Bromopyrrole alkaloids isolated from the Patagonian bryozoan Aspidostoma giganteum
Patiño Cano, Laura P.; Muniain, Claudia Cristina; Knott, María Elena; Puricelli, Lydia Ines; Palermo, Jorge Alejandro
Nine new bromopyrrole alkaloids, aspidostomides A–H and aspidazide A (1–9), were isolated from the Patagonian bryozoan Aspidostoma giganteum. Aspidostomides A–H have dibromotyrosine- or bromotryptophan-derived moieties forming either linear amides or pyrroloketopiperazine-type lactams with a bromopyrrole carboxylic acid as a common structural motif. On the other hand, aspidazide A is a rare asymmetric acyl azide formed by an N–N link of two different pyrroloketopiperazine lactams and is the first isolated compound of this class from marine invertebrates. This work is the first report of secondary metabolites isolated from a bryozoan from the Patagonian region. The structures of compounds 1–9 were elucidated by spectroscopic methods and chemical transformations. One of these compounds, aspidostomide E (5), was moderately active against the 786-O renal carcinoma cell line.
Phylodynamics of vampire bat-transmitted rabies in Argentina
Torres, Carolina; Lema, C.; Gury Dohmen, F.; Beltran, F.; Novaro, L.; Russo, S.; Freire, M. C.; Velasco Villa, A.; Mbayed, Viviana Andrea; Cisterna , D. M.
Common vampire bat populations distributed from Mexico to Argentina are important rabies reservoir hosts in Latin America. The aim of this work was to analyse the population structure of the rabies virus (RABV) variants associated with vampire bats in the Americas and to study their phylodynamic pattern within Argentina. The phylogenetic analysis based on all available vampire bat-related N gene sequences showed both a geographical and a temporal structure. The two largest groups of RABV variants from Argentina were isolated from northwestern Argentina and from the central western zone of northeastern Argentina, corresponding to livestock areas with different climatic, topographic and biogeographical conditions, which determined their dissemination and evolutionary patterns. In addition, multiple introductions of the infection into Argentina, possibly from Brazil, were detected. The phylodynamic analysis suggests that RABV transmission dynamics is characterized by initial epizootic waves followed by local enzootic cycles with variable persistence. Anthropogenic interventions in the ecosystem should be assessed taking into account not only the environmental impact but also the potential risk of disease spreading through dissemination of current RABV lineages or the emergence of novel ones associated with vampire bats.
Mean shape of interplanetary shocks deduced from in situ observations and its relation with interplanetary CMEs
Janvier, M.; Demoulin, P.; Dasso, Sergio Ricardo
CONTEXT: Shocks are frequently detected by spacecraft in the interplanetary space. However, the in situ data of a shock do not provide direct information on its overall properties even when a following interplanetary coronal mass ejection (ICME) is detected. AIMS: The main aim of this study is to constrain the general shape of ICME shocks with a statistical study of shock orientations. METHODS: We first associated a set of shocks detected near Earth over 10 years with a sample of ICMEs over the same period. We then analyzed the correlations between shock and ICME parameters and studied the statistical distributions of the local shock normal orientation. Supposing that shocks are uniformly detected all over their surface projected on the 1 AU sphere, we compared the shock normal distribution with synthetic distributions derived from an analytical shock shape model. Inversely, we derived a direct method to compute the typical general shape of ICME shocks by integrating observed distributions of the shock normal. RESULTS: We found very similar properties between shocks with and without an in situ detected ICME, so that most of the shocks detected at 1 AU are ICME-driven even when no ICME is detected. The statistical orientation of shock normals is compatible with a mean shape having a rotation symmetry around the Sun-apex line. The analytically modeled shape captures the main characteristics of the observed shock normal distribution. Next, by directly integrating the observed distribution, we derived the mean shock shape, which is found to be comparable for shocks with and without a detected ICME and weakly affected by the limited statistics of the observed distribution. We finally found a close correspondence between this statistical result and the leading edge of the ICME sheath that is observed with STEREO imagers. CONCLUSIONS: We have derived a mean shock shape that only depends on one free parameter. This mean shape can be used in various contexts, such as studies for high-energy particles or space weather forecasts.
Biogenesis of the oxidative phosphorylation machinery in plants. From gene expression to complex assembly
Gonzalez, Daniel Hector; Giegé, Philippe
This Research Topic is aimed at establishing a collection of articles that focus on the different processes involved in the biogenesis of respiratory complexes in plants as a means to highlight recent advances. In this way, it intends to help to construct a picture of the whole process and, not less important, to expose the existing gaps that need to be addressed to fully understand how plant cells build and modulate the complex structures involved in respiration.
Nitric-oxide-mediated cell death is triggered by chitosan in Fusarium eumartii spores
Terrile, Maria Cecilia; Mansilla, Andrea Yamila; Albertengo, Liliana; Rodríguez, María Susana; Casalongue, Claudia
BACKGROUND: The genus Fusarium comprises a heterogeneous group of fungi important for agriculture. Fusarium solani f. sp. eumartii (F. eumartii), historically considered to be a fungal pathogen of potato, has also been associated with tomato disease. Currently, chitosan and its derivatives have been receiving more attention as environmentally friendly antimicrobial compounds in sustainable practices. The aim of the present work was to characterize downstream events associated with the mode of action of chitosan, including nitrosative reactive species, in order to identify new biomarkers of its cytotoxic action. RESULTS: Data indicated that chitosan-mediated nitric oxide (NO) production might lead to conidial death, concomitant with the strong reduction in fungal pathogenicity in tomato plants. Following chitosan applications, a notably dose-dependent reduction in conidial viability was demonstrated in F. eumartii. Thereafter, the infectivity of chitosan-treated spores was tested by a bioassay using tomato seedlings. CONCLUSION: All these data highlight NO valuable properties as a quantitative and qualitative biomarker of cytotoxic action of chitosan in conidial cells. In addition, these findings place the chitosan assayed here as a fungicide with a high potential of application in sustainable horticultural practices.
Reduced order generalised integrator-based current controller applied to shunt active power filters
Gómez Jorge, Sebastián; Busada, Claudio A.; Solsona, Jorge Alberto
This study proposes the application of a current controller based on the reduced order generalised integrator (ROGI) to control a three-phase three-wire shunt active power filter (SAPF). The ROGI-based controller has low computational burden and it is suitable for its implementation in low-cost digital signal processors (DSPs). This controller is also frequency adaptive. This allows it to maintain its high steady-state performance despite grid frequency variations. Unlike conventional high performance SAPFs this current controller does not require the computation of high quality current references (with low distortion and total harmonic distortion below that recommended by the IEEE Std 519-1992). Therefore most of the available computational power can be used for compensating the harmonics produced by the load.
The evolution of signal-reward correlations in bee and hummingbird-pollinated species of Salvia
Benitez-Vieyra, Santiago Miguel; Fornoni, Juan; Pérez Alquicira, Jessica; Boege, Karina; Domínguez, César
Within-individual variation in floral advertising and reward traits is a feature experienced by pollinators that visit different flowers of the same plant. Pollinators can use advertising traits to gather information about the quality and amount of rewards, leading to the evolution of signal?reward correlations. As long as plants differ in the reliability of their signals and pollinators base their foraging decisions on this information, natural selection should act on within-individual correlations between signals and rewards. Because birds and bees differ in their cognitive capabilities, and use different floral traits as signals, we tested the occurrence of adaptive divergence of the within-individual signal?reward correlations among Salvia species that are pollinated either by bees or by hummingbirds. They are expected to use different floral advertising traits: frontal traits in the case of bees and side traits in the case of hummingbirds. We confirmed this expectation as bee- and hummingbird-pollinated species differed in which specific traits are predominantly associated with nectar reward at the within-individual level. Our findings highlight the adaptive value of within-individual variation and covariation patterns, commonly disregarded as ?environmental noise?, and are consistent with the hypothesis that pollinator-mediated selection affects the correlation pattern among floral traits.
La Flora Poínica durante el Holoceno en el Oeste del Iberá, Corrientes. Argentina
Fernandez Pacella, Lionel Edgar
El presente trabajo está destinado a estudiar la palinología duran-te el Holoceno en el margen oeste del Iberá. Con la denominación Esteros del Iberá, identificamos a uno de los humedales tropicales más importantes de la biósfera en términos de su extensión y de las especies que lo habitan. El objetivo es conocer las especies predomi-nantes del Holoceno del Iberá, aportando información (muy escasa hasta el momento) sobre la paleodiversidad vegetacional fósil. Se muestrearon 11 lagunas ubicadas en el margen occidental del macro-sistema y se realizaron las descripciones de los diferentes palinomor-fos, para ello se midieron los parámetros comúnmente utilizados en las descripciones palinológicas, la identificación y determinación de los granos de polen se realizó mediante comparación con la colección de referencia y la bibliografía especializada. Dada la amplia diversi-dad de las comunidades tropicales en el Iberá, es importante docu-mentar, a través de floras polínicas, la morfología de las distintas especies. El desarrollo del trabajo acompañado con otros estudios de este tipo aportará datos para la reconstrucción climatológica del Holoceno en la región y será de gran utilización para los organismos de planificación y manejo de recursos naturales para la conservación del Iberá a corto, mediano y largo plazo.
Stability of cosmological deflagration fronts
Membiela, Federico Agustin; Megevand, Ariel Hugo
In a cosmological first-order phase transition, bubbles of the stable phase nucleate and expand in the supercooled metastable phase. In many cases, the growth of bubbles reaches a stationary state, with bubble walls propagating as detonations or deflagrations. However, these hydrodynamical solutions may be unstable under corrugation of the interface. Such instability may drastically alter some of the cosmological consequences of the phase transition. Here, we study the hydrodynamical stability of deflagration fronts. We improve upon previous studies by making a more careful and detailed analysis. In particular, we take into account the fact that the equation of motion for the phase interface depends separately on the temperature and fluid velocity on each side of the wall. Fluid variables on each side of the wall are similar for weakly first-order phase transitions, but differ significantly for stronger phase transitions. As a consequence, we find that, for large enough supercooling, any subsonic wall velocity becomes unstable. Moreover, as the velocity approaches the speed of sound, perturbations become unstable on all wavelengths. For smaller supercooling and small wall velocities, our results agree with those of previous works. Essentially, perturbations on large wavelengths are unstable, unless the wall velocity is higher than a critical value. We also find a previously unobserved range of marginally unstable wavelengths. We analyse the dynamical relevance of the instabilities, and we estimate the characteristic time and length scales associated to their growth. We discuss the implications for the electroweak phase transition and its cosmological consequences.
Stress in wild Greater Rhea populations: effects of agricultural activities on seasonal excreted glucocorticoid metabolite levels
Leche, Alvina; Bazzano, Gisela del Valle; Hansen, C.; Navarro, Joaquin Luis; Marin, Raul Hector; Martella, Monica Beatriz
In recent years, wild populations of Greater Rhea (Rhea americana) have declined drastically, due mainly to the conversion of grassland into cropland as a result of intensive, specialized agricultural practices. In this study we evaluate potential stressfuleffects of agricultural activities on this ratite by assessing their adrenocortical response. Specifically, we compared fecal glucocorticoid metabolite (FGM) levels of rheas living in two areas under very different land use: grasslands mainly devoted to cattle grazing and agro-ecosystems intensively used for crop production. Radioimmunoanalysis of fecal samples from 269 individuals indicated no significant differences in mean concentrations of FGM according to habitat type. In the agro-ecosystem we found no direct effect between agricultural practice and the bird´s FGM levels. However, FGM concentrations were significantly higher during the dry season, which may represent a stress response to the low availability of forage due to harvesting. In contrast, no increase in the FGM levels was registered during the dry season in the grassland, where ample forage was available throughout the year. In this environment the highest increases in FGM levels coincided with the reproductive period, likely due to the frequent agonist encounters between males at this time of the year. Our findings therefore suggest that the consequences of agricultural practices may constitute a chronic environmental stressor for Greater Rhea populations living under such conditions. The present study support earlier research showing detrimental impacts of agricultural activities on this species, whose area of distribution coincides with the most productive regions of South America.
When shape matters: Strategies of different Antarctic ascidians morphotypes to deal with sedimentation
Torre, Luciana; Abele, Doris; Lagger, Cristian Fabian; Momo, Fernando; Sahade, Ricardo Jose
Climate change leads to increased melting of tidewater glaciers in the Western Antarctic Peninsula region and sediment bearing glacial melt waters negatively affects filter feeding species as solitary ascidians. In previous work the erect-forms Molgula pedunculata and Cnemidocarpa verrucosa (Order Stolidobranchiata) appeared more sensitive than the flat form Ascidia challengeri (Order Phlebobranchiata). Sedimentation exposure is expected to induce up-regulation of anaerobic metabolism by obstructing the organs of gas exchange (environmental hypoxia) or causes enhanced squirting activity (functional hypoxia). In this study we evaluated the possible relationship between ascidian morphotype and their physiological response to sedimentation. Together with some behavioural observations, we analysed the response of anaerobic metabolic parameters (lactate formation and glycogen consumption) in different tissues of three Antarctic ascidians, exposed to high sediment concentrations. The results were compared to experimental hypoxia (10% pO2) and exercise (induced muscular contraction) effects, in order to discriminate the effect of sediment on each species and morpho-type (erect vs. flat forms). Our results suggest that the styled (erect) C. verrucosa increases muscular squirting activity in order to expulse excessive material, while the flat-form A. challengeri reacts more passively by down-regulating its aerobic metabolism under sediment exposure. Contrary, the erect ascidian M. pedunculata did not show any measurable response to the treatments, indicating that filtration and ingestion activities were not reduced or altered even under high sedimentation (low energetic material) which could be disadvantageous on the long-term and could explain why M. pedunculata densities decline in the study area.
Extraction of jojoba oil with liquid CO2 + propane solvent mixtures
Palla, Camila Andrea; Hegel, Pablo Ezequiel; Pereda, Selva; Bottini, Susana Beatriz
In this work liquid CO2/propane mixtures were used to extract jojoba oil from oilseeds. First, experiments at 313 K and pressures of 70 bar and 200 bars were carried out on jojoba oil deposited on glass spheres, using different solvent concentrations (30 wt%, 50 wt% and 70 wt% CO2), to assess the influence of the solvent composition and phase behavior on the extraction rate. Then, jojoba oil was extracted from the milled seeds under homogeneous liquid conditions, using solvent mixtures containing 30 wt% and 50 wt% CO2 at 70 bar and 313 K. A solvent mixture with 30 wt% CO2 exhibited good solvent power. Oil extraction yields of 98 % were obtained using a minimum solvent to oilseed mass ratio of 5 g solvent / g oilseed and operating the extractor at 313 K and 70 bar.
A potent combination microbicide that Targets SHIV-RT, HSV-2 and HPV
Kizima, Larisa; Rodríguez, Aixa Inés; Kenney, Jessica; Derby, Nina; Mizenina, Olga; Menon, Radhika; Seidorm, Samantha; Zhang, Shimin; Levendosky, Keith; Ninochka, Jean-Pierre; Pugach, Pavel; Villegas, Guillermo; Ford, Brian E.; Gettie, Agegnehu; Blanchard, James; Piatak, Michael Jr.; Lifson, Jeffrey D.; Paglini, Maria Gabriela; Teleshova, Natalia; Zydowsky, Thomas M.; Robbiani, Melissa; Fernández Romero, José
Prevalent infection with human herpes simplex 2 (HSV-2) or human papillomavirus (HPV) is associated with increased human immunodeficiency virus (HIV) acquisition. Microbicides that target HIV as well as these sexually transmitted infections (STIs) may more effectively limit HIV incidence. Previously, we showed that a microbicide gel (MZC) containing MIV-150, zinc acetate (ZA) and carrageenan (CG) protected macaques against simian-human immunodeficiency virus (SHIV-RT) infection and that a ZC gel protected mice against HSV-2 infection. Here we evaluated a modified MZC gel (containing different buffers, co-solvents, and preservatives suitable for clinical testing) against both vaginal and rectal challenge of animals with SHIV-RT, HSV-2 or HPV. MZC was stable and safe in vitro (cell viability and monolayer integrity) and in vivo (histology). MZC protected macaques against vaginal (p<0.0001) SHIV-RT infection when applied up to 8 hours (h) prior to challenge. When used close to the time of challenge, MZC prevented rectal SHIV-RT infection of macaques similar to the CG control. MZC significantly reduced vaginal (p<0.0001) and anorectal (p = 0.0187) infection of mice when 106 pfu HSV-2 were applied immediately after vaginal challenge and also when 5×103 pfu were applied between 8 h before and 4 h after vaginal challenge (p<0.0248). Protection of mice against 8×106 HPV16 pseudovirus particles (HPV16 PsV) was significant for MZC applied up to 24 h before and 2 h after vaginal challenge (p<0.0001) and also if applied 2 h before or after anorectal challenge (p<0.0006). MZC provides a durable window of protection against vaginal infection with these three viruses and, against HSV-2 and HPV making it an excellent candidate microbicide for clinical use.
¿Y si el Papa fuera una mujer?
Sucksdorf, Cristián
La enorme presencia de mujeres en las más altas esferas del poder no puede ser un dato ignorado al momento de analizar la vitalidad del modo de vida patriarcal. Es más, se ha llegado a escuchar: si el Papa fuera mujer el aborto sería ley. Ciertamente una meta lejana. Pero esta tendencia podría prometer acercarla mediante, por ejemplo, la incorporación de mujeres al sacerdocio y a las instancias de decisión del Estado Vaticano. Es cierto que leer sólo de este modo esa consigna del Encuentro Nacional de Mujeres de 2012 sería un olvido imperdonable de la ironía en que se sostiene. Pero a los efectos de estas líneas no interesa la consigna en sí misma (transitoria, como toda consigna), sino una posible lectura (quizás no la del Encuentro) que ella tolera, a saber: ese camino amarillo del progreso que se nos propone como una salida de emergencia a los males del patriarcado. Estaríamos entonces frente a un debilitamiento o crisis del patriarcado; el esperado síntoma sería ese lugar de poder ganado para las mujeres.
Aprender y enseñar a través de imágenes. Desafío educativo
Rigo, Daiana Yamila
El presente trabajo muestra la experiencia de la puesta en práctica de un diseño instructivo definido a partir del uso de recursos educativos icónicos con el objetivo de conocer cómo los alumnos valoran la realización de actividades académicas definidas a partir de imágenes, fotografías y obras de arte, e indagar la percepción de los estudiantes sobre las posibilidades que este medio ofrece para una comprensión y motivación mayor. La experiencia se desarrolla con alumnos de sexto grado, educación primaria, área Ciencias Sociales a través de dos actividades centrales. Los resultados revelan que el uso de la imagen como recurso didáctico debería ser tenido en cuenta como una estrategia de enseñanza-aprendizaje para planificar las tareas académicas.; This paper shows the experiences of the implementation of instructional design, defined from the use of iconic educational resources with the aim of knowing how students value the academic activities defined from images, pictures and artwork, as well as explore the perception of the students about the possibilities offered this medium for a greater understanding and motivation. The experience is developed with sixth graders, elementary education, social sciences area, through two core activities. The results reveal that the use of the image as a teaching resource should be considered as a teaching-learning strategy to plan academic tasks.
DNA Repair Activity of Ilex paraguariensis in Human Cells In Vitro
Erben, Melina; Poletta, Gisela Laura; Simoniello, Maria Fernanda
Yerba mate (Ilex paraguariensis) has been consumed as popular infusions in South America for centuries, with potential beneficial effects on health. The aim of this study was to evaluate yerba mate antioxidant properties in human leucocytes exposed in vitro to oxidative damage, using the Comet assay. Human cells were exposed to 10 μM H2O2 and then allowed to repair with increasing concentrations of two different yerba mate infusions: 10 μl/mL, 100 μl/mL and 1000 μl/mL. Damage Index (DI) and the percentage of damage reduction (%DR) were calculated. DI showed that both infusions produced similar protective effects (p > 0.05) and the %DR indicated a decreased in oxidative damage as infusion concentration increases (p < 0.05). The greatest protective effects were found using the highest concentration of mate (1000 μl/mL). Thus, we conclude that the regular ingestion of Ilex paraguariensis infusions could contribute to antioxidant defense on humans.; La yerba mate (Ilex paraguariensis) se consume como infusión popular en América del Sur desde hace siglos, con potenciales efectos beneficiosos sobre la salud. El objetivo de este estudio fue evaluar las propiedades antioxidantes de la yerba mate en leucocitos humanos expuestos in vitro a un daño oxidativo, utilizando el ensayo cometa. Células humanas fueron expuestas a 10 μM de H2O2 y luego reparadas con concentraciones crecientes de dos diferentes infusiones de yerba mate: 10, 100 y 1.000 μL/mL. Se calculó el índice de daño (DI) y el porcentaje de reducción de daño (% DR). El DI mostro que ambas infusiones producen efectos protectores similares (p > 0,05) y el % DR indicó una disminución en el daño oxidativo al aumentar la concentración de la infusión (p < 0,05). Los mayores efectos protectores fueron encontrados con la concentración más alta de mate (1.000 μl/mL). Por lo tanto, concluimos que la ingestión regular de infusiones de Ilex paraguariensis podría contribuir a la defensa antioxidante en seres humanos.
Comprehensive database on Induan (Lower Triassic) to Sinemurian (Lower Jurassic) marine bivalve genera and their paleobiogeographic record
Ros Franch, Sonia; Márquez Aliaga, Ana; Damborenea, Susana Ester
Marine bivalve genera that were described or mentioned for Triassic and Lower Jurassic deposits worldwide are reviewed in terms of their validity, stratigraphic range, paleogeographic distribution, paleoautoecology and shell mineralogy. Data were originally compiled at species level and are arranged systematically. A brief discussion for each genus includes synonymy, taxonomic status and included subgenera, as well as current uncertainties about their validity and range. The distribution of each genus is also shown on paleogeographic maps. Type species and first and last appearances of each genus are also mentioned. We recognize as valid 280 genera and their included subgenera, and we further discurss 148 genera (arranged alphabetically) which were mentioned for the study interval but are not included for different reasons. The purpose of this paper is to provide an updated critical assessment of all available basic information for each genus, in order to obtain a sound database to study the generic paleodiversity of marine bivalves in the time interval from Induan (Early Triassic) to Sinemurian (Early Jurassic). This was a critical time for bivalve evolution and diversification, which began with the recovery from the Permian-Triassic extinction and ended with the recovery from the Triassic-Jurassic extinction.
Biocatalysed acidification and metal leaching processes in sediments of polluted urban streams
Porzionato, Natalia Florencia; Candal, Roberto Jorge; Curutchet, Gustavo Andres
Sediments of fluvial streams are a sink for pollutants such as heavy metals and organic recalcitrant compounds. In anoxic conditions, sulphide generation and alkalinisation cause precipitation of heavy metals. The redox potential of the system could change to higher values, mainly owing to oxygen exposition generated by anthropogenic disturbances of the sediment such as dredging operations. Knowledge about the mechanisms involved is fundamental to assess the risk of acid generation and rise in heavy metals bioavailability. In this paper, the characterisation and assessment of acidification risk of sediments of a contaminated stream near Buenos Aires was carried out by static and kinetic assays. Speciation of heavy metals was determined after metal sequential extraction procedure. Also, re-suspension of sediments assay in batch mode, with and without Acidithiobacillus ferrooxidans inoculum, was carried out to assess the chemical changes that occur at oxygen exposure, verifying the acidification and heavy metal release processes.
