Hygroscopy of Single-Stranded DNA Nano-Brushes: Atomic Workings of its Hydration-Induced Deformation

Hydration control of structure and mechanical properties is a process widely exploited in living organisms for key biological functions and, most recently, also in man-made smart materials. Here, the challenge of unveiling the underlying atomistic mechanisms of this phenomenon using all-atom Molecular Dynamics (MD) simulations to model the hygroscopic properties of polymer-brushes composed by single-stranded DNA (ssDNA) molecules is faced. The simulations identify three swelling regimes with a markedly different mechanical response. This evolution is produced by the competition between the formation of additional water–ssDNA and water–water hydrogen bonds, in a subtle interplay with the co-evolving structure of the ssDNA SAM. This cooperative interaction between conformational and hydration degrees of freedom should be applicable to other polymer brushes and related hydrogen-bonded systems. The results have direct implications for the use of ssDNA SAMs as sequencing devices, explaining the crucial role of the polymer-brush density in the SAM collective response to hydration, and for the alternative design of hygroscopic materials, that exploit the extreme hygroscopic power of biological polymers like ssDNA brusheThe authors thank the Spanish MINECO for financial support (project MAT2017-83273-R). J.G.V and R.P. acknowledge support from the Spanish Ministry of Science and Innovation, through project PID2020- 115864RB-I00 and the “María de Maeztu” Programme for Units of Excellence in R&D (CEX2018-000805-M). J.G.V. acknowledge support from the Spanish Ministry of Science and Innovation (PID2020- 113722RJ-I00) and Spanish CM “Talento Program” Project No. 2020-T1/ ND-2030

Practical guide to single-protein AFM nanomechanical spectroscopy mapping: insights and pitfalls as unraveled by all-atom MD simulations on immunoglobulin G

Atomic force microscopy is an invaluable characterization tool in almost every biophysics laboratory. However, obtaining atomic/sub-nanometer resolution on single proteins has thus far remained elusive - a feat long achieved on hard substrates. In this regard, nanomechanical spectroscopy mapping may provide a viable approach to overcome this limitation. By complementing topography with mechanical properties measured locally, one may thus enhance spatial resolution at the single-protein level. In this work, we perform all-atom molecular dynamics simulations of the indentation process on a single immunoglobulin G (IgG) adsorbed on a graphene slab. Our simulations reveal three different stages as a function of strain: a noncontact regime - where the mechanical response is linked to the presence of the water environment - followed by an elastic response and a final plastic deformation regime. In the noncontact regime, we are able to identify hydrophobic/hydrophilic patches over the protein. This regime provides the most local mechanical information that allows one to discern different regions with similar height/topography and leads to the best spatial resolution. In the elastic regime, we conclude that the Young modulus is a well-defined property only within mechanically decoupled domains. This is caused by the fact that the elastic deformation is associated with a global reorganization of the domain. Differences in the mechanical response are large enough to clearly resolve domains within a single protein, such as the three subunits forming the IgG. Two events, unfolding or protein slipping, are observed in the plastic regime. Our simulations allow us to characterize these two processes and to provide a strategy to identify them in the force curves. Finally, we elaborate on possible challenges that could hamper the interpretation of such experiments/simulations and how to overcome them. All in all, our simulations provide a detailed picture of nanomechanical spectroscopy mapping on single proteins, showing its potential and the challenges that need to be overcome to unlock its full potentialJ.G.V. acknowledges funding from a Marie Sklodowska-Curie Fellowship within the Horizon 2020 framework (Grant No. DLV-795286) and the Swiss National Science Foundation (Grant No. CRSK-2 190731/1). R.P. acknowledges support from the Spanish MINECO (Grant No. MAT2017-83273-R) and from the Ministerio de Ciencia e Innovación (MICINN) through the “María de Maeztu” Programme for Units of Excellence in R&D (Grant No. CEX2018-000805-M). R.G. acknowledges funding from the MICINN (Grant No. PID2019-106801GB-I00) and Comunidad de Madrid Grant No. S2018/NMT-4443 (Tec4Bio-CM). We thankfully acknowledge the computer resources, technical expertise, and assistance provided by the Red Española de Supercomputación (RES) at the Minotauro and CTE-Power9 supercomputers (BSC, Barcelona). We thank Dr. Alejandro Martín-González for fruitful discussion

Registro de herpetofauna presente en isla palma, pacifico colombiano

A nivel mundial los anfibios y los reptiles son los grupos de fauna que despiertan mayor curiosidad dada la velocidad a la que se extinguen; según (LYNCH y RENJIFO, 2001) esto es consecuencia de los cambios efectuados por el hombre sobre su entorno. En Colombia la continua alteración y reducción de los ecosistemas naturales, tiene como consecuencia la disminución de la diversidad biológica afectando negativamente a reptiles y anfibios (ACOSTA, 2000). Estos factores justifican la necesidad de realizar inventarios, registros o reportes de herpetofauna en áreas protegidas, con potencialidad de uso o que alberguen especies de importancia ecológica como lo es Isla Palma (Latitud 3°54'6.99"N, Longitud 77°21'24.46"O). Según (RICKLEFS, 1996) los ecosistemas insulares basan su riqueza de especies de acuerdo a su distancia al continente al transporte pasivo o activo de organismos. Dado que los estudios en la isla se han enfocado hacia el componente marino, como ejemplo de ello encontramos las investigaciones de abundancias de gasterópodos (CUELLAR, 2001), (GIRALDO, 1995), estructuras de comunidades en las zonas intermareales (HERRERA, 2003) y estudios de ecosistemas costeros (CANTERA et al., 1993) entre otros; en este documento se realiza un reporte general de anfibios y reptiles que se encuentren en Isla Palma, contribuyendo con una base de conocimiento histórico para futuras investigaciones en este campo

Uso de suplementos nutricionales y ayudas ergogénicas en jugadores profesionales de tenis.

Introduction: Nutritional supplements and ergogenic aids (NS&EA) are used between training/matches with the goal of enhancing tennis performance. Scientific literature about prevalence and use of NS&EA in professional tennis players is scarce. Objective: The aim of the study was to describe the NS&EA used by professional tennis players during a season. Methods: Using a validated self-administered questionnaire, 62 professional male and 9 professional female tennis players (11% in their gender specific top 100 tennis world ranking (i.e., ATP/WTA)) registered all the used NS&EA. Results: Eighty-one percent of the participants declared taking at least one NS&EA. Strength and conditioning trainers (S&C) and tennis coaches were the professionals who recommended most of the NS&EA in the players outside the TOP-100 (OT100; 50.7% and 39.1%, respectively). However, sports nutritionist were the principal advisors in the top-100 tennis players (T100; 62.5%). Sports drinks were the NS&EA most commonly used by all participants (81.7%). T100 participants used caffeine (p = 0.042), creatine (p = 0.001), iron (p = 0.013) and CHO-protein mix (p = 0.033) significantly more frequently that OT100 players. Conclusions: There is a high prevalence of NS&EA use among professional tennis players independently of their tennis ranking position. However, T100 tennis player have an increased use of certain substances such us caffeine, creatine, iron and CHO-Protein mix. For the rest of the studied NS&EA the use was similar between T100 and OT100 players. It is possible that the differences in NS&EA use between groups could be related to the different professionals on charge of nutritional advice in T100 vs OT100.Introducción: los suplementos nutricionales/ayudas ergogénicas (NS&EA) son utilizados en los entrenamientos/partidos de tenis con el objetivo de mejorar el rendimiento. Sin embargo, la literatura científica se encuentras escasos documentos científicos sobre el uso de estas sustancias en tenistas profesionales. Objetivo: describir el uso de NS&EA utilizados por tenistas profesionales durante una temporada. Métodos: se utilizó un cuestionario validado y se evaluó a 62 tenistas profesionales hombres y 9 mujeres (11% entre los 100 mejores del mundo). Resultados: el 81% de los participantes toman al menos un NS&EA. Los preparadores físicos (S&C) y entrenadores de tenis fueron los profesionales preferidos para recomendar NS&EA entre los jugadores fuera del TOP-100 (OT100, 50,7% y 39,1%, respectivamente). Sin embargo, los nutricionistas deportivos fueron los principales asesores de los jugadores entre los 100 mejores del mundo (T100, 62,5%). Las bebidas deportivas fueron los NS&EA más utilizados entre todos los participantes (81,7%). Los tenistas T100 utilizaron cafeína (p = 0,042), creatina (p = 0,001), hierro (p = 0.013) y mezcla de CHO-proteína (p = 0,033) significativamente más frecuentemente que los jugadores OT100. Conclusiones: existe una gran prevalencia de uso de NS&EA entre los tenistas profesionales. Además, los T100 presentan un mayor uso de ciertas sustancias tales como cafeína, creatina, hierro y CHO-proteína. Para el resto de los NS&EA estudiados, el uso fue similar entre los jugadores T100 y OT100. Finalmente, las diferencias en el uso de NS&EA entre grupos pudieran estar relacionadas con los diferentes profesionales escogidos para el asesoramiento nutricional en T100 vs. OT100.post-print691 K

Quantum reactive scattering calculations of cross sections and rate constants for the N(2D) + O2(X3Σg-) → O(3Π) + NO(X2Π) reaction

Time-dependent quantum wavepacket calculations have been performed on the two lowest adiabatic potential energy surfaces (2 2A´ and 1 2A˝) for the N(2D) + O2(X3Σg-) → O(3Π) + NO(X2Π) reaction. The calculations have been carried out, on these recently published potential energy surfaces, using the real wavepacket method together with a new dispersion fitted finite difference technique for evaluating the action of the radial kinetic energy operator. Reaction probabilities, corresponding to the O2 reactant in its ground vibrational-rotational state, have been calculated for both surfaces and for many different values of the total angular momentum quantum number (J), within the helicity decoupling approximation. The reaction probabilities associated with all other relevant J values have been interpolated, and to a smaller extent extrapolated, using a capture model, to yield probabilities as a function of energy. The probabilities have in turn been summed to yield energy dependent cross sections and then used to compute rate constants. These rate constants are compared with ones obtained from quasiclassical trajectory (QCT) and variational transition state theory (VTST) calculations performed on the same surfaces. There is a good agreement between the wavepacket and QCT cross sections for reaction on both potential energy surfaces considered, with the exception of the near threshold region, where the reaction probability is dominated by tunnelling. Comparison of the predicted rate constants shows that for the 2 2A´ surface, above 300 K, the wavepacket, QCT and VTST results are quite similar. For the 1 2A˝ surface, however, significant differences occur between the wavepacket and the other methods. These differences become smaller with increasing temperature. It is likely that these differences arise, at least in part, from the fact that, when calculating the rate constants, the reactants are restricted to be in their lowest vibrational-rotational state in the wavepacket calculations but are selected from a thermally equilibrated population in the other methods

Sistemas electorales y apoyo electoral de los partidos regionalistas en Europa Occidental

El principal objetivo de este artículo consiste en analizar los efectos de los sistemas electorales sobreel apoyo electoral de los partidos regionalistas en Europa Occidental, durante el periodo 1980-2004.Con esta finalidad, hemos estudiado la fuerza electoral de 30 partidos regionalistas en eleccioneslegislativas. Solamente aquellos partidos que —en términos medios— consiguen más del 1% delvoto regional en el periodo estudiado son incluidos en el análisis. Los sistemas electorales han sidocomúnmente definidos en términos de tres componentes principales: la estructura del voto, la magnitudde la circunscripción y la fórmula electoral. En concreto, hemos considerado el efecto de estostres elementos sobre el grado de multipartidismo y sobre el apoyo electoral de los partidos regionalistas.A su vez los datos electorales han sido analizados a nivel de distrito. El análisis empírico de1.622 procesos electorales sugiere dos conclusiones principales: los sistemas proporcionales tiendena favorecer el multipartidismo, pero no tenemos evidencia empírica de que éstos incrementen elapoyo electoral y representación parlamentaria de los partidos regionalistas

Functional ecology of soil microbial communities along a glacier forefield in Tierra del Fuego (Chile)

A previously established chronosequence from Pia Glacier forefield in Tierra del Fuego (Chile) containing soils of different ages (from bare soils to forest ones) is analyzed. We used this chronosequence as framework to postulate that microbial successional development would be accompanied by changes in functionality. To test this, the GeoChip functional microarray was used to identify diversity of genes involved in microbial carbon and nitrogen metabolism, as well as other genes related to microbial stress response and biotic interactions. Changes in putative functionality generally reflected succession-related taxonomic composition of soil microbiota. Major shifts in carbon fixation and catabolism were observed, as well as major changes in nitrogen metabolism. At initial microbial dominated succession stages, microorganisms could be mainly involved in pathways that help to increase nutrient availability, while more complex microbial transformations such as denitrification and methanogenesis, and later degradation of complex organic substrates, could be more prevalent at vegetated successional states. Shifts in virus populations broadly reflected changes in microbial diversity. Conversely, stress response pathways appeared relatively well conserved for communities along the entire chronosequence. We conclude that nutrient utilization is likely the major driver of microbial succession in these soils. [Int Microbiol 19(3):161-173 (2016)]Keywords: Functional genes · antibiotic resistance · GeoChip microarray · primary succession · chronosequenc

Definition and Empirical Evaluation of Voters for Redundant Smart Sensor Systems Definición y Evaluación Empírica de Algoritmos de Voteo para Sistemas Redundantes de Sensado Inteligente

Abstract This study is the first attempt for integration voting algorithms with fault diagnosis devices. Voting algorithms are used to arbitrate between the results of redundant modules in fault-tolerant systems. Smart sensors are used for FDI (Fault Detection and Isolation) purposes by means of their built in intelligence. Integration of fault masking and FDI strategies is necessary in the construction of ultra-available/safe systems with on-line fault detection capability. This article introduces a range of novel software voting algorithms which adjudicate among the results of redundant smart sensors in a Triple Modular Redundant (TMR) system. Techniques to integrate replicated smart sensors and fault masking approach are discussed, and a classification of hybrid voters is provided based on result and confidence values, which affect the metrics of availability and safety.Thus, voters are classified into four groups: Independent-diagnostic safety-optimised voters, Integrated-diagnostic safety-optimised voters, Independent-diagnostic availability-optimised voters and Integrated-diagnostic availability-optimised voters. The properties of each category are explained and sample versions of each class as well as their possible application areas are discussed. Keywords: Ultra-Available System, Smart Sensor, Fault Masking, Triple Modular Redundancy. Resumen Este estudio es una primer aproximación para la integración de algoritmos de voteo con dispositivos de diagnóstico de fallas. Los algoritmos de voteo son usados para arbitrar entre los resultados de elementos redundantes en sistemas tolerantes a fallas. Los sensores inteligentes son usados para propositos de detección y separación de fallas (FDI) dada la capacidad su capacidad de inteligencia construida. La integración de enmascaramiento de fallas y las estrategias de FDI is necesaria en la construcción de sistemas altamente disponibles y seguros con la capacidad de detección de fallas en línea. Este artículo introduce un rango de algoritmos de voteo los cuales adjudican un resultado entre los resultados generados por los sensores inteligentes en un módulo de redundancia triple. Las técnicas para integrar los sensores inteligentes replicados y la aproximación de enmascaramiento de fallas son revisadas en este artículo. Una clasificación de algoritmos de voteo híbrido es provista con base en el resultado y los valores de confianza los cuales afectan las métricas de disponibilidad y seguridad de estos algoritmos. De hecho los algoritmos de voteo son clasificados en cuatro grupos: Diagnóstico-Independiente con seguridad-optimizada, Diagnóstico-Integrado con seguridad-optimizada, Diagnóstico-Independiente con disponibilidad-opitimizada y Diagnóstico-Integrado con disponibilidad-optimizada. Las propiedades de cada categoria son revisadas asi como muestras de sus implementaciones son discutidas

Morphology and Sequence Data of Mexican Populations of the Ciliate Parasite of Marine Fishes Trichodina rectuncinata (Ciliophora: Trichodinidae)

Trichodina rectuncinata is one of the trichodinids most widely distributed in marine fish. This ciliate species has been recorded in more than 20 host species belonging to 17 fish families worldwide. Previous comparative studies based on morphometric data revealed considerable morphological variation among specimens from different populations of T. rectuncinata. In this study, we conducted a morphometric- molecular analysis of three populations of T. rectuncinata to evaluate potential differences among 18S rRNA sequences, in relation to morphological variations. Smears were obtained from marine fishes in three localities along the Pacific coast of Mexico. Based on the shape of denticles, we found four different morphotypes for T. rectuncinata. This morphological variability does not correspond with the genetic divergence, suggesting that all analyzed populations belong to the same species. Further analyses using more variable markers are necessary to corroborate the findings of our study.Fil: Islas Ortega, Alma G.. Universidad Nacional Autónoma de México; MéxicoFil: Aguilar Aguilar, Rogelio. Universidad Nacional Autónoma de México; MéxicoFil: Marcotegui, Paula Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Estudios Parasitológicos y de Vectores. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Estudios Parasitológicos y de Vectores; ArgentinaFil: Martorelli, Sergio Roberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Estudios Parasitológicos y de Vectores. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Estudios Parasitológicos y de Vectores; ArgentinaFil: Hernández Mena, David. Universidad Nacional Autónoma de México; MéxicoFil: Pérez Ponce de León, Gerardo. Universidad Nacional Autónoma de México; Méxic

Morphology and Sequence Data of Mexican Populations of the Ciliate Parasite of Marine Fishes Trichodina rectuncinata (Ciliophora: Trichodinidae)

Trichodina rectuncinata is one of the trichodinids most widely distributed in marine fish. This ciliate species has been recorded in more than 20 host species belonging to 17 fish families worldwide. Previous comparative studies based on morphometric data revealed considerable morphological variation among specimens from different populations of T. rectuncinata. In this study, we conducted a morphometric- molecular analysis of three populations of T. rectuncinata to evaluate potential differences among 18S rRNA sequences, in relation to morphological variations. Smears were obtained from marine fishes in three localities along the Pacific coast of Mexico. Based on the shape of denticles, we found four different morphotypes for T. rectuncinata. This morphological variability does not correspond with the genetic divergence, suggesting that all analyzed populations belong to the same species. Further analyses using more variable markers are necessary to corroborate the findings of our study.Centro de Estudios Parasitológicos y de Vectore