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Sonnen KF, Merten CA. Microfluidics as an Emerging Precision Tool in Developmental Biology. Dev Cell 2019; 48:293-311. [PMID: 30753835 DOI: 10.1016/j.devcel.2019.01.015] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Revised: 12/13/2018] [Accepted: 01/10/2019] [Indexed: 12/18/2022]
Abstract
Microfluidics has become a precision tool in modern biology. It enables omics data to be obtained from individual cells, as compared to averaged signals from cell populations, and it allows manipulation of biological specimens in entirely new ways. Cells and organisms can be perturbed at extraordinary spatiotemporal resolution, revealing mechanistic insights that would otherwise remain hidden. In this perspective article, we discuss the current and future impact of microfluidic technology in the field of developmental biology. In addition, we provide detailed information on how to start using this technology even without prior experience.
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Affiliation(s)
| | - Christoph A Merten
- Genome Biology Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany.
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2
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Zimmerman JF, Murray GF, Wang Y, Jumper JM, Austin JR, Tian B. Free-Standing Kinked Silicon Nanowires for Probing Inter- and Intracellular Force Dynamics. NANO LETTERS 2015; 15:5492-8. [PMID: 26192816 DOI: 10.1021/acs.nanolett.5b01963] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Silicon nanowires (SiNWs) have emerged as a new class of materials with important applications in biology and medicine with current efforts having focused primarily on using substrate bound SiNW devices. However, developing devices capable of free-standing inter- and intracellular operation is an important next step in designing new synthetic cellular materials and tools for biophysical characterization. To demonstrate this, here we show that label free SiNWs can be internalized in multiple cell lines, forming robust cytoskeletal interfaces, and when kinked can serve as free-standing inter- and intracellular force probes capable of continuous extended (>1 h) force monitoring. Our results show that intercellular interactions exhibit ratcheting like behavior with force peaks of ∼69.6 pN/SiNW, while intracellular force peaks of ∼116.9 pN/SiNW were recorded during smooth muscle contraction. To accomplish this, we have introduced a simple single-capture dark-field/phase contrast optical imaging modality, scatter enhanced phase contrast (SEPC), which enables the simultaneous visualization of both cellular components and inorganic nanostructures. This approach demonstrates that rationally designed devices capable of substrate-independent operation are achievable, providing a simple and scalable method for continuous inter- and intracellular force dynamics studies.
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Affiliation(s)
- John F Zimmerman
- †Department of Chemistry, ‡The Institute for Biophysical Dynamics, and §The James Franck Institute, University of Chicago, Chicago, Illinois 60637, United States
| | - Graeme F Murray
- †Department of Chemistry, ‡The Institute for Biophysical Dynamics, and §The James Franck Institute, University of Chicago, Chicago, Illinois 60637, United States
| | - Yucai Wang
- †Department of Chemistry, ‡The Institute for Biophysical Dynamics, and §The James Franck Institute, University of Chicago, Chicago, Illinois 60637, United States
| | - John M Jumper
- †Department of Chemistry, ‡The Institute for Biophysical Dynamics, and §The James Franck Institute, University of Chicago, Chicago, Illinois 60637, United States
| | - Jotham R Austin
- †Department of Chemistry, ‡The Institute for Biophysical Dynamics, and §The James Franck Institute, University of Chicago, Chicago, Illinois 60637, United States
| | - Bozhi Tian
- †Department of Chemistry, ‡The Institute for Biophysical Dynamics, and §The James Franck Institute, University of Chicago, Chicago, Illinois 60637, United States
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3
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DiMarco RL, Su J, Yan KS, Dewi R, Kuo CJ, Heilshorn SC. Engineering of three-dimensional microenvironments to promote contractile behavior in primary intestinal organoids. Integr Biol (Camb) 2014; 6:127-142. [PMID: 24343706 DOI: 10.1039/c3ib40188j] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Multiple culture techniques now exist for the long-term maintenance of neonatal primary murine intestinal organoids in vitro; however, the achievement of contractile behavior within cultured organoids has thus far been infrequent and unpredictable. Here we combine finite element simulation of oxygen transport and quantitative comparative analysis of cellular microenvironments to elucidate the critical variables that promote reproducible intestinal organoid contraction. Experimentally, oxygen distribution was manipulated by adjusting the ambient oxygen concentration along with the use of semi-permeable membranes to enhance transport. The culture microenvironment was further tailored through variation of collagen type-I matrix density, addition of exogenous R-spondin1, and specification of culture geometry. "Air-liquid interface" cultures resulted in significantly higher numbers of contractile cultures relative to traditional submerged cultures. These interface cultures were confirmed to have enhanced and more symmetric oxygen transport relative to traditional submerged cultures. While oxygen availability was found to impact in vitro contraction rate and the orientation of contractile movement, it was not a key factor in enabling contractility. For all conditions tested, reproducible contractile behavior only occurred within a consistent and narrow range of collagen type-I matrix densities with porosities of approximately 20% and storage moduli near 30 Pa. This suggests that matrix density acts as a "permissive switch" that enables contractions to occur. Similarly, contractions were only observed in cultures with diameters less than 15.5 mm that had relatively large interfacial surface area between the compliant matrix and the rigid culture dish. Taken together, these data suggest that spatial geometry and mechanics of the microenvironment, which includes both the encapsulating matrix as well as the surrounding culture device, may be key determinants of intestinal organoid functionality. As peristaltic contractility is a crucial requirement for normal digestive tract function, this achievement of reproducible organoid contraction marks a pivotal advancement towards engineering physiologically functional replacement tissue constructs.
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Affiliation(s)
- Rebecca L DiMarco
- Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - James Su
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA
| | - Kelley S Yan
- Department of Medicine, Hematology Division, Stanford University School of Medicine, Stanford, CA, USA
| | - Ruby Dewi
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA
| | - Calvin J Kuo
- Department of Medicine, Hematology Division, Stanford University School of Medicine, Stanford, CA, USA
| | - Sarah C Heilshorn
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA
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4
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Kodera N, Ando T. The path to visualization of walking myosin V by high-speed atomic force microscopy. Biophys Rev 2014; 6:237-260. [PMID: 25505494 PMCID: PMC4256461 DOI: 10.1007/s12551-014-0141-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2013] [Accepted: 05/07/2014] [Indexed: 01/14/2023] Open
Abstract
The quest for understanding the mechanism of myosin-based motility started with studies on muscle contraction. From numerous studies, the basic frameworks for this mechanism were constructed and brilliant hypotheses were put forward. However, the argument about the most crucial issue of how the actin-myosin interaction generates contractile force and shortening has not been definitive. To increase the "directness of measurement", in vitro motility assays and single-molecule optical techniques were created and used. Consequently, detailed knowledge of the motility of muscle myosin evolved, which resulted in provoking more arguments to a higher level. In parallel with technical progress, advances in cell biology led to the discovery of many classes of myosins. Myosin V was discovered to be a processive motor, unlike myosin II. The processivity reduced experimental difficulties because it allowed continuous tracing of the motor action of single myosin V molecules. Extensive studies of myosin V were expected to resolve arguments and build a consensus but did not necessarily do so. The directness of measurement was further enhanced by the recent advent of high-speed atomic force microscopy capable of directly visualizing biological molecules in action at high spatiotemporal resolution. This microscopy clearly visualized myosin V molecules walking on actin filaments and at last provided irrefutable evidence for the swinging lever-arm motion propelling the molecules. However, a peculiar foot stomp behavior also appeared in the AFM movie, raising new questions of the chemo-mechanical coupling in this motor and myosin motors in general. This article reviews these changes in the research of myosin motility and proposes new ideas to resolve the newly raised questions.
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Affiliation(s)
- Noriyuki Kodera
- Bio-AFM Frontier Research Center, Kanazawa University, Kanazawa, 920-1192 Japan
- PREST, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, 332-0012 Japan
| | - Toshio Ando
- Bio-AFM Frontier Research Center, Kanazawa University, Kanazawa, 920-1192 Japan
- Department of Physics, College of Science and Engineering, Kanazawa University, Kakuma-machi, Kanazawa, 920-1192 Japan
- CREST, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, 332-0012 Japan
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5
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Farcasanu IC, Mitrica R, Cristache L, Nicolau I, Ruta LL, Paslaru L, Comorosan S. Optical manipulation ofSaccharomyces cerevisiaecells reveals that green light protection against UV irradiation is favored by low Ca2+and requires intact UPR pathway. FEBS Lett 2013; 587:3514-21. [DOI: 10.1016/j.febslet.2013.09.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Revised: 09/05/2013] [Accepted: 09/10/2013] [Indexed: 12/16/2022]
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6
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Shen MY, Michaelson J, Huang H. Rheological responses of cardiac fibroblasts to mechanical stretch. Biochem Biophys Res Commun 2012; 430:1028-33. [PMID: 23261449 DOI: 10.1016/j.bbrc.2012.12.044] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2012] [Accepted: 12/10/2012] [Indexed: 10/27/2022]
Abstract
Rheological characterization of cells using passive particle tracking techniques can yield substantial information regarding local cellular material properties. However, limited work has been done to establish the changes in material properties of mechanically-responsive cells that experience external stimuli. In this study, cardiac fibroblasts plated on either fibronectin or collagen were treated with cytochalasin, mechanically stretched, or both, and their trajectories and complex moduli were extracted. Results demonstrate that both solid and fluid components were altered by such treatments in a receptor-dependent manner, and that, interestingly, cells treated with cytochalasin were still capable of stiffening in response to mechanical stimuli despite gross stress fiber disruption. These results suggest that the material properties of cells are dependent on a variety of environmental cues and can provide insight into physiological and disease processes.
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Affiliation(s)
- Min Ye Shen
- Columbia University, New York, NY 10027, USA
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8
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Robert D, Fayol D, Le Visage C, Frasca G, Brulé S, Ménager C, Gazeau F, Letourneur D, Wilhelm C. Magnetic micro-manipulations to probe the local physical properties of porous scaffolds and to confine stem cells. Biomaterials 2009; 31:1586-95. [PMID: 19932922 DOI: 10.1016/j.biomaterials.2009.11.014] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2009] [Accepted: 11/03/2009] [Indexed: 10/20/2022]
Abstract
The in vitro generation of engineered tissue constructs involves the seeding of cells into porous scaffolds. Ongoing challenges are to design scaffolds to meet biochemical and mechanical requirements and to optimize cell seeding in the constructs. In this context, we have developed a simple method based on a magnetic tweezer set-up to manipulate, probe, and position magnetic objects inside a porous scaffold. The magnetic force acting on magnetic objects of various sizes serves as a control parameter to retrieve the local viscosity of the scaffolds internal channels as well as the stiffness of the scaffolds pores. Labeling of human stem cells with iron oxide magnetic nanoparticles makes it possible to perform the same type of measurement with cells as probes and evaluate their own microenvironment. For 18 microm diameter magnetic beads or magnetically labeled stem cells of similar diameter, the viscosity was equivalently equal to 20 mPa s in average. This apparent viscosity was then found to increase with the magnetic probes sizes. The stiffness probed with 100 microm magnetic beads was found in the 50 Pa range, and was lowered by a factor 5 when probed with cells aggregates. The magnetic forces were also successfully applied to the stem cells to enhance the cell seeding process and impose a well defined spatial organization into the scaffold.
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Affiliation(s)
- Damien Robert
- Laboratoire Matière et Systèmes Complexes (MSC), UMR 7057 CNRS & Université Paris Diderot, Paris, France
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Kim DH, Wong PK, Park J, Levchenko A, Sun Y. Microengineered platforms for cell mechanobiology. Annu Rev Biomed Eng 2009; 11:203-33. [PMID: 19400708 DOI: 10.1146/annurev-bioeng-061008-124915] [Citation(s) in RCA: 236] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Mechanical forces play important roles in the regulation of various biological processes at the molecular and cellular level, such as gene expression, adhesion, migration, and cell fate, which are essential to the maintenance of tissue homeostasis. In this review, we discuss emerging bioengineered tools enabled by microscale technologies for studying the roles of mechanical forces in cell biology. In addition to traditional mechanobiology experimental techniques, we review recent advances of microelectromechanical systems (MEMS)-based approaches for cell mechanobiology and discuss how microengineered platforms can be used to generate in vivo-like micromechanical environment in in vitro settings for investigating cellular processes in normal and pathophysiological contexts. These capabilities also have significant implications for mechanical control of cell and tissue development and cell-based regenerative therapies.
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Affiliation(s)
- Deok-Ho Kim
- Department of Biomedical Engineering, The Johns Hopkins University, Baltimore, Maryland 21218, USA.
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10
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Abstract
The "conventional" isoform of myosin that polymerizes into filaments (myosin II) is the molecular motor powering contraction in all three types of muscle. Considerable attention has been paid to the developmental progression, isoform distribution, and mutations that affect myocardial development, function, and adaptation. Optical trap (laser tweezer) experiments and various types of high-resolution fluorescence microscopy, capable of interrogating individual protein motors, are revealing novel and detailed information about their functionally relevant nanometer motions and pico-Newton forces. Single-molecule laser tweezer studies of cardiac myosin isoforms and their mutants have helped to elucidate the pathogenesis of familial hypertrophic cardiomyopathies. Surprisingly, some disease mutations seem to enhance myosin function. More broadly, the myosin superfamily includes more than 20 nonfilamentous members with myriad cellular functions, including targeted organelle transport, endocytosis, chemotaxis, cytokinesis, modulation of sensory systems, and signal transduction. Widely varying genetic, developmental and functional disorders of the nervous, pigmentation, and immune systems have been described in accordance with these many roles. Compared to the collective nature of myosin II, some myosin family members operate with only a few partners or even alone. Individual myosin V and VI molecules can carry cellular vesicular cargoes much farther distances than their own size. Laser tweezer mechanics, single-molecule fluorescence polarization, and imaging with nanometer precision have elucidated the very different mechano-chemical properties of these isoforms. Critical contributions of nonsarcomeric myosins to myocardial development and adaptation are likely to be discovered in future studies, so these techniques and concepts may become important in cardiovascular research.
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Affiliation(s)
- Jody A Dantzig
- University of Pennsylvania School of Medicine, Pennsylvania Muscle Institute, 3700 Hamilton Walk, D700 Richards Building, Philadelphia, PA 19104-6083, USA
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11
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Abstract
We outline the basic principles of optical tweezers as well as the fundamental theory underlying optical tweezers. The optical forces responsible for trapping result from the transfer of momentum from the trapping beam to the particle and are explained in terms of the momenta of incoming and reflected or refracted rays. We also consider the angular momentum flux of the beam in order to understand and explain optical torques. In order to provide a qualitative picture of the trapping, we treat the particle as a weak positive lens and the forces on the lens are shown. However, this representation does not provide quantitative results for the force. We, therefore, present results of applying exact electromagnetic theory to optical trapping. First, we consider a tightly focused laser beam. We give results for trapping of spherical particles and examine the limits of trappability in terms of type and size of the particles. We also study the effect of a particle on the beam. This exact solution reproduces the same qualitative effect as when treating the particle as a lens where changes in the convergence or divergence and in the direction of the trapping beam result in restoring forces acting on the particle. Finally, we review the fundamental theory of optical tweezers.
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Affiliation(s)
- Timo A Nieminen
- Centre for Biophotonics and Laser Science, School of Physical Sciences, The University of Queensland, Brisbane QLD 4072, Australia
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12
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Uhde J, Ter-Oganessian N, Pink DA, Sackmann E, Boulbitch A. Viscoelasticity of entangled actin networks studied by long-pulse magnetic bead microrheometry. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2005; 72:061916. [PMID: 16485983 DOI: 10.1103/physreve.72.061916] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2005] [Indexed: 05/06/2023]
Abstract
We studied the viscoelastic response of entangled actin networks using embedded microbeads driven by force pulses with amplitudes in the range from 3 to 120 pN and durations up to 60 s. We distinguished three regimes in the time dependence of the compliance J(t) of the network. These were characterized by specific power laws J(t) approximately t(alpha)(i) (i=1, 2, 3). In the short-time regime (i=1), we observed the exponent alpha1 approximately 0.75. In the long-time regime (i=3), we find that alpha3 approximately 1. For the intermediate-time interval (i=2), we observed a novel dynamic regime: for all actin concentrations and all applied forces, it was characterized by the exponent alpha3 approximately 0.5. In both regimes i=2 and i=3, the compliance depended upon the actin concentration c, such as J approximately c(-gamma)(i) with gamma2 approximately 1.1 and gamma 3 approximately 1.4. Using these results, we calculated the shear modulus in the frequency domain and found that the intermediate-time regime in the t domain corresponds to its plateau behavior.
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Affiliation(s)
- Jorg Uhde
- Department for Biophysics, Technical University of Munich, James-Franck-Strasse 1, D-85747 Garching at Munich, Germany
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13
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. VIV. Modulation of Dissociation Kinetics by External Force: Examination of the Bell Model. ACTA ACUST UNITED AC 2005. [DOI: 10.3923/jbs.2005.744.758] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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14
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Wang YL. The mechanism of cortical ingression during early cytokinesis: thinking beyond the contractile ring hypothesis. Trends Cell Biol 2005; 15:581-8. [PMID: 16209923 DOI: 10.1016/j.tcb.2005.09.006] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2005] [Revised: 08/22/2005] [Accepted: 09/20/2005] [Indexed: 11/24/2022]
Abstract
Owing to the rapid advances in genomic, proteomic and imaging technologies, the field of cytokinesis has seen rapid advances during the past decade. However, the basic model for the early stage of ingression, known as the contractile ring hypothesis, remains largely unchanged. From recent observations, it is becoming clear that early cytokinesis of animal cells involves a more extensive set of events, both temporally and spatially, than what is encompassed by the original contractile ring hypothesis. Activities relevant to cytokinesis, such as cortical contraction, can initiate well before onset of anaphase. Furthermore, equatorial ingression can involve multiple events in different regions of the cortex, including the establishment of anterior-posterior polarity, the modulation of cortical deformability, the expansion and compression of the cell cortex, and forces directed towards the interior of the cell or away from the equator. In this article (which is part of the Cytokinesis series), I evaluate critically key observations on when, where and how early ingression of animal cells takes place.
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Affiliation(s)
- Yu-li Wang
- University of Massachusetts Medical School, 377 Plantation Street, Suite 327, Worcester, MA 01605, USA.
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15
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Ter-Oganessian N, Quinn B, Pink DA, Boulbitch A. Active microrheology of networks composed of semiflexible polymers: computer simulation of magnetic tweezers. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2005; 72:041510. [PMID: 16383388 DOI: 10.1103/physreve.72.041510] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2005] [Indexed: 05/05/2023]
Abstract
We have simulated the motion of a bead subjected to a constant force while embedded in a network of semiflexible polymers which can represent actin filaments. We find that the bead displacement obeys the power law x approximately t(alpha). After the initial stage characterized by the exponent alpha1 approximately 0.75, we find a different regime with alpha2 approximately 0.5. The response in this regime is linear in force and scales with the polymer concentration as c(-1.4). We find that the polymers pile up ahead of the moving bead, while behind it the polymer density is reduced. We show that the force resisting the bead motion is due to steric repulsion exerted by the polymers on the front hemisphere of the bead.
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Affiliation(s)
- Nikita Ter-Oganessian
- Department for Biophysics E22, Technical University Munich, James-Franck-Strasse 1, D-85747 Garching, Germany
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16
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Abstract
The ultimate goal of all signaling pathways in cytokinesis is to control the mechanical separation of the mother cell into two daughter cells. Because of the intrinsic mechanical nature of cytokinesis, it is essential to understand fully how cell shapes and the material properties of the cell are generated, how these shapes and material properties create force, and how motor proteins such as myosin-II modify the system to achieve successful cytokinesis. In this review (which is part of the Cytokinesis series), we discuss the relevant physical properties of cells, how these properties are measured and the basic models that are used to understand cell mechanics. Finally, we present our current understanding of how cytokinesis mechanics work.
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Affiliation(s)
- Elizabeth M Reichl
- Department of Cell Biology, Johns Hopkins University School of Medicine, 725 N. Wolfe St., Baltimore, MD 21205, USA
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17
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Jass J, Schedin S, Fällman E, Ohlsson J, Nilsson UJ, Uhlin BE, Axner O. Physical properties of Escherichia coli P pili measured by optical tweezers. Biophys J 2004; 87:4271-83. [PMID: 15377509 PMCID: PMC1304935 DOI: 10.1529/biophysj.104.044867] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2004] [Accepted: 09/14/2004] [Indexed: 11/18/2022] Open
Abstract
The mechanical behavior of individual P pili of uropathogenic Escherichia coli has been investigated using optical tweezers. P pili, whose main part constitutes the PapA rod, composed of approximately 10(3) PapA subunits in a helical arrangement, are distributed over the bacterial surface and mediate adhesion to host cells. They are particularly important in the pathogenesis of E. coli colonizing the upper urinary tract and kidneys. A biological model system has been established for in situ measurements of the forces that occur during mechanical stretching of pili. A mathematical model of the force-versus-elongation behavior of an individual pilus has been developed. Three elongation regions of pili were identified. In region I, P pili stretch elastically, up to a relative elongation of 16 +/- 3%. The product of elasticity modulus and area of a P pilus, EA, was assessed to 154 +/- 20 pN (n=6). In region II, the quaternary structure of the PapA rod unfolds under a constant force of 27 +/- 2 pN (n approximately 100) by a sequential breaking of the interactions between adjacent layers of PapA subunits. This unfolding can elongate the pilus up to 7 +/- 2 times. In region III, pili elongate in a nonlinear manner as a result of stretching until the bond ruptures.
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Affiliation(s)
- Jana Jass
- Department of Microbiology and Immunology, The Lawson Health Research Institute, University of Western Ontario, London, Ontario, N6A 4V2, Canada
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18
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Brehm-Stecher BF, Johnson EA. Single-cell microbiology: tools, technologies, and applications. Microbiol Mol Biol Rev 2004; 68:538-59, table of contents. [PMID: 15353569 PMCID: PMC515252 DOI: 10.1128/mmbr.68.3.538-559.2004] [Citation(s) in RCA: 297] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The field of microbiology has traditionally been concerned with and focused on studies at the population level. Information on how cells respond to their environment, interact with each other, or undergo complex processes such as cellular differentiation or gene expression has been obtained mostly by inference from population-level data. Individual microorganisms, even those in supposedly "clonal" populations, may differ widely from each other in terms of their genetic composition, physiology, biochemistry, or behavior. This genetic and phenotypic heterogeneity has important practical consequences for a number of human interests, including antibiotic or biocide resistance, the productivity and stability of industrial fermentations, the efficacy of food preservatives, and the potential of pathogens to cause disease. New appreciation of the importance of cellular heterogeneity, coupled with recent advances in technology, has driven the development of new tools and techniques for the study of individual microbial cells. Because observations made at the single-cell level are not subject to the "averaging" effects characteristic of bulk-phase, population-level methods, they offer the unique capacity to observe discrete microbiological phenomena unavailable using traditional approaches. As a result, scientists have been able to characterize microorganisms, their activities, and their interactions at unprecedented levels of detail.
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Affiliation(s)
- Byron F Brehm-Stecher
- Department of Food Microbiology and Toxicology, University of Wisconsin-Madison Food Research Institute, 1925 Willow Drive, Madison, WI 53706, USA
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Abstract
Since their invention just over 20 years ago, optical traps have emerged as a powerful tool with broad-reaching applications in biology and physics. Capabilities have evolved from simple manipulation to the application of calibrated forces on-and the measurement of nanometer-level displacements of-optically trapped objects. We review progress in the development of optical trapping apparatus, including instrument design considerations, position detection schemes and calibration techniques, with an emphasis on recent advances. We conclude with a brief summary of innovative optical trapping configurations and applications.
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Affiliation(s)
- Keir C. Neuman
- Department of Biological Sciences, and Department of Applied Physics, Stanford University, Stanford, California 94305
| | - Steven M. Block
- Department of Biological Sciences, and Department of Applied Physics, Stanford University, Stanford, California 94305
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20
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Hu S, Eberhard L, Chen J, Love JC, Butler JP, Fredberg JJ, Whitesides GM, Wang N. Mechanical anisotropy of adherent cells probed by a three-dimensional magnetic twisting device. Am J Physiol Cell Physiol 2004; 287:C1184-91. [PMID: 15213058 DOI: 10.1152/ajpcell.00224.2004] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We describe a three-dimensional magnetic twisting device that is useful in characterizing the mechanical properties of cells. With the use of three pairs of orthogonally aligned coils, oscillatory mechanical torque was applied to magnetic beads about any chosen axis. Frequencies up to 1 kHz could be attained. Cell deformation was measured in response to torque applied via an RGD-coated, surface-bound magnetic bead. In both unpatterned and micropatterned elongated cells on extracellular matrix, the mechanical stiffness transverse to the long axis of the cell was less than half that parallel to the long axis. Elongated cells on poly-L-lysine lost stress fibers and exhibited little mechanical anisotropy; disrupting the actin cytoskeleton or decreasing cytoskeletal tension substantially decreased the anisotropy. These results suggest that mechanical anisotropy originates from intrinsic cytoskeletal tension within the stress fibers. Deformation patterns of the cytoskeleton and the nucleolus were sensitive to loading direction, suggesting anisotropic mechanical signaling. This technology may be useful for elucidating the structural basis of mechanotransduction.
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Affiliation(s)
- Shaohua Hu
- Physiology Program, Harvard School of Public Health, Boston, MA 02115, USA.
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21
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Affiliation(s)
- Daniel L Farkas
- Department of Surgery, Cedars-Sinai Medical Center, 8700 Beverly Blvd., Los Angeles California 90048, USA.
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22
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Zieziulewicz TJ, Unfricht DW, Hadjout N, Lynes MA, Lawrence DA. Shrinking the biologic world--nanobiotechnologies for toxicology. Toxicol Sci 2003; 74:235-44. [PMID: 12832654 DOI: 10.1093/toxsci/kfg108] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Although toxicologic effects need to be considered at the organismal level, the adverse events originate from interactions and alterations at the molecular level. Cellular structures and functions can be disrupted by modifications of the nanometer structure of critical molecules; therefore, devices used to assess biologic and toxicologic processes at the nanoscale will allow important new research pursuits. In order to properly assess alterations at these dimensions, nanofabricated tools are needed to detect, separate, analyze, and manipulate cells or biologic molecules of interest. The emergence of laser tweezers, surface plasmon resonance (SPR), laser capture microdissection (LCM), atomic force microscopy (AFM), and multi-photon microscopes have allowed for these assessments. Micro- and nanobiotechnologies will further advance biologic, clinical, and toxicologic endeavors with the aid of miniaturized, more sensitive devices. Miniaturized table-top laboratory equipment incorporating additional innovative technologies can lead to new advances, including micro total analysis systems (microTAS) or "lab-on-a-chip" and "sentinel sensor" devices. This review will highlight several devices, which have been made possible by techniques originating in the microelectronics industry. These devices can be used for toxicologic assessment of cellular structures and functions, such as cellular adhesion, signal transduction, motility, deformability, metabolism, and secretion.
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Affiliation(s)
- Thomas J Zieziulewicz
- Laboratory of Clinical and Experimental Endocrinology and Immunology, Wadsworth Center, New York State Department of Health, Albany, New York 12201, USA
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Coirault C, Pourny JC, Lambert F, Lecarpentier Y. [Optical tweezers in biology and medicine]. Med Sci (Paris) 2003; 19:364-7. [PMID: 12836420 DOI: 10.1051/medsci/2003193364] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Optical trapping techniques provide unique means to manipulate biological particles such as virus, living cells and subcellular organelles. Another area of interest is the measurement of mechanical (elastic) properties of cell membranes, long strands of single DNA molecule, and filamentous proteins. One of the most attractive applications is the study of single motor molecules. With optical tweezers traps, one can measure the forces generated by single motor molecules such as kinesin and myosin, in the piconewton range and, for the first time, resolve their detailed stepping motion.
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Affiliation(s)
- Catherine Coirault
- Inserm-Laboratoire d'Optique Appliquée-Ensta-Ecole Polytechnique, Centre de l'Yvette, 91761 Palaiseau, France.
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