Multiphoton absorption in amyloid protein fibres

Fibrillization of peptides leads to the formation of amyloid fibres, which, when in large aggregates, are responsible for diseases such as Alzheimer's and Parkinson's. Here, we show that amyloids have strong nonlinear optical absorption, which is not present in native non-fibrillized protein. Z-scan and pump-probe experiments indicate that insulin and lysozyme β-amyloids, as well as α-synuclein fibres, exhibit either two-photon, three-photon or higher multiphoton absorption processes, depending on the wavelength of light. We propose that the enhanced multiphoton absorption is due to a cooperative mechanism involving through-space dipolar coupling between excited states of aromatic amino acids densely packed in the fibrous structures. This finding will provide the opportunity to develop nonlinear optical techniques to detect and study amyloid structures and also suggests that new protein-based materials with sizable multiphoton absorption could be designed for specific applications in nanotechnology, photonics and optoelectronics

Search for supersymmetric particles in scenarios with a gravitino LSP and stau NLSP

Sleptons, neutralinos and charginos were searched for in the context of scenarios where the lightest supersymmetric particle is the gravitino. It was assumed that the stau is the next-to-lightest supersymmetric particle. Data collected with the DELPHI detector at a centre-of-mass energy near 189 GeV were analysed combining the methods developed in previous searches at lower energies. No evidence for the production of these supersymmetric particles was found. Hence, limits were derived at 95% confidence level.Comment: 31 pages, 14 figure

Computational and Statistical Analyses of Amino Acid Usage and Physico-Chemical Properties of the Twelve Late Embryogenesis Abundant Protein Classes

Late Embryogenesis Abundant Proteins (LEAPs) are ubiquitous proteins expected to play major roles in desiccation tolerance. Little is known about their structure - function relationships because of the scarcity of 3-D structures for LEAPs. The previous building of LEAPdb, a database dedicated to LEAPs from plants and other organisms, led to the classification of 710 LEAPs into 12 non-overlapping classes with distinct properties. Using this resource, numerous physico-chemical properties of LEAPs and amino acid usage by LEAPs have been computed and statistically analyzed, revealing distinctive features for each class. This unprecedented analysis allowed a rigorous characterization of the 12 LEAP classes, which differed also in multiple structural and physico-chemical features. Although most LEAPs can be predicted as intrinsically disordered proteins, the analysis indicates that LEAP class 7 (PF03168) and probably LEAP class 11 (PF04927) are natively folded proteins. This study thus provides a detailed description of the structural properties of this protein family opening the path toward further LEAP structure - function analysis. Finally, since each LEAP class can be clearly characterized by a unique set of physico-chemical properties, this will allow development of software to predict proteins as LEAPs

Search for neutral heavy leptons produced in ZZ decays

Weak isosinglet Neutral Heavy Leptons (νm) have been searched for using data collected by the DELPHI detector corresponding to 3.3 × 106 hadronic Z0 decays at LEP1. Four separate searches have been performed, for short-lived νm production giving monojet or acollinear jet topologies, and for long-lived νm giving detectable secondary vertices or calorimeter clusters. No indication of the existence of these particles has been found, leading to an upper limit for the branching ratio BR(Z0 → νmν̄) of about 1.3 × 10-6 at 95% confidence level for νm masses between 3.5 and 50 GeV/c2. Outside this range the limit weakens rapidly with the νm mass. The results are also interpreted in terms of limits for the single production of excited neutrinos. © Springer-Verlag 1997

Measurements of top-quark pair differential cross-sections in the lepton plus jets channel in pp collisions at root s=8 TeV using the ATLAS detector

Measurements of normalized differential cross-sections of top-quark pair production are presented as a function of the top-quark, tt¯tt¯ system and event-level kinematic observables in proton–proton collisions at a centre-of-mass energy of s√=8TeVs=8TeV . The observables have been chosen to emphasize the tt¯tt¯ production process and to be sensitive to effects of initial- and final-state radiation, to the different parton distribution functions, and to non-resonant processes and higher-order corrections. The dataset corresponds to an integrated luminosity of 20.3 fb −1−1 , recorded in 2012 with the ATLAS detector at the CERN Large Hadron Collider. Events are selected in the lepton+jets channel, requiring exactly one charged lepton and at least four jets with at least two of the jets tagged as originating from a b-quark. The measured spectra are corrected for detector effects and are compared to several Monte Carlo simulations. The results are in fair agreement with the predictions over a wide kinematic range. Nevertheless, most generators predict a harder top-quark transverse momentum distribution at high values than what is observed in the data. Predictions beyond NLO accuracy improve the agreement with data at high top-quark transverse momenta. Using the current settings and parton distribution functions, the rapidity distributions are not well modelled by any generator under consideration. However, the level of agreement is improved when more recent sets of parton distribution functions are used

The mRNA cap-binding protein eIF4E in post-transcriptional gene expression

Eukaryotic initiation factor 4E (eIF4E) has central roles in the control of several aspects of post-transcriptional gene expression and thereby affects developmental processes. It is also implicated in human diseases. This review explores the relationship between structural, biochemical and biophysical aspects of eIF4E and its function in vivo, including both long-established roles in translation and newly emerging ones in nuclear export and mRNA decay pathways