European Biophysics Journal最新文献

Multicellular structures, including cell sheets, are actively used as model systems to study intercellular interactions and can be applied in different areas of regenerative medicine. In this paper, we present a novel approach for measuring mechanical properties of cell sheets based on a simple experimental setup and numerical simulations. The advantage of the present approach is the relative ease of the sample preparation, while previous systems for the tensile tests required specialized and sensitive equipment. With the developed approach, the cell sheet on a polymer membrane is mounted in the holder on one side, and then deflection of the free end of the membrane is measured. The deflection of this cantilever-like construction depends on the elastic modulus of the membrane (which is known) and cell sheet, and also from the traction force generated by the cell sheet. By involving an experimental step with relaxing the traction force and by conducting finite element simulations, both traction force and elastic properties of the cell sheet can be estimated. We performed such measurements on cell sheets from keratocytes from corneal explants and confirmed that the developed approach is applicable for measurement of both traction force and elastic modulus of cell sheets.

Biophysics is an interdisciplinary science that applies the theories and methods of physics to understand biological systems. It encompasses a wide range of topics, from the molecular mechanisms within cells to the physical properties of organisms and ecosystems. The goal of biophysics is to uncover the physical principles underlying the structure and function of biological molecules, cells, and cellular systems, providing a deeper understanding of life itself. The Institute of Biophysics, Czech Academy of Sciences (IBP) stands as a beacon of excellence in the field of biophysical research in the Czech Republic. This article delves into its history, structure, research areas, and major scientific achievements, highlighting the role of IBP in the global scientific community.

The 26th International Analytical Ultracentrifugation Workshop and Symposium (AUC2024) took place at the scenic Banz Abbey near Bad Staffelstein, Germany, from July 22 to 27, 2024. 84 participants from 16 countries (Belgium 1, Canada 7, China 3, Colombia 1, Czech Republic 3, Finland 1, France 3, Germany 35, Israel 1, Italy 1, Japan 2, New Zealand 2, Spain 1, Switzerland 4, United Kingdom 5, United States 14) travelled to Germany to present and discuss the latest advances in the field. 40 workshop sessions were held by world-leading experts covering all aspects of AUC including experimental design, data analysis and data processing according to good manufacturing practice (GMP), but also complementary methods such as hydrodynamic modelling, isothermal titration calorimetry and small angle X-ray scattering data processing were considered. A visit to a stalactite cave in Franconian Switzerland and the Bavarian beer museum in Kulmbach offered a welcome change to the scientific program and started off the 3-day symposium. The presentations featured of course AUC, but also dynamic and static light scattering, small angle X-ray and neutron scattering, surface plasmon resonance, field flow fractionation, calorimetry, chromatography, and electron microscopy. The AUC2024 special volume provides a comprehensive overview of the sustained innovation, utility and relevance of AUC and related solution biophysical and particle technology methods across various disciplines, including biochemistry, structural biology, synthetic polymer chemistry, carbohydrate chemistry, protein and nucleic acid characterization, nano and colloids science, and macromolecular interactions.

The development of snake venom-based therapeutics and antivenoms is closely linked to understanding how snake venoms modulate the physicochemical properties of biological membranes. In this study, we investigated the effects of Macrovipera lebetina venom on the surface electrical characteristics of rat liver mitochondrial membranes in vitro. A combination of electrokinetic and mechanical techniques was employed, including measurements of mitochondrial electrophoretic mobility and the bending elasticity of phosphatidylcholine membrane models. Exposure to Macrovipera lebetina venom significantly increased the net surface charge of mitochondria, while adenosine triphosphatase (ATPase) activity remained unchanged. Morphological alterations and vesicle aggregation, observed via light scattering and fluorescence microscopy, indicated reduced binding of α-D-mannosyl and α-D-glucosyl residues to the outer mitochondrial membrane in the presence of venom. In addition, malondialdehyde assays revealed elevated levels of oxidized lipid species in venom-treated mitochondria. A pronounced softening of model phosphatidylcholine membranes was also observed, likely associated with lipid oxidation induced by the venom. It states that the effect of the venom of the Macrovipera lebetina on the surface electrical charge of rat liver mitochondria is being studied in vitro. The surface charge is a physicochemical characteristic of the mitochondrial membrane.

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Rubisco activase (Rca) is critical for maintaining Rubisco activity during photosynthesis by removing inhibitory sugar phosphates through ATP hydrolysis. Despite its importance, the structural and functional diversity of Rca across species remain poorly understood. This study compares the oligomeric assembly, thermal stability, and functional activities of α- and β-isoforms of Rca from cotton, creosote, Antarctic hairgrass, and Sitka spruce, representing diverse thermal and ecological adaptations. We found that cotton and creosote Rca isoforms form highly polydisperse complexes in solution, with no evidence of discrete hexamer formation, even in the presence of Mg.ATPγS. In contrast, Antarctic hairgrass α-Rca and Sitka spruce β-Rca formed stable hexamers under similar conditions. Spruce α-Rca exhibited unique redox-dependent oligomerization, forming large complexes stabilized by disulfide bonds. Thermal stability assays revealed significant nucleotide-induced stabilization in most isoforms, with hexamer formation enhancing stability and activity in select cases. Functional assays showed that hexamer-forming isoforms displayed superior Rubisco reactivation and ATP hydrolysis activities, even at low protein concentrations, while smaller oligomeric assemblies also supported activity in some species. These findings provide new insights into the structural and functional adaptations of Rca, highlighting the role of oligomeric assembly and environmental influences on its activity. This work lays a foundation for improving photosynthetic efficiency by targeting Rca isoforms tailored to specific environmental conditions.

The theory, computational modelling and data analysis of hydrodynamic and other solution properties of macromolecules and nanoparticles in dilute solution are nowadays well-established. Along this essay, we briefly present the variety of methods which are currently available for those purposes. Although such methods embody an important complexity, they are usually presented as user-friendly tools which can be used without previous knowledge of their foundations. Some understanding of classical concepts in which modern tools are based can result in a better, more profitable, use of them and a most adequate form of presenting and discussing their results. We describe the utility of employing a systematic way of handling data and results for the solution properties in terms of equivalent radii, which indeed provide an alternative to the raw properties in their use for structural determinations. They can also be employed in the design of simulation of experiments and data analysis procedures, like in analytical ultracentrifugation as we propose finally in this paper.

Efficient molecular transport via reversible electroporation requires sustained existence of the pore without causing irreversible cellular damage. In this study, we used molecular dynamics simulations to investigate pore formation during electroporation, and we characterized the transition to hydrophilic pores. Our simulations reveal that during the hydrophilic state, the reapplication of an electric field, even at reduced magnitudes, extends the pore duration while maintaining structural integrity. Furthermore, we established that the pore size can be controlled by regulating the intervals between successive electric field pulses, offering precise control over membrane permeabilization. These findings provide a foundation for fine-tuning electroporation protocols, enabling customized permeabilization strategies based on the properties of the molecules to be delivered. This approach has the potential to significantly improve the efficacy of targeted drug delivery and gene therapy. It also creates new possibilities for precise and controlled cellular manipulation in therapeutic contexts.