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Abstract
BACKGROUND Endothelial cells (ECs) sense the forces from blood flow through the glycocalyx, a carbohydrate rich luminal surface layer decorating most cells, and through forces transmitted through focal adhesions (FAs) on the abluminal side of the cell. OBJECTIVES This perspective paper explores a complementary hypothesis, that glycocalyx molecules on the abluminal side of the EC between the basement membrane and the EC membrane, occupying the space outside of FAs, work in concert with FAs to sense blood flow-induced shear stress applied to the luminal surface. RESULTS First, we summarize recent studies suggesting that the glycocalyx repels the plasma membrane away from the basement membrane, while integrin molecules attach to extracellular matrix (ECM) ligands. This coordinated attraction and repulsion results in the focal nature of integrin-mediated adhesion making the abluminal glycocalyx a participant in mechanotransduction. Further, the glycocalyx mechanically links the plasma membrane to the basement membrane providing a mechanism of force transduction when the cell deforms in the peri-FA space. To determine if the membrane might deform against a restoring force of an elastic abluminal glycocalyx in the peri-FA space we present some analysis from a multicomponent elastic finite element model of a sheared and focally adhered endothelial cell whose abluminal topography was assessed using quantitative total internal reflection fluorescence microscopy with an assumption that glycocalyx fills the space between the membrane and extracellular matrix. CONCLUSIONS While requiring experimental verification, this analysis supports the hypothesis that shear on the luminal surface can be transmitted to the abluminal surface and deform the cell in the vicinity of the focal adhesions, with the magnitude of deformation depending on the abluminal glycocalyx modulus.
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Affiliation(s)
- Peter J Butler
- Department of Biomedical Engineering and Intercollege Graduate Program of Bioengineering, The Pennsylvania State University, University Park, PA, USA
| | - Amit Bhatnagar
- Department of Biomedical Engineering and Intercollege Graduate Program of Bioengineering, The Pennsylvania State University, University Park, PA, USA
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2
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Abstract
This Perspective paper advances a hypothesis of mechanosensation by endothelial cells in which the cell is a dynamic crowded system, driven by continuous enzyme activity, that can be shifted from one non-equilibrium state to another by external force. The nature of the shift will depend on the direction, rate of change, and magnitude of the force. Whether force induces a pathophysiological or physiological change in cell biology will be determined by whether the dynamics of a cellular system can accommodate the dynamics and magnitude of the force application. The complex interplay of non-static cytoskeletal structures governs internal cellular rheology, dynamic spatial reorganization, and chemical kinetics of proteins such as integrins, and a flaccid membrane that is dynamically supported; each may constitute the necessary dynamic properties able to sense external fluid shear stress and reorganize in two and three dimensions. The resulting reorganization of enzyme systems in the cell membrane and cytoplasm may drive the cell to a new physiological state. This review focuses on endothelial cell mechanotransduction of shear stress, but may lead to new avenues of investigation of mechanobiology in general requiring new tools for interrogation of mechanobiological systems, tools that will enable the synthesis of large amounts of spatial and temporal data at the molecular, cellular, and system levels.
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Affiliation(s)
- Peter J. Butler
- Department of Biomedical Engineering The Pennsylvania State University University Park, Pennsylvania 16802, USA
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3
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Abstract
The occurrence of different sponge species bearing the same Linnean binomial name combination, i.e. homonyms, is to be avoided for obvious reasons. In a review of sponge taxon names of the World Porifera Database, we detected 121 homonymic cases (115 species-group names, 6 genus-group names), involving a total of 272 nominal taxa. It is the object of the present study to remove their occurrence by proposing new names for the junior homonyms following the rules of the International Commission of Zoological Nomenclature as laid down in the Code (ICZN, 1999) and the on-line edition http://iczn.org/iczn/index.jsp . Homonym cases are discussed and, where applicable, junior homonyms are either replaced by nomina nova or reassigned to their earliest available synonyms. The order in which the homonyms are treated is alphabetical on original species name, with genus names separately treated at the end. A summary table with all proposed name changes is also presented to allow quick access to the junior homonyms and their proposed new names. A total of 116 nomina nova are proposed, including five new genus names.
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Affiliation(s)
- Rob W M VAN Soest
- Naturalis Biodiversity Center, P.O. Box 9517, 2300 RA Leiden, The Netherlands.
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4
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Abstract
Autonomous nanovehicles powered by energy derived from chemical catalysis have potential applications as active delivery agents. For in vivo applications, it is necessary that the engine and its fuel, as well as the chassis itself, be biocompatible. Enzyme molecules have been shown to display enhanced motility through substrate turnover and are attractive candidates as engines; phospholipid vesicles are biocompatible and can serve as cargo containers. Herein, we describe the autonomous movement of vesicles with membrane-bound enzymes in the presence of the substrate. We find that the motility of the vesicles increases with increasing enzymatic turnover rate. The enhanced diffusion of these enzyme-powered systems was further substantiated in real time by tracking the motion of the vesicles using optical microscopy. The membrane-bound protocells that move by transducing chemical energy into mechanical motion serve as models for motile living cells and are key to the elucidation of the fundamental mechanisms governing active membrane dynamics and cellular movement.
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5
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Feroz H, Ferlez B, Lefoulon C, Ren T, Baker CS, Gajewski JP, Lugar DJ, Gaudana SB, Butler PJ, Hühn J, Lamping M, Parak WJ, Hibberd JM, Kerfeld CA, Smirnoff N, Blatt MR, Golbeck JH, Kumar M. Light-Driven Chloride Transport Kinetics of Halorhodopsin. Biophys J 2019; 115:353-360. [PMID: 30021110 DOI: 10.1016/j.bpj.2018.06.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Revised: 05/19/2018] [Accepted: 06/05/2018] [Indexed: 01/25/2023] Open
Abstract
Despite growing interest in light-driven ion pumps for use in optogenetics, current estimates of their transport rates span two orders of magnitude due to challenges in measuring slow transport processes and determining protein concentration and/or orientation in membranes in vitro. In this study, we report, to our knowledge, the first direct quantitative measurement of light-driven Cl- transport rates of the anion pump halorohodopsin from Natronomonas pharaonis (NpHR). We used light-interfaced voltage clamp measurements on NpHR-expressing oocytes to obtain a transport rate of 219 (± 98) Cl-/protein/s for a photon flux of 630 photons/protein/s. The measurement is consistent with the literature-reported quantum efficiency of ∼30% for NpHR, i.e., 0.3 isomerizations per photon absorbed. To reconcile our measurements with an earlier-reported 20 ms rate-limiting step, or 35 turnovers/protein/s, we conducted, to our knowledge, novel consecutive single-turnover flash experiments that demonstrate that under continuous illumination, NpHR bypasses this step in the photocycle.
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Affiliation(s)
- Hasin Feroz
- Department of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania
| | - Bryan Ferlez
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania
| | - Cecile Lefoulon
- Laboratory of Plant Physiology and Biophysics, Institute of Molecular Cell and Systems Biology, University of Glasgow, Glasgow, United Kingdom
| | - Tingwei Ren
- Department of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania
| | - Carol S Baker
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania
| | - John P Gajewski
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania
| | - Daniel J Lugar
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania
| | - Sandeep B Gaudana
- MSU-DOE Plant Research Laboratory and Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan
| | - Peter J Butler
- Department of Biomedical Engineering, The Pennsylvania State University, University Park, Pennsylvania
| | - Jonas Hühn
- Department of Physics and Chemistry, Philipps University of Marburg, Marburg, Germany
| | - Matthias Lamping
- Department of Physics and Chemistry, Philipps University of Marburg, Marburg, Germany
| | - Wolfgang J Parak
- Department of Physics and Chemistry, Philipps University of Marburg, Marburg, Germany
| | - Julian M Hibberd
- Department of Plant Sciences, University of Cambridge, Cambridge, United Kingdom
| | - Cheryl A Kerfeld
- MSU-DOE Plant Research Laboratory and Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan; Department of Plant and Microbial Biology, University of California Berkeley, Berkeley, California; Environmental Genomics and Systems Biology, Lawrence Berkeley National Laboratory, Berkeley, California
| | | | - Michael R Blatt
- Laboratory of Plant Physiology and Biophysics, Institute of Molecular Cell and Systems Biology, University of Glasgow, Glasgow, United Kingdom
| | - John H Golbeck
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania; Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania
| | - Manish Kumar
- Department of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania.
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6
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Abstract
The cellular cytoplasm is crowded with macromolecules and other species that occupy up to 40% of the available volume. Previous studies have reported that for high crowder molecule concentrations, colloidal tracer particles have a dampened diffusion due to the higher solution viscosity. However, these studies employed uniform distributions of crowder molecules. We report a scenario, previously unexplored experimentally, of increased tracer transport driven by a nonuniform concentration of crowder macromolecules. In gradients of a polymeric crowder, tracer particles undergo transport several times higher than that of their bulk diffusion rate. The direction of the transport is toward regions of lower crowder concentration. Mechanistically, hard-sphere interactions and the resulting volume exclusion between the tracer and crowder increase the effective diffusion by inducing a convective motion of tracers, which we explain through modeling. Strikingly, soft deformable particles show even greater enhancement in transport in crowder gradients compared to similarly sized hard particles. Overall, this demonstration of enhanced transport in nonuniform distributions of crowders is anticipated to clarify aspects of multicomponent intracellular transport.
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7
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Linton SS, Abraham T, Liao J, Clawson GA, Butler PJ, Fox T, Kester M, Matters GL. Tumor-promoting effects of pancreatic cancer cell exosomes on THP-1-derived macrophages. PLoS One 2018; 13:e0206759. [PMID: 30383833 PMCID: PMC6211741 DOI: 10.1371/journal.pone.0206759] [Citation(s) in RCA: 77] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Accepted: 10/18/2018] [Indexed: 12/18/2022] Open
Abstract
Pancreatic ductal adenocarcinoma (PDAC) tumor growth is enhanced by tumor-associated macrophages (TAMs), yet the mechanisms by which tumor cells and TAMs communicate are not fully understood. Here we show that exosomes secreted by PDAC cell lines differed in their surface proteins, lipid composition, and efficiency of fusing with THP-1-derived macrophages in vitro. Exosomes from AsPC-1, an ascites-derived human PDAC cell line, were enriched in ICAM-1, which mediated their docking to macrophages through interactions with surface-exposed CD11c on macrophages. AsPC-1 exosomes also contained much higher levels of arachidonic acid (AA), and they fused at a higher rate with THP-1-derived macrophages than did exosomes from other PDAC cell lines or from an immortalized normal pancreatic ductal epithelial cell line (HPDE) H6c7. Phospholipase A2 enzymatic cleavage of arachidonic acid from AsPC-1 exosomes reduced fusion efficiency. PGE2 secretion was elevated in macrophages treated with AsPC-1 exosomes but not in macrophages treated with exosomes from other cell lines, suggesting a functional role for the AsPC-1 exosome-delivered arachidonic acid in macrophages. Non-polarized (M0) macrophages treated with AsPC-1 exosomes had increased levels of surface markers indicative of polarization to an immunosuppressive M2-like phenotype (CD14hi CD163hi CD206hi). Furthermore, macrophages treated with AsPC-1 exosomes had significantly increased secretion of pro-tumoral, bioactive molecules including VEGF, MCP-1, IL-6, IL-1β, MMP-9, and TNFα. Together, these results demonstrate that compared to exosomes from other primary tumor-derived PDAC cell lines, AsPC-1 exosomes alter THP-1-derived macrophage phenotype and function. AsPC-1 exosomes mediate communication between tumor cells and TAMs that contributes to tumor progression.
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Affiliation(s)
- Samuel S. Linton
- Department of Biochemistry and Molecular Biology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania, United States of America
| | - Thomas Abraham
- Department of Neural and Behavioral Sciences, Pennsylvania State University College of Medicine, Hershey, Pennsylvania, United States of America
| | - Jason Liao
- Department of Public Health Sciences, Pennsylvania State University College of Medicine, Hershey, Pennsylvania, United States of America
| | - Gary A. Clawson
- Department of Pathology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania, United States of America
| | - Peter J. Butler
- Department of Engineering, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Todd Fox
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia, United States of America
| | - Mark Kester
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia, United States of America
| | - Gail L. Matters
- Department of Biochemistry and Molecular Biology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania, United States of America
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8
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Shen YX, Song W, Barden DR, Ren T, Lang C, Feroz H, Henderson CB, Saboe PO, Tsai D, Yan H, Butler PJ, Bazan GC, Phillip WA, Hickey RJ, Cremer PS, Vashisth H, Kumar M. Publisher Correction: Achieving high permeability and enhanced selectivity for Angstrom-scale separations using artificial water channel membranes. Nat Commun 2018; 9:3304. [PMID: 30108220 PMCID: PMC6092424 DOI: 10.1038/s41467-018-05447-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Affiliation(s)
- Yue-Xiao Shen
- Department of Chemical Engineering, The Pennsylvania State University, University Park, PA, 16802, USA.,Department of Chemistry, University of California, Berkeley, CA, 94720, USA
| | - Woochul Song
- Department of Chemical Engineering, The Pennsylvania State University, University Park, PA, 16802, USA
| | - D Ryan Barden
- Department of Chemical Engineering, University of New Hampshire, Durham, NH, 03824, USA
| | - Tingwei Ren
- Department of Chemical Engineering, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Chao Lang
- Department of Chemical Engineering, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Hasin Feroz
- Department of Chemical Engineering, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Codey B Henderson
- Department of Chemistry, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Patrick O Saboe
- Department of Chemical Engineering, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Daniel Tsai
- Department of Chemical Engineering, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Hengjing Yan
- Center for Polymers and Organic Solids, University of California at Santa Barbara, Santa Barbara, CA, 93106, USA
| | - Peter J Butler
- Department of Biomedical Engineering, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Guillermo C Bazan
- Center for Polymers and Organic Solids, University of California at Santa Barbara, Santa Barbara, CA, 93106, USA
| | - William A Phillip
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, IN, 46556, USA
| | - Robert J Hickey
- Department of Material Science and Engineering, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Paul S Cremer
- Department of Chemistry, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Harish Vashisth
- Department of Chemical Engineering, University of New Hampshire, Durham, NH, 03824, USA
| | - Manish Kumar
- Department of Chemical Engineering, The Pennsylvania State University, University Park, PA, 16802, USA. .,Department of Biomedical Engineering, The Pennsylvania State University, University Park, PA, 16802, USA. .,Department of Civil and Environmental Engineering, The Pennsylvania State University, University Park, PA, 16802, USA.
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9
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Shen YX, Song W, Barden DR, Ren T, Lang C, Feroz H, Henderson CB, Saboe PO, Tsai D, Yan H, Butler PJ, Bazan GC, Phillip WA, Hickey RJ, Cremer PS, Vashisth H, Kumar M. Achieving high permeability and enhanced selectivity for Angstrom-scale separations using artificial water channel membranes. Nat Commun 2018; 9:2294. [PMID: 29895901 PMCID: PMC5997692 DOI: 10.1038/s41467-018-04604-y] [Citation(s) in RCA: 63] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Accepted: 05/09/2018] [Indexed: 01/05/2023] Open
Abstract
Synthetic polymer membranes, critical to diverse energy-efficient separations, are subject to permeability-selectivity trade-offs that decrease their overall efficacy. These trade-offs are due to structural variations (e.g., broad pore size distributions) in both nonporous membranes used for Angstrom-scale separations and porous membranes used for nano to micron-scale separations. Biological membranes utilize well-defined Angstrom-scale pores to provide exceptional transport properties and can be used as inspiration to overcome this trade-off. Here, we present a comprehensive demonstration of such a bioinspired approach based on pillar[5]arene artificial water channels, resulting in artificial water channel-based block copolymer membranes. These membranes have a sharp selectivity profile with a molecular weight cutoff of ~ 500 Da, a size range challenging to achieve with current membranes, while achieving a large improvement in permeability (~65 L m-2 h-1 bar-1 compared with 4-7 L m-2 h-1 bar-1) over similarly rated commercial membranes.
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Affiliation(s)
- Yue-Xiao Shen
- Department of Chemical Engineering, The Pennsylvania State University, University Park, PA, 16802, USA
- Department of Chemistry, University of California, Berkeley, CA, 94720, USA
| | - Woochul Song
- Department of Chemical Engineering, The Pennsylvania State University, University Park, PA, 16802, USA
| | - D Ryan Barden
- Department of Chemical Engineering, University of New Hampshire, Durham, NH, 03824, USA
| | - Tingwei Ren
- Department of Chemical Engineering, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Chao Lang
- Department of Chemical Engineering, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Hasin Feroz
- Department of Chemical Engineering, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Codey B Henderson
- Department of Chemistry, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Patrick O Saboe
- Department of Chemical Engineering, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Daniel Tsai
- Department of Chemical Engineering, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Hengjing Yan
- Center for Polymers and Organic Solids, University of California at Santa Barbara, Santa Barbara, CA, 93106, USA
| | - Peter J Butler
- Department of Biomedical Engineering, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Guillermo C Bazan
- Center for Polymers and Organic Solids, University of California at Santa Barbara, Santa Barbara, CA, 93106, USA
| | - William A Phillip
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, IN, 46556, USA
| | - Robert J Hickey
- Department of Material Science and Engineering, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Paul S Cremer
- Department of Chemistry, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Harish Vashisth
- Department of Chemical Engineering, University of New Hampshire, Durham, NH, 03824, USA
| | - Manish Kumar
- Department of Chemical Engineering, The Pennsylvania State University, University Park, PA, 16802, USA.
- Department of Biomedical Engineering, The Pennsylvania State University, University Park, PA, 16802, USA.
- Department of Civil and Environmental Engineering, The Pennsylvania State University, University Park, PA, 16802, USA.
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10
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Dabagh M, Jalali P, Butler PJ, Randles A, Tarbell JM. Mechanotransmission in endothelial cells subjected to oscillatory and multi-directional shear flow. J R Soc Interface 2018; 14:rsif.2017.0185. [PMID: 28515328 DOI: 10.1098/rsif.2017.0185] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Accepted: 04/21/2017] [Indexed: 12/27/2022] Open
Abstract
Local haemodynamics are linked to the non-uniform distribution of atherosclerosic lesions in arteries. Low and oscillatory (reversing in the axial flow direction) wall shear stress (WSS) induce inflammatory responses in endothelial cells (ECs) mediating disease localization. The objective of this study is to investigate computationally how the flow direction (reflected in WSS variation on the EC surface over time) influences the forces experienced by structural components of ECs that are believed to play important roles in mechanotransduction. A three-dimensional, multi-scale, multi-component, viscoelastic model of focally adhered ECs is developed, in which oscillatory WSS (reversing or non-reversing) parallel to the principal flow direction, or multi-directional oscillatory WSS with reversing axial and transverse components are applied over the EC surface. The computational model includes the glycocalyx layer, actin cortical layer, nucleus, cytoskeleton, focal adhesions (FAs), stress fibres and adherens junctions (ADJs). We show the distinct effects of atherogenic flow profiles (reversing unidirectional flow and reversing multi-directional flow) on subcellular structures relative to non-atherogenic flow (non-reversing flow). Reversing flow lowers stresses and strains due to viscoelastic effects, and multi-directional flow alters stress on the ADJs perpendicular to the axial flow direction. The simulations predict forces on integrins, ADJ filaments and other substructures in the range that activate mechanotransduction.
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Affiliation(s)
- Mahsa Dabagh
- Department of Biomedical Engineering, Duke University, Durham, NC, USA .,School of Energy Systems, Lappeenranta University of Technology, Lappeenranta, Finland
| | - Payman Jalali
- School of Energy Systems, Lappeenranta University of Technology, Lappeenranta, Finland
| | - Peter J Butler
- Department of Biomedical Engineering, The Pennsylvania State University, Pennsylvania, PA, USA
| | - Amanda Randles
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
| | - John M Tarbell
- Department of Biomedical Engineering, The City College of New York, New York, NY, USA
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11
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Zhao X, Palacci H, Yadav V, Spiering MM, Gilson MK, Butler PJ, Hess H, Benkovic SJ, Sen A. Substrate-driven chemotactic assembly in an enzyme cascade. Nat Chem 2017; 10:311-317. [DOI: 10.1038/nchem.2905] [Citation(s) in RCA: 98] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Accepted: 11/01/2017] [Indexed: 02/07/2023]
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12
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Tang X, Loc WS, Dong C, Matters GL, Butler PJ, Kester M, Meyers C, Jiang Y, Adair JH. The use of nanoparticulates to treat breast cancer. Nanomedicine (Lond) 2017; 12:2367-2388. [PMID: 28868970 DOI: 10.2217/nnm-2017-0202] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Breast cancer is a major ongoing public health issue among women in both developing and developed countries. Significant progress has been made to improve the breast cancer treatment in the past decades. However, the current clinical approaches are invasive, of low specificity and can generate severe side effects. As a rapidly developing field, nanotechnology brings promising opportunities to human cancer diagnosis and treatment. The use of nanoparticulate-based platforms overcomes biological barriers and allows prolonged blood circulation time, simultaneous tumor targeting and enhanced accumulation of drugs in tumors. Currently available and clinically applicable innovative nanoparticulate-based systems for breast cancer nanotherapies are discussed in this review.
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Affiliation(s)
- Xiaomeng Tang
- Department of Chemistry, Pennsylvania State University, University Park, PA 16802, USA.,Department of Materials Science & Engineering, Pennsylvania State University, University Park, PA 16802, USA
| | - Welley S Loc
- Department of Chemistry, Pennsylvania State University, University Park, PA 16802, USA.,Department of Materials Science & Engineering, Pennsylvania State University, University Park, PA 16802, USA
| | - Cheng Dong
- Department of Bioengineering, Pennsylvania State University, University Park, PA 16802, USA
| | - Gail L Matters
- Department of Biochemistry & Molecular Biology, Pennsylvania State University College of Medicine, Hershey, PA 17033, USA
| | - Peter J Butler
- Department of Bioengineering, Pennsylvania State University, University Park, PA 16802, USA
| | - Mark Kester
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Craig Meyers
- Department of Microbiology & Immunology, Pennsylvania State University College of Medicine, Hershey, PA 17033, USA
| | - Yixing Jiang
- Marlene & Stewart Greenebaum Cancer Center, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - James H Adair
- Department of Materials Science & Engineering, Pennsylvania State University, University Park, PA 16802, USA
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13
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Abstract
Colloidal suspensions containing microscopic swimmers have been the focus of recent studies aimed at understanding the principles of energy transfer in fluidic media at low Reynolds number conditions. Going down in scale, active enzymes have been shown to be force-generating, nonequilibrium systems, thus offering opportunity to examine energy transfer at the ultralow Reynolds number regime. By monitoring the change of diffusion of inert tracers dispersed in active enzyme solutions, we demonstrate that the nature of energy transfer in these systems is similar to that reported for larger microscopic active systems, despite the large differences in scale, modes of energy transduction, and propulsion. Additionally, even an enzyme that catalyzes an endothermic reaction behaves analogously, suggesting that heat generation is not the primary factor for the observed enhanced tracer diffusion. Our results provide new insights into the mechanism of energy transfer at the molecular level.
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Affiliation(s)
- Xi Zhao
- Department of Chemistry, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - Krishna K Dey
- Department of Physics, Indian Institute of Technology Gandhinagar , Palaj, Gandhinagar 382355, Gujarat, India
| | - Selva Jeganathan
- Department of Biomedical Engineering, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - Peter J Butler
- Department of Biomedical Engineering, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - Ubaldo M Córdova-Figueroa
- Department of Chemical Engineering, University of Puerto Rico-Mayagüez , Mayagüez, PR 00681, Puerto Rico, United States
| | - Ayusman Sen
- Department of Chemistry, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
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14
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Illien P, Zhao X, Dey KK, Butler PJ, Sen A, Golestanian R. Exothermicity Is Not a Necessary Condition for Enhanced Diffusion of Enzymes. Nano Lett 2017; 17:4415-4420. [PMID: 28593755 DOI: 10.1021/acs.nanolett.7b01502] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Recent experiments have revealed that the diffusivity of exothermic and fast enzymes is enhanced when they are catalytically active, and different physical mechanisms have been explored and quantified to account for this observation. We perform measurements on the endothermic and relatively slow enzyme aldolase, which also shows substrate-induced enhanced diffusion. We propose a new physical paradigm, which reveals that the diffusion coefficient of a model enzyme hydrodynamically coupled to its environment increases significantly when undergoing changes in conformational fluctuations in a substrate concentration dependent manner, and is independent of the overall turnover rate of the underlying enzymatic reaction. Our results show that substrate-induced enhanced diffusion of enzyme molecules can be explained within an equilibrium picture and that the exothermicity of the catalyzed reaction is not a necessary condition for the observation of this phenomenon.
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Affiliation(s)
- Pierre Illien
- Rudolf Peierls Centre for Theoretical Physics, University of Oxford , Oxford OX1 3NP, United Kingdom
| | | | | | | | | | - Ramin Golestanian
- Rudolf Peierls Centre for Theoretical Physics, University of Oxford , Oxford OX1 3NP, United Kingdom
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15
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Loc WS, Linton SS, Wilczynski ZR, Matters GL, McGovern CO, Abraham T, Fox T, Gigliotti CM, Tang X, Tabakovic A, Martin JA, Clawson GA, Smith JP, Butler PJ, Kester M, Adair JH. Effective encapsulation and biological activity of phosphorylated chemotherapeutics in calcium phosphosilicate nanoparticles for the treatment of pancreatic cancer. Nanomedicine 2017; 13:2313-2324. [PMID: 28673852 DOI: 10.1016/j.nano.2017.06.017] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Revised: 05/23/2017] [Accepted: 06/20/2017] [Indexed: 12/13/2022]
Abstract
Drug resistant cancers like pancreatic ductal adenocarcinoma (PDAC) are difficult to treat, and nanoparticle drug delivery systems can overcome some of the limitations of conventional systemic chemotherapy. In this study, we demonstrate that FdUMP and dFdCMP, the bioactive, phosphorylated metabolites of the chemotherapy drugs 5-FU and gemcitabine, can be encapsulated into calcium phosphosilicate nanoparticles (CPSNPs). The non-phosphorylated drug analogs were not well encapsulated by CPSNPs, suggesting the phosphate modification is essential for effective encapsulation. In vitro proliferation assays, cell cycle analyses and/or thymidylate synthase inhibition assays verified that CPSNP-encapsulated phospho-drugs retained biological activity. Analysis of orthotopic tumors from mice treated systemically with tumor-targeted FdUMP-CPSNPs confirmed the in vivo up take of these particles by PDAC tumor cells and release of active drug cargos intracellularly. These findings demonstrate a novel methodology to efficiently encapsulate chemotherapeutic agents into the CPSNPs and to effectively deliver them to pancreatic tumor cells.
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Affiliation(s)
- Welley S Loc
- Department of Chemistry, Pennsylvania State University, University Park, PA, USA; Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA, USA
| | - Samuel S Linton
- Department of Pharmacology, Pennsylvania State University College of Medicine, Hershey, PA, USA
| | - Zachary R Wilczynski
- Department of Biomedical Engineering/Bioengineering, Pennsylvania State University, University Park, PA, USA
| | - Gail L Matters
- Department of Biochemistry and Molecular Biology, Pennsylvania State University College of Medicine, Hershey, PA, USA
| | - Christopher O McGovern
- Department of Biochemistry and Molecular Biology, Pennsylvania State University College of Medicine, Hershey, PA, USA
| | - Thomas Abraham
- Department of Neural and Behavioral Sciences and the Microscopy Imaging Facility, Pennsylvania State University College of Medicine, Hershey, PA, USA
| | - Todd Fox
- Department of Pharmacology, University of Virginia, Charlottesville, VA, USA
| | - Christopher M Gigliotti
- Department of Biomedical Engineering/Bioengineering, Pennsylvania State University, University Park, PA, USA
| | - Xiaomeng Tang
- Department of Chemistry, Pennsylvania State University, University Park, PA, USA; Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA, USA
| | - Amra Tabakovic
- Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA, USA
| | - Jo Ann Martin
- Biomedical Engineering, University of Florida, Gainesville, FL, USA
| | - Gary A Clawson
- Department of Pathology and Gittlen Cancer Institute, Pennsylvania State University College of Medicine, Hershey, PA, USA
| | - Jill P Smith
- Department of Medicine, Georgetown University, Washington, DC, USA
| | - Peter J Butler
- Department of Biomedical Engineering/Bioengineering, Pennsylvania State University, University Park, PA, USA
| | - Mark Kester
- Department of Pharmacology, University of Virginia, Charlottesville, VA, USA
| | - James H Adair
- Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA, USA; Department of Pharmacology, Pennsylvania State University College of Medicine, Hershey, PA, USA; Department of Biomedical Engineering/Bioengineering, Pennsylvania State University, University Park, PA, USA.
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16
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Ren T, Erbakan M, Shen Y, Barbieri E, Saboe P, Feroz H, Yan H, McCuskey S, Hall JF, Schantz AB, Bazan GC, Butler PJ, Grzelakowski M, Kumar M. Membrane Protein Insertion into and Compatibility with Biomimetic Membranes. ACTA ACUST UNITED AC 2017; 1:e1700053. [DOI: 10.1002/adbi.201700053] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Revised: 05/07/2017] [Indexed: 11/12/2022]
Affiliation(s)
- Tingwei Ren
- Department of Chemical Engineering The Pennsylvania State University University Park PA 16802 USA
| | - Mustafa Erbakan
- Department of Chemical Engineering The Pennsylvania State University University Park PA 16802 USA
- Department of Biosystem Engineering Bozok University Yozgat 66000 Turkey
| | - Yuexiao Shen
- Department of Chemical Engineering The Pennsylvania State University University Park PA 16802 USA
| | - Eduardo Barbieri
- Department of Chemical Engineering The Pennsylvania State University University Park PA 16802 USA
- Departamento de Engenharia Química Universidade Federal do Rio de Janeiro Centro de Tecnologia Bloco E Rio de Janeiro RJ CEP 21941‐909 Brazil
| | - Patrick Saboe
- Department of Chemical Engineering The Pennsylvania State University University Park PA 16802 USA
| | - Hasin Feroz
- Department of Chemical Engineering The Pennsylvania State University University Park PA 16802 USA
| | - Hengjing Yan
- Department of Chemistry and Biochemistry University of California Santa Barbara CA 93106 USA
| | - Samantha McCuskey
- Department of Chemistry and Biochemistry University of California Santa Barbara CA 93106 USA
| | - Joseph F. Hall
- Department of Chemical Engineering The Pennsylvania State University University Park PA 16802 USA
| | - A. Benjamin Schantz
- Department of Chemical Engineering The Pennsylvania State University University Park PA 16802 USA
| | - Guillermo C. Bazan
- Department of Chemistry and Biochemistry University of California Santa Barbara CA 93106 USA
| | - Peter J. Butler
- Department of Biomedical Engineering The Pennsylvania State University University Park PA USA 16802
| | | | - Manish Kumar
- Department of Chemical Engineering The Pennsylvania State University University Park PA 16802 USA
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17
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Clawson GA, Abraham T, Pan W, Tang X, Linton SS, McGovern CO, Loc WS, Smith JP, Butler PJ, Kester M, Adair JH, Matters GL. A Cholecystokinin B Receptor-Specific DNA Aptamer for Targeting Pancreatic Ductal Adenocarcinoma. Nucleic Acid Ther 2016; 27:23-35. [PMID: 27754762 PMCID: PMC5312616 DOI: 10.1089/nat.2016.0621] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Pancreatic ductal adenocarcinomas (PDACs) constitutively express the G-protein-coupled cholecystokinin B receptor (CCKBR). In this study, we identified DNA aptamers (APs) that bind to the CCKBR and describe their characterization and targeting efficacy. Using dual SELEX selection against “exposed” CCKBR peptides and CCKBR-expressing PDAC cells, a pool of DNA APs was identified. Further downselection was based on predicted structures and properties, and we selected eight APs for initial characterizations. The APs bound specifically to the CCKBR, and we showed not only that they did not stimulate proliferation of PDAC cell lines but rather inhibited their proliferation. We chose one AP, termed AP1153, for further binding and localization studies. We found that AP1153 did not activate CCKBR signaling pathways, and three-dimensional Confocal microscopy showed that AP1153 was internalized by PDAC cells in a receptor-mediated manner. AP1153 showed a binding affinity of 15 pM. Bioconjugation of AP1153 to the surface of fluorescent NPs greatly facilitated delivery of NPs to PDAC tumors in vivo. The selectivity of this AP-targeted NP delivery system holds promise for enhanced early detection of PDAC lesions as well as improved chemotherapeutic treatments for PDAC patients.
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Affiliation(s)
- Gary A Clawson
- 1 Department of Pathology, Gittlen Cancer Research Laboratories, Pennsylvania State University College of Medicine , Hershey, Pennsylvania
| | - Thomas Abraham
- 2 Department of Neural and Behavioral Sciences and the Microscopy Imaging Facility, Pennsylvania State University College of Medicine , Hershey, Pennsylvania
| | - Weihua Pan
- 1 Department of Pathology, Gittlen Cancer Research Laboratories, Pennsylvania State University College of Medicine , Hershey, Pennsylvania
| | - Xiaomeng Tang
- 3 Department of Chemistry, Pennsylvania State University , University Park, Pennsylvania.,4 Department of Materials Science and Engineering, Pennsylvania State University , University Park, Pennsylvania
| | - Samuel S Linton
- 5 Department of Biochemistry and Molecular Biology, Pennsylvania State University College of Medicine , Hershey, Pennsylvania
| | - Christopher O McGovern
- 5 Department of Biochemistry and Molecular Biology, Pennsylvania State University College of Medicine , Hershey, Pennsylvania
| | - Welley S Loc
- 3 Department of Chemistry, Pennsylvania State University , University Park, Pennsylvania.,4 Department of Materials Science and Engineering, Pennsylvania State University , University Park, Pennsylvania
| | - Jill P Smith
- 6 Department of Medicine, Georgetown University , Washington, District of Columbia
| | - Peter J Butler
- 7 Department of Bioengineering, Pennsylvania State University , University Park, Pennsylvania
| | - Mark Kester
- 8 Department of Pharmacology, University of Virginia , Charlottesville, Virginia
| | - James H Adair
- 4 Department of Materials Science and Engineering, Pennsylvania State University , University Park, Pennsylvania
| | - Gail L Matters
- 5 Department of Biochemistry and Molecular Biology, Pennsylvania State University College of Medicine , Hershey, Pennsylvania
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18
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Eckman M, Gigliotti C, Sutermaster S, Butler PJ, Mehta K. Using handgrip strength to screen for diabetes in developing countries. J Med Eng Technol 2015; 40:8-14. [DOI: 10.3109/03091902.2015.1112855] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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19
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Abstract
Nature supports multifaceted forms of life. Despite the variety and complexity of these forms, motility remains the epicenter of life. The applicable laws of physics change upon going from macroscales to microscales and nanoscales, which are characterized by low Reynolds number (Re). We discuss motion at low Re in natural and synthetic systems, along with various propulsion mechanisms, including electrophoresis, electrolyte diffusiophoresis, and nonelectrolyte diffusiophoresis. We also describe the newly uncovered phenomena of motility in non-ATP-driven self-powered enzymes and the directional movement of these enzymes in response to substrate gradients. These enzymes can also be immobilized to function as fluid pumps in response to the presence of their substrates. Finally, we review emergent collective behavior arising from interacting motile species, and we discuss the possible biomedical applications of the synthetic nanobots and microbots.
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Affiliation(s)
| | | | - Peter J. Butler
- Department of Biomedical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802;,
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20
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Huang C, Ozdemir T, Xu LC, Butler PJ, Siedlecki CA, Brown JL, Zhang S. The role of substrate topography on the cellular uptake of nanoparticles. J Biomed Mater Res B Appl Biomater 2015; 104:488-95. [PMID: 25939598 DOI: 10.1002/jbm.b.33397] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2014] [Revised: 01/15/2015] [Accepted: 02/08/2015] [Indexed: 12/12/2022]
Abstract
Improving targeting efficacy has been a central focus of the studies on nanoparticle (NP)-based drug delivery nanocarriers over the past decades. As cells actively sense and respond to the local physical environments, not only the NP design (e.g., size, shape, ligand density, etc.) but also the cell mechanics (e.g., stiffness, spreading, expressed receptors, etc.) affect the cellular uptake efficiency. While much work has been done to elucidate the roles of NP design for cells seeded on a flat tissue culture surface, how the local physical environments of cells mediate uptake of NPs remains unexplored, despite the widely known effect of local physical environments on cellular responses in vitro and disease states in vivo. Here, we report the active responses of human osteosarcoma cells to fibrous substrate topographies and the subsequent changes in the cellular uptake of NPs. Our experiments demonstrate that surface topography modulates cellular uptake efficacy by mediating cell spreading and membrane mechanics. The findings provide a concrete example of the regulative role of the physical environments of cells on cellular uptake of NPs, therefore advancing the rational design of NPs for enhanced drug delivery in targeted cancer therapy.
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Affiliation(s)
- Changjin Huang
- Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, Pennsylvania, 16802
| | - Tugba Ozdemir
- Department of Bioengineering, The Pennsylvania State University, University Park, Pennsylvania, 16802
| | - Li-Chong Xu
- Department of Surgery, The Pennsylvania State University, College of Medicine, Hershey, Pennsylvania, 17033
| | - Peter J Butler
- Department of Bioengineering, The Pennsylvania State University, University Park, Pennsylvania, 16802
| | - Christopher A Siedlecki
- Department of Bioengineering, The Pennsylvania State University, University Park, Pennsylvania, 16802.,Department of Surgery, The Pennsylvania State University, College of Medicine, Hershey, Pennsylvania, 17033
| | - Justin L Brown
- Department of Bioengineering, The Pennsylvania State University, University Park, Pennsylvania, 16802
| | - Sulin Zhang
- Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, Pennsylvania, 16802.,Department of Bioengineering, The Pennsylvania State University, University Park, Pennsylvania, 16802
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21
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Dabagh M, Jalali P, Butler PJ, Tarbell JM. Shear-induced force transmission in a multicomponent, multicell model of the endothelium. J R Soc Interface 2015; 11:20140431. [PMID: 24966239 DOI: 10.1098/rsif.2014.0431] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Haemodynamic forces applied at the apical surface of vascular endothelial cells (ECs) provide the mechanical signals at intracellular organelles and through the inter-connected cellular network. The objective of this study is to quantify the intracellular and intercellular stresses in a confluent vascular EC monolayer. A novel three-dimensional, multiscale and multicomponent model of focally adhered ECs is developed to account for the role of potential mechanosensors (glycocalyx layer, actin cortical layer, nucleus, cytoskeleton, focal adhesions (FAs) and adherens junctions (ADJs)) in mechanotransmission and EC deformation. The overriding issue addressed is the stress amplification in these regions, which may play a role in subcellular localization of mechanotransmission. The model predicts that the stresses are amplified 250-600-fold over apical values at ADJs and 175-200-fold at FAs for ECs exposed to a mean shear stress of 10 dyne cm(-2). Estimates of forces per molecule in the cell attachment points to the external cellular matrix and cell-cell adhesion points are of the order of 8 pN at FAs and as high as 3 pN at ADJs, suggesting that direct force-induced mechanotransmission by single molecules is possible in both. The maximum deformation of an EC in the monolayer is calculated as 400 nm in response to a mean shear stress of 1 Pa applied over the EC surface which is in accord with measurements. The model also predicts that the magnitude of the cell-cell junction inclination angle is independent of the cytoskeleton and glycocalyx. The inclination angle of the cell-cell junction is calculated to be 6.6° in an EC monolayer, which is somewhat below the measured value (9.9°) reported previously for ECs subjected to 1.6 Pa shear stress for 30 min. The present model is able, for the first time, to cross the boundaries between different length scales in order to provide a global view of potential locations of mechanotransmission.
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Affiliation(s)
- Mahsa Dabagh
- School of Technology, Lappeenranta University of Technology, Lappeenranta, Finland
| | - Payman Jalali
- School of Technology, Lappeenranta University of Technology, Lappeenranta, Finland
| | - Peter J Butler
- Department of Biomedical Engineering, The Pennsylvania State University, Pennsylvania, PA, USA
| | - John M Tarbell
- Department of Biomedical Engineering, The City College of New York, New York, USA
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22
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Bishop CM, Spivey RJ, Hawkes LA, Batbayar N, Chua B, Frappell PB, Milsom WK, Natsagdorj T, Newman SH, Scott GR, Takekawa JY, Wikelski M, Butler PJ. The roller coaster flight strategy of bar-headed geese conserves energy during Himalayan migrations. Science 2015; 347:250-4. [PMID: 25593180 DOI: 10.1126/science.1258732] [Citation(s) in RCA: 145] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The physiological and biomechanical requirements of flight at high altitude have been the subject of much interest. Here, we uncover a steep relation between heart rate and wingbeat frequency (raised to the exponent 3.5) and estimated metabolic power and wingbeat frequency (exponent 7) of migratory bar-headed geese. Flight costs increase more rapidly than anticipated as air density declines, which overturns prevailing expectations that this species should maintain high-altitude flight when traversing the Himalayas. Instead, a "roller coaster" strategy, of tracking the underlying terrain and discarding large altitude gains only to recoup them later in the flight with occasional benefits from orographic lift, is shown to be energetically advantageous for flights over the Himalayas.
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Affiliation(s)
- C M Bishop
- School of Biological Sciences, Bangor University, Bangor, Gwynedd, UK
| | - R J Spivey
- School of Biological Sciences, Bangor University, Bangor, Gwynedd, UK
| | - L A Hawkes
- School of Biological Sciences, Bangor University, Bangor, Gwynedd, UK.
| | - N Batbayar
- Wildlife Science and Conservation Center of Mongolia, Ulaanbataar, Mongolia
| | - B Chua
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
| | - P B Frappell
- Office of the Dean of Graduate Research, University of Tasmania, Tasmania, Australia
| | - W K Milsom
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
| | - T Natsagdorj
- Mongolian Academy of Sciences, Ulaanbataar, Mongolia
| | - S H Newman
- Emergency Prevention System(EMPRES) Wildlife and Ecology Unit, Food and Agriculture Organization of the United Nations (FAO), Rome, Italy
| | - G R Scott
- Department of Biology, McMaster University, Ontario, Ontario, Canada
| | - J Y Takekawa
- San Francisco Bay Estuary Field Station, Western Ecological Research Center, U.S. Geological Survey, Vallejo, CA 94592 USA
| | - M Wikelski
- Max Planck Institüt für Ornithologie, Radolfzell, Germany. Department of Biology, University of Konstanz, Konstanz, Germany
| | - P J Butler
- School of Biosciences, University of Birmingham, Birmingham, UK
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23
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Abstract
We review studies that quantify newly discovered forces from single enzymatic reactions. These forces arise from the conversion of chemical energy to kinetic energy, which can be harnessed to direct diffusion of the enzyme up a concentration gradient of substrate, a novel phenomenon of molecular chemotaxis. When immobilized, enzymes can move fluid around them and perform directional pumping in microfluidic chambers. Because of the extensive array of enzymes in biological cells, we also develop three new hypotheses: that enzymatic self diffusion can assist in organizing signaling pathways in cells, can assist in pumping of fluid in cells, and can impose biologically significant forces on organelles, which will be manifested as stochastic motion not explained by thermal forces or myosin II. Such mechanochemical phenomena open up new directions in research in mechanobiology in which all enzymes, in addition to their primary function as catalysts for reactions, may have secondary functions as initiators of mechanosensitive transduction pathways.
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Affiliation(s)
- Peter J Butler
- Department of Biomedical Engineering, The Pennsylvania State University, 205 Hallowell Building, University Park, PA 16802, USA
| | - Krishna K Dey
- Department of Chemistry, The Pennsylvania State University, 104 Chemistry Building, University Park, PA 16802, USA
| | - Ayusman Sen
- Department of Chemistry, The Pennsylvania State University, 104 Chemistry Building, University Park, PA 16802, USA
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24
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Abstract
We demonstrate a procedure for the separation of enzymes based on their chemotactic response toward an imposed substrate concentration gradient. The separation is observed within a two-inlet, five-outlet microfluidic network, designed to allow mixtures of active (ones that catalyze substrate turnover) and inactive (ones that do not catalyze substrate turnover) enzymes, labeled with different fluorophores, to flow through one of the inlets. Substrate solution prepared in phosphate buffer was introduced through the other inlet of the device at the same flow rate. The steady-state concentration profiles of the enzymes were obtained at specific positions within the outlets of the microchannel using fluorescence microscopy. In the presence of a substrate concentration gradient, active enzyme molecules migrated preferentially toward the substrate channel. The excess migration of the active enzyme molecules was quantified in terms of an enrichment coefficient. Experiments were carried out with different pairs of enzymes. Coupling the physics of laminar flow of liquid and molecular diffusion, multiphysics simulations were carried out to estimate the extent of the chemotactic separation. Our results show that, with appropriate microfluidic arrangement, molecular chemotaxis leads to spontaneous separation of active enzyme molecules from their inactive counterparts of similar charge and size.
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Affiliation(s)
- Krishna Kanti Dey
- Department of Chemistry, ‡Department of Biomedical Engineering, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
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25
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Ahmed D, Muddana HS, Lu M, French JB, Ozcelik A, Fang Y, Butler PJ, Benkovic SJ, Manz A, Huang TJ. Acoustofluidic chemical waveform generator and switch. Anal Chem 2014; 86:11803-10. [PMID: 25405550 PMCID: PMC4255676 DOI: 10.1021/ac5033676] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Eliciting a cellular response to a changing chemical microenvironment is central to many biological processes including gene expression, cell migration, differentiation, apoptosis, and intercellular signaling. The nature and scope of the response is highly dependent upon the spatiotemporal characteristics of the stimulus. To date, studies that investigate this phenomenon have been limited to digital (or step) chemical stimulation with little control over the temporal counterparts. Here, we demonstrate an acoustofluidic (i.e., fusion of acoustics and microfluidics) approach for generating programmable chemical waveforms that permits continuous modulation of the signal characteristics including the amplitude (i.e., sample concentration), shape, frequency, and duty cycle, with frequencies reaching up to 30 Hz. Furthermore, we show fast switching between multiple distinct stimuli, wherein the waveform of each stimulus is independently controlled. Using our device, we characterized the frequency-dependent activation and internalization of the β2-adrenergic receptor (β2-AR), a prototypic G-protein coupled receptor (GPCR), using epinephrine. The acoustofluidic-based programmable chemical waveform generation and switching method presented herein is expected to be a powerful tool for the investigation and characterization of the kinetics and other dynamic properties of many biological and biochemical processes.
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Affiliation(s)
- Daniel Ahmed
- Department of Engineering Science and Mechanics, ‡Biomedical Engineering, §Department of Chemistry, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
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26
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Sengupta S, Spiering MM, Dey KK, Duan W, Patra D, Butler PJ, Astumian RD, Benkovic SJ, Sen A. DNA polymerase as a molecular motor and pump. ACS Nano 2014; 8:2410-2418. [PMID: 24601532 DOI: 10.1021/nn405963x] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
DNA polymerase is responsible for synthesizing DNA, a key component in the running of biological machinery. Using fluorescence correlation spectroscopy, we demonstrate that the diffusive movement of a molecular complex of DNA template and DNA polymerase enhances during nucleotide incorporation into the growing DNA template. The diffusion coefficient of the complex also shows a strong dependence on its inorganic cofactor, Mg2+ ions. When exposed to gradients of either nucleotide or cofactor concentrations, an ensemble of DNA polymerase complex molecules shows collective movement toward regions of higher concentrations. By immobilizing the molecular complex on a patterned gold surface, we demonstrate the fabrication of DNA polymerase-powered fluid pumps. These miniature pumps are capable of transporting fluid and tracer particles in a directional manner with the pumping speed increasing in the presence of the cofactor. The role of DNA polymerase as a micropump opens up avenues for designing miniature fluid pumps using enzymes as engines.
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Affiliation(s)
- Samudra Sengupta
- Department of Chemistry and ‡Department of Bioengineering, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
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27
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Erbakan M, Shen YX, Grzelakowski M, Butler PJ, Kumar M, Curtis WR. Molecular cloning, overexpression and characterization of a novel water channel protein from Rhodobacter sphaeroides. PLoS One 2014; 9:e86830. [PMID: 24497982 PMCID: PMC3909002 DOI: 10.1371/journal.pone.0086830] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2013] [Accepted: 12/14/2013] [Indexed: 11/19/2022] Open
Abstract
Aquaporins are highly selective water channel proteins integrated into plasma membranes of single cell organisms; plant roots and stromae; eye lenses, renal and red blood cells in vertebrates. To date, only a few microbial aquaporins have been characterized and their physiological importance is not well understood. Here we report on the cloning, expression and characterization of a novel aquaporin, RsAqpZ, from a purple photosynthetic bacterium, Rhodobacter sphaeroides ATCC 17023. The protein was expressed homologously at a high yield (∼20 mg/L culture) under anaerobic photoheterotrophic growth conditions. Stopped-flow light scattering experiments demonstrated its high water permeability (0.17±0.05 cm/s) and low energy of activation for water transport (2.93±0.60 kcal/mol) in reconstituted proteoliposomes at a protein to lipid ratio (w/w) of 0.04. We developed a fluorescence correlation spectroscopy based technique and utilized a fluorescent protein fusion of RsAqpZ, to estimate the single channel water permeability of RsAqpZ as 1.24 (±0.41) x 10(-12) cm(3)/s or 4.17 (±1.38)×10(10) H2O molecules/s, which is among the highest single channel permeability reported for aquaporins. Towards application to water purification technologies, we also demonstrated functional incorporation of RsAqpZ in amphiphilic block copolymer membranes.
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Affiliation(s)
- Mustafa Erbakan
- Department of Biomedical Engineering, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Yue-xiao Shen
- Department of Chemical Engineering, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | | | - Peter J. Butler
- Department of Biomedical Engineering, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Manish Kumar
- Department of Chemical Engineering, Pennsylvania State University, University Park, Pennsylvania, United States of America
- * E-mail: (MK); (WRC)
| | - Wayne R. Curtis
- Department of Biomedical Engineering, Pennsylvania State University, University Park, Pennsylvania, United States of America
- Department of Chemical Engineering, Pennsylvania State University, University Park, Pennsylvania, United States of America
- * E-mail: (MK); (WRC)
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28
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Abstract
Nanoparticle (NP)-bioconjugates hold great promise for more sensitive disease diagnosis and more effective anticancer drug delivery compared with existing approaches. A critical aspect in both applications is cellular internalization of NPs, which is influenced by NP properties and cell surface mechanics. Despite considerable progress in optimization of the NP-bioconjugates for improved targeting, the role of substrate stiffness on cellular uptake has not been investigated. Using polyacrylamide (PA) hydrogels as model substrates with tunable stiffness, we quantified the relationship between substrate stiffness and cellular uptake of fluorescent NPs by bovine aortic endothelial cells (BAECs). We found that a stiffer substrate results in a higher total cellular uptake on a per cell basis, but a lower uptake per unit membrane area. To obtain a mechanistic understanding of the cellular uptake behavior, we developed a thermodynamic model that predicts that membrane spreading area and cell membrane tension are two key factors controlling cellular uptake of NPs, both of which are modulated by substrate stiffness. Our experimental and modeling results not only open up new avenues for engineering NP-based cancer cell targets for more effective in vivo delivery but also contribute an example of how the physical environment dictates cellular behavior and function.
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Affiliation(s)
- Changjin Huang
- Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
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29
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Abstract
Using fluorescence correlation spectroscopy, we show that the diffusive movements of catalase enzyme molecules increase in the presence of the substrate, hydrogen peroxide, in a concentration-dependent manner. Employing a microfluidic device to generate a substrate concentration gradient, we show that both catalase and urease enzyme molecules spread toward areas of higher substrate concentration, a form of chemotaxis at the molecular scale. Using glucose oxidase and glucose to generate a hydrogen peroxide gradient, we induce the migration of catalase toward glucose oxidase, thereby showing that chemically interconnected enzymes can be drawn together.
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Affiliation(s)
- Samudra Sengupta
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
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30
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Hawkes LA, Balachandran S, Batbayar N, Butler PJ, Chua B, Douglas DC, Frappell PB, Hou Y, Milsom WK, Newman SH, Prosser DJ, Sathiyaselvam P, Scott GR, Takekawa JY, Natsagdorj T, Wikelski M, Witt MJ, Yan B, Bishop CM. The paradox of extreme high-altitude migration in bar-headed geese Anser indicus. Proc Biol Sci 2012; 280:20122114. [PMID: 23118436 DOI: 10.1098/rspb.2012.2114] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Bar-headed geese are renowned for migratory flights at extremely high altitudes over the world's tallest mountains, the Himalayas, where partial pressure of oxygen is dramatically reduced while flight costs, in terms of rate of oxygen consumption, are greatly increased. Such a mismatch is paradoxical, and it is not clear why geese might fly higher than is absolutely necessary. In addition, direct empirical measurements of high-altitude flight are lacking. We test whether migrating bar-headed geese actually minimize flight altitude and make use of favourable winds to reduce flight costs. By tracking 91 geese, we show that these birds typically travel through the valleys of the Himalayas and not over the summits. We report maximum flight altitudes of 7290 m and 6540 m for southbound and northbound geese, respectively, but with 95 per cent of locations received from less than 5489 m. Geese travelled along a route that was 112 km longer than the great circle (shortest distance) route, with transit ground speeds suggesting that they rarely profited from tailwinds. Bar-headed geese from these eastern populations generally travel only as high as the terrain beneath them dictates and rarely in profitable winds. Nevertheless, their migration represents an enormous challenge in conditions where humans and other mammals are only able to operate at levels well below their sea-level maxima.
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Affiliation(s)
- L A Hawkes
- School of Biological Sciences, University of Bangor, Deiniol Road, Bangor, Gwynedd LL57 2UW, UK
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Abstract
Endothelial cells sense mechanical forces of blood flow through mechanisms that involve focal adhesions (FAs). The mechanosensitive pathways that originate from FA-associated integrin activation may involve membrane rafts, small cholesterol- and sphigolipid-rich domains that are either immobilized, by virtue of their attachment to the cytoskeleton, or highly mobile in the plane of the plasma membrane. In this study, we fluorescently labeled non-mobile and mobile populations of GM1, a ganglioside associated with lipid rafts, and transfected cells with the red fluorescent protein-(RFP-) talin, an indicator of integrin activation at FAs, in order to determine the kinetics and sequential order of raft and talin mechanosensitivity. Cells were imaged under confocal microscopy during mechanical manipulation of a FA induced by a fibronectin (FN)-functionalized nanoelectrode with feedback control of position. First, FA deformation led to long range deformation of immobile rafts followed by active recoil of a subpopulation of displaced rafts. Second, initial adhesion between the FN-probe and the cell induced rapid accumulation of GM1 at the probe site with a time constant of 1.7 s. Talin accumulated approximately 20 s later with a time constant of 0.6 s. Third, a 1 μm deformation of the FA lead to immediate (0.3 s) increase in GM1 fluorescence and a later (6 s) increase in talin. Fourth, long term deformation of FAs led to continual GM1 accumulation at the probe site that was reversed upon removal of the deformation. These results demonstrate that rafts are directly mechanosensitive and that raft mobility may enable the earliest events related to FA mechanosensing and reinforcement upon force application.
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Affiliation(s)
- Daniela E Fuentes
- Department of Bioengineering, The Pennsylvania State University, 205 Hallowell Building, University Park, PA 16802, USA
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Muddana HS, Chiang HH, Butler PJ. Tuning membrane phase separation using nonlipid amphiphiles. Biophys J 2012; 102:489-97. [PMID: 22325271 DOI: 10.1016/j.bpj.2011.12.033] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2011] [Revised: 12/14/2011] [Accepted: 12/19/2011] [Indexed: 01/25/2023] Open
Abstract
Lipid phase separation may be a mechanism by which lipids participate in sorting membrane proteins and facilitate membrane-mediated biochemical signaling in cells. To provide new tools for membrane lipid phase manipulation that avoid direct effects on protein activity and lipid composition, we studied phase separation in binary and ternary lipid mixtures under the influence of three nonlipid amphiphiles, vitamin E (VE), Triton-X (TX)-100, and benzyl alcohol (BA). Mechanisms of additive-induced phase separation were elucidated using coarse-grained molecular dynamics simulations of these additives in a liquid bilayer made from 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and 1,2-dilinoleoyl-sn-glycero-3-phosphocholine [corrected]. From simulations, the additive's partitioning preference, changes in membrane thickness, and alterations in lipid order were quantified. Simulations showed that VE favored the DPPC phase but partitioned predominantly to the domain boundaries and lowered the tendency for domain formation, and therefore acted as a linactant. This simulated behavior was consistent with experimental observations in which VE promoted lipid mixing and dispersed domains in both gel/liquid and liquid-ordered/liquid-disordered systems. From simulation, BA partitioned predominantly to the DUPC phase, decreased lipid order there, and thinned the membrane. These actions explain why, experimentally, BA promoted phase separation in both binary and ternary lipid mixtures. In contrast, TX, a popular detergent used to isolate raft membranes in cells, exhibited equal preference for both phases, as demonstrated by simulations, but nonetheless, was a strong domain promoter in all lipid mixtures. Further analysis showed that TX increased membrane thickness of the DPPC phase to a greater extent than the DUPC phase and thus increased hydrophobic mismatch, which may explain experimental observation of phase separation in the presence of TX. In summary, these nonlipid amphiphiles provide new tools to tune domain formation in model vesicle systems and could provide the means to form or disperse membrane lipid domains in cells, in addition to the well-known methods involving cholesterol enrichment and sequestration.
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Affiliation(s)
- Hari S Muddana
- Department of Bioengineering, The Pennsylvania State University, University Park, Pennsylvania, USA
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Halsey LG, White CR, Enstipp MR, Wilson RP, Butler PJ, Martin GR, Grémillet D, Jones DR. Assessing the validity of the accelerometry technique for estimating the energy expenditure of diving double-crested cormorants Phalacrocorax auritus. Physiol Biochem Zool 2011; 84:230-7. [PMID: 21460533 DOI: 10.1086/658636] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Over the past few years, acceleration-data loggers have been used to provide calibrated proxies of energy expenditure: the accelerometry technique. Relationships between rate of oxygen consumption and a derivation of acceleration data termed "overall dynamic body acceleration" (ODBA) have now been generated for a range of species, including birds, mammals, and amphibians. In this study, we examine the utility of the accelerometry technique for estimating the energy expended by double-crested cormorants Phalacrocorax auritus to undertake a dive cycle (i.e., a dive and the subsequent pause at the surface before another dive). The results show that ODBA does not calibrate with energy expenditure in diving cormorants, where energy expenditure is calculated from measures of oxygen uptake during surface periods between dives. The possible explanations include reasons why energy expenditure may not relate to ODBA but also reasons why oxygen uptake between dives may not accurately represent energy expenditure during a dive cycle.
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Affiliation(s)
- L G Halsey
- Roehampton University, London SW15 4JD, UK.
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Butler PJ, Muddana HS, Chiang H. Enthalpy Drives Phase Separation in Model Membranes: Evidence from Molecular Dynamics Simulations of Non-Lipid Amphiphiles Vitamin-E, triton-X, and Benzyl Alcohol. Biophys J 2011. [DOI: 10.1016/j.bpj.2010.12.2891] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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Muddana HS, Gullapalli RR, Manias E, Butler PJ. Atomistic simulation of lipid and DiI dynamics in membrane bilayers under tension. Phys Chem Chem Phys 2010; 13:1368-78. [PMID: 21152516 DOI: 10.1039/c0cp00430h] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Membrane tension modulates cellular processes by initiating changes in the dynamics of its molecular constituents. To quantify the precise relationship between tension, structural properties of the membrane, and the dynamics of lipids and a lipophilic reporter dye, we performed atomistic molecular dynamics (MD) simulations of DiI-labeled dipalmitoylphosphatidylcholine (DPPC) lipid bilayers under physiological lateral tensions ranging from -2.6 mN m(-1) to 15.9 mN m(-1). Simulations showed that the bilayer thickness decreased linearly with tension consistent with volume-incompressibility, and this thinning was facilitated by a significant increase in acyl chain interdigitation at the bilayer midplane and spreading of the acyl chains. Tension caused a significant drop in the bilayer's peak electrostatic potential, which correlated with the strong reordering of water and lipid dipoles. For the low tension regime, the DPPC lateral diffusion coefficient increased with increasing tension in accordance with free-area theory. For larger tensions, free area theory broke down due to tension-induced changes in molecular shape and friction. Simulated DiI rotational and lateral diffusion coefficients were lower than those of DPPC but increased with tension in a manner similar to DPPC. Direct correlation of membrane order and viscosity near the DiI chromophore, which was just under the DPPC headgroup, indicated that measured DiI fluorescence lifetime, which is reported to decrease with decreasing lipid order, is likely to be a good reporter of tension-induced decreases in lipid headgroup viscosity. Together, these results offer new molecular-level insights into membrane tension-related mechanotransduction and into the utility of DiI in characterizing tension-induced changes in lipid packing.
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Affiliation(s)
- Hari S Muddana
- Department of Bioengineering, The Pennsylvania State University, 230 Hallowell Building, University Park, PA, USA
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Bourouiba L, Wu J, Newman S, Takekawa J, Natdorj T, Batbayar N, Bishop CM, Hawkes LA, Butler PJ, Wikelski M. Spatial dynamics of bar-headed geese migration in the context of H5N1. J R Soc Interface 2010; 7:1627-39. [PMID: 20472636 PMCID: PMC2988256 DOI: 10.1098/rsif.2010.0126] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2010] [Accepted: 04/21/2010] [Indexed: 11/12/2022] Open
Abstract
Virulent outbreaks of highly pathogenic avian influenza (HPAI) since 2005 have raised the question about the roles of migratory and wild birds in the transmission of HPAI. Despite increased monitoring, the role of wild waterfowl as the primary source of the highly pathogenic H5N1 has not been clearly established. The impact of outbreaks of HPAI among species of wild birds which are already endangered can nevertheless have devastating consequences for the local and non-local ecology where migratory species are established. Understanding the entangled dynamics of migration and the disease dynamics will be key to prevention and control measures for humans, migratory birds and poultry. Here, we present a spatial dynamic model of seasonal migration derived from first principles and linking the local dynamics during migratory stopovers to the larger scale migratory routes. We discuss the effect of repeated epizootic at specific migratory stopovers for bar-headed geese (Anser indicus). We find that repeated deadly outbreaks of H5N1 on stopovers during the autumn migration of bar-headed geese could lead to a larger reduction in the size of the equilibrium bird population compared with that obtained after repeated outbreaks during the spring migration. However, the opposite is true during the first few years of transition to such an equilibrium. The age-maturation process of juvenile birds which are more susceptible to H5N1 reinforces this result.
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Affiliation(s)
- L Bourouiba
- Department of Mathematics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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38
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Abstract
Blood flow-associated shear stress causes physiological and pathophysiological biochemical processes in endothelial cells that may be initiated by alterations in plasma membrane lipid domains characterized as liquid-ordered (l(o)), such as rafts or caveolae, or liquid-disordered (l(d)). To test for domain-dependent shear sensitivity, we used time-correlated single photon counting instrumentation to assess the photophysics and dynamics of the domain-selective lipid analogues DiI-C(12) and DiI-C(18) in endothelial cells subjected to physiological fluid shear stress. Under static conditions, DiI-C(12) fluorescence lifetime was less than DiI-C(18) lifetime and the diffusion coefficient of DiI-C(12) was greater than the DiI-C(18) diffusion coefficient, confirming that DiI-C(12) probes l(d), a more fluid membrane environment, and DiI-C(18) probes the l(o) phase. Domains probed by DiI-C(12) exhibited an early (10 s) and transient decrease of fluorescence lifetime after the onset of shear while domains probed by DiI-C(18) exhibited a delayed decrease of fluorescence lifetime that was sustained for the 2 min the cells were subjected to flow. The diffusion coefficient of DiI-C(18) increased after shear imposition, while that of DiI-C(12) remained constant. Determination of the number of molecules (N) in the control volume suggested that DiI-C(12)-labeled domains increased in N immediately after step-shear, while N for DiI-C(18)-stained membrane transiently decreased. These results demonstrate that membrane microdomains are differentially sensitive to fluid shear stress.
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Affiliation(s)
- Tristan Tabouillot
- Department of Bioengineering, The Pennsylvania State University, 205 Hallowell Building, University Park, PA 16802, USA
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Butler PJ, Kühlbrandt W. Determination of the aggregate size in detergent solution of the light-harvesting chlorophyll a/b-protein complex from chloroplast membranes. Proc Natl Acad Sci U S A 2010; 85:3797-801. [PMID: 16593931 PMCID: PMC280306 DOI: 10.1073/pnas.85.11.3797] [Citation(s) in RCA: 93] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The molecular mass of an oligomeric integral membrane protein, the light-harvesting chlorophyll a/b-protein complex from the photosynthetic membranes of chloroplasts, has been determined in detergent solution by analytical ultracentrifugation and measurement of the density increment at constant chemical potential of all diffusible solutes. The technique used eliminates any problems resulting from detergent binding to the protein, is independent of the particular detergent used (in this case the nonionic n-octyl beta-D-glucopyranoside), and gives the apparent weight-average molecular mass at different protein concentrations, allowing extrapolation to zero concentration. It means that the solutions of the complex must be brought to dialysis equilibrium with the solvent detergent solution and also requires a reliable method for measuring the protein concentration, for which amino acid analysis was used. The detergent-solubilized complex was a trimer that dissociated into monomers and dimers at low protein concentration. The accurate concentration determinations also allowed the molar chlorophyll-to-protein ratio to be measured as 15, corresponding to 8 chlorophyll a and 7 chlorophyll b molecules.
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Affiliation(s)
- P J Butler
- Medical Research Council Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, England
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Abstract
We show that diffusion of single urease enzyme molecules increases in the presence of urea in a concentration-dependent manner and calculate the force responsible for this increase. Urease diffusion measured using fluorescence correlation spectroscopy increased by 16-28% over buffer controls at urea concentrations ranging from 0.001 to 1 M. This increase was significantly attenuated when urease was inhibited with pyrocatechol, demonstrating that the increase in diffusion was the result of enzyme catalysis of urea. Local molecular pH changes as measured using the pH-dependent fluorescence lifetime of SNARF-1 conjugated to urease were not sufficient to explain the increase in diffusion. Thus, a force generated by self-electrophoresis remains the most plausible explanation. This force, evaluated using Brownian dynamics simulations, was 12 pN per reaction turnover. These measurements demonstrate force generation by a single enzyme molecule and lay the foundation for a further understanding of biological force generation and the development of enzyme-driven nanomotors.
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Affiliation(s)
- Hari S Muddana
- Departments of Bioengineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
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Abstract
Progress toward clinical application of biodegradable fluorescent calcium phosphate (CP) nanoparticles as a bioimaging agent requires detailed knowledge of chromophore interaction with CP. As readouts of this cargo-matrix interaction, we determined the principle photophysical properties of Cy3 encapsulated in CP nanparticles (CPNPs) using steady-state and time-resolved fluorescence spectroscopy. Fluorescence correlation spectroscopy (FCS)-determined diffusion coefficients and associated hydrodynamic radii confirmed the presence of highly monodisperse CPNPs with radii ranging from 7 to 10 nm. Single CP nanoparticles were 20 times brighter than free dye molecules because of a CP-induced 5-fold increase in quantum efficiency and encapsulation of four dye molecules per particle. Solvatochromic shifts resulting from hydrogen bonding between free dye and solvent or restricted intramolecular mobility by solvent viscosity were absent when Cy3 was encapsulated in CP. Encapsulation-mediated increases in radiative decay rates and decreases in nonradiative decay rates resulting in longer fluorescence lifetimes of Cy3 were attributed to solvent and CP-related local refractive indices and restricted flexibility of dye by rigid CP. Enhanced brightness of CPNPs enabled imaging of single nanoparticles under epifluorescence using both standard and total internal reflection fluorescence (TIRF) modes with camera exposure times on the order of tens of milliseconds. These enhanced photophysical properties together with excellent biocompatibility make CPNPs ideal for bioimaging applications ranging from single-molecule tracking to in vivo tumor detection and offer the possibility of timed codelivery of drugs to control cell function.
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Affiliation(s)
- Hari S. Muddana
- Department of Bioengineering, The Pennsylvania State University, 205 Hallowell Building, University Park, Pennsylvania 16802
| | - Thomas T. Morgan
- Department of Chemistry, The Pennsylvania State University, 249 Materials Research Laboratory, Hastings Road, University Park, Pennsylvania 16802
| | - James H. Adair
- Department of Materials Science and Engineering, The Pennsylvania State University, 249 Materials Research Laboratory, Hastings Road, University Park, Pennsylvania 16802
| | - Peter J. Butler
- Department of Bioengineering, The Pennsylvania State University, 205 Hallowell Building, University Park, Pennsylvania 16802
- mail correspondence to:
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Muddana HS, Morgan TT, Tabouillot T, Altinoglu EI, Adair JH, Butler PJ. Photophysical characterization of Dye-Encapsulated Calcium Phosphate Nanoparticles. Biophys J 2009. [DOI: 10.1016/j.bpj.2008.12.2035] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
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Bae C, Butler PJ. Assessing the Dynamics and Mechanics of the Cell Membrane. Biophys J 2009. [DOI: 10.1016/j.bpj.2008.12.3324] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
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Morgan TT, Muddana HS, Altinoǧlu EI, Rouse SM, Tabaković A, Tabouillot T, Russin TJ, Shanmugavelandy SS, Butler PJ, Eklund PC, Yun JK, Kester M, Adair JH. Encapsulation of organic molecules in calcium phosphate nanocomposite particles for intracellular imaging and drug delivery. Nano Lett 2008; 8:4108-15. [PMID: 19367837 PMCID: PMC3267632 DOI: 10.1021/nl8019888] [Citation(s) in RCA: 153] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Encapsulation of imaging agents and drugs in calcium phosphate nanoparticles (CPNPs) has potential as a nontoxic, bioresorbable vehicle for drug delivery to cells and tumors. The objectives of this study were to develop a calcium phosphate nanoparticle encapsulation system for organic dyes and therapeutic drugs so that advanced fluoresence methods could be used to assess the efficiency of drug delivery and possible mechanisms of nanoparticle bioabsorption. Highly concentrated CPNPs encapsulating a variety of organic fluorophores were successfully synthesized. Well-dispersed CPNPs encapsulating Cy3 amidite exhibited nearly a 5-fold increase in fluorescence quantum yield when compared to the free dye in PBS. FCS diffusion data and cell staining were used to show pH-dependent dissolution of the particles and cellular uptake, respectively. Furthermore, an experimental hydrophobic cell growth inhibitor, ceramide, was successfully delivered in vitro to human vascular smooth muscle cells via encapsulation in CPNPs. These studies demonstrate that CPNPs are effective carriers of dyes and drugs for bioimaging and, potentially, for therapeutic intervention.
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Affiliation(s)
- Thomas T. Morgan
- Material Science and Engineering Department, The Pennsylvania State University, 249 Materials Research Laboratories, Hastings Road, University Park, Pennsylvania 16802
| | - Hari S. Muddana
- Department of Bioengineering, The Pennsylvania State University, 205 Hallowell Building, University Park, Pennsylvania 16802
| | - Erhan I. Altinoǧlu
- Material Science and Engineering Department, The Pennsylvania State University, 249 Materials Research Laboratories, Hastings Road, University Park, Pennsylvania 16802
| | - Sarah M. Rouse
- Material Science and Engineering Department, The Pennsylvania State University, 249 Materials Research Laboratories, Hastings Road, University Park, Pennsylvania 16802
| | - Amra Tabaković
- Material Science and Engineering Department, The Pennsylvania State University, 249 Materials Research Laboratories, Hastings Road, University Park, Pennsylvania 16802
| | - Tristan Tabouillot
- Department of Bioengineering, The Pennsylvania State University, 205 Hallowell Building, University Park, Pennsylvania 16802
| | - Timothy J. Russin
- Departments of Physics and Materials Science and Engineering, The Pennsylvania State University, 104 Davey Laboratory, University Park, Pennsylvania 16802
| | - Sriram S. Shanmugavelandy
- Department of Pharmacology, Penn State Milton S. Hershey Medical Center,. Hershey, Pennsylvania 17033
| | - Peter J. Butler
- Department of Bioengineering, The Pennsylvania State University, 205 Hallowell Building, University Park, Pennsylvania 16802
| | - Peter C. Eklund
- Departments of Physics and Materials Science and Engineering, The Pennsylvania State University, 104 Davey Laboratory, University Park, Pennsylvania 16802
| | - Jong K. Yun
- Department of Pharmacology, Penn State Milton S. Hershey Medical Center,. Hershey, Pennsylvania 17033
| | - Mark Kester
- Department of Pharmacology, Penn State Milton S. Hershey Medical Center,. Hershey, Pennsylvania 17033
| | - James H. Adair
- Material Science and Engineering Department, The Pennsylvania State University, 249 Materials Research Laboratories, Hastings Road, University Park, Pennsylvania 16802
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McKenzie DJ, Garofalo E, Winter MJ, Ceradini S, Verweij F, Day N, Hayes R, van der Oost R, Butler PJ, Chipman JK, Taylor EW. Complex physiological traits as biomarkers of the sub-lethal toxicological effects of pollutant exposure in fishes. Philos Trans R Soc Lond B Biol Sci 2008; 362:2043-59. [PMID: 17475615 PMCID: PMC2442853 DOI: 10.1098/rstb.2007.2100] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Complex physiological traits, such as routine aerobic metabolic rate or exercise performance, are indicators of the functional integrity of fish that can reveal sub-lethal toxicological effects of aquatic pollutants. These traits have proved valuable in laboratory investigations of the sub-lethal effects of heavy metals, ammonia and various xenobiotics. It is not known, however, whether they can also function as biomarkers of the complex potential range of effects upon overall functional integrity caused by exposure to mixtures of chemicals in polluted natural environments. The current study used portable swimming respirometers to compare exercise performance and respiratory metabolism of fish exposed in cages for three weeks to either clean or polluted sites on three urban European river systems: the river Lambro, Milan, Italy; the rivers Blythe, Cole and Tame, Birmingham, UK; and the river Amstel, Amsterdam, The Netherlands. The UK and Italian rivers were variously polluted with high levels of both bioavailable heavy metals and organics, and the Amstel by mixtures of bioavailable organics at high concentrations. In both the UK and Italy, indigenous chub (Leuciscus cephalus) exposed to clean or polluted sites swam equally well in an initial performance test, but the chub from polluted sites could not repeat this performance after a brief recovery interval. These animals were unable to raise the metabolic rate and allocate oxygen towards exercise in the second trial, an effect confirmed in successive campaigns in Italy. Swimming performance was therefore a biomarker indicator of pollutant exposure in chub exposed at these sites. Exposure to polluted sites on the river Amstel did not affect the repeat swimming performance of cultured cloned carp (Cyprinus carpio), indicating either a species-specific tolerance or relative absence of heavy metals. However, measurements of oxygen uptake during swimming revealed increased rates of routine aerobic metabolism in both chub and carp at polluted sites in all of the rivers studied, indicating a sub-lethal metabolic loading effect. Therefore, the physiological traits of exercise performance and metabolic rate have potential as biomarkers of the overall sub-lethal toxic effects of exposure to complex mixtures of pollutants in rivers, and may also provide insight into why fish do not colonize some polluted environments.
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Affiliation(s)
- D J McKenzie
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
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Halsey LG, Handrich Y, Rey B, Fahlman A, Woakes AJ, Butler PJ. Recovery from swimming-induced hypothermia in king penguins: effects of nutritional condition. Physiol Biochem Zool 2008; 81:434-41. [PMID: 18505379 DOI: 10.1086/589546] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
We investigated changes in the rate of oxygen consumption (V O2) and body temperature of wild king penguins (Aptenodytes patagonicus) in different nutritional conditions during recovery after exposure to cold water. Over time, birds undertook an identical experiment three times, each characterized by different nutritional conditions: (1) having recently completed a foraging trip, (2) after fasting for many days, and (3) having been refed one meal after the fast. The experiments consisted of a 2-h session in a water channel followed by a period of recovery in a respirometer chamber on land. Refed birds recovered significantly more quickly than fed birds, in terms of both time to reach resting V O2 on land and time to reach recovery of lower abdominal temperature. Previous work found that when penguins are in cold water, abdominal temperatures decrease less in refed birds than in fed or fasted birds, suggesting that refed birds may be vasoconstricting the periphery while perfusing the gut region to access nutrients. This, alongside an increased resting [V O2], seems the most reasonable explanation for why refed birds recovered more quickly subsequent to cold-water exposure in this study; that is, vasoconstriction of the insulative periphery meant that they lost less heat generated by the body core.
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Affiliation(s)
- L G Halsey
- Centre for Ornithology, School of Biosciences, University of Birmingham, Edgbaston B15 2TT, United Kingdom.
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Abstract
We performed a 40 ns simulation of 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiI-C18(3)) in a 1,2-dipalmitoyl-sn-glycero-3-phosphatidyl choline (DPPC) bilayer in order to facilitate interpretation of lipid dynamics and membrane structure from fluorescence lifetime, anisotropy, and fluorescence correlations spectroscopy (FCS). Incorporation of DiI of 1.6 to 3.2 mol% induced negligible changes in area per lipid but detectable increases in bilayer thickness, each of which are indicators of membrane structural perturbation. The DiI chromophore angle was 77 +/- 17 degrees with respect to the bilayer normal, consistent with rotational diffusion inferred from polarization studies. The DiI headgroup was located 0.63 nm below the lipid head group-water interface, a novel result in contrast to some popular cartoon representations of DiI but consistent with DiI's increase in quantum yield when incorporated into lipid bilayers. Importantly, the fast component of rotational anisotropy matched published experimental results demonstrating that sufficient free volume exists at the sub-interfacial region to support fast rotations. Simulations with non-charged DiI head groups exhibited DiI flip-flop, demonstrating that the positively-charged chromophore stabilizes the orientation and location of DiI in a single monolayer. DiI induced detectable changes in interfacial properties of water ordering, electrostatic potential, and changes in P-N vector orientation of DPPC lipids. The diffusion coefficient of DiI (9.7 +/- 0.02 x 10(-8) cm2 s(-1)) was similar to the diffusion of DPPC molecules (10.7 +/- 0.04 x 10(-8) cm2 s(-1)), supporting the conclusion that DiI dynamics reflect lipid dynamics. These results provide the first atomistic level insight into DiI dynamics, results essential in elucidating lipid dynamics through single molecule fluorescence studies.
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Affiliation(s)
- Ramachandra R Gullapalli
- Department of Bioengineering, The Pennsylvania State University, 228 Hallowell Building, University Park, PA 16802, USA
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Butler PJ, Dong C, Snyder AJ, Jones AD, Sheets ED. Bioengineering and Bioinformatics Summer Institutes: meeting modern challenges in undergraduate summer research. CBE Life Sci Educ 2008; 7:45-53. [PMID: 18316807 PMCID: PMC2262124 DOI: 10.1187/cbe.07-08-0064] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Summer undergraduate research programs in science and engineering facilitate research progress for faculty and provide a close-ended research experience for students, which can prepare them for careers in industry, medicine, and academia. However, ensuring these outcomes is a challenge when the students arrive ill-prepared for substantive research or if projects are ill-defined or impractical for a typical 10-wk summer. We describe how the new Bioengineering and Bioinformatics Summer Institutes (BBSI), developed in response to a call for proposals by the National Institutes of Health (NIH) and the National Science Foundation (NSF), provide an impetus for the enhancement of traditional undergraduate research experiences with intense didactic training in particular skills and technologies. Such didactic components provide highly focused and qualified students for summer research with the goal of ensuring increased student satisfaction with research and mentor satisfaction with student productivity. As an example, we focus on our experiences with the Penn State Biomaterials and Bionanotechnology Summer Institute (PSU-BBSI), which trains undergraduates in core technologies in surface characterization, computational modeling, cell biology, and fabrication to prepare them for student-centered research projects in the role of materials in guiding cell biology.
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Affiliation(s)
- Peter J Butler
- Department of Bioengineering, Penn State College of Medicine, Hershey, PA 17033, USA.
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Abstract
Vascular endothelial cells (ECs) respond to temporal and spatial characteristics of hemodynamic forces by alterations in their adhesiveness to leukocytes, secretion of vasodilators, and permeability to blood-borne constituents. These physiological and pathophysiological changes are tied to adaptation of cell mechanics and mechanotransduction, the process by which cells convert forces to intracellular biochemical signals. The exact time scales of these mechanical adaptations, however, remain unknown. We used particle-tracking microrheology to study adaptive changes in intracellular mechanics in response to a step change in fluid shear stress, which simulates both rapid temporal and steady features of hemodynamic forces. Results indicate that ECs become significantly more compliant as early as 30 s after a step change in shear stress from 0 to 10 dyn/cm(2) followed by recovery of viscoelastic parameters within 4 min of shearing, even though shear stress was maintained. After ECs were sheared for 5 min, return of shear stress to 0 dyn/cm(2) in a stepwise manner did not result in any further rheological adaptation. Average vesicle displacements were used to determine time-dependent cell deformation and macrorheological parameters by fitting creep function to a linear viscoelastic liquid model. Characteristic time and magnitude for shear-induced deformation were 3 s and 50 nm, respectively. We conclude that ECs rapidly adapt their mechanical properties in response to shear stress, and we provide the first macrorheological parameters for time-dependent deformations of ECs to a physiological forcing function. Such studies provide insight into pathologies such as atherosclerosis, which may find their origins in EC mechanics.
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Affiliation(s)
- Jhanvi H Dangaria
- Department of Bioengineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
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