Two Rieske Fe/S Proteins and TAT System in Mesorhizobium loti MAFF303099: Differential Regulation and Roles on Nodulation Basile, Laura Ana; Zalguizuri, Andrés; Briones, Carlos Gabriel; Lepek, Viviana Claudia Mesorhizobium loti MAFF303099 is a rhizobial strain that nodulates Lotus spp. A M. loti MAFF303099 mutant strain affected in the tatC gene was generated. This strain presented an altered protein secretion level to the culture supernatant and also a higher sensitivity to SDS. Its nodulation phenotype on Lotus showed the induction of small and colorless nodules, and in a larger number than those induced by the wild-type strain. In addition, these nodules presented defects in the degree of occupation by rhizobia. Two Rieske Fe/S proteins, encoded by the mll2707 and mlr0970 genes, were predicted as potential Tat substrates in M. loti MAFF303099. The transcriptional expression of mll2707 and mlr0970 genes was analyzed under different oxygen growth conditions. The mll2707 gene was expressed constitutively, while the expression of the mlr0970 gene was only detected under anaerobic and microaerophilic in vitro conditions. Both genes were down-regulated in the tatC mutant strain. mll2707 and mlr0970 mRNAs from the wild-type strain were detected in nodules. Using a translational reporter peptide fusion, we found that the Mll2707 protein was only detectable in the wild-type strain. On the other hand, although Mlr0970 protein was detected in wild-type and tatC mutant strains, its association with the membrane was favored in the wild-type strain. The tatC and the mll2707 mutant strains were affected in the cytochrome c oxidase activity. These results confirm that Mll2707 is required for cytochrome c-dependent respiration and that Tat functionality is required for the correct activity of Mll2707. The mll2707 mutant strain showed a nodulation phenotype similar to the tatC mutant strain, although it presented only a slight difference in comparison with wild-type strain in terms of nodule occupation. No defective phenotype was observed in the nodulation with the mlr0970 mutant strain. These results indicate that, of the two Rieske Fe/S proteins coded by M. loti MAFF303099, only Mll2707 expression is required for the induction of effective nodules, and that the functionality of the Tat system is necessary not only for the correct function of this protein, but also for some other protein required in an earlier stage of the nodulation process.

Optimization of β-cyclodextrin-based extraction of antioxidant and anti-browning activities from thyme leaves by response surface methodology Favre, Leonardo Cristian; dos Santos, Cristina; Lopez Fernandez, Maria Paula; Mazzobre, Maria Florencia; Buera, Maria del Pilar Thyme (Thymus vulgaris) has been demonstrated to extend the shelf-life of food products, being also a potential source of bioactive compounds. The aim of this research was to optimize the ultrasound assisted extraction employing β-cyclodextrin aqueous solutions as no-contaminant technology and Response Surface Methodology to obtain thyme extracts with the maximum antioxidant capacity. The optimal extraction conditions were: a solution of β-ciclodextrin 15 mM, an ultrasonic treatment time of 5.9 min at a temperature of 36.6 °C. They resulted in an extract with a polyphenolic content of 189.3 mg GAE/mL, an antioxidant activity (DPPH[rad]) of 14.8 mg GAE/mL, and ferric reducing/antioxidant power (FRAP) of 3.3 mg GAE/mL. Interestingly, the extract demonstrated to inhibit the production of Maillard browning products and can be considered a potential antiglycant agent. The obtained data is important for developing eco-friendly technologies in order to obtain natural antioxidant extracts with a potential inhibitory capacity of Maillard glycation reaction.

Amyloid oligomerization of the Parkinson's disease related protein α-synuclein impacts on its curvature-membrane sensitivity Gallea, Jose Ignacio; Ambroggio, Ernesto Esteban; Vilcaes, Aldo Alejandro; James, Nicholas G.; Jameson, David M.; Celej, Maria Soledad The amyloid aggregation of the presynaptic protein α-synuclein (AS) is pathognomonic of Parkinson's disease and other neurodegenerative disorders. Physiologically, AS contributes to synaptic homeostasis by participating in vesicle maintenance, trafficking, and release. Its avidity for highly curved acidic membranes has been related to the distinct chemistry of the N-terminal amphipathic helix adopted upon binding to appropriated lipid interfaces. Pathologically, AS populate a myriad of toxic aggregates ranging from soluble oligomers to insoluble amyloid fibrils. Different gain-of-toxic function mechanisms are linked to prefibrillar oligomers which are considered as the most neurotoxic species. Here, we investigated if amyloid oligomerization could hamper AS function as a membrane curvature sensor. We used fluorescence correlation spectroscopy to quantitatively evaluate the interaction of oligomeric species, produced using a popular method based on lyophilization and rehydration, to lipid vesicles of different curvatures and compositions. We found that AS oligomerization has a profound impact on protein-lipid interaction, altering binding affinity and/or curvature sensitivity depending on membrane composition. Our work provides novel insights into how the formation of prefibrillar intermediate species could contribute to neurodegeneration due to a loss-of-function mechanism.

Resightings of Two-banded Plovers (Charadrius falklandicus) during the breeding season in coastal Chubut, Patagonia, Argentina; Avistamientos de Chorlos Doble Collar (Charadrius falklandicus) durante el período reproductivo en la costa de Chubut, Patagonia, Argentina Hevia, Glenda Denise; Dallas Jordan, Fredrick; Terorde, Noé; Bertellotti, Néstor Marcelo; D'amico, Veronica Laura Presentamos avistamientos de Chorlos Doble Collar (Charadrius falklandicus) anillados en dos playas de la provincia de Chubut, Argentina: Playas Blancas (Península Valdés) y Playa Paraná (Puerto Madryn) separadas entre si aproximadamente 65 km en línea recta. En la temporada 2016, se capturaron y anillaron 24 individuos adultos durante la incubación. La mayoría de ellos (19, ca. 80%) fueron avistados en la temporada 2017, 17 en el mismo sitio donde fueron anillados y 2 en el otro sitio de estudio. El 32% se observó anidando mientras que, el 68% restante, se observó en el área descansando o alimentádose en forma solitaria o en bandadas mixtas con otras especies de aves playeras. Entre los individuos reproductores en 2017, dos anidaron con parejas también anilladas aunque diferentes al año anterior. Los reproductores restantes se observaron con parejas no marcadas, por lo que no se pudo evaluar si estaban apareados con el mismo individuo que en la temporada anterior. Estos resultados aportan nuevos datos sobre la biología reproductiva de esta especie que se suman a los estudios previos en la zona, sugiriendo que los Chorlos Doble Collar muestran fidelidad al sitio reproductivo.; We report resightings of individually-marked Two-banded Plovers (Charadrius falklandicus) breeding in northern Patagonia across two consecutive seasons in two beaches separated by approximately 65 km in a straight line: Playas Blancas (Península Valdés) and Playa Paraná (Puerto Madryn), Chubut province, Argentina. We captured and banded 24 adults at the nest while incubating during 2016. Nineteen banded individuals (ca. 80%) were resighted in 2017, 17 on the same site where they were banded, while 2 moved between survey sites. Only 32% were found breeding again while the remaining 68% were resighted resting or foraging, solitarily or in mixed flocks with other shorebird species. Among the resighted breeders, two adults were found paired with a different banded partner as in the previous year. The remaining breeders were paired with unbanded partners, and hence mate fidelity could not be assessed. Our findings add information to the scarce data on the breeding biology of this species suggesting that Two-banded Plovers exhibit site fidelity.

Pathogenic role of inflammatory response during Shiga toxin-associated hemolytic uremic syndrome (HUS) Exeni, Ramon Alfonso; Fernández Brando, Romina Jimena; Santiago, Adriana Patricia; Fiorentino, Gabriela Alejandra; Exeni, Andrea Mariana; Ramos, Maria Victoria; Palermo, Marina Sandra Hemolytic uremic syndrome (HUS) is defined as a triad of noninmune microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury. The most frequent presentation is secondary to Shiga toxin (Stx)-producing Escherichia coli (STEC) infections, which is termed postdiarrheal, epidemiologic or Stx-HUS, considering that Stx is the necessary etiological factor. After ingestion, STEC colonize the intestine and produce Stx, which translocates across the intestinal epithelium. Once Stx enters the bloodstream, it interacts with renal endothelial and epithelial cells, and leukocytes. This review summarizes the current evidence about the involvement of inflammatory components as central pathogenic factors that could determine outcome of STEC infections. Intestinal inflammation may favor epithelial leakage and subsequent passage of Stx to the systemic circulation. Vascular damage triggered by Stx promotes not only release of thrombin and increased fibrin concentration but also production of cytokines and chemokines by endothelial cells. Recent evidence from animal models and patients strongly indicate that several immune cells types may participate in HUS physiopathology: neutrophils, through release of proteases and reactive oxygen species (ROS); monocytes/macrophages through secretion of cytokines and chemokines. In addition, high levels of Bb factor and soluble C5b-9 (sC5b-9) in plasma as well as complement factors adhered to platelet-leukocyte complexes, microparticles and microvesicles, suggest activation of the alternative pathway of complement. Thus, acute immune response secondary to STEC infection, the Stx stimulatory effect on different immune cells, and inflammatory stimulus secondary to endothelial damage all together converge to define a strong inflammatory status that worsens Stx toxicity and disease.

Processing, structural, and biological evaluations of zirconia scaffolds coated by fluorapatite León, Laura Beltina; Albano, Maria Patricia; Garrido, Liliana Beatriz; Ferraz, Emanuela; Rosa, Adalberto; Oliveira, Paulo Tambasco de Highly porous zirconia (ZrO2) scaffolds fabricated by the replication method were coated with fluorapatite (FA). The FA coating was obtained by dipping the ZrO2 scaffolds into stabilized aqueous FA slips having different viscosity values (≤5.0 mPa.s). The influence of the FA slip viscosity and the immersion time on the reduction in the scaffold porosity and microstructure of the coated scaffolds were investigated. Cell spreading and survival of bone marrow-derived stromal cells (BMSC) and pre-osteoblastic MC3T3-E1 cells on the uncoated and coated scaffolds were examined using fluorescence and SEM microscopy, and MTT assay.The FA slip with the lowest viscosity value did not lead to a continuous film along the strut network and the macropores remained uncoated. The slips with the highest viscosity value produced a partial blocking of macropores. The porous structure obtained after coating with slips of 2.2 mPa.s viscosity for 2 seconds exhibited a low reduction in porosity and pore size (400-420 μm), due to the formation of the FA layer, and a continuous film distributed along the strut surfaces. Morphology, spreading, and survival of BMSC and MC3T3-E1 cells over a 7-day culture period evidenced good biocompatibility of FA-coated ZrO2 scaffolds processed by dip coating.

Influencia de los cambios en el uso del suelo y la precipitación sobre la dinámica hídrica de una cuenca de llanura extensa. Caso de estudio: Cuenca del Río Salado, Buenos Aires, Argentina; Influence of land use and rainfall changes on the water dynamics of a plain, an extensive flat river basin. Case study: The Salado River Basin, Buenos Aires, Argentina Garcia, Pablo Ezequiel; Badano, Nicolás Diego; Menendez, Angel Nicolas; Bert, Federico; García, Guillermo Ariel; Podestá, Guillermo; Rovere, Santiago; Verdin, Andrew; Rajagopalan, Balaji; Arora, Poonam La región pampeana de la República Argentina, una de las mayores llanuras del mundo, ha registrado en los últimos 50 años un fuerte ascenso en los niveles freáticos, con el consecuente aumento en la frecuencia de inundaciones. Esta dinámica tiene origen en dos procesos que se desarrollaron en ese período. En primer lugar, la zona presentó una tendencia hacia del aumento en las precipitaciones anuales. En segundo lugar se produjo un fuerte aumento del área dedicada a la agricultura, desplazando zonas con pasturas y pastizales, es decir, hubo un cambio en el uso del suelo. A través de ensayos numéricos con un modelo hidrológico (distribuido en el espacio y continuo en el tiempo, debidamente calibrado y verificado), se muestra en este trabajo que el aumento de las precipitaciones es el fenómeno que explica en mayor medida el incremento observado en los niveles freáticos, pero que la vegetación también juega un rol altamente significativo. Más aún, se pone de manifiesto la no linealidad de la respuesta del sistema hidrológico a los cambios en la precipitación y el uso del suelo, ya que la combinación de ambos efectos produce un resultado bastante inferior a la suma de cada uno de los efectos por separado. Adicionalmente, el modelo indica que existe una relación exponencial entre la profundidad de la napa y las áreas inundadas, estableciéndose una profundidad freática de 2 metros como el valor umbral a partir de la cual las áreas inundadas crecen significativamente.; The Argentine Pampas, one of the largest plains in the world, has experienced during the last 50 years a strong rise in its water table level, with a consequent increase in the frequency of floods. This dynamics is associated with two processes that took place in this zone during this period. First, the annual rainfall has shown a positive trend; and secondly, change over to field crops has expanded throughout the Pampas, displacing grasslands and pastures, so there has been a land use change. Based on numerical simulations with a properly calibrated and verified hydrological model, distributed in space and continuous in time, this paper shows that the increase in rainfall is the prime phenomenon explaining the increase in groundwater levels, but that vegetation has also played a very significant role. Moreover, the non-linear response of this hydrological system to changes in precipitation and land use was put into evidence, as the combination of both effects produces a result that is much less intense than the sum of each of the individual effects. In addition, the model indicates that there is an exponential relationship between water table depth and the flooded areas, identifying a value of 2 meters for the water table depth as a threshold below which the flooded area grows significantly.

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

Implementation of standard penalty procedures for the solution of incompressible Navier–Stokes equations, employing the element-free Galerkin method Álvarez Hostos, Juan Carlos; Fachinotti, Victor Daniel; Sarache Piña, Alirio Johan; Bencomo, Alfonso Daniel; Puchi Cabrera, Eli S. The present work introduces an alternative implementation of the element-free Galerkin method (EFGM) for the steady incompressible Navier-Stokes equations. The linear momentum balance and mass conservation equations have been developed on the basis of this global weak formulation. The weak forms of both equations have been coupled by means of two standard penalty procedures, which have been previously formulated and successfully employed in mesh-based numerical techniques such as the finite element method (FEM). These include the consistent penalty method (CPM) and reduced integration penalty method (RIPM). A detailed explanation concerning the characteristics inherent to the implementation of both penalty procedures in the EFGM based solutions for the incompressible Navier-Stokes equations, has also been provided. The resulting systems of equations have been adapted to the solution of different well-known incompressible flow benchmark problems. The feasibility and reliability of extending the implementation of these penalty procedures to the EFGM based solutions has been verified by comparison with the numerical techniques proposed and the results reported by other researchers. Results have revealed that this technique could be successfully used in the solution of Newtonian incompressible flow problems under the aforementioned penalty approaches.

Conformational sampling of the intrinsically disordered dsRBD-1 domain from: Arabidopsis thaliana DCL1 Suarez, Irina Paula; Gauto, Diego Fernando; Hails, Guillermo; Mascali, Florencia Carla; Crespo, Roberta; Zhao, Lingzi; Wang, Jin; Rasia, Rodolfo Maximiliano DCL1 is the ribonuclease that carries out miRNA biogenesis in plants. Substrate pri-miRNA recognition by DCL1 requires two double stranded RNA binding domains located at the C-terminus of the protein. We have previously shown that the first of these domains, DCL1-A, is intrinsically disordered and folds upon binding pri-miRNA. Integrating NMR and SAXS data, we study here the conformational landscape of free DCL1-A through an ensemble description. Our results reveal that secondary structure elements, corresponding to the folded form of the protein, are transiently populated in the unbound state. The conformation of one of the dsRNA binding regions in the free protein shows that, at a local level, RNA recognition proceeds through a conformational selection mechanism. We further explored the stability of the preformed structural elements via temperature and urea destabilization. The C-terminal helix is halfway on the folding pathway in free DCL1-A, constituting a potential nucleation site for the final folding of the protein. In contrast, the N-terminal helix adopts stable non-native structures that could hinder the correct folding of the protein in the absence of RNA. This description of the unfolded form allows us to understand details of the mechanism of binding-induced folding of the protein.

Elementos territoriales claves para la gestión del fuego en el Paraná medio Castro Diaz, Ivan Ricardo; Zamboni, Lisandra Pamela; Sione, Walter Fabian; Aceñolaza, Pablo Gilberto Yogüin es la palabra Chaná para denominar el fuego: principio activo de la relación entre la ganadería y el suelo en la región. Las implicaciones ambientales de su uso afectan directamente los recursos naturales y los servicios ambientales provistos por los ecosistemas del río Paraná en su tramo medio, en donde las afectaciones por la acelerada apropiación de la tierra para la ganadería dan paso a la configuración de diversas relaciones socioterritoriales productivas, culturales y ambientales isleñas. Este artículo presenta una serie de elementos efectivos para la planificación estratégica, siendo claves para la comprensión de la problemática desde la perspectiva del desarrollo sustentable. A partir de la definición del papel del fuego en la región, se explicitan los actores territoriales involucrados en la causalidad sistémica y variables asociadas a procesos de pampeanización presentes en la dinámica del lugar.

Mechanism of Tetramer Dissociation, Unfolding, and Oligomer Assembly of Pneumovirus M2-1 Transcription Antiterminators Esperante, Sebastian; Álvarez Paggi, Damián Jorge; Salgueiro, Mariano; de Prat Gay, Gonzalo Among Mononegavirales, the Pneumovirus family stands out by its RNA polymerase processivity that relies on a transcription antiterminator, the M2-1 protein, which also plays a key role in viral particle assembly. Biophysical and structural evidence shows that this RNA-binding tetramer is strongly modulated by a CCCH Zn2+ binding motif. We show that while the global dissociation/unfolding free energy is 10 kcal mol-1, more stable for the respiratory syncytial virus M2-1, the human metapneumovirus (HMPV) counterpart shows a 7 kcal mol-1 higher intersubunit affinity. Removal of Zn2+ from both homologues leads to an apo-monomer of identical secondary structure that further undergoes a slow irreversible oligomerization. Mutation of the histidine residue of the Zn2+ motif to cysteine or alanine leads directly to large oligomers, strongly suggesting that metal coordination has an exquisite precision for modulating the quaternary arrangement. Zn2+ removal is very slow and requires subdenaturing concentrations of guanidine chloride, suggesting a likely local folding energy barrier. Exploring a broad combination of denaturant and ethylenediaminetetraacetic acid conditions, we showed that the metapneumovirus protein has to overcome a higher energy barrier to trigger Zn2+ removal-driven dissociation, in concordance with a slower dissociation kinetics. In silico modeling of open and close conformations for both M2-1 tetramers together with interaction energy calculations reveals that the gradual opening of protomers decreases the number of intersubunit contacts. Half of the interaction energy holding each protomer in the tetramer comes from the CCCH motif, while HMPV-M2-1 harbors additional contacts between the CCCH motif of one subunit and the core domain of a protomer located in trans, allowing the rationalization of the experimental data obtained. Overall, the evidence points at a key role of the CCCH motif in switching between structural and consequently functional alternatives of the M2-1 protein.

Interrogating pollution sources in a mangrove food web using multiple stable isotopes Souza, Iara da C.; Arrivabene, Hiulana P.; Craig, Carol-Ann; Midwood, Andrew J.; Thornton, Barry; Matsumoto, Silvia T.; Elliott, Michael; Wunderlin, Daniel Alberto; Monferran, Magdalena Victoria; Fernandes, Marisa N. Anthropogenic activities including metal contamination create well-known problems in coastal mangrove ecosystems but understanding and linking specific pollution sources to distinct trophic levels within these environments is challenging. This study evaluated anthropogenic impacts on two contrasting mangrove food webs, by using stable isotopes (δ13C, δ15N, 87Sr/86Sr, 206Pb/207Pb and 208Pb/207Pb) measured in sediments, mangrove trees (Rhizophora mangle, Laguncularia racemosa, Avicennia schaueriana), plankton, shrimps (Macrobranchium sp.), crabs (Aratus sp.), oysters (Crassostrea rhizophorae) and fish (Centropomus parallelus) from both areas. Strontium and Pb isotopes were also analysed in water and atmospheric particulate matter (PM). δ15N indicated that crab, shrimp and oyster are at intermediate levels within the local food web and fish, in this case C. parallelus, was confirmed at the highest trophic level. δ15N also indicates different anthropogenic pressures between both estuaries; Vitória Bay, close to intensive human activities, showed higher δ15N across the food web, apparently influenced by sewage. The ratio87Sr/86Sr showed the primary influence of marine water throughout the entire food web. Pb isotope ratios suggest that PM is primarily influenced by metallurgical activities, with some secondary influence on mangrove plants and crabs sampled in the area adjacent to the smelting works. To our knowledge, this is the first demonstration of the effect of anthropogenic pollution (probable sewage pollution) on the isotopic fingerprint of estuarine-mangrove systems located close to a city compared to less impacted estuarine mangroves. The influence of industrial metallurgical activity detected using Pb isotopic analysis of PM and mangrove plants close to such an impacted area is also notable and illustrates the value of isotopic analysis in tracing the impact and species affected by atmospheric pollution.

Biogeographic shell shape variation in trophon Geversianus (gastropoda: muricidae) along the Southwestern Atlantic coast Malvé, Mariano Ezequiel; Rivadeneira Valenzuela, Marcelo Michel; Gordillo, Sandra Broad-scale latitudinal morphological trends in gastropods along the southwestern Atlantic coast are scant, since the majority of studies have focused on local scales. Here, we evaluate biogeographic shell shape variation in the marine gastropod Trophon geversianus across most of its distributional range, covering 14 degrees of latitude. Samples come from death assemblages which have the potential to unveil biogeographic patterns along spatio-temporal scales and are not affected by short-term volatility in comparison with living assemblages. We performed morphometric analyses on shells from death assemblages, and compared shape variation between mid-Holocene and modern shells from one southern site. Multivariate analyses identified two morphotypes matching the biogeographic regions of the Argentine Sea that segregates a warm-temperate from a cold-temperate zone. The Magellan province morphotype is characterized by a larger shell, lower spire height, and higher aperture length than the Argentinean province morphotype. This change in shell shape is significantly correlated to sea surface temperature, even after accounting for spatial autocorrelation, which could be indirectly influencing intraspecific morphoclines via shifts in growth rates. On the other side, shell size and shape variations were also detected (size increase over recent geological time) between mid-Holocene and modern specimens at the Beagle Channel, which could be attributed to paleoenvironmental changes and to shifts in predator-prey relationships. Our study illustrates the usefulness of death assemblages for revealing large-scale patterns of shell-shape variability in mollusk species, and highlights the spatial coincidence of intraspecific morphological differentiation with the transition zone between biogeographic provinces of the Argentine Sea.

Parabolic megadunes in a subtropical Quaternary inland dune field, southwestern Pampas, Argentina Tripaldi, Alfonsina; Mehl, Adriana Ester; Zárate, Marcelo Arístides The Utracán paleo-dune field (La Pampa Province, Argentina, southern South America) was examined by remote sensing, morphometric analyses and field surveys as a case study of complex megadunes of inland deserts. The paleo-dune field is within the Utracán-Argentino valley, one of the transverse valleys of La Pampa Province excavated into a regional structural plain. Similar paleo-dune fields occur within these valleys. Utracán dunes are mostly stabilized by grasses, deeply disturbed by cattle grazing and agriculture. The paleo-dune field is formed by complex parabolic megadunes with superimposed dunes. Parabolic megadunes present lengths of trailing arms of 3.3–12.9 km, widths between them of 2–2.9 km and heights of 7–38 m. The position of the dune noses at the northeastern tip of the bedform and measured SW-NE orientation of arms indicate a mean transport direction to azimuth 68.2°. Above the parabolic arms, and isolated in the paleo-dune field, there are compound blowout dunes (clusters of several blowouts forming a larger bedform). They show the depositional lobes to the NE, with a measured mean transport direction to azimuth 58.1°. The SW-NE longitudinal length varies between 324 and 1302 m and the NW-SE transverse length between 114 and 622 m. Other parabolic arms show low (<3 m) barchanoid dunes, with crest lengths of 48–811 m, a mean crest spacing of 74 m and a transport direction to azimuth 28.2°. The paleo-dune field also shows smaller, simple parabolic and blowout dunes. We hypothesize that the parabolic and blowout dunes are the basic bedforms that emerged under the boundary conditions of the Utracán dune field, related to a high sediment supply coupled with a partial vegetation cover, in a valley that provided accommodation space by means of well-defined depression and wind deceleration due to a change in the longitudinal valley slope direction. The west-to-east spatial progression of dune morphologies along the Utracán-Argentino valley, the general transport direction of dunes to the NE, and the petrographic sand composition allow us the infer that the transverse valleys of La Pampa Province worked as sand transport pathways. These pathways transferred fine to very fine sand from the eastern Andean piedmont to the Pampean plain, likely during the Quaternary.

Neuroprotective effects of Flaveria bidentis and Lippia salsa extracts on SH-SY5Y cells Cavallaro, Valeria; Baier, Carlos Javier; Murray, María Gabriela; Estevez Braun, Ana; Murray, Ana Paula Halophyte plants have to survive in a hostile environment by developing adaptive responses. One of these strategies is the production of several protective molecules which make these plants an interesting source of bioactive compounds. Significant acetylcholinesterase inhibition was observed for ethanolic extracts obtained from Lippia salsa Griseb. (Verbenaceae) and Flaveria bidentis (L.) Kuntze (Asteraceae), two plants that are widely distributed in the salt marsh Salitral de la Vidriera. These results encouraged us to further study the active constituents and the potential neuroprotective properties of these plants. The flavonoids luteolin (1) and apigenin (2) were identified as the active components of L. salsa, while 6-methoxykaempferol-3-sulfate (3) was obtained from F. bidentis. In addition, we investigated the cytotoxicity, cellular protection against K+-depolarization and antioxidant activity in SH-SY5Y neuroblastoma cells for these extracts and compound 3. Results demonstrated that beyond acting as acetylcholinesterase inhibitors, they also exhibited neuroprotective effects against KCl-induced-Ca2 + overload and oxidative stress.

Iodine-Catalyzed Iso-Nazarov Cyclization of Conjugated Dienals for the Synthesis of 2-Cyclopentenones Marsili, Lucía A.; Pergomet, Jorgelina Leonor; Gandon, Vincent; Riveira, Martín Jorge Molecular iodine was identified as an efficient catalyst for the cycloisomerization of conjugated dienals to substituted 2-cyclopentenones. DFT calculations suggested an unexpected concerted character for this cyclization.

Online third-order liquid chromatographic data with native and photoinduced fluorescence detection for the quantitation of organic pollutants in environmental water Pellegrino Vidal, Rocio; Olivieri, Alejandro Cesar; Ibañez, Gabriela Alejandra; Escandar, Graciela Monica Third-order liquid chromatographic data were generated online for the simultaneous quantitation of six organic environmental pollutants. The employed strategy consists in reducing the linear flow rate at the column outlet. A postcolumn UV reactor and a fluorimetric detector allowed to properly record both photoinduced and native excitation-emission fluorescence matrices (EEPIFMs and EEFMs, respectively). The obtained third-order liquid chromatography data were chemometrically processed with the multivariate curve resolution-alternating least-squares model. The sensitivity of the overall analytical method was enhanced by a very simple solid-phase extraction with C18 membranes, to be able to successfully apply it to natural water samples tested as real matrices. Favorable detection limits for the investigated pollutants, ranging from 0.02 to 0.27 ng mL-1, were attained, with relative prediction errors between 2 and 7%. Since the studied samples contain uncalibrated interferents, the applied strategy achieves the second-order advantage. Implications regarding the potential achievement of the third-order advantage are discussed.

Educación en tiempos de la Confederación Argentina; Education in times of the Argentine Confederation Bustamante Vismara, José Manuel Laureano Este análisis indaga en dos facetas de la política educativa desarrollada bajo el gobierno de la Confederación Argentina en la década de 1850. Por un lado se recuperan rasgos del proyecto alberdiano, sus modulaciones al formularse el artículo quinto de la constitución de 1853, así como las notas introducidas por la reforma de 1860. Luego se estudian aspectos fiscales y educativos de ese gobierno. Con este propósito se atiende a legajos de órdenes de pago del Departamento de Justicia, Culto e Instrucción Pública durante el período comprendido entre 1856 y 1860.; This paper searches two facets of the educational policy developed under the government of the Argentine Confederation in the 1850s. On one hand, traces of the Alberdian project are recovered, their modulations in the formulation of the fifth article of the constitution of 1853, as well as the notes introduced by the reform of 1860. Later we study fiscal and educational aspects of that government; the payment orders of the Department of Justicia, Culto e Instrucción Pública during the period between 1856 and 1860 are analyzed for that purpose.

Ni-based catalysts obtained from perovskites oxides for ethanol steam reforming Aguero, Fabiola Nerina; Alonso, José Antonio; Fernández Díaz, Maria Teresa; Cadus, Luis Eduardo Perovskites as host structures of cations were used in order to generate in situ active and stable catalysts for ethanol steam reforming. For this purpose, La1-xMgxAl1-yNiyO3 (x = 0.1; y= 0, 0.1, 0.2, 0.3) perovskites were synthetized by the citrate method. Ni segregation is evident for a substitution level higher than 0.2. The segregation of Ni as NiO generated species interacts with different metal-support after the reduction step. The y= 0.1 catalyst presents the highest H2 yield value about 85% during reaction time, with low mean values of CH4 and CO selectivities of 3.4% and 11%, respectively and a low carbon formation. The better performance of y= 0.1 catalyst could be attributed to the minor proportion of segregated phases, thus a controlled expulsion of Ni is successfully reached.