Showing papers in "Biophysical Journal in 2012"

TL;DR: It is demonstrated that membrane disruption by Aβ occurs by a two-step process, with the initial formation of ion-selective pores followed by nonspecific fragmentation of the lipid membrane during amyloid fiber formation.

TL;DR: Increased negative surface charge correlates strongly with increased protein solubility and may be due to strong binding of water by the acidic amino acids, and the results obtained for the two different precipitants agree closely with each other, suggesting that the two precipitant probe similar properties that are relevant to solubilty in buffer alone.

TL;DR: The results provide compelling evidence in support of weak intermolecular interactions, in contrast to the notion that the electroviscous effect is important in governing the viscoelastic behavior of concentrated mAb solutions.

TL;DR: This work successfully simulate the dynamics of the electronic energy transfer of the Fenna-Matthews-Olson pigment-protein complex and presents one of the first steps to explain the role of excitonic quantum coherence in photosynthetic light-harvesting complexes based on their atomistic and molecular description.

TL;DR: Findings reveal a differential adaptation of cytoskeletal dynamics to substrate stiffness in growth cones of different neuronal types, and highlight the potential importance of the mechanical properties of the cellular environment for neuronal navigation during embryonic development and nerve regeneration.

TL;DR: Overall, the data indicate that fibrillar α-syn and HttEx1, rather than their precursor oligomers, are highly cytotoxic, the toxicity being associated to their ability to bind and permeabilize the cell membranes.

TL;DR: The ability of T cells to quantitatively respond to substrate rigidly provides an intriguing new model for mechanobiology.

TL;DR: It is concluded that under extension and/or compression an α-helix to β-sheet conversion of the coiled-coils occurs in the fibrin clot as a part of forced protein unfolding.

TL;DR: An atomic-level description of the binding process suggests opportunities for allosteric modulation and provides a structural foundation for future optimization of binding and unbinding rates.

TL;DR: A highly accurate method to determine Gaussian curvature modulus κ¯ in computer simulations relies on the interplay between curvature stress and edge tension of partially curved axisymmetric membrane disks and requires determining their closing probability.

TL;DR: Cell-culture platforms of nanotemplated "nanostraws" that pierce the cell membrane, providing a permanent fluidic pipeline into the cell for direct cytosolic access, open the way for active, reproducible delivery of a wide variety of species into cells without endocytosis.

TL;DR: This work finds that both the spread area and the substrate stiffness influence traction forces in an independent manner, but these factors have opposite effects: cells on stiffer substrates produce higher average forces, whereas cells with larger spread areas generate lower average forces.

TL;DR: This work applied fluorescence fluctuation spectroscopy to quantitatively characterize and enhance the MS2 system and used a single-chain tandem dimer of MCP that significantly increased the uniformity and sensitivity of mRNA labeling and concluded that the PP7 system performs better for RNA labeling.

TL;DR: High-resolution topographic and quantitative mechanics data of phase-separated SLBs are acquired using a recent atomic force microscopy (AFM) imaging mode based on force measurements to evaluate the contribution of the underlying hard support in the determination of the elastic properties of SLBs and to determine the adequate indentation range for obtaining reliable elastic moduli values.

TL;DR: DeconSTORM approximates the maximum likelihood sample estimate under a realistic statistical model of fluorescence microscopy movies comprising numerous frames and enables an approximately fivefold or greater increase in imaging speed by allowing a higher density of activated fluorophores/frame.

TL;DR: It is proposed that DHA may be the more bioactive component of fish oil that serves to disrupt lipid raft domain organization, and represents an evolution in the view of how PUFA remodel membrane architecture.

TL;DR: This work extracts Raman spectral signatures by means of information measures to identify cell components such as the nucleus, the endoplasmic reticulum, the Golgi apparatus, and mitochondria and generates representations equivalent to conventional (immuno)fluorescence images with more than three cell components at a time.

TL;DR: This work suggests that mechanical activation of cells is accompanied by distinct timescales involved in the reorganization of actin and chromatin assembly, followed by translocation of transcription cofactors from the cytoplasm to the nucleus.

TL;DR: It is deduced that individual bacteria entering a flow system can rapidly migrate upstream much faster than a gradually advancing biofilm.

TL;DR: This work shows that naïve ES cells decondense their chromatin in the course of downregulating the pluripotency marker Nanog before they initiate lineage commitment, and links this biophysical phenotype to coinciding epigenetic differences, including histone methylation, and shows a strong correlation of chromatin condensation and nuclear stiffness with the expression of Nanog.

TL;DR: This work presents the first, to their knowledge, atomistically detailed picture of CR binding to protofibrils of the Alzheimer Aβ(9-40) peptide, and shows that birefringence upon CR binding is due to the anisotropic orientation of the CR dipoles resulting from the spatial ordering of these molecules in the grooves along the fibril axis.

TL;DR: The results demonstrate that the presence of a sizeable parasite greatly reduces the ability of RBCs to deform under stretching, and the observed loss of deformability can be predicted quantitatively using the local membrane elasticity measured by micropipettes.

TL;DR: It is shown that despite the polarization sensitivity of the ChC Raman spectrum, cholesterol monohydrate crystals can be reliably discriminated from aliphatic lipids, from structural proteins of the tissue matrix and from other condensed structures, including cholesteryl esters.

TL;DR: A systematic statistical analysis of the recently measured individual trajectories of fluorescently labeled telomeres in the nucleus of living human cells establishes a rigorous mathematical characterization of the stochastic process and identifies the basic mathematical mechanisms behind the telomere motion.

TL;DR: A dimerization interface is proposed between α-helices 4 and 5 and the loop between β2 and β3 and seems to explain why the residues D47, E49, R135, R161, and R164 of this interface are influencing Ras signaling in cellular physiological experiments, although they are not positioned in the catalytic site.

TL;DR: This work presents a systematic Bayesian approach to multiple-hypothesis testing of a general set of competing motion models based on particle mean-square displacements that automatically classifies particle motion, properly accounting for sampling limitations and correlated noise while appropriately penalizing model complexity according to Occam's Razor to avoid over-fitting.

TL;DR: A fast, high-throughput method for characterizing the motility of microorganisms in three dimensions based on standard imaging microscopy by analyzing the spatiotemporal fluctuations of the intensity in the sample from time-lapse images and obtaining the intermediate scattering function of the system.

TL;DR: It is hypothesize surfactants disrupt the membrane locally due to a spontaneous segregation from the lipid and/or packing defects and refer to them as heterogeneously perturbing and this may account for enhanced activity, selectivity, and mutual synergism of antimicrobial biosurfactants and reduced destabilization of membrane proteins by CHAPS or digitonin.

TL;DR: The electrostatic forces of the ion cloud surrounding βLg play a key role in the thermodynamics and kinetics of dimer association/dissociation, and a mechanism for dimer stabilization whereby the added ionic species screen and neutralize charges in the vicinity of the dimer interface is proposed.

TL;DR: In this article, the authors combine atomic force microscopy-based force spectroscopy with fluorescence microscopy to produce high-resolution elasticity maps for three different types of live neuronal cells: cortical (embryonic rat), embryonic chick dorsal root ganglion, and P-19 (mouse embryonic carcinoma stem cells) neurons.