de SOD, la actividad de la SOD vítreo es probable que refleje SOD3, ya que es la isoforma extracelular sólo 12 La actividad de la SOD retina es probable que refleje todas las isoformas de SOD tres:. Intracelular SOD1, SOD2 mitocondrial y extracelular SOD3. 12 Para los ensayos enzimáticos de alta sensibilidad, la inclusión de este ensayo de SOD, la posibilidad de contaminación cruzada de las proteínas es posible y requiere más estudio. Las barras de error representan el SEM.

<ol>
	<li>Bishop, P. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Structural+macromolecules+and+supramolecular+organisation+of+the+vitreous+gel.">Structural macromolecules and supramolecular organisation of the vitreous gel.</a> Prog. Retin. Eye Res. 19, 323-344 (2000).</li><li>Gao, B. B., Chen, X., Timothy, N., Aiello, L. P. &. a. m. p. ;. a. m. p., Feener, E. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+of+the+vitreous+proteome+in+diabetes+without+diabetic+retinopathy+and+diabetes+with+proliferative+diabetic+retinopathy.">Characterization of the vitreous proteome in diabetes without diabetic retinopathy and diabetes with proliferative diabetic retinopathy.</a> J. Proteome Res. 7, 2516-2525 (2008).</li><li>Izuta, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Extracellular+SOD+and+VEGF+are+increased+in+vitreous+bodies+from+proliferative+diabetic+retinopathy+patients.">Extracellular SOD and VEGF are increased in vitreous bodies from proliferative diabetic retinopathy patients.</a> Mol. Vis. 15, 2663-2672 (2009).</li><li>Sebag, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Molecular+biology+of+pharmacologic+vitreolysis.">Molecular biology of pharmacologic vitreolysis.</a> Trans. Am. Ophthalmol. Soc. 103, 473-494 (2005).</li><li>Smith, R. S., Smith, R. S., John, S. W. M., Nishina, P. M., Sundberg, J. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Systematic evaluation of the mouse eye: Anatomy, pathology, and biomethods. , 161-195 (2002).</li><li>Ihanamaki, T., Metsaranta, M., Rintala, M., Vuorio, E., Sandberg-Lall, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ocular+abnormalities+in+transgenic+mice+harboring+mutations+in+the+type+II+collagen+gene.">Ocular abnormalities in transgenic mice harboring mutations in the type II collagen gene.</a> Eur. J. Ophthalmol. 6, 427-435 (1996).</li><li>Kaarniranta, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+mouse+model+for+Stickler's+syndrome:+ocular+phenotype+of+mice+carrying+a+targeted+heterozygous+inactivation+of+type+II+(pro)collagen+gene+(Col2a1.">A mouse model for Stickler's syndrome: ocular phenotype of mice carrying a targeted heterozygous inactivation of type II (pro)collagen gene (Col2a1.</a> Exp. Eye Res. 83, 297-303 (2006).</li><li>Marneros, A. G. &. a. m. p. ;. a. m. p., Olsen, B. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Age-dependent+iris+abnormalities+in+collagen+XVIII/endostatin+deficient+mice+with+similarities+to+human+pigment+dispersion+syndrome.">Age-dependent iris abnormalities in collagen XVIII/endostatin deficient mice with similarities to human pigment dispersion syndrome.</a> Invest. Ophthalmol. Vis. Sci. 44, 2367-2372 (2003).</li><li>Martin, A. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pathogenesis+of+persistent+hyperplastic+primary+vitreous+in+mice+lacking+the+arf+tumor+suppressor+gene.">Pathogenesis of persistent hyperplastic primary vitreous in mice lacking the arf tumor suppressor gene.</a> Invest. Ophthalmol. Vis. Sci. 45, 3387-3396 (2004).</li><li>Song, B. J., Tsang, S. H., Lin, C. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Genetic+models+of+retinal+degeneration+and+targets+for+gene+therapy.">Genetic models of retinal degeneration and targets for gene therapy.</a> Gene. Ther. Mol. Biol. 11B, 229-262 (2007).</li><li>Skeie, J. M., Mahajan, V. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dissection+of+Human+Vitreous+Body+Elements+for+Proteomic+Analysis.">Dissection of Human Vitreous Body Elements for Proteomic Analysis.</a> J Vis Exp. , (2011).</li><li>Ciechanowski, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Impaired+synthesis+is+not+the+reason+for+decreased+activity+of+extracellular+superoxide+dismutase+in+patients+with+diabetes.">Impaired synthesis is not the reason for decreased activity of extracellular superoxide dismutase in patients with diabetes.</a> Arch Med Res. 36, 148-153 (2005).</li></ol>

Los experimentos con animales se realizaron de acuerdo con la Asociación para la Investigación y Visión en la declaración de Oftalmología para el uso de animales en Oftálmica y Vision Research.

Los ratones transgénicos son un importante modelo para la investigación de enfermedades de la retina y vítreo-retiniana. 10.6 El cuerpo vítreo del ratón, sin embargo, cuenta con una proporción significativamente menor de los ojos, en comparación con el humor vítreo humanos debido a la gran lente en el ojo del ratón. 5 Esto hace que es difícil aislar y purificar el cuerpo vítreo del ratón. Comprender los cambios asociados a la proteína del vítreo en enfermedades como la retinopatía diabética proliferativa, relacionada con la edad degeneración macular, uveítis, desprendimiento de retina y le dará información sobre los mecanismos por los cuales el progreso. Este protocolo experimental visualizar proporciona un medio para obtener y purificar el cuerpo vítreo del ratón, al tiempo que maximiza el rendimiento de proteína para los análisis enzimáticos y proteómicos.

<table border="1"><tbody><tr><th> Nombre </th><th> Empresa </th><th> Número de catálogo </th><th> Comentarios </th></tr><tr><td> 15 °, BD Beaver Microcirugía de la hoja </td><td> Becton-Dickinson </td><td> 374881 </td><td></td></tr><tr><td> PBS, pH 7,4 </td><td> Invitrogen </td><td> 70011-044 </td><td></td></tr><tr><td> 0,22 fina sutura Castroviejo Pinzas </td><td> Storz Ophthalmics </td><td> E1805 </td><td></td></tr><tr><td> 0,12 Colibri fórceps </td><td> Storz Ophthalmics </td><td> 2 / 132 </td><td></td></tr><tr><td> Microcon centrífuga Ultracel filtro YM-100 o YM-50 </td><td> Millipore </td><td> 42412, 42415 </td><td></td></tr><tr><td> Actividad SOD Kit de ensayo colorimétrico </td><td> Abcam </td><td> Ab65354 </td><td></td></tr><tr><td> Weck-Cel quirúrgica lanzas </td><td> Medtronic </td><td> 0008680 </td><td></td></tr><tr><td> Cóctel de inhibidores de la proteasa </td><td> Roche </td><td> 11 836 170 001 </td><td></td></tr><tr><td> Flamingo gel de tinción fluorescente </td><td> Bio-Rad </td><td> 161-04910 </td><td></td></tr></tbody></table>

evisceration of mouse vitreous and retina for proteomic analyses

Mientras que la retina del ratón se ha convertido en un importante modelo genético para enfermedades hereditarias de retina, el vítreo del ratón que queda por explorar. El humor vítreo es una matriz extracelular muy acuosa que recubre la retina donde intraocular, así como las proteínas se acumulan durante la enfermedad extraocular. 1.3 interacciones anormales entre vítreo y la retina la base de varias enfermedades, tales como desprendimiento de retina, retinopatía diabética proliferativa, uveítis, y la vitreorretinopatía proliferativa. 1 , 4 El volumen relativo vítreo del ratón es significativamente menor que el vítreo humano (Figura 1), ya que la lente del ratón ocupa casi el 75% de su ojo. 5 Esto ha hecho que los estudios bioquímicos de vítreo ratón desafiante. En este artículo de vídeo, se presenta una técnica para analizar y aislar el vítreo de la retina del ratón, lo que permitirá el uso de modelos de ratones transgénicos para definir más claramente el papel de esta matriz extracelular en el desarrollo de enfermedades vítreo-retiniana.

Watch this Scientific Journal Video about Evisceration of Mouse Vitreous and Retina for Proteomic Analyses at JoVE.com

Evisceration of Mouse Vitreous and Retina for Proteomic Analyses

La técnica de disección ilustra la evisceración del vítreo, la retina y el cristalino del ojo del ratón, la separación por centrifugación, y la caracterización de los ensayos de proteínas.

Evisceración de vítreo y retina del ratón para análisis proteómico

While the mouse retina has emerged as an important genetic model for inherited retinal disease, the mouse vitreous remains to be explored. The vitreous is ...

evisceration-of-mouse-vitreous-and-retina-for-proteomic-analyses

Research

JoVE Journal

Biology

28.9K vistas.  University of Iowa. La técnica de disección ilustra la evisceración del vítreo, la retina y el cristalino del ojo del ratón, la separación por centrifugación, y la caracterización de los ensayos de proteínas.

Video: Evisceration of Mouse Vitreous and Retina for Proteomic Analyses

Electrophoretic Separation of Proteins

Electrophoresis is used to separate complex mixtures of proteins (e.g., from cells, subcellular fractions, column fractions, or immunoprecipitates), to investigate subunit compositions, and to verify homogeneity of protein samples. It can also serve to purify proteins for use in further applications. In polyacrylamide gel electrophoresis, proteins migrate in response to an electrical field through pores in a polyacrylamide gel matrix; pore size decreases with increasing acrylamide concentration. The combination of pore size and protein charge, size, and shape determines the migration rate of the protein. In this unit, the standard Laemmli method is described for discontinuous gel electrophoresis under denaturing conditions, i.e., in the presence of sodium dodecyl sulfate (SDS). 

In this video, we demonstrate a method for electrophoretic separation of proteins using poly-acrylimide gel electrophoresis (PAGE).

Separación electroforética de las proteínas

Electrophoresis is used to separate complex mixtures of proteins (e.g., from cells, subcellular fractions, column fractions, or immunoprecipitates), to ...

Investigación

Biología

Immunoblot Analysis

Immunoblotting (western blotting) is a rapid and sensitive assay for the detection and characterization of proteins that works by exploiting the specificity inherent in antigen-antibody recognition. It involves the solubilization and electrophoretic separation of proteins, glycoproteins, or lipopolysaccharides by gel electrophoresis, followed by quantitative transfer and irreversible binding to nitrocellulose, PVDF, or nylon. The immunoblotting technique has been useful in identifying specific antigens recognized by polyclonal or monoclonal antibodies and is highly sensitive (1 ng of antigen can be detected). This unit provides protocols for protein separation, blotting proteins onto membranes, immunoprobing, and visualization using chromogenic or chemiluminescent substrates.

Immunoblotting (western blotting) is a rapid and sensitive assay for the detection and characterization of proteins that works by exploiting the specificity inherent in antigen-antibody recognition. This video provides protocols for protein separation, blotting proteins onto membranes, immunoprobing, and visualization using chromogenic or chemiluminescent substrates.

El análisis por inmunotransferencia

Immunoblotting (western blotting) is a rapid and sensitive assay for the detection and characterization of proteins that works by exploiting the ...

Staining Proteins in Gels

Following separation by electrophoretic methods, proteins in a gel can be detected by several staining methods. This unit describes protocols for detecting proteins by four popular methods. Coomassie blue staining is an easy and rapid method. Silver staining, while more time consuming, is considerably more sensitive and can thus be used to detect smaller amounts of protein. Fluorescent staining is a popular alternative to traditional staining procedures, mainly because it is more sensitive than Coomassie staining, and is often as sensitive as silver staining. Staining of proteins with SYPRO Orange and SYPRO Ruby are also demonstrated here.

Following separation by electrophoretic methods, proteins in a gel can be detected by several staining methods. Staining of proteins with Coomassie Blue, Silver Staining, SYPRO Orange, SYPRO Ruby are demonstrated in this video.

Tinción de proteínas en geles de

Following separation by electrophoretic methods, proteins in a gel can be detected by several staining methods. This unit describes protocols for ...

Digital Microfluidics for Automated Proteomic Processing

Clinical proteomics has emerged as an important new discipline, promising the discovery of biomarkers that will be useful for early diagnosis and prognosis of disease. While clinical proteomic methods vary widely, a common characteristic is the need for (i) extraction of proteins from extremely heterogeneous fluids (i.e. serum, whole blood, etc.) and (ii) extensive biochemical processing prior to analysis. Here, we report a new digital microfluidics (DMF) based method integrating several processing steps used in clinical proteomics. This includes protein extraction, resolubilization, reduction, alkylation and enzymatic digestion. Digital microfluidics is a microscale fluid-handling technique in which nanoliter-microliter sized droplets are manipulated on an open surface. Droplets are positioned on top of an array of electrodes that are coated by a dielectric layer - when an electrical potential is applied to the droplet, charges accumulate on either side of the dielectric. The charges serve as electrostatic handles that can be used to control droplet position, and by biasing a sequence of electrodes in series, droplets can be made to dispense, move, merge, mix, and split on the surface. Therefore, DMF is a natural fit for carrying rapid, sequential, multistep, miniaturized automated biochemical assays. This represents a significant advance over conventional methods (relying on manual pipetting or robots), and has the potential to be a useful new tool in clinical proteomics.
Mais J. Jebrail, Vivienne N. Luk, and Steve C. C. Shih contributed equally to this work.
Sergio L. S. Freire's current address is at the University of the Sciences in Philadelphia located at 600 South 43rd Street, Philadelphia, PA 19104.

Digital Microfluidics is a technique characterized by the manipulation of discrete droplets (~nL - mL) on an array of electrodes by the application of electrical fields. It is well-suited for carrying out rapid, sequential, miniaturized automated biochemical assays. Here, we report a platform capable of automating several proteomic processing steps.

Microfluídica digitales para el procesamiento automatizado de Proteómica

Clinical proteomics has emerged as an important new discipline, promising the discovery of biomarkers that will be useful for early diagnosis and ...

Toxin Induction and Protein Extraction from Fusarium spp. Cultures for Proteomic Studies

Fusaria are filamentous fungi able to produce different toxins. Fusarium mycotoxins such as deoxynivalenol, nivalenol, T2, zearelenone, fusaric acid, moniliformin, etc... have adverse effects on both human and animal health and some are considered as pathogenicity factors. Proteomic studies showed to be effective for deciphering toxin production mechanisms (Taylor et al., 2008) as well as for identifying potential pathogenic factors (Paper et al., 2007, Houterman et al., 2007) in Fusaria. It becomes therefore fundamental to establish reliable methods for comparing between proteomic studies in order to rely on true differences found in protein expression among experiments, strains and laboratories. The procedure that will be described should contribute to an increased level of standardization of proteomic procedures by two ways. The filmed protocol is used to increase the level of details that can be described precisely. Moreover, the availability of standardized procedures to process biological replicates should guarantee a higher robustness of data, taking into account also the human factor within the technical reproducibility of the extraction procedure.
The protocol described requires 16 days for its completion: fourteen days for cultures and two days for protein extraction (figure 1). 
Briefly, Fusarium strains are grown on solid media for 4 days; they are then manually fragmented and transferred into a modified toxin inducing media (Jiao et al., 2008) for 10 days. Mycelium is collected by filtration through a Miracloth layer. Grinding is performed in a cold chamber. Different operators performed extraction replicates (n=3) in order to take into account the bias due to technical variations (figure 2). Extraction was based on a SDS/DTT buffer as described in Taylor et al. (2008) with slight modifications. Total protein extraction required a precipitation process of the proteins using Aceton/TCA/DTT buffer overnight and Acetone /DTT washing (figure 3a,3b). Proteins were finally resolubilized in the protein-labelling buffer and quantified. Results of the extraction were visualized on a 1D gel (Figure 4, SDS-PAGE), before proceeding to 2D gels (IEF/SDS-PAGE). The same procedure can be applied for proteomic analyses on other growing media and other filamentous fungi (Miles et al., 2007).

Toxin Induction and Protein Extraction from Fusarium spp. Cultures for Proteomic Studies

Protein extraction for proteomic analyses in fungal species requires high levels of standardization to be accomplished according with the minimum information about a proteomic experiment (MIAPE) guidelines. We present a video-protocol that includes a procedure for minimizing experimental bias during toxin induction and protein extraction from Fusarium spp.

La toxina de inducción y extracción de proteínas a partir de Fusarium Spp. Los cultivos para los estudios proteómicos

Fusaria are filamentous fungi able to produce different toxins. Fusarium mycotoxins such as deoxynivalenol, nivalenol, T2, zearelenone, fusaric acid, ...

In vivo Imaging and Therapeutic Treatments in an Orthotopic Mouse Model of Ovarian Cancer

Human cancer and response to therapy is better represented in orthotopic animal models. This paper describes the development of an orthotopic mouse model of ovarian cancer, treatment of cancer via oral delivery of drugs, and monitoring of tumor cell behavior in response to drug treatment in real time using in vivo imaging system. In this orthotopic model, ovarian tumor cells expressing luciferase are applied topically by injecting them directly into the mouse bursa where each ovary is enclosed. Upon injection of D-luciferin, a substrate of firefly luciferase, luciferase-expressing cells generate bioluminescence signals. This signal is detected by the in vivo imaging system and allows for a non-invasive means of monitoring tumor growth, distribution, and regression in individual animals. Drug administration via oral gavage allows for a maximum dosing volume of 10 mL/kg body weight to be delivered directly to the stomach and closely resembles delivery of drugs in clinical treatments. Therefore, techniques described here, development of an orthotopic mouse model of ovarian cancer, oral delivery of drugs, and in vivo imaging, are useful for better understanding of human ovarian cancer and treatment and will improve targeting this disease.

In vivo Imaging and Therapeutic Treatments in an Orthotopic Mouse Model of Ovarian Cancer

Orthotopic animal models of ovarian cancer replicate better human disease and therefore enhance our understanding of cancer progression and tumor response to therapy. A mouse model receives an intrabursal injection of luciferase-expressing ovarian tumor cells. Treatment is administered via oral gavage. Tumor growth is monitored by in vivo imaging system.

En vivo de imágenes y tratamientos terapéuticos en un modelo de ratón ortotópico de cáncer de ovario

Human cancer and response to therapy is better represented in orthotopic animal models.  This paper describes the development of an orthotopic mouse model ...

Isolation of Translating Ribosomes Containing Peptidyl-tRNAs for Functional and Structural Analyses

Recently, structural and biochemical studies have detailed many of the molecular events that occur in the ribosome during inhibition of protein synthesis by antibiotics and during nascent polypeptide synthesis. Some of these antibiotics, and regulatory nascent polypeptides mostly in the form of peptidyl-tRNAs, inhibit either peptide bond formation or translation termination1-7. These inhibitory events can stop the movement of the ribosome, a phenomenon termed "translational arrest". Translation arrest induced by either an antibiotic or a nascent polypeptide has been shown to regulate the expression of genes involved in diverse cellular functions such as cell growth, antibiotic resistance, protein translocation and cell metabolism8-13. Knowledge of how antibiotics and regulatory nascent polypeptides alter ribosome function is essential if we are to understand the complete role of the ribosome in translation, in every organism.
Here, we describe a simple methodology that can be used to purify, exclusively, for analysis, those ribosomes translating a specific mRNA and containing a specific peptidyl-tRNA14. This procedure is based on selective isolation of translating ribosomes bound to a biotin-labeled mRNA. These translational complexes are separated from other ribosomes in the same mixture, using streptavidin paramagnetic beads (SMB) and a magnetic field (MF). Biotin-labeled mRNAs are synthesized by run-off transcription assays using as templates PCR-generated DNA fragments that contain T7 transcriptional promoters. T7 RNA polymerase incorporates biotin-16-UMP from biotin-UTP; under our conditions approximately ten biotin-16-UMP molecules are incorporated in a 600 nt mRNA with a 25% UMP content. These biotin-labeled mRNAs are then isolated, and used in in vitro translation assays performed with release factor 2 (RF2)-depleted cell-free extracts obtained from Escherichia coli strains containing wild type or mutant ribosomes. Ribosomes translating the biotin-labeled mRNA sequences are stalled at the stop codon region, due to the absence of the RF2 protein, which normally accomplishes translation termination. Stalled ribosomes containing the newly synthesized peptidyl-tRNA are isolated and removed from the translation reactions using SMB and an MF. These beads only bind biotin-containing messages.
The isolated, translational complexes, can be used to analyze the structural and functional features of wild type or mutant ribosomal components, or peptidyl-tRNA sequences, as well as determining ribosome interaction with antibiotics or other molecular factors 1,14-16. To examine the function of these isolated ribosome complexes, peptidyl-transferase assays can be performed in the presence of the antibiotic puromycin1. To study structural changes in translational complexes, well established procedures can be used, such as i) crosslinking to specific amino acids14 and/or ii) alkylation protection assays1,14,17.

A major impediment to biochemical analyses of ribosomes containing nascent peptidyl-tRNAs has been the presence of other ribosomes in the same samples, ribosomes not involved in the translation of the specific mRNA sequence being analyzed. We developed a simple methodology to purify, exclusively, the ribosomes containing the nascent peptidyl-tRNA of interest.

El aislamiento de los ribosomas traducir contienen peptidil-ARNt para el Análisis Funcional y Estructural

Recently, structural and biochemical studies have detailed many of the molecular events that occur in the ribosome during inhibition of protein synthesis ...

In vivo Electroporation of Morpholinos into the Adult Zebrafish Retina

Many devastating inherited eye diseases result in progressive and irreversible blindness because humans cannot regenerate dying or diseased retinal neurons. In contrast, the adult zebrafish retina possesses the robust ability to spontaneously regenerate any neuronal class that is lost in a variety of different retinal damage models, including retinal puncture, chemical ablation, concentrated high temperature, and intense light treatment 1-8. Our lab extensively characterized regeneration of photoreceptors following constant intense light treatment and inner retinal neurons after intravitreal ouabain injection 2, 5, 9. In all cases, resident M&uuml;ller glia re-enter the cell cycle to produce neuronal progenitors, which continue to proliferate and migrate to the proper retinal layer, where they differentiate into the deficient neurons. 
	We characterized five different stages during regeneration of the light-damaged retina that were highlighted by specific cellular responses. We identified several differentially expressed genes at each stage of retinal regeneration by mRNA microarray analysis 10. Many of these genes are also critical for ocular development. To test the role of each candidate gene/protein during retinal regeneration, we needed to develop a method to conditionally limit the expression of a candidate protein only at times during regeneration of the adult retina. 
	Morpholino oligos are widely used to study loss of function of specific proteins during the development of zebrafish, Xenopus, chick, mouse, and tumors in human xenografts 11-14. These modified oligos basepair with complementary RNA sequence to either block the splicing or translation of the target RNA. Morpholinos are stable in the cell and can eliminate or "knockdown" protein expression for three to five days 12. 
	Here, we describe a method to efficiently knockdown target protein expression in the adult zebrafish retina. This method employs lissamine-tagged antisense morpholinos that are injected into the vitreous of the adult zebrafish eye. Using electrode forceps, the morpholino is then electroporated into all the cell types of the dorsal and central retina. Lissamine provides the charge on the morpholino for electroporation and can be visualized to assess the presence of the morpholino in the retinal cells. 
	Conditional knockdown in the retina can be used to examine the role of specific proteins at different times during regeneration. Additionally, this approach can be used to study the role of specific proteins in the undamaged retina, in such processes as visual transduction and visual processing in second order neurons.

In vivo Electroporation of Morpholinos into the Adult Zebrafish Retina

A method to conditionally knockdown a target protein&#x2019;s expression in the adult zebrafish retina is described, which involves intravitreally injecting antisense morpholinos and electroporating them into the retina. The resulting protein is knocked down for several days, which allows testing the protein&#x2019;s role in the regenerating or intact retina.

En electroporación in vivo de Morpholinos en la retina de pez cebra adultos

Many devastating inherited eye diseases result in progressive and irreversible blindness because humans cannot regenerate dying or diseased retinal ...

Trajectory Data Analyses for Pedestrian Space-time Activity Study

It is well recognized that human movement in the spatial and temporal dimensions has direct influence on disease transmission1-3. An infectious disease typically spreads via contact between infected and susceptible individuals in their overlapped activity spaces. Therefore, daily mobility-activity information can be used as an indicator to measure exposures to risk factors of infection. However, a major difficulty and thus the reason for paucity of studies of infectious disease transmission at the micro scale arise from the lack of detailed individual mobility data. Previously in transportation and tourism research detailed space-time activity data often relied on the time-space diary technique, which requires subjects to actively record their activities in time and space. This is highly demanding for the participants and collaboration from the participants greatly affects the quality of data4.
Modern technologies such as GPS and mobile communications have made possible the automatic collection of trajectory data. The data collected, however, is not ideal for modeling human space-time activities, limited by the accuracies of existing devices. There is also no readily available tool for efficient processing of the data for human behavior study. We present here a suite of methods and an integrated ArcGIS desktop-based visual interface for the pre-processing and spatiotemporal analyses of trajectory data. We provide examples of how such processing may be used to model human space-time activities, especially with error-rich pedestrian trajectory data, that could be useful in public health studies such as infectious disease transmission modeling.
The procedure presented includes pre-processing, trajectory segmentation, activity space characterization, density estimation and visualization, and a few other exploratory analysis methods. Pre-processing is the cleaning of noisy raw trajectory data. We introduce an interactive visual pre-processing interface as well as an automatic module. Trajectory segmentation5 involves the identification of indoor and outdoor parts from pre-processed space-time tracks. Again, both interactive visual segmentation and automatic segmentation are supported. Segmented space-time tracks are then analyzed to derive characteristics of one's activity space such as activity radius etc. Density estimation and visualization are used to examine large amount of trajectory data to model hot spots and interactions. We demonstrate both density surface mapping6 and density volume rendering7. We also include a couple of other exploratory data analyses (EDA) and visualizations tools, such as Google Earth animation support and connection analysis. The suite of analytical as well as visual methods presented in this paper may be applied to any trajectory data for space-time activity studies.

A suite of spatiotemporal processing methods are presented to analyze human trajectory data, such as that collected using a GPS device, for the purpose of modeling pedestrian space-time activities.

Los análisis de trayectoria de datos para el estudio de peatones Actividad espacio-tiempo

It is well recognized that human movement in the  spatial and temporal dimensions has direct influence on disease transmission1-3.  An infectious disease ...

Metabolic Labeling and Membrane Fractionation for Comparative Proteomic Analysis of Arabidopsis thaliana Suspension Cell Cultures

Plasma membrane microdomains are features based on the physical properties of the lipid and sterol environment and have particular roles in signaling processes. Extracting sterol-enriched membrane microdomains from plant cells for proteomic analysis is a difficult task mainly due to multiple preparation steps and sources for contaminations from other cellular compartments. The plasma membrane constitutes only about 5-20% of all the membranes in a plant cell, and therefore isolation of highly purified plasma membrane fraction is challenging. A frequently used method involves aqueous two-phase partitioning in polyethylene glycol and dextran, which yields plasma membrane vesicles with a purity of 95% 1. Sterol-rich membrane microdomains within the plasma membrane are insoluble upon treatment with cold nonionic detergents at alkaline pH. This detergent-resistant membrane fraction can be separated from the bulk plasma membrane by ultracentrifugation in a sucrose gradient 2. Subsequently, proteins can be extracted from the low density band of the sucrose gradient by methanol/chloroform precipitation. Extracted protein will then be trypsin digested, desalted and finally analyzed by LC-MS/MS. Our extraction protocol for sterol-rich microdomains is optimized for the preparation of clean detergent-resistant membrane fractions from Arabidopsis thaliana cell cultures.
We use full metabolic labeling of Arabidopsis thaliana suspension cell cultures with K15NO3 as the only nitrogen source for quantitative comparative proteomic studies following biological treatment of interest 3. By mixing equal ratios of labeled and unlabeled cell cultures for joint protein extraction the influence of preparation steps on final quantitative result is kept at a minimum. Also loss of material during extraction will affect both control and treatment samples in the same way, and therefore the ratio of light and heave peptide will remain constant. In the proposed method either labeled or unlabeled cell culture undergoes a biological treatment, while the other serves as control 4.

Metabolic Labeling and Membrane Fractionation for Comparative Proteomic Analysis of Arabidopsis thaliana Suspension Cell Cultures

Here we describe a robust method for the fractionation of plant plasma membranes into detergent resistant and detergent soluble membranes based on a mixture of unlabeled and in vivo fully 15N labeled Arabidopsis thaliana cell cultures. The procedure is applied for comparative proteomic studies to understand signaling processes.

Metabólicas etiquetado y de membrana de fraccionamiento para Comparativo Proteómica Análisis de<em&gt; Arabidopsis thaliana</em&gt; Culturas suspensión celular

Plasma membrane microdomains are features based on the physical properties of the lipid and sterol environment and have particular roles in signaling ...