Xarxes complexes en biologia cel·lular

A les cèl·lules, una mul�� tud de biomolècules canvien i interaccionen dinàmicament formant un entramat extraordinàriament complex que lliga metabolisme, proteoma i genoma entre si i amb l'entorn. Entendre com el conjunt de funcionalitats i comportaments cel·lulars emergeixen de tota aquesta complexitat d'interaccions en constant canvi i evolució és un dels grans reptes per al coneixement en el segle ������. La ciència de les xarxes complexes ens permet abordar l'estudi de la biologia cel·lular a gran escala més enllà dels cons�� tuents individuals. Des d'aquest enfocament, en aquest ar�� cle repassarem breument alguns dels resultats més recents en la inves�� gació dels sistemes cel·lulars, incloent-hi la redundància i plas�� citat del metabolisme, mètodes capaços de detectar errors en la determinació experimental d'interaccions entre proteïnes, i l'explicació de fenòmens evolu�� us en termes del mapa geno�� p-feno�� p

Xarxes complexes en biologia cel·lular

A les cèl·lules, una mul�� tud de biomolècules canvien i interaccionen dinàmicament formant un entramat extraordinàriament complex que lliga metabolisme, proteoma i genoma entre si i amb l'entorn. Entendre com el conjunt de funcionalitats i comportaments cel·lulars emergeixen de tota aquesta complexitat d'interaccions en constant canvi i evolució és un dels grans reptes per al coneixement en el segle ������. La ciència de les xarxes complexes ens permet abordar l'estudi de la biologia cel·lular a gran escala més enllà dels cons�� tuents individuals. Des d'aquest enfocament, en aquest ar�� cle repassarem breument alguns dels resultats més recents en la inves�� gació dels sistemes cel·lulars, incloent-hi la redundància i plas�� citat del metabolisme, mètodes capaços de detectar errors en la determinació experimental d'interaccions entre proteïnes, i l'explicació de fenòmens evolu�� us en termes del mapa geno�� p-feno�� p

Scaling approach to order-parameter fluctuations in disordered frustrated systems

We present a constructive approach to obtain information about the compactness and shape of large-scale lowest excitations in disordered systems by studying order-parameter fluctuations (OPF) at low temperatures. We show that the parameter $G$ which measures OPF is 1/3 at T=0 provided the ground state is unique and the probability distribution for the lowest excitations is gapless and with finite weight at zero-excitation energy. We then apply zero-temperature scaling to describe the energy and volume spectra of the lowest large-scale excitations which scale with the system size and have a weight at ze ro energy $\hat{P}_v(0)\sim l^{-\theta'}$ with $v=l^d$. A low-temperature expansion reveals that, OPF vanish like $L^{-\theta}$, if $\theta> 0$ and remain finite for space filling lowest excitations with $\theta=0$. The method can be extended to extract information about the shape and fractal surface of the large-scale lowest excitations.Comment: 4 pages, REVTeX. Some modifications; final version accepted for publication in J. Phys. A: Math. and General (Letters

Paper-based platform with an in situ molecularly imprinted polymer for ß-amyloid

Alzheimers disease (AD) is one of the most common forms of dementia affecting millions of people worldwide. Currently, an easy and effective form of diagnosis is missing, which significantly hinders a possible improvement of the patients quality of life. In this context, biosensors emerge as a future solution, opening the doors for preventive medicine and allowing the premature diagnosis of numerous pathologies. This work presents a pioneering biosensor that combines a bottom-up design approach using paper as a platform for the electrochemical recognition of peptide amyloid -42 (A-42), a biomarker for AD present in blood, associated with visible differences in the brain tissue and responsible for the formation of senile plaques. The sensor layer relies on a molecularly imprinted polymer as a biorecognition element, created on the carbon ink electrodes surface by electropolymerizing a mixture of the target analyte (A-42) and a monomer (O-phenylenediamine) at neutral pH 7.2. Next, the template molecule was removed from the polymeric network by enzymatic and acidic treatments. The vacant sites so obtained preserved the shape of the imprinted protein and were able to rebind the target analyte. Morphological and chemical analyses were performed in order to control the surface modification of the materials. The analytical performance of the biosensor was evaluated by an electroanalytical technique, namely, square wave voltammetry. For this purpose, the analytical response of the biosensor was tested with standard solutions ranging from 0.1 ng/mL to 1 g/mL of A-42. The linear response of the biosensor went down to 0.1 ng/mL. Overall, the developed biosensor offered numerous benefits, such as simplicity, low cost, reproducibility, fast response, and repeatability less than 10%. All together, these features may have a strong impact in the early detection of AD.The authors acknowledge funding from project PTDC/AAGTEC/5400/2014, POCI-01-0145-FEDER-016637, POCI-01-0145-FEDER-007688, and UID/CTM/50025/2019 funded by European funds through FEDER (European Funding or Regional Development) via COMPETE2020 - POCI (operational program for internationalization and competitively) by national funding through the National Foundation for Science and Technology, I.P. (FCT-MCTES). Additionally, they are grateful to the project IBEROS, Instituto de Bioingenieria en Red para el Envejecimiento Saludable, POCTEP/0245-BEROS-1-E, PROGRAMA INTERREG 2014-2020 funded through FEDER within the cooperation region of Galiza/Spain and North of Portugal. A.C.M. and F.T.C.M. gratefully acknowledges FCT-MCTES for the financial support (PhD grant reference SFRH/BD/115173/2016 intituled “Nanobiosensing platform based on MIP-SERS for breast cancer exosome characterization and detection” and Post-Doc grant reference SFRH/BPD/97891/2013 intituled “Biomedical devices for easier and quicker screening procedures of the Alzheimer’s). This work is part of the Master Thesis in Micro and Nanotechnology Engineering defended by Marta V. Pereira. at FCT NOVA titled “Fabrication of 3D electrodes for biosensor applications” in December 2018.info:eu-repo/semantics/publishedVersio

A conjectured scenario for order-parameter fluctuations in spin glasses

We study order-parameter fluctuations (OPF) in disordered systems by considering the behavior of some recently introduced paramaters $G,G_c$ which have proven very useful to locate phase transitions. We prove that both parameters G (for disconnected overlap disorder averages) and $G_c$ (for connected disorder averages) take the respective universal values 1/3 and 13/31 in the $T\to 0$ limit for any {\em finite} volume provided the ground state is {\em unique} and there is no gap in the ground state local-field distributions, conditions which are met in generic spin-glass models with continuous couplings and no gap at zero coupling. This makes $G,G_c$ ideal parameters to locate phase transitions in disordered systems much alike the Binder cumulant is for ordered systems. We check our results by exactly computing OPF in a simple example of uncoupled spins in the presence of random fields and the one-dimensional Ising spin glass. At finite temperatures, we discuss in which conditions the value 1/3 for G may be recovered by conjecturing different scenarios depending on whether OPF are finite or vanish in the infinite-volume limit. In particular, we discuss replica equivalence and its natural consequence $\lim_{V\to\infty}G(V,T)=1/3$ when OPF are finite. As an example of a model where OPF vanish and replica equivalence does not give information about G we study the Sherrington-Kirkpatrick spherical spin-glass model by doing numerical simulations for small sizes. Again we find results compatible with G=1/3 in the spin-glass phase.Comment: 18 pages, 9 postscript figure

The pearl oyster Pinctada imbricata radiata (Leach, 1814) (Bivalvia: Pteriidae) reaches Minorca, Balearic Islands

En prens

Temperature shifts in the Sinai model: static and dynamical effects

We study analytically and numerically the role of temperature shifts in the simplest model where the energy landscape is explicitely hierarchical, namely the Sinai model. This model has both attractive features (there are valleys within valleys in a strict self similar sense), but also one important drawback: there is no phase transition so that the model is, in the large size limit, effectively at zero temperature. We compute various static chaos indicators, that are found to be trivial in the large size limit, but exhibit interesting features for finite sizes. Correspondingly, for finite times, some interesting rejuvenation effects, related to the self similar nature of the potential, are observed. Still, the separation of time scales/length scales with temperatures in this model is much weaker that in experimental spin-glasses.Comment: 19 pages, Revtex4, eps figure

Fragility of the Free-Energy Landscape of a Directed Polymer in Random Media

We examine the sensitiveness of the free-energy landscape of a directed polymer in random media with respect to various kinds of infinitesimally weak perturbation including the intriguing case of temperature-chaos. To this end, we combine the replica Bethe ansatz approach outlined in cond-mat/0112384, the mapping to a modified Sinai model and numerically exact calculations by the transfer-matrix method. Our results imply that for all the perturbations under study there is a slow crossover from a weakly perturbed regime where rare events take place to a strongly perturbed regime at larger length scales beyond the so called overlap length where typical events take place leading to chaos, i.e. a complete reshuffling of the free-energy landscape. Within the replica space, the evidence for chaos is found in the factorization of the replicated partition function induced by infinitesimal perturbations. This is the reflex of explicit replica symmetry breaking.Comment: 29 pages, Revtex4, ps figure

Harmonization of experimental procedures to assess mitochondrial respiration in human permeabilized skeletal muscle fibers

Aim: High-resolution respirometry in human permeabilized muscle fibers is extensively used for analysis of mitochondrial adaptions to nutrition and exercise interventions, and is linked to athletic performance. However, the lack of standardization of experimental conditions limits quantitative inter- and intra-laboratory comparisons. Methods: In our study, an international team of investigators measured mitochondrial respiration of permeabilized muscle fibers obtained from three biopsies (vastus lateralis) from the same healthy volunteer to avoid inter-individual variability. High-resolution respirometry assays were performed together at the same laboratory to assess whether the heterogenity in published results are due to the effects of respiration media (MiR05 versus Z) with or without the myosin inhibitor blebbistatin at low- and high-oxygen regimes. Results: Our findings reveal significant differences between respiration media for OXPHOS and ETcapacities supported by NADH&succinate-linked substrates at different oxygen concentrations. Respiratory capacities were approximately 1.5-fold higher in MiR05 at high-oxygen regimes compared to medium Z near air saturation. The presence or absence of blebbistatin in human permeabilized muscle fiber preparations was without effect on oxygen flux. Conclusion: Our study constitutes a basis to harmonize and establish optimum experimental conditions for respirometric studies of permeabilized human skeletal muscle fibers to improve reproducibility

Establim contacte: guia plàstica de contacte amb tacte

Control oficial; MCA; Plàstics; AlimentsControl oficial; MCA; Plásticos; AlimentosOfficial control; MCA; Plastics; FoodL’objectiu d’aquesta publicació és facilitar les tasques de control oficial que duen a terme els tècnics de l’ASPCAT en les inspeccions a les empreses que fabriquen i/o importen materials i objectes en contacte amb aliments de naturalesa plàstica. Per aquest motiu, hem elaborat un procediment i una guia d’inspecció que intenta sistematitzar i establir una priorització dels aspectes a avaluar en les unitats de control. El procediment inclou la sistemàtica a seguir per a la realització de les unitats de control i en la guia s’especifiquen els diferents aspectes a revisar. Per a cada un dels ítems a valorar s’inclou una introducció normativa, s’especifiquen els aspectes que s’haurien d’avaluar en la visita d’inspecció i es concreta com efectuar-ne la revisió. Hem volgut aprofundir en l’avaluació de la conformitat dels MCA: l’assignació de simulants, les condicions d’assaig, la verificació dels resultats dels assajos de migració i en definitiva, la conformitat dels MCA. Considerem que és un aspecte cabdal verificar la conformitat i alhora també una tasca complexa. Per aquest motiu, els hi dediquem una atenció especial.El objetivo de esta publicación es facilitar las labores de control oficial que realizan los técnicos de ASPCAT y ASPB en las inspecciones de empresas que fabrican y/o importan materiales plásticos y objetos en contacto con alimentos. Por ello, hemos elaborado un procedimiento y una guía de inspección que trata de sistematizar y establecer una priorización de los aspectos a evaluar en las unidades de control oficial. El procedimiento incluye la sistemática a seguir para la realización de las unidades de control y la guía especifica los diferentes aspectos a revisar. Para cada uno de los elementos a evaluar, se incluye una introducción normativa, se especifican los aspectos que deben evaluarse durante la visita de inspección y se define cómo llevar a cabo la revisión. Queríamos profundizar en la evaluación de la conformidad de los MCA: la asignación de simulantes, las condiciones de ensayo y la verificación de los resultados de los ensayos de migración, en definitiva, la conformidad de los MCA. Consideramos que es un aspecto clave para verificar la conformidad y al mismo tiempo también es una tarea compleja. Por ello, les prestamos especial atención.The aim of this publication is to facilitate the official control tasks carried out by ASPCAT and ASPB technicians in the inspections of companies that manufacture and/or import plastic materials and objects in contact with food. For this reason, we have drawn up a procedure and an inspection guide that tries to systematize and establish a prioritization of the aspects to be evaluated in the control units. The procedure includes the system to follow for the realization of the control units and the guide specifies the different aspects to be reviewed. For each of the items to be assessed, a normative introduction is included, the aspects that should be assessed during the inspection visit are specified and it is defined how to carry out the review. We wanted to deepen the assessment of the conformity of the MCAs: the assignment of simulants, the test conditions, and the verification of the results of the migration tests, in short, the conformity of the MCAs. We consider that it is a key aspect to verify conformity and, at the same time, it is a complex task. For this reason, we pay special attention to them