우리는 ESRF에서 자신의 도움을 파보 누르 버그만, 마이클 라우먼, 그리고 세바스찬 Schmelzle 감사드립니다. 이 작품은 빔 시간의 배분을 통해 유럽 싱크로 트론 방사선 시설 사업 SC - 2127에 의해 지원되었다.

이 연구에 사용된 동물 parthenogenetic oribatid 마이트 Archegozetes longisetosus (Acari, Oribatida)의 표본은 우리의 연구실 문화에서 찍은. 문화가 20-23에서 지속적인 어둠 속에서, 파리 / 플라스틱 항아리에 숯 믹스 (9시 1분)의 석고의 성장 ° C 공기 습도 약 90 %를. 샘플 준비 <ol><li> 표본은 좋은 브러시로 청소하고 24 시간 동안 80 % 에탄올, 35 % 포름 알데히드 100 % 초산의 6시 3분 1초 혼합 배치, 문화에서 찍은. </li><li> 그 후, 표본은 각 농도 3 변경하고, 단계 사이에 10 분있는 등급 에탄올 70 % 시리즈, 75 %, 80 %, 85 %, 90 %, 95%, 100 %에 탈수있었습니다. </li><li> 마지막으로 샘플은 CO 2의 건조 신선한 100 % 에탄올 하룻밤과 임계점 (CPD 020, Balzers)에 배치했다. 말린 표본는 플라스틱 핀이의 끝 (; 직경 3.0 mm 길이 1.2 ㎝)에 첨부했습니다. </li></ol> 싱크로 트론 X - 선 tomography X - 선 tomography는 beamline ID19 (ESRF, 그르노블, 프랑스,​​ 실험 SC - 2127)에서 수행되었다. <ol><li> 샘플은 샘플 홀더에 장착하고 빔의 중앙 위치로 조정되었습니다. </li><li> 샘플은 20.5 케빈의 에너지를 측정했다. radiographs은 14 비트 다이나믹 레인지로 냉각 CCD (ESRF 프렐론 카메라), 2,048 × 2,048 픽셀과 0.7 μm의의 효과적인 픽셀 크기로 기록되었다. 1500 계획은 각 투영 0.35 s의 노출 시간과 180 ° 샘플 회전을 통해 기록했다. 검출기 - 투 - 샘플 거리가 20mm되었습니다. </li></ol> 샘플과 검출기 사이에 일정한 거리를 사용하면 (샘플은 검출기의 바로 앞에 위치 흡수 이미징에 충분한 대비를 생성 낮은 X - 선 감쇠 계수 (Cloetens, 외. 1996)과 재료의 차등 이미징을 가능하게 ). 대부분의 생물 학적 문제는 낮은 흡수 및 / 또는 원자 번호에만 작은 차이 (베츠, 외. 2007)과 재료의 구성 단계 개체입니다. 그러나, 위상 강화 tomography은 단일 X - 선 빔 높은 공간적 일관성이 필요합니다. 따라서, 싱크로 트론 방사는 더 나은 측정 이러한 종류의 데스크탑 스캐너보다 적합합니다. 데이터 분석 <ol><li> 그 결과 2D radiographs은 필터링된 다시 프로젝션 알고리즘 (Cloetens, 외., 1997)와 3D voxel 데이터 (8 비트 회색 값)으로 변형되었다 </li><li> voxel 데이터는 소프트웨어 VGStudio 최대 1.2.1로 분석했다. (볼륨 그래픽, 하이 델베르크, 독일). </li><li> 배경에서 그레이 - 값이 3D - 시각화에 대한 히스토그램에서 제거되었습니다. </li><li> 사전 정의된 카메라 경로는 회전 애니메이션과 애니메이션 클리핑 비행기를 생성하는 데 사용되었습니다. </li><li> 사용자 정의 카메라 경로 A.의 소화 시스템에 따라 생성되었습니다 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.

이 프레 젠 테이션에서, 우리는 chelicerate 마이크로 arthropod의 내부 해부의 3D - 시각화에 초점을 맞추었습니다. 싱크로 트론 X - 선 측정은 샘플의 크기에 따라, 0.3μm로의 픽셀 해상도를 허용합니다. 여기, 우리는 픽셀 해상도 0.7μm 데이터를 표시합니다. 일반적으로, 싱크로 트론 X - 선 tomography 낮은 X - 선 감쇠와 함께 작은 생물 학적 물질 (또는 조직)를 분석하는 데 유용할 수 있습니다. 픽셀 해상도는 거의 전통적인...

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

리틀은 1mm 아래의 신체 크기와 많은 마이크로 arthropods의 내부 조직에 대한 알려져있다. 에 대한 이유는 작은 크기와 어려운 클래식 조직학의 프로토콜을 사용할 수 있습니다 하드 표피입니다. 또한, histological sectioning는 샘플을 파괴하기 때문에 독특한 소재에 대해 사용할 수 없습니다. 따라서 비파괴 방법 sectioning의 필요없이 작은 샘플 안에서 볼 수 있습니다하는 것이 바람직하다. 우리는 비 invasively 0.7μm의 픽셀 해상도와 3D 단층 데이터 세트를 생성 그르노블 (프랑스)의 유럽 싱크로 트론 방사선 시설 (ESRF)에 싱크로 트론 X - 선 tomography를 사용했습니다. 볼륨 렌더링 소프트웨어를 사용, 이것은 우리 histological sectioning 제작한 공예품없이 자연 상태에서 내부 조직을 재구성 할 수 있습니다. 이 날짜는 숨겨진 신체 부위의 구조를 이해하고 예제를 통해 전체 기관의 시스템이나 조직에 따라 정량 형태, 랜드마크, 또는 애니메이션 영​​화의 시각화를 위해 사용할 수 있습니다.

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

우리는 비 invasively 0.7μm의 픽셀 해상도와 3D 단층 데이터 세트를 생산하는 유럽 싱크로 트론 방사선 시설 (ESRF)에 싱크로 트론 X - 선 tomography를 사용했습니다. 볼륨 렌더링 소프트웨어를 사용하여이 histological sectioning 제작한 공예품없이 자연 상태에서 내부 구조의 재건 수 있습니다.

싱크로 트론 - X - 레이 - tomography를 사용하여 서브 마이크론 해상도로 비침습 3D - 시각화

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 조회수.  University of Tubingen. 우리는 비 invasively 0.7μm의 픽셀 해상도와 3D 단층 데이터 세트를 생산하는 유럽 싱크로 트론 방사선 시설 (ESRF)에 싱크로 트론 X - 선 tomography를 사용했습니다. 볼륨 렌더링 소프트웨어를 사용하여이 histological sectioning 제작한 공예품없이 자연 상태에서 내부 구조의 재건 수 있습니다.

비디오: 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.

이런 산화물로 hESCs과 hMSCs을 라벨링하는 MR 영상과 생체내 추적 비침습에 대한 Nanoparticles

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

연구

생물학

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.

광학 이미징과 비침습 감지를위한 형광 염료와 함께 줄기 세포를 라벨링

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.

에어웨이 저항 측정 및 마우스에 Bronchoalveolar 세척 유체 샘플링에 대한 가역, 비침습 방법

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 - 개인 염기 해상도와 단백질 RNA 상호 작용의 Transcriptome 전체 매핑

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.

고해상도 용융 분석과 PCR을 이용하여 신속하고 효율적인 Zebrafish의 유전자형

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.

누구는 누구입니까? 비 침습적 인 방법 개별적으로 섹스와 마크 Altricial 병아리

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.

대변​​ 글루코 코르티코이드 분석 : equids는 비 침습적 부신 모니터링

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.

VirusMapper 슈퍼 해상도 현미경을위한 오픈 소스 단일 입자 분석

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.

Zebrafish 독도에서 단일 셀 해상도 칼슘 이미징 사용 하 여 베타 세포 기능 분석

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.