Este trabajo fue apoyado por subvenciones del Servicio Nacional de YW.CF (AG21068, AG31086).

1. La insulina preparación de la solución <ol><li> Prepare una solución fresca insulina bovina mediante la disolución de la insulina en PBS para alcanzar la concentración de 0,01 mg / ml. Tanto la insulina / PBS PBS y soluciones de control deben ser mantenidos en hielo durante todo el procedimiento de inyección. Estas soluciones deben prepararse con 0,5% (v / v) FD &amp; C Azul no. Un colorante de alimentos. </li></ol> 2. Aguja de preparación y la inyección Puesta en marcha <ol><li> Prepare agujas capilares de vidrio utilizando una micropipeta puller.The siguientes ajustes extractor producir agujas de calidad suficiente para la inyección: Heat, 345; Pull, 210; velocidad, 100; Tiempo, 200 (100 ms). Agujas recién sacó deben ser debilitados por presionando la punta a través de un tejido Kimwipe. Este proceso elimina el embotamiento de punta alargada de alta resistencia y produce una punta más gruesos con un diámetro de poro más grande. </li><li> Coloque las agujas punta roma en un tubo de microcentrífuga que contiene la insulina / PBS o solución de PBS. Capilar resultados de la acción en la parte trasera de llenado de cada aguja. Observe la punta de la aguja bajo un microscopio estereoscópico para asegurar que no queden burbujas de aire o restos aparecer en la punta. Deseche las agujas que no se llenen limpiamente. </li><li> Insertar las agujas se introducen en el porta-agujas manual de microinyector y la posición del titular de la aguja con un micromanipulador para que la punta de la aguja es visible a través de un microscopio estereoscópico. Aplique una presión positiva en la columna de líquido en la aguja girando el manual de perilla microinyector micrómetro unido al émbolo de la jeringa microinyector. </li><li> Verifique que la presión suficiente para el desplazamiento del fluido se ha aplicado al tocar un Kimwipe a la punta de la aguja y la confirmación de flujo de fluidos. </li><li> Una vez que la aguja ha sido preparado para la inyección, colocar una tabla de calibración para el eje de la aguja con cinta adhesiva transparente, y llevar la punta de la aguja en el foco a través de un microscopio estereoscópico con 20X. </li></ol> 3. Preparación volar <ol><li> Diez días de edad, las moscas hembras se utilizan para los experimentos de inyección. Recoger las moscas dentro de las 24 h de la eclosión. Anestesiar a las moscas con CO 2 humidificado en un cojín de gas, tipo de hombres y mujeres moscas a cabo en viales que contienen el patrón o la dieta para el tratamiento. Mantener las moscas hembras en dietas experimentales por 10 días. </li><li> En el décimo día después de la eclosión y la separación de las dietas experimentales, la transferencia de las moscas de sus alimentos que contienen los viales a los viales que contiene un tapón de 5 ml de 2% de agar y matarlos de hambre de 12 a 16 h. </li><li> Transferencia de las moscas de hambre viales que contienen 10% de filtros de la glucosa en remojo durante una hora antes de la inyección de insulina. </li><li> En pocas palabras anestesiar a las moscas con CO 2 humidificado glucosa después de comer y después inmovilizar frío en hielo. </li></ol> 4. Procedimiento de inyección <ol><li> Pellizque suavemente una mosca en frío inmovilizado con un par de pinzas finas y mantenerlo cerca de la punta de la aguja de modo que la punta es adyacente a la región anterior del lado izquierdo del tórax de la mosca. Llevar las dos de la punta de la aguja y el tórax de la mosca en el foco bajo el microscopio estereoscópico. </li><li> Suavemente mueva la marcha hacia la punta de la aguja de modo que la punta de la aguja toca el centro de la protuberancia de la región prescutum izquierda del tórax de la mosca (Fig. 1). Una vez que el vuelo esté debidamente orientados y alineados con la punta de la aguja, continuar avanzando en la marcha en la aguja de modo que la aguja empala el centro de la prescutum. </li><li> Aplicar presión positiva si es necesario mediante la mejora de émbolo de la jeringa con perilla micromanipulador la microinyector hasta 0,1 l de fluido se inyecta en la marcha. El flujo de líquido en hemocele de la mosca impartirá un color azul al lado izquierdo del tórax anterior. De vez en cuando hay que retirar y avanzar varias veces para desalojar cualquier obstrucción punta de la aguja y permitir el flujo de fluido. </li><li> Permitir moscas inyectadas a recuperarse en los viales de agar al 2% para los puntos de tiempo determinado antes de la extracción de hemolinfa. </li></ol> 5. Hemolinfa Colección <ol><li> En pocas palabras anestesiar las moscas con CO 2 humidificado en los puntos de tiempo deseado después de la inyección y la posición de cada vuelo dorsal-boca abajo en cinta de doble cara colocada en la superficie de una plataforma de CO 2. Organizar las moscas, incluso en las filas con cápsulas de la cabeza alineada. Se puede utilizar un aplicador de madera recortada para presionar por sus alas en la cinta adhesiva y asegurar la inmovilización. </li><li> Una vez que las moscas se fija a la cinta, sujete cada trompa mosca con unas pinzas finas y tire de él hacia la región ventral y posterior de la mosca de manera que la parte frontal de la cápsula de la cabeza es visible a través del microscopio estereoscópico. </li><li> Con la otra mano y mientras mantiene la trompa en su lugar, perfore el centro de la cápsula de la cabeza justo encima de la sutura ptilinal utilizando una aguja de tungsteno agudo (Fig. 2). Hay que tener cuidado de no insertar la aguja demasiado lejos ya que es fácil de perforar la punta de la aguja a través del otro lado de la cápsula de la cabeza y, posteriormente, perder control de flujo de hemolinfa. Punción todas las moscas en un grupo de la inyección antes de recoger la hemolinfa. </li><li> Una vez que la cápsula de la cabeza ha sido perforado, use un aplicador de madera recortada para aplicar suavemente presión sobre el abdomen de la mosca. Puede ser útil para rodar la marcha más de lo que se apoya en su parte ventral al aplicar presión. Este procedimiento produce una gota de hemolinfa en el sitio de punción cabeza cápsula. </li><li> Toque uno de los extremos de un tubo capilar se 1μl a la gota de hemolinfa emergentes del sitio de la punción cabeza cápsula. La hemolinfa se entre en el tubo a través de la acción capilar. Determinar y registrar la cantidad de hemolinfa recogidos por el control de la columna de líquido dentro del tubo capilar con una tabla de volumen se graduó. </li></ol> 6. Hemolinfa la determinación de glucosa <ol><li> Expulsión de las muestras de hemolinfa en pocillos de la microplaca con 100 l de reactivo de glucosa Infinity. Mantenga la placa de hielo durante la carga de las muestras de hemolinfa. </li><li> Establecer una curva estándar de carga por separado cada una l de soluciones de reserva de glucosa en 50 mM, 25 mm, 12,5 mm, y 6.25mM 3.125mM. </li><li> Incubar las muestras a 37 ° C durante 10 minutos. </li><li> Detectar la absorbancia a 340 nm. </li><li> Cuenta para el volumen de la hemolinfa recogidos y determinar la concentración de glucosa en la muestra sobre la base de la curva estándar con concentraciones de glucosa conocidos. </li></ol> 7. Resultados representante Una respuesta típica de tolerancia a la insulina se detecta en la insulina inyectada moscas cuando se detecta un descenso en los niveles circulantes de glucosa 15 minutos después de la inyección. Por el contrario, esa respuesta no se ve en las moscas de PBS inyectado (Fig. 3). Esta respuesta en la utilización de glucosa periférica continúa en la insulina inyectada vuela hasta 30 minutos después de la inyección. En forma rutinaria extraer 0.2-0.5 l de la hemolinfa por 4-5 moscas en cada grupo de la inyección. Tres grupos de inyección se incluyen en cada experimento. <img src="/files/ftp_upload/2722/2722fig1.jpg" alt="Figura 1"/> Figura 1. El lado izquierdo del tórax que muestra Drosophila sitio inserción de la aguja (Modificado de Demerec, 1950) 7. Insertar la aguja en el centro de la prescutum en la región anterior, dorsal del lado izquierdo del tórax. <img src="/files/ftp_upload/2722/2722fig2.jpg" alt="Figura 2"/> Figura 2. Vista frontal de la cabeza de Drosophila que muestra la ubicación de punción para la extracción de hemolinfa (Modificado de Demerec, 1950) 7. Perforar la cápsula de la cabeza con una sonda de tungsteno finamente afiladas en el centro de la cápsula de la cabeza justo encima de la sutura ptilinal. <img src="/files/ftp_upload/2722/2722fig3.jpg" alt="Figura 3"/> Figura 3. Una respuesta típica de tolerancia a la insulina detectada en el control de moscas adultas. Control de moscas w 1118 fueron inyectados con insulina bovina (1 ng en PBS) o PBS. Las moscas en los grupos de replicar fueron autorizados a recuperar los minutos 0, 15 ó 30 y niveles de glucosa circulante se midieron.

<ol>
	<li>Rulifson, E. J., Kim, S. K., 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=Ablation+of+insulin-producing+neurons+in+flies:+growth+and+diabetic+phenotypes.">Ablation of insulin-producing neurons in flies: growth and diabetic phenotypes.</a> Science. 296, 1118-1118 (2002).</li><li>Kim, S. K., Rulifson, E. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Conserved+mechanisms+of+glucose+sensing+and+regulation+by+Drosophila+corpora+cardiaca+cells.">Conserved mechanisms of glucose sensing and regulation by Drosophila corpora cardiaca cells.</a> Nature. 431, 316-316 (2004).</li><li>Broughton, S. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Longer+lifespan,+altered+metabolism,+and+stress+resistance+in+Drosophila+from+ablation+of+cells+making+insulin-like+ligands.">Longer lifespan, altered metabolism, and stress resistance in Drosophila from ablation of cells making insulin-like ligands.</a> Proc Natl Acad Sci U S A. 102, 3105-3105 (2005).</li><li>Haselton, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Partial+ablation+of+adult+Drosophila+insulin-producing+neurons+modulates+glucose+homeostasis+and+extends+life+span+without+insulin+resistance.">Partial ablation of adult Drosophila insulin-producing neurons modulates glucose homeostasis and extends life span without insulin resistance.</a> Cell Cycle. 9, 3063-3063 (2010).</li><li>Haselton, A. T., Fridell, Y. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Adult+Drosophila+melanogaster+as+a+model+for+the+study+of+glucose+homeostasis.">Adult Drosophila melanogaster as a model for the study of glucose homeostasis.</a> Aging (Albany NY). 2, 523-523 (2010).</li><li>Belgacem, Y. H., Martin, J. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Disruption+of+insulin+pathways+alters+trehalose+level+and+abolishes+sexual+dimorphism+in+locomotor+activity+in+Drosophila.">Disruption of insulin pathways alters trehalose level and abolishes sexual dimorphism in locomotor activity in Drosophila.</a> J Neurobiol. 66, 19-19 (2006).</li><li>Demerec, 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> Biology of Drosophila. , (1950).</li></ol>

La técnica descrita en este informe es potencialmente útil en cualquier estudio que investiga los procesos fisiológicos que resulta en alteraciones detectables en la composición de la hemolinfa de Drosophila. Mediante la combinación de la inyección y recolección de la hemolinfa de esta manera, es posible determinar los efectos inmediatos fisiológicamente relevantes de un determinado tratamiento experimental o manipulación. La principal ventaja de esta &quot;sangría&quot; técnica en la recolección de...

<table border="1"><tbody><tr><th> Nombre del reactivo / equipo </th><th> Empresa </th><th> Número de catálogo </th></tr><tr><td> Insulina bovina </td><td> Sigma </td><td> I5500 </td></tr><tr><td> Infinito reactivo de glucosa </td><td> Thermo Electron Corporation </td><td> TR1541 </td></tr><tr><td> Manual microinyector </td><td> Sutter Instrumento </td><td></td></tr><tr><td> P-87 Flamming / Brown micropipeta extractor </td><td> Sutter Instrumento </td><td></td></tr><tr><td> Un solo cuerpo de vidrio de borosilicato capilares </td><td> AM Sistemas </td><td> 626000 </td></tr><tr><td> FD &amp; C Azul N º 1 </td><td> McCormick &amp; Company </td><td></td></tr><tr><td> Un tubo capilar se l </td><td> Drummond </td><td></td></tr><tr><td> Tres ejes manual de micromanipulador y la base </td><td> Mundial de Instrumentos de Precisión </td><td></td></tr></tbody></table>

insulin injection and hemolymph extraction to measure insulin sensitivity in adult drosophila melanogaster

Conserva los mecanismos de detección de nutrientes existen entre los mamíferos y mosca de la fruta que se asemeja péptidos de mamíferos insulina y el glucagón, respectivamente, la función de mantener la homeostasis de la glucosa durante el desarrollo de 1,2 estadios larvarios. Los estudios sobre las moscas adultas en gran medida post-mitótico han puesto de manifiesto la perturbación de la homeostasis de la glucosa como resultado de la ablación genética de la insulina-like peptide (ILP) que producen las células (IPC) 3. Por lo tanto, las moscas adultas frutas son una gran promesa como un sistema modelo adecuado genética de los trastornos metabólicos como la diabetes tipo II. Para seguir desarrollando el sistema de mosca de la fruta, comparable pruebas fisiológicas para medir la tolerancia a la glucosa y la sensibilidad a la insulina en los mamíferos se debe establecer. Con este fin, recientemente se ha descrito un nuevo procedimiento para medir la respuesta de tolerancia oral a la glucosa en la mosca adulta y han demostrado la importancia de la IPC para adultos en el mantenimiento de la homeostasis de la glucosa 4,5. Aquí, se ha modificado el procedimiento descrito anteriormente para la inyección de insulina 6 y lo combinó con un método de extracción de hemolinfa novela para medir la sensibilidad periférica a la insulina en la mosca adulta. Excepcionalmente, el protocolo permite dirigir las mediciones fisiológicas de la capacidad de la mosca adulta de disponer de una carga de glucosa periférica tras la inyección de insulina, una metodología que hace que sea factible para caracterizar mutantes señalización de la insulina y las posibles intervenciones que afectan la tolerancia a la glucosa y la sensibilidad a la insulina en la mosca adulta.

Watch this Scientific Journal Video about Insulin Injection and Hemolymph Extraction to Measure Insulin Sensitivity in Adult Drosophila melanogaster at JoVE.com

Insulin Injection and Hemolymph Extraction to Measure Insulin Sensitivity in Adult Drosophila melanogaster

Señalización de la insulina conserva las vías se encuentran en la mosca de la fruta<em&gt; Drosophila melanogaster</em&gt; Hacer de este organismo una herramienta potencial para el modelado de los trastornos metabólicos como la diabetes tipo II. Con este fin, es fundamental para establecer pruebas fisiológicas para medir efectivamente la acción sistémica a la insulina en la utilización de glucosa periférica en la mosca adulta.

Inyección de insulina y extracción hemolinfa para medir la sensibilidad a la insulina en adultos Drosophila melanogaster</em

Conserved nutrient sensing mechanisms exist between mammal and fruit fly where peptides resembling mammalian insulin and glucagon, respectively function ...

insulin-injection-hemolymph-extraction-to-measure-insulin-sensitivity

Research

JoVE Journal

Biology

Insulin Injection and Hemolymph Extraction to Measure Insulin Sensitivity in Adult Drosophila melanogaster

19.6K vistas.  State University of New York. Señalización de la insulina conserva las vías se encuentran en la mosca de la fruta Drosophila melanogaster Hacer de este organismo una herramienta potencial para el modelado de los trastornos metabólicos como la diabetes tipo II. Con este fin, es fundamental para establecer pruebas fisiológicas para medir efectivamente la acción sistémica a la insulina en la utilización de glucosa periférica en la mosca adulta.

Video: Insulin Injection and Hemolymph Extraction to Measure Insulin Sensitivity in Adult Drosophila melanogaster

High-Resolution Video Tracking of Locomotion in Adult Drosophila Melanogaster

Flies provide an important model for studying complex behavior due to the plethora of genetic tools available to researchers in this field. Studying locomotor behavior in Drosophila melanogaster relies on the ability to be able to quantify changes in motion during or in response to a given task. For this reason, a high-resolution video tracking system, such as the one we describe in this paper, is a valuable tool for measuring locomotion in real-time. Our protocol involves the use of an initial air pulse to break the flies momentum, followed by a thirty second filming period in a square chamber. A tracking program is then used to calculate the instantaneous speed of each fly within the chamber in 10 msec increments. Analysis software then compiles this data, and outputs a variety of parameters such as average speed, max speed, time spent in motion, acceleration, etc. This protocol will discuss proper feeding and management of flies for behavioral tasks, handling flies without anesthetization or immobilization, setting up a controlled environment, and running the assay from start to finish.

The study of complex locomotor behavior in Drosophila melanogaster is dependent upon the ability to quantify changes in a given fly's movement. This article demonstrates how to do this using a high-resolution tracking system.

Vídeo de alta resolución de Seguimiento de la locomoción en adultos de Drosophila melanogaster

Flies provide an important model for studying complex behavior due to the plethora of genetic tools available to researchers in this field.  Studying ...

Investigación

Biología

Dissection of Oenocytes from Adult Drosophila melanogaster

In Drosophila melanogaster, as in other insects, a waxy layer on the outer surface of the cuticle, composed primarily of hydrocarbon compounds, provides protection against desiccation and other environmental challenges. Several of these cuticular hydrocarbon (CHC) compounds also function as semiochemical signals, and as such mediate pheromonal communications between members of the same species, or in some instances between different species, and influence behavior. Specialized cells referred to as oenocytes are regarded as the primary site for CHC synthesis. However, relatively little is known regarding the involvement of the oenocytes in the regulation of the biosynthetic, transport, and deposition pathways contributing to CHC output. Given the significant role that CHCs play in several aspects of insect biology, including chemical communication, desiccation resistance, and immunity, it is important to gain a greater understanding of the molecular and genetic regulation of CHC production within these specialized cells. The adult oenocytes of D. melanogaster are located within the abdominal integument, and are metamerically arrayed in ribbon-like clusters radiating along the inner cuticular surface of each abdominal segment. In this video article we demonstrate a dissection technique used for the preparation of oenocytes from adult D. melanogaster. Specifically, we provide a detailed step-by-step demonstration of (1) how to fillet prepare an adult Drosophila abdomen, (2) how to identify the oenocytes and discern them from other tissues, and (3) how to remove intact oenocyte clusters from the abdominal integument. A brief experimental illustration of how this preparation can be used to examine the expression of genes involved in hydrocarbon synthesis is included. The dissected preparation demonstrated herein will allow for the detailed molecular and genetic analysis of oenocyte function in the adult fruit fly.

Dissection of Oenocytes from Adult Drosophila melanogaster

In insects, the oenocytes produce cuticular hydrocarbon compounds. These compounds protect against desiccation and facilitate chemical communication. Here we demonstrate a dissection technique used to isolate the oenocytes from adult Drosophila melanogaster, and illustrate how this preparation can be utilized to study genes involved in hydrocarbon synthesis.

La disección de Oenocytes de Adultos Drosophila melanogaster</em

In Drosophila melanogaster, as in other insects, a waxy layer on the outer surface of the cuticle, composed primarily of hydrocarbon compounds, provides ...

A Quantitative Assay for Insulin-expressing Colony-forming Progenitors

The field of pancreatic stem and progenitor cell biology has been hampered by a lack of in vitro functional and quantitative assays that allow for the analysis of the single cell. Analyses of single progenitors are of critical importance because they provide definitive ways to unequivocally demonstrate the lineage potential of individual progenitors. Although methods have been devised to generate "pancreatospheres" in suspension culture from single cells, several limitations exist. First, it is time-consuming to perform single cell deposition for a large number of cells, which in turn commands large volumes of culture media and space. Second, numeration of the resulting pancreatospheres is labor-intensive, especially when the frequency of the pancreatosphere-initiating progenitors is low. Third, the pancreatosphere assay is not an efficient method to allow both the proliferation and differentiation of pancreatic progenitors in the same culture well, restricting the usefulness of the assay.
To overcome these limitations, a semi-solid media based colony assay for pancreatic progenitors has been developed and is presented in this report. This method takes advantage of an existing concept from the hematopoietic colony assay, in which methylcellulose is used to provide viscosity to the media, allowing the progenitor cells to stay in three-dimensional space as they undergo proliferation as well as differentiation. To enrich insulin-expressing colony-forming progenitors from a heterogeneous population, we utilized cells that express neurogenin (Ngn) 3, a pancreatic endocrine progenitor cell marker. Murine embryonic stem (ES) cell-derived Ngn3 expressing cells tagged with the enhanced green fluorescent protein reporter were sorted and as many as 25,000 cells per well were plated into low-attachment 24-well culture dishes. Each well contained 500 &mu;L of semi-solid media with the following major components: methylcellulose, Matrigel, nicotinamide, exendin-4, activin &beta;B, and conditioned media collected from murine ES cell-derived pancreatic-like cells. After 8 to 12 days of culture, insulin-expressing colonies with distinctive morphology were formed and could be further analyzed for pancreatic gene expression using quantitative RT-PCR and immunoflourescent staining to determine the lineage composition of each colony.
In summary, our colony assay allows easy detection and quantification of functional progenitors within a heterogeneous population of cells. In addition, the semi-solid media format allows uniform presentation of extracellular matrix components and growth factors to cells, enabling progenitors to proliferate and differentiate in vitro. This colony assay provides unique opportunities for mechanistic studies of pancreatic progenitor cells at the single cell level.

A three-dimensional clonogenic assay that allows pancreatic-like progenitors to differentiate into insulin-expressing colonies is described. This method takes advantage of semi-solid media containing methylcellulose, Matrigel and growth factors, in which single progenitors proliferate and differentiate in vitro, permitting quantification of the number of functional progenitors in a population.

Un análisis cuantitativo de la insulina que expresan la formación de colonias de progenitores

The field of pancreatic stem and progenitor cell biology has been hampered by a lack of in vitro functional and quantitative assays that allow for the ...

Measurement of Lifespan in Drosophila melanogaster

Aging is a phenomenon that results in steady physiological deterioration in nearly all organisms in which it has been examined, leading to reduced physical performance and increased risk of disease. Individual aging is manifest at the population level as an increase in age-dependent mortality, which is often measured in the laboratory by observing lifespan in large cohorts of age-matched individuals. Experiments that seek to quantify the extent to which genetic or environmental manipulations impact lifespan in simple model organisms have been remarkably successful for understanding the aspects of aging that are conserved across taxa and for inspiring new strategies for extending lifespan and preventing age-associated disease in mammals.
The vinegar fly, Drosophila melanogaster, is an attractive model organism for studying the mechanisms of aging due to its relatively short lifespan, convenient husbandry, and facile genetics. However, demographic measures of aging, including age-specific survival and mortality, are extraordinarily susceptible to even minor variations in experimental design and environment, and the maintenance of strict laboratory practices for the duration of aging experiments is required. These considerations, together with the need to practice careful control of genetic background, are essential for generating robust measurements. Indeed, there are many notable controversies surrounding inference from longevity experiments in yeast, worms, flies and mice that have been traced to environmental or genetic artifacts1-4. In this protocol, we describe a set of procedures that have been optimized over many years of measuring longevity in Drosophila using laboratory vials. We also describe the use of the dLife software, which was developed by our laboratory and is available for download (<a href="http://sitemaker.umich.edu/pletcherlab/software">http://sitemaker.umich.edu/pletcherlab/software</a>). dLife accelerates throughput and promotes good practices by incorporating optimal experimental design, simplifying fly handling and data collection, and standardizing data analysis. We will also discuss the many potential pitfalls in the design, collection, and interpretation of lifespan data, and we provide steps to avoid these dangers.

Measurement of Lifespan in Drosophila melanogaster

Drosophila melanogaster is a powerful model organism for exploring the molecular basis of longevity regulation. This protocol will discuss the steps involved in generating a reproducible, population-based measurement of longevity as well as potential pitfalls and how to avoid them.

Medición de la esperanza de vida en<em&gt; Drosophila melanogaster</em

Aging is a phenomenon that results in steady physiological deterioration in nearly all organisms in which it has been examined, leading to reduced ...

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 ...

Glucose Uptake Measurement and Response to Insulin Stimulation in In Vitro Cultured Human Primary Myotubes

Skeletal muscle is the largest glucose deposit in mammals and largely contributes to glucose homeostasis. Assessment of insulin sensitivity of muscle cells is of major relevance for all studies dedicated to exploring muscle glucose metabolism and characterizing metabolic alterations. In muscle cells, glucose transporter type 4 (GLUT4) proteins translocate to the plasma membrane in response to insulin, thus allowing massive entry of glucose into the cell. The ability of muscle cells to respond to insulin by increasing the rate of glucose uptake is one of the standard readouts to quantify muscle cell sensitivity to insulin. Human primary myotubes are a suitable in vitro model, as the cells maintain many features of the donor phenotype, including insulin sensitivity. This in vitro model is also suitable for the test of any compounds that could impact insulin responsiveness. Measurements of the glucose uptake rate in differentiated myotubes reflect insulin sensitivity.
In this method, human primary muscle cells are cultured in vitro to obtain differentiated myotubes, and glucose uptake rates with and without insulin stimulation are measured. We provide a detailed protocol to quantify passive and active glucose transport rates using radiolabeled [3H] 2-deoxy-D-Glucose ([3H]2dG). Calculation methods are provided to quantify active basal and insulin-stimulated rates, as well as stimulation fold.

Glucose Uptake Measurement and Response to Insulin Stimulation in In Vitro Cultured Human Primary Myotubes

In this method, human primary muscle cells are cultured in vitro to obtain differentiated myotubes and glucose uptake rates are measured. We provide a detailed protocol to quantify rates in basal and insulin-stimulated states using radiolabeled [3H] 2-deoxy-D-Glucose.

Medición de la Absorción de Glucosa y Respuesta a la Estimulación de la Insulina en<em&gt; In Vitro</em&gt; Myotubes primario humano cultivado

Skeletal muscle is the largest glucose deposit in mammals and largely contributes to glucose homeostasis. Assessment of insulin sensitivity of muscle ...

Confocal Imaging of Neuropeptide Y-pHluorin: A Technique to Visualize Insulin Granule Exocytosis in Intact Murine and Human Islets

Insulin secretion plays a central role in glucose homeostasis under normal physiological conditions as well as in disease. Current approaches to study insulin granule exocytosis either use electrophysiology or microscopy coupled to the expression of fluorescent reporters. However most of these techniques have been optimized for clonal cell lines or require dissociating pancreatic islets. In contrast, the method presented here allows for real time visualization of insulin granule exocytosis in intact pancreatic islets. In this protocol, we first describe the viral infection of isolated pancreatic islets with adenovirus that encodes a pH-sensitive green fluorescent protein (GFP), pHluorin, coupled to neuropeptide Y (NPY). Second, we describe the confocal imaging of islets five days after viral infection and how to monitor the insulin granule secretion. Briefly, the infected islets are placed on a coverslip on an imaging chamber and imaged under an upright laser-scanning confocal microscope while being continuously perfused with extracellular solution containing various stimuli. Confocal images spanning 50 &#181;m of the islet are acquired as time-lapse recordings using a fast-resonant scanner. The fusion of insulin granules with the plasma membrane can be followed over time. This procedure also allows for testing a battery of stimuli in a single experiment, is compatible with both mouse and human islets, and can be combined with various dyes for functional imaging (e.g., membrane potential or cytosolic calcium dyes).

We describe a protocol for visualization of insulin exocytosis in intact islets using pHluorin, a pH-sensitive green fluorescent protein. Isolated islets are infected with adenovirus encoding pHluorin coupled to the vesicle cargo neuropeptide Y. This allows for the detection of insulin granule fusion events by confocal microscopy.

De neuropéptido Y-pHluorin de la proyección de imagen confocal: una técnica para visualizar la exocitosis de gránulos de insulina en islotes humanos y murinos intactos

Insulin secretion plays a central role in glucose homeostasis under normal physiological conditions as well as in disease. Current approaches to study ...

Optical Cross-Sectional Muscle Area Determination of Drosophila Melanogaster Adult Indirect Flight Muscles

Muscle mass wasting, known as muscle atrophy, is a common phenotype in Drosophila models of neuromuscular diseases. We have used the indirect flight muscles (IFMs) of flies, specifically the dorso-longitudinal muscles (DLM), as the experimental subject to measure the atrophic phenotype brought about by different genetic causes. In this protocol, we describe how to embed fly thorax muscles for semi thin sectioning, how to obtain a good contrast between muscle and the surrounding tissue, and how to process optical microscope images for semiautomatic acquisition of quantifiable data and analysis. We describe three specific applications of the methodological pipeline. First, we show how the method can be applied to quantify muscle degeneration in a myotonic dystrophy fly model; second, measurement of muscle cross-sectional area can help to identify genes that either promote or prevent muscle atrophy and/or muscle degeneration; third, this protocol can be applied to determine whether a candidate compound is able to significantly modify a given atrophic phenotype induced by a disease-causing mutation or by an environmental trigger.

Optical Cross-Sectional Muscle Area Determination of Drosophila Melanogaster Adult Indirect Flight Muscles

We report a method to quantify muscle area, which is an indirect method to determine muscle mass in Drosophila adults. We demonstrate the application of our methodology by analyzing the indirect flight muscles in a Drosophila model of Myotonic Dystrophy disease.

Determinación de zona óptica transversal muscular de los músculos de vuelo indirectos adultos de Drosophila Melanogaster

Muscle mass wasting, known as muscle atrophy, is a common phenotype in Drosophila models of neuromuscular diseases. We have used the indirect flight ...

Oral Bacterial Infection and Shedding in Drosophila melanogaster

The fruit fly Drosophila melanogaster is one of the best developed model systems of infection and innate immunity. While most work has focused on systemic infections, there has been a recent increase of interest in the mechanisms of gut immunocompetence to pathogens, which require methods to orally infect flies. Here we present a protocol to orally expose individual flies to an opportunistic bacterial pathogen (Pseudomonas aeruginosa) and a natural bacterial pathogen of D. melanogaster (Pseudomonas entomophila). The goal of this protocol is to provide a robust method to expose male and female flies to these pathogens. We provide representative results showing survival phenotypes, microbe loads, and bacterial shedding, which is relevant for the study of heterogeneity in pathogen transmission. Finally, we confirm that Dcy mutants (lacking the protective peritrophic matrix in the gut epithelium) and Relish mutants (lacking a functional immune deficiency (IMD) pathway), show increased susceptibility to bacterial oral infection. This protocol, therefore, describes a robust method to infect flies using the oral route of infection, which can be extended to the study of a variety genetic and environmental sources of variation in gut infection outcomes and bacterial transmission.

Oral Bacterial Infection and Shedding in Drosophila melanogaster

This protocol describes methods to orally expose and infect the fruit fly Drosophila melanogaster with bacterial pathogens, and to measure the number of infectious bacteria shed following gut infection. We further describe the effect of immune mutants on fly survival following oral bacterial infection.

Oral infección bacteriana y vertimiento en Drosophila melanogaster

The fruit fly Drosophila melanogaster is one of the best developed model systems of infection and innate immunity. While most work has focused on systemic ...

Visualizing and Tracking Endogenous mRNAs in Live Drosophila melanogaster Egg Chambers

Fluorescence-based imaging techniques, in combination with developments in light microscopy, have revolutionized how cell biologists conduct live cell imaging studies. Methods for detecting RNAs have expanded greatly since seminal studies linked site-specific mRNA localization to gene expression regulation. Dynamic mRNA processes can now be visualized via approaches that detect mRNAs, coupled with microscopy set-ups that are fast enough to capture the dynamic range of molecular behavior. The molecular beacon technology is a hybridization-based approach capable of direct detection of endogenous transcripts in living cells. Molecular beacons are hairpin-shaped, internally quenched, single-nucleotide discriminating nucleic acid probes, which fluoresce only upon hybridization to a unique target sequence. When coupled with advanced fluorescence microscopy and high-resolution imaging, they enable one to perform spatial and temporal tracking of intracellular movement of mRNAs. Although this technology is the only method capable of detecting endogenous transcripts, cell biologists have not yet fully embraced this technology due to difficulties in designing such probes for live cell imaging. A new software application, PinMol, allows for enhanced and rapid design of probes best suited to efficiently hybridize to mRNA target regions within a living cell. In addition, high-resolution, real-time image acquisition and current, open source image analysis software allow for a refined data output, leading to a finer evaluation of the complexity underlying the dynamic processes involved in the mRNA&#39;s life cycle.
Here we present a comprehensive protocol for designing and delivering molecular beacons into Drosophila melanogaster egg chambers. Direct and highly specific detection and visualization of endogenous maternal mRNAs is performed via spinning disc confocal microscopy. Imaging data is processed and analyzed using object detection and tracking in Icy software to obtain details about the dynamic movement of mRNAs, which are transported and localized to specialized regions within the oocyte.

Visualizing and Tracking Endogenous mRNAs in Live Drosophila melanogaster Egg Chambers

Here, we present a protocol for the visualization, detection, analysis and tracking of endogenous mRNA trafficking in live Drosophila melanogaster egg chamber using molecular beacons, spinning disc confocal microscopy, and open-source analysis software.

Visualización y seguimiento de ARNm endógenos en cámaras de huevo Drosophila melanogaster en vivo

Fluorescence-based imaging techniques, in combination with developments in light microscopy, have revolutionized how cell biologists conduct live cell ...