A5030982200- Cardiomyopathy and Myosin Studies
- Muscle Physiology and Disorders
- Cardiovascular Effects of Exercise
- Muscle activation and electromyography studies
- Force Microscopy Techniques and Applications
- Cellular Mechanics and Interactions
- DNA and Nucleic Acid Chemistry
- Advanced Sensor and Energy Harvesting Materials
- Cardiovascular Function and Risk Factors
- thermodynamics and calorimetric analyses
- Sports injuries and prevention
- Advanced MRI Techniques and Applications
- Nanopore and Nanochannel Transport Studies
- Mechanical and Optical Resonators
- Advanced Fluorescence Microscopy Techniques
- Bacteriophages and microbial interactions
- Orbital Angular Momentum in Optics
- Sports Performance and Training
- Neurobiology and Insect Physiology Research
- Particle Accelerators and Free-Electron Lasers
- Molecular Junctions and Nanostructures
- Body Composition Measurement Techniques
- Genetic Neurodegenerative Diseases
- Neurogenetic and Muscular Disorders Research
- Lubricants and Their Additives
University of Florence
2016-2025
Sapienza University of Rome
2006-2009
National Interuniversity Consortium for the Physical Sciences of Matter
2007-2009
Istituto Nazionale per la Fisica della Materia
2003-2007
Northwestern University
2005
University of Pavia
2005
European Synchrotron Radiation Facility
2000
European Molecular Biology Laboratory
2000
Istituto Tumori Bari
1994
Ospedale Generale Regionale Francesco Miulli
1982
1. Steady lengthenings at different velocities (0.025‐1.2 microns/s per half‐sarcomere; temperature 2‐5.5 degrees C) were imposed on isolated frog muscle fibres the isometric tetanus plateau by means of a loudspeaker motor. The lengthening sarcomere level was measured striation follower either in fixed‐end or length‐clamp mode. force response capacitance gauge transducer (resonance frequency 50 kHz). Preparations showing gross non‐homogeneity during excluded. 2. A steady tension all cases...
During skeletal muscle contraction, regular arrays of actin and myosin filaments slide past each other driven by the cyclic ATP-dependent interaction motor protein II (the cross-bridge) with actin. The rate cross-bridge cycle its load-dependence, defining shortening velocity energy consumption at molecular level, vary widely among different isoforms II. However, underlying mechanisms remain poorly understood. We have addressed this question applying a single-molecule approach to rapidly...
Significance This paper represents a major advance in understanding intrinsic heart beat regulation, because it provides an integrated view of the Frank–Starling law that combines mechanical, structural, and energetic aspects performance. We show mechanosensing myosin filament adjusts number motors recruited from off, ATP hydrolysis-unavailable state to systolic force. In this way, cost is tuned end pressure–volume relation. These results elucidate plausible mechanistic link between...
In maximally Ca2+-activated demembranated fibres from the mammalian skeletal muscle, depression of force by lowering temperature below physiological level (~35 °C) is explained reduction in myosin motor. Instead, cooling reported to not affect per motor cardiac trabeculae rat ventricle. Here, mechanism performance reinvestigated with fast sarcomere-level mechanics. We determine changes half-sarcomere compliance range temperatures 10-30 °C and analyse data terms a simplified mechanical model...
Understanding of complex biological processes requires knowledge molecular structures and measurement their dynamics in vivo. The collective chemomechanical action myosin molecules (the motors) the muscle sarcomere represents a paradigmatic example this respect. Here, we describe label-free imaging method sensitive to protein conformation We employed order-based contrast enhancement by second-harmonic generation (SHG) for functional cells. found that SHG polarization anisotropy (SPA)...
A shortening muscle is a machine that converts metabolic energy into mechanical work, but, when stretched, it acts as brake, generating high resistive force at low cost. The braking action of can be activated with remarkable speed, the leg extensor muscles rapidly decelerate body end jump. Here we used time-resolved x-ray and measurements on isolated cells to elucidate molecular basis its rapid control. We show stretch only 5 nm between each overlapping set myosin actin filaments in...
Myosin motors in the thick filament of resting striated (skeletal and cardiac) muscle are trapped an OFF state, which packed helical tracks on surface, inhibiting their interactions with actin utilization ATP. To investigate structural changes induced mammalian skeletal by temperature, we collected x-ray diffraction patterns from fast extensor digitorum longus mouse temperature range near physiological (35°C) to 10°C, maximal isometric force (T0) shows a threefold decrease. In muscle,...
Titin is a molecular spring in parallel with myosin motors each muscle half-sarcomere, responsible for passive force development at sarcomere length (SL) above the physiological range (>2.7 μm). The role of titin SL unclear and investigated here single intact cells frog ( Rana esculenta ), by combining half-sarcomere mechanics synchrotron X-ray diffraction presence 20 μM para-nitro-blebbistatin, which abolishes activity maintains them resting state even during activation cell electrical...
Myosin II is the motor protein that produces force and shortening in muscle by ATP-driven cyclic interactions of its globular portion, head, with actin filament. During each interaction myosin head undergoes a conformational change, working stroke, which, depending on mechanical conditions, can generate several piconewtons or an axial displacement filament toward centre sarcomere nanometres. However, sizes elementary length steps their dependence conditions are still under question. Due to...
Axial x-ray diffraction patterns from single intact fibers of frog skeletal muscle were recorded by using a highly collimated beam at the European Synchrotron Radiation Facility. During isometric contraction sarcomere lengths 2.2–3.2 μm, M3 reflection, associated with repeat myosin heads along filaments, was resolved into two peaks. The total intensity decreased linearly increasing length and directly proportional to degree overlap between actin showing that it comes in region. separation...
1. Steady lengthenings at different velocities (0.02‐1.6 microns/s per half‐sarcomere, temperature 2.5‐5.5 degrees C) were imposed on isolated frog muscle fibres the plateau of isometric tetanus (tension T0). When tension during lengthening had attained a steady value (Ti), which varied from about 1.5 to 2 times T0 depending velocity, transients elicited by applying step length changes amplitudes. The change in selected segment, close end fibre connected force transducer, was controlled...
1. The force-velocity (P-V) relation for normal or NO-3 treated single fibres isolated from the semitendinosus muscle of frog was determined at given times during rise tension and plateau isometric tetani. Experiments were made about 2.25 micron sarcomere length constant temperatures, 3 to 4.5 degrees C 19 21 C. controlled-velocity release method used. 2. During tension, any initial higher than 0.2 P0, lowest velocity required drop zero same as tetanic plateau, independent temperature...
Muscle contraction is due to myosin motors that transiently attach with their globular head an actin filament and generate force. After a sudden reduction of the load below maximum isometric force (T0), attached heads execute axial movement (the working stroke) drives sliding toward center sarcomere by amount larger at lower 11 nm near zero load. Here, we show increase in temperature from 2 17 degrees C, which increases average per 60%, does not affect promoted T0 0.7T0, whereas it reduces...
A conventional five-step chemo-mechanical cycle of the myosin–actin ATPase reaction, which implies myosin detachment from actin upon release hydrolysis products (ADP and phosphate, Pi) binding a new ATP molecule, is able to fit [Pi] dependence force number motors during isometric contraction skeletal muscle. However, this scheme not explain why rate fast muscle decreased by an increase in much less than motors. The question can be solved assuming presence branch cycle: contraction, when...