Biophysical journal最新文献

{"title":"Measurement force, speed and post-mortem time affect the ratio of CNS grey to white matter elasticity.","authors":"Julia Monika Becker, Alexander Kevin Winkel, Eva Kreysing, Kristian Franze","doi":"10.1016/j.bpj.2025.03.009","DOIUrl":"https://doi.org/10.1016/j.bpj.2025.03.009","url":null,"abstract":"<p><p>For several decades, many attempts have been made to characterise the mechanical properties of grey and white matter, which constitute the two main compartments of the central nervous system (CNS), with various methods and contradictory results. In particular, the ratio of grey-to-white-matter elasticity is sometimes larger than 1 and sometimes smaller; the reason for this apparent discrepancy is currently unknown. Here, we exploited atomic force microscopy (AFM)-based indentation measurements to systematically investigate how the measurement force, measurement speed, post-mortem interval and temperature affect the measured elasticity of spinal cord tissue, and in particular the ratio of grey-to-white-matter elasticity (K_g/K_w). Within the explored parameter space, increasing measurement force and speed increased the measured elasticity of both grey and white matter. However, K_g/K_w declined from values as high as ∼5 at low forces and speeds to ∼1 for high forces and speeds. K_g/K_w also strongly depended on the anatomical plane in which the measurements were conducted and was considerably higher in transverse sections compared to longitudinal sections. Furthermore, the post-mortem interval impacted both the absolute measured tissue elasticity and K_g/K_w. Grey matter elasticity started decreasing ∼3 hours post-mortem until reaching a plateau after ∼6 hours. In contrast, white matter elasticity started declining from the beginning of the measurements until ∼6 hours post-mortem, when it also levelled off. As a result, K_g/K_w increased until ∼6 hours post-mortem before stabilising. Between 20°C and 38°C, both grey and white matter elasticity decreased at a similar rate, without affecting K_g/K_w. We have thus identified differences in the response of grey and white matter to varying strains and strain rates, and the post-mortem interval, and excluded temperature as a factor affecting K_g/K_w. These differential responses likely contribute to the contradictory results obtained with different methods working in different strain regimes.</p>","PeriodicalId":8922,"journal":{"name":"Biophysical journal","volume":" ","pages":""},"PeriodicalIF":3.2,"publicationDate":"2025-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143647047","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Buckling of red blood cell membrane in narrow capillaries induces excessive wall shear stress.","authors":"Deyun Liu, Kazuyasu Sugiyama, Xiaobo Gong","doi":"10.1016/j.bpj.2025.03.010","DOIUrl":"https://doi.org/10.1016/j.bpj.2025.03.010","url":null,"abstract":"<p><p>The deformation of red blood cells (RBCs) in Poiseuille flows of capillary vessels is fundamental for hemodynamics in cellular scale for various physiological or pathological scenarios. However, the mechanical criterion for membrane buckling and the impact of the asymmetric deformations of cells on the hemodynamics are currently unclear. In this study, a microfluidic system with narrow tubular channels was set up for experimental observations, and numerical simulations using the Immersed Boundary Method were performed to illustrate the deformation of RBCs and their surrounding flow fields in detail. The dependence of the buckling on the capillary number (a dimensionless parameter measuring the ratio of viscous fluid force with elastic force of membrane) was discovered. Then we derived the criterion of buckling of cell membrane under local circumferential pressure by considering the buckling of an elastic ring with neglecting thickness. Results also show that the extra pressure drop and the wall shear stress associated with the appearance of membrane buckling increase non-linearly. This work provides biomechanical fundamentals for mechanobiological studies of microvascular disease associated with the change of mechanical properties of RBCs.</p>","PeriodicalId":8922,"journal":{"name":"Biophysical journal","volume":" ","pages":""},"PeriodicalIF":3.2,"publicationDate":"2025-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143647045","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Structural and Hydrodynamic Characterization of Dimeric Human Oligoadenylate Synthetase 2.","authors":"Amit Koul, Danielle Gemmill, Nikhat Lubna, Markus Meier, Natalie Krahn, Evan P Booy, Jörg Stetefeld, Trushar R Patel, Sean A McKenna","doi":"10.1016/j.bpj.2025.02.025","DOIUrl":"https://doi.org/10.1016/j.bpj.2025.02.025","url":null,"abstract":"","PeriodicalId":8922,"journal":{"name":"Biophysical journal","volume":" ","pages":""},"PeriodicalIF":3.2,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143630169","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Aggregation and disaggregation of red blood cells: depletion versus bridging.","authors":"Nicolas Moreno, Kirill Korneev, Alexey Semenov, Alper Topuz, Thomas John, Minne Paul Lettinga, Marco Ellero, Christian Wagner, Dmitry A Fedosov","doi":"10.1016/j.bpj.2025.03.007","DOIUrl":"https://doi.org/10.1016/j.bpj.2025.03.007","url":null,"abstract":"<p><p>The aggregation of red blood cells (RBCs) is a complex phenomenon that strongly impacts blood flow and tissue perfusion. Despite extensive research for more than 50 years, physical mechanisms that govern RBC aggregation are still under debate. Two proposed mechanisms are based on bridging and depletion interactions between RBCs due to the presence of macromolecules in blood plasma. The bridging hypothesis assumes the formation of bonds between RBCs through adsorbing macromolecules, while the depletion mechanism results from the exclusion of macromolecules from the inter-cellular space, leading to effective attraction. Existing experimental studies generally cannot differentiate between these two aggregation mechanisms, though several recent investigations suggest concurrent involvement of the both mechanisms. We explore dynamic aggregation and disaggregation of two RBCs using three simulation models: a potential-based model mimicking depletion interactions, a bridging model with immobile bonds, and a new bridging model with mobile bonds which can slide along RBC membranes. Simulation results indicate that dynamic aggregation of RBCs primarily arises from depletion interactions, while disaggregation of RBCs involves both mechanisms. The bridging model with mobile bonds reproduces well the corresponding experimental data, offering insights into the interplay between bridging and depletion interactions and providing a framework for studying similar interactions between other biological cells.</p>","PeriodicalId":8922,"journal":{"name":"Biophysical journal","volume":" ","pages":""},"PeriodicalIF":3.2,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143633402","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Control of cardiac waves in human iPSC-CM syncytia by a Halbach array and magnetic nanoparticles.","authors":"Maria R Pozo, Yuli W Heinson, Christianne J Chua, Emilia Entcheva","doi":"10.1016/j.bpj.2025.03.006","DOIUrl":"https://doi.org/10.1016/j.bpj.2025.03.006","url":null,"abstract":"<p><p>The Halbach array, originally developed for particle accelerators, is a compact arrangement of permanent magnets that creates well-defined magnetic fields without heating. Here, we demonstrate its use for modulating the speed of electromechanical waves in cardiac syncytia of human stem cell-derived cardiomyocytes. At 40-50 mT magnetic field strength, a cylindrical dipolar Halbach array boosted the conduction velocity, CV, by up to 25% when the magnetic field was co-aligned with the electromechanical wave (but not when perpendicular to it). To observe the effects, a short-term incubation of the cardiac cell constructs with non-targeted magnetic nanoparticles, mNPs, was sufficient. This led to increased CV anisotropy, and effects were most pronounced at slower pacing rates. Instantaneous formation and re-arrangement of elongated mNP clusters upon magnetic field rotation was seen, creating dynamic structural anisotropy that may have contributed to the directional CV effects. This approach may be useful for anti-arrhythmic control of cardiac waves.</p>","PeriodicalId":8922,"journal":{"name":"Biophysical journal","volume":" ","pages":""},"PeriodicalIF":3.2,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143613324","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"FAIR Data for Optical Tweezers Experiments.","authors":"Matthew T J Halma, Sowmiyaa Kumar, Jan van Eck, Sanne Abeln, Alexander Gates, Gijs J L Wuite","doi":"10.1016/j.bpj.2025.03.005","DOIUrl":"https://doi.org/10.1016/j.bpj.2025.03.005","url":null,"abstract":"<p><p>The single-molecule biophysics community has delivered significant impacts to our understanding of fundamental biological processes, yet the field is also siloed and has fragmented data structures which impede data sharing and limit the ability to conduct comprehensive meta-analyses. To advance the field of optical tweezers in single-molecule biophysics, it is important that the field adopts open and collaborative data sharing that facilitate meta-analyses that combine diverse resources and supports more advanced analyses, akin to those seen in projects like the Protein Data Bank and the 1000 Genomes Project. Here, we assess the state of data findability, accessibility, interoperability, and reusability (the FAIR principles) within the single-molecule optical tweezers field. By combining a qualitative review with quantitative tools from bibliometrics, our analysis suggests that the field has significant room for improvement in terms of FAIR adherence. Finally, we discuss the potential of compulsory data deposition and a minimal set of metadata standards to ensure reproducibility and interoperability between systems. While implementing these measures may not be straightforward, they are key steps that will enhance the integration of optical tweezers biophysics with the broader biomedical literature.</p>","PeriodicalId":8922,"journal":{"name":"Biophysical journal","volume":" ","pages":""},"PeriodicalIF":3.2,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143623369","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Electrotaxis disrupts patterns of cell-cell interactions of human corneal epithelial cells in vitro.","authors":"Rebecca M Crossley, Simon F Martina-Perez","doi":"10.1016/j.bpj.2025.03.004","DOIUrl":"https://doi.org/10.1016/j.bpj.2025.03.004","url":null,"abstract":"<p><p>Electrotaxis, the process by which eukaryotic cells establish a polarity and move directionally along an electric field, is a well-studied mechanism to steer the migration of cells in vitro and in vivo. While the influence of an electric field on single cells in culture is well-documented, the influence of the electric field on cell-cell interactions has not been well studied. In this work, we quantify the length, duration and number of cell-cell interactions during electrotaxis of human corneal epithelial cells and compare the properties of these interactions with those arising in the absence of an electric field. We find that contact inhibition of locomotion and velocity alignment, two key behaviours observed during dynamic physical interactions between cells in vitro, are strongly affected by an electric field. Furthermore, we establish a link between the location of a cell-cell contact on the cell surface and the resulting cell interaction behaviours. By mapping the regions of the cell surface with a characteristic response to contact with another cell, we find that the spatial distribution of possible responses upon cell-cell contact is altered upon induction of an electric field. Altogether, this work shows how the electric field not only influences individual cell motility and directionality, but also affects cell-cell interactions.</p>","PeriodicalId":8922,"journal":{"name":"Biophysical journal","volume":" ","pages":""},"PeriodicalIF":3.2,"publicationDate":"2025-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143613325","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Escherichia coli α-hemolysin induces red blood cell retention in a microfluidic spleen-like device.","authors":"Nicolás Andrés Saffioti, Emilia Belén Sousa, Mickaël Marin, María Florencia Leal Denis, Mariano Aníbal Ostuni, Vanesa Herlax, Pablo Julio Schwarzbaum, Diego Pallarola","doi":"10.1016/j.bpj.2025.03.001","DOIUrl":"https://doi.org/10.1016/j.bpj.2025.03.001","url":null,"abstract":"<p><p>α-hemolysin (HlyA) is a major exotoxin secreted by uropathogenic Escherichia coli (UPEC), known for its ability to lyse red blood cells (RBCs). While its lytic effects are well characterized, the non-lytic alterations on RBCs, such as increased permeability to Ca²⁺, osmotic imbalance, and morphological alterations, remain less understood and may be critical in UPEC pathogenesis. This study investigates the impact of these non-lytic alterations on the rheology and mechanics of RBCs using two biomimetic microfluidic devices that model key aspects of RBCs' circulation. In the first device, which mimics the mechanical deformation of RBCs in narrow capillaries, HlyA sublytic concentrations were found to significantly impair RBC deformability. These changes were accompanied by an increase in cytosolic Ca²⁺ and volume expansion. In contrast, the non-acylated protoxin, ProHlyA, neither impaired the deformability of RBCs nor triggered changes in cytosolic Ca²⁺ or cell volume. The second device, which simulates the RBCs' filtration by the spleen's red pulp, revealed that HlyA, but not ProHlyA, increased RBCs' retention in small gaps resembling splenic fenestrations. The extent of RBCs' retention was partially mitigated by blocking purinergic signaling, indicating a contribution of the HlyA-induced volume increase in this process. Our results suggest that the increase in cytosolic Ca²⁺ elicited by HlyA impacts RBCs' circulation by decreasing RBCs' deformability and increasing spleen retention. However, this impairment of RBCs' performance can function as a defense mechanism to aid in the retention of HlyA-bound RBCs, removing them from circulation, and potentially preventing vascular hemolysis.</p>","PeriodicalId":8922,"journal":{"name":"Biophysical journal","volume":" ","pages":""},"PeriodicalIF":3.2,"publicationDate":"2025-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143613326","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Pair cross-correlation analysis for assessing protein co-localization.","authors":"Pintu Patra, Cecilia Sanchez, Michael Lanzer, Ulrich S Schwarz","doi":"10.1016/j.bpj.2025.03.002","DOIUrl":"https://doi.org/10.1016/j.bpj.2025.03.002","url":null,"abstract":"<p><p>Measuring co-localization of different types of molecules is essential to understand molecular organization in biological systems. The pair cross-correlation (PCC) function computed from two-color microscopy images provides a measure of co-localization between differently labeled molecules. Here, we compute a theoretical expression for the PCC function between two molecules using two-dimensional Gaussian distributions as the effective point spread functions for single molecules. Through our analytical calculations, we provide a quantitative description of PCC in the case of multiple signal pairs. By fitting our analytical solutions to simulated images, we can estimate both small and large separation distances. We then apply this method to malaria-infected red blood cells (RBCs) imaged by stimulated emission depletion (STED) microscopy. We cross-correlate the signal for the knob-associated histidine-rich protein (KAHRP), which the parasite uses to remodel the spectrin-actin network of RBCs, with different signals from the RBCs and find that its average separation from the ankyrin junctions increases from 40 nm to 120 nm during the 48 hours of the infectious cycle.</p>","PeriodicalId":8922,"journal":{"name":"Biophysical journal","volume":" ","pages":""},"PeriodicalIF":3.2,"publicationDate":"2025-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143613327","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Brief Life-Story of Irreversibly Sickled Cells.","authors":"Merav Socolovsky","doi":"10.1016/j.bpj.2025.03.003","DOIUrl":"https://doi.org/10.1016/j.bpj.2025.03.003","url":null,"abstract":"","PeriodicalId":8922,"journal":{"name":"Biophysical journal","volume":" ","pages":""},"PeriodicalIF":3.2,"publicationDate":"2025-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143603881","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}