Los autores desean agradecer al Dr. Sheng Ding, del Instituto Scripps de Investigación y el Dr. Deng Hongkui de la Universidad de Pekín por su ayuda y dirección.

1. Preparación de las placas de alimentación MEF <ol><li> Un día antes de que el cultivo de células madre embrionarias, descongele un vial de irradiados E14.5 CF-1 células alimentadoras MEF (ver nuestro procedimiento sobre la forma de descongelar las células ES). </li><li> Placa de las células de alimentación MEF, con una densidad de 10.000 células / pocillo en una placa de 12 también. Se incuban las células durante la noche a 37 ° C y 5% CO 2. MEF celular medios de comunicación: DMEM suplementado con 10% ES-PBS, la glutamina 1X y 1X no aminoácidos esenciales. </li></ol> 2. Mantenimiento de auto-renovación de las células madre embrionarias de ratón <ol><li> Separar las células madre embrionarias con tripsina. Sembrar las células a una densidad de 50.000 células / pocillo en las placas de alimentación preparada previamente MEF en medios de cultivo (MEM golpe de gracia complementado con un 15% KSR, 4 mM L-glutamina, 0,1 mM no aminoácidos esenciales y BME 1X), complementado con SC1 a la concentración deseada (en el ejemplo 100 nm, 300 nm, y M 1). También hemos añadido un control positivo, así que fue complementado con 1000 μ / ml de LIF. Se incuban las células durante la noche a 37 ° C y 5% CO 2. </li><li> Cultivo de las células a 37 ° C y 5% de CO 2 durante 3-4 días en cada paso. Actualizar los medios de comunicación cada 48 horas. </li><li> Células paso 1:10-1:15 con tripsina para mantener una densidad similar a la densidad de siembra inicial. Después de cinco pasajes, las células pueden ser examinados para la expresión de marcadores de pluripotencia típicos utilizando inmunocitoquímica. </li></ol> 3. El examen de inmuno marcadores de pluripotencia <ol><li> Lave suavemente las células tres veces con PBS. </li><li> Fijar las células con 500 l de solución fijadora durante 20 minutos a temperatura ambiente. </li><li> Lave suavemente las células tres veces con PBS. </li><li> Bloquear la unión no específica con 500 l de amortiguación de bloqueo durante una hora a temperatura ambiente. </li><li> Se incuban las células con 250 l de la primaria de anticuerpos específicos (en el ejemplo Nanog, Sox2, SSEA1 y Oct4 en las siguientes diluciones: 1:500, 1:2000, 1:500 y 1:500) </li><li> Lave suavemente las células tres veces con PBS. </li><li> Se incuban las células con 250 l de anticuerpo secundario durante dos horas a temperatura ambiente, manteniéndose alejado de la luz (en el ejemplo burro anti-ratón conjugado con Alexa Fluor ® 555 a 1:2000 y burro anti-conejo conjugado con Alexa Fluor ® 488 a 1 : 2000). </li><li> Lave suavemente las células tres veces con PBS. </li><li> Añadir DAPI (concentración final de 1 mg / ml) para el último lavado e incubar 5 minutos para visualizar los núcleos. </li><li> Analizar las células bajo un microscopio de fluorescencia. </li></ol> 4. Los resultados representativos: 1. Resultados de la morfología: Células madre embrionarias de ratón (ESC R1) fueron cultivadas en células alimentadoras MEF en la presencia de cualquiera de LIF o SC1 para mantener la auto-renovación en un estado indiferenciado. Después del segundo paso, la diferenciación se puede observar en las células sin LIF o SC1 (control negativo) y después de 5 pasajes prácticamente no se observaron colonias indiferenciadas. LIF (control positivo) colonias tratadas se mantuvo en un estado indiferenciado de los 5 pases celulares. Las células tratadas con SC1 a concentraciones de 300 nm o 100 también se mantuvo diferenciado después de 5 pasajes, sin embargo, las células tratadas con 1 mM SC1 muerte celular experimentado tras el paso cuarto. (Fig 2 de la nota de aplicación) La Tabla 1 resume las observaciones morfológicas. 2. Expresión de marcadores de pluripotencia Células ES de ratón mantuvo durante 5 pasajes fueron fijados y examinados por inmunohistoquímica para SSEA1, Oct4, Sox2 y Nanog. Expresión de los marcadores fue similar a las células mantenidas en LIF. (Fig 3 y 4 de la nota de aplicación) <img src="/files/ftp_upload/1550/1550fig2a.jpg" alt="Figura 1" /> Figura 1: Comparación de Morfología de las células mantenidas en LIF o SC1. No se observaron diferencias en la morfología se observó. <img src="/files/ftp_upload/1550/1550fig2c.jpg" alt="Figura 2 y 3" /> Figura 2 y Figura 3: Nanog, SSEA1, Sox2, Oct4 y la tinción de células madre embrionarias mantiene con SC1 o LIF (fig 4 de la nota de aplicación). Células mantenidas en SC1 mostrar expresión similar marcador de pluripotencia de las células mantenidas en LIF. Tabla 1 <table border="1" cellspacing="0" cellpadding="0"><tbody><tr><td></td><td> Control Negativo </td><td> LIF control positivo </td><td> SC1 1um </td><td> SC1 300 nM </td><td> SC1 100 nM </td></tr><tr><td> Primero paso </td><td> ES normal de la morfología celular </td><td> ES normal de la morfología celular </td><td> ES normal de la morfología celular </td><td> ES normal de la morfología celular </td><td> ES normal de la morfología celular </td></tr><tr><td> El paso segundo </td><td> Algunos morfología diferenciada </td><td> E normalesS morfología de las células </td><td> ES normal de la morfología celular </td><td> ES normal de la morfología celular </td><td> ES normal de la morfología celular </td></tr><tr><td> El paso tercero </td><td> La mayoría de las células diferenciadas </td><td> ES normal de la morfología celular </td><td> ES normal de la morfología celular </td><td> ES normal de la morfología celular </td><td> ES normal de la morfología celular </td></tr><tr><td> Paso cuarto </td><td> No colonias CES </td><td> ES normal de la morfología celular </td><td> La muerte celular observada </td><td> ES normal de la morfología celular </td><td> ES normal de la morfología celular </td></tr><tr><td> Pasaje quinto </td><td> diferenciado </td><td> ES normal de la morfología celular </td><td> La muerte celular observada </td><td> ES normal de la morfología celular </td><td> ES normal de la morfología celular </td></tr></tbody></table>

<ol>
	<li>Williams, R. L., Hilton, D. J., Pease, S., Willson, T. A., Stewart, C. L., Gearing, D. P., Wagner, E. F., Metcalf, D., Nicola, N. A., Gough, N. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Myeloid+leukaemia+inhibitory+factor+maintains+the+developmental+potential+of+embryonic+stem+cells.">Myeloid leukaemia inhibitory factor maintains the developmental potential of embryonic stem cells.</a> Nature. 336, 684-687 (1988).</li><li>Ying, Q. L., Wray, J., Nichols, J., Batlle-Morera, L., Doble, B., Woodgett, J., Cohen, P., Smith, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+ground+state+of+embryonic+stem+cell+self-renewal.">The ground state of embryonic stem cell self-renewal.</a> Nature. 453, 519-523 (2008).</li><li>Chen, S., Do, J. T., Zhang, Q., Yao, S., Yan, F., Peters, E. C., Scholer, H. R., Schultz, P. G., Ding, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Self-renewal+of+embryonic+stem+cells+by+a+small+molecule.">Self-renewal of embryonic stem cells by a small molecule.</a> Proc. Natl. Acat. Sci. USA. 103, 17266-17271 (2006).</li></ol>

The authors of this article are employed by Stemgent that produces reagents and instruments used in this article.

El SC1 pequeñas moléculas se pueden utilizar para mantener la auto-renovación, con un estado indiferenciado de las células madre embrionarias de ratón. Antes de utilizar en una línea celular no probado, sin embargo, deben ser valorados para determinar la concentración óptima. Por ejemplo, hemos probado tres concentraciones en el ratón de células ES R1 línea ESC. 100 nm y 300 nm concentraciones fueron capaces de sostener células ES de ratón, sin embargo, una concentración de 1 M era tóxico. SC1 también se puede utilizar bajo condiciones de alimentación libre.

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<td>SSEA-1 antibody</td>
<td>&nbsp;</td>
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<td>Nanog antibody</td>
<td>&nbsp;</td>
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the use of sc1 (pluripotin) to support mesc self-renewal in the absence of lif

Madre embrionarias de ratón (ES) las células son cultivadas convencionalmente con factor inhibidor de leucemia (LIF) para mantener la auto-renovación.<sup&gt; 1</sup&gt; Sin embargo, LIF es caro y la activación de la vía LIF/JAK/STAT3 no es absolutamente necesario para mantener el estado de auto-renovación.<sup&gt; 2</sup&gt; La molécula pequeña SC1 puede ser una alternativa económica a LIF. SC1 funciones a través de la inhibición dual de Ras-GAP y ERK1.<sup&gt; 3</supIlustración&gt; de su mecanismo de acción hace que sea una herramienta útil para estudiar el mecanismo molecular fundamental de la auto-renovación. Aquí se demuestra el procedimiento para el cultivo de células madre embrionarias de ratón en presencia de SC1 y demostrar que son capaces de mantener la auto-renovación en la ausencia de LIF. Las células cultivadas con SC1 mostró morfología similar en comparación con las células mantenidas con LIF. Ambos mostraron una morfología típica madre embrionarias de ratón después de cinco pasajes. Típica expresión de marcadores de pluripotencia (Oct4, Sox2, Nanog, y SSEA1) se observó después de cinco pasajes de la presencia de SC1. Además, SC1 no causó toxicidad manifiesta en las células madre embrionarias de ratón.

Watch this Scientific Journal Video about The use of SC1 Pluripotin to Support mESC Self-renewal in the Absence of LIF at JoVE.com

The use of SC1 Pluripotin to Support mESC Self-renewal in the Absence of LIF

SC1 funciones a través de la inhibición dual de Ras-GAP y ERK1. Pusimos a prueba la función de SC1 en el apoyo de células ES de ratón de auto-renovación en la ausencia de LIF y demostró que SC1 es capaz de mantener la auto-renovación de los cultivos celulares de ratón ES.

El uso de SC1 (Pluripotin) para apoyar MESC auto-renovación en la ausencia de LIF

Mouse embryonic stem (ES) cells are conventionally cultured with Leukemia Inhibitory Factor (LIF) to maintain self-renewal.1 However, LIF is expensive and ...

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Biology

The use of SC1 (Pluripotin) to Support mESC Self-renewal in the Absence of LIF

10.4K vistas.  Stemgent. SC1 funciones a través de la inhibición dual de Ras-GAP y ERK1. Pusimos a prueba la función de SC1 en el apoyo de células ES de ratón de auto-renovación en la ausencia de LIF y demostró que SC1 es capaz de mantener la auto-renovación de los cultivos celulares de ratón ES.

Video: The use of SC1 Pluripotin to Support mESC Self-renewal in the Absence of LIF

Use of the Protease Fluorescent Detection Kit to Determine Protease Activity

The Protease Fluorescent Detection Kit provides ready-to-use reagents for detecting the presence of protease activity. This simple assay to detect protease activity uses casein labeled with fluorescein isothiocyanate (FITC) as the substrate.
Protease activity results in the cleavage of the FITC-labeled casein substrate into smaller fragments, which do not precipitate under acidic conditions. After incubation of the protease sample and substrate, the reaction is acidified with the addition of trichloroacetic acid (TCA). The mixture is then centrifuged with the undigested substrate forming a pellet and the smaller, acid soluble fragments remaining in solution. The supernatant is neutralized and the fluorescence of the FITC-labeled fragments is measured.
The described kit procedure detects the trypsin protease control at a concentration of approximately 0.5 &mu;g/ml (5 ng of trypsin added to the assay). This sensitivity can be increased with a longer incubation time, up to 24 hours. The assay is performed in microcentrifuge tubes and procedures are provided for fluorescence detection using either cuvettes or multiwell plates.

The Protease Fluorescent Detection Kit is designed for the measurement of protease activity using fluorometry. It is also suitable for detection of trace amounts of protease contamination. The method is based on the proteolytic hydroysis of a proprietary formulation of a FITC-labeled casein substrate.

El uso del kit de la proteasa detección fluorescente para determinar la actividad de la proteasa

The Protease Fluorescent Detection Kit provides ready-to-use reagents for detecting the presence of protease activity. This simple assay to detect ...

Investigación

Biología

The use of Biofeedback in Clinical Virtual Reality: The INTREPID Project

Generalized anxiety disorder (GAD) is a psychiatric disorder characterized by a constant and unspecific anxiety that interferes with daily-life activities. Its high prevalence in general population and the severe limitations it causes, point out the necessity to find new efficient strategies to treat it. Together with the cognitive-behavioral treatments, relaxation represents a useful approach for the treatment of GAD, but it has the limitation that it is hard to be learned. The INTREPID project is aimed to implement a new instrument to treat anxiety-related disorders and to test its clinical efficacy in reducing anxiety-related symptoms. The innovation of this approach is the combination of virtual reality and biofeedback, so that the first one is directly modified by the output of the second one. In this way, the patient is made aware of his or her reactions through the modification of some features of the VR environment in real time. Using mental exercises the patient learns to control these physiological parameters and using the feedback provided by the virtual environment is able to gauge his or her success. The supplemental use of portable devices, such as PDA or smart-phones, allows the patient to perform at home, individually and autonomously, the same exercises experienced in therapist's office. The goal is to anchor the learned protocol in a real life context, so enhancing the patients' ability to deal with their symptoms. The expected result is a better and faster learning of relaxation techniques, and thus an increased effectiveness of the treatment if compared with traditional clinical protocols.

The Project on Virtual Reality Intelligent Multi-sensor System for the Treatment of Anxiety-related Disorders (INTREPID) is aimed at developing a multi-sensor context-aware virtual reality system for the treatment of anxiety-related disorders.

El uso de la biorretroalimentación en Realidad Virtual Clínica: El Proyecto de INTREPID

Generalized anxiety disorder (GAD) is a psychiatric disorder characterized by a constant and unspecific anxiety that interferes with daily-life ...

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.

La cuantificación de γH2AX focos en respuesta a la radiación ionizante

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

Oct4GiP Reporter Assay to Study Genes that Regulate Mouse Embryonic Stem Cell Maintenance and Self-renewal

Pluripotency and self-renewal are two defining characteristics of embryonic stem cells (ES cells). Understanding the underlying molecular mechanism will greatly facilitate the use of ES cells for developmental biology studies, disease modeling, drug discovery, and regenerative medicine (reviewed in 1,2).
To expedite the identification and characterization of novel regulators of ES cell maintenance and self-renewal, we developed a fluorescence reporter-based assay to quantitatively measure the self-renewal status in mouse ES cells using the Oct4GiP cells 3. The Oct4GiP cells express the green fluorescent protein (GFP) under the control of the Oct4 gene promoter region 4,5. Oct4 is required for ES cell self-renewal, and is highly expressed in ES cells and quickly down-regulated during differentiation 6,7. As a result, GFP expression and fluorescence in the reporter cells correlates faithfully with the ES cell identity 5, and fluorescence-activated cell sorting (FACS) analysis can be used to closely monitor the self-renewal status of the cells at the single cell level 3,8.
Coupled with RNAi, the Oct4GiP reporter assay can be used to quickly identify and study regulators of ES cell maintenance and self-renewal 3,8. Compared to other methods for assaying self-renewal, it is more convenient, sensitive, quantitative, and of lower cost. It can be carried out in 96- or 384-well plates for large-scale studies such as high-throughput screens or genetic epistasis analysis. Finally, by using other lineage-specific reporter ES cell lines, the assay we describe here can also be modified to study fate specification during ES cell differentiation.

We describe a fluorescence reporter assay to quickly identify and characterize genes that regulate mouse embryonic stem cell maintenance and self-renewal.

Oct4GiP reportero de ensayo para estudiar los genes que regulan la de embriones de ratón con células madre de mantenimiento y auto-renovación

Pluripotency and self-renewal are two defining characteristics of embryonic stem cells (ES cells). Understanding the underlying molecular mechanism will ...

The Use of Chemostats in Microbial Systems Biology

Cells regulate their rate of growth in response to signals from the external world. As the cell grows, diverse cellular processes must be coordinated including macromolecular synthesis, metabolism and ultimately, commitment to the cell division cycle. The chemostat, a method of experimentally controlling cell growth rate, provides a powerful means of systematically studying how growth rate impacts cellular processes - including gene expression and metabolism - and the regulatory networks that control the rate of cell growth. When maintained for hundreds of generations chemostats can be used to study adaptive evolution of microbes in environmental conditions that limit cell growth. We describe the principle of chemostat cultures, demonstrate their operation and provide examples of their various applications. Following a period of disuse after their introduction in the middle of the twentieth century, the convergence of genome-scale methodologies with a renewed interest in the regulation of cell growth and the molecular basis of adaptive evolution is stimulating a renaissance in the use of chemostats in biological research.

Cell growth rate is a regulated process and a primary determinant of cell physiology. Continuous culturing using chemostats enables extrinsic control of cell growth rate by nutrient limitation facilitating the study of molecular networks that control cell growth and how those networks evolve to optimize cell growth.

El uso de quimiostatos en Microbiana Biología de Sistemas

Cells regulate their rate of growth in response to signals from the external world. As the cell grows, diverse cellular processes must be coordinated ...

Identification of Key Factors Regulating Self-renewal and Differentiation in EML Hematopoietic Precursor Cells by RNA-sequencing Analysis

Hematopoietic stem cells (HSCs) are used clinically for transplantation treatment to rebuild a patient&#39;s hematopoietic system in many diseases such as leukemia and lymphoma. Elucidating the mechanisms controlling HSCs self-renewal and differentiation is important for application of HSCs for research and clinical uses. However, it is not possible to obtain large quantity of HSCs due to their inability to proliferate in vitro. To overcome this hurdle, we used a mouse bone marrow derived cell line, the EML (Erythroid, Myeloid, and Lymphocytic) cell line, as a model system for this study.
RNA-sequencing (RNA-Seq) has been increasingly used to replace microarray for gene expression studies. We report here a detailed method of using RNA-Seq technology to investigate the potential key factors in regulation of EML cell self-renewal and differentiation. The protocol provided in this paper is divided into three parts. The first part explains how to culture EML cells and separate Lin-CD34+ and Lin-CD34- cells. The second part of the protocol offers detailed procedures for total RNA preparation and the subsequent library construction for high-throughput sequencing. The last part describes the method for RNA-Seq data analysis and explains how to use the data to identify differentially expressed transcription factors between Lin-CD34+ and Lin-CD34- cells. The most significantly differentially expressed transcription factors were identified to be the potential key regulators controlling EML cell self-renewal and differentiation. In the discussion section of this paper, we highlight the key steps for successful performance of this experiment.
In summary, this paper offers a method of using RNA-Seq technology to identify potential regulators of self-renewal and differentiation in EML cells. The key factors identified are subjected to downstream functional analysis in vitro and in vivo.

RNA-sequencing and bioinformatics analyses were used to identify significantly and differentially expressed transcription factors in Lin-CD34+ and Lin-CD34- subpopulations of mouse EMLcells. These transcription factors might play important roles in determining the switch between self-renewing Lin-CD34+ and partially differentiated Lin-CD34- cells.

Identificación de los factores clave que regula la auto-renovación y diferenciación de las células precursoras hematopoyéticas EML por análisis de secuenciación de ARN-

Hematopoietic stem cells (HSCs) are used clinically for transplantation treatment to rebuild a patient&#39;s hematopoietic system in many diseases such as ...

Use of Enzymatic Biosensors to Quantify Endogenous ATP or H2O2 in the Kidney

Enzymatic microelectrode biosensors have been widely used to measure extracellular signaling in real-time. Most of their use has been limited to brain slices and neuronal cell cultures. Recently, this technology has been applied to the whole organs. Advances in sensor design have made &#160;possible the measuring of&#160;cell signaling in blood-perfused in vivo kidneys. The present protocols list the steps needed to measure ATP and H2O2 signaling in the rat kidney interstitium. Two separate sensor designs are used for the ex vivo and in vivo protocols. Both types of sensor&#160;are coated with&#160;a thin enzymatic biolayer on top of a permselectivity layer to give fast responding, sensitive and selective biosensors. The permselectivity layer protects the signal from the interferents in biological tissue, and the enzymatic layer utilizes&#160;the sequential catalytic reaction of glycerol kinase and glycerol-3-phosphate oxidase in the presence of ATP to produce H2O2. The set of sensors used for the ex vivo studies further detected analyte by oxidation of H2O2 on a platinum/iridium (Pt-Ir) wire electrode. The sensors for the&#160;in vivo studies are instead based on the reduction of H2O2 on a mediator coated gold electrode designed for blood-perfused tissue. Final concentration changes&#160;are detected by real-time amperometry followed by calibration to known concentrations of analyte. Additionally, the specificity of the amperometric signal can be confirmed by the addition of enzymes such as catalase and apyrase that break down H2O2 and ATP correspondingly. These sensors also rely heavily on accurate calibrations before and after each experiment. The following two protocols establish the study of real-time detection of ATP and H2O2 in kidney tissues, and can be further modified to extend the described method for use in other biological preparations or whole organs.

Use of Enzymatic Biosensors to Quantify Endogenous ATP or H2O2 in the Kidney

Enzymatic microelectrode biosensors enable real-time measurements of extracellular cell signaling in biologically-relevant concentrations. The following protocols extend the applications of biosensors to the ex vivo and in vivo detection of ATP and H2O2 in the kidney.

El uso de biosensores para cuantificar enzimática endógena ATP o H<sub&gt; 2</sub&gt; O<sub&gt; 2</sub&gt; En el riñón

Enzymatic microelectrode biosensors have been widely used to measure extracellular signaling in real-time. Most of their use has been limited to brain ...

Use of the Ramsay Assay to Measure Fluid Secretion and Ion Flux Rates in the Drosophila melanogaster Malpighian Tubule

Modulation of renal epithelial ion transport allows organisms to maintain ionic and osmotic homeostasis in the face of varying external conditions. The Drosophila&#160;melanogaster Malpighian (renal) tubule offers an unparalleled opportunity to study the molecular mechanisms of epithelial ion transport, due to the powerful genetics of this organism and the accessibility of its renal tubules to physiological study. Here, we describe the use of the Ramsay assay to measure fluid secretion rates from isolated fly renal tubules, with the use of ion-specific electrodes to measure sodium and potassium concentrations in the secreted fluid. This assay allows study of transepithelial fluid and ion fluxes of ~20 tubules at a time, without the need to transfer the secreted fluid to a separate apparatus to measure ion concentrations. Genetically distinct tubules can be analyzed to assess the role of specific genes in transport processes. Additionally, the bathing saline can be modified to examine the effects of its chemical characteristics, or drugs or hormones added. In summary, this technique allows the molecular characterization of basic mechanisms of epithelial ion transport in the Drosophila tubule, as well as regulation of these transport mechanisms.

Use of the Ramsay Assay to Measure Fluid Secretion and Ion Flux Rates in the Drosophila melanogaster Malpighian Tubule

This protocol describes the use of the Ramsay assay to measure fluid secretion rates from isolated Malpighian (renal) tubules from Drosophila melanogaster. In addition, the use of ion-specific electrodes to measure sodium and potassium concentrations in the secreted fluid, allowing calculation of transepithelial ion flux, is described.

El uso del ensayo de Ramsay medir la secreción de fluidos y de iones Flux tarifas en el<em&gt; Drosophila melanogaster</em&gt; Túbulo de Malpighi

Modulation of renal epithelial ion transport allows organisms to maintain ionic and osmotic homeostasis in the face of varying external conditions. The ...

Development of an Insert Co-culture System of Two Cellular Types in the Absence of Cell-Cell Contact

The role of secreted soluble factors in the modification of cellular responses is a recurrent theme in the study of all tissues and systems. In an attempt to make straightforward the very complex relationships between the several cellular subtypes that compose multicellular organisms, in vitro techniques have been developed to help researchers acquire a detailed understanding of single cell populations. One of these techniques uses inserts with a permeable membrane allowing secreted soluble factors to diffuse. Thus, a population of cells grown in inserts can be co-cultured in a well or dish containing a different cell type for evaluating cellular changes following paracrine signaling in the absence of cell-cell contact. Such insert co-culture systems offer various advantages over other co-culture techniques, namely bidirectional signaling, conserved cell polarity and population-specific detection of cellular changes. In addition to being utilized in the field of inflammation, cancer, angiogenesis and differentiation, these co-culture systems are of prime importance in the study of the intricate relationships that exist between the different cellular subtypes present in the central nervous system, particularly in the context of neuroinflammation. This article offers general methodological guidelines in order to set up an experiment in order to evaluating cellular changes mediated by secreted soluble factors using an insert co-culture system. Moreover, a specific protocol to measure the neuroinflammatory effects of cytokines secreted by lipopolysaccharide-activated N9 microglia on neuronal PC12 cells will be detailed, offering a concrete understanding of insert co-culture methodology.

In multicellular organisms, secreted soluble factors elicit responses from different cell types as a result of paracrine signaling. Insert co-culture systems offer a simple way to assess the changes mediated by secreted soluble factors in the absence of cell-cell contact.

Desarrollo de un Sistema de inserción Co-cultivo de dos tipos celulares en ausencia de la célula-célula Contacto

The role of secreted soluble factors in the modification of cellular responses is a recurrent theme in the study of all tissues and systems. In an attempt ...

The Use of Ex Vivo Whole-organ Imaging and Quantitative Tissue Histology to Determine the Bio-distribution of Fluorescently Labeled Molecules

Fluorescent labeling is a well-established process for examining the fate of labeled molecules under a variety of experimental conditions both in vitro and in vivo. Fluorescent probes are particularly useful in determining the bio-distribution of administered large molecules, where the addition of a small-molecule fluorescent label is unlikely to affect the kinetics or bio-distribution of the compound. A variety of methods exist to examine bio-distribution that vary significantly in the amount of effort required and whether the resulting measurements are fully quantitative, but using multiple methods in conjunction can provide a rapid and effective system for analyzing bio-distributions.
Ex vivo whole-organ imaging is a method that can be used to quickly compare the relative concentrations of fluorescent molecules within tissues and between multiple types of tissues or treatment groups. Using an imaging platform designed for live-animal or whole-organ imaging, fluorescence within intact tissues can be determined without further processing, saving time and labor while providing an accurate picture of the overall bio-distribution. This process is ideal in experiments attempting to determine the tissue specificity of a compound or for the comparison of multiple different compounds. Quantitative tissue histology on the other hand requires extensive further processing of tissues in order to create a quantitative measure of the labeled compounds. To accurately assess bio-distribution, all tissues of interest must be sliced, scanned, and analyzed relative to standard curves in order to make comparisons between tissues or groups. Quantitative tissue histology is the gold standard for determining absolute compound concentrations within tissues.
Here, we describe how both methods can be used together effectively to assess the ability of different administration methods and compound modifications to target and deliver fluorescently labeled molecules to the central nervous system1.

The Use of Ex Vivo Whole-organ Imaging and Quantitative Tissue Histology to Determine the Bio-distribution of Fluorescently Labeled Molecules

Ex vivo whole-organ imaging is a rapid method for determining the relative concentrations of fluorescently labeled compounds within and between tissues or treatment groups. Conversely, quantitative fluorescence histology, while more labor intensive, allows for the quantification of the absolute tissue levels of labeled molecules.

El uso de<em&gt; Ex Vivo</em&gt; Imaging entero de órganos y de tejidos Histología cuantitativa para determinar la bio-distribución de las moléculas marcadas con fluorescencia

Fluorescent labeling is a well-established process for examining the fate of labeled molecules under a variety of experimental conditions both in vitro ...