Amino acid metabolism conflicts with protein diversity Krick, Teresa Elena Genoveva; Verstraete, Nina; Alonso, Leonardo Gabriel; Shub, David A.; Ferreiro, Diego; Shub, Michael Ira; Sánchez Miguel, Ignacio Enrique The 20 protein-coding amino acids are found in proteomes with different relative abundances. The most abundant amino acid, leucine, is nearly an order of magnitude more prevalent than the least abundant amino acid, cysteine. Amino acid metabolic costs differ similarly, constraining their incorporation into proteins. On the other hand, a diverse set of protein sequences is necessary to build functional proteomes. Here, we present a simple model for a cost-diversity trade-off postulating that natural proteomes minimize amino acid metabolic flux while maximizing sequence entropy. The model explains the relative abundances of amino acids across a diverse set of proteomes. We found that the data are remarkably well explained when the cost function accounts for amino acid chemical decay. More than 100 organisms reach comparable solutions to the trade-off by different combinations of proteome cost and sequence diversity. Quantifying the interplay between proteome size and entropy shows that proteomes can get optimally large and diverse.

Hyphoderma romeroae sp. nov., a valid name for “Mutatoderma brunneocontextum” (Basidiomycota, Polyporales) Baltazar, Juliano M.; Rajchenberg, Mario Hyphoderma romeroae sp. nov. es propuesto para la especie “Mutatoderma brunneocontextum” C.E. Gómez que fuera inválidamente publicada previamente.; Hyphoderma romeroae sp. nov. is proposed for the species previously invalidly named as “Mutatoderma brunneocontextum” C.E. Gómez.

Numerical Simulations of Stick Percolation: Application to the Study of Structured Magnetorheological Elastomers Mietta, J. L.; Negri, Ricardo Martin; Tamborenea, Pablo Ignacio In this article we explore how structural parameters of composites filled with one-dimensional, electrically conducting elements (such as sticks, needles, chains, or rods) affect the percolation properties of the system. To this end, we perform Monte Carlo simulations of asymmetric two-dimensional stick systems with anisotropic alignments. We compute the percolation probability functions in the direction of preferential orientation of the percolating objects and in the orthogonal direction, as functions of the experimental structural parameters. Among these, we considered the average length of the sticks, the standard deviation of the length distribution, and the standard deviation of the angular distribution. We developed a computer algorithm capable of reproducing and verifying known theoretical results for isotropic networks and which allows us to go beyond and study anisotropic systems of experimental interest. Our research shows that the total electrical anisotropy, considered as a direct consequence of the percolation anisotropy, depends mainly on the standard deviation of the angular distribution and on the average length of the sticks. A conclusion of practical interest is that we find that there is a wide and well-defined range of values for the mentioned parameters for which it is possible to obtain reliable anisotropic percolation under relatively accessible experimental conditions when considering composites formed by dispersions of sticks, oriented in elastomeric matrices.

UV–Vis spectroscopic study and DFT calculation on the solvent effect of trimethoprim in neat solvents and aqueous mixtures Almandoz, M. C.; Sancho, Matias Israel; Duchowicz, Pablo Román; Blanco, Sonia Encarnacion The solvatochromic behavior of trimethoprim (TMP) was analyzed using UV–Vis spectroscopy and DFT methods in neat and binary aqueous solvent mixtures. The effects of solvent dipolarity/polarizability and solvent–solute hydrogen bonding interactions on the absorption maxima were evaluated by means of the linear solvation energy relationship concept of Kamlet and Taft. This analysis indicated that both interactions play an important role in the position of the absorption maxima in neat solvents. The simulated absorption spectra of TMP and TMP:(solvent)n complexes in ACN and H2O using TD-DFT methods were in agreement with the experimental ones. Binary aqueous mixtures containing as co-solvents DMSO, ACN and EtOH were studied. Preferential solvation was detected as a nonideal behavior of the wavenumber curve respective to the analytical mole fraction of co-solvent in all binary systems. TMP molecules were preferentially solvated by the organic solvent over the whole composition range. Index of preferential solvation, as well as the influence of solvent parameters were calculated as a function of solvent composition.

Cooperativity to increase Turing Pattern space for synthetic biology Diambra, Luis Anibal; Senthivel, Vivek Raj; Barcena Menendez, Diego; Isalan, Mark It is hard to bridge the gap between mathematical formulations and biological implementations of Turing patterns, yet this is necessary for both understanding and engineering these networks with synthetic biology approaches. Here, we model a reaction–diffusion system with two morphogens in a monostable regime, inspired by components that we recently described in a synthetic biology study in mammalian cells.1 The model employs a single promoter to express both the activator and inhibitor genes and produces Turing patterns over large regions of parameter space, using biologically interpretable Hill function reactions. We applied a stability analysis and identified rules for choosing biologically tunable parameter relationships to increase the likelihood of successful patterning. We show how to control Turing pattern sizes and time evolution by manipulating the values for production and degradation relationships. More importantly, our analysis predicts that steep dose–response functions arising from cooperativity are mandatory for Turing patterns. Greater steepness increases parameter space and even reduces the requirement for differential diffusion between activator and inhibitor. These results demonstrate some of the limitations of linear scenarios for reaction–diffusion systems and will help to guide projects to engineer synthetic Turing patterns.

Efecto de la precipitación sobre la dinámica hidrológica de las lagunas de la cuenca inferior del Río Colorado (período 1981-2011) Aliaga, Vanina Solange; Bohn, Vanesa Yael; Piccolo, Maria Cintia; Perillo, Gerardo Miguel E. The purpose of this study was to analyze the temporal dynamics of shallow lakes during the 2002-2012 years in the Colorado River Basin in relation to climate variability. Dry and humid periods were identified by water balance. Moreover, the influence of the extreme rainfall events on the shallow lakes in the region was analyzed. Shallow lakes area was estimated during three different years by satellite image processing (LANDSAT 5TM y 7 ETM). Water bodies were classified according to geomorphological, hydrological and morphometric criteria during a normal period. According rainfall amounts, 2011, 2004 and 2008 were considered normal, wet and dry years, respectively. As a result, 15 (normal), 20 (wet), and 5 (dry) shallow lakes which covered an area of 13.05, 14.54, and 5.8 km2 respectively were detected. A correlation between the area covered by water and the annual precipitation was obtained in the study area. As a result of the clustering method application, 3 groups of water bodies were defined. The first included the biggest and permanent water bodies (area > 1.5 km2). Group 2 included salt shallow lakes which Total Maximum Length (TML) orientation was N-S. The remaining group was composed by lakes located in the wettest area of the basin with an E-W LMT orientation.

Phase and amplitude measurements for high bandwidth optical signals Bulus Rossini, Laureano Andrés; Costanzo Caso, Pablo Alejandro; Paulucci, Emanuel; Duchowicz, Ricardo; Sicre, Enrique Eduardo In this paper a novel technique for obtaining the amplitude and phase of optical pulses with time extents as short as tens of ps is presented. The method which is based on the transport-of-intensity equation only requires, for a practical realization, of passive fiber optic devices. It employs as the main component a dispersive element with a known second order dispersion coefficient. Two different setup implementations are considered, for which simulations are carried out in order to test the method performance taking into account both, realizable models of the involved devices and typical pulses found in optical transmission systems. The characterization of optical pulses affected by dispersion and nonlinear effects, such as self-phase modulation, is used to evaluate the performance of the method and show the practical feasibility of the future implementation.

Nonlinear Control of a Buck Converter Feeding a Constant Power Load Solsona, Jorge Alberto; Gómez Jorge, Sebastián; Busada, Claudio In this paper a nonlinear control strategy for controlling a dc/dc Buck converter feeding a constant power load is proposed. A feedback controller is combined with a feedforward strategy. A nonlinear reduced order observer is used for estimating the value of the power load and its time derivative. These estimated values are fed forward to the nonlinear feedback controller whose design is based on feedback linearization method. The proposed controller is tested via simulations and also, experimental results are presented.

Measurement of cooling and warming rates in vitrification-based plant cryopreservation protocols Schneider Teixeira, Aline; Gonzalez Benito, M. Elena; Molina García, Antonio D. Cryopreservation protocols include the use of additives and pre-treatments aimed to reduce the probability of ice nucleation at all temperatures, mainly through micro-viscosity increase. Still, there is a risk of ice formation in the temperature region comprised between the equilibrium freezing (Tf) and the glass transition (TG) temperatures. Consequently, fast cooling and warming, especially in this region, is a must to avoid ice-derived damage. Vitrification and droplet-vitrification techniques, frequently used cryopreservation protocols based in fast cooling, were studied, alongside with the corresponding warming procedures. A very fast data acquisition system, able to read very low temperatures, down to that of liquid nitrogen, was employed. Cooling rates, measured between -20 and -120 ºC, ranged from ca. 5 ºC s-1 to 400 ºC s-1, while warming rates spanned from ca. 2 ºC s-1 to 280 ºC s-1, for the different protocols and conditions studied. A wider measuring window (0 ºC to -150 ºC) produced lower rates for all cases. The cooling and warming rates were also related to the survival observed after the different procedures. Those protocols with the faster rates yielded the highest survival percentages.

BMO spaces related to Laguerre semigroups Harboure, Eleonor Ofelia; Chicco Ruiz, Anibal Leonardo For the system of Laguerre functions inline image we define a suitable BMO space from the atomic version of the Hardy space inline image considered by Dziubański in [7], where inline image is the maximal operator of the heat semigroup associated to that Laguerre system. We prove boundedness of inline image over a weighted version of that BMO, and we extend such result to other systems of Laguerre functions, namely inline image and inline image. To do that, we work with a more general family of weighted BMO-like spaces that includes those associated to all of the above mentioned Laguerre systems. In this setting, we prove that the local versions of the Hardy-Littlewood and the heat-diffusion maximal operators turn to be bounded over such family of spaces for inline image weights. This result plays a decisive role in proving the boundedness of Laguerre semigroup maximal operators.

Inverse expression of estrogen receptor alpha and apolipoprotein B in coronary intimal hyperplasia of surgically repaired congenital heart disease: A pre-atherosclerotic condition? Castilla Lozano, Maria del Rocio; Cao, Gabriel Fernando; Kolliker Frers, Rodolfo Alberto; Muller, Angelica del Carmen; Ambrosio, Giuseppe; Milei, Jose Congenital heart diseases (CHD) or the process of their repair leads to an increased risk for adult cardiovascular disease compared with the general population. The proliferation of intimal smooth muscle cells (SMCs), which causes intimal thickenings prior to any evidence of visible lipid deposition, was proposed to be the initial lesion of coronary atherosclerosis. The increasing trend to consider intimal thickenings as possible pre-atherosclerotic lesions is based on the distribution of intimal hyperplasia in children and the localization of characteristic atherosclerotic lesions observed in adult humans. Early coronary artery lesions may range from focal areas with mild myointimal thickenings in prenatal life to early soft plaques in infants, which may also present as intermingled lesions with components of both categories, more frequently observed with increasing age. Also,we proposed that TGF-β1 expressionmight be considered another possible predisposing factor to develop atherosclerotic coronary artery disease in CHD patients. On the other hand, estrogen receptor-α (ERα) appears to be responsible for the protective effects of estrogens against atherosclerotic vascular disease. The aim of this paper was to analyze the immunohistochemical expression of ERα, TGF-β1 and apolipoprotein B in coronary intimal hyperplasia in children with CHD and the possible increased risk for the development pre-atherosclerotic lesions.

Numerical integration of the stochastic Landau-Lifshitz-Gilbert equation in generic time-discretization schemes Romá, Federico José; Cugliandolo, Leticia F.; Lozano, Gustavo Sergio We introduce a numerical method to integrate the stochastic Landau-Lifshitz-Gilbert equation in spherical coordinates for generic discretization schemes. This method conserves the magnetization modulus and ensures the approach to equilibrium under the expected conditions. We test the algorithm on a benchmark problem: the dynamics of a uniformly magnetized ellipsoid. We investigate the influence of various parameters, and in particular, we analyze the efficiency of the numerical integration, in terms of the number of steps needed to reach a chosen long-time with a given accuracy.

Carma Large Area Star Formation Survey: observational analysis of filaments in the serpens south molecular cloud Fernandez Lopez, Manuel; Arce, H. G.; Looney, Leslie W.; Mundy, Lee G.; Storm, S.; Teuben, P. J. ; Lee, K.; Segura Cox, Dominique M.; Isella, A.; Tobin, John J.; Rosolowsky, E.; Plunkett, A. ; Kwon, Woojin; Kauffmann, J.; Ostriker, E. ; Tassis, K.; Shirley, Y. L.; Pound, M. We present the N2H+ (J = 1 → 0) map of the Serpens South molecular cloud obtained as part of the CARMA Large Area Star Formation Survey. The observations cover 250 arcmin2 and fully sample structures from 3000 AU to 3 pc with a velocity resolution of 0.16 km s−1, and they can be used to constrain the origin and evolution of molecular cloud filaments. The spatial distribution of the N2H+ emission is characterized by long filaments that resemble those observed in the dust continuum emission by Herschel. However, the gas filaments are typically narrower such that, in some cases, two or three quasi-parallel N2H+ filaments comprise a single observed dust continuum filament. The difference between the dust and gas filament widths casts doubt on Herschel ability to resolve the Serpens South filaments. Some molecular filaments show velocity gradients along their major axis, and two are characterized by a steep velocity gradient in the direction perpendicular to the filament axis. The observed velocity gradient along one of these filaments was previously postulated as evidence for mass infall toward the central cluster, but these kind of gradients can be interpreted as projection of large-scale turbulence.

Pliocene Orographic Barrier Uplift in the Southern Central Andes Pingel, Heiko; Alonso, Ricardo Narciso; Mulch, Andreas; Rohrmann, Alexander; Sudo, Masafumi; Strecker, R. Sedimentary basin fills along the windward flanks of orogenic plateaus are valuable archives of paleoenvironmental change with the potential to resolve the history of surface uplift and orographic barrier formation. The intermontane basins of the southern Central Andes contain thick successions of sedimentary material that are commonly interbedded with datable volcanic ashes. We relate variations in the hydrogen isotopic composition of hydrated volcanic glass (δDg) of Neogene to Quaternary fills in the semiarid intermontane Humahuaca Basin (Eastern Cordillera, northwest Argentina) to spatiotemporal changes in topography and associated orographic effects. δD values from volcanic glass in the basin strata (–117‰ to –98‰) show two main trends that accompany observed tectonosedimentary events in the study area. Between 6.0 and 3.5 Ma, δDg values decrease by ∼17‰; this is associated with surface uplift in the catchment area. After 3.5 Ma, δDg values show abrupt deuterium enrichment, which we associate with (1) the attainment of threshold elevations for blocking moisture transport in the basin-bounding ranges to the east, and (2) the onset of semiarid conditions in the basin. Such orographic barriers throughout the eastern flanks of the Central Andes have impeded moisture transport into the orogen interior; this has likely helped maintain aridity and internal drainage conditions on the adjacent Andean Plateau.

A multilocus perspective on the phylogenetic relationships and diversification of rodents of the tribe Abrotrichini (Cricetidae: Sigmodontinae) Cañón Valenzuela, Carola Patricia; Mir, Daiana; Pardiñas, Ulises Francisco J.; Lessa, Enrique P.; D´Elía, Guillermo Abrotrichini is a recently defined and diagnosed tribe of Sigmodontinae with a complex taxonomy. Abrotrichine genera, Abrothrix (including Chroeomys), Chelemys, Geoxus, Notiomys and Pearsonomys, are mostly distributed in the central and southern Andes and adjacent lowlands and show terrestrial and fossorial habits. Recent studies have evidenced some incongruence between current taxonomy and abrotrichine phylogeny, such as the polyphyly of Chelemys and paraphyly of Geoxus respect to Pearsonomys. We used DNA sequence data of six loci (one mitochondrial and five nuclear) to resolve the relationships within the tribe. Independent and combined analyses of these loci were carried out using parsimony, maximum likelihood and Bayesian inference. Estimates of divergence time of the main lineages of abrotrichines were calculated with a molecular clock using as calibration, a fossil recently found. The concatenated data set increased the resolution and defined the relationships within the tribe. Our phylogenetic analyses corroborate that Abrothrix is sister of a clade containing the long-clawed abrotrichines. We recovered two main clades within Abrothrix that match morphologic variation and geographic distribution of its species. In addition, we corroborated the lack of monophyly of Chelemys and the lack of monophyly of Geoxus. We discuss different taxonomic scenarios to abrotrichine classification reflects the phylogenetic relationships obtained in this study. Our molecular clock estimated the Abrotrichini crown age to be around the early Pliocene (4.4 Ma) and suggest that the tribe diversified over a short period of time.

Microfungal composition in an Astellia-Donatia cushion peatland in Tierra del Fuego, Argentina Paredes, Noelia Ivana; Consolo, Verónica Fabiana; Pancotto, Veronica Andrea; Fritz, Christian; Barrera, Marcelo Daniel; Arambarri, Angélica Margarita; Salerno, Graciela Lidia Southern Hemisphere peatlands store substantial amounts of soil carbon. Despite their importance in the global carbon cycle, little is known about decomposition processes and the associated fungal diversity. The present study describes the composition of fungal assemblage in two depths from a cushion peatland of predominating Astelia (Asteliaceae) and Donatia (Donatiaceae) species in Moat, Tierra del Fuego. From 48 samples processed, we obtained 338 isolates. Using different culturing methodologies, through direct and microscopic observation and using molecular methods we identified 38 fungal species and 18 genera of Ascomycetes and Zygomycetes. Isolates belonging to Ascomycetes were the most abundant, with dominance of Penicillium and Trichoderma. We described fungal composition and compared species diversity and evenness across two dephts. No differences in the diversity index and evenness were found between depths. The studied peat is an ecosystem that has a great diversity of filamentous fungal species, some of which are described in other peatlands worldwide.

Interannual variations in primary and secondary growth of Nothofagus pumilio and their relationships with climate Magnin, Noel Amaru; Puntieri, Javier Guido; Villalba, Ricardo The relationships between apical (or primary) and radial (or secondary) growth, and climatic influences on both types of growth, were evaluated for Nothofagus pumilio (Nothofagaceae), the dominant subalpine tree in Patagonia. We measured the spacing and number of nodes of annual shoots developed in the period 2001-2010 in 40 N. pumilio trees growing near the upper treeline in the northern Patagonian Andes (41ºS). Variations in ring width at the base of each trunk were also recorded. Interannual variations in primary and secondary growth were significantly related to each other, and to several climate variables. Mean temperatures in winter and early spring (June to October) prior to the period of shoot extension were positively associated with both primary and secondary growth. In addition, total summer precipitation (December to March) was positively related to shoot extension, whereas mean summer temperature during the previous growth season (January to March) was directly related to radial growth. These climatic influences on N. pumilio growth may play a major role in regulating the expressions of preformation and neoformation.

Plant functional traits and phylogenetic relatedness explain variation in associations with root fungal endophytes in an extreme arid environment Lugo, Mónica Alejandra; Reinhart, Kurt O.; Menoyo, Eugenia; Crespo, Esteban María; Urcelay, Roberto Carlos Since root endophytes may ameliorate drought stress, understanding which plants associate with endophytes is important, especially in arid ecosystems. Here, the root endophytes were characterized of 42 plants from an arid region of Argentina. Colonization by arbuscular mycorrhizal fungi (AMF) and dark septate endophytes (DSEs) was related to plant functional type (PFT), family, and phylogenetic relatedness. Overall, three main findings were observed. Firstly, only moderate levels of endophyte associations were found across all taxa (e.g., most Poaceae were not colonized by endophytes despite numerous accounts of colonization by AMF and DSEs). We determined 69 % of plant taxa associated with some form of root endophyte but levels were lower than other regional studies. Secondly, comparisons by PFT and phylogeny were often qualitatively similar (e.g., succulents and Portulacineae consistently lacked AMF; variation occurred among terrestrial vs. epiphytic bromeliads) and often differed from comparisons based on plant family. Thirdly, comparisons by plant family often failed to account for important variation either within families (e.g., Bromeliaceae and Poaceae) or trait conservatism among related families (i.e., Rosidae consistently lacked DSEs and Portulacineae lacked AMF). This study indicates the value of comparing numerous taxa based on PFTs and phylogenetic similarity. Overall, the results suggest an uncertain benefit of endophytes in extremely arid environments where plant traits like succulence may obviate the need to establish associations.

The Future of Philosophy of History from its Narrativist Past: Figuration, Middle Voice Writing and Performativity la Greca, María Inés Hayden White inaugurated narrativism in philosophy of history when he effected a productive displacement of earlier epistemological discussions around the relationship between narration and historical knowledge: White identified the problem of narrative in history with the problem of the use of figurative language in the representation of the past. Thus, he enabled a new way of thinking philosophy of history’s object of study by paying attention to an aspect of historical practice he considered wrongly overlooked: the writing of history. His formal theory of the historical work needs no introduction. Instead, this paper aims at reclaiming the fundamental philosophical legacy White has left us in his latest work on middle voice writing.  First, I will frame White’s thought as a response to what I call the paradoxical nature of historical narrative, as Louis Mink and Roland Barthes understand it. By presenting our narrativist past as White’s ironical and liberating stance on historical narrative, I will show how he identified figuration as the paradoxical resource and constrain of historical writing. Secondly, I will elaborate on his latest inquiries into middle voice writing as pointing the way into the future of philosophy of history. Thus, I will claim that the notion of middle voice writing that White adopted from Roland Barthes should be read from the point of view of performativity theory in order to reassess the philosophical nature of historical writing now considered as the performative self-constitution of the historical subject.

El pasajero oscuro. Elucubraciones sobre Dexter; The dark passenger. Musings about Dexter Murolo, Norberto Leonardo El trabajo propone tópicos de reflexión sobre la serie televisiva Dexter, emitida por el canal Showtime. Como narración proveniente de la industria cultural estadounidense su éxito llevó a que se difundiera en todo el mundo y que sus fans se multiplicaran. La serie tematiza la historia de un asesino serial diferente a los del cine hollywoodense. Dexter no quiere ser quien es y lucha contra una parte de él mismo que tiene como impulso matar; como él lo llama: su pasajero oscuro. En medio de esa historia se entrecruzan múltiples temas que tocan a la condición humana. El mal y el bien, la justicia y la injusticia, los héroes y los antihéroes son cuestiones constantes en la serie. Asimismo, las relaciones familiares, sobre todo entre el personaje protagónico y su hermana, son centrales a la hora de decodificar este discurso que, gracias a las tecnologías digitales, cuenta con adeptos de todo el mundo.; This paper proposes topics of reflection on the Showtime television series, Dexter. As a narrative from the American cultural industry, success led it to spread throughout the world, multiplying its fans. The series is about a serial murderer with a different story than the Hollywood ones. Dexter doesn’t want to be who he is and fights against a part of him that has killing as an impulse –his “dark passenger”, as he calls it-. As the story unfolds, multiple threads related to the human condition intersect. The good and evil, justice and injustice, heroes and antiheroes are regular issues in the series. Also, family relationships, especially between the main character and her sister, are essential while decoding this speech that, thanks to digital technologies, has followers all over the world.