Facultad de Ciencias Exactas y Naturales

Publicaciones 2019

Nanoindentation into a high-entropy alloy - An atomistic study

Alhafez, IA ;Ruestes, CJ ; Bringa, EM ; Urbassek, HM ; JOURNAL OF ALLOYS AND COMPOUNDS ,2019 ,803 ,618 -624 .

The plastic response of a high-entropy alloy is explored by means of simulated nanoindentation tests. We compare nanoindentation into the Cantor alloy - an equi-atomic CoCrFeMnNi fcc solid solution - with that into an elemental Ni fcc single crystal. Using molecular dynamics simulation, strong differences in the plastic behavior are identified. While the total length of the dislocation network in the Cantor alloy is higher than in Ni, the size of the plastic zone is considerably restricted. Dislocations are more localized in the Cantor alloy, both during indentation, but also during retraction of the indenter; emission of prismatic loops is absent in the Cantor alloy. Besides dislocation-mediated plasticity, considerable twinning occurs. No amorphization could be observed. These simulation results are in good qualitative agreement with our current knowledge of plasticity in high entropy alloys. (C) 2019 Elsevier B.V. All rights reserved.

Adsorption and insertion of polyarginine peptides into membrane pores: The trade-off between electrostatics, acid-base chemistry and pore formation energy

Ramirez, PG ;Del Popolo, MG ; Vila, JA ; Szleifer, I ; Longo, GS ; JOURNAL OF COLLOID AND INTERFACE SCIENCE ,2019 ,552 ,701 -711 .

The mechanism that arginine-rich cell penetrating peptides (ARCPPs) use to translocate lipid membranes is not entirely understood. In the present work, we develop a molecular theory that allows to investigate the adsorption and insertion of ARCPPs on membranes bearing hydrophilic pores. This method accounts for size, shape, conformation, protonation state and charge distribution of the peptides; it also describes the state of protonation of acidic membrane lipids. We present a systematic investigation of the effect of pore size, peptide concentration and sequence length on the extent of peptide adsorption and insertion into the pores. We show that adsorption on the intact (non-porated) lipid membrane plays a key role on peptide translocation. For peptides shorter than nona-arginine, adsorption on the intact membrane increases significantly with chain length, but it saturates for longer peptides. However, this adsorption behavior only occurs at relatively low peptide concentrations; increasing peptide concentration favors adsorption of the shorter molecules. Adsorption of longer peptides increases the intact membrane negative charge as a result of further deprotonation of acidic lipids. Peptide insertion into the pores depends non-monotonically on pore radius, which reflects the short range nature of the effective membrane-peptide interactions. The size of the pore that promotes maximum adsorption depends on the peptide chain length. Peptide translocation is a thermally activated process, so we complement our thermodynamic approach with a simple kinetic model that allows to rationalize the ARCPPs translocation rate in terms of the free energy gain of adsorption, and the energy cost of creating a transmembrane pore with peptides in it. Our results indicate that strategies to improve translocation efficiency should focus on enhancing peptide adsorption. (C) 2019 Elsevier Inc. All rights reserved.

14-3-3 epsilon protein-immobilized PCL-HA electrospun scaffolds with enhanced osteogenicity

Rivero, G ;Aldana, AA ; Lopez, YRF ; Liverani, L ; Boccacini, AR ; Bustos, DM ; Abraham, GA ; JOURNAL OF MATERIALS SCIENCE-MATERIALS IN MEDICINE ,2019 ,30 ,701 -711 .

Adipose-derived mesenchymal stem cells (ASCs) accelerate the osteointegration of bone grafts and improve the efficiency in the formation of uniform bone tissue, providing a practical and clinically attractive approach in bone tissue regeneration. In this work, the effect of nanofibrous biomimetic matrices composed of poly(epsilon-caprolactone) (PCL), nanometric hydroxyapatite (nHA) particles and 14-3-3 protein isoform epsilon on the initial stages of human ASCs (hASCs) osteogenic differentiation was investigated. The cells were characterized by flow cytometry and induction to differentiation to adipogenic and osteogenic lineages. The isolated hASCs were induced to differentiate to osteoblasts over all scaffolds, and adhesion and viability of the hASCs were found to be similar. However, the activity of alkaline phosphatase (ALP) as early osteogenic marker in the PCL-nHA/protein scaffold was four times higher than in PCL-nHA and more than five times than the measured in neat PCL.

Hydrochemical processes, variability and natural background levels of Arsenic in groundwater of northeastern Mendoza, Argentina

Gomez, L ;Canizo, B ; Lana, B ; Zalazar, G ; Wuilloud, R ; Aravena, R ; JOURNAL OF IBERIAN GEOLOGY ,2019 ,45 ,365 -382 .

Northeastern Mendoza is an arid area dominated by stabilized dunes and paleochannels. Groundwater is the main source of water for domestic and subsistence economy. Two types of wells are used for groundwater withdrawal. Wells operated by conventional windmills or pumps (Ws) and local traditional bucket wells operated manually (BWs). These wells are drugged a few cm below the water table, normally with a diameter of 1 m, remain always open and are located near corrals. The aim of this study was to evaluate the processes that control As in groundwater used As drinking water by rural communities. The study approach included an assessment of the natural as background levels and the use of environmental isotopes (delta O-18 and delta H-2) to determine the origin of groundwater and improve the conceptual model for groundwater flow. Significant statistical differences were found between the chemical features of groundwater from Ws and BWs. The conceptual hydrogeologic model supported by isotopic data indicated that groundwater recharge was from the main Mendoza/Tunuyan Rivers in remote areas and that local rainwater recharge is negligible. The isotopic data suggests that a faster groundwater flow recharge could occur without any influence of a previous evaporation process. The natural As background level was 104 mu g/L, with a range of between 8.6 and 394 mu g/L. The average As concentration in Ws was 114 mu g/L. Water from BWs showed higher average As concentration of 235 mu g/L with a higher dispersion, high HCO3-, NO3- PO4-3 and Cl- concentrations, and the lowest concentrations of O-2 with greater turbidity than groundwater from Ws. The increase in As concentrations in groundwater of NE Mendoza is not related to evaporation processes despite arid climatic conditions. According to the oxidizing environment in the aquifer, high pH and very fine sediments, adsorption-desorption processes from solid surfaces were the determining factors for the availability and spatial variability of As in groundwater. Spatial variability was related to type of well rather than to geomorphologic units or to flow direction. The design of bucket wells, near corrals, allows the input of windblown sediments and leachate from livestock units creating point sources of As contamination in water used for human consumption.

Molecular structure of the cuticles of Dicroidium and Johnstonia (Corystospermaceae, Triassic, Argentina). Ecophysiological adaptations of two chemically indistinguishable, morphology-based taxa

D'Angelo, JA ;REVIEW OF PALAEOBOTANY AND PALYNOLOGY ,2019 ,268 ,109 -124 .

Cuticles of compression-preserved Dicroidium odontopteroides and Johnstonia coriacea (Corystospermaceae, Upper Triassic, Mendoza, Argentina) are spectrochemically analyzed. The objectives included (i) studying the chemical resistance of cuticles to different oxidative conditions to gain new insights into their fine molecular structure and its likely (ii) chemotaxonomical and (iii) paleoecophysiological implications. Two experimental procedures are employed to obtain the cuticles from the compressions: (a) room-temperature (25 degrees C and up to 75 min) and (b) high-temperature (500 degrees C and up to 50 min) oxidative reactions using Schulze's reagent. Details of the molecular structure (i.e., functional groups) of cuticles are studied using Fourier transform infrared (FTIR) spectroscopy followed by data evaluation using principal component analysis and one-way ANOVA test. Morphological changes as a function of different oxidative conditions are monitored by scanning electron microscopy. Results indicate that the geomacropolymers composing the cuticles of both taxa are chemically characterized by high contents of aliphatic compounds with relatively smaller amounts of aromatic hydrocarbons. The presence of considerable contents of carbonyl groups in the cuticles indicates likely ester chemical "bridges" that cross-link aliphatic and aromatic hydrocarbons. These chemical bonds "strengthen" the molecular structure, thus increasing the overall mechanical and chemical resistance of the cuticle. Conclusions include: (i) the cuticles of both taxa are extraordinarily resistant to extremely harsh chemical conditions, which modified neither morphology nor chemical structure; (ii) independently of the oxidative procedure employed, the two taxa cannot be statistically differentiated using the cuticular FTIR information; (iii) the high chemical resistance of the studied cuticles represents likely ecophysiological adaptations of the once living plants to survive stressful environmental conditions. They could have included high temperatures, elevated CO2 concentrations, seasonal drought, and nutrient-deficient, acidic soils exposed to intensive solar irradiation, and eventual acid (H2SO4) precipitations. Chemical results are in agreement with taphonomic, sedimentological, paleopedological and (micro- and macro-) morphological data, which indicate that the studied plants were likely opportunistic and stress-tolerant colonizers that dominated flood-disturbed, waterlogged lowlands.

Adaptation of the Andean Toad Rhinella spinulosa (Anura: Bufonidae) at Low Temperatures: The Role of Glucose as Cryoprotectant

Rodriguez, CY ;Bustos, DA ; Sanabria, EA ; PHYSIOLOGICAL AND BIOCHEMICAL ZOOLOGY ,2019 ,92 ,473 -480 .

We studied the role of plasma glucose concentration on individuals of Rhinella spinulosa in response to annual temperature variation and freezing temperatures. Measurements and collection of toads were made every 2 mo for a period of 1 yr. To determine whether toads were exposed to low temperatures in their habitat, we proceeded with the study of operating temperatures (T (e)). The measures of operating temperature were determined by using plaster models placed in the field, simulating the situation where toads are outside or inside shelters, for which it was determined that individuals in the winter season would have been exposed to temperatures below 0 degrees C. Glucose levels measured in field specimens showed an annual variation, but laboratory specimens exposed to freezing temperatures had higher plasma glucose levels than field toads. Furthermore, the crystallization temperature for the species has been recorded at -1.6 degrees C. The increase in glucose concentration indicates its possible use as a cryoprotectant before freezing events in this species of frogs and also in the coldest months at temperatures below 0 degrees C.

Multiscale approach to electron transport dynamics

Bustamante, CM ;Ramirez, FF ; Sanchez, CG ; Scherlis, DA ; JOURNAL OF CHEMICAL PHYSICS ,2019 ,151 ,473 -480 .

Molecular simulations of transport dynamics in nanostructures usually require the implementation of open quantum boundary conditions. This can be instrumented in different frameworks including Green's functions, absorbing potentials, or the driven Liouville von Neumann equation, among others. In any case, the application of these approaches involves the use of large electrodes that introduce a high computational demand when dealing with first-principles calculations. Here, we propose a hybrid scheme where the electrodes are described at a semiempirical, tight binding level, coupled to a molecule or device represented with density functional theory (DFT). This strategy allows us to use massive electrodes at a negligible computational cost, preserving the accuracy of the DFT method in the modeling of the transport properties, provided that the electronic structure of every lead is properly defined to behave as a conducting fermionic reservoir. We study the nature of the multiscale coupling and validate the methodology through the computation of the tunneling decay constant in polyacetylene and of quantum interference effects in an aromatic ring. The present implementation is applied both in microcanonical and grand-canonical frameworks, in the last case using the Driven Liouville von Neumann equation, discussing the advantages of one or the other. Finally, this multiscale scheme is employed to investigate the role of an electric field applied normally to transport in the conductance of polyacetylene. It is shown that the magnitude and the incidence angle of the applied field have a considerable effect on the electron flow, hence constituting an interesting tool for current control in nanocircuits. Published under license by AIP Publishing.

How meaning unfolds in neural time: Embodied reactivations can precede multimodal semantic effects during language processing

Garcia, AM ;Moguilner, S ; Torquati, K ; Garcia-Marco, E ; Herrera, E ; Munoz, E ; Castillo, EM ; Kleineschay, T ; Sedeno, L ; Ibanez, A ; NEUROIMAGE ,2019 ,197 ,439 -449 .

Research on how the brain construes meaning during language use has prompted two conflicting accounts. According to the 'grounded view', word understanding involves quick reactivations of sensorimotor (embodied) experiences evoked by the stimuli, with simultaneous or later engagement of multimodal (conceptual) systems integrating information from various sensory streams. Contrariwise, for the 'symbolic view', this capacity depends crucially on multimodal operations, with embodied systems playing epiphenomenal roles after comprehension. To test these contradictory hypotheses, the present magnetoencephalography study assessed implicit semantic access to grammatically constrained action and non-action verbs (n =100 per category) while measuring spatiotemporally precise signals from the primary motor cortex (M1, a core region subserving bodily movements) and the anterior temporal lobe (ATL, a putative multimodal semantic hub). Convergent evidence from sensor- and source-level analyses revealed that increased modulations for action verbs occurred earlier in M1 (similar to 130-190 ms) than in specific ATL hubs (similar to 250-410 ms). Moreover, machine-learning decoding showed that trial-by-trial classification peaks emerged faster in M1 (similar to 100-175 ms) than in the ATL (similar to 345-500 ms), with over 71% accuracy in both cases. Considering their latencies, these results challenge the 'symbolic view' and its implication that sensorimotor mechanisms play only secondary roles in semantic processing. Instead, our findings support the 'grounded view', showing that early semantic effects are critically driven by embodied reactivations and that these cannot be reduced to post-comprehension epiphenomena, even when words are individually classified. Briefly, our study offers non-trivial insights to constrain fine-grained models of language and understand how meaning unfolds in neural time.

Removal of Crystal Violet from Natural Water and Effluents Through Biosorption on Bacterial Biomass Isolated from Rhizospheric Soil

Canizo, BV ;Agostini, E ; Oller, ALW ; Dotto, GL ; Vega, IA ; Escudero, LB ; WATER AIR AND SOIL POLLUTION ,2019 ,230 ,439 -449 .

It was investigated the potential of Rhodococcus erythropolis AW3 as a biosorbent for the removal of crystal violet (CV) dye from natural water and real effluents. The biosorbent was characterized by flow cytometry, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy X-ray dispersive spectroscopy (EDS), and point of zero charge (pH(ZPC)). Batch biosorption experiments were performed to optimize different parameters involved in the biosorption process. The equilibrium was reached at 90 min at the optimum biosorbent dose of 0.50 g L-1 and pH of 9.0. Results indicated that Langmuir isotherm model was the most suitable to represent the experimental data, and the highest biosorption capacity was 289.8 mg g(-1). Kinetic data were well fitted with the pseudo-second-order model. The thermodynamic study showed that the process was favorable, exothermic, and associated with an increase of entropy. Finally, it was demonstrated that the biosorption process using Rhodococcus erythropolis AW3 could be successfully applied to remove CV from natural water and effluents derived from clinical and industrial activities.

Modeling the Sources and Chemistry of Polar Tropospheric Halogens (Cl, Br, and I) Using the CAM-Chem Global Chemistry-Climate Model

Fernandez, RP ;Carmona-Balea, A ; Cuevas, CA ; Barrera, JA ; Kinnison, DE ; Lamarque, JF ; Blaszczak-Boxe, C ; Kim, K ; Choi, W ; Hay, T ; Blechschmidt, AM ; Schonhardt, A ; Burrows, JP ; Saiz-Lopez, A ; JOURNAL OF ADVANCES IN MODELING EARTH SYSTEMS ,2019 ,11 ,2259 -2289 .

Current chemistry climate models do not include polar emissions and chemistry of halogens. This work presents the first implementation of an interactive polar module into the very short-lived (VSL) halogen version of the Community Atmosphere Model with Chemistry (CAM-Chem) model. The polar module includes photochemical release of molecular bromine, chlorine, and interhalogens from the sea-ice surface, and brine diffusion of iodine biologically produced underneath and within porous sea-ice. It also includes heterogeneous recycling of inorganic halogen reservoirs deposited over fresh sea-ice surfaces and snow-covered regions. The polar emission of chlorine, bromine, and iodine reach approximately 32, 250, and 39 Gg/year for Antarctica and 33, 271, and 4 Gg/year for the Arctic, respectively, with a marked seasonal cycle mainly driven by sunlight and sea-ice coverage. Model results are validated against polar boundary layer measurements of ClO, BrO, and IO, and satellite BrO and IO columns. This validation includes satellite observations of IO over inner Antarctica for which an iodine "leapfrog" mechanism is proposed to transport active iodine from coastal source regions to the interior of the continent. The modeled chlorine and bromine polar sources represent up to 45% and 80% of the global biogenic VSLCl and VSLBr emissions, respectively, while the Antarctic sea-ice iodine flux is similar to 10 times larger than that from the Southern Ocean. We present the first estimate of the contribution of polar halogen emissions to the global tropospheric halogen budget. CAM-Chem includes now a complete representation of halogen sources and chemistry from pole-to-pole and from the Earth's surface up to the stratopause.

Junin Virus Promotes Autophagy To Facilitate the Virus Life Cycle

Roldan, JS ;Candurra, WA ; Colombo, MI ; Delgui, LR ; JOURNAL OF VIROLOGY ,2019 ,93 ,2259 -2289 .

Junin virus (JUNV), a member of the family Arenaviridae, is the etiological agent of Argentine hemorrhagic fever (AHF), a potentially deadly endemicepidemic disease affecting the population of the most fertile farming land of Argentina. Autophagy is a degradative process with a crucial antiviral role; however, several viruses subvert the pathway to their benefit. We determined the role of autophagy in JUNV-infected cells by analyzing LC3, a cytoplasmic protein (LC3-I) that becomes vesicle membrane associated (LC3-II) upon induction of autophagy. Cells overexpressing enhanced green fluorescent protein (EGFP)-LC3 and infected with JUNV showed an increased number of LC3 punctate structures, similar to those obtained after starvation or bafilomycin A1 treatment, which leads to autophagosome induction or accumulation, respectively. We also monitored the conversion of LC3-I to LC3-II, observing LC3-II levels in JUNV-infected cells similar to those observed in starved cells. Additionally, we kinetically studied the number of LC3 dots after JUNV infection and found that the virus activated the pathway as early as 2 h postinfection (p.i.), whereas the UV-inactivated virus did not induce the pathway. Cells subjected to starvation or pretreated with rapamycin, a pharmacological autophagy inductor, enhanced virus yield. Also, we assayed the replication capacity of JUNV in Atg5 knockout or Beclin 1 knockdown cells (both critical components of the autophagic pathway) and found a significant decrease in JUNV replication. Taken together, our results constitute the first study indicating that JUNV infection induces an autophagic response, which is functionally required by the virus for efficient propagation.

The complete organelle genomes of Physochlaina orientalis: Insights into short sequence repeats across seed plant mitochondrial genomes

Gandini, CL ;Garcia, LE ; Abbona, CC ; Sanchez-Puerta, MV ; MOLECULAR PHYLOGENETICS AND EVOLUTION ,2019 ,137 ,274 -284 .

Short repeats (SR) play an important role in shaping seed plant mitochondrial genomes (mtDNAs). However, their origin, distribution, and relationships across the different plant lineages remain unresolved. We focus on the angiosperm family Solanaceae that shows great variation in repeat content and extend the study to a wide diversity of seed plants. We determined the complete nucleotide sequences of the organellar genomes of the medicinal plant Physochlaina orientalis (Solanaceae), member of the tribe Hyoscyameae. To understand the evolution of the P. orientalis mtDNA we made comparisons with those of five other Solanaceae. P. orientalis mtDNA presents the largest mitogenome (similar to 685 kb in size) among the Solanaceae and has an unprecedented 8-copy repeat family of similar to 8.2 kb in length and a great number of SR arranged in tandem-like structures. We found that the SR in the Solanaceae share a common origin, but these only expanded in members of the tribe Hyoscyameae. We discuss a mechanism that could explain SR formation and expansion in P. orientalis and Hyoscyamus niger. Finally, the great increase in plant mitochondrial data allowed us to systematically extend our repeat analysis to a total of 136 seed plants to characterize and analyze for the first time families of SR among seed plant mtDNAs.

Dung beetles and nutrient cycling in a dryland environment

Maldonado, MB ;Aranibar, JN ; Serranoa, AM ; Chacoff, NP ; Vazquez, DP ; CATENA ,2019 ,179 ,66 -73 .

Insects are involved in the biogeochemical cycles of multiple elements and influence soil fertility. In particular, soil insects and the functions that they support can affect the response of terrestrial ecosystems to environmental changes. We experimentally studied the role of dung beetles as recyclers of cow dung in drylands of the Central Monte in mid-western Argentina; and we extrapolated these results to ecosystem impact in a grazing field, considering the dung beetle's abundance in summer. We conducted experiments with four species of dung beetles (Sulcophanaeus imperator, Eucranium arachnoides, Digitonthophagus gazelle and Malagoniella puncticollis), and quantified their abundance on the field. Dung beetles incorporated nitrogen, ammonium, and phosphorous to the soil, but this activity varied substantially among species. The highest quantity of organic matter, nitrogen and phosphate was incorporated to the soil by S. imperator, one of the larger beetle studied. While the per capita effect of S. imperator is superior to other species studied, the impact on the ecosystem of the invasive D. gazelle might be superior due to their major abundance in grazing fields. Our results highlight the importance of considering both components, per capita effect and abundance, to estimate with more reliability the relative importance of dung beetle species. Given that the effect of dung beetles on nutrient cycling is variable among species, and their abundance is variable in space, it is important to conserve beetle diversity in order to maximize their beneficial impacts on soils. Therefore, dung beetle effect on soil might be crucial in drylands to mitigate the nitrogen losses caused by grazing.

Functional and evolutionary perspectives on gill structures of an obligate air-breathing, aquatic snail

Rodriguez, C ;Prieto, GI ; Vega, IA ; Castro-Vazquez, A ; PEERJ ,2019 ,7 ,66 -73 .

Ampullariids are freshwater gastropods bearing a gill and a lung, thus showing different degrees of amphibiousness. In particular, Pomacea canaliculata (Caenogastropoda, Ampullariidae) is an obligate air-breather that relies mainly or solely on the lung for dwelling in poorly oxygenated water, for avoiding predators, while burying in the mud during aestivation, and for oviposition above water level. In this paper, we studied the morphological peculiarities of the gill in this species. We found (1) the gill and lung vasculature and innervation are intimately related, allowing alternation between water and air respiration; (2) the gill epithelium has features typical of a transporting rather than a respiratory epithelium; and (3) the gill has resident granulocytes within intraepithelial spaces that may serve a role for immune defence. Thus, the role in oxygen uptake may be less significant than the roles in ionic/osmotic regulation and immunity. Also, our results provide a morphological background to understand the dependence on aerial respiration of Pomacea canaliculata. Finally, we consider these findings from a functional perspective in the light of the evolution of amphibiousness in the Ampullariidae, and discuss that master regulators may explain the phenotypic convergence of gill structures amongst this molluscan species and those in other phyla.

Hopanoids Like Sterols Form Compact but Fluid Films

Mangiarotti, A ;Galassi, VV ; Puentes, EN ; Oliveira, RG ; Del Popolo, MG ; Wilke, N ; LANGMUIR ,2019 ,35 ,9848 -9857 .

Hopanoids are pentacyclic molecules present in membranes from some bacteria, recently proposed as sterol surrogates in these organisms. Diplopterol is an abundant hopanoid that, similar to sterols, does not self-aggregate in lamellar structures when pure, but forms monolayers at the air-water interface. Here, we analyze the interfacial behavior of pure diplopterol and compare it with sterols from different organisms: cholesterol from mammals, ergosterol from fungi, and stigmasterol from plants. We prepared Langmuir monolayers of the compounds and studied their surface properties using different experimental approaches and molecular dynamics simulations. Our results indicate that the films formed by diplopterol, despite being compact with low mean molecular areas, high surface potentials, and high refractive index, depict shear viscosity values similar to that for fluid films. Altogether, our results reveal that hopanoids have similar interfacial behavior than that of sterols, and thus they may have the capacity of modulating bacterial membrane properties in a similar way sterols do in eukaryotes.

Stopping of porous projectiles in granular targets

Planes, MB ;Millan, EN ; Urbassek, HM ; Bringa, EM ; MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY ,2019 ,487 ,L13 -L17 .

Using granular mechanics, we determine the stopping force acting on spherical granular projectiles impinging on a flat granular bed. We find that the stopping force is proportional to the impact energy, as in Poncelet's law. For fixed velocity, it is proportional to the projectile cross-sectional area rather than to its volume. These dependences only hold in the early stages of stopping, before the projectile has been strongly fragmented. Analogies to the stopping of atomic clusters in compact matter are pointed out.

Effects of livestock grazing on flocks of seed-eating birds in the central Monte desert, Argentina

Zarco, A ;Cueto, VR ; Sagario, MC ; Marone, L ; CANADIAN JOURNAL OF ZOOLOGY ,2019 ,97 ,606 -611 .

Animal populations often decline due to habitat disturbance, but the initial response of organisms to human-induced environmental change is usually behavioral. Intra-and inter-specific interactions can restrict or facilitate access to resources, resulting in changes to individual fitness, and resource depletion may affect the frequency and strength of interactions. In birds, it is often assumed that feeding in groups increases foraging efficiency. We assessed how the reduction of seed resources provoked by cattle grazing affected different properties of seed-eating bird flocks in woodlands having the same structural characteristics but differing in seed abundance. Under lower availability of grass seeds (i.e., under grazing), flocks were smaller and less rich and birds showed a lower flocking propensity. This pattern could be explained by three non-exclusive hypotheses. Food reduction caused by grazing (i) decreases the number of seed-eating birds and concomitantly generates smaller flocks; (ii) reduces the density of nuclear species, decreasing the group cohesion in large flocks; (iii) makes large flocks less attractive by increasing individual competence for food. Our results provide evidence that cattle grazing affect the interactions of seed-eating birds and suggest the importance of understanding flocking behavior to bring about management actions.

Data mining approach based on chemical composition of grape skin for quality evaluation and traceability prediction of grapes

Canizo, BV ;Escudero, LB ; Pellerano, RG ; Wuilloud, RG ; COMPUTERS AND ELECTRONICS IN AGRICULTURE ,2019 ,162 ,514 -522 .

The knowledge of wine origin is an important aspect in winemaking industries due to the Denomination of Controlled Origin. In this work, a data mining algorithms comparison study of grape-skin samples from five regions of Mendoza, Argentina, and builds classification models capable of predicting provenance based on multi-elemental composition, were developed. Inductively coupled plasma mass spectrometry (ICP-MS) was used to determine 29 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). Four classification techniques, including multinomial logistic regression (MLR), k-nearest neighbors (k-NN), support vector machines (SVM), and random forests (RF) were assessed. The best results were achieved for SVM and RF models, with 84% and 88.9% prediction accuracy, respectively, on the 10 fold cross validation. The RF variable importance showed that Rb (rubidium) was the most relevant components for prediction.

Elucidating genomic patterns and recombination events in plant cybrid mitochondria

Garcia, LE ;Zubko, MK ; Zubko, EI ; Sanchez-Puerta, MV ; PLANT MOLECULAR BIOLOGY ,2019 ,100 ,433 -450 .

Key messageCybrid plant mitochondria undergo homologous recombination, mainly BIR, keep a single allele for each gene, and maintain exclusive sequences of each parent and a single copy of the homologous regions.AbstractThe maintenance of a dynamic equilibrium between the mitochondrial and nuclear genomes requires continuous communication and a high level of compatibility between them, so that alterations in one genetic compartment need adjustments in the other. The co-evolution of nuclear and mitochondrial genomes has been poorly studied, even though the consequences and effects of this interaction are highly relevant for human health, as well as for crop improvement programs and for genetic engineering. The mitochondria of plants represent an excellent system to understand the mechanisms of genomic rearrangements, chimeric gene formation, incompatibility between nucleus and cytoplasm, and horizontal gene transfer. We carried out detailed analyses of the mtDNA of a repeated cybrid between the solanaceae Nicotiana tabacum and Hyoscyamus niger. The mtDNA of the cybrid was intermediate between the size of theparental mtDNAs and the sum of them. Noticeably, most of the homologous sequences inherited from both parents were lost. In contrast, the majority of the sequences exclusive of a single parent were maintained. The mitochondrial gene content included a majority of N. tabacum derived genes, but also chimeric, two-parent derived, and H. niger-derived genes in a tobacco nuclear background. Any of these alterations in the gene content could be the cause of CMS in the cybrid. The parental mtDNAs interacted through 28 homologous recombination events and a single case of illegitimate recombination. Three main homologous recombination mechanisms were recognized in the cybrid mitochondria. Break induced replication (BIR) pathway was the most frequent. We propose that BIR could be one of the mechanisms responsible for the loss of the majority of the repeated regions derived from H. niger.

Multimodal neurocognitive markers of interoceptive tuning in smoked cocaine

de la Fuente, A ;Sedeno, L ; Vignaga, SS ; Ellmann, C ; Sonzogni, S ; Belluscio, L ; Garcia-Cordero, I ; Castagnaro, E ; Boano, M ; Cetkovich, M ; Torralva, T ; Canepa, ET ; Tagliazucchi, E ; Garcia, AM ; Ibanez, A ; NEUROPSYCHOPHARMACOLOGY ,2019 ,44 ,1425 -1434 .

Contemporary neurocognitive models of drug addiction have associated this condition with changes in interoception - namely, the sensing and processing of body signals that fulfill homeostatic functions relevant for the onset and maintenance of addictive behavior. However, most previous evidence is inconsistent, behaviorally unspecific, and virtually null in terms of direct electrophysiological and multimodal markers. To circumvent these limitations, we conducted the first assessment of the relation between cardiac interoception and smoked cocaine dependence (SCD) in a sample of (a) 25 participants who fulfilled criteria for dependence on such a drug, (b) 22 participants addicted to insufflated clorhidrate cocaine (only for behavioral assessment), and (c) 25 healthy controls matched by age, gender, education, and socioeconomic status. We use a validated heartbeat-detection (HBD) task and measured modulations of the heart-evoked potential (HEP) during interoceptive accuracy and interoceptive learning conditions. We complemented this behavioral and electrophysiological data with offline structural (MRI) and functional connectivity (fMRI) analysis of the main interoceptive hubs. HBD and HEP results convergently showed that SCD subjects presented ongoing psychophysiological measures of enhanced interoceptive accuracy. This pattern was associated with a structural and functional tuning of interoceptive networks (reduced volume and specialized network segregation). Taken together, our findings provide the first evidence of an association between cardiac interoception and smoked cocaine, partially supporting models that propose hyper-interoception as a key aspect of addiction. More generally, our study shows that multimodal assessments of interoception could substantially inform the clinical and neurocognitive characterization of psychophysiological and neurocognitive adaptations triggered by addiction.

Biocontrol of postharvest Alternaria decay in table grapes from Mendoza province

Stocco, AF ;Diaz, ME ; Romera, MCR ; Mercado, LA ; Rivero, ML ; Ponsone, ML ; BIOLOGICAL CONTROL ,2019 ,134 ,114 -122 .

Postharvest diseases cause considerable loss of fruit during transportation and storage. Synthetic fungicides are primarily used to control them. However, the recent trend is to shift toward safer and more eco-friendly alternatives for the control of postharvest decays. In Argentina, Alternaria genus was cited as a postharvest pathogen on table grapes for the first time during 2010-2012 seasons. The aim of this study was to identify, by morphological and molecular techniques, Alternaria spp. strains isolated from table grapes cv. Red Globe in different phenological stages of vine and postharvest storage in Mendoza province. In addition, we intended to propose an alternative postharvest management to the use of sulfur dioxide (SO2) generators (traditional method). We searched for a lower environmental impacting substitute using the yeast strain Metschnikowia pulcherrima RCM2 and chitosan coatings as possible control agents. The results showed that the pathogen was present in all the stages studied and the 100% of the strains belonged to the species-group Alternaria alternata. Besides, chitosan coatings showed to be a good alternative method to SO2 generators. This work is focus on the study of the incidence of Alternaria spp. during the phenological cycle and postharvest storage of table grapes cv. Red Globe, and also on the evaluation of alternative strategies to the use of SO2 for the control of this disease during the extended cold storage.

Genetic diversity and differentiation among provenances of Prosopis flexuosa DC (Leguminosae) in a progeny trial: Implications for arid land restoration

Bessega, C ;Cony, M ; Saidman, BO ; Aguilo, R ; Villagra, P ; Alvarez, JA ; Pometti, C ; Vilardi, JC ; FOREST ECOLOGY AND MANAGEMENT ,2019 ,443 ,59 -68 .

Ecosystem restoration has gained increasing interest to mitigate the effects of climate change, loss of biodiversity and desertification. Since the genetic composition of the reproductive material to revegetate degraded areas affects the success of restoration throughout time, information on the genetic properties of possible seed sources is essential to evaluate the risks associated to management practices. Prosopis flexuosa (Leguminosae) is an important native species in Argentina valuable from an economic and ecological point of view. Aiming to give restoration recommendations for the use of this species for rapid recuperation of the plant cover in arid regions of Monte desert, our goals were to quantify the genetic basis of phenotypic differences in height and basal diameter and the genetic differentiation of neutral markers among several provenances installed in a provenance and progeny test. Ours results suggest that the morphological variation have a significant genetic basis and differences among provenances may be explained by local adaptation. Low but significant genetic differentiation was detected by microsatellites among provenances. From our results the recommendation to provide a broad genetic basis in a restoration programme is obtaining seeds representing all genetic clusters identified, rather than all provenances. This implies avoiding sampling of more than one provenance embracing the same genetic clusters. If the priority of the programme is reaching ground cover rapidly the representation of different clusters in the source sample may be adjusted according to a tradeoff between expected gain in growth rate while keeping a broad genetic basis that insures evolutionary resilience.

Directed adaptation of synchronization levels in oscillator communities

Fengler, E ;Totz, JF ; Kaluza, P ; Engel, H ; CHAOS ,2019 ,29 ,59 -68 .

We present an adaptive control scheme that realizes desired dynamics of an oscillator network with a given number of communities by adjusting the coupling weights between oscillators accordingly. The scheme allows, for example, to simultaneously establish different pregiven synchronization levels in the particular communities as well as phase relationships between them. We apply the method in numerical simulations with all-to-all and randomly coupled networks. Moreover, we provide an experimental proof of concept validating our numerical findings in a network of optically coupled photosensitive chemical micro-oscillators. Published under license by AIP Publishing.

Thermogravimetric Study of Porous Forsterite Synthesis by Hydromagnesite and Silica Gel Chlorination

Orosco, RP ;Ojeda, MW ; Gonzalez, JA ; Barbosa, LI ; SILICON ,2019 ,11 ,1413 -1419 .

A novel pyrometallurgical process for the synthesis of porous forsterite by calcination in chlorine of a mixture containing hydromagnesite and silica gel was developed. The aim of this work was to produce porous forsterite at low temperatures and short reaction times. Effects of temperature, reaction time and chlorine on the synthesis reaction were studied. Also, the reaction mechanism involved in the process was investigated. Isothermal and non-isothermal chlorination assays were carried out in a thermogravimetric equipment designed to work in corrosive atmospheres. Reagents and products were analyzed by thermogravimetry (TG) and X-ray diffraction (XRD), scanning electron microscopy (SEM) and N-2 adsorption-desorption isotherm (BET). The results showed that forsterite was obtained at 700 degrees C with a mesoporous structure and a specific surface area of 16.8 m(2)/g. Furthermore, it was observed that the presence of chlorine favored the decomposition of hydromagnesite.

Morphological characterization and molecular phylogeny of zoonotic trematodes in the freshwater snail Asolene platae

Dellagnola, FA ;Montes, MM ; Martorelli, SR ; Vega, IA ; PARASITOLOGY ,2019 ,146 ,839 -848 .

In the context of a broader program dealing with the symbiotic associations of apple snails, we sampled three species that coexist in Lake Regatas (Palermo, Buenos Aires, Argentina). The population of Asolene platae, (but not those of Pomacea canaliculata and Pomacea scalaris) showed trematode larvae (echinocercariae and xiphidiocercariae) in haemocoelic spaces and connective tissue of the digestive gland. The echinocercariae resembled those of the genus Echinochasmus, but lacked sensory hairs on their body and tail; whereas xiphidiocercariae were similar to the xiphidiocercariae armatae belonging to the Opisthoglyphe type. The phylogenetical positions of these trematodes were inferred by the 28S rRNA, ITS1 and mtCOXI gene sequences. The 28S rRNA gene linked the echinocercarial sequences with the polyphyletic genus Echinochasmus (Echinochasmidae), while the xiphidiocercarial sequences were linked with the genus Phaneropsolus (Phaneropsolidae). The molecular markers used were able to distinguish two cryptic molecular entities of the single echinocercarial morphotype. Although ITS1 and mtCOXI did not allow resolving phylogeny beyond the family level because of the scarce number of sequences in the molecular databases, both cercariae (echinocercariae and xiphidiocercariae) could be distinguished by the Internal Transcribed Spacer 1 amplicon size. This is the first correlative morphological and molecular study of zoonotic trematodes in Neotropical ampullariids.

Ant community patterns in highly fragmented Chaco forests of central Argentina

Pereyra, M ;Pol, RG ; Galetto, L ; AUSTRAL ECOLOGY ,2019 ,44 ,668 -679 .

The Chaco is the largest dry forest biome in South America and one of the regions most threatened by agricultural intensification. As a consequence, in several areas Chaco forests persist as forest remnants of different sizes embedded in an agricultural matrix. Ants are social insects that have key roles in ecosystem functioning, and the effects of this ongoing land use change process on ant communities are little known for this region. In the present study, we assessed the consequences of land use replacement by monocultures and forest fragmentation on ant communities. Particularly, we assessed whether patch size, patch isolation and edge effect affect species richness and composition of ground-dwelling ants in fragmented landscapes of Chaco forests. We collected ants by combining hand collecting and pitfall traps in 17 forest fragments and the surrounding matrix from two sites in Cordoba, Argentina. Patch size and patch isolation had no effect on ant richness; however, patch isolation and, to a lesser extent, patch size altered ant species composition. The ant community was not affected by edge but it was negatively affected by the crop matrix, which reduced richness and altered species composition. These results indicate that monoculture matrices severely affect ant communities in the Chaco forests, and that the effects of other indicators of habitat fragmentation (patch size and edge effect) are subtler and less relevant. In the present context of land use change, even small fragments could have an important value for the conservation of ant diversity.


Marquez, O ;Simondi, S ; Vargas, JA ; REVISTA DE LA UNION MATEMATICA ARGENTINA ,2019 ,60 ,45 -59 .

For a connected, noncompact simple matrix Lie group G so that a maximal compact subgroup K has a three dimensional simple ideal, in this note we analyze the admissibility of the restriction of irreducible square integrable representations for the ambient group when they are restricted to certain subgroups that contain the three dimensional ideal. In this setting we provide a formula for the multiplicity of the irreducible factors. Also, for general G such that G/K is an Hermitian G-manifold we give a necessary and sufficient condition so that an arbitrary square integrable representation of the ambient group is admissible over the semisimple factor of K.

Environmental degradation and opportunities for riparian rehabilitation in a highly urbanized watershed: the Matanza-Riachuelo in Buenos Aires, Argentina

Guida-Johnson, B ;Zuleta, GA ; WETLANDS ECOLOGY AND MANAGEMENT ,2019 ,27 ,243 -256 .

The growth of human societies worldwide has been associated with the degradation of natural resources; in particular, freshwater ecosystems are among the most seriously threatened. Riparian restoration has received much attention due to the importance of ecological functions and ecosystem services sustained by watercourses. The objective of this paper was to assess the environmental quality of riversides in a highly urbanized watershed in the Buenos Aires metropolitan area (Argentina) in order to identify rehabilitation opportunities. We conducted a stratified random sampling of 82 sites where we recorded 33 variables regarding geomorphologic traits, vegetation attributes and anthropogenic impacts. Pristine riparian habitats are almost completely extirpated throughout the watershed and most of the streams sampled showed signs of degradation related to multiple threats. We detected a degradation pattern that follows the urban-rural gradient occurring in the watershed which enabled the definition of four types of riversides. In order to identify potential river rehabilitation alternatives in accordance with each degradation driver detected, we performed a systematic review of the literature. We identified the fluvial rehabilitation techniques implemented and we grouped them into four types of measures: passive restoration, active abiotic techniques, active biotic techniques and active social techniques. We also recognized the reported social, ecological, economic and/or political constraints which were encountered in those experiences. All possible dimensions of the potential constraints should be recognized during the planning stage of rehabilitation and then properly addressed before and during the implementation of measures in order to make the interventions successful.

A new ornithopod dinosaur (Dinosauria: Ornithischia) from the Late Cretaceous of central Patagonia

Ibiricu, LM ;Casal, GA ; Martinez, RD ; Luna, M ; Canale, JI ; Alvarez, BN ; Riga, BG ; CRETACEOUS RESEARCH ,2019 ,98 ,276 -291 .

A new ornithopod dinosaur, the medium-sized Sektensaurus sanjuanboscoi gen. et sp nov. from the Coniacian-Maastricthian strata of the Lago Colhue-Huapi Formation, Golfo San Jorge Basin, Patagonia, is here described. The specimen consists of disarticulated postcranial bones belonging to a single individual. It is diagnosed by an unique association of five autapomorphies on the dorsal and sacral vertebrae and the humerus. A cladistics analysis indicates that Sektensaurus was an iguanodontian ornithopod which inhabited Patagonia during the Late Cretaceous. Likewise, Sektensaurus is the first nonhadrosaurid, probably elasmarian, ornithopod recorded from the uppermost Cretaceous of central Patagonia. In a broad context, this discovery increases the anatomical knowledge of ornithopods and adds new data on the composition of dinosaur faunas that lived in Patagonia close to the Antarctica, at the end of the Cretaceous. (C) 2019 Elsevier Ltd. All rights reserved.

Determination of As in honey samples by magnetic ionic liquid-based dispersive liquid-liquid microextraction and electrothermal atomic absorption spectrometry

Fiorentini, EF ;Canizo, BV ; Wuilloud, RG ; TALANTA ,2019 ,198 ,146 -153 .

A dispersive liquid-liquid microextraction (DLLME) method was developed based on the application of a magnetic ionic liquid (MIL) used as extractant phase for trace As determination in honey samples by electrothermal atomic absorption spectrometry (ETAAS). The procedure was simple, efficient and did not require a centrifugation stage. The As(III) species was preconcentrated by chelation with ammonium diethyldithiophosphate under acidic conditions at 3 mol L-1 HCl, followed by the extraction of the chelated analyte 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 simply by a magnet. The collected aliquot of the MIL phase was injected directly into the graphite furnace of ETAAS for As determination. Under optimal experimental conditions, an extraction efficiency of 99% and a sensitivity enhancement factor of 110 were obtained. The limit of detection was 12 ng L-1 As and the relative standard deviation 3.9% (at 1 mu g L-1 As and n = 10), calculated from the peak height of the absorbance signals. The linear range obtained was 0.02-5.0 mu g L-1. 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 determination of As in honeys.

Driven Liouville-von Neumann Equation for Quantum Transport and Multiple-Probe Green's Functions Published as part of The Journal of Physical Chemistry virtual special issue "Abraham Nitzan Festschrift"

Ramirez, F ;Dundas, D ; Sanchez, CG ; Scherlis, DA ; Todorov, TN ; JOURNAL OF PHYSICAL CHEMISTRY C ,2019 ,123 ,12542 -12555 .

The so-called driven Liouville von Neumann equation is a dynamical formulation to simulate a voltage bias across a molecular system and to model a time-dependent current in a grand-canonical framework. This approach introduces a damping term in the equation of motion that drives the charge to a reference, out of equilibrium density. Originally proposed by Horsfield and coworkers, further work on this scheme has led to different coexisting versions of this equation. On the other hand, the multiple-probe scheme devised by Todorov and collaborators, known as the hairy-probes method, is a formal treatment based on Green's functions that allows the electrochemical potentials in two regions of an open quantum system to be fixed. In this article, the equations of motion of the hairy-probes formalism are rewritten to show that, under certain conditions, they can assume the same algebraic structure as the driven Liouville-von Neumann equation in the form proposed by Morzan et al. (J. Chem. Phys. 2017, 146, 044110). In this way, a new formal ground is provided for the latter, identifying the origin of every term. The performances of the different methods are explored using tight-binding time-dependent simulations in three trial structures, designated as ballistic, disordered, and resonant models. In the context of first-principles Hamiltonians, the driven Liouville von Neumann approach is of special interest, because it does not require the calculation of Green's functions. Hence, the effects of replacing the reference density based on the Green's function by one obtained from an applied field are investigated, to gain a deeper understanding of the limitations and the range of applicability of the driven Liouville-von Neumann equation.

Plasmon-induced hot-carrier generation differences in gold and silver nanoclusters

Douglas-Gallardo, OA ;Berdakin, M ; Frauenheim, T ; Sanchez, CG ; NANOSCALE ,2019 ,11 ,8604 -8615 .

In the last thirty years, the study of plasmonic properties of noble metal nanostructures has become a very dynamic research area. The design and manipulation of matter in the nanometric scale demands a deep understanding of the underlying physico-chemical processes that operate in this size regimen. Here, a fully atomistic study of the spectroscopic and photodynamic properties of different icosahedral silver and gold nanoclusters has been carried out by using a Time-Dependent Density Functional Tight-Binding (TD-DFTB) model. The optical absorption spectra of different icosahedral silver and gold nanoclusters of diameters between 1 and 4 nanometers have been simulated. Furthermore, the energy absorption process has been quantified by means of calculating a fully quantum absorption cross-section using the information contained in the reduced single-electron density matrix. This approach allows us take into account the quantum confinement effects dominating in this size regime. Likewise, the plasmon-induced hot-carrier generation process under laser illumination has been explored from a fully dynamical perspective. We have found noticeable differences in the energy absorption mechanisms and the plasmon-induced hot-carrier generation process in both metals which can be explained by their respective electronic structures. These differences can be attributed to the existence of ultra-fast electronic dissipation channels in gold nanoclusters that are absent in silver nanoclusters. To the best of our knowledge, this is the first report that addresses this topic from a real time fully atomistic time-dependent approach.


Pinna, EG ;Martinez, AA ; Tunez, FM ; Drajlin, DS ; Rodriguez, MH ; REVISTA MEXICANA DE INGENIERIA QUIMICA ,2019 ,18 ,441 -449 .

This work shows the results of a comparative hydrometallurgical study of LiCoO2 leaching, obtained from the cathodes of spent lithium-ion batteries (LIBs), with HF and HF/H2O2. The operational parameters researched were H2O2 and HF concentrations, solid-liquid ratio, stirring speed, temperature and reaction time. The experimental results indicated that the best working conditions, with dissolution values close to 100%, were 348 K, 330 rpm, 30 min, 8 g/L, HF 0.6 M and H2O2 0.7 M. Thermodynamic study of the dissociation of HF in aqueous solution and E-H-pH diagrams for Li-H2O, Co-H2O and Li-Co-F-H2O systems were performed. The results showed the feasibility of extracting and recovering metals contained in the sample.

Clinanthus microstephium, an Amaryllidaceae Species with Cholinesterase Inhibitor Alkaloids: Structure-Activity Analysis of Haemanthamine Skeleton Derivatives

Adessi, TG ;Borioni, JL ; Pigni, NB ; Bastida, J ; Cavallaro, V ; Murray, AP ; Puiatti, M ; Oberti, JC ; Leiva, S ; Nicotra, VE ; Garcia, ME ; CHEMISTRY & BIODIVERSITY ,2019 ,16 ,441 -449 .

Plants of the Amaryllidaceae family are well-known (not only) for their ornamental value but also for the alkaloids that they produce. In this report, the first phytochemical study of Clinanthus genus was carried out. The chemical composition of alkaloid fractions from Clinanthus microstephium was analyzed by GC/MS and NMR. Seven known compounds belonging to three structural types of Amaryllidaceae alkaloids were identified. An epimeric mixture of a haemanthamine-type compound (6-hydroxymaritidine) was tested as an inhibitor against acetyl- and butyrylcholinesterase enzymes (AChE and BChE, respectively), two enzymes relevant in the treatment of Alzheimer's disease, with good results. Structure-activity relationships through molecular docking studies with this alkaloid and other structurally related compounds were discussed.

Separation and preconcentration of inorganic Se species in tap and natural waters using unfunctionalized nanosilica as sorption material in dispersive micro-solid phase extraction

Llaver, M ;Wuilloud, RG ; MICROCHEMICAL JOURNAL ,2019 ,146 ,763 -770 .

A highly sensitive and selective method based on dispersive micro-solid phase extraction (D-mu-SPE) technique was developed for the determination of inorganic Se species. A very simple and fast preconcentration procedure involving the use of pure nanosilica for the extraction of Se(IV) complexed with ammonium pyrrolidine dithiocarbamate (APDC) was applied. Elution of the retained Se(IV) species from nanosilica was achieved with ethyl acetate followed by electrothermal atomic absorption spectrometry determination. For speciation analysis, Se(VI) was selectively quantified based on the difference between the concentrations of total inorganic Se and Se (IV) after a pre-reduction step. The interaction between the analyte and the extractant was characterized by FT-IR and an adsorption isotherm study. A 90% extraction efficiency was achieved after optimization of all factors concerning the extraction and elution steps, such as pH, ionic strength and type of chelating agent. Optimized conditions included pH = 2.0, 4.9 mu mol L-1 APDC and the use of 1 mg nanosilica as adsorbent. A limit of detection of 1.4 ng L-1, a relative standard deviation of 4.8% and a 90-fold enhancement factor were obtained with 10 mL of sample. The developed method was finally applied to water samples from different origins and compositions, including rain, tap, underground, and sea.

Impact of double inoculation with Bradyrhizobium japonicum E109 and Azospirillum brasilense Az39 on soybean plants grown under arsenic stress

Armendariz, AL ;Talano, MA ; Nicotra, MFO ; Escudero, L ; Breser, ML ; Porporatto, C ; Agostini, E ; PLANT PHYSIOLOGY AND BIOCHEMISTRY ,2019 ,138 ,26 -35 .

Inoculation practice with plant growth-promoting bacteria (PGPB) has been proposed as a good biotechnological tool to enhance plant performance and alleviate heavy metal/metalloid stress. Soybean is often cultivated in soil with high arsenic (As) content or irrigated with As-contaminated groundwater, which causes deleterious effects on its growth and yield, even when it was inoculated with rhizobium. Thus, the effect of double inoculation with known PGPB strains, Bradyrhizobiwn japonicum E109 and Azospirillwn brasilense Az39 was evaluated in plants grown in pots under controlled conditions and treated with As. First, the viability of these co-cultivated bacteria was assayed using a flow cytometry analysis using SYTO9 and propidium iodide (PI) dyes. This was performed in vitro to evaluate the bacterial population dynamic under 25 mu M AsV and AsIII treatment. A synergistic effect was observed when bacteria were co-cultured, since mortality diminished, compared to each growing alone. Indole acetic acid (IAA) produced by A. brasilense Az39 would be one of the main components involved in B. japonicum E109 mortality reduction, mainly under MITI treatment. Regarding in vivo assays, under As stress, plant growth improvement, nodule number and N content increase were observed in double inoculated plants. Furthermore, double inoculation strategy reduced As translocation to aerial parts thus improving As phytostabilization potential of soybean plants. These results suggest that double inoculation with B. japonicum E109 and A. brasilense Az39 could be a safe and advantageous practice to improve growth and yield of soybean exposed to As, accompanied by an important metalloid phytostabilization.

Chemometric-based, 3D chemical-architectural model of Odontopteris cantabrica Wagner (Medullosales, Pennsylvanian, Canada): Implications for natural classification and taxonomy

Zodrow, EL ;D'Angelo, JA ; INTERNATIONAL JOURNAL OF COAL GEOLOGY ,2019 ,207 ,12 -25 .

The largest known (365 mm-long) specimen of Odontopteris cantabrica Wagner from the Late Pennsylvanian Sydney Coalfield in Canada was re-examined as part of the on-going research project "Chemistry and Architecture of Carboniferous Seed Ferns" to refine the 3D plant-reconstruction concept further in the framework of natural classification. The micromorphology and functional-group content and distribution of O. cantabrica are investigated by methods of Fourier transform infrared spectroscopy. Results demonstrate that the specimen is naturally macerated, showing little or no cellular features. Two types of stomatal structures occurred, however: anomocytic on abaxial pinnule surfaces, and cyclocytic amphistomatically on the rachises. Hence, the frond was entirely photosynthetic. Chemometric analysis of the infrared data resulted not only in a 3D chemical model, but also confirmed the hypothesis of the chemical-architectural relationship in extinct medullosalean fronds. Further demonstrated is the predictive power of chemometrics for reconstruction, hence frond interpretation, in the absence of certain frond parts. Inferred from the collective data is a basally bifurcate and larger frond, of larger size than previously believed, which could indicate a self-supporting (arborescent) or semi self-supporting habit for the O. cantabrica plant. The concept of natural classification for plant fossils, underpinned by a holistic data approach, is proposed based on data from Neuropteris ovata var. simonii, Alethopteris ambigua, and O. cantabrica.

Intratumor heterogeneity index of breast carcinomas based on DNA methylation profiles

Campoy, EM ;Branham, MT ; Mayorga, LS ; Roque, M ; BMC CANCER ,2019 ,19 ,12 -25 .

Background: Cancer cells evolve and constitute heterogeneous populations that fluctuate in space and time and are subjected to selection generating intratumor heterogeneity. This phenomenon is determined by the acquisition of genetic/epigenetic alterations and their selection over time which has clinical implications on drug resistance.

Light-use efficiency and energy partitioning in rice is cultivar dependent

Quero, G ;Bonnecarrere, V ; Fernandez, S ; Silva, P ; Simondi, S ; Borsani, O ; PHOTOSYNTHESIS RESEARCH ,2019 ,140 ,51 -63 .

One of the main limitations of rice yield in regions of high productive performance is the light-use efficiency (LUE). LUE can be determined at the whole-plant level or at the photosynthetic apparatus level (quantum yield). Both vary according to the intensity and spectral quality of light. The aim of this study was to analyze the cultivar dependence regarding LUE at the plant level and quantum yield using four rice cultivars and four light environments. To achieve this, two in-house Light Systems were developed: Light System I which generates white light environments (spectral quality of 400-700nm band) and Light System II which generates a blue-red light environment (spectral quality of 400-500nm and 600-700nm bands). Light environment conditioned the LUE and quantum yield in PSII of all evaluated cultivars. In white environments, LUE decreased when light intensity duplicated, while in blue-red environments no differences on LUE were observed. Energy partition in PSII was determined by the quantum yield of three de-excitation processes using chlorophyll fluorescence parameters. For this purpose, a quenching analysis followed by a relaxation analysis was performed. The damage of PSII was only increased by low levels of energy in white environments, leading to a decrease in photochemical processes due to the closure of the reaction centers. In conclusion, all rice cultivars evaluated in this study were sensible to low levels of radiation, but the response was cultivar dependent. There was not a clear genotypic relation between LUE and quantum yield.

A combinatorial characterization of Hurewicz cofibrations between finite topological spaces

Cianci, N ;Ottina, M ; TOPOLOGY AND ITS APPLICATIONS ,2019 ,256 ,235 -247 .

We characterize the Hurewicz cofibrations between finite topological spaces, that is, the continuous functions between finite topological spaces that have the homotopy extension property with respect to all topological spaces. In particular, we show that cofibrations between connected non-empty finite topological spaces are homotopy equivalences.

Mitochondrial stress triggers a pro-survival response through epigenetic modifications of nuclear DNA

Mayorga, L ;Salassa, BN ; Marzese, DM ; Loos, MA ; Eiroa, HD ; Lubieniecki, F ; Samartino, CG ; Romano, PS ; Roque, M ; CELLULAR AND MOLECULAR LIFE SCIENCES ,2019 ,76 ,1397 -1417 .

Mitochondrial dysfunction represents an important cellular stressor and when intense and persistent cells must unleash an adaptive response to prevent their extinction. Furthermore, mitochondria can induce nuclear transcriptional changes and DNA methylation can modulate cellular responses to stress. We hypothesized that mitochondrial dysfunction could trigger an epigenetically mediated adaptive response through a distinct DNA methylation patterning. We studied cellular stress responses (i.e., apoptosis and autophagy) in mitochondrial dysfunction models. In addition, we explored nuclear DNA methylation in response to this stressor and its relevance in cell survival. Experiments in cultured human myoblasts revealed that intense mitochondrial dysfunction triggered a methylation-dependent pro-survival response. Assays done on mitochondrial disease patient tissues showed increased autophagy and enhanced DNA methylation of tumor suppressor genes and pathways involved in cell survival regulation. In conclusion, mitochondrial dysfunction leads to a pro-survival adaptive state that seems to be triggered by the differential methylation of nuclear genes.

Grab recruitment by Rab27A-Rabphilin3a triggers Rab3A activation in human sperm exocytosis

Quevedo, MF ;Bustos, MA ; Masone, D ; Roggero, CM ; Bustos, DM ; Tomes, CN ; BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH ,2019 ,1866 ,612 -622 .

Sperm must undergo the regulated exocytosis of its dense core granule (the acrosome reaction, AR) to fertilize the egg. We have previously described that Rabs3 and 27 are organized in a RabGEF cascade within the signaling pathway elicited by exocytosis stimuli in human sperm. Here, we report the identity and the role of two molecules that link these secretory Rabs in the RabGEF cascade: Rabphilin3a and GRAB. Like Rab3 and Rab27, GRAB and Rabphilin3a are present, localize to the acrosomal region and are required for calcium-triggered exocytosis in human sperm. Sequestration of either protein with specific antibodies introduced into streptolysin O-permeabilized sperm impairs the activation of Rab3 in the acrosomal region elicited by calcium, but not that of Rab27. Biochemical and functional assays indicate that Rabphilin3a behaves as a Rab27 effector during the AR and that GRAB exhibits GEF activity toward Rab3A. Recombinant, active Rab27A pulls down Rabphilin3a and GRAB from human sperm extracts. Conversely, immobilized Rabphilin3a recruits Rab27 and GRAB; the latter promotes Rab3A activation. The enzymatic activity of GRAB toward Rab3A was also suggested by in silico and in vitro assays with purified proteins. In summary, we describe here a signaling module where Rab27A-GTP interacts with Rabphilin3a, which in turn recruits a guanine nucleotide-exchange activity toward Rab3A. This is the first description of the interaction of Rabphilin3a with a GEF. Because the machinery that drives exocytosis is highly conserved, it is tempting to hypothesize that the RabGEF cascade unveiled here might be part of the molecular mechanisms that drive exocytosis in other secretory systems.

Bouncing window for colliding nanoparticles: Role of dislocation generation

Nietiadi, ML ;Millan, EN ; Bringa, EM ; Urbassek, HM ; PHYSICAL REVIEW E ,2019 ,99 ,612 -622 .

Available macroscopic theories-such as the Johnson-Kendall-Roberts (JKR) model-predict spherical particles to stick to each other at small collision velocities v; above the bouncing velocity, v(b), they bounce. We study the details of the bouncing threshold using molecular dynamics simulation for crystalline nanoparticles where atoms interact via the Lennard-Jones potential. We show that the bouncing velocity strongly depends on the nanoparticle orientation during collision; for some orientations, nanoparticles stick at all velocities. The dependence of bouncing on orientation is caused by energy dissipation during dislocation activity. The bouncing velocity decreases with increasing nanoparticle radius in reasonable agreement with JKR theory. For orientations for which bouncing exists, nanoparticles stick again at a higher velocity, the fusion velocity, v(f), such that bouncing only occurs in a finite range of velocities-the bouncing window. The fusion velocity is rather independent of the nanoparticle radius.

Pilot testing of a bioremediation system for water and soils contaminated with heavy metals: vegetable depuration module

Scotti, A ;Silvani, VA ; Cerioni, J ; Visciglia, M ; Benavidez, M ; Godeas, A ; INTERNATIONAL JOURNAL OF PHYTOREMEDIATION ,2019 ,21 ,899 -907 .

We present a novel constructed wetland called a vegetable depuration module (VDM) as a pilot test of a bioremediation system (BS) for decontaminating water and soil polluted with heavy metals. The VDM consisted of a pool filled with stones of different granulometry and a substrate top layer composed of a mixture of soil and volcanic ash (50:50, v/v) supplemented with 350 ppm Zn. The BS of sunflower plants colonized by the arbuscular mycorrhizal fungus Rhizophagus intraradices was planted in the VDM. Initially, the substrate registered high concentrations of Zn, Cr, Mn, Cu, and Sr, and had Eh > +500 mV and pH 8.4. Irrigation with a Cu solution by vertical flow was carried out. After 3 months, bioaccumulation factors ranged from 1.00 to 8.90, and translocation rates were >1 for Sr and Cu. Total metals extracted by the BS and percolation were 31%, 34%, 50%, 45%, and 57% for Zn, Cu, Mn, Cr, and Sr, respectively. Only the BS was capable of extracting 94% of Cu and 38% of Zn. VDM allowed us to calibrate the extractive performance of the studied elements in BS. This biotechnological development holds great potential for phytoremediation of polluted areas.

Insights into mechanochemical reactions at the molecular level: simulated indentations of aspirin and meloxicam crystals

Ferguson, M ;Moyano, MS ; Tribello, GA ; Crawford, DE ; Bringa, EM ; James, SL ; Kohanoff, J ; Del Popolo, MG ; CHEMICAL SCIENCE ,2019 ,10 ,2924 -2929 .

Although solvent-free mechanochemical synthesis continues to gain ever greater importance, the molecular scale processes that occur during such reactions remain largely uncharacterised. Here, we apply computational modelling to indentations between particles of crystals of aspirin and meloxicam under a variety of conditions to mimic the early stages of their mechanochemical cocrystallisation reaction. The study also extends to the effects of the presence of small amounts of solvent. It is found that, despite the solid crystalline nature of the reactants and the presence of little or no solvent, mixing occurs readily at the molecular level even during relatively low-energy collisions. When indented crystals are subsequently drawn apart, a connective neck formed by a mixture of the reactant molecules is observed, suggesting plastic-like behaviour of the reacting materials. Overall the work reveals some striking new insights including (i) relatively facile mixing of crystals under solvent-free conditions, (ii) no appreciable local temperature increases, (iii) localised amorphisation at the contact region and neck of the reacting crystals, and (iv) small amounts of solvent have relatively little effect during this early stage of the reaction, suggesting that their accelerating effect on the reaction may be exerted at later stages.

Spatiotemporal distribution of organotin compounds in the coastal water of the Bahia Blanca estuary (Argentina)

Quintas, PY ;Alvarez, MB ; Arias, AH ; Garrido, M ; Marcovecchio, JE ; ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH ,2019 ,26 ,7601 -7613 .

Several areas within the Bahia Blanca estuary (BBE), with different maritime traffic intensity, were studied in order to confirm the presence and assess the distribution of tributyltin (TBT), dibutyltin (DBT), and monobutyltin (MBT) in the water column. The organotin compounds (OTCs) were determined in the water samplestaken in summer, autumn, winter, and spring of 2014by gas chromatography coupled to mass spectrometry after liquid-liquid extraction with hexane. The incidence of TBT throughout the whole sampling period indicated a continuous presence of this compound to the study area. However, in accordance with the butyltin degradation index (BDI), TBT was not recently introduced in the BBE. Furthermore, the average TBT levels exceeded the international guideline established by the Oslo-Paris commission (0.62 ng Sn L-1). As a result, certain biological effects could be expected to occur in sensitive species such as mussels. While DBT were below the detection limit in the 75% of the samples analyzed, MBT was detected in all the samples and no significant differences were found among the concentrations measured in the different seasons (Kruskal-Wallis test, p > 0.05). In addition, no correlations were found among the OTCs levels and the evaluated physiochemical parameters (Spearman coefficient, p > 0.05).

Recent advances on elemental biosorption

Escudero, LB ;Quintas, PY ; Wuilloud, RG ; Dotto, GL ; ENVIRONMENTAL CHEMISTRY LETTERS ,2019 ,17 ,409 -427 .

Industrial activities play a relevant role in environmental pollution since their wastes contain high concentrations of toxic elements that can add significant contamination to natural water and other water sources if no decontamination is previously applied. As toxic metals and metalloids are not biodegradable and tend to accumulate in living organisms, it is necessary to treat the contaminated industrial wastewaters prior to their discharge into the water bodies. There are different remediation techniques that have been developed to solve elemental pollution, but biosorption has arisen as a promising cleanup and low-cost biotechnology. Biosorption is governed by a variety of mechanisms including chemical binding, ion exchange, physisorption, precipitation, and oxide reduction. This review presents applications of biosorbents for metals and metalloids removal. Biomaterials including bacteria, fungi, algae, plant derivatives, agricultural wastes, and chitin-chitosan-based materials are considered. Also, bio-nano-hybrid materials, which have superlative sorption properties due to their high surface area coming from the nanomaterials structures and multifunctional capacity incorporated from the several types of chemical groups of biomaterials, are discussed. High metal removal percentages as high as 70-100% can be found in most works reported in the literature, which demonstrates the excellent performance obtained with biosorbents. These, as well as other important aspects linked to biosorption, are fully covered in the present review.

Chaos in wavy-stratified fluid-fluid flow

Vaidheeswaran, A ;Clausse, A ; Fullmer, WD ; Marino, P ; de Bertodano, ML ; CHAOS ,2019 ,29 ,409 -427 .

We perform a nonlinear analysis of a fluid-fluid wavy-stratified flow using a simplified two-fluid model (TFM), i.e., the fixed-flux model (FFM), which is an adaptation of the shallow water theory for the two-layer problem. Linear analysis using the perturbation method illustrates the short-wave physics leading to the Kelvin-Helmholtz instability (KHI). The interface dynamics are chaotic, and analysis beyond the onset of instability is required to understand the nonlinear evolution of waves. The two-equation FFM solver based on a higher-order spatiotemporal finite difference scheme is used in the current simulations. The solution methodology is verified, and the results are compared with the measurements from a laboratory-scale experiment. The finite-time Lyapunov exponent (FTLE) based on simulations is comparable and slightly higher than the autocorrelation function decay rate, consistent with previous findings. Furthermore, the FTLE is observed to be a strong function of the angle of inclination, while the root mean square of the interface height exhibits a square-root dependence. It is demonstrated that this simple 1-D FFM captures the essential chaotic features of the interface dynamics. This study also adds to a growing body of work indicating that a TFM with appropriate short wavelength physics is well-behaved and chaotic beyond the KHI. Published under license by AIP Publishing.

Mechanisms of Iodide-Triiodide Exchange Reactions in Ionic Liquids: A Reactive Molecular-Dynamics Exploration

Byrne, A ;Bringa, EM ; Del Popolo, MG ; Kohanoff, JJ ; Galassi, V ; English, NJ ; INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES ,2019 ,20 ,409 -427 .

Efficient charge transport has been observed in iodine-doped, iodide-based room-temperature ionic liquids, yielding high ionic conductivity. To elucidate preferred mechanistic pathways for the iodide exchange reactions, we have performed 10 ns reactive molecular-dynamics calculations in the liquid state for 1-butyl-3-methylimidazolium iodide ([BMIM][I]) at 450 to 750 K. Energy-barrier distributions for the iodine-swapping process were determined as a function of temperature, employing a charge-reassignment scheme drawn in part from electronic-structure calculations. Bond-exchange events were observed with rate-determining energy barriers ranging from similar to 0.19 to 0.23 +/- 0.06 eV at 750 and 450 K, respectively, with an approximately Arrhenius temperature dependence for iodine self-diffusivity and reaction kinetics, although diffusion dominates/limits the bond-exchange events. This charge transfer is not dissimilar in energetics to those in solid-state superionic conductors.

Differential effects of hypo- and hyperthyroidism on remodeling of contacts between neurons expressing the neuropeptide EI and tyrosine hydroxylase in hypothalamic areas of the male rat

Ayala, C ;Pennacchio, GE ; Soaje, M ; Bittencourt, JC ; Celis, ME ; Jahn, GA ; Valdez, SR ; Seltzer, AM ; PEPTIDES ,2019 ,113 ,1 -10 .

The Neuropeptide EI (NEI, glutamic acid- isoleucine amide) participates in neuroendocrine function. Previously we demonstrated that NEI concentration is regulated by thyroid hormones in discrete hypothalamic areas in rats. We observed that the thyroid status affects the dopaminergic regulation of the pituitary hormones. In this study we explored possible interactions between NEI and tyrosine hydroxylase (TH) containing elements in selected hypothalamic areas of male rats. Neuronal somas, terminals and boutons were assessed by confocal microscopy, in hypo- and hyperthyroid animals. We observed a remodeling of the contacts between the TH and NEI immunoreactive elements in the incerto-hypothalamic area (IHy, also known as rostromedial zona incerta) according to thyroid function. However, in the dorsolateral zone of the peduncular part of the lateral hypothalamus (DL-PLH) the thyroid hormones affect the dendritic trees of the neurons without perturbing the overall NEI/TH contacts. Also, we demonstrated that TRH Receptor 1 (TRH-R1) is colocalized in NEI immunoreactive neurons in the peduncular part of the lateral hypothalamus (PLH) and NEI precursor mRNA expression increased by hypothyroidism indicating that NEI neurons are responsive to the feedback mechanisms of the Hypothalamic Pituitary-Thyroid Axis (HPT). In conclusion, the hypothyroid status seems to increase the interactions between the NEI neurons and the dopaminergic pathways while hyperthyroidism either decreases or displays no effects. Altogether these observations support the participation of the IHy and PLH NEI as a modulating component of the HPT suggesting that altered neuroendocrine, behavioral and cognitive dysfunctions induced by dysthyroidism could be in part mediated by NEI.

Preliminary studies about the role of physicochemical parameters on the organotin compound dynamic in a South American estuary (Bahia Blanca, Argentina)

Quintas, PY ;Fernandez, EM ; Spetter, CV ; Arias, AH ; Garrido, M ; Marcovecchio, JE ; ENVIRONMENTAL MONITORING AND ASSESSMENT ,2019 ,191 ,1 -10 .

This work provides a preliminary study of the destination, mobility, and availability of tributyltin (TBT), dibutyltin (DBT), and monobutyltin (MBT) in contaminated sediments and water column within Puerto Rosales Port, located in the middle zone of the Bahia Blanca Estuary (Argentina). Therefore, this study presents the first comprehensive results of the role of several physicochemical parameters (temperature, pH, Eh, salinity, turbidity, organic matter, chlorophyll, and macronutrients) in behavior of organotin compounds (OTCs) in a marine-coastal ecosystem. The samples were collected seasonally in May, August, and November during 2014. Levels of OTCs were determined in sediments and water column samples by means of gas chromatography-mass spectrometry analysis. Degradation index analyses suggested not recent inputs of TBT at the area of study. However, results submitted a continuous input of TBT into the column water; further, its distribution and degradation pattern were shown to be influenced by salinity, turbidity, particulate organic matter, chlorophyll, and nitrates. These last two parameters, chlorophyll and nitrates, also were very important for sediment samples. Chlorophyll together with high temperatures recorded in the surface sediments triggers biodegradation process of TBT and DBT resulting in high MBT levels while nitrates seemed to promote debutylation process. Furthermore, pH appeared to influence drastically the adsorption/desorption activity of TBT and DBT in sediment. Finally, the Eh obtained suggested a degradation of TBT thanks to the presence of Fe (III) in this compartment. In addition, in fact, the results outlined a possible MBT additional input that contributes to the pollution observed in the study area.

Genome-scale transfer of mitochondrial DNA from legume hosts to the holoparasite Lophophytum mirabile (Balanophoraceae)

Sanchez-Puerta, MV ;Edera, A ; Gandini, CL ; Williams, AV ; Howell, KA ; Nevill, PG ; Small, I ; MOLECULAR PHYLOGENETICS AND EVOLUTION ,2019 ,132 ,243 -250 .

Angiosperm mitochondrial horizontal gene transfer (HGT) has been widely reported during the past decades. With a few exceptions, foreign sequences are mitochondrial genes or intronic regions from other plants, indicating that HGT has played a major role in shaping mitochondrial genome evolution. Host-parasite relationships are a valuable system to study this phenomenon due to the high frequency of HGT. In particular, the interaction between mimosoid legumes and holoparasites of the genus Lophophytum represents an outstanding opportunity to discern HGT events. The mitochondrial genome of the holoparasite L. mirabile has remarkable properties, the most extraordinary of which is the presence of 34 out of 43 mitochondrial protein genes acquired from its legume host, with the stunning replacement of up to 26 native homologs. However, the origin of the intergenic sequences that represent the majority (> 90%) of the L. mirabile mtDNA remains largely unknown. The lack of mitochondrial sequences available from the donor angiosperm lineage (mimosoid legumes) precluded a large-scale evolutionary study. We sequenced and assembled the mitochondrial genome of the mimosoid Acacia ligulata and performed genome wide comparisons with L. mirabile. The A. ligulata mitochondrial genome is almost 700 kb in size, encoding 60 genes. About 60% of the L. mirabile mtDNA had greatest affinity to members of the family Fabaceae (similar to 49% to mimosoids in particular) with an average sequence identity of similar to 96%, including genes but mostly intergenic regions. These findings strengthen the mitochondrial fusion compatibility model for angiosperm mitochondrion-to-mitochondrion HGT.

Aging and retinoid X receptor agonists on masculinization of female Pomacea canaliculata, with a critical appraisal of imposex evaluation in the Ampullariidae

Giraud-Billoud, M ;Castro-Vazquez, A ; ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY ,2019 ,169 ,573 -582 .

Ampullariidae are unique among gastropods in that females normally show a primordium of the copulatory apparatus (CApp). The aims of this study were (a) to quantitatively evaluate the development and growth of the female CApp with age; (b) to compare the effects of RXR and PPARy agonists in adult females of known age and (c) to explore the effect of masculinizing RXR agonists on the expression of RXR in the CApp. It was found that the CApp grows and develops with age. A significant increase in penile sheath length (PsL) and also in a developmental index (DI) was observed in 7-8 months old females, as compared with 4-5 months old ones. A reported endogenous agonist of RXR, 9-cis retinoic acid (9cis-RA), as well as two organotin compounds, tributyltin (TBT) and triphenyltin (TPT) which have been also reported to bind to RXR, were injected and its masculinizing effects were measured. Also, the effect of a PPARy agonist, rosiglitazone, was studied. All studied RXR agonists, but not the PPAR gamma agonist, were effective in increasing PsL, penile length (PL) and DI. Finally, the expression of the RXR in the CApp was studied (Western blot) in control, TBT, TPT, and 9cis-RA treated females. A significantly increased expression of RXR was only observed after 9cis-RA treatment. It is concluded that (a) development and growth of the CApp is significantly affected by female age; (b) reported RXR agonists, but not a PPARy agonist, cause female masculinization of young females. An appraisal of previous studies of female masculinization in the Ampullariidae has also been made and it is emphasized that the masculinizing effect of aging should be considered, particularly when interpreting field data.

Biosorption of crystal violet dye using inactive biomass of the fungus Diaporthe schini

Grassi, P ;Reis, C ; Drumm, FC ; Georgin, J ; Tonato, D ; Escudero, LB ; Kuhn, R ; Jahn, SL ; Dotto, GL ; WATER SCIENCE AND TECHNOLOGY ,2019 ,79 ,709 -717 .

An inactive biomass of a new fungus recently discovered, Diaporthe schini, was evaluated for the biosorption of crystal violet (CV) in simulated textile effluents. The characterization assays were performed using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and N-2 adsorption/desorption isotherms. The influences of pH and biosorbent dosage on the biosorption capacity were evaluated. Kinetics, equilibrium and thermodynamic studies were also carried out. Characterization techniques showed an amorphous biosorbent, with a rough surface containing irregular particles and surface area of 6.5 m(2) g(-1). The most adequate values of pH and biosorbent dosage were 7.5 and 0.4 g L-1, respectively. The Elovich kinetic model and the Sips equilibrium model were suitable to fit the experimental data. The biosorption capacity increased with temperature, reaching a maximum biosorption capacity of 642.3 mg g(-1 )at 328 K. The biosorption was a spontaneous and endothermic process. Diaporthe schini inactive biomass was an interesting biosorbent to treat colored effluents, presenting efficiency of 87% in the decolorization of a simulated dye house effluent.

The utilization of leaf-based adsorbents for dyes removal: A review

Bulgariu, L ;Escudero, LB ; Bello, OS ; Iqbal, M ; Nisar, J ; Adegoke, KA ; Alakhras, F ; Kornaros, M ; Anastopoulos, I ; JOURNAL OF MOLECULAR LIQUIDS ,2019 ,276 ,728 -747 .

The presence of organic dyes in the aquatic environment is a serious global problem because of the serious negative consequences on the quality of ecosystems. Among various physico-chemical methods, the adsorption could be considered a promising alternative for removing dyes from aqueous media, due to its efficiency, high selectivity, low cost, ease of operation, simplicity, and availability in a wide range of experimental conditions. However, all these advantages are closely related to the nature of adsorbent material used in the adsorption processes of dyes. The adsorbent materials available in large quantities requiring a simple preparation will enhance the benefits of the adsorption processes, in agreement with the concepts of green chemistry. This review is focused on the use of leaf-based materials, in raw or modified forms, as adsorbents for the removal of dyes from aqueous effluents, with applications in the wastewater treatment. This review addresses characterization of leaf-based adsorbents, possible utilization of leaf-based adsorbents (raw and activated forms) for dye removal and possible applications in pilot and full scale systems. Also, thermodynamics, equilibrium and kinetic parameters of dye adsorption on leaf-based adsorbents are discussed. The practical utility of leaf-based adsorbents for dye removal, and their possible uses in the treatment of industrial wastewater are copiously highlighted. (C) 2018 Elsevier B.V. All rights reserved.

Anisotropy and spin-fluctuation effects on the spectral properties of Shiba impurities

Andrade, JA ;Lobos, AM ; PHYSICAL REVIEW B ,2019 ,99 ,728 -747 .

We theoretically consider a quantum magnetic impurity coupled to a superconductor and obtain the local density of states at the position of the impurity taking into account the effect of spin fluctuations and single-ion magnetic anisotropy. We particularly focus on the spectrum of subgap Yu-Shiba-Rusinov (YSR or Shiba) states induced by a quantum impurity with easy- or hard-axis uniaxial anisotropy. Although this is a relevant experimental situation in, e.g., magnetic adatoms on the surface of clean metals, it is customary that theoretical descriptions assume a classical-spin approximation which is not able to account for single-ion anisotropy and other quantum effects. Here, quantum fluctuations of the spin are taken into account in the equations of motion of the electronic Green's function in the weak-coupling limit and considerably modify the energy of the Shiba states compared to the classical-spin approximation. Our results point towards the importance of incorporating quantum fluctuations and anisotropy effects for the correct interpretation of scanning tunneling microscopy (STM) experiments.

Focal adhesion kinase, RhoA, and p38 mitogen-activated protein kinase modulates apoptosis mediated by angiotensin II AT(2) receptors

Manzur, MJ ;Aguilera, MO ; Kotler, ML ; Beron, W ; Ciuffo, GM ; JOURNAL OF CELLULAR BIOCHEMISTRY ,2019 ,120 ,1835 -1849 .

Apoptosis plays an important role in cellular processes such as development, differentiation, and homeostasis. Although the participation of angiotensin II (Ang II) AT(2) receptors (AT R-2) in cellular apoptosis is well accepted, the signaling pathway involved in this process is not well established. We evaluated the participation of signaling proteins focal adhesion kinase (FAK), RhoA, and p38 mitogen-activated protein kinase (p38MAPK) in apoptosis induced by Ang II via AT R-2 overexpressed in HeLa cells. Following a short stimulation time (120 to 240minutes) with Ang II, HeLa-AT (2) cells showed nuclear condensation, stress fibers disassembly and membrane blebbing.FAK, classically involved in cytoskeleton reorganization, has been postulated as an early marker of cellular apoptosis. Thus, we evaluated FAK cleavage, detected at early stimulation times (15 to 30minutes). Apoptosis was confirmed by increased caspase-3 cleavage and enzymatic activity of caspase-3/7. Participation of RhoA was evaluated. HeLa-AT (2) cells overexpressing RhoA wild-type (WT) or their mutants, RhoA V14 (constitutively active form) or RhoA N19 (dominant-negative form) were used to explore RhoA participation. HeLa-AT (2) cells expressing the constitutively active variant RhoA V14 showed enhanced apoptotic features at earlier times as compared with cells expressing the WT variant. RhoA N19 expression prevented nuclear condensation/caspase activation. Inhibition of p38MAPK caused an increase in nuclear condensation and caspase-3/7 activation, suggesting a protective role of p38MAPK. Our results clearly demonstrated that stimulation of AT R-2 induce apoptosis with participation of FAK and RhoA while p38MAPK seems to play a prosurvival role.

Simplified analytical methodology for glucosinolate hydrolysis products: a miniaturized extraction technique and multivariate optimization

Fusari, CM ;Ramirez, DA ; Camargo, AB ; ANALYTICAL METHODS ,2019 ,11 ,309 -316 .

Miniaturized extraction techniques are one of the most significant advances in analytical chemistry today. Nowadays there is a growing tendency among food researchers to develop simpler and robust methodologies that allow the determination of multiple analytes in different samples. Based on this concept, the aim of this work was to develop an optimized and validated methodology for the determination of four isothiocyanates (ITCs) and one indole: allyl ITC, erucin, sulforaphane, phenyl ITC and indole-3-carbinol present in Brassicaceae vegetables. Experimental design and multivariate analysis were the statistical tools used during the process. The dispersive liquid-liquid microextraction (DLLME) technique developed in this work was successfully applied to the analysis of nine Brassicaceae species.

Transmembrane domain dimerization induces cholesterol rafts in curved lipid bilayers

Masone, D ;Bustos, DM ; PHYSICAL CHEMISTRY CHEMICAL PHYSICS ,2019 ,21 ,268 -274 .

Are the dimerization of transmembrane (TM) domains and the reorganization of the lipid bilayer two independent events? Does one event induce or interfere with the other? In this work, we have performed well-tempered metadynamics simulations to calculate the free energy cost to bend a model ternary lipid bilayer in the presence of a TM peptide in its dimer form. We have compared this result with the free energy cost needed to bend a bilayer-only system. Additionally, we have calculated the free energy cost to form a model TM peptide dimer quantitatively describing how lipids reorganize themselves in response to the increase of the membrane curvature and to the lipid-peptide interactions. Our results indicate that the formation of the peptide dimer inside the bilayer increases the cost of the membrane bending due to the spontaneous clustering of cholesterol molecules.

The Comings and Goings of Sheep and Pottery in the Coastal Desert of Namaqualand, South Africa

Dewar, G ;Marsh, EJ ; JOURNAL OF ISLAND & COASTAL ARCHAEOLOGY ,2019 ,14 ,17 -45 .

This paper evaluates chronological trends in the presence and absence of domestic animal bone (sheep, goat, and cattle) and pottery in Namaqualand, the proposed gateway to the rest of South Africa for early herders or hunter-gatherers with sheep and ceramics. We update date calibrations with local Delta R corrections and mixtures of recent calibration curves and include five previously unpublished dates. We use histograms of calibrated medians, sorted in 100-year bins, to assess sustained regional patterns with dates associated with domestic animal bone and pottery (n = 73). While too small to be useful as a population proxy, the current set of dates does reveal three pulses of occupation separated by two clear gaps, which we evaluate with a Bayesian model of three sequential phases. The model's boundaries are used as estimates of the dates of Early (AD 80-210), Middle (AD 490-790), and Late (AD 1180-1690) occupational phases separated by two substantial lapses of 280 and 380 years, respectively. The alternating phases of presence and absence are suggestively correlated with climate shifts, leading to a discussion of the idea that effective moisture was a crucial factor in choosing whether to occupy Namaqualand. The set of archaeological dates has greater temporal and spatial resolution than many regional climate data, so we suggest that these trends may more accurately reflect the variable conditions specific to Namaqualand, at least until they are refined by future climate research.

Stem volume model adjustment fitting for Populus x canadensis 'Conti 12' and 'Guardi' in irrigated plantations in Mendoza, Argentina

Mundo, IA ;Rovida-Kojima, EA ; Aschero, V ; BOSQUE ,2019 ,40 ,217 -226 .

Despite the extensive literature on model fitting to estimate volume in different tree species and regions of Argentina, the references related to volume equations for Populus spp. in irrigated plantations in the Province of Mendoza arc scarce. This information is essential for silvicultural management. The objectives of this study were: 1) to calculate and compare the artificial form factors for Populus x canadensis 'Conti 12' and 'Guardi' clones growing in irrigated plantations in Uco Valley, Mendoza, 2) to fit and compare different equations of stem volume with bark for these two clones and 3) to evaluate the possibility of using a single function to estimate this parameter in both clones. Seven models previously used on Populus in Argentina were fitted to estimate the total stem volume per tree. The form factors for 'Conti 12' and 'Guardi' were different between them (0.44 and 0.38, respectively). For both, 'Conti 12' and 'Guardi', the adjustment of the seven models allowed estimating the total stem volume with bark with a very high and similar degree of precision, although in both situations two models (Schumacher-Hall and a variant of the standard function with constant form factor) highlighted over the rest. The statistics of self-validation, homoscedasticity and parsimony criteria allow favoring the decision for the Schumacher-Hall model adjusted individually for each clone and not as a general expression.

An overview of the appendicular skeletal anatomy of South American titanosaurian sauropods, with definition of a newly recognized clade

Riga, BJG ;Lamanna, MC ; Otero, A ; David, LDO ; Kellner, AWA ; Ibiricu, LM ; ANAIS DA ACADEMIA BRASILEIRA DE CIENCIAS ,2019 ,91 ,217 -226 .

In the last two decades, the number of phylogenetically informative anatomical characters recognized in the appendicular skeleton of titanosaurian sauropod dinosaurs has increased dramatically with the discovery of new and comparatively complete specimens. Here we provide an overview of the appendicular skeletal morphology of South American titanosaurs and discuss its significance for phylogenetic reconstruction. The appendicular skeletal diversity of South American titanosaurs is substantially greater than was initially appreciated. Moreover, some regions of the appendicular skeleton, such as the pes, exhibit remarkable variability in form. Multiple synapomorphies of Titanosauria and the less inclusive clades Lithostrotia and Saltasauridae consist of characters of the girdles and limbs. Although the phylogenetic definitions of titanosaurian clades such as Saltasaurinae and Lognkosauria are stable, the taxonomic content of these chides has varied in recent analyses depending on the phylogenetic topology recovered. Within Titanosauria, the results of four recent, largely independent analyses support the existence of a derived titanosaurian lineage distinct from the 'Saltasaurinae line,' which is herein termed Colossosauria. At present, this clads is mainly comprised by taxa within Lognkosauria and Rinconsauria, and is useful in discussions of titanosaurian lower-level relationships.


Ubaldini, S ;Guglietta, D ; Trapasso, F ; Carloni, S ; Passeri, D ; Scotti, A ; CHEMISTRY JOURNAL OF MOLDOVA ,2019 ,14 ,32 -46 .

This paper presents an overview of the various innovative methodologies used in the recovery of valuable metals and critical raw materials (CRMs) from secondary sources. Valuable metals are interesting due to their vast industrial applications, high market prices and extensively used precious metal. The sanctuary value attributed to valuable metals such as gold during international political and economical crises and the limited resource of this metal, may explain the recent increasing gold share value. This article provides an overview of past achievements and presents scenario of studies carried out on the use of some promising methods which could serve as an economical means for recovering valuable metals and CRMs. The review also highlights the used varieties of application on large scale in real situations and hopes to provide insights into valorization of spent sources.

Baalsaurus mansillai gen. et sp. nov. a new titanosaurian sauropod (Late Cretaceous) from Neuquen, Patagonia, Argentina

Calvo, JO ;Riga, BG ; ANAIS DA ACADEMIA BRASILEIRA DE CIENCIAS ,2019 ,91 ,32 -46 .

We describe a dentary of a new titanosaur sauropod, Baalsaurus mansillai, gen. et sp. nov. from the Late Cretaceous of Patagonia, Argentina. The material comes from the Portezuelo Formation, Neuquen Group. Titanosaur sauropods lower jaws are scarce and only nine taxa with dentaries have been described. There are two types of morphology in titanosaur dentaries; "L" shaped or "U" shaped based on the shape, without a phylogenetic issue. In this paper; we recognize a new taxa, Baalsaurus mansillai, represented by an "L" shaped dentary with three apomorphic characters that are not present in other taxa: dentary alveoli with 10 teeth in the anterior ramus, a ventrally and anteriorly inclined symphysis and a wide ventral Meckelian groove surrounded by a thin lamina that forms a keel on the ventral border of the dentary.

Toxicity of wine effluents and assessment of a depuration system for their control: assay with tadpoles of Rhinella arenarum (BUFONIDAE)

Romero, ALN ;Moratta, MAH ; Rodriguez, MR ; Quiroga, LB ; Echegaray, M ; Sanabria, EA ; ECOTOXICOLOGY ,2019 ,28 ,48 -61 .

We evaluated the toxicity of the winery effluent and the efficiency of a symbiotic depuration system by means an experiment with Rhinella arenarum tadpoles. The studied effluent was taken from warehouses during the cleaning season. These effluents subsequently subjected to the purification treatment under evaluation. The effluent samples differentiated into two treatment levels: raw where the effluent was evaluated with field conditions and treated where the effluent was previously filtered with the symbiotic depuration system. The results of the bioassays compared with the physicochemical parameters determined in the effluent samples. The lethal response had a clear-cut correspondence with the effluent quality assessed utilizing physicochemical parameters. In all cases, dilution of the samples resulted in a significant reduction of their toxicity. It concluded that (a) winery effluents could be harmful to tadpoles of R. arenarum, (b) the symbiotic purification system used to treat wine effluents it would produce a significant reduction in the contaminant levels of the effluent. However, this reduction in contaminant levels does not provide sufficient safety for the release of the effluents into the environment.

Appetitive behavior of the honey bee Apis mellifera in response to phenolic compounds naturally found in nectars

Hernandez, IG ;Palottini, F ; Macri, I ; Galmarini, CR ; Farina, WM ; JOURNAL OF EXPERIMENTAL BIOLOGY ,2019 ,222 ,48 -61 .

The honey bee is the most frequently used species in pollination services for diverse crops. In onion crops (Allium cepa), however, bees avoid visiting certain varieties, being attracted differently to male sterile (MS) and fertile (OP) lines. These differences might be based on the phenolic profiles of the cultivars' nectars. To understand the relationship between nectar composition and pollinator attraction to different onion lines, we tested sensory and cognitive abilities and palatability in honey bees exposed to MS and OP onion nectars and sugar solutions mimicking them. We evaluated the proboscis extension response (PER) after antennal contact (unconditioned response) to MS or OP onion nectars, finding no statistical differences, which indicates similar gustatory perception for the two nectars. We also performed food uptake assays to test palatability of different artificial nectars, considering their flavonoids and potassium content. The presence of potassium decreased the palatability of the artificial nectars. Finally, we evaluated the bees' cognitive abilities when the reward (unconditioned stimulus) offered during conditioning PER assays presents differences in composition. We found that potassium by itself impaired learning; however, such impairment was even higher when naringenin and quercetin were added in the unconditioned stimulus (MS nectar mimic). Interestingly, potassium together with luteolin (OP nectar mimic) improved learning. Our study demonstrates that the differences in the nectars' flavonoid profiles combined with their high potassium content could explain the previously reported differences in attractiveness between onion lines, suggesting an important role of nectar compounds other than sugars for the attractiveness of flowers to pollinators.

Blue light attenuation mediates morphological and architectural acclimation of Vitis vinifera cv. Malbec to shade and increases light capture

Gonzalez, CV ;Jerez, DN ; Jofre, MF ; Guevara, A ; Prieto, J ; Mazza, C ; Williams, LE ; Giordano, CV ; ENVIRONMENTAL AND EXPERIMENTAL BOTANY ,2019 ,157 ,112 -120 .

Grapevine is one of the most important fruit crops worldwide. Vineyard management practices affect light interception and spectral characteristics inside the canopy. Plant photoreceptors drive shade acclimation responses after the perception of light signals such as low photosynthetic active radiation (PAR), low blue light (BL) levels and low red-to-far red ratios (R:FR). Grapevine plants effectively acclimate to shade but are irresponsive to variations in R:FR perceived by phytochromes. To determine if BL attenuation mediate shade acclimation in this species, we manipulated sunlight reaching the plants by filtering. Vitis vinifera cv. Malbec plants were grown under low (LOW PAR) and high (HIGH PAR) neutral light environments, and under high light but attenuating the BL component of the spectrum (-BLUE). We evaluated morphological, biochemical and architectural responses to shade, and modelled light interception (LIE) and absorption (E-a) efficiencies. We found that plants grown under -BLUE mimicked morphological and architectural responses of plants cultivated under LOW PAR. In addition, LIE and E-a were higher in plants grown under -BLUE and LOW PAR than in HIGH PAR. Our findings suggest that morphological and architectural responses to shade are under the control of BL-photo-receptors in grapevine. However, BL attenuation failed to induce the accumulation of photosynthetic pigments in leaves observed under LOW PAR. Unchanged biomass accumulation across light treatments suggests that improved light capture counterbalanced irradiance reduction. These results might help in the design of practices that manipulate irradiance in the field, and that are increasingly being used as environment-friendly management tools to improve crop performance.

Different trackway patterns in titanosaur sauropods: Analysis of new Titanopodus tracks from the Upper Cretaceous of Mendoza, Neuquen Basin, Argentina

Riga, BJG ;Tomaselli, MB ; CRETACEOUS RESEARCH ,2019 ,93 ,49 -59 .

The discovery of new Titanopodus trackways (Loncoche Formation, Argentina) shed light on the locomotion of titanosaur sauropods. Two patterns related with different size of trackmakers are identified based on ichnological and anatomical evidences. AC-1 and AC-4 trackways (pattern 1) are characterized by alternated manus and pes tracks. This is congruent with an asynchronous gait produced by large individuals that walked at 4.7-4.8 km/h. AC-3 trackway (pattern 2) shows some elongated and distorted tracks interpreted as overlapped manus and pes prints. This interpretation is supported by the presence of clear juxtaposed or partially overlapped manus and pes prints in some parts of the trackway. Pattern 2 is preliminary assigned to an amble gait produced by a smaller individual that walked at 3.7 km/h. These two patterns can be analyzed as different gaits in titanosaurs that walked together. (C) 2018 Elsevier Ltd. All rights reserved.

Deconstructing a complex obsidian "source-scape": A geoarchaeological and geochemical approach in northwestern Patagonia

Barberena, R ;Fernandez, MV ; Rughini, AA ; Borrazzo, K ; Garvey, R ; Lucero, G ; Della Negra, C ; Villanueva, GR ; Duran, V ; Cortegoso, V ; Giesso, M ; Klesner, C ; MacDonald, BL ; Glascock, MD ; GEOARCHAEOLOGY-AN INTERNATIONAL JOURNAL ,2019 ,34 ,30 -41 .

Northwestern Patagonia is located in a tectonically active part of the southern Andes (Argentina), which has facilitated the formation of obsidian, including pyroclastic deposits that have been affected by geomorphic processes, resulting in a complex obsidian landscape. To date, the geomorphic relocation of obsidian in the landscape has not been a focus of systematic research, and this hampers our understanding of prehistoric human mobility. We present an updated assessment of the regional availability of different obsidian types based on results from our research program, which combines geoarchaeological survey and geochemical characterization to understand the properties and distribution of obsidian. This robust "source-scape" provides the foundation for reconstructing patterns of lithic provisioning and discard. Our results suggest that interpretations of obsidian availability across the landscape should be more nuanced than is typically acknowledged. Based on our improved "source-scape," we discuss the patterns observed in an archaeological X-ray fluorescence database. When compared with the geoarchaeological reconstruction of obsidian availability, the archaeological record conforms to a distance-decay pattern. Contrary to previous interpretations, we suggest that the distribution of obsidian types is not isomorphic with human home ranges. This geoarchaeological research program provides a basis for integrating the archaeological record of different Andean regions.