Nous remercions Paavo Bergmann, Michael Laumann, et Sebastian Schmelzle pour leur aide à l&#39;ESRF. Ce travail a été soutenu par le projet European Synchrotron Radiation Facility SC-2127 par l&#39;attribution de temps de faisceau.

Les animaux utilisés dans cette étude Les spécimens de la parthénogénétiques oribates acariens Archegozetes longisetosus (Acari, Oribatides) ont été prises à partir de notre culture en laboratoire. La culture pousse sur un plâtre de Paris / mix charbon (9:1) dans des pots en plastique, dans l&#39;obscurité constante à 20-23 ° C avec environ 90% d&#39;humidité de l&#39;air. La préparation des échantillons <ol><li> Les échantillons ont été prélevés dans la culture, nettoyé avec un pinceau fin et placé dans un mélange 06:03:01 d&#39;éthanol 80%, formaldéhyde 35% et 100% d&#39;acide acétique pendant 24 heures. </li><li> Ensuite, les échantillons ont été déshydratés dans une série d&#39;éthanol à 70%, 75%, 80%, 85%, 90%, 95% et 100% avec 3 changements à chaque concentration, et à 10 min entre les étapes. </li><li> Enfin, les échantillons ont été placés au point éthanol frais de 100% durant la nuit et critique séchées en CO 2 (CPD 020, Balzers). Les spécimens séchés étaient attachés à l&#39;extrémité des broches en plastique (1,2 cm de long, 3,0 mm de diamètre). </li></ol> Synchrotron tomographie par rayons X Tomographie par rayons X a été réalisée à ligne de lumière ID19 (ESRF, Grenoble, France, expérimenter SC-2127). <ol><li> Les échantillons ont été montés dans le porte-échantillon et ajustée à une position centrale dans le faisceau. </li><li> Les échantillons ont été mesurées avec une énergie de 20,5 keV. Les radiographies ont été enregistrées avec un CCD refroidie (ESRF FRELON caméra) avec une gamme dynamique de 14 bits, 2048 × 2048 pixels et une taille de pixels effectifs de 0,7 um. 1500 projections ont été enregistrées au cours de la rotation de 180 ° de l&#39;échantillon avec un temps d&#39;exposition de 0,35 s pour chaque projection. La distance de détection à l&#39;échantillon était de 20 mm. </li></ol> Utiliser une certaine distance entre l&#39;échantillon et le détecteur permet une imagerie différentielle des matériaux à faible coefficient d&#39;atténuation des rayons X (Cloetens, et al. 1996), qui produirait un contraste insuffisant en matière d&#39;imagerie d&#39;absorption (où l&#39;échantillon est situé directement en face du détecteur ). La plupart des questions biologiques sont des objets de phase, composée de matériaux avec une faible absorption et / ou seulement de petites différences dans le numéro atomique (Betz et al. 2007). Cependant, la phase amélioré la tomographie de cohérence exige une haute résolution spatiale d&#39;une homogénéité faisceau de rayons X. Par conséquent, le rayonnement synchrotron est mieux adaptée que les scanners de bureau pour ce genre de mesures. L&#39;analyse des données <ol><li> Les radiographies résultant 2D ont été transformées en données 3D voxel (8-bit des valeurs de gris) avec une rétroprojection filtrée algorithme (Cloetens, et al., 1997) </li><li> Les données ont été analysées voxel avec le logiciel Max vgstudio 1.2.1. (Graphics tome, Heidelberg, Allemagne). </li><li> Gris-valeurs de l&#39;arrière-plan ont été retirés de l&#39;histogramme pour visualisation 3D. </li><li> Pré-définis caméra chemins ont été utilisés pour générer des animations de rotation et de plans de découpe animée. </li><li> Un chemin défini par l&#39;utilisateur caméra a été généré à suivre le système digestif de A. longisetosus. </li></ol>

<ol>
	<li>Betz, O., Wegst, U., Weide, D., Heethoff, M., Helfen, L., Lee, W. -. K., Cloetens, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Imaging+applications+of+synchrotron+X-ray+phase-contrast+microtomography+in+biological+morphology+and+biomaterial+science.+I.+General+aspects+of+the+technique+and+its+advantages+in+the+analysis+of+millimetre-sized+arthropod+structure.">Imaging applications of synchrotron X-ray phase-contrast microtomography in biological morphology and biomaterial science. I. General aspects of the technique and its advantages in the analysis of millimetre-sized arthropod structure.</a> J. Microscopy. 22, 51-71 (2007).</li><li>Cloetens, P., Barrett, R., Baruchel, J., Guigay, J. P., Schlenker, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Phase+objects+in+synchrotron+radiation+hard+X-ray+imaging.">Phase objects in synchrotron radiation hard X-ray imaging.</a> J. Phys. D: Appl. Phys. 29, 133-146 (1996).</li><li>Cloetens, P., Pateyron-Salome, M., Buffiere, J. Y., Peix, G., Baruchel, J., Peyrin, V., Schlenker, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Observation+in+microstructure+and+damage+in+materials+by+phase+sensitive+radiography+and+tomography.">Observation in microstructure and damage in materials by phase sensitive radiography and tomography.</a> J. Apll. Phys. 81, 5878-5886 (1997).</li><li>Clotens, P., Ludwig, W., Baruchel, J., van Dyck, D., van Landyut, J., Guigay, J. P., Schlenker, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Holotomography:+quantitative+phase+tomography+with+micrometer+resolution+using+hard+synchrotron+radiation+X-rays.">Holotomography: quantitative phase tomography with micrometer resolution using hard synchrotron radiation X-rays.</a> Appl. Phys. Lett. 75, 2912-2914 (1999).</li><li>Heethoff, M., Cloetens, 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+Comparison+of+aynchrotron+X-ray+phase+contrast+tomography+and+holotomography+for+non-invasive+investigations+of+the+internal+anatomy+of+mites.">A Comparison of aynchrotron X-ray phase contrast tomography and holotomography for non-invasive investigations of the internal anatomy of mites.</a> Soil Organisms. , (2008).</li></ol>

The authors have nothing to disclose.

Dans cette présentation, nous nous sommes concentrés sur la visualisation 3D de l&#39;anatomie interne d&#39;un micro-chelicerate arthropodes. Les rayons X synchrotron mesures permettent un pixel-résolution allant jusqu&#39;à 0.3μm, selon la taille de l&#39;échantillon. Ici, nous avons montré des données avec 0.7μm pixels de résolution. Généralement, synchrotron tomographie aux rayons X peut être utile pour analyser de petits matériels biologiques (ou des tissus) avec un faible atténuation des rayons X. Les pixels de résolut...

non-invasive 3d-visualization with sub-micron resolution using synchrotron-x-ray-tomography

On connaît mal l&#39;organisation interne de nombreux micro-arthropodes du corps avec des tailles inférieures à 1 mm. Les raisons en sont la petite taille et la cuticule dure ce qui rend difficile d&#39;utiliser des protocoles de l&#39;histologie classique. En outre, les coupes histologiques détruit l&#39;échantillon et ne peut donc pas être utilisé pour matériau unique. Ainsi, une méthode non destructive est souhaitable qui permet de visualiser l&#39;intérieur de petits échantillons sans avoir besoin de sectionnement. Nous avons utilisé synchrotron tomographie par rayons X à l&#39;European Synchrotron Radiation Facility (ESRF) à Grenoble (France) à la non-invasive de produire des ensembles de données 3D tomographique avec une résolution de pixel 0.7μm. En utilisant le logiciel de rendu de volume, ce qui nous permet de reconstituer l&#39;organisation interne dans son état naturel sans les artefacts produits par sectionnement histologique. Ces date peut être utilisé pour la morphologie quantitative, des repères, ou pour la visualisation de films d&#39;animation pour comprendre la structure des parties du corps cachés et de suivre les systèmes d&#39;organes ou de tissus complète à travers les échantillons.

Watch this Scientific Journal Video about Non-invasive 3D-Visualization with Sub-micron Resolution Using Synchrotron-X-ray-tomography at JoVE.com

Non-invasive 3D-Visualization with Sub-micron Resolution Using Synchrotron-X-ray-tomography

Nous avons utilisé synchrotron tomographie par rayons X à l&#39;European Synchrotron Radiation Facility (ESRF) pour produire de manière non invasive en 3D des jeux de données tomographiques avec un pixel résolution de 0.7μm. En utilisant le logiciel de rendu de volume, ce qui permet la reconstruction des structures internes dans leur état naturel sans les artefacts produits par sectionnement histologique.

Non-invasive visualisation 3D avec résolution submicronique utilisant synchrotron à rayons X-tomographie

Little is known about the internal organization of many micro-arthropods with body sizes below 1 mm. The reasons for that are the small size and the hard ...

non-invasive-3d-visualization-with-sub-micron-resolution-using

Research

JoVE Journal

Biology

13.0K vues.  University of Tubingen. Nous avons utilisé synchrotron tomographie par rayons X à l'European Synchrotron Radiation Facility (ESRF) pour produire de manière non invasive en 3D des jeux de données tomographiques avec un pixel résolution de 0.7μm. En utilisant le logiciel de rendu de volume, ce qui permet la reconstruction des structures internes dans leur état naturel sans les artefacts produits par sectionnement histologique.

Vidéo: Non-invasive 3D-Visualization with Sub-micron Resolution Using Synchrotron-X-ray-tomography

Labeling hESCs and hMSCs with Iron Oxide Nanoparticles for Non-Invasive in vivo Tracking with MR Imaging

In recent years, stem cell research has led to a better understanding of developmental biology, various diseases and its potential impact on regenerative medicine. A non-invasive method to monitor the transplanted stem cells repeatedly in vivo would greatly enhance our ability to understand the mechanisms that control stem cell death and identify trophic factors and signaling pathways that improve stem cell engraftment. MR imaging has been proven to be an effective tool for the in vivo depiction of stem cells with near microscopic anatomical resolution. In order to detect stem cells with MR, the cells have to be labeled with cell specific MR contrast agents. For this purpose, iron oxide nanoparticles, such as superparamagnetic iron oxide particles (SPIO), are applied, because of their high sensitivity for cell detection and their excellent biocompatibility. SPIO particles are composed of an iron oxide core and a dextran, carboxydextran or starch coat, and function by creating local field inhomogeneities, that cause a decreased signal on T2-weighted MR images. This presentation will demonstrate techniques for labeling of stem cells with clinically applicable MR contrast agents for subsequent non-invasive in vivo tracking of the labeled cells with MR imaging.

For the evaluation of new stem cell therapies it is important to non-invasively track the injected cells in vivo. This video will show you how to label human mesenchymal and embryonic stem cells with iron oxide based contrast agents in vivo for subsequent MR imaging in vivo.

Étiquetage CSEh et hMSCs d&#39;oxyde de fer nanoparticules pour les non-invasives dans le suivi in ​​vivo avec IRM

In recent years, stem cell research has led to a better understanding of developmental biology, various diseases and its potential impact on regenerative ...

Recherche

Biologie

Labeling Stem Cells with Fluorescent Dyes for non-invasive Detection with Optical Imaging

Optical imaging (OI) is an easy, fast and inexpensive tool for in vivo monitoring of new stem cell based therapies. The technique is based on ex vivo labeling of stem cells with a fluorescent dye, subsequent intravenous injection of the labeled cells and visualization of their accumulation in specific target organs or pathologies. The presented technique demonstrates how we label human mesenchymal stem cells (hMSC) by simple incubation with the lipophilic fluorescent dye DiD (C67H103CIN2O3S) and how we label human embryonic stem cells (hESC) with the FDA approved fluorescent dye Indocyanine Green (ICG). The uptake mechanism is via adherence and diffusion of the lypophilic dye across the phospholipid cell membrane bilayer. The labeling efficiency is usually improved if the cells are incubated with the dye in serum-free media as opposed to incubation in serum-containing media. Furthermore, the addition of the transfection agent Protamine Sulfate significantly improves contrast agent uptake.

This video shows techniques for labeling of human embryonic stem cells and mesenchymal stem cells with fluorescent dyes. This technique can be used for an in vivo tracking of transplanted stem cells with optical imaging and for histopathological correlations with fluorescence microscopy.

Étiquetage des cellules souches avec des colorants fluorescents pour les non-invasive de détection avec l&#39;imagerie optique

Optical imaging (OI) is an easy, fast and inexpensive tool for in vivo monitoring of new stem cell based therapies. The technique is based on ex vivo ...

A Reversible, Non-invasive Method for Airway Resistance Measurements and Bronchoalveolar Lavage Fluid Sampling in Mice

Airway hyperreactivity (AHR) measurements and bronchoalveolar lavage (BAL) fluid sampling are essential to experimental asthma models, but repeated procedures to obtain such measurements in the same animal are generally not feasible.  Here, we demonstrate protocols for obtaining from mice repeated measurements of AHR and bronchoalveolar lavage fluid samples.  Mice were challenged intranasally seven times over 14 days with a potent allergen or sham treated.  Prior to the initial challenge, and within 24 hours following each intranasal challenge, the same animals were anesthetized, orally intubated and mechanically ventilated.  AHR, assessed by comparing dose response curves of respiratory system resistance (RRS) induced by increasing intravenous doses of acetylcholine (Ach) chloride between sham and allergen-challenged animals, were determined.  Afterwards, and via the same intubation, the left lung was lavaged so that differential enumeration of airway cells could be performed.  These studies reveal that repeated measurements of AHR and BAL fluid collection are possible from the same animals and that maximal airway hyperresponsiveness and airway eosinophilia are achieved within 7-10 days of initiating allergen challenge.  This novel technique significantly reduces the number of mice required for longitudinal experimentation and is applicable to diverse rodent species, disease models and airway physiology instruments.  

Repeated measurements of rodent respiratory physiology and sampling of airway inflammatory cells are desirable, but generally not feasible. Here we describe a repeatable method for orally intubating mice that permits repeated measurements of airway hyperreactivity and sampling of airway inflammatory cells.

Une réversible, méthode non-invasive pour les mesures de résistance des voies aériennes et d&#39;échantillonnage du liquide de lavage broncho-alvéolaire chez des souris

Airway hyperreactivity (AHR) measurements and bronchoalveolar lavage (BAL) fluid sampling are essential to experimental asthma models, but repeated ...

iCLIP - Transcriptome-wide Mapping of Protein-RNA Interactions with Individual Nucleotide Resolution

The unique composition and spatial arrangement of RNA-binding proteins (RBPs) on a transcript guide the diverse aspects of post-transcriptional regulation1. Therefore, an essential step towards understanding transcript regulation at the molecular level is to gain positional information on the binding sites of RBPs2.
Protein-RNA interactions can be studied using biochemical methods, but these approaches do not address RNA binding in its native cellular context. Initial attempts to study protein-RNA complexes in their cellular environment employed affinity purification or immunoprecipitation combined with differential display or microarray analysis (RIP-CHIP)3-5. These approaches were prone to identifying indirect or non-physiological interactions6. In order to increase the specificity and positional resolution, a strategy referred to as CLIP (UV cross-linking and immunoprecipitation) was introduced7,8. CLIP combines UV cross-linking of proteins and RNA molecules with rigorous purification schemes including denaturing polyacrylamide gel electrophoresis. In combination with high-throughput sequencing technologies, CLIP has proven as a powerful tool to study protein-RNA interactions on a genome-wide scale (referred to as HITS-CLIP or CLIP-seq)9,10. Recently, PAR-CLIP was introduced that uses photoreactive ribonucleoside analogs for cross-linking11,12.
Despite the high specificity of the obtained data, CLIP experiments often generate cDNA libraries of limited sequence complexity. This is partly due to the restricted amount of co-purified RNA and the two inefficient RNA ligation reactions required for library preparation. In addition, primer extension assays indicated that many cDNAs truncate prematurely at the crosslinked nucleotide13. Such truncated cDNAs are lost during the standard CLIP library preparation protocol. We recently developed iCLIP (individual-nucleotide resolution CLIP), which captures the truncated cDNAs by replacing one of the inefficient intermolecular RNA ligation steps with a more efficient intramolecular cDNA circularization (Figure 1)14. Importantly, sequencing the truncated cDNAs provides insights into the position of the cross-link site at nucleotide resolution. We successfully applied iCLIP to study hnRNP C particle organization on a genome-wide scale and assess its role in splicing regulation14.

The spatial arrangement of RNA-binding proteins on a transcript is a key determinant of post-transcriptional regulation. Therefore, we developed individual-nucleotide resolution UV crosslinking and immunoprecipitation (iCLIP) that allows precise genome-wide mapping of the binding sites of an RNA-binding protein.

iClip - transcriptome à l&#39;échelle de cartographie des protéines-ARN Interactions avec résolution nucléotides individuels

The unique composition and spatial arrangement of RNA-binding proteins (RBPs) on a transcript guide the diverse aspects of post-transcriptional ...

Rapid and Efficient Zebrafish Genotyping Using PCR with High-resolution Melt Analysis

Zebrafish is a powerful vertebrate model system for studying development, modeling disease, and performing drug screening. Recently a variety of genetic tools have been introduced, including multiple strategies for inducing mutations and generating transgenic lines. However, large-scale screening is limited by traditional genotyping methods, which are time-consuming and labor-intensive. Here we describe a technique to analyze zebrafish genotypes by PCR combined with high-resolution melting analysis (HRMA).&#160;This approach is rapid, sensitive, and inexpensive, with lower risk of contamination artifacts.&#160;Genotyping by PCR with HRMA can be used for embryos or adult fish, including in high-throughput screening protocols.

PCR combined with high-resolution melt analysis (HRMA) is demonstrated as a rapid and efficient method to genotype zebrafish.

Le poisson zèbre rapide et efficace génotypage utilisant la PCR avec haute résolution Melt analyse

Zebrafish is a powerful vertebrate model system for studying development, modeling disease, and performing drug screening. Recently a variety of genetic ...

Who is Who? Non-invasive Methods to Individually Sex and Mark Altricial Chicks

Many experiments require early determination of offspring's sex as well as early marking of newborns for individual recognition. According to animal welfare guidelines, non-invasive techniques should be preferred whenever applicable. In our group, we work on different species of song birds in the lab and in the field, and we successfully apply non-invasive methods to sex and individually mark chicks. This paper presents a comprehensive non-invasive tool-box. Sexing birds prior to the expression of secondary sexual traits requires the collection of DNA-bearing material for PCR. We established a quick and easy method to sex birds of any age (post hatching) by extracting DNA from buccal swabs. Results can be obtained within 3 hours. For individual marking chick's down feathers are trimmed in specific patterns allowing fast identification within the hatching order. This set of methods is easily applicable in a standard equipped lab and especially suitable for working in the field as no special equipment is required for sampling and storage. Handling of chicks is minimized and marking and sexing techniques are non-invasive thereby supporting the RRR-principle of animal welfare guidelines.

This protocol provides a convenient set of methods, which enables extremely fast, easy, non-invasive, reliable and low-cost, molecular sex determination of birds and their non-invasive, quick, safe and easily recognizable marking shortly after hatching. Only limited handling of chicks is required. This convenient toolbox of methods complies entirely with the RRR-guidelines.

Qui est qui? Méthodes non-invasives pour Individuellement sexe et Mark nidicoles poussins

Many experiments require early determination of offspring's sex as well as early marking of newborns for individual recognition. According to animal ...

Fecal Glucocorticoid Analysis: Non-invasive Adrenal Monitoring in Equids

Adrenal activity can be assessed in the equine species by analysis of feces for corticosterone metabolites. During a potentially aversive situation, corticotrophin releasing hormone (CRH) is released from the hypothalamus in the brain. This stimulates the release of adrenocorticotrophic hormone (ACTH) from the pituitary gland, which in turn stimulates release of glucocorticoids from the adrenal gland. In horses the glucocorticoid corticosterone is responsible for several adaptations needed to support equine flight behaviour and subsequent removal from the aversive situation. Corticosterone metabolites can be detected in the feces of horses and assessment offers a non-invasive option to evaluate long term patterns of adrenal activity. Fecal assessment offers advantages over other techniques that monitor adrenal activity including blood plasma and saliva analysis. The non-invasive nature of the method avoids sampling stress which can confound results. It also allows the opportunity for repeated sampling over time and is ideal for studies in free ranging horses. This protocol describes the enzyme linked immunoassay (EIA) used to assess feces for corticosterone, in addition to the associated biochemical validation.

Adrenal activity can be assessed in the equine species by analysis of feces for corticosterone metabolites. The method offers a non-invasive option to assess long term patterns in both domestic and free ranging horses. This protocol describes the enzyme linked immunoassay involved and the associated biochemical validation.

Fecal glucocorticoïdes Analyse: Surveillance surrénale non invasive en Equidés

Adrenal activity can be assessed in the equine species by analysis of feces for corticosterone metabolites. During a potentially aversive situation, ...

Open-source Single-particle Analysis for Super-resolution Microscopy with VirusMapper

Super-resolution fluorescence microscopy is currently revolutionizing cell biology research. Its capacity to break the resolution limit of around 300 nm allows for the routine imaging of nanoscale biological complexes and processes. This increase in resolution also means that methods popular in electron microscopy, such as single-particle analysis, can readily be applied to super-resolution fluorescence microscopy. By combining this analytical approach with super-resolution optical imaging, it becomes possible to take advantage of the molecule-specific labeling capacity of fluorescence microscopy to generate structural maps of molecular elements within a metastable structure. To this end, we have developed a novel algorithm &#8212; VirusMapper &#8212; packaged as an easy-to-use, high-performance, and high-throughput ImageJ plugin. This article presents an in-depth guide to this software, showcasing its ability to uncover novel structural features in biological molecular complexes. Here, we present how to assemble compatible data and provide a step-by-step protocol on how to use this algorithm to apply single-particle analysis to super-resolution images.

This manuscript uses the Fiji-based open-source software package VirusMapper to apply single-particle analysis to super-resolution microscopy images in order to generate precise models of nanoscale structure.

Open Source Analyse unique pour particules super-résolution Microscopie avec VirusMapper

Super-resolution fluorescence microscopy is currently revolutionizing cell biology research. Its capacity to break the resolution limit of around 300 nm ...

Analysis of Beta-cell Function Using Single-cell Resolution Calcium Imaging in Zebrafish Islets

Pancreatic beta-cells respond to increasing blood glucose concentrations by secreting the hormone insulin. The dysfunction of beta-cells leads to hyperglycemia and severe, life-threatening consequences. Understanding how the beta-cells operate under physiological conditions and what genetic and environmental factors might cause their dysfunction could lead to better treatment options for diabetic patients. The ability to measure calcium levels in beta-cells serves as an important indicator of beta-cell function, as the influx of calcium ions triggers insulin release. Here we describe a protocol for monitoring the glucose-stimulated calcium influx in zebrafish beta-cells by using GCaMP6s, a genetically encoded sensor of calcium. The method allows monitoring the intracellular calcium dynamics with single-cell resolution in ex vivo mounted islets. The glucose-responsiveness of beta-cells within the same islet can be captured simultaneously under different glucose concentrations, which suggests the presence of functional heterogeneity among zebrafish beta-cells. Furthermore, the technique provides high temporal and spatial resolution, which reveals the oscillatory nature of the calcium influx upon glucose stimulation. Our approach opens the doors to use the zebrafish as a model to investigate the contribution of genetic and environmental factors to beta-cell function and dysfunction.

Beta-cell functionality is important for blood-glucose homeostasis, which is evaluated at single-cell resolution using a genetically encoded reporter for calcium influx.

Analyse de la fonction des cellules bêta à l’aide d’imagerie calcique résolution unicellulaire dans les îlots de poisson-zèbre

Pancreatic beta-cells respond to increasing blood glucose concentrations by secreting the hormone insulin. The dysfunction of beta-cells leads to ...

Isolating Myofibrils from Skeletal Muscle Biopsies and Determining Contractile Function with a Nano-Newton Resolution Force Transducer

Striated muscle cells are indispensable for the activity of humans and animals. Single muscle fibers are comprised of myofibrils, which consist of serially linked sarcomeres, the smallest contractile units in muscle. Sarcomeric dysfunction contributes to muscle weakness in patients with mutations in genes encoding for sarcomeric proteins. The study of myofibril mechanics allows for the assessment of actin-myosin interactions without potential confounding effects of damaged, adjacent myofibrils when measuring the contractility of single muscle fibers. Ultrastructural damage and misalignment of myofibrils might contribute to impaired contractility. If structural damage is present in the myofibrils, they likely break during the isolation procedure or during the experiment. Furthermore, studies in myofibrils provide the assessment of actin-myosin interactions in the presence of the geometrical constraints of the sarcomeres. For instance, measurements in myofibrils can elucidate whether myofibrillar dysfunction is the primary effect of a mutation in a sarcomeric protein. In addition, perfusion with calcium solutions or compounds is almost instant due to the small diameter of the myofibril. This makes myofibrils eminently suitable to measure the rates of activation and relaxation during force production. The protocol described in this paper employs an optical force probe based on the principle of a Fabry-P&#233;rot interferometer capable of measuring forces in the nano-Newton range, coupled to a piezo length motor and a fast-step perfusion system. This setup enables the study of myofibril mechanics with high resolution force measurements.

Presented here is a protocol to assess the contractile properties of striated muscle myofibrils with nano-Newton resolution. The protocol employs a setup with an interferometry-based, optical force probe. This setup generates data with a high signal-to-noise ratio and enables the assessment of the contractile kinetics of myofibrils.

Isoler les myofibrils des biopsies des muscles squelettiques et déterminer la fonction contractile avec un transducteur de force de résolution nano-newton