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Mebrahtu A, Smith IC, Liu S, Abusara Z, Leonard TR, Joumaa V, Herzog W. Reconsidering assumptions in the analysis of muscle fibre cross-sectional area. J Exp Biol 2024; 227:jeb248187. [PMID: 39319442 DOI: 10.1242/jeb.248187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2024] [Accepted: 09/09/2024] [Indexed: 09/26/2024]
Abstract
Cross-sectional area (CSA) is a fundamental variable in characterizing muscle mechanical properties. Typically, the CSA of a single muscle fibre is assessed by measuring either one or two diameters, and assuming the cross-section is either circular or elliptical in shape. However, fibre cross-sections have irregular shapes. The accuracy and precision of CSAs determined using circular and elliptical shape assumptions are unclear for mammalian skinned muscle fibres. Second harmonic generation imaging of skinned rabbit soleus fibres revealed that the circular assumption overstated real CSA by 5.3±25.9% whereas the elliptical assumption overstated real CSA by 2.8±6.9%. A preferred rotational alignment can bias the circular assumption, as real CSA was overstated by 22.1±24.8% when using the larger fibre diameter and understated by 11.4±13% when using the smaller fibre diameter. With 73% lower variable error and reduced bias, the elliptical assumption is superior to the circular assumption when assessing the CSA of skinned mammalian fibres.
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Affiliation(s)
- Abel Mebrahtu
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, 2500 University Drive NW, Calgary, AB, Canada, T2N 1N4
| | - Ian C Smith
- Ottawa Hospital Research Institute, 1053 Carling Ave, Ottawa, ON, Canada, K1Y 4E9
| | - Shuyue Liu
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, 2500 University Drive NW, Calgary, AB, Canada, T2N 1N4
| | - Ziad Abusara
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, 2500 University Drive NW, Calgary, AB, Canada, T2N 1N4
| | - Timothy R Leonard
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, 2500 University Drive NW, Calgary, AB, Canada, T2N 1N4
| | - Venus Joumaa
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, 2500 University Drive NW, Calgary, AB, Canada, T2N 1N4
| | - Walter Herzog
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, 2500 University Drive NW, Calgary, AB, Canada, T2N 1N4
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2
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Tomalka A, Weidner S, Hahn D, Seiberl W, Siebert T. Force re-development after shortening reveals a role for titin in stretch-shortening performance enhancement in skinned muscle fibres. J Exp Biol 2024; 227:jeb247377. [PMID: 39119673 DOI: 10.1242/jeb.247377] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Accepted: 08/02/2024] [Indexed: 08/10/2024]
Abstract
Stretch-shortening cycles (SSCs) involve muscle lengthening (eccentric contractions) instantly followed by shortening (concentric contractions). This combination enhances force, work and power output compared with pure shortening contractions, which is known as the SSC effect. Recent evidence indicates both cross-bridge (XB)-based and non-XB-based (e.g. titin) structures contribute to this effect. This study analysed force re-development following SSCs and pure shortening contractions to gain further insight into the roles of XB and non-XB structures regarding the SSC effect. Experiments were conducted on rat soleus muscle fibres (n=16) with different SSC velocities (30%, 60% and 85% of maximum shortening velocity) and constant stretch-shortening magnitudes (18% of optimum length). The XB inhibitor blebbistatin was used to distinguish between XB and non-XB contributions to force generation. The results showed SSCs led to significantly greater [mean±s.d. 1.02±0.15 versus 0.68±0.09 (ΔF/Δt); t62=8.61, P<0.001, d=2.79) and faster (75 ms versus 205 ms; t62=-6.37, P<0.001, d=-1.48) force re-development compared with pure shortening contractions in the control treatment. In the blebbistatin treatment, SSCs still resulted in greater [0.11±0.03 versus 0.06±0.01 (ΔF/Δt); t62=8.00, P<0.001, d=2.24) and faster (3010±1631 versus 7916±3230 ms; t62=-8.00, P<0.001, d=-1.92) force re-development compared with pure shortening contractions. These findings deepen our understanding of the SSC effect, underscoring the involvement of non-XB structures such as titin in modulating force production. This modulation is likely to involve complex mechanosensory coupling from stretch to signal transmission during muscle contraction.
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Affiliation(s)
- André Tomalka
- Motion and Exercise Science, University of Stuttgart, 70569 Stuttgart, Germany
| | - Sven Weidner
- Motion and Exercise Science, University of Stuttgart, 70569 Stuttgart, Germany
| | - Daniel Hahn
- Human Movement Science, Faculty of Sports Science, Ruhr University Bochum, 44801 Bochum, Germany
- School of Human Movement and Nutrition Sciences, University of Queensland, Brisbane, QLD 4067, Australia
| | - Wolfgang Seiberl
- Human Movement Science, University of the Bundeswehr Munich, 85579 Neubiberg, Germany
| | - Tobias Siebert
- Motion and Exercise Science, University of Stuttgart, 70569 Stuttgart, Germany
- Stuttgart Center for Simulation Science, University of Stuttgart, 70569 Stuttgart, Germany
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3
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Nakada M, Kanda J, Uchiyama H, Matsumura K. Nanoscale intracellular ultrastructures affected by osmotic pressure using small-angle X-ray scattering. Biophys Chem 2024; 312:107287. [PMID: 38981174 DOI: 10.1016/j.bpc.2024.107287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2024] [Revised: 06/12/2024] [Accepted: 06/26/2024] [Indexed: 07/11/2024]
Abstract
Although intracellular ultrastructures have typically been studied using microscopic techniques, it is difficult to observe ultrastructures at the submicron scale of living cells due to spatial resolution (fluorescence microscopy) or high vacuum environment (electron microscopy). We investigate the nanometer scale intracellular ultrastructures of living CHO cells in various osmolality using small-angle X-ray scattering (SAXS), and especially the structures of ribosomes, DNA double helix, and plasma membranes in-cell environment are observed. Ribosomes expand and contract in response to osmotic pressure, and the inter-ribosomal correlation occurs under isotonic and hyperosmolality. The DNA double helix is not dependent on the osmotic pressure. Under high osmotic pressure, the plasma membrane folds into form a multilamellar structure with a periodic length of about 6 nm. We also study the ultrastructural changes caused by formaldehyde fixation, freezing and heating.
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Affiliation(s)
- Masaru Nakada
- Toray Research Center, Inc., 2-11 Sonoyama 3-chome, Otsu, Shiga 520-8567, Japan.
| | - Junko Kanda
- Toray Research Center, Inc., 2-11 Sonoyama 3-chome, Otsu, Shiga 520-8567, Japan
| | - Hironobu Uchiyama
- Toray Research Center, Inc., 2-11 Sonoyama 3-chome, Otsu, Shiga 520-8567, Japan
| | - Kazuaki Matsumura
- School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi, Ishikawa 923-1292, Japan
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Han SW, Boldt K, Joumaa V, Herzog W. Characterizing residual and passive force enhancements in cardiac myofibrils. Biophys J 2023; 122:1538-1547. [PMID: 36932677 PMCID: PMC10147830 DOI: 10.1016/j.bpj.2023.03.022] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2022] [Revised: 11/07/2022] [Accepted: 03/14/2023] [Indexed: 03/19/2023] Open
Abstract
Residual force enhancement (RFE), an increase in isometric force after active stretching of a muscle compared with the purely isometric force at the corresponding length, has been consistently observed throughout the structural hierarchy of skeletal muscle. Similar to RFE, passive force enhancement (PFE) is also observable in skeletal muscle and is defined as an increase in passive force when a muscle is deactivated after it has been actively stretched compared with the passive force following deactivation of a purely isometric contraction. These history-dependent properties have been investigated abundantly in skeletal muscle, but their presence in cardiac muscle remains unresolved and controversial. The purpose of this study was to investigate whether RFE and PFE exist in cardiac myofibrils and whether the magnitudes of RFE and PFE increase with increasing stretch magnitudes. Cardiac myofibrils were prepared from the left ventricles of New Zealand White rabbits, and the history-dependent properties were tested at three different final average sarcomere lengths (n = 8 for each), 1.8, 2, and 2.2 μm, while the stretch magnitude was kept at 0.2 μm/sarcomere. The same experiment was repeated with a final average sarcomere length of 2.2 μm and a stretching magnitude of 0.4 μm/sarcomere (n = 8). All 32 cardiac myofibrils exhibited increased forces after active stretching compared with the corresponding purely isometric reference conditions (p < 0.05). Furthermore, the magnitude of RFE was greater when myofibrils were stretched by 0.4 compared with 0.2 μm/sarcomere (p < 0.05). We conclude that, like in skeletal muscle, RFE and PFE are properties of cardiac myofibrils and are dependent on stretch magnitude.
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Affiliation(s)
- Seong-Won Han
- Institute of Physiology II, Faculty of Medicine, University of Münster, Münster, Germany; Faculty of Kinesiology, University of Calgary, Calgary, Canada.
| | - Kevin Boldt
- Faculty of Kinesiology, University of Calgary, Calgary, Canada; Kinesiology Program, Trent University, Peterborough, ON, Canada; Department of Human Health and Nutritional Science, University of Guelph, Guelph, ON, Canada
| | - Venus Joumaa
- Faculty of Kinesiology, University of Calgary, Calgary, Canada
| | - Walter Herzog
- Faculty of Kinesiology, University of Calgary, Calgary, Canada
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Hahn D, Han SW, Joumaa V. The history-dependent features of muscle force production: A challenge to the cross-bridge theory and their functional implications. J Biomech 2023; 152:111579. [PMID: 37054597 DOI: 10.1016/j.jbiomech.2023.111579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2023] [Accepted: 04/03/2023] [Indexed: 04/15/2023]
Abstract
The cross-bridge theory predicts that muscle force is determined by muscle length and the velocity of active muscle length changes. However, before the formulation of the cross-bridge theory, it had been observed that the isometric force at a given muscle length is enhanced or depressed depending on active muscle length changes before that given length is reached. These enhanced and depressed force states are termed residual force enhancement (rFE) and residual force depression (rFD), respectively, and together they are known as the history-dependent features of muscle force production. In this review, we introduce early attempts in explaining rFE and rFD before we discuss more recent research from the past 25 years which has contributed to a better understanding of the mechanisms underpinning rFE and rFD. Specifically, we discuss the increasing number of findings on rFE and rFD which challenge the cross-bridge theory and propose that the elastic element titin plays a role in explaining muscle history-dependence. Accordingly, new three-filament models of force production including titin seem to provide better insight into the mechanism of muscle contraction. Complementary to the mechanisms behind muscle history-dependence, we also show various implications for muscle history-dependence on in-vivo human muscle function such as during stretch-shortening cycles. We conclude that titin function needs to be better understood if a new three-filament muscle model which includes titin, is to be established. From an applied perspective, it remains to be elucidated how muscle history-dependence affects locomotion and motor control, and whether history-dependent features can be changed by training.
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Affiliation(s)
- Daniel Hahn
- Human Movement Science, Faculty of Sport Science, Ruhr University, Bochum, Germany; School of Human Movement and Nutrition Sciences, University of Queensland, Australia
| | - Seong-Won Han
- Institute of Physiology II, Faculty of Medicine, University of Münster, Germany.
| | - Venus Joumaa
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Alberta, Canada
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Contento VS, Power GA. Eccentric exercise-induced muscle weakness amplifies the history dependence of force. Eur J Appl Physiol 2023; 123:749-767. [PMID: 36447012 DOI: 10.1007/s00421-022-05105-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Accepted: 11/16/2022] [Indexed: 12/05/2022]
Abstract
INTRODUCTION Following active lengthening or shortening contractions, isometric steady-state torque is increased (residual force enhancement; rFE) or decreased (residual force depression; rFD), respectively, compared to fixed-end isometric contractions at the same muscle length and level of activation. Though the mechanisms underlying this history dependence of force have been investigated extensively, little is known about the influence of exercise-induced muscle weakness on rFE and rFD. PURPOSE Assess rFE and rFD in the dorsiflexors at 20%, 60%, and 100% maximal voluntary torque (MVC) and activation matching, and electrically stimulated at 20% MVC, prior to, 1 h following, and 24 h following 150 maximal eccentric dorsiflexion contractions. METHODS Twenty-six participants (13 male, 24.7 ± 2.0y; 13 female, 22.5 ± 3.6y) were seated in a dynamometer with their right hip and knee angle set to 110° and 140°, respectively, with an ankle excursion set between 0° and 40° plantar flexion (PF). MVC torque, peak twitch torque, and prolonged low frequency force depression were used to assess eccentric exercise-induced neuromuscular impairments. History-dependent contractions consisted of a 1 s isometric (40°PF or 0°PF) phase, a 1 s shortening or lengthening phase (40°/s), and an 8 s isometric (0°PF or 40°PF) phase. RESULTS Following eccentric exercise; MVC torque was decreased, prolonged low frequency force depression was present, and both rFE and rFD increased for all maximal and submaximal conditions. CONCLUSIONS The history dependence of force during voluntary torque and activation matching, and electrically stimulated contractions is amplified following eccentric exercise. It appears that a weakened neuromuscular system amplifies the magnitude of the history-dependence of force.
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Affiliation(s)
- Vincenzo S Contento
- Department of Human Health and Nutritional Sciences, College of Biological Science, University of Guelph, Guelph, ON, N1G 2W1, Canada
| | - Geoffrey A Power
- Department of Human Health and Nutritional Sciences, College of Biological Science, University of Guelph, Guelph, ON, N1G 2W1, Canada.
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Hessel AL, Kuehn M, Palmer BM, Nissen D, Mishra D, Joumaa V, Freundt J, Ma W, Nishikawa KC, Irving T, Linke WA. The distinctive mechanical and structural signatures of residual force enhancement in myofibers. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.19.529125. [PMID: 36865266 PMCID: PMC9980001 DOI: 10.1101/2023.02.19.529125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
In muscle, titin proteins connect myofilaments together and are thought to be critical for contraction, especially during residual force enhancement (RFE) when force is elevated after an active stretch. We investigated titin's function during contraction using small-angle X-ray diffraction to track structural changes before and after 50% titin cleavage and in the RFE-deficient, mdm titin mutant. We report that the RFE state is structurally distinct from pure isometric contractions, with increased thick filament strain and decreased lattice spacing, most likely caused by elevated titin-based forces. Furthermore, no RFE structural state was detected in mdm muscle. We posit that decreased lattice spacing, increased thick filament stiffness, and increased non-crossbridge forces are the major contributors to RFE. We conclude that titin directly contributes to RFE.
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Affiliation(s)
- Anthony L. Hessel
- Institute of Physiology II, University of Muenster; Muenster, Germany
| | - Michel Kuehn
- Institute of Physiology II, University of Muenster; Muenster, Germany
| | - Bradley M. Palmer
- Department of Molecular Physiology and Biophysics, University of Vermont; Burlington, VT, 05405-1705, USA
| | - Devin Nissen
- BioCAT, Department of Biology, Illinois Institute of Technology; Chicago, IL, USA
| | - Dhruv Mishra
- Department of Biological Sciences, University of Northern Arizona; Flagstaff AZ, USA
| | - Venus Joumaa
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, AB T2N1N4, Canada
| | - Johanna Freundt
- Institute of Physiology II, University of Muenster; Muenster, Germany
| | - Weikang Ma
- BioCAT, Department of Biology, Illinois Institute of Technology; Chicago, IL, USA
| | - Kiisa C. Nishikawa
- Department of Biological Sciences, University of Northern Arizona; Flagstaff AZ, USA
| | - Thomas Irving
- BioCAT, Department of Biology, Illinois Institute of Technology; Chicago, IL, USA
| | - Wolfgang A. Linke
- Institute of Physiology II, University of Muenster; Muenster, Germany
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Effects of shortening velocity on the stiffness to force ratio during isometric force redevelopment suggest mechanisms of residual force depression. Sci Rep 2023; 13:948. [PMID: 36653512 PMCID: PMC9849346 DOI: 10.1038/s41598-023-28236-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Accepted: 01/16/2023] [Indexed: 01/19/2023] Open
Abstract
Although the phenomenon of residual force depression has been known for decades, the mechanisms remain elusive. In the present study, we investigated mechanisms of residual force depression by measuring the stiffness to force ratio during force redevelopment after shortening at different velocities. The results showed that the slope of the relationship between muscle stiffness and force decreased with decreasing shortening velocity, and the y-intercept increased with decreasing shortening velocity. The differing slopes and y-intercepts indicate that the stiffness to force ratio during isometric force redevelopment depends on the active shortening velocity at a given muscle length and activation level. The greater stiffness to force ratio after active shortening can potentially be explained by weakly-bound cross bridges in the new overlap zone. However, weakly-bound cross bridges are insufficient to explain the reduced slope at the slowest shortening velocity because the reduced velocity should increase the proportion of weakly- to strongly-bound cross bridges, thereby increasing the slope. In addition, if actin distortion caused by active shortening recovers during the force redevelopment period, then the resulting slope should be similar to the non-linear slope of force redevelopment over time. Alternatively, we suggest that a tunable elastic element, such as titin, could potentially explain the results.
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Liu S, Joumaa V, Herzog W. Fast stretching of skeletal muscle fibres abolishes residual force enhancement. J Exp Biol 2022; 225:275232. [PMID: 35485194 DOI: 10.1242/jeb.244011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Accepted: 04/26/2022] [Indexed: 11/20/2022]
Abstract
The steady-state isometric force of a muscle after active stretching is greater than the steady-state force for a purely isometric contraction at the same length and activation level. The mechanisms underlying this property, termed residual force enhancement (rFE), remain unknown. When myofibrils are actively stretched while cross-bridge cycling is inhibited, rFE is substantially reduced, suggesting that cross-bridge cycling is essential to produce rFE. Our purpose was to further investigate the role of cross-bridge cycling in rFE by investigating whether fast stretching that causes cross-bridge slipping is associated with a loss of rFE. Skinned fibre bundles from rabbit psoas muscles were stretched slowly (0.08 µm s-1) or rapidly (800 µm s-1) while activated, from an average sarcomere length of 2.4 to 3.2 µm. Force was enhanced by 38%±4% (mean±s.e.m) after the slow stretches but was not enhanced after the fast stretches, suggesting that proper cross-bridge cycling is required to produce rFE.
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Affiliation(s)
- Shuyue Liu
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
| | - Venus Joumaa
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
| | - Walter Herzog
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
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Ma W, Irving TC. Small Angle X-ray Diffraction as a Tool for Structural Characterization of Muscle Disease. Int J Mol Sci 2022; 23:3052. [PMID: 35328477 PMCID: PMC8949570 DOI: 10.3390/ijms23063052] [Citation(s) in RCA: 32] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 03/01/2022] [Accepted: 03/02/2022] [Indexed: 02/01/2023] Open
Abstract
Small angle X-ray fiber diffraction is the method of choice for obtaining molecular level structural information from striated muscle fibers under hydrated physiological conditions. For many decades this technique had been used primarily for investigating basic biophysical questions regarding muscle contraction and regulation and its use confined to a relatively small group of expert practitioners. Over the last 20 years, however, X-ray diffraction has emerged as an important tool for investigating the structural consequences of cardiac and skeletal myopathies. In this review we show how simple and straightforward measurements, accessible to non-experts, can be used to extract biophysical parameters that can help explain and characterize the physiology and pathology of a given experimental system. We provide a comprehensive guide to the range of the kinds of measurements that can be made and illustrate how they have been used to provide insights into the structural basis of pathology in a comprehensive review of the literature. We also show how these kinds of measurements can inform current controversies and indicate some future directions.
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Affiliation(s)
- Weikang Ma
- The Biophysics Collaborative Access Team (BioCAT), Center for Synchrotron Radiation Research and Instrumentation (CSSRI), Illinois Institute of Technology, Chicago, IL 60616, USA;
- Department of Biology, Illinois Institute of Technology, Chicago, IL 60616, USA
| | - Thomas C. Irving
- The Biophysics Collaborative Access Team (BioCAT), Center for Synchrotron Radiation Research and Instrumentation (CSSRI), Illinois Institute of Technology, Chicago, IL 60616, USA;
- Department of Biology, Illinois Institute of Technology, Chicago, IL 60616, USA
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