Wir bedanken uns bei Paavo Bergmann, Michael Laumann und Sebastian Schmelzle für ihre Hilfe bei der ESRF. Diese Arbeit wurde von der European Synchrotron Radiation Facility-Projekt SC-2127 durch die Zuteilung von Strahlzeit unterstützt.

Tiere in dieser Studie verwendeten Die Proben der parthenogenetischen Hornmilben mite Archegozetes longisetosus (Acari, Oribatida) wurden aus unserem Labor Kultur genommen. Die Kultur wächst auf einem Gips / Kohle mischen (9:1) in Plastikdosen, in ständiger Dunkelheit bei 20-23 ° C mit ca. 90% Luftfeuchtigkeit. Probenvorbereitung <ol><li> Die Proben wurden aus der Kultur entnommen, gereinigt mit einem feinen Pinsel und in einen 06.03.01 Mischung aus 80% Ethanol, 35% Formaldehyd und 100% Essigsäure für 24 Stunden. </li><li> Danach wurden die Proben in einer abgestuften Reihe von Ethanol 70%, 75%, 80%, 85%, 90%, 95% und 100% mit 3 Änderungen bei jeder Konzentration, und 10 min zwischen den Schritten dehydriert. </li><li> Schließlich wurden die Proben in frischem 100% Ethanol über Nacht und kritischer Punkt in CO 2 getrocknet (CPD 020, Balzers) platziert. Getrocknete Proben wurden bis zur Spitze des Kunststoff-Stifte (, 3,0 mm im Durchmesser 1,2 cm lang) befestigt. </li></ol> Synchrotron-Röntgen-Tomographie X-ray-Tomographie wurde am Strahlrohr ID19 (ESRF, Grenoble, Frankreich, Experiment SC-2127) durchgeführt. <ol><li> Die Proben wurden in der Probe-Halterung montiert und justiert, um eine zentrale Stellung in den Strahl. </li><li> Die Proben wurden mit einer Energie von 20,5 keV gemessen. Die Röntgenbilder wurden mit einer gekühlten CCD (ESRF Frelon Kamera) mit einem 14-Bit Dynamikbereich, 2048 × 2048 Pixeln und eine effektive Pixelgröße von 0,7 um aufgezeichnet. 1500 Projektionen wurden über die 180 ° Rotation Probe mit einer Belichtungszeit von 0,35 s für jede Projektion aufgezeichnet. Der Detektor-Probe-Abstand betrug 20 mm. </li></ol> Mit einem gewissen Abstand zwischen Probe und Detektor ermöglicht eine differentielle Darstellung von Materialien mit geringer X-ray Schwächungskoeffizienten (Cloetens, et al. 1996), die aufgrund des geringen Kontrasts in Absorption Imaging produzieren (wobei die Probe direkt vor dem Detektor befinden würde ). Die meisten biologischen Fragen sind Phase-Objekte, von Materialien mit geringer Absorption und / oder nur geringe Unterschiede in der Ordnungszahl (Betz et al. 2007) zusammen. Allerdings erfordert Phase verbesserte Tomographie eine hohe räumliche Kohärenz einer homogenen Röntgenstrahl. Daher ist Synchrotronstrahlung besser als Desktop-Scanner für diese Art von Messungen geeignet. Datenanalyse <ol><li> Die daraus resultierende 2D-Röntgenbilder wurden um 3D Voxeldaten (8-Bit-Graustufen-Werte) mit einer gefilterten Rückprojektion Algorithmus (Cloetens, et al., 1997) transformiert </li><li> Die Voxel-Daten wurden mit der Software VGStudio Max 1.2.1 analysiert. (Volume Graphics, Heidelberg, Deutschland). </li><li> Grey-Werte aus dem Hintergrund wurden aus dem Histogramm für 3D-Visualisierung entfernt. </li><li> Vordefinierte Kamera-Pfade wurden verwendet, um Dreh-Animationen und animierte Schnittebenen zu erzeugen. </li><li> Eine benutzerdefinierte Kamera-Pfad erzeugt wurde, um das Verdauungssystem des A. folgen 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.

In dieser Präsentation, konzentrierten wir uns auf die 3D-Visualisierung der inneren Anatomie eines chelicerate Mikro-Arthropoden. Die Synchrotron-Röntgen-Messungen erlauben eine Pixel-Auflösung von bis zu 0.3μm, abhängig von der Größe der Stichprobe. Hier haben wir Daten mit 0.7μm Pixel-Auflösung dargestellt. Generell kann Synchrotron-Tomographie sinnvoll sein, für die Analyse von kleinen biologischen Materialien (oder Gewebe) mit niedrigem Röntgendämpfung. Die Pixel-Auflösung erreicht fast die von herkömmlichen Lichtmikrosko...

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

Wenig ist über die interne Organisation der vielen Mikro-Arthropoden mit Körpergrößen unter 1 mm bekannt. Die Gründe dafür sind die geringe Größe und die harte Nagelhaut ist es schwierig, Protokolle der klassischen Histologie Einsatz macht. Darüber hinaus zerstört histologische Schnitte der Probe und kann daher nicht für einzigartige Material verwendet werden. Daher ist eine zerstörungsfreie Methode wünschenswert, die in kleinen Proben ohne die Notwendigkeit der Einteilung anzeigen können. Wir verwendeten Synchrotron-Tomographie an der European Synchrotron Radiation Facility (ESRF) in Grenoble (Frankreich) um nicht-invasiv zu produzieren 3D-tomographischen Datensätze mit einer Pixel-Auflösung von 0.7μm. Mit Volume-Rendering-Software, ermöglicht uns auf die interne Organisation in ihrem natürlichen Zustand ohne Artefakte durch histologische Schnitte hergestellt rekonstruieren. Diese Datum kann für quantitative Morphologie, Sehenswürdigkeiten oder für die Visualisierung von animierten Filmen eingesetzt werden, um die Struktur der verborgenen Körperteile zu verstehen und komplette Organsysteme oder Gewebe durch die Proben folgen.

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

Wir verwendeten Synchrotron-Tomographie an der European Synchrotron Radiation Facility (ESRF) in nicht-invasiv zu produzieren 3D-tomographischen Datensätze mit einer Pixel-Auflösung von 0.7μm. Mit Volume-Rendering-Software, ermöglicht dies die Rekonstruktion der internen Strukturen in ihrem natürlichen Zustand ohne Artefakte durch histologische Schnitte hergestellt.

Nicht-invasive 3D-Visualisierung mit Sub-Mikron-Auflösung mit Synchrotron-Röntgen-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 Aufrufe.  University of Tubingen. Wir verwendeten Synchrotron-Tomographie an der European Synchrotron Radiation Facility (ESRF) in nicht-invasiv zu produzieren 3D-tomographischen Datensätze mit einer Pixel-Auflösung von 0.7μm. Mit Volume-Rendering-Software, ermöglicht dies die Rekonstruktion der internen Strukturen in ihrem natürlichen Zustand ohne Artefakte durch histologische Schnitte hergestellt.

Serie: 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.

Labeling hESCs und hMSCs mit Eisenoxid-Nanopartikel für Non-Invasive in vivo-Tracking mit MR-Bildgebung

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

Forschung

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.

Labeling Stammzellen mit fluoreszierenden Farbstoffen zur nicht-invasiven Detektion mit 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 ...

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.

Eine reversible, nicht-invasive Methode für Airway Resistance-Messungen und bronchoalveolären Lavage Sampling in Mäuse

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 - Transkriptom-weiten Mapping von Protein-RNA Wechselwirkungen mit Individual Nucleotide Resolution

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.

Schnelle und effiziente Verwendung von Zebrafisch-Genotypisierung PCR mit Hochauflösende Schmelzanalyse

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.

Wer ist wer? Nicht-invasive Methoden zur Individuell Sex und Mark Nesthocker Chicks

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 Glucocorticoid-Analyse: Nicht-invasive Monitoring-Adrenal in Equids

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-Einzelpartikelanalyse für Super Resolution Mikroskopie mit 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 der Beta-Zellfunktion mit einzelligen Auflösung Kalzium Imaging im Zebrafisch Inselchen

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.