Facultad de Ciencias Exactas y Naturales

Publicaciones 2018

Effect of magnetism and temperature on the stability of (Cr-x, V1-x)(2)AlC phases

Grossi, J ;Shah, SH ; Artacho, E ; Bristowe, PD ; PHYSICAL REVIEW MATERIALS ,2018 ,2 ,-.

The stability of (Cr-x, V1-x)(2)AlC MAX phases, materials of interest for a variety of magnetic as well as high-temperature applications, has been studied using density-functional-theory first-principles calculations. The enthalpy of mixing predicts these alloys to be unstable towards unmixing at 0 K. The calculations also predict, however, that these phases would be thermally stabilized by configurational entropy at temperatures well below the values used for synthesis. The temperature T-s below which they become unstable is found to be quite sensitive to the presence of magnetic moments on Cr ions, as well as to the material's magnetic order, in addition to chemical order and composition. Allowing for magnetism, the value of T-s for (Cr-0.5, V-0.5)(2)AlC with chemically disordered Cr and V atoms is estimated to be between 516 and 645 K depending on the level of theory, while if constrained to spin paired, T-s drops to similar to 142 K. Antiferromagnetic spin arrangements are found to be favored. The combination of antiferromagnetic frustration and configurational disorder should give rise to interesting spin textures at low temperatures.

Live imaging of cortical granule exocytosis reveals that in vitro matured mouse oocytes are not fully competent to secrete their content

Cappa, AI ;de Paola, M ; Wetten, P ; De Blas, GA ; Michaut, MA ; BIOLOGY OPEN ,2018 ,7 ,-.

Oocyte in vitro maturation does not entirely support all the nuclear and cytoplasmic changes that occur physiologically, and it is poorly understood whether in vitro maturation affects the competence of cortical granules to secrete their content during cortical reaction. Here, we characterize cortical granule exocytosis (CGE) in live mouse oocytes activated by strontium chloride using the fluorescent lectin FITC-LCA. We compared the kinetic of CGE between ovulated (in vivo matured, IVO) and in vitro matured (IVM) mouse oocytes. Results show that: (1) IVM oocytes have a severely reduced response to strontium chloride; (2) the low response was confirmed by quantification of remnant cortical granules in permeabilized cells and by a novel method to quantify the exudate in non-permeabilized cells; (3) the kinetic of CGE in IVO oocytes was rapid and synchronous; (4) the kinetic of CGE in IVM oocytes was delayed and asynchronous; (5) cortical granules in IVM oocytes show an irregular limit in regards to the cortical granule free domain. We propose the analysis of CGE in live oocytes as a biological test to evaluate the competence of IVM mouse oocytes.

Environmental protection and production of food for self consumption in non irrigated dry lands of Mendoza, Argentina

Sales, RG ;Guida-Johnson, B ; REVISTA DE GEOGRAFIA NORTE GRANDE ,2018 ,,109 -124 .

Drylands degradation is a threat to the well-being of the population living in that territory, which also presents imbalances around the historical polarized configuration between irrigated and non-irrigated lands. In this research we applied a qualitative methodology to study the environmental perceptions of small livestock ranching producers living in the non-irrigated area of Mendoza in order to identify problems related to the access and quality of water and the production of food for self-consumption. We highlight the importance of knowing the environmental perception of the local community to define the conflicts and then carry out specific studies that enable the identification of the causes of degradation. Incorporating the social dimension during the design of the measures to be implemented will allow the public policy to readjust its guidelines to improve the obtained results. In addition, it will enrich the generation of management recommendations.

Reconstruction of endosomal organization and function by a combination of ODE and agent-based modeling strategies

Mayorga, LS ;Cebrian, I ; Verma, M ; Hoops, S ; Bassaganya-Riera, J ; BIOLOGY DIRECT ,2018 ,13 ,-.

BackgroundReproducing cell processes using an in silico system is an essential tool for understanding the underlying mechanisms and emergent properties of this extraordinary complex biological machine. However, computational models are seldom applied in the field of intracellular trafficking. In a cell, numerous molecular interactions occur on the surface or in the interior of membrane-bound compartments that continually change position and undergo dynamic processes of fusion and fission. At present, the available simulation tools are not suitable to develop models that incorporate the dynamic evolution of the cell organelles.ResultsWe developed a modeling platform combining Repast (Agent-Based Modeling, ABM) and COPASI (Differential Equations, ODE) that can be used to reproduce complex networks of molecular interactions. These interactions occur in dynamic cell organelles that change position and composition over the course of time. These two modeling strategies are fundamentally different and comprise of complementary capabilities. The ODEs can easily model the networks of molecular interactions, signaling cascades, and complex metabolic reactions. On the other hand, ABM software is especially suited to simulate the movement, interaction, fusion, and fission of dynamic organelles. We used the combined ABM-ODE platform to simulate the transport of soluble and membrane-associated cargoes that move along an endocytic route composed of early, sorting, recycling and late endosomes. We showed that complex processes that strongly depend on transport can be modeled. As an example, the hydrolysis of a GM2-like glycolipid was programmed by adding a trans-Golgi network compartment, lysosomal enzyme trafficking, endosomal acidification, and cholesterol processing to the simulation model.ConclusionsThe model captures the highly dynamic nature of cell compartments that fuse and divide, creating different conditions for each organelle. We expect that this modeling strategy will be useful to understand the logic underlying the organization and function of the endomembrane system.ReviewersThis article was reviewed by Drs. Rafael Fernandez-Chacon, James Faeder, and Thomas Simmen.

Communication channel occupation and congestion in wireless sensor networks

Godoy, PD ;Cayssials, RL ; Garino, CGG ; COMPUTERS & ELECTRICAL ENGINEERING ,2018 ,72 ,846 -858 .

Wireless sensor networks (WSN) may be composed by tens or hundreds of nodes. Nodes measure variables and send their values to a base station through a shared low data rate wireless communication channel. Communication protocols for WSNs have been developed in order to support a large number of nodes. However, if a great deal of data is transmitted through a low speed communication channel, data packet congestion may happen. Congestion may lead to high latencies or data loss. Data congestion could take place in WSNs with a large number of nodes sending data periodically, or in WSNs where the data rate can increase when a specific event is detected. In this paper we analyze the conditions that lead to congestion of the communication channel considering the following nodes configuration parameters: (1) transmission time intervals, (2) data packet generation rate, and (3) transmitter output power level. (C) 2017 Elsevier Ltd. All rights reserved.

Galectins: Multitask signaling molecules linking fibroblast, endothelial and immune cell programs in the tumor microenvironment

Elola, MT ;Ferragut, F ; Mendez-Huergo, SP ; Croci, DO ; Bracalente, C ; Rabinovich, GA ; CELLULAR IMMUNOLOGY ,2018 ,333 ,34 -45 .

Tumor cells corrupt surrounding normal cells instructing them to support proliferative, pro-angiogenic and immunosuppressive networks that favor tumorigenesis and metastasis. This dynamic cross-talk is sustained by a range of intracellular signals and extracellular mediators produced by both tumoral and non-tumoral cells. Galectins-whether secreted or intracellularly expressed- play central roles in the tumorigenic process by delivering regulatory signals that contribute to reprogram fibroblasts, endothelial and immune cell programs. Through glycosylation-dependent or independent mechanisms, these endogenous lectins control a variety of cellular events leading to tumor cell proliferation, survival, migration, inflammation, angiogenesis and immune escape. Here we discuss the role of galectin-driven pathways, particularly those activated in non-tumoral stromal cells, in modulating tumor progression.

Mechanical Properties Obtained by Indentation of Hollow Pd Nanoparticles

Valencia, FJ ;Gonzalez, RI ; Vega, H ; Ruestes, C ; Rogan, J ; Valdivia, JA ; Bringa, EM ; Kiwi, M ; JOURNAL OF PHYSICAL CHEMISTRY C ,2018 ,122 ,25035 -25042 .

Palladium nanoparticles are technologically important for catalysis, hydrogen storage, and many other applications. Here, we investigate the mechanical properties of Pd hollow nanoparticles of different sizes and thicknesses by means of classical molecular dynamics simulations. Hollow nanospheres of sizes ranging from 5 to 40 nm are compressed using planar indenters. Our results suggest that the mechanical response of hollow nanoparticles can be tailored by tuning the external radius (R) and shell thickness (omega). The largest elastic limit for a given thickness is achieved when the aspect ratio A = R/omega is 3 <= A <= 4. This delay of the onset of plastic deformation is due to the fact that, for this geometry, hollow nanoparticles can buckle, avoiding stress concentration in the contact; this in turn favors stress accumulation and dislocation behavior of solid nanoparticles and "bulk" surfaces.

Isotopic evidence for oligotrophication of terrestrial ecosystems

Craine, JM ;Elmore, AJ ; Wang, LX ; Aranibar, J ; Bauters, M ; Boeckx, P ; Crowley, BE ; Dawes, MA ; Delzon, S ; Fajardo, A ; Fang, YT ; Fujiyoshi, L ; Gray, A ; Guerrieri, R ; Gundale, MJ ; Hawke, DJ ; Hietz, P ; Jonard, M ; Kearsley, E ; Kenzo, T ; Makarov, M ; Maranon-Jimenez, S ; McGlynn, TP ; McNeil, BE ; Mosher, SG ; Nelson, DM ; Peri, PL ; Roggy, JC ; Sanders-DeMott, R ; Song, MH ; Szpak, P ; Templer, PH ; Van der Colff, D ; Werner, C ; Xu, XL ; Yang, Y ; Yu, GR ; Zmudczynska-Skarbek, K ; NATURE ECOLOGY & EVOLUTION ,2018 ,2 ,1735 -1744 .

Human societies depend on an Earth system that operates within a constrained range of nutrient availability, yet the recent trajectory of terrestrial nitrogen (N) availability is uncertain. Examining patterns of foliar N concentrations and isotope ratios (delta N-15) from more than 43,000 samples acquired over 37 years, here we show that foliar N concentration declined by 9% and foliar delta N-15 declined by 0.6-1.6 parts per thousand. Examining patterns across different climate spaces, foliar delta N-15 declined across the entire range of mean annual temperature and mean annual precipitation tested. These results suggest declines in N supply relative to plant demand at the global scale. In all, there are now multiple lines of evidence of declining N availability in many unfertilized terrestrial ecosystems, including declines in delta N-15 of tree rings and leaves from herbarium samples over the past 75-150 years. These patterns are consistent with the proposed consequences of elevated atmospheric carbon dioxide and longer growing seasons. These declines will limit future terrestrial carbon uptake and increase nutritional stress for herbivores.

Genome-Wide Association Study Using Historical Breeding Populations Discovers Genomic Regions Involved in High-Quality Rice

Quero, G ;Gutierrez, L ; Monteverde, E ; Blanco, P ; de Vida, FP ; Rosas, J ; Fernandez, S ; Garaycochea, S ; McCouch, S ; Berberian, N ; Simondi, S ; Bonnecarrere, V ; PLANT GENOME ,2018 ,11 ,-.

Rice (Oryza sativa L.) is one of the most important staple food crops in the world; however, there has recently been a shift in consumer demand for higher grain quality. Therefore, understanding the genetic architecture of grain quality has become a key objective of rice breeding programs. Genome-wide association studies (GWAS) using large diversity panels have successfully identified genomic regions associated with complex traits in diverse crop species. Our main objective was to identify genomic regions associated with grain quality and to identify and characterize favorable haplotypes for selection. We used two locally adapted rice breeding populations and historical phenotypic data for three rice quality traits: yield after milling, percentage of head rice recovery, and percentage of chalky grain. We detected 22 putative quantitative trait loci (QTL) in the same genomic regions as starch synthesis, starch metabolism, and cell wall synthesis-related genes are found. Additionally, we found a genomic region on chromosome 6 in the tropical japonica population that was associated with all quality traits and we identified favorable haplotypes. Furthermore, this region is linked to the OsBEI gene that codes for a starch branching enzyme I, which is implicated in starch granule formation. In tropical japonica, we also found two putative QTL linked to OsBEII, OsDEP1, and OsDEP2. Our study provides an insight into the genetic basis of rice grain chalkiness, yield after milling, and head rice, identifying favorable haplotypes and molecular markers for selection in breeding programs.

Numerical analysis of the influence of inertial loading over morphing trailing edge devices

Tripp, NG ;Mirasso, AE ; Preidikman, S ; JOURNAL OF INTELLIGENT MATERIAL SYSTEMS AND STRUCTURES ,2018 ,29 ,3533 -3549 .

Larger and more flexible wind turbine blades are currently being manufactured. Those highly flexible blades suffer from loading of aeroelastic nature which increases the fatigue damage. Smart blade concepts are being developed to reduce the aerodynamic loading. The state of the art favors the discrete deformable trailing edge concept. Many authors have reported adequate performance of this type of actuators in reducing the blade vibrations. However, the question of whether the actuator can maintain its authority under strong external loading remains still answered. To solve this question, actuator models that include the loading produced by the blade vibration are required. In this article, a smart morphing trailing edge model is presented that includes the inertial forces produced by the blade dynamics. The model is applied to a commercial actuator and the influence of its parameters is analyzed. Finally, a simple estimation of the inertial loading produced by a 35-m wind turbine blade at the flutter instability condition is analyzed to understand the design requirements of this type of systems.

Uniaxial-deformation behavior of ice I-h as described by the TIP4P/Ice and mW water models

Santos-Florez, PA ;Ruestes, CJ ; de Koning, M ; JOURNAL OF CHEMICAL PHYSICS ,2018 ,149 ,-.

Using molecular dynamics simulations, we assess the uniaxial deformation response of ice I-h as described by two popular water models, namely, the all-atom TIP4P/Ice potential and the coarse-grained mW model. In particular, we investigate the response to both tensile and compressive uniaxial deformations along the [0001] and [0 (1) over bar 10] crystallographic directions for a series of different temperatures. We classify the respective failure mechanisms and assess their sensitivity to strain rate and cell size. While the TIP4P/Ice model fails by either brittle cleavage under tension at low temperatures or large-scale amorphization/melting, the mW potential behaves in a much more ductile manner, displaying numerous cases in which stress relief involves the nucleation and subsequent activity of lattice dislocations. Indeed, the fact that mW behaves in such a malleable manner even at strain rates that are substantially higher than those applied in typical experiments indicates that the mW description of ice I-h is excessively ductile. One possible contribution to this enhanced malleability is the absence of explicit protons in the mW model, disregarding the fundamental asymmetry of the hydrogen bond that plays an important role in the nucleation and motion of lattice dislocations in ice I-h. Published by AIP Publishing.

Assessment of the kidney and lung as immune barriers and hematopoietic sites in the invasive apple snail Pomacea canaliculata

Rodriguez, C ;Prieto, GI ; Vega, IA ; Castro-Vazquez, A ; PEERJ ,2018 ,6 ,-.

Knowledge on the immune system of Pomacea canaliculata is becoming increasingly important, because of this gastropod's role as intermediate host and vector of Angiostrongylus cantonensis, the etiologic agent of eosinophilic meningitis in humans and domestic animals. Immune defenses of this gastropod comprise both humoral and cellular components, but they may also involve organs that act as immune barriers to prevent the spread of alien molecules and organisms. Both the kidney and lung are here shown to serve this function, because of (1) their positions in blood circulation, (2) the intricate architecture of their blood spaces, and (3) the proliferative and nodulation reactions of hemocytes to an immune challenge. However, these organs differ in that only the kidney shows permanent hemocyte aggregations. Microcirculation in the kidney was found to flow through an intricate vascular bed containing the permanent aggregations, which occurred either as hemocyte islets anchored by cytoplasmic projections of the renal epithelium or as perivascular accretions. Within 96 h of the injection of yeast cells, hemocyte nodules were formed both in the kidney and lung. Moreover, cell proliferation in renal hemocyte islets was measured by bromodeoxyuridine (BrdU) incorporation. The proportion of BrdU positive nuclei increased 48 h after injection. Signs of nodule regression (apoptotic bodies, lipofuscin-like deposits) and a decrease in the proportion of BrdU positive nuclei were found at 96 h. In addition, the area of renal hemocyte islets was significantly increased 96 h after injection. Nevertheless, the high complexity of the small vascular chambers that constitute the lung's respiratory lamina would also facilitate hemocyte-antigen contacts, required to elicit cellular aggregation, and hence, nodulation. To our knowledge, this paper includes the first quantitative indication of hemocyte proliferation after an immune challenge among Caenogastropoda.

Phenology determines the robustness of plant-pollinator networks

Ramos-Jiliberto, R ;de Espanes, PM ; Franco-Cisterna, M ; Petanidou, T ; Vazquez, DP ; SCIENTIFIC REPORTS ,2018 ,8 ,-.

Plant-pollinator systems are essential for ecosystem functioning, which calls for an understanding of the determinants of their robustness to environmental threats. Previous studies considering such robustness have focused mostly on species' connectivity properties, particularly their degree. We hypothesized that species' phenological attributes are at least as important as degree as determinants of network robustness. To test this, we combined dynamic modeling, computer simulation and analysis of data from 12 plant-pollinator networks with detailed information of topology of interactions as well as species' phenology of plant flowering and pollinator emergence. We found that phenological attributes are strong determinants of network robustness, a result consistent across the networks studied. Plant species persistence was most sensitive to increased larval mortality of pollinators that start earlier or finish later in the season. Pollinator persistence was especially sensitive to decreased visitation rates and increased larval mortality of specialists. Our findings suggest that seasonality of climatic events and anthropic impacts such as the release of pollutants is critical for the future integrity of terrestrial biodiversity.

Chemical taphonomy and preservation modes of Jurassic spinicaudatans from Patagonia: a chemometric approach

Monferran, MD ;D'Angelo, JA ; Cabaleri, NG ; Gallego, OF ; Garban, G ; JOURNAL OF PALEONTOLOGY ,2018 ,92 ,1054 -1065 .

Spinicaudatans ('clam shrimps') are small branchiopod crustaceans enclosed in a chitinous bivalved carapace that is often the only preserved element in the fossil record. However, few studies have analyzed the preservation of these carapaces, which have been found in continental facies from the Devonian to the present. The aim of this study was to contribute to a better understanding of the chemical preservation of fossil spinicaudatan carapaces, and it focused on spinicaudatan carapaces of the Cariadon Asfalto Formation from the Jurassic of Argentina. Semiquantitative energy-dispersive X-ray spectrometry (EDS) analysis provided elemental composition data that were interpreted using principal component analysis (PCA). The results showed a complex chemical mode of preservation for spinicaudatan carapaces. In some parts, EDS spectra of the specimens exhibit peaks of calcium, phosphorous, aluminum, and fluorine, representing the retention of original carapace material with some diagenetic recrystallization. Certain zones of the carapace show low-intensity peaks of the elements mentioned, while silicon and oxygen peaks (from the rock matrix) become the dominant spectral signals. These modes of preservation modify the interpretations and observations of the ornamentation of the carapace, which are used as taxonomic features. Our results suggest that specific diagenetic processes play a fundamental role in the preservation of spinicaudatans.

Chronic Infections: A Possible Scenario for Autophagy and Senescence Cross-Talk

Aguilera, MO ;Delgui, LR ; Romano, PS ; Colombo, MI ; CELLS ,2018 ,7 ,-.

Multiple tissues and systems in the organism undergo modifications during aging due to an accumulation of damaged proteins, lipids, and genetic material. To counteract this process, the cells are equipped with specific mechanisms, such as autophagy and senescence. Particularly, the immune system undergoes a process called immunosenescence, giving rise to a chronic inflammatory status of the organism, with a decreased ability to counteract antigens. The obvious result of this process is a reduced defence capacity. Currently, there is evidence that some pathogens are able to accelerate the immunosenescence process for their own benefit. Although to date numerous reports show the autophagy-senescence relationship, or the connection between pathogens with autophagy or senescence, the link between the three actors remains unexplored. In this review, we have summarized current knowledge about important issues related to aging, senescence, and autophagy.

Density and biomechanical properties of fossil fronds. A case study of Neuropteris ovata (seed fern, Late Pennsylvanian, Canada)

D'Angelo, JA ;Zodrow, EL ; INTERNATIONAL JOURNAL OF COAL GEOLOGY ,2018 ,198 ,63 -76 .

A theoretical biomechanical model is proposed for the largest known 650 mm-long frond segment Neuropteris ovata var. simonii (Medullosales, Pennsylvanian, Sydney Coalfield, Canada). The study procedure includes, amongst others, a novel methodology for calculating density of fossil pinnules and rachides. This, in conjunction with the trait relationships and mathematical models that linked density and material/structural properties established for modern plant-leaf tissues, permits the estimation of tensile strength, tensile modulus of elasticity, flexural stiffness, and leaf mass per area. Results suggest that, theoretically, (a) the living frond invested a considerable amount of resources for the construction of metabolically expensive, hard, tough, and resistant pinnule and rachial tissues, which were "made to last", and (b) were used as part of a combination of strategies that increased the plant's biomechanical stability. This translated in resistance to damage during the application of external loads such as those exerted by strong winds or tropical storms. High leaf mass per area (dry-mass investment) of pinnules and rachial tissues points to a slow photosynthetic return that was sustained for long periods of time (long leaf lifespan). The latter possibly indicates a plant adaptation to wet, levee-top habitats, which were characterized by nutrient-deficient soils exposed to intensive solar irradiation. The 3D, chemistry based model of the N. ovata specimen provided new insights into the hitherto poorly-known biomechanical and related traits of this iconic medullosalean plant that inhabited Pennsylvanian wetlands. Other implications of using our chemistry-based methodology include the estimation of (i) frond size and shape (plant reconstructions), (ii) plant ecophysiological adaptations to different wetland environments, and (iii) plant phylogenetic and ontogenetic adaptations.

Hypoxia-ischemia alters distribution of lysosomal proteins in rat cortex and hippocampus

Troncoso, M ;Bannoud, N ; Carvelli, L ; Asensio, J ; Seltzer, A ; Sosa, MA ; BIOLOGY OPEN ,2018 ,7 ,-.

Neuronal excitotoxicity induced by glutamatergic receptor overstimulation contributes to brain damage. Recent studies have shown that lysosomal membrane permeabilization (LMP) is involved in ischemia-associated neuronal death. In this study we evaluated the effect of neonatal hypoxia-ischemia (HI), as a model of excitotoxicity, on the lysosomal integrity throughout the distribution of the lysosomal proteins cathepsin D and prosaposin. Rat pups (7 days old) of the Wistar Kyoto strain were submitted to HI and they were euthanized 4 days after treatment and the cerebral cortex (Cx) and hippocampus (HIP) were processed for immunohistochemistry or immunoblotting. Treatment induced an increase of gliosis and also a redistribution of both prosaposin and cathepsin D (as intermediate and mature forms), into the cytosol of the HIP and Cx. In addition, HI induced a decrease of LAMP-1 in the membranous fraction and the appearance of a reactive band to anti-LAMP-1 in the cytosolic fraction, suggesting a cleavage of this protein. From these results, we propose that the abnormal release of Cat D and PSAP to the cytosol is triggered as a result of LAMP-1 cleavage in HI animals, which leads to cell damage. This could be a common mechanism in pathological conditions that compromises neuronal survival and brain function.

Tolerance to hypometabolism and arousal induced by hibernation in the apple snail Pomacea canaliculata (Caenogastropoda, Ampullariidae)

Giraud-Billoud, M ;Castro-Vazquez, A ; Campoy-Diaz, AD ; Giuffrida, PM ; Vega, IA ; COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY B-BIOCHEMISTRY & MOLECULAR ,2018 ,224 ,129 -137 .

Pomacea canaliculata may serve as a model organism for comparative studies of oxidative damage and antioxidant defenses in active, hibernating and arousing snails. Oxidative damage (as TBARS), free radical scavenging capacity (as ABTS(+) oxidation), uric acid (UA) and glutathione (GSH) concentrations, activities of superoxide dismutase (SOD) and catalase (CAT), and the protein expression levels of heat shock proteins (Hsp70, Hsc70, Hsp90) were studied in digestive gland, kidney and foot. Tissue TBARS of hibernating snails (45 days) was higher than active snails. Hibernation produced an increase of ABTS(+) in digestive gland, probably because of the sustained antioxidant defenses (UA and/or GSH and SOD levels). Kidney protection during the activity hibernation cycle seemed provided by increased UA concentrations. TSARS in the foot remained high 30 min after arousal with no changes in ABTS, but this tissue increased ABTS oxidation at 24 h to expenses increased UA and decreased GSH levels, and with no changes in SOD and CAT activities. The level of Hsp70 in kidney showed no changes throughout the activity-hibernation cycle but it increased in the foot after hibernation. The tissue levels of Hsp90 in snails hibernating were higher than active snails and returned to baseline 24 h after arousal. Results showed that chronic cooling produces a significant oxidative damage in three studied tissues and that these tissue damages are overcome quickly (between 30 min to 24 h) with fluctuations in different antioxidant defenses (UA, GSH, CAT) and heat shock proteins (Hsp70 and Hsp90).

Self-organizing dynamical networks able to learn autonomously

Kaluza, P ;EPL ,2018 ,123 ,-.

We present a model for the time evolution of network architectures based on dynamical systems. We show that the evolution of the existence of a connection in a network can be described as a stochastic non-Markovian telegraphic signal (NMTS). Such signal is formulated in two ways: as an algorithm and as the result of a system of differential equations. The autonomous learning conjecture (Kaluza P. and Mikhailov A.S., Phys. Rev. E, 90 (2014) 030901(R)) is implemented in the proposed dynamics. As a result, we construct self-organizing dynamical systems (networks) able to modify their structures in order to learn prescribed target functionalities. This theory is applied to two systems: the flow processing networks with time-programmed responses, and a system of first-order chemical reactions. In both cases, we show examples of the evolution and a statistical analysis of the obtained functional networks with respect to the model parameters. Copyright (C) EPLA, 2018

Osteology of the Late Cretaceous Argentinean sauropod dinosaur Mendozasaurus neguyelap: implications for basal titanosaur relationships

Riga, BJG ;Mannion, PD ; Poropat, SF ; David, LDO ; Coria, JP ; ZOOLOGICAL JOURNAL OF THE LINNEAN SOCIETY ,2018 ,184 ,136 -181 .

The titanosaurian sauropod dinosaur Mendozasaurus neguyelap is represented by several partial skeletons from a single locality within the Coniacian (lower Upper Cretaceous) Sierra Barrosa Formation in the south of Mendoza Province, northern Neuquen Basin, Argentina. A detailed revision of Mendozasaurus, including previously undocumented remains from the holotype site, allows us to more firmly establish its position within Titanosauria, as well as enabling an emended diagnosis of this taxon. Autapomorphies include: (1) middle and posterior cervical vertebrae with tall and transversely expanded neural spines that are wider than the centra, formed laterally by spinodiapophy-seal laminae that are not connected with the pre- or postzygapophyses; (2) anterior caudal vertebrae (excluding anterior-most) with ventrolateral ridge-like expansion of prezygapophyses; and (3) humerus with divided lateral distal condyle on anterior surface. New remains demonstrate that the presacral vertebrae of Mendozasaurus were not unusually short anteroposteriorly, with this compression instead resulting from taphonomic crushing. Comparative studies of articulated pedes of other taxa allow us to interpret that the pedal formula of Mendozasaurus was 2-2-2-2-0, based on disarticulated bones that form a right hind foot. Mendozasaurus was incorporated into an expanded version of a titanosauriform-focussed phylogenetic data matrix, along with several other contemporaneous South American titanosaurs. The resultant data matrix comprises 84 taxa scored for 423 characters, and our phylogenetic analysis recovers Mendozasaurus as the most basal member of a diverse Lognkosauria, including Futalognkosaurus and the gigantic titanosaurs Argentinosaurus, Notocolossus, Patagotitan and Puertasaurus. Lognkosauria forms a clade with Rinconsauria (Muyelensaurus + Rinconsaurus), with Epachthosaurus and Pitekunsaurus recovered at the base of this grouping. A basal lithostrotian position for this South American clade is well supported, contrasting with some analyses that have placed these taxa outside of Lithostrotia or closer to Saltasauridae. The sister clade to this South American group is composed of an array of near-global taxa and supports the hypothesis that most titanosaurian clades were widespread by the Early-middle Cretaceous.

Epigenetic regulation of ID4 in breast cancer: tumor suppressor or oncogene?

Nasif, D ;Campoy, E ; Laurito, S ; Branham, R ; Urrutia, G ; Roque, M ; Branham, MT ; CLINICAL EPIGENETICS ,2018 ,10 ,-.

Background: Inhibitor of differentiation protein 4 (ID4) is a dominant negative regulator of the basic helix-loophelix (bHLH) family of transcription factors. During tumorigenesis, ID4 may act as a tumor suppressor or as an oncogene in different tumor types. However, the role of ID4 in breast cancer is not clear where both an oncogenic and a tumor suppressor function have been attributed. Here, we hypothesize that ID4 behaves as both, but its role in breast differs according to the estrogen receptor (ER) status of the tumor.

Elucidating mysteries of phase-segregated membranes: mobile-lipid recruitment facilitates pores' passage to the fluid phase

Marti, JML ;English, NJ ; Del Popolo, MG ; PHYSICAL CHEMISTRY CHEMICAL PHYSICS ,2018 ,20 ,19234 -19239 .

Phase segregation of multicomponent lipid bilayers leads to, under phase-coexistence conditions, domain formation, featuring delimitation by essentially one-dimensional borders. (Micro-)phase segregation of bilayers is proposed to influence the physiological behaviour of cell membranes and provides the driving force for lipid-raft formation. Experiments show a maximum in the electrical-conductivity of membranes at the phase-transition point, which has been conjectured to arise from border-nucleated transmembrane-conducting defects or pores. However, recent electroporation experiments on phase-segregated bilayers demonstrate electro-pore detection in the liquid disordered phase (L-d), wherein they diffuse over macroscopic periods without absorption into the liquid ordered phase (L-o). Here, we scrutinise transmembrane-pore formation via molecular dynamics simulations on a multicomponent phase-segregated bilayer. We find that pores created in L-o domains always migrate spontaneously to the L-d phase, via recruitment' of unsaturated lipids to the pore's rim to transport the pore to the fluid phase under a large stress-field driving force. Once in L-d domains, pores migrate towards their centre, never returning or pinning to L-o. These findings are explained by thermodynamics. By comparing the free-energy cost for creating pores in the bulk of L-d and L-o membranes, and in the phase-segregated system, we show that it is always more energetically tractable to create pores in L-d domains, independent of the pore size.

Weighted Symbolic Dependence Metric (wSDM) for fMRI resting-state connectivity: A multicentric validation for frontotemporal dementia

Moguilner, S ;Garcia, AM ; Mikulan, E ; Hesse, E ; Garcia-Cordero, I ; Melloni, M ; Cervetto, S ; Serrano, C ; Herrera, E ; Reyes, P ; Matallana, D ; Manes, F ; Ibanez, A ; Sedeno, L ; SCIENTIFIC REPORTS ,2018 ,8 ,-.

The search for biomarkers of neurodegenerative diseases via fMRI functional connectivity (FC) research has yielded inconsistent results. Yet, most FC studies are blind to non-linear brain dynamics. To circumvent this limitation, we developed a "weighted Symbolic Dependence Metric" (wSDM) measure. Using symbolic transforms, we factor in local and global temporal features of the BOLD signal to weigh a robust copula-based dependence measure by symbolic similarity, capturing both linear and non-linear associations. We compared this measure with a linear connectivity metric (Pearson's R) in its capacity to identify patients with behavioral variant frontotemporal dementia (bvFTD) and controls based on resting-state data. We recruited participants from two international centers with different MRI recordings to assess the consistency of our measure across heterogeneous conditions. First, a seed-analysis comparison of the salience network (a specific target of bvFTD) and the default-mode network (as a complementary control) between patients and controls showed that wSDM yields better identification of resting-state networks. Moreover, machine learning analysis revealed that wSDM yielded higher classification accuracy. These results were consistent across centers, highlighting their robustness despite heterogeneous conditions. Our findings underscore the potential of wSDM to assess fMRI-derived FC data, and to identify sensitive biomarkers in bvFTD.


Diaz, MAL ;D'Angelo, JA ; Del Fueyo, GM ; Zodrow, EL ; PALAIOS ,2018 ,33 ,323 -337 .

The present study is a holistic approach to the relationship between volcaniclastic host rock characteristics and the fossilization processes of short leafy coniferous branches of Squamastrobus tigrensis, preserved as fossilized-cuticles (Lower Cretaceous, Baquero Group, Patagonia, Argentina). The question of diagenetic influences of Aptian volcaniclastic sedimentation on preservation chemistry and taphonomic processes is addressed. Whereas infrared spectroscopy provided chemical information on the leaves, vitrinite reflectance and complementary thermal indicators provided data on the thermal maturity of the dispersed organic matter in the host rock. Three sample types were analyzed: fossilized-cuticle, macerated fossilized-cuticle (by infrared spectroscopy), and associated organic host rock matter (by light microscopy). Results clearly show chemical variability between, and within the fossilized-cuticle and cuticle, as well as a similarity to type I/II kerogen, i.e., high contents of both aliphatic groups and oxygen-containing compounds. Combined with the lower maturity of the host rock, the importance of the depositional environment during burial and taphonomic conditions that affected the fossilization of S. tigrensis arc summarized in a general fossilization model.

Meta-heuristic based autoscaling of cloud-based parameter sweep experiments with unreliable virtual machines instances

Monge, DA ;Pacini, E ; Mateos, C ; Garino, CG ; COMPUTERS & ELECTRICAL ENGINEERING ,2018 ,69 ,364 -377 .

Cloud Computing is the delivery of on-demand computing resources over the Internet on a pay-per-use basis and is very useful to execute scientific experiments such as parameter sweep experiments (PSEs). When PSEs are executed it is important to reduce both the makespan and monetary cost. We propose a novel tri-objective formulation for the PSEs autoscaling problem considering unreliable virtual machines (VM) pursuing the minimization of makespan, monetary cost and probability of failures. We also propose a new autoscaler based on the Non-dominated Sorting Genetic Algorithm II able to automatically determine the right amount for each type of VM and pricing scheme, as well as the bid prices for the spot instances. Experiments show that the proposed autoscaler achieves great improvements in terms of makespan and cost when it is compared against Scaling First and Spot Instances Aware Autoscaling. (C) 2017 Elsevier Ltd. All rights reserved.

Magnetic ionic liquid-based dispersive liquid-liquid microextraction technique for preconcentration and ultra-trace determination of Cd in honey

Fiorentini, EF ;Escudero, LB ; Wuilloud, RG ; ANALYTICAL AND BIOANALYTICAL CHEMISTRY ,2018 ,410 ,4715 -4723 .

A simple, highly efficient, batch, and centrifuge-less dispersive liquid-liquid microextraction method based on a magnetic ionic liquid (MIL-DLLME) and electrothermal atomic absorption spectrometry (ETAAS) detection was developed for ultra-trace Cd determination in honey. Initially, Cd(II) was chelated with ammonium diethyldithiophosphate (DDTP) at pH 0.5 followed by its extraction with the MIL trihexyl(tetradecyl)phosphonium tetrachloroferrate(III) ([P-6,P-6,P-6,P-14]FeCl4) and acetonitrile as dispersant. The MIL phase containing the analyte was separated from the aqueous phase using only a magnet. A back-extraction procedure was applied to recover Cd from the MIL phase using diluted HNO3 and this solution was directly injected into the graphite furnace of ETAAS instrument. An extraction efficiency of 93% and a sensitivity enhancement factor of 112 were obtained under optimal experimental conditions. The detection limit (LOD) was 0.4 ng L-1 Cd, while the relative standard deviation (RSD) was 3.8% (at 2 mu g L-1 Cd and n = 10), calculated from the peak height of absorbance signals. This work reports the first application of the MIL [P-6,P-6,P-6,P-14]FeCl4 along with the DLLME technique for the successful determination of Cd at trace levels in different honey samples.

Effects of common cooking heat treatments on selenium content and speciation in garlic

Perez, MB ;Maniero, MA ; Londonio, A ; Smichowski, P ; Wuilloud, RG ; JOURNAL OF FOOD COMPOSITION AND ANALYSIS ,2018 ,70 ,54 -62 .

The effect of traditional thermal treatments, normally applied during cooking practices, on the stability of Se amino acids and Se-proteins present in Se-enriched garlic was studied. Five heat treatments including, convection oven (180 degrees C, 10 min), boiling (100 degrees C, 10 min), microwave oven (800 W, 3 min), steaming (10 min) and stir-frying (180 degrees C, 3 min) were assayed. Modifications on the molecular weight fractions profiles of protein extracts were evaluated by size exclusion chromatography with UV-visible and inductively coupled plasma mass spectrometry (ICP-MS) detection using a 0.05 M Tris(hidroxymethyl)aminomethane solution at pH 7.3 as the mobile phase. Possible modifications of Se-amino acids were evaluated by anion exchange chromatography (AEC), with a 30 mM Na2HPO4 solution (pH 6) as the mobile phase, coupled to ICP-MS after enzymatic hydrolysis. SEC chromatograms showed the incorporation of Se to high (7 kDa) and low molecular weight fractions (2-4 kDa) while AEC chromatograms showed mostly the presence of Se-methylselenocysteine. However, it could be observed that heat treatments significantly affect this important Se-amino acid.

Poset splitting and minimality of finite models

Cianci, N ;Ottina, M ; JOURNAL OF COMBINATORIAL THEORY SERIES A ,2018 ,157 ,120 -161 .

We prove that the fundamental group and the integral homology groups of a poset with fewer than 13 points are torsion free, settling a conjecture of Hardie, Vermeulen and Witbooi and answering a question of Barmak. In addition, we prove that if a poset has fewer than 16 points then the geometric realization of its order complex can not be homotopy equivalent to either the torus or the Klein bottle, answering another open question. Furthermore, we find all the posets of 16 points (resp. of 13 points) such that the geometric realizations of their order complexes are homotopy equivalent to either the torus or the Klein bottle (resp. to the real projective plane). (C) 2018 Elsevier Inc. All rights reserved.

Growth of Ni nanoclusters on irradiated graphene: a molecular dynamics study

Valencia, FJ ;Hernandez-Vazquez, EE ; Bringa, EM ; Moran-Lopez, JL ; Rogan, J ; Gonzalez, RI ; Munoz, F ; PHYSICAL CHEMISTRY CHEMICAL PHYSICS ,2018 ,20 ,16347 -16353 .

We studied the soft landing of Ni atoms on a previously damaged graphene sheet by means of molecular dynamics simulations. We found a monotonic decrease of the cluster frequency as a function of its size, but few big clusters comprise an appreciable fraction of the total number of Ni atoms. The aggregation of Ni atoms is also modeled by means of a simple phenomenological model. The results are in clear contrast with the case of hard or energetic landing of metal atoms, where there is a tendency to form mono-disperse metal clusters. This behavior is attributed to the high diffusion of unattached Ni atoms, together with vacancies acting as capture centers. The findings of this work show that a simple study of the energetics of the system is not enough in the soft landing regime, where it is unavoidable to also consider the growth process of metal clusters.

Glycosylation-dependent galectin-receptor interactions promote Chlamydia trachomatis infection

Lujan, AL ;Croci, DO ; Tudelaa, JAG ; Losinno, AD ; Cagnoni, AJ ; Marino, KV ; Damiani, MT ; Rabinovich, GA ; PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF ,2018 ,115 ,E6000 -E6009 .

Chlamydia trachomatis (Ct) constitutes the most prevalent sexually transmitted bacterium worldwide. Chlamydial infections can lead to severe clinical sequelae including pelvic inflammatory disease, ectopic pregnancy, and tuba! infertility. As an obligate intracellular pathogen, Ct has evolved multiple strategies to promote adhesion and invasion of host cells, including those involving both bacterial and host glycans. Here, we show that galectin-1 (Gall), an endogenous lectin widely expressed in female and male genital tracts, promotes Ct infection. Through glycosylation-dependent mechanisms involving recognition of bacterial glycoproteins and N-glycosylated host cell receptors, Gall enhanced Ct attachment to cervical epithelial cells. Exposure to Gall, mainly in its dimeric form, facilitated bacterial entry and increased the number of infected cells by favoring Ct-Ct and Ct-host cell interactions. These effects were substantiated in vivo in mice lacking Gall or complex 01-6-branched Nglycans. Thus, disrupting Gall-N-glycan interactions may limit the severity of chlamydial infection by inhibiting bacterial invasion of host cells.

Using Intrinsic Surfaces To Calculate the Free-Energy Change When Nanoparticles Adsorb on Membranes

Klug, J ;Triguero, C ; Del Popolo, MG ; Tribello, GA ; JOURNAL OF PHYSICAL CHEMISTRY B ,2018 ,122 ,6417 -6422 .

A reaction coordinate that can be used when investigating binding to dynamical surfaces with molecular dynamics is introduced. This coordinate measures the distance between the adsorbate and an isocontour in a density field. Furthermore, the coordinate is continuous so simulation biases that are a function of this coordinate can be added to the Hamiltonian to increase the rate of adsorption/desorption. The efficacy of this new coordinates is demonstrated by performing metadynamics simulations to measure the strength with which a hydrophilic nanoparticle binds to a lipid bilayer. An investigation of the binding mechanism that is performed using the coordinate demonstrates that the lipid bilayer undergoes a series of concerted changes in structure as the nanoparticle binds.

Orographic and convective gravity waves above the Alps and Andes Mountains during GPS radio occultation events - a case study

Hierro, R ;Steiner, AK ; de la Torre, A ; Alexander, P ; Llamedo, P ; Cremades, P ; ATMOSPHERIC MEASUREMENT TECHNIQUES ,2018 ,11 ,3523 -3539 .

Gravity waves (GWs) and convective systems play a fundamental role in atmospheric circulation, weather, and climate. Two usual main sources of GWs are orographic effects triggering mountain waves and convective activity. In addition, GW generation by fronts and geostrophic adjustment must also be considered. The utility of Global Positioning System (GPS) radio occultation (RO) observations for the detection of convective systems is tested. A collocation database between RO events and convective systems over subtropical to midlatitude mountain regions close to the Alps and Andes is built. From the observation of large-amplitude GW structures in the absence of jets and fronts, subsets of RO profiles are sampled. A representative case study among those considered at each region is selected and analyzed. The case studies are investigated using mesoscale Weather Research and Forecasting (WRF) simulations, ERA-Interim reanalysis data, and measured RO temperature profiles. The absence of fronts or jets during both case studies reveals similar relevant GW features (main parameters, generation, and propagation). Orographic and convective activity generates the observed GWs. Mountain waves above the Alps reach higher altitudes than close to the Andes. In the Andes case, a critical layer prevents the propagation of GW packets up to stratospheric heights. The case studies are selected also because they illustrate how the observational window for GW observations through RO profiles admits a misleading interpretation of structures at different altitude ranges. From recent results, the distortion introduced in the measured atmospheric vertical wavelengths by one of the RO events is discussed as an illustration. In the analysis, both the elevation angle of the sounding path (line of tangent points) and the gravity wave aspect ratio estimated from the simulations and the line of sight are taken into account. In both case studies, a considerable distortion, over- and underestimation of the vertical wavelengths measured by RO, may be expected.

Nanoindentation tests of heavy-ion-irradiated Au foams-molecular dynamics simulation

Ruestes, CJ ;Anders, C ; Bringa, EM ; Urbassek, HM ; JOURNAL OF APPLIED PHYSICS ,2018 ,123 ,-.

Irradiation by light ions may change the mechanical properties of nanofoams. Using molecular-dynamics simulation, we study the effect of irradiating a Au foam (porosity, 50%, and ligament diameter, 3 nm) with heavy ions: here, 10 keV Au ions up to a dose of 4 x 10(16) m(-2). We demonstrate that in consequence, the ligament morphology changes in the irradiated region, caused by local melting. The changes in mechanical properties are monitored by simulated nanoindentation tests. We find that the foam hardness is only around 1/3 of the hardness of a bulk Au crystal. Irradiation increases the hardness of the foam by around 10% in the central irradiated area. The plastic zone extends to only 1.5 a(c), where a(c) denotes the contact radius; this value is unchanged under irradiation. The hardness increase after irradiation is attributed to two concurring effects. To begin with, irradiation induces melting and annealing of the ligaments, leading to their coarsening and alleviating surface stress, which in turn increases the dislocation nucleation threshold. In addition, irradiation introduces a stacking fault forest that acts as an obstacle to dislocation motion. Published by AIP Publishing.

Infectious Bursal Disease Virus Hijacks Endosomal Membranes as the Scaffolding Structure for Viral Replication

Gimenez, MC ;Zanetti, FA ; Terebiznik, MR ; Colombo, MI ; Delgui, LR ; JOURNAL OF VIROLOGY ,2018 ,92 ,-.

Birnaviruses are unconventional members of the group of double-stranded RNA (dsRNA) viruses that are characterized by the lack of a transcriptionally active inner core. Instead, the birnaviral particles organize their genome in ribonucleoprotein complexes (RNPs) composed by dsRNA segments, the dsRNA-binding VP3 protein, and the virally encoded RNA-dependent RNA polymerase (RdRp). This and other structural features suggest that birnaviruses may follow a completely different replication program from that followed by members of the Reoviridae family, supporting the hypothesis that birnaviruses are the evolutionary link between single-stranded positive RNA (+ssRNA) and dsRNA viruses. Here we demonstrate that infectious bursal disease virus (IBDV), a prototypical member of the Birnaviridae family, hijacks endosomal membranes of infected cells through the interaction of a viral protein, VP3, with the phospholipids on the cytosolic leaflet of these compartments for replication. Employing a mutagenesis approach, we demonstrated that VP3 domain PATCH 2 (P2) mediates the association of VP3 with the endosomal membranes. To determine the role of VP3 P2 in the context of the virus replication cycle, we used avian cells stably overexpressing VP3 P2 for IBDV infection. Importantly, the intra- and extracellular virus yields, as well as the intracellular levels of VP2 viral capsid protein, were significantly diminished in cells stably overexpressing VP3 P2. Together, our results indicate that the association of VP3 with endosomes has a relevant role in the IBDV replication cycle. This report provides direct experimental evidence for membranous compartments such as endosomes being required by a dsRNA virus for its replication. The results also support the previously proposed role of birnaviruses as an evolutionary link between +ssRNA and dsRNA viruses. IMPORTANCE Infectious bursal disease (IBD; also called Gumboro disease) is an acute, highly contagious immunosuppressive disease that affects young chickens and spreads worldwide. The etiological agent of IBD is infectious bursal disease virus (IBDV). This virus destroys the central immune organ (bursa of Fabricius), resulting in immunosuppression and reduced responses of chickens to vaccines, which increase their susceptibility to other pathogens. IBDV is a member of Birnaviridae family, which comprises unconventional members of dsRNA viruses, whose replication strategy has been scarcely studied. In this report we show that IBDV hijacks the endosomes of the infected cells for establishing viral replication complexes via the association of the ribonucleoprotein complex component VP3 with the phospholipids in the cytosolic leaflet of endosomal membranes. We show that this interaction is mediated by the VP3 PATCH 2 domain and demonstrate its relevant role in the context of viral infection.


Marsh, EJ ;Bruno, MC ; Fritz, SC ; Baker, P ; Capriles, JM ; Hastorf, CA ; RADIOCARBON ,2018 ,60 ,925 -940 .

Because the C-14 calibration curves IntCal and SHCal are based on data from temperate latitudes, it remains unclear which curve is more suitable for archaeological and paleoenvironmental records from tropical South America. A review of climate dynamics reveals a significant influx of Northern Hemisphere air masses and moisture over a substantial part of the continent during the South American Summer Monsoon (SASM). Areas affected by the SASM receive unknown amounts of input from both hemispheres, where an argument could be made for either curve. Until localized tree-ring data can resolve this, we suggest using a mixed calibration curve, which accounts for inputs from both hemispheres, as a third calibration option. We present a calibration example from a crucial period of environmental and cultural change in the southern Lake Titicaca. Given our current lack of data on past C-14 variation in South America, our calibrations and chronologies will likely change in the future. We hope this paper spurs new research into this topic and encourages researchers to make an informed and explicit choice of which curve to use, which is particularly relevant in research on past human-environmental relationships.

Towards a comprehensive picture of C-to-U RNA editing sites in angiosperm mitochondria

Edera, AA ;Gandini, CL ; Sanchez-Puerta, MV ; PLANT MOLECULAR BIOLOGY ,2018 ,97 ,215 -231 .

Our understanding of the dynamic and evolution of RNA editing in angiosperms is in part limited by the few editing sites identified to date. This study identified 10,217 editing sites from 17 diverse angiosperms. Our analyses confirmed the universality of certain features of RNA editing, and offer new evidence behind the loss of editing sites in angiosperms.

Species traits and network structure predict the success and impacts of pollinator invasions

Valdovinos, FS ;Berlow, EL ; de Espanes, PM ; Ramos-Jiliberto, R ; Vazquez, DP ; Martinez, ND ; NATURE COMMUNICATIONS ,2018 ,9 ,-.

Species invasions constitute a major and poorly understood threat to plant-pollinator systems. General theory predicting which factors drive species invasion success and subsequent effects on native ecosystems is particularly lacking. We address this problem using a consumer-resource model of adaptive behavior and population dynamics to evaluate the invasion success of alien pollinators into plant-pollinator networks and their impact on native species. We introduce pollinator species with different foraging traits into network models with different levels of species richness, connectance, and nestedness. Among 31 factors tested, including network and alien properties, we find that aliens with high foraging efficiency are the most successful invaders. Networks exhibiting high alien-native diet overlap, fraction of alien-visited plant species, most-generalist plant connectivity, and number of specialist pollinator species are the most impacted by invaders. Our results mimic several disparate observations conducted in the field and potentially elucidate the mechanisms responsible for their variability.

Stratospheric Injection of Brominated Very Short-Lived Substances: Aircraft Observations in the Western Pacific and Representation in Global Models

Wales, PA ;Salawitch, RJ ; Nicely, JM ; Anderson, DC ; Canty, TP ; Baidar, S ; Dix, B ; Koenig, TK ; Volkamer, R ; Chen, DX ; Huey, LG ; Tanner, DJ ; Cuevas, CA ; Fernandez, RP ; Kinnison, DE ; Lamarque, JF ; Saiz-Lopez, A ; Atlas, EL ; Hall, SR ; Navarro, MA ; Pan, LL ; Schauffler, SM ; Stell, M ; Tilmes, S ; Ullmann, K ; Weinheimer, AJ ; Akiyoshi, H ; Chipperfield, MP ; Deushi, M ; Dhomse, SS ; Feng, WH ; Graf, P ; Hossaini, R ; Jockel, P ; Mancini, E ; Michou, M ; Morgenstern, O ; Oman, LD ; Pitari, G ; Plummer, DA ; Revell, LE ; Rozanov, E ; Saint-Martin, D ; Schofield, R ; Stenke, A ; Stone, KA ; Visioni, D ; Yamashita, Y ; Zeng, G ; JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES ,2018 ,123 ,5690 -5719 .

We quantify the stratospheric injection of brominated very short-lived substances (VSLS) based on aircraft observations acquired in winter 2014 above the Tropical Western Pacific during the CONvective TRansport of Active Species in the Tropics (CONTRAST) and the Airborne Tropical TRopopause EXperiment (ATTREX) campaigns. The overall contribution of VSLS to stratospheric bromine was determined to be 5.02.1ppt, in agreement with the 53ppt estimate provided in the 2014 World Meteorological Organization (WMO) Ozone Assessment report (WMO 2014), but with lower uncertainty. Measurements of organic bromine compounds, including VSLS, were analyzed using CFC-11 as a reference stratospheric tracer. From this analysis, 2.90.6ppt of bromine enters the stratosphere via organic source gas injection of VSLS. This value is two times the mean bromine content of VSLS measured at the tropical tropopause, for regions outside of the Tropical Western Pacific, summarized in WMO 2014. A photochemical box model, constrained to CONTRAST observations, was used to estimate inorganic bromine from measurements of BrO collected by two instruments. The analysis indicates that 2.12.1ppt of bromine enters the stratosphere via inorganic product gas injection. We also examine the representation of brominated VSLS within 14 global models that participated in the Chemistry-Climate Model Initiative. The representation of stratospheric bromine in these models generally lies within the range of our empirical estimate. Models that include explicit representations of VSLS compare better with bromine observations in the lower stratosphere than models that utilize longer-lived chemicals as a surrogate for VSLS.

Dendrohydrology and water resources management in south-central Chile: lessons from the Rio Imperial streamflow reconstruction

Fernandez, A ;Munoz, A ; Gonzalez-Reyes, A ; Aguilera-Betti, I ; Toledo, I ; Puchi, P ; Sauchyn, D ; Crespo, S ; Frene, C ; Mundo, I ; Gonzalez, M ; Vignola, R ; HYDROLOGY AND EARTH SYSTEM SCIENCES ,2018 ,22 ,2921 -2935 .

Streamflow in south-central Chile (SCC, similar to 3742 degrees S) is vital for agriculture, forestry production, hydroelectricity, and human consumption. Recent drought episodes have generated hydrological deficits with damaging effects on these activities. This region is projected to undergo major reductions in water availability, concomitant with projected increases in water demand. However, the lack of long-term records hampers the development of accurate estimations of natural variability and trends. In order to provide more information on long-term streamflow variability and trends in SCC, here we report findings of an analysis of instrumental records and a tree-ring reconstruction of the summer streamflow of the Rio Imperial (similar to 37 degrees 40' S-38 degrees 50' S). This is the first reconstruction in Chile targeted at this season. Results from the instrumental streamflow record (similar to 1940 onwards) indicated that the hydrological regime is fundamentally pluvial with a small snowmelt contribution during spring, and evidenced a decreasing trend, both for the summer and the full annual record. The reconstruction showed that streamflow below the average characterized the post-1980 period, with more frequent, but not more intense, drought episodes. We additionally found that the recent positive phase of the Southern Annular Mode has significantly influenced streamflow. These findings agree with previous studies, suggesting a robust regional signal and a shift to a new hydrological scenario. In this paper, we also discuss implications of these results for water managers and stakeholders; we provide rationale and examples that support the need for the incorporation of tree-ring reconstructions into water resources management.

Land-use intensity indirectly affects ecosystem services mainly through plant functional identity in a temperate forest

Chillo, V ;Vazquez, DP ; Amoroso, MM ; Bennett, EM ; FUNCTIONAL ECOLOGY ,2018 ,32 ,1390 -1399 .

1. Land-use change is known to affect biodiversity, and there is increasing concern regarding how these changes may impact the provision of ecosystem services. Although functional composition (diversity and identity) could influence ecosystem properties and services at the community level, there is little quantitative understanding of these relationships in the field. Here, we evaluate the direct and indirect effects (through ecosystem properties) of biodiversity on the provision of multiple ecosystem services in native mixed forest in north-west Patagonia, and how land-use intensity influences these relationships.

The stability of hollow nanoparticles and the simulation temperature ramp

Reyes, PN ;Valencia, FJ ; Vega, H ; Ruestes, C ; Rogan, J ; Valdivia, JA ; Kiwi, M ; INORGANIC CHEMISTRY FRONTIERS ,2018 ,5 ,1139 -1144 .

Hollow nanoparticles (hNPs) are of interest because their large cavities and small thickness give rise to a large surface to volume ratio. However, in general they are not in equilibrium and far from their global energy minimum, which often makes them unstable against perturbations. In fact, a temperature increase can induce a structural collapse into a nanoparticle, and consequently a loss of their unique properties. This problem has been studied by means of molecular dynamics (MD) simulations, but without emphasis on the speed of the temperature increase. Here we explore how the temperature variation, and the rate at which it is varied in MD simulations, determines the final conformation of the hNPs. In particular, we show how different temperature ramps determine the final shape of Pt hNPs that initially have an external radius between 0.7 and 24 nm, and an internal radius between 0.19 and 2.4 nm. In addition, we also perform the simulations of other similar metals like Ag and Au. Our results indicate that the temperature ramp strongly modifies the final hNP shape, even at ambient temperature. In fact, a rapid temperature increase leads to the formation of stacking faults and twin boundaries which are not generated by a slower temperature increase. Quantitative criteria are established and they indicate that the stacking fault energy is the dominant parameter.

Usefulness of ionic liquids as mobile phase modifiers in HPLC-CV-AFS for mercury speciation analysis in food

Grijalba, AC ;Quintas, PY ; Fiorentini, EF ; Wuilloud, RG ; JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY ,2018 ,33 ,822 -834 .

Different ionic liquids (ILs) were studied in this work as mobile phase modifiers for the separation and determination of Hg2+, methylmercury (CH3Hg+) and ethylmercury (C2H5Hg+) species by reversed-phase high-performance liquid chromatography coupled to UV-cold vapor atomic fluorescence spectrometry (RP-HPLC-UV-CV-AFS). Several parameters influencing the chromatographic separation of Hg species, such as pH, sodium chloride concentration, organic solvent concentration, as well as chemical structure and concentration of ILs were evaluated. After a careful optimization, the separation of Hg species was achieved within 12 min using a C-18 column and a gradient developed by mixing methanol and a solution composed of 0.4% (v/v) 1-octyl-3-methylimidazolium chloride [C(8)mim]Cl, 100 mmol L-1 NaCl and 20 mmol L-1 buffer citric acid/citrate at pH 2.0. In addition, a multivariate methodology was applied to optimize the parameters involved in UV-CV-AFS detection of Hg species. The proposed method allowed the separation of inorganic and organic Hg species in a single chromatographic run. The limits of detection obtained for Hg species were in the range of 0.05-0.11 mu g L-1. The usefulness of the proposed method was demonstrated by performing Hg speciation analysis in highly complex samples, such as seafood, yeast and garlic, obtaining accurate and precise results in all cases.

Kinetic study of the dissolution of metakaolin with hydrofluoric acid

Pinna, EG ;Barbosa, LI ; Suarez, DS ; Rodriguez, MH ; INDIAN JOURNAL OF CHEMICAL TECHNOLOGY ,2018 ,25 ,287 -293 .

The kinetics mechanism on the dissolution of metakaolin by hydrofluoric acid has been studied. The effects of temperature, reaction time, and stirring speed have been examined. Experimental results show that reaction rate increases with both temperature and reaction time. The global process of metakaolin dissolution with HF is characterized with an apparent activation energy of 21.096 kcal/mol, which indicates that the reaction rate is mainly controlled by the chemical stage. Experimental data fitted the sequential nucleation and growth model.

Effect of salinity on locomotor performance and thermal extremes of metamorphic Andean Toads (Rhinella spinulosa) from Monte Desert, Argentina

Sanabria, E ;Quiroga, L ; Vergara, C ; Banchig, M ; Rodriguez, C ; Ontivero, E ; JOURNAL OF THERMAL BIOLOGY ,2018 ,74 ,195 -200 .

Rhinella spinulosa is distributed from Peru to Argentina (from 1200 to 5000 m elevation), inhabiting arid mountain valleys of the Andes, characterized by salty soils. The variations in soil salinity, caused by high evapotranspiration of water, can create an osmotic constraint and high thermal oscillations for metamorphsed Andean toad (R. spinulosa), affecting their thermoregulation and extreme thermal tolerances: We investigated the changes in thermal tolerance parameters (critical thermal maximum and crystallization temperature) of a population of metamorphosed R. spinulosa from the Monte Desert of San Juan, Argentina, under different substrate salinity conditions. Our results suggest that the locomotor performance of metamorphs of R. spinulosa is affected by increasing salinity concentrations in the environment where they develop. On the other hand, the thermal extremes of metamorphs of R. spinulosa also showed changes associated with different salinity conditions. According to other studies on different organisms, the increase of the osmolarity of the internal medium may increase the thermal tolerance of this species. More studies are needed to understand the thermo-osmolar adjustments of the metamorphs of toads to environmental variability.

Mechanical properties of Au foams under nanoindentation

Ruestes, CJ ;Schwen, D ; Millan, EN ; Aparicio, E ; Bringa, EM ; COMPUTATIONAL MATERIALS SCIENCE ,2018 ,147 ,154 -167 .

Nanoscale metallic foams display mechanical properties which make them attractive for a variety of technological applications. We report simulated nanoindentation tests for a model polycrystalline nanoporous gold structure with 11 nm mean filament diameter and 35 nm average grain size, comparable to foams produced by dealloying. Hardness, plasticity mechanisms, the extension of the plastic zone and the applicability of several scaling laws are discussed. Plasticity occurs at the nodes mainly and is dominated by nucleation of dislocations at the atomic steps of the ligament surfaces, in a dislocation accumulation scenario. Shockley partials, perfect dislocations, Hirth partials, Lomer-Cottrel locks and twins were identified. Grain boundary sliding appears to play a minor role in deformation at the indentation rates used. Several scaling laws are tested and their results and applicability are discussed based on the structural parameters of the foam and the deformation mechanisms identified. (C) 2018 Elsevier B.V. All rights reserved.

Human ranking of spaces and the role of caches: Case studies from Patagonia (Argentina)

Franco, NV ;Cortegoso, V ; Lucero, GF ; Duran, V ; QUATERNARY INTERNATIONAL ,2018 ,473 ,278 -289 .

Storage of artifacts is a common behavior among hunter-gatherers. Archaeologically, caches have been identified in different places and time periods. In this paper, we focus on the discussion of the role of caches recovered along the southern boundary of the Deseado Massif, Argentine Patagonia. Two caches, attributed to the colonization of this environment have been identified. Cache information is integrated into the known archaeological record of this space and spaces nearby and compared with data on raw material availability. In order to evaluate the location of the caches and understand human strategies of landscape utilization during this time period, we use GIS approaches along with available paleoenvironmental data. (C) 2017 Elsevier Ltd and INQUA. All rights reserved.

Toward Controlled Morphology of FeCu Nanoparticles: Cu Concentration and Size Effects

Rojas-Nunez, J ;Gonzalez, RI ; Bringa, EM ; Allende, S ; Sepulveda, P ; Arancibia-Miranda, N ; Baltazar, SE ; JOURNAL OF PHYSICAL CHEMISTRY C ,2018 ,122 ,8528 -8534 .

Bimetallic nanoparticles (NPs) can be tailored by varying the concentration of their constituent elements, resulting in novel structures and/or configurations, leading to interesting electronic, mechanical, and chemical properties. In this paper, by means of molecular dynamics calculations, we study the morphology of bimetallic FeCu NPs as a function of the Cu concentration. Our results evidence a core shell (CS) structure for low Cu concentrations and a Janus (JN)-like morphology for high Cu content. Structural and energy characterizations were performed to determine the atomic-scale behavior of the NPs. Using a continuous model to describe immiscible components, we obtain a stability transition curve between CS and JN-like structures for several NP sizes and concentrations. Results from both methods are compared with experimental data obtained for NPs with low and high Cu content, evidencing a good agreement among the three approaches.

Late Pleistocene and Holocene vegetation changes in the arid Andean piedmont of central Argentina inferred from sediment stable carbon isotopes and C/N ratios

Rojo, LD ;Mehl, AE ; Zarate, MA ; Garcia, A ; Chivas, AR ; PALAEOGEOGRAPHY PALAEOCLIMATOLOGY PALAEOECOLOGY ,2018 ,495 ,205 -213 .

Stable carbon isotopes (delta C-13) and C/N ratios in bulk sediment organic matter were used as indicators of C-3 and C-4 vegetation functional types in a ca. 40-kyr, predominantly alluvial sequence from Arroyo La Estacada (33.5 degrees S, 69 degrees W), in the arid Andean piedmont of central Argentina. Although this sediment sequence has the potential to contribute to the knowledge of past vegetation dynamics through its fossil pollen content, previous palynological studies provided scant information, constrained to a few time windows, because of poor pollen preservation. Stable isotope results for the total organic carbon fraction from three lithostratigraphic sections that span the past 40 kyr show shifts in delta C-13 values associated with changing contributions from C-3 and C-4 plants, suggesting this proxy can detect changes in these photosynthetic pathways, representative of Patagonian (and/or stream margin macrophytes) and Monte phytogeographic units, respectively. Climate and local factors, such as water availability in the basin, are inferred to be the main drivers of vegetation dynamics. The C/N ratios in a few samples show that organic matter sources are algae and/or phytoplankton, not solely C-3 or C-4 vascular plants. The delta C-13 record from Arroyo La Estacada is an example of how isotope geochemistry has overcome difficulties with pollen analysis and provided a reliable tool to investigate past vegetation changes in regions where C-3 and C-4 are differentially distributed. Isotope values during part of the Marine Isotope Stage 3 (MIS 3) and the middle Holocene are attributed to C-3 local floodplain plants, with a little or no contribution from regional terrestrial (Patagonian) vegetation. Late Pleistocene-Holocene palaeosols have a clear C-4 signal of terrestrial dominance, representative of Monte plants, thus, carbon isotope values constrain the early times of MIS 1, particularly where the Pleistocene Holocene transition occurs. A mixture of C-3 and C-4 values during the last 3-4 kyr is indicative of environmental conditions that prevail in the region today.

Rapid increase in atmospheric iodine levels in the North Atlantic since the mid-20th century

Cuevas, CA ;Maffezzoli, N ; Corella, JP ; Spolaor, A ; Vallelonga, P ; Kjaer, HA ; Simonsen, M ; Winstrup, M ; Vinther, B ; Horvat, C ; Fernandez, RP ; Kinnison, D ; Lamarque, JF ; Barbante, C ; Saiz-Lopez, A ; NATURE COMMUNICATIONS ,2018 ,9 ,-.

Atmospheric iodine causes tropospheric ozone depletion and aerosol formation, both of which have significant climate impacts, and is an essential dietary element for humans. However, the evolution of atmospheric iodine levels at decadal and centennial scales is unknown. Here, we report iodine concentrations in the RECAP ice-core (coastal East Greenland) to investigate how atmospheric iodine levels in the North Atlantic have evolved over the past 260 years (1750-2011), this being the longest record of atmospheric iodine in the Northern Hemisphere. The levels of iodine tripled from 1950 to 2010. Our results suggest that this increase is driven by anthropogenic ozone pollution and enhanced sub-ice phyto-plankton production associated with the recent thinning of Arctic sea ice. Increasing atmospheric iodine has accelerated ozone loss and has considerably enhanced iodine transport and deposition to the Northern Hemisphere continents. Future climate and anthropogenic forcing may continue to amplify oceanic iodine emissions with potentially significant health and environmental impacts at global scale.

Human Adipose-Derived Mesenchymal Stem/Stromal Cells Handling Protocols. Lipid Droplets and Proteins Double-Staining

Gojanovich, AD ;Gimenez, MC ; Masone, D ; Rodriguez, TM ; Dewey, RA ; Delgui, LR ; Bustos, DM ; Uhart, M ; FRONTIERS IN CELL AND DEVELOPMENTAL BIOLOGY ,2018 ,6 ,-.

Human Adipose-derived mesenchymal stem/stromal cells (hASCs) are of great interest because of their potential for therapeutic approaches. The method described here covers every single step necessary for hASCs isolation from subcutaneous abdominal adipose tissue, multicolor phenotyping by flow cytometry, and quantitative determination of adipogenic differentiation status by means of lipid droplets (LDs) accumulation, and Western blot analysis. Moreover, to simultaneously analyze both LDs accumulation and cellular proteins localization by fluorescence microscopy, we combined Oil Red O (ORO) staining with immunofluorescence detection. For LDs quantification we wrote a program for automatic ORO-stained digital image processing implemented in Octave, a freely available software package. Our method is based on the use of the traditional low cost neutral lipids dye ORO, which can be imaged both by bright-field and fluorescence microscopy. The utilization of ORO instead of other more expensive lipid-specific dyes, together with the fact that the whole method has been designed employing cost-effective culture reagents (standard culture medium and serum), makes it affordable for tight-budget research laboratories. These may be replaced, if necessary or desired, by defined xeno-free reagents for clinical research and applications.

Archaeological science in southern South America: An introduction

Morales, M ;Tessone, A ; Barberena, R ; JOURNAL OF ARCHAEOLOGICAL SCIENCE-REPORTS ,2018 ,18 ,606 -607 .

'To and fro' the southern Andean highlands (Argentina and Chile): Archaeometric insights on geographic vectors of mobility

Duran, VA ;Cortegoso, V ; Barberena, R ; Frigole, C ; Novellino, P ; Lucero, G ; Yebra, L ; Gasco, A ; Winocur, D ; Benitez, A ; Knudson, KJ ; JOURNAL OF ARCHAEOLOGICAL SCIENCE-REPORTS ,2018 ,18 ,668 -678 .

The Andes mountain range is one key physiographic feature of South America with the potential to have acted as a barrier and corridor for human societies. The goal of this paper is to assess from where and how were the highlands utilized during the last 2000 years, which is a key period witnessing the development of productive economies and changes in the organization of mobility. We develop a regional case study focused on the highland wetland Laguna del Diamante (3300 masl), which is a highly productive ecosystem only accessible during summer. This case is based on a multidisciplinary approach combining: a) geochemical characterization of obsidian sources located in the highlands and artifacts; b) isotopic approach to ranges of paleomobility of individuals by means of Sr-87/Sr-86; and c) stylistic study of ceramic assemblages.

Bending Lipid Bilayers: A Closed-Form Collective Variable for Effective Free-Energy Landscapes in Quantitative Biology

Masone, D ;Uhart, M ; Bustos, DM ; JOURNAL OF CHEMICAL THEORY AND COMPUTATION ,2018 ,14 ,2240 -2245 .

Curvature-related processes are of major importance during protein membrane interactions. The illusive simplicity of membrane reshaping masks a complex molecular process crucial for a wide range of biological functions like fusion, endo- and exocytosis, cell division, cytokinesis, and autophagy. To date, no functional expression of a reaction coordinate capable of biasing molecular dynamics simulations to produce membrane curvature has been reported. This represents a major drawback given that the adequate identification of proper collective variables to enhance sampling is fundamental for restrained dynamics techniques. In this work, we present a closed-form equation of a collective variable that induces bending in lipid bilayers in a controlled manner, allowing for straightforward calculation of free energy landscapes of important curvature-related events, using standard methods such as umbrella sampling and metadynamics. As a direct application of the collective variable, we calculate the bending free energies of a ternary lipid bilayer in the presence and the absence of a Bin/Amphiphysin/Rvs domain with an N-terminal amphipathic helix (N-BAR), a well-known peripheral membrane protein that induces curvature.

Bioindication of mercury, arsenic and uranium in the apple snail Pomacea canaliculata (Caenogastropoda, Ampullariidae): Bioconcentration and depuration in tissues and symbiotic corpuscles

Campoy-Diaz, AD ;Arribere, MA ; Guevara, SR ; Vega, IA ; CHEMOSPHERE ,2018 ,196 ,196 -205 .

Pomacea canaliculata is a mollusk potentially useful as a biomonitor species of freshwater quality. This work explores the ability of snail tissues and symbiotic corpuscles to bioconcentrate and depurate mercury, arsenic, and uranium. Adult snails cultured in metal-free reconstituted water were exposed for eight weeks (bioaccumulation phase) to water with Hg (2 mu gL(-1)), As (10 mu gL(-1)), and U (30 mu gL(-1)) and then returned to the reconstituted water for other additional eight weeks (depuration phase). Elemental concentrations in digestive gland, kidney, symbiotic corpuscles and particulate excreta were determined by neutron activation analysis. The glandular symbiotic occupancy was measured by morphometric analysis. After exposure, the kidney showed the highest concentration of Hg, while the digestive gland accumulated mainly As and U. The subcellular distribution in symbiotic corpuscles was similar to 71%, similar to 48%, and similar to 11% for U, Hg, and As, respectively. Tissue depuration between weeks 8 and 16 was variable amongst elements. At week 16, the tissue depuration of U was the highest (digestive gland = 92%; kidney = 80%), while it was lower for Hg (digestive gland = 51%; kidney = 53%). At week 16, arsenic showed a differential pattern of tissue depuration (digestive gland = 23%; kidney = 88%). The symbiotic detoxification of the three elements in excreta was fast between weeks 8 and 10 and it was slower after on. At the end of the depuration, each element distributed differentially in digestive gland and symbiotic corpuscles. Our findings show that symbiotic corpuscles, digestive gland and kidney P. canaliculata are sensitive places for biomonitoring of Hg, As and U. (C) 2017 Elsevier Ltd. All rights reserved.

Isoperimetric surfaces and area-angular momentum inequality in a rotating black hole in new massive gravity

Acena, A ;Lopez, E ; Llerena, M ; PHYSICAL REVIEW D ,2018 ,97 ,-.

We study the existence and stability of isoperimetric surfaces in a family of rotating black holes in new massive gravity. We show that the stability of such surfaces is determined by the sign of the hair parameter. We use the isoperimetric surfaces to find a geometric inequality between the area and the angular momentum of the black hole, conjecturing geometric inequalities for more general black holes.

Ion implantation in nanodiamonds: size effect and energy dependence

Shiryaev, AA ;Hinks, JA ; Marks, NA ; Greaves, G ; Valencia, FJ ; Donnelly, SE ; Gonzalez, RI ; Kiwi, M ; Trigub, AL ; Bringa, EM ; Fogg, JL ; Vlasov, II ; SCIENTIFIC REPORTS ,2018 ,8 ,-.

Nanoparticles are ubiquitous in nature and are increasingly important for technology. They are subject to bombardment by ionizing radiation in a diverse range of environments. In particular, nanodiamonds represent a variety of nanoparticles of significant fundamental and applied interest. Here we present a combined experimental and computational study of the behaviour of nanodiamonds under irradiation by xenon ions. Unexpectedly, we observed a pronounced size effect on the radiation resistance of the nanodiamonds: particles larger than 8 nm behave similarly to macroscopic diamond (i.e. characterized by high radiation resistance) whereas smaller particles can be completely destroyed by a single impact from an ion in a defined energy range. This latter observation is explained by extreme heating of the nanodiamonds by the penetrating ion. The obtained results are not limited to nanodiamonds, making them of interest for several fields, putting constraints on processes for the controlled modification of nanodiamonds, on the survival of dust in astrophysical environments, and on the behaviour of actinides released from nuclear waste into the environment.

Fossil cutin of Johnstonia coriacea (Corystospermaceae, Upper Triassic, Cacheuta, Argentina)

D'Angelo, JA ;Zodrow, EL ; INTERNATIONAL JOURNAL OF COAL GEOLOGY ,2018 ,189 ,70 -74 .

For the first time, a cutin polymer was obtained from specimens of Johnstonia coriacea (Corystospermales, Corystospermaceae) from the Upper Triassic of Cacheuta, Argentina. These are preserved as fossilized cuticles i.e., naturally macerated compressions under anoxic conditions. Laboratory oxidation reactions were used to obtain the cuticle, which after additional, long-term oxidation yielded the cutin polymer. Cutin, cuticles, and fossilized cuticles, were analyzed by semi-quantitative Fourier transform infrared (FTIR) spectroscopy. Cutin IR spectrum was mainly characterized by intense peaks of aliphatic stretching bands at 3000-2600 cm(-1), ester C=O groups centered at 1730-1715 cm(-1), and aromatic C=C absorption bands at 1645-1640 cm(-1). Values of semi-quantitative, IR-derived ratios of cutin were lower than those of the cuticle. The only exception was the notably higher C=O/C=C ratio found in cutin, which is supportive of the presence of ester C=0 groups. CHal/C=O value (0.8) of J. coriacea compares with those recorded for Iycopenicon esculentum (0.8; extant) and Macroneuropte is sheuchseti (0.9; Pennsylvanian), which indicates a similar cross-linking degree of the monomers characterizing the cutin of both extant and fossil taxa.

Negative Dipole Potentials and Carboxylic Polar Head Groups Foster the Insertion of Cell-Penetrating Peptides into Lipid Monolayers

Via, MA ;Del Popolo, MG ; Wilke, N ; LANGMUIR ,2018 ,34 ,3102 -3111 .

Cell-penetrating peptides (CPPs) are polycationic sequences of amino acids recognized as some of the most effective vehicles for delivering membrane-impermeable cargos into cells. CPPs can traverse cell membranes by direct translocation, and assessing the role of lipids on the membrane permeation process is important to convene a complete model of the CPP translocation. In this work, we focus on the biophysical basis of peptide-fatty acid interactions, analyzing how the acid-base and electrostatic properties of the lipids determine the CPP adsorption and incorporation into a Langmuir monolayer, focusing thus on the first two stages of the direct translocation mechanism. We sense the binding and insertion of the peptide into the lipid structure by measuring the changes in the surface pressure, the surface potential, and the reflectivity of the interface. We show that, beyond the presence of anionic moieties, negative dipole potentials and carboxylic polar head groups significantly promote the insertion of the peptide into the monolayer. On the basis of our results, we propose the appearance of stable CPP-lipid complexes whose kinetics of formation depends on the length of the lipids' hydrocarbon chains.

Geographic variation in life-history traits: factors shaping energy investment in reproduction in a highland dwelling rodent

Sassi, PL ;Menendez, J ; Cuevas, MF ; JOURNAL OF ZOOLOGY ,2018 ,304 ,210 -216 .

Variation in life-history traits is shaped by intrinsic and extrinsic factors. Climate influences the availability of energy and nutrients in the environment, and thus animals' energy balance, their allocation of resources to reproduction and ultimately, fitness. Temperature is reported as a prevailing influence on animals' investment in reproduction, and diverse hypotheses propose mechanisms by which it occurs. Central and external limits to energy acquisition have been traditionally assumed. Hence, digestive limitations, periods of low food availability or demanding cold conditions would restrict this input. However, under warm conditions endotherms also face the need to dissipate heat from metabolic processes. From this perspective, a high metabolic rate process, such as lactation, would be restricted under increasing ambient temperatures (T-a). Our research addresses the variation in reproductive parameters in Phyllotis xanthopygus, a rodent species broadly distributed in the west highlands and southern parts of South America. Across a pronounced elevation gradient in the central Andes Mountains we found that litter size is comparatively smaller in pregnant females collected at lower elevations. This is congruent with expectations from the heat dissipation limit hypothesis. To disentangle the role of temperature on this pattern, we bred individuals under two thermal treatments. We recorded no changes in the litter size, but pups' body mass was lower at higher T-a during lactation, also in agreement with decreased metabolism. Offspring size and number are relevant to a species' fitness. The evidence suggests that in P.xanthopygus these traits vary geographically and are shaped by T-a in the laboratory. A species that evolved in high altitudes, inhabits cold and temperate areas and is sensitive to T-a increases in the laboratory, appears as an excellent candidate to further explore the ecophysiology-thermal landscape interface, crucial to develop accurate predictive models of biodiversity dynamics.

Conformational changes, from beta-strand to alpha-helix, of the fatty acid-binding protein ReP1-NCXSQ in anionic lipid membranes: dependence with the vesicle curvature

Galassi, VV ;Salinas, SR ; Montich, GG ; EUROPEAN BIOPHYSICS JOURNAL WITH BIOPHYSICS LETTERS ,2018 ,47 ,165 -177 .

We studied the conformational changes of the fatty acid-binding protein ReP1-NCXSQ in the interface of anionic lipid membranes. ReP1-NCXSQ is an acidic protein that regulates the activity of the Na+/Ca2+ exchanger in squid axon. The structure is a flattened barrel composed of two orthogonal beta-sheets delimiting an inner cavity and a domain of two alpha-helix segments arranged as a hairpin. FTIR and CD spectroscopy showed that the interactions with several anionic lipids in the form of small unilamellar vesicles (SUVs) induced an increase in the proportion of helix secondary structure. Lower amount or no increase in alpha-helix was observed upon the interaction with anionic lipids in the form of large unilamellar vesicles (LUVs). The exception was 1,2-dimyristoyl-sn-glycero-3-phosphoglycerol (DMPG) that was equally efficien to to induce the conformational change both in SUVs and in LUVs. In solution, the infrared spectra of ReP1-NCXSQ at temperatures above the unfolding displayed a band at 1617 cm(-1) characteristic of aggregated strands. This band was not observed when the protein interacted with DMPG, indicating inhibition of aggregation in the interface. Similarly to the observed in L-BABP, another member of the fatty acid binding proteins, a conformational change in ReP1-NCXSQ was coupled to the gel to liquid-crystalline lipid phase transition.

Size of the Plastic Zone Produced by Nanoscratching

Alhafez, IA ;Ruestes, CJ ; Urbassek, HM ; TRIBOLOGY LETTERS ,2018 ,66 ,-.

Nanoscratching of ductile materials creates plastic zones surrounding the scratch groove. We approximate the geometry of these zones by a semicylinder with its axis oriented along the scratch direction. The radius and the length of the cylinder, as well as the length of the dislocations in the network created quantify the plasticity generated. Using molecular dynamics simulations, we characterize the plastic zones in six metals with fcc, bcc, and hcp crystal structures. We find that the plastic zone sizes after scratch are comparable to those after indent. Due to dislocation reactions, the dislocation networks simplify, reducing the total length of dislocations. As a consequence, the average dislocation density in the plastic zone stays roughly constant. Individually, we find exceptions from this simple picture. Fcc metals show strong plastic activity, which even increases during scratch. The hcp metals on the other side show the least plastic activity. Here the plasticity may be strongly reduced during scratch and particularly during tip withdrawal.

Discovery of the largest pterosaur from South America

David, LDO ;Riga, BJG ; Kellner, AWA ; CRETACEOUS RESEARCH ,2018 ,83 ,40 -46 .

A giant humerus (450 mm total length) belonging to one of the largest pterosaur recorded in South America is described. The specimen (UNCUYO-LD 350) was discovered in the Upper Cretaceous (upper Coniacian - lower Santonian) Plottier Formation of the Mendoza Province, northern Neuquen Basin, Argentina. It was found associated with a smaller pterosaur specimen represented by around thirty postcranial bones. The specimen is assigned to Tapejaroidea and show characters of both Tapejaridae and Azhdarchidae. Based on comparisions with other Azdharchidae species, a wingspan of 9.1 m is estimated for UNCUYO-LD 350, showing that giant pterosaurs were present in South America during the Upper Cretaceous. (C) 2017 Elsevier Ltd. All rights reserved.

Intra-regional classification of grape seeds produced in Mendoza province (Argentina) by multi-elemental analysis and chemometrics tools

Canizo, BV ;Escudero, LB ; Perez, MB ; Pellerano, RG ; Wuilloud, RG ; FOOD CHEMISTRY ,2018 ,242 ,272 -278 .

The feasibility of the application of chemometric techniques associated with multi-element analysis for the classification of grape seeds according to their provenance vineyard soil was investigated. Grape seed samples from different localities of Mendoza province (Argentina) were evaluated. Inductively coupled plasma mass spectrometry (ICP-MS) was used for the determination of twenty-nine elements (Ag, As, Ce, Co, Cs, Cu, Eu, Fe, Ga, Gd, La, Lu, Mn, Mo, Nb, Nd, Ni, Pr, Rb, Sm, Te, Ti, Tl, Tm, U, V, Y, Zn and Zr). Once the analytical data were collected, supervised pattern recognition techniques such as linear discriminant analysis (LDA), partial least square discriminant analysis (PLS-DA), k-nearest neighbors (k-NN), support vector machine (SVM) and Random Forest (RF) were applied to construct classification/discrimination rules. The results indicated that nonlinear methods, RF and SVM, perform best with up to 98% and 93% accuracy rate, respectively, and therefore are excellent tools for classification of grapes.

Provenance of obsidian artifacts from the Natural Protected Area Laguna del Diamante (Mendoza, Province Argentina) and upper Maipo valley (Chile) by LA-ICP-MS method

De Francesco, AM ;Barca, D ; Bocci, M ; Cortegoso, V ; Barberena, R ; Yebra, L ; Duran, V ; QUATERNARY INTERNATIONAL ,2018 ,468 ,134 -140 .

By means of inductively Coupled Plasma Mass Spectrometry associated with Laser Ablation (LA-ICP-MS) we analyzed several obsidian artifacts from the Natural Protected Area Laguna del Diamante (Mendoza, Argentina) and upper Maipo valley (Chile). This analytical method, almost non-destructive, is a powerful tool for the determination of trace elements and is very useful in characterizing and determining the provenance of obsidian fragments of archeological interest, although care must be taken to avoid or account for heterogeneities within obsidian such as microcrysts.

The interfacial electrostatic potential modulates the insertion of cell-penetrating peptides into lipid bilayers

Via, MA ;Klug, J ; Wilke, N ; Mayorga, LS ; Del Popolo, MG ; PHYSICAL CHEMISTRY CHEMICAL PHYSICS ,2018 ,20 ,5180 -5189 .

Cell-penetrating peptides (CPP) are short sequences of cationic amino-acids that show a surprising ability to traverse lipid bilayers. CPP are considered to be some of the most effective vectors to introduce membrane-impermeable cargos into cells, but the molecular basis of the membrane translocation mechanisms and its dependence on relevant membrane physicochemical properties have yet to be fully determined. In this paper we resort to Molecular Dynamics simulations and experiments to investigate how the electrostatic potential across the lipid/water interface affects the insertion of hydrophilic and amphipathic CPP into two-dimensional lipid structures. Simulations are used to quantify the effect of the transmembrane potential on the free-energy profile associated with the transfer of the CPP across a neutral lipid bilayer. It is found that the electrostatic bias has a relatively small effect on the binding of the peptides to the membrane surface, but that it significantly lowers the permeation barrier. A charge compensation mechanism, arising from the segregation of counter-ions while the peptide traverses the membrane, determines the shape and symmetry of the free-energy curves and underlines relevant mechanistic considerations. Langmuir monolayer experiments performed with a variety of amphiphiles model the incorporation of the CPP into the external membrane leaflet. It is shown that the dipole potential of the monolayer controls the extent of penetration of the CPP into the lipid aggregate, to a greater degree than its surface charge.

Morphological response of a cactus to cement dust pollution

Drack, JME ;Vazquez, DP ; ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY ,2018 ,148 ,571 -577 .

Cement dust from cement plants around the world has multiple negative effects on organisms and their environment. Cement's effects come from its strongly alkaline nature and high content of heavy metals. Previous studies on plants have documented that cement dust deposition can influence plant vegetative growth, the lipid and ionic composition of tissues, and foliar temperature. Here we evaluate the effects of cement dust coming from a plant in westem Argentina on the morphology of the cactus Tephrocactus aoracanthus. In sites located at 0.15 km, 2 km and 6 km from the cement plant, we recorded five morphological attributes of the cactus: length and number of spines, cladode (stem) diameter, and fresh and dry weight. We also transplanted plants in situ to evaluate the effect of distance from the cement plant. In addition, we set an experiment spreading cement dust weekly on the aerial and ground parts of the cactus. Results of our field observational and experimental studies indicate that cement dust deposition on aerial parts of the plant leads to increased spine length, number of spines, and wet and dry weights of cladodes.

Inorganic mercury in mammary cells: viability, metal uptake but efflux?

Maniero, MA ;Guerrero-Gimenez, ME ; Fanelli, MA ; Wuilloud, RG ; BIOMETALS ,2018 ,31 ,69 -80 .

The viability, cellular uptake and subcellular distribution of heavy metal Hg, were determined in human mammary cell lines (MCF-7, MDA-MB-231 and MCF-10A). It was observed that Hg had the capacity of being excluded from the cells with a different type of possible transporters. MCF-7 cells showed the lowest viability, while the other two cell lines were much more resistant to Hg treatments. The intracellular concentration of Hg was higher at lower exposure times in MCF-10A cells and MCF-7 cells; but as the time was increased only MDA-MB-231 showed the capacity to continue introducing the metal. In MCF-7 and MCF-10A cells the subcellular distribution of Hg was higher in cytosolic fraction than nucleus and membrane, but MDA-MB-231 showed membrane and nucleus fraction as the enriched one. The analysis of RNA-seq about the genes or family of genes that encode proteins which are related to cytotoxicity of Hg evidenced that MCF-10A cells and MCF-7 cells could have an active transport to efflux the metal. On the contrary, in MDA-MB-231 no genes that could encode active transporters have been found.

The Laser ablation of a metal foam: The role of electron-phonon coupling and electronic heat diffusivity

Rosandi, Y ;Grossi, J ; Bringa, EM ; Urbassek, HM ; JOURNAL OF APPLIED PHYSICS ,2018 ,123 ,-.

The incidence of energetic laser pulses on a metal foam may lead to foam ablation. The processes occurring in the foam may differ strongly from those in a bulk metal: The absorption of laser light, energy transfer to the atomic system, heat conduction, and finally, the atomistic processes-such as melting or evaporation-may be different. In addition, novel phenomena take place, such as a reorganization of the ligament network in the foam. We study all these processes in an Au foam of average porosity 79% and an average ligament diameter of 2.5 nm, using molecular dynamics simulation. The coupling of the electronic system to the atomic system is modeled by using the electron-phonon coupling, g, and the electronic heat diffusivity, kappa(e), as model parameters, since their actual values for foams are unknown. We show that the foam coarsens under laser irradiation. While kappa(e) governs the homogeneity of the processes, g mainly determines their time scale. The final porosity reached is independent of the value of g. Published by AIP Publishing.


Duran, V ;Novellino, P ; Menendez, L ; Gasco, A ; Marsh, E ; Barberena, R ; Frigole, C ; RELACIONES ,2018 ,43 ,55 -86 .

We present an interdisciplinary research of the human remains and grave goods recovered from the Barrio Ramos I burial, localized in the Uspallata Valley (Mendoza, Argentina). We reassess the traditional assignment of the site to the late 'Agroalfarero' period. Based on a bayesian analysis of the available radiocarbon dates for the site, and by integrating regional contexts with similar chronology, we suggest that Barrio Ramos I falls within the period of Inca domination. The analysis of lithic, ceramic, and bone artifacts recovered from the burial support this inference. By means of isotopic and bioarchaeological studies of the remains, we offer valuable insights on the lifeway and geographic origin of some of the individuals found at the site.

Nanotechnological Strategies as Smart ways for Diagnosis and Treatment of the Atherosclerosis

Gimenez, VMM ;Camargo, AB ; Kassuha, D ; Manucha, W ; CURRENT PHARMACEUTICAL DESIGN ,2018 ,24 ,4681 -4684 .

Atherosclerosis provokes a continuous worsening of affected vessels causing a blood flow diminution with several complications and with clinical manifestations that generally appear in advanced phases of the illness. Hence, the conventional therapies are not enough because the atherosclerotic injuries are often irrevocable. For this reason, emerges the necessity to implement smart ways of drug supply and develop new therapeutic targets that decrease the advance atherosclerotic lesion. It results due to particular interest to use new tools for prevention, diagnosis, and treatment of this cardiovascular disease, thus concentrating our attention to accomplish better management on the immune system. Finally, this mini-review highlights the most recent knowledge about nanotechnology as a robust, novel and promissory therapeutic option applied to atherosclerotic pathology, nevertheless, we also alert for possible issues associated with their use.

Feeding habits of the Asiatic red-bellied squirrel Callosciurus erythraeus introduced in Argentina

Zarco, A ;Benitez, VV ; Fasola, L ; Funes, G ; Guichon, ML ; HYSTRIX-ITALIAN JOURNAL OF MAMMALOGY ,2018 ,29 ,223 -228 .

Knowledge of food habits of invasive species is necessary to predict invasion success and potential interactions in the invaded community. The Asiatic red-bellied squirrel Callosciurus erythraeus has been introduced in Asia, Europe and South America. We studied feeding habits of red-bellied squirrels in Argentina in two sites 600 km apart where wild populations have become established. We used both faecal microhistological analysis and behavioural records to describe diet composition and feeding habits. We also analysed diet selection and the potential role of the squirrels as seed disperser. Squirrels consumed items from 35 species of exotic trees and shrubs and one native tree species; fruits and seeds represented the bulk of the diet in all seasons (faeces analysis: >44%; behavioural observations: >38%). Squirrels also consumed epiphytic and climbing plants, ferns, invertebrates, fungi, lichens, mosses and bird eggs. Diet composition varied throughout the year according to food availability. We did not find evidence of endozoochoric dispersal but we observed squirrels carrying and dropping nuts and acorns during transport. The consumption of a wide range of food items and species, the ability to modify the diet according to food availability, and the capacity to hoard food indicate that feeding habits of red-bellied squirrels favour their invasive potential.

Adipose-derived mesenchymal stem/stromal cells: from the lab bench to the basic concepts for clinical translation

Frontini-Lopez, YR ;Gojanovich, AD ; Masone, D ; Bustos, DM ; Uhart, M ; BIOCELL ,2018 ,42 ,67 -77 .

In the last years, much work has shown that the most effective repair system of the body is represented by stem cells, which are defined as undifferentiated precursors that own unlimited or prolonged self-renewal ability, which also have the potential to transform themselves into various cell types through differentiation. All tissues that form the body contain many different types of somatic cells, along with stem cells that are called 'mesenchymal stem (or stromal) cells' (MSC). In certain circumstances, some of these MSC migrate to injured tissues to replace dead cells or to undergo differentiation to repair it. The discovery of MSC has been an important step in regenerative medicine because of their high versatility. Moreover, the finding of a method to isolate MSC from adipose tissue, so called 'adipose-derived mesenchymal stem cells' (ASC), which share similar differentiation capabilities and isolation yield that is greater than other MSC, and less bioethical concerns compared to embryonic stem cells, have created self-praised publicity to procure almost any treatment with them. Here, we review the current techniques for isolation, culture and differentiation of human ASC (hASC), and describe them in detail. We also compile some advantages of the hASC over other stem cells, and provide some concepts that could help finding strategies to promote their therapeutic efficiency.

The impact of paralog genes: detection of copy number variation in spinal muscle atrophy patients

Laurito, S ;Cueto, JA ; Perez, J ; Roque, M ; BIOCELL ,2018 ,42 ,87 -91 .

Spinal muscular atrophy (SMA) is caused by dysfunction of the alpha motor neurons of the spinal cord. It is an autosomal recessive disease associated to the SMN1 gene, located in the subtelomeric region of 5q13. A paralog SMN2 gene is located at the centromeric region of the same chromosome, which apparently originated by an ancestral inverted duplication occurring only in humans. The exon sequence differs in two nucleotides in exon 7 and exon 8, which leads to an SMN2 transcript that lacks exon 7 and results in a truncated protein. Part (10%) of the SMN2 transcripts avoids the splicing of exon 7 but most of the copies are dysfunctional. In a disease scenario, the more SMN2 copies the higher possibility to restore at least partly the effects of SMN1 deficiency. Some therapeutic approaches are being developed to increase the expression of SMN2. To determine the number of SMN1 and SMN2 copies, the methodology must distinguish accurately between both genes. In this work, we present the results obtained using multiplex ligation-dependent probe amplification (MLPA) in 60 SMA suspected patients/carriers derived from different regions of Argentina. In 32 of these DNA samples we found alterations in SMN1. Among these, 16 presented a heterozygous deletion (carrier status) and 14 an homozygous deletion (patient status) in exon 7 and 8 of SMN1. In one case, exon 7 was found homozygously deleted but exon 8 presented a single copy, and in another case, exon 7 was found heterozygously deleted while exon 8 was normal. Almost half of the patients (7/15) presented a normal diploid number of SMN2 while the other half (8/15) presented an increased number. In this work we showed how a probe-based methodology such as MLPA was able to distinguish between the paralog genes and determine the amount of copies in DNA samples from suspected patients/carriers of SMA.

Application of tobacco hairy roots for the removal of malachite green from aqueous solutions: Experimental design, kinetic, equilibrium, and thermodynamic studies

Escudero, LB ;Agostini, E ; Dotto, GL ; CHEMICAL ENGINEERING COMMUNICATIONS ,2018 ,205 ,122 -133 .

Tobacco hairy roots (THR) were used to evaluate its potential for the biosorption and removal of malachite green (MG) from aqueous solutions. A 3(2) full factorial design was applied to study the effects of pH and THR concentration on the biosorption capacity. Under the optimal conditions (pH of 7.0 and THR concentration of 1gL(-1)), dye removal efficiency was around 92%. Experimental data obtained from kinetic studies demonstrated good concordance with the pseudo-second-order model. Equilibrium studies were developed and the data were evaluated by Langmuir, Freundlich, and Sips models, being the Sips model the most adequate (maximum biosorption capacity of 277.2mgg(-1)). Thermodynamically, the biosorption of MG on THR proved to be endothermic, spontaneous, and favorable. Desorption was feasible under acidic conditions and the biosorbent could be reused three times. THR was tested in simulated effluent and the removal percentage was 87%, demonstrating that this material is a promising biosorbent which can be used to treat colored wastewaters.

Biosorption of silver from aqueous solutions using wine industry wastes

Escudero, LB ;Vanni, G ; Duarte, FA ; Segger, T ; Dotto, GL ; CHEMICAL ENGINEERING COMMUNICATIONS ,2018 ,205 ,325 -337 .

The potential of wine industry wastes (grape peel, seed, and stem) as alternative biosorbents to remove Ag from aqueous media was investigated in this work. Wine industry wastes were washed, lyophilized and pulverized to obtain the biosorbents. The powdered biosorbents were characterized in detail and several batch experiments were performed to found the most suitable conditions for Ag biosorption. Kinetic, equilibrium, and thermodynamic studies were also performed. The interactions Ag-biosorbent were elucidated by analyses before and after the biosorption. For all wastes, the maximum removal percentages were found using a biosorbent dosage of 3.0 g L-1 at pH of 7.0. The kinetic data were well represented by the pseudo-first-order model. The equilibrium was satisfactorily represented by the Sips model. The maximum biosorption capacities, found at 298K, were: 41.7, 61.4, and 46.4 mg g(-1) for grape peel, seed, and stem, respectively. Thermodynamically, the biosorption was a spontaneous, favorable, exothermic, and enthalpy-controlled process. The magnitude of H-0 indicated a physical sorption. These results showed that the wine industry wastes can be considered alternative efficient, low-cost, and eco-friendly biosorbents to remove Ag from aqueous media.

A TEM-traceable physiologically functional gold nanoprobe that permeates non-endocytic cells

Berberian, MV ;Pocognoni, CA ; Mayorga, LS ; INTERNATIONAL JOURNAL OF NANOMEDICINE ,2018 ,13 ,8075 -8086 .

Background: Nanoparticles' intracellular fate requires proper internalization. Most cells make use of a battery of internalization pathways, but some are practically sealed, as they lack the biochemical machinery for cellular intake. Non-endocytic cells, such as mammals' spermatozoa, challenge standard drug-delivery strategies.

Variation analysis of the number of copies and methylene patterns in region 15q11-q13

Laurito, S ;Roque, M ; MEDICINA-BUENOS AIRES ,2018 ,78 ,1 -5 .

Human chromosome 15q11-q13 region is prone to suffer genetic alterations. Some genes of this region have a differential monoallelic imprinting-regulated expression pattern. Defects in imprinting regulation (IE), uniparental disomy (UPD) or copy number variation (CNV) due to chromosomal breakpoints (BP) in 15q11-q13 region, are associated with several diseases. The most frequent are Prader-Willi syndrome, Angelman syndrome and 15q11-q13 microduplication syndrome. In this work, we analyzed DNA samples from 181 patients with phenotypes which were compatible with the above-mentioned diseases, using Methyl specific-multiplex ligation-dependent probe amplification (MS-MLPA). We show that, of the 181 samples, 39 presented alterations detectable by MS-MLPA. Of those alterations, 61.5% (24/39) were deletions, 5.1% (2/39) duplications and 33.3% (13/39) UPD/IE. The CNV cases were 4 times more frequent than UPD/IE (OR=4; IC 95%: 1.56-10.25), consistent with the literature. Among the CNVs, two atypical cases allow to postulate new possible BP sites that have not been reported previously in the literature.

Markov Decision Process to Dynamically Adapt Spots Instances Ratio on the Autoscaling of Scientific Workflows in the Cloud

Gari, Y ;Monge, DA ; Mateos, C ; Garino, CG ; HIGH PERFORMANCE COMPUTING ,2018 ,796 ,353 -369 .

Spot instances are extensively used to take advantage of large-scale Cloud infrastructures at lower prices than traditional on-demand instances. Autoscaling scientific workflows in the Cloud considering both spot and on-demand instances presents a major challenge as the autoscalers have to determine the proper amount and type of virtual machine instances to acquire, dynamically adjusting the number of instances under each pricing model (spots or on-demand) depending on the workflow needs. Under budget constraints, this adjustment is performed by an assignment policy that determines the suitable proportion of the available budget intended for each model. We propose an approach to derive an adaptive budget assignment policy able to reassign the budget at any point in the workflow execution. Given the inherent variability of the resources in a Cloud, we formalize the described problem as a Markov Decision Process and derive adaptive policies based on other baseline policies. Experiments demonstrate that our policies outperform all the baseline policies in terms of makespan and most of them in terms of cost. These promising results encourage the future study of new strategies aiming to find optimal budget policies applied to the execution of workflows on the Cloud.

Hunter-gatherers and herders in the Andes (San Juan, Argentina): changes in technological organization during the Holocene

Castro, SC ;ARQUEOLOGIA ,2018 ,24 ,99 -121 .

The ARQ-18 rock shelter, located in the northwestern cordillera of the San Juan Province of Argentina, has a long occupational sequence (ca. 8,000 years BP). A middle Holocene hiatus of 1,600 years separates high residential mobility hunter-gatherer occupation from transhumant herder occupation. This article evaluates changes in the organization of lithic technology linked to transformations in subsistence and mobility. Our analysis addresses the origin of resources, artifact density, reduction sequences, artifact variability, and technical classes. The data demonstrates that the transition to a diversified economy resulted in longer stays, a greater diversity of tasks, the use of mostly expedient and opportunistic strategies, and a decrease in time invested in the making of lithic implements. Curation strategies are linked to a continuity of hunting as an economic activity.

Observer Effect: How Intercepting HTTPS Traffic Forces Malware to Change Their Behavior

Erquiaga, MJ ;Garcia, S ; Garino, CG ; COMPUTER SCIENCE (CACIC 2017) ,2018 ,790 ,272 -281 .

During the last couple of years there has been an important surge on the use of HTTPs by malware. The reason for this increase is not completely understood yet, but it is hypothesized that it was forced by organizations only allowing web traffic to the Internet. Using HTTPs makes malware behavior similar to normal connections. Therefore, there has been a growing interest in understanding the usage of HTTPs by malware. This paper describes our research to obtain large quantities of real malware traffic using HTTPs, our use of man-in-the-middle HTTPs interceptor proxies to open and study the content, and our analysis of how the behavior of the malware changes after being intercepted. The research goal is to understand how malware uses HTTPs and the impact of intercepting its traffic. We conclude that the use of an interceptor proxy forces the malware to change its behavior and therefore should be carefully considered before being implemented.

Social mating system, male parental care contribution and life history traits of a southern Sedge Wren (Cistothorus platensis platensis) population: a comparison with northern Sedge Wrens (Cistothorus platensis stellaris)

Llambias, PE ;Garrido, PS ; Jefferies, MM ; Fernandez, GJ ; JOURNAL OF ORNITHOLOGY ,2018 ,159 ,221 -231 .

The study of geographic variation of social mating systems can shed new light on our understanding of how ecological variables shape extant mating associations. We report data on the social mating system, parental care and life history traits of a temperate population of southern Sedge Wrens (Cistothorus platensis platensis) in South America. We compared our results with published records of two temperate populations of northern Sedge Wren (Cistothorus platensis stellaris) in North America. The southern temperate population had a lower social polygyny rate, greater male contribution to feeding nestlings and smaller clutch sizes than northern temperate populations. A similar pattern of low rates of social polygyny and smaller clutch sizes in the south versus moderate rates of social polygyny and bigger clutch sizes in the north has been reported for the House Wren (Troglodytes aedon). This suggests that different selective forces may be operating in northern and southern wren populations. Future work in additional study populations is essential to establishing the generality of our results.

Interaction frequency, network position, and the temporal persistence of interactions in a plant-pollinator network

Chacoff, NP ;Resasco, J ; Vazquez, DP ; ECOLOGY ,2018 ,99 ,21 -28 .

Ecological interactions are highly dynamic in time and space. Previous studies of plant-animal mutualistic networks have shown that the occurrence of interactions varies substantially across years. We analyzed interannual variation of a quantitative mutualistic network, in which links are weighted by interaction frequency. The network was sampled over six consecutive years, representing one of the longest time series for a community-wide mutualistic network. We estimated the interannual similarity in interactions and assessed the determinants of their persistence. The occurrence of interactions varied greatly among years, with most interactions seen in only one year (64%) and few (20%) in more than two years. This variation was associated with the frequency and position of interactions relative to the network core, so that the network consisted of a persistent core of frequent interactions and many peripheral, infrequent interactions. Null model analyses suggest that species abundances play a substantial role in generating these patterns. Our study represents an important step in the study of ecological networks, furthering our mechanistic understanding of the ecological processes driving the temporal persistence of interactions.

TP73 DNA methylation and upregulation of Delta Np73 are associated with an adverse prognosis in breast cancer

Gomez, LC ;Sottile, ML ; Guerrero-Gimenez, ME ; Zoppino, FCM ; Redondo, AL ; Gago, FE ; Orozco, JI ; Tello, OM ; Roque, M ; Nadin, SB ; Marzese, DM ; Vargas-Roig, LM ; JOURNAL OF CLINICAL PATHOLOGY ,2018 ,71 ,52 -58 .

Aim Accumulated evidence suggests that aberrant methylation of the TP73 gene and increased levels of Delta Np73 in primary tumours correlate with poor prognosis. However, little is known regarding the transcriptional and functional regulation of the TP73 gene in breast cancer. The aim of the present study was to determine the expression of the Delta Np73 isoform, its relationship with DNA methylation of TP73 and their clinical prognostic significance in breast cancer patients.