Asymmetric synthesis of: Trans -4,5-disubstituted γ-butyrolactones involving a key allylboration step. First access to (-)-nicotlactone B and (-)-galbacin Henrion, S.; Macé, A.; Vallejos, Margarita; Roisnel, T.; Carboni, B.; Villalgordo, J.M.; Carreaux, Francois An efficient asymmetric synthesis of trans-4,5-disubstituted γ-butyrolactones from aldehydes and enantioenriched γ-carbamate alkenylboronates is reported. The cornerstone of this strategy is the implementation of sequential [3,3]-allyl cyanate rearrangement/allylboration/nucleophilic addition/cyclisation reactions. Diverse γ-butyrolactones such as the flavouring compounds, (+)-trans-whiskey lactone and (+)-trans-cognac lactone, as well as an advanced intermediate towards the first synthesis of natural products, (-)-nicotlactone B and (-)-galbacin, have thus been obtained.

Encapsulation of Compounds Biphenyls Into SBA-15: Synthesis of Composites for Application Guntero, Vanina Alejandra; Ferretti, Cristián Alejandro; Mancini, Pedro Maximo Emilio; Kneeteman, Maria Nelida Two novel hybrid mesoporous material BVA-SBA and BEG-SBA were designed and synthesized by a process assisted by microwave. The nanoparticles were studied by UV-vis and fluorescence spectroscopy, elemental analysis, nitrogen adsorption-desorption, RMN and FTIR. The results obtained indicates the successful immobilization of BVA and BEG in the mesoporous composite. These systems present the possibility of activating the release of the organic molecules encapsulated into SBA-15, depending on the liquid medium in which the composite are suspended.

Improving access to voting with optimized matchings Duran, Guillermo Alfredo; Giormenti, Mauro; Guajardo, Mario; Pinto, Pablo M.; Rey, Pablo A.; Stier Moses, Nicolás E. Research on political representation has traditionally focused on the design of electoral systems. Yet there is evidence that voting costs result in lower turnout and undermine voters’ confidence in the electoral system. Election administrators can selectively manipulate participation costs for different individuals and groups, leading to biased electoral outcomes. Quantifying the costs of voting and designing fair, transparent and efficient rules for voter assignment to polling stations are important for theoretical and practical reasons. Using analytical models, we quantify the differential costs of participation faced by voters, which we measure in terms of distance to polling stations and wait times to cast a vote. To estimate the model parameters, we use real-world data on the 2013 midterm elections in Argentina. The assignment produced by our model cut average voting time by more than 27%, underscoring the inefficiencies of the current method of alphabetical assignment. Our strategy generates better estimates of the role of geographical and temporal conditions on electoral outcomes.

Biología de nidificación de la abeja eusocial primitiva Augochlora phoemonoe (Halictidae); Nesting biology of the primitively eusocial bee Augochlora phoemonoe (Halicitdae) Dalmazzo, Maria de Los Milagros Se describe la biología de nidificación de la especie eusocial primitiva Augochlora phoemonoe(Halictidae) a partir de observaciones de nidos hallados en el campo y nidos artificiales mantenidos en laboratorio.La especie nidifica en madera en descomposición, aunque puede aceptar otro sustrato como el yeso. Se encontrarondos tipos de estructuras de nidificación: celdas apoyadas al sustrato sin cavidad circundante en campo yceldas dispuestas en forma de racimo rodeadas por una cavidad y sostenidas por un número variable de pilares enlaboratorio. Ambas estructuras presentaron un orificio de entrada rodeado por un anillo de partículas de maderacompactadas y un túnel no ramificado que conduce a las celdas. La hembra fundadora comienza el nido en formasolitaria. Hace primero el orificio de entrada y un túnel no ramificado, luego construye la o las primeras celdas.Las hembras hijas son las que continúan el proceso de construcción del nido durante la etapa social. Las abejascortan y separan con las mandíbulas pequeñas partículas de madera que son transportadas hacia otras partesdel nido donde las compactan utilizando los últimos tergos metasomales. Mediante estos procesos de remoción,transporte y compactación modifican el sustrato, excavan túneles y cavidades, tapizan superficies, y construyenpilares y celdas. Los hallazgos del presente estudio aportan caracteres para la clasificación de las estructuras denidificación para un futuro análisis filogenético dentro de Augochlorini.; The nesting biology of the primitively eusocial bee Augochlora phoemonoe (Halictidae) is described from nests collected in the field and nests constructed and maintained in the laboratory. This species nests in decaying wood, although it may accept plaster as nesting substrate. Two types of nest structure were found: cells laying on the substrate without a surrounding cavity in field conditions, and cells in a cluster supported by a variable number of pillars within a cavity in laboratory. Both structures had an entry hole surrounded by a compacted ring of sawdust, and an unbranched tunnel leading to the cells. The foundress female begins the nest solitarily. First she makes the entrance hole and the tunnel, and then she builds one or a few cells. The daughter females continue the construction of the nest during the social phase. Bees cut and separate the sawdust using the mandibles. Then, the bees transport the sawdust to other part of the nest and compact them using the latest metasomal terga. By the processes of removal, transport and compaction, the bees modify the substrate, excavate the tunnel and cavities, line the walls and construct pillars and cells. The findings of this study contribute with characters for a classification of nesting structures, and for further analysis of Augochlorini phylogeny.

Larval development of Aelurostrongylus abstrusus in experimentally infected Rumina decollata snails Cardillo, Natalia Marina; Ercole, Mariano Emmanuel; Fariña, Fernando Adrián; Pasqualetti, Mariana Ines; Loiza, Yanina Elizabeth; Pérez, Matías Gastón; Bonboni, Ayelen; Ribicich, Miriam Mabel Aelurostrongylus abstrusus is a lungworm distributed worldwide that affects wild and domestic cats, causing bronchopneumonia of varying intensity. Snails serve as intermediate hosts. The aim of the present study was to assess the larval development of A. abstrusus in R. decollata snails and to investigate its potential as an intermediate host. For this purpose, first-stage larvae (L1) of A. abstrusus were obtained from the faeces of naturally infected cats. Doses of 500 L1/snail were given to 24 R. decollata snails, placed on the soil of the breeder chamber, and maintained under laboratory conditions. Three snails were killed at 8, 10, 12, 16, 22, 26, 45 and 55 days post-infection (dpi), and the muscular foot and visceral body were separately digested by an artificial digestion technique. The morphometric parameters of different larval stages were recorded. The mean number of larvae reaching the infective stage at the end of the study (L3) was 262 larvae/snail. The greatest development to L3 was recorded from days16 to 55 pi, during which the isolation was maximum. A. Abstrusus L3 were isolated from the viscera, but isolation from the snail foot was significantly higher. Our results showed for the first time the ability of A. Abstrusus larvae to develop in R. decollata, thus serving as a potential intermediate host.

Sub-ångström cryo-EM structure of a prion protofibril reveals a polar clasp Gallagher Jones, Marcus; Glynn, Calina; Boyer, David R.; Martynowycz, Michael W.; Hernandez, Evelyn; Miao, Jennifer; Zee, Chih Te; Novikova, Irina V.; Goldschmidt, Lukasz; Mc Farlane, Heather T.; Helguera, Gustavo Fernando; Evans, James E.; Sawaya, Michael R.; Cascio, Duilio; Eisenberg, David S.; Gonen, Tamir; Rodriguez, Jose A. The atomic structure of the infectious, protease-resistant, β-sheet-rich and fibrillar mammalian prion remains unknown. Through the cryo-EM method MicroED, we reveal the sub-ångström-resolution structure of a protofibril formed by a wild-type segment from the β2–α2 loop of the bank vole prion protein. The structure of this protofibril reveals a stabilizing network of hydrogen bonds that link polar zippers within a sheet, producing motifs we have named ‘polar clasps’.

Breeding strategies in Melilotus albus Desr., a salt-tolerant forage legume Zabala, Juan Marcelo; Marinoni, Lorena del Rosario; Giavedoni, Julio Alberto; Schrauf, Gustavo Enrique Melilotus albus Desr. is recognized as one of the species with greatest potential as a forage source for ruminants in saline rangelands. The objectives of the current research were threefold: (1) to estimate heritability and genetic correlation of traits associated with winter forage production and regrowth capacity in M. albus prebreeding material, as measured in spaced plants grown in a nonsaline environment; (2) to evaluate winter forage production of a selected population grown in plots at sites with contrasting soil salinities; and (3) to evaluate the agronomic performance of blended (mixed) populations and monocultures of M. albus grown in plots. Results indicated presence of genetic variability associated with winter production and regrowth capacity in a prebreeding population selected for one trait, viz. late flowering. Results also showed that selection in a nonsaline environment did not modify the relative salinity tolerance of M. albus populations. Finally, varietal mixtures (blends) of two selected populations showed a slight increase in and more seasonally balanced dry matter (DM) yield than monocultures. Mixtures combined favorable characteristics from the two selected populations (i.e., highest winter forage production, as expressed in the SP1 population, and highest regrowth capacity, as expressed in the SP2 population). Furthermore, results indicated that M. albus genotypes naturalized in Argentina could be used as genetic resources for sweet clover breeding for saline environments and that alternative breeding approaches could improve forage productivity in saline environments.

Diffusion of Water and Electrolytes in Mesoporous Silica with a Wide Range of Pore Sizes Martínez Casillas, Diana Cristina; Longinotti, María Paula; Bruno, Mariano Martín; Vaca Chávez Fornasero, Fabián; Acosta, Rodolfo Héctor; Corti, Horacio Roberto The diffusion of alkaline chlorides (LiCl, KCl, and CsCl) and water in mesoporous silica samples with pore sizes covering the range from micropores (2 nm) up to mesopores larger than 30 nm have been measured by resorting to a simple diffusional technique in the case of electrolytes and 1H NMR in the case of water. The morphology of the silica samples varies from a microporous structure, an interconnected network of pores, and typical mesoporous materials with ink-bottle pores, with increasing pore size. The release of electrolytes from the silica as a function of time exhibits two differentiated regimes, at short and long times, which correlates quite well with the size of the pores and that of necks of the pores, respectively. The diffusion of water inside the pores follows the same trend with pore size that the diffusion of electrolytes, indicating a coupling between the ions and water diffusional mobilities. The tortuosity effect on the diffusion of all studied electrolytes and water shows a monotonic slight increase with decreasing diameter for pores larger than 5 nm, while the tortuosity factor increases markedly for smaller pores. In microporous and mesoporous silica with pore sizes below 10 nm, the tortuosity factor of Li+ ion is much larger than those for K+ and Cs+ ions, since its diffusion is hindered by a stronger electrostatic interaction with the ionizable silanol groups on the pore wall; and also larger than that for water diffusion which it is retarded by a weaker hydrogen bond interaction with the silanol groups. The differences in tortuosity factors among alkaline chlorides and water become negligible for pore sizes larger than 10 nm. The spin-lattice relaxation time measurements of 1H-water and Li+ ions confirm this behavior.

The pregnane X receptor (PXR) and the nuclear receptor corepressor 2 (NCoR2) modulate cell growth in head and neck squamous cell carcinoma Rigalli, Juan Pablo; Reichel, Matthias; Reuter, Tasmin; Tocchetti, Guillermo Nicolás; Dyckhoff, Gerhard; Herold Mende, Christel; Theile, Dirk; Weiss, Johanna Head and neck squamous cell carcinoma (HNSCC) is the sixth most frequent cancer worldwide. The pregnane X receptor (PXR) is a nuclear receptor regulating several target genes associated with cancer malignancy. We here demonstrated a significant effect of PXR on HNSCC cell growth, as evidenced in PXR knock-down experiments. PXR transcriptional activity is more importantly regulated by the presence of coactivators and corepressors than by PXR protein expression. To date, there is scarce information on the regulation of PXR in HNSCC and on its role in the pathogenesis of this disease. Coactivator and corepressor expression was screened through qRT-PCR in 8 HNSCC cell lines and correlated to PXR activity, determined by using a reporter gene assay. All cell lines considerably expressed all the cofactors assessed. PXR activity negatively correlated with nuclear receptor corepressor 2 (NCoR2) expression, indicating a major role of this corepressor in PXR modulation and suggesting its potential as a surrogate for PXR activity in HNSCC. To test the association of NCoR2 with the malignant phenotype, a subset of three cell lines was transfected with an over-expression plasmid for this corepressor. Subsequently, cell growth and chemoresistance assays were performed. To elucidate the mechanisms underlying NCoR2 effects on cell growth, caspase 3/7 activity and protein levels of cleaved caspase 3 and PARP were evaluated. In HNO97 cells, NCoR2 over-expression decreased cell growth, chemoresistance and increased cleaved caspase 3 levels, caspase activity and cleaved PARP levels. On the contrary, in HNO124 and HNO210 cells, NCoR2 over-expression increased cell growth, drug resistance and decreased cleaved caspase 3 levels, caspase activity and cleaved PARP levels. In conclusion, we demonstrated a role of PXR and NCoR2 in the modulation of cell growth in HNSCC. This may contribute to a better understanding of the highly variable HNSCC therapeutic response.

La potencia de los feminismos latinoamericanos para una ruptura epistemológica con el universalismo eurocéntrico del feminismo hegemónico. Críticas desde el margen Parra, Valeria Fabiana Frente al feminismo eurocéntrico hegemónico -que con sus pretensiones de universalidad invisibiliza a las mujeres que no pertenecen a un sistema de género blanco, binario y burgués-el feminismo latinoamericano: decolonial, materialista, y diverso, se nutre de epistemologías “otras” para construir un conocimiento situado desde las experiencias de vida de las propias mujeres subalternas: indígenas, campesinas, afrodescendientes, migrantes, lesbianas, pobres, mestizas. Excluidas y silenciadas por las demandas de un feminismo que no comprende al género como parte de un entramado complejo en el que la combinación e interseccionalidad de determinaciones vinculadas a la clase, la elección sexual, la pertenencia geopolítica, étnica y cultural, son fundamentales para el estatuto de lxs sujetxs. Ante este panorama, la tarea actual del feminismo debe ser la de ampliar voces y miradas. A lo largo de este trabajo, presentaré argumentos para mostrar que tal propósito puede lograrse desde una perspectiva feminista latinoamericana y decolonial porque la crítica realizada desde el margen posibilita interpelar la hegemonía y visibilizar la alteridad. Lo cual constituye una verdadera ruptura epistemológica.; Face o feminismo hegemônico eurocêntrico–que com suas pretensões de universalidade invisibiliza as mulheres que não pertencem a um sistema de gênero branco, binário e burguês–o feminismo latino-americano: decolonial, materialista e diversificado, nutre-se por epistemologias "outras" para construir um conhecimento localizado a partir das experiências de vida das próprias mulheres subalternas: indígenas, camponeses, afrodescendentes, migrantes, lésbicas, pobres, mestiças. Excluídas e silenciadas pelas exigências de um feminismo que não compreende o gênero como parte de um quadro complexo em que a combinação e a interseção de determinações ligadas à classe, escolha sexual, pertença geopolítica, étnica e cultural são fundamentais para a estatuto dxs sujeitxs. Dado esse panorama, a atual tarefa do feminismo deve ser expandir vozes e olhadas. Ao longo deste trabalho, apresentarei argumentos para mostrar que tal propósito pode ser alcançado a partir de uma perspetiva feminista latino-americana e decolonial porque a crítica feita a partir da margem permite desafiar a hegemonia e tornar visível a alteridade. O que constitui uma verdadeira ruptura epistemológica.

Fire effects on the soil seed bank and post-fire resilience of a semi-arid shrubland in central Argentina Lipoma, Maria Lucrecia; Funes, Guillermo; Díaz, Sandra Myrna Soil seed bank is an important source of resilience of plant communities who suffered disturbances. We analysed the effect of an intense fire in the soil seed bank of a semi-arid shrubland of Córdoba Argentina. We asked if the fire affected seed abundance, floristic and functional composition of the soil seed bank at two different layers (0–5 cm and 5–10 cm), and if fire could compromise the role of the soil seed bank as a source of resilience for the vegetation. We collected soil samples from a burned site and from a control site that had not burned. Samples were installed in a greenhouse under controlled conditions. During 12 months, we recorded all germinated seedlings. We compare soil seed bank with pre-fire vegetation in terms of floristic and functional composition. The high-intensity fire deeply affected the abundance of seeds in the soil, but it did not affect its floristic or functional composition. Floristic and functional composition of soil seed banks – at burned and unburned sites- differed markedly from that of the pre-fire vegetation, although a previous study at the same site indicated high resilience after fire of this plant community. Our results indicate that resilience of this system is not strongly dependent on direct germination from seeds buried in the soil. Other sources of resilience, like colonization from neighbouring vegetation patches and resprouting from underground organs appear to gain relevance after an intense fire.

Preparation of Lignosulfonate-Based Carbon Foams by Pyrolysis and Their Use in the Microencapsulation of a Phase Change Material Palazzolo, Martín Alejandro; Dourges, Marie Anne; Magueresse, Anthony; Glouannec, Patrick; Maheo, Laurent; Deleuze, Hervé Currently, further research on the valorization of lignin is needed to shift biorefineries from a conceptual basis to profitable practice. Providing global warming is a major concern as well, the use of lignin as the sole precursor to elaborate materials with thermal energy storage (TES) applications is especially welcomed in the search for new sustainable solutions. To this end, the preparation of on-demand macroporous carbon foams from calcium lignosulfonate (CaLS) by pyrolysis is described herein, and their capability to microencapsulate phase change materials (PCMs) dedicated to the passive refrigeration of buildings by TES is further assessed as a proof of concept. The as-produced CaLS-based foams were found to be efficient containers for this purpose, displaying any appreciable leakage of PCMs. Furthermore, the thermal properties of the final materials were satisfactory as well, showing that the support does not affect the PCM performance negatively. Considering the process to produce such materials is not only straightforward but also relies on an inexpensive, widely available carbon precursor, it is expected that it serves as a starting point for pilot studies in TES projects.

Nanosilver toxicity in gills of a neotropical fish: Metal accumulation, oxidative stress, histopathology and other physiological effects Ale, Analía; Bacchetta, Carla; Rossi, Andrea Silvana; Galdopórpora, Juan Manuel; Desimone, Martín Federico; de la Torre, Fernando Roman; Gervasio, Susana Graciela; Cazenave, Jimena The widespread and increasing use of silver nanoparticles (AgNP) as biocide results in an unknown release into the aquatic environment. In order to contribute to the understanding of their potential toxicity, the aim of this study was to analyze branchial multiple biomarkers on the neotropical fish Prochilodus lineatus. We exposed fish to sublethal AgNP concentrations: 0 (control), 2.5 and 25.0 µg L−1. After 5 and 15 days, we analyzed in gills total Ag accumulation, oxidative stress markers (antioxidant enzymes, lipid peroxidation and antioxidant capacity against peroxyl radicals), aspartate and alanine aminotransferases activities (ALT, AST) and histopathologies (morphometric analysis, proportion of the secondary lamellae available for gas exchange, reaction indexes, and organ index -Igills-) that included mucus cell count (MCc). The Ag accumulation after 15 days was five times higher than after 5 days in the case of 25.0 μg AgNP L−1-exposure. Regarding oxidative stress, all enzymes activities were inhibited after 5 days at both AgNP concentrations. ALT activity decreased and a reduction in the antioxidant capacity was evidenced after 2.5 µg AgNP L−1 and 15 days. LPO levels and AST activity increased after the highest time of exposure and AgNP concentration, and the same occurred with Igills. MCc increased after 15 days at both AgNP concentrations. The results confirmed that the presence of low AgNP concentrations, in short and subchronic exposures, generates alterations in stress biomarkers and in the structure of this vital organ that are the gills.

The significance of climate in the pollinator dynamics of a tropical agroforestry system Arnold, S.E.J.; Bridgemohan, P.; Perry, G.B.; Spinelli, Gustavo Ricardo; Pierre, B.; Murray, Federico; Haughton, C.; Dockery, O.; Grey, L.; Murphy, S.T.; Belmain, S.R.; Stevenson, P.C. Even though many globally important tropical agroforestry crops are partially or completely dependent on insect pollination, the conditions influencing pollinator abundance in these systems are often incompletely understood. This is particularly the case for cocoa midges (Diptera: Ceratopogonidae), which are essential for cocoa pollination and thus yield, but agro-ecological management frequently neglects them. We report the first assessment of cocoa midge population dynamics from two Caribbean countries across a full year, and relate this to seasonal climate variables. We used static suction traps along transects to sample insects monthly, from six cocoa farms across three Caribbean islands, with a particular focus on known pollinators of cocoa. A total of over 87,000 insects were captured, including more than 1800 cocoa midges. Midges were present in all months of the survey and on all sites, but typically comprised less than 2% of the total insects caught. At least twelve different species of cocoa midges were identified from this survey. The previous month's rainfall positively predicted cocoa midge absolute abundance and further analysis also revealed a relationship between rainfall and relative midge abundance. In particular, during drought periods, midge numbers were very low, consistent with their larval ecology. Humidity and mean daily maximum and minimum temperatures did not relate to midge abundance. Rainfall negatively influenced the Shannon-Weaver index. The findings highlight the possible threat of droughts to cocoa pollination services and the importance of proactive farm management to support them.

Against Moral Purism; Contra el purismo moral García Gibson, Francisco Moral purism is the view that doing evil is never allowed, even as a means to prevent a greater evil. This article assesses two main versions of moral purism and shows that they are implausible. The first version claims that it is always impermissible to choose an option that results in a bad states of affairs, while the second version claims that it is always impermissible to choose an option that is wrong, even if it is only prima facie wrong. I contend that both versions are incomplete, in the sense that they are unable to provide practical guidance for cases in which all available options result in bad states of affairs, or in which all available options are prima facie wrong.; El purismo moral es la perspectiva según la cual hacer el mal no está permitido nunca, ni siquiera como un medio para prevenir un mal mayor. Este artículo evalúa dos versiones principales del purismo moral y muestra que ellas son imposibles. La primera versión afirma que es siempre impermisible escoger una opción que resulte en malos estados de cosas, mientras que la segunda versión afirma que es siempre impermisible escoger una opción que está mal, incluso su está tan solo prima facie mal. Yo sostengo que ambas versiones son incompletas en el sentido de que son incapaces de proveer una guía práctica para los casos en los que todas las opciones disponibles resultan en malos estados de cosas o en los que todas las opciones disponibles son prima facie malas.

Differential effects of AMP-activated protein kinase in isolated rat atria subjected to simulated ischemia–reperfusion depending on the energetic substrates available Hermann, Romina; Mestre Cordero, Victoria Evangelina; Fernández Pazos, María de las Mercedes; Reznik, Federico Joaquin; Vélez, Débora Elisabet; Savino, Enrique Alberto; Marina Prendes, María Gabriela; Varela, Alicia AMP-activated protein kinase (AMPK) is a serine–threonine kinase that functions primarily as a metabolic sensor to coordinate anabolic and catabolic processes in the cell, via phosphorylation of multiple proteins involved in metabolic pathways, aimed to re-establish energy homeostasis at a cell-autonomous level. Myocardial ischemia and reperfusion represents a metabolic stress situation for myocytes. Whether AMPK plays a critical role in the metabolic and functional responses involved in these conditions remains uncertain. In this study, in order to gain a deeper insight into the role of endogenous AMPK activation during myocardial ischemia and reperfusion, we explored the effects of the pharmacological inhibition of AMPK on contractile function rat, contractile reserve, tissue lactate production, tissue ATP content, and cellular viability. For this aim, isolated atria subjected to simulated 75 min ischemia–75 min reperfusion (Is-Rs) in the presence or absence of the pharmacological inhibitor of AMPK (compound C) were used. Since in most clinical situations of ischemia–reperfusion the heart is exposed to high levels of fatty acids, the influence of palmitate present in the incubation medium was also investigated. The present results suggest that AMPK activity significantly increases during Is, remaining activated during Rs. The results support that intrinsic activation of AMPK has functional protective effects in the reperfused atria when glucose is the only available energetic substrate whereas it is deleterious when palmitate is also available. Cellular viability was not affected by either of these conditions.

Heterochromatin protein (HP)1γ is not only in the nucleus but also in the cytoplasm interacting with actin in both cell compartments Charó, Nancy Lorena; Galigniana, Natalia Maricel; Piwien Pilipuk, Graciela Confocal and electron microscopy images, and WB analysis of cellular fractions revealed that HP1γ is in the nucleus but also in the cytoplasm of C2C12 myoblasts, myotubes, skeletal and cardiac muscles, N2a, HeLa and HEK293T cells. Signal specificity was tested with different antibodies and by HP1γ knockdown. Leptomycin B treatment of myoblasts increased nuclear HP1γ suggesting that its nuclear export is Crm-1-dependent. HP1γ exhibited a filamentous pattern of staining partially co-localizing with actin in the cytoplasm of myotubes and myofibrils. Immunoelectron microscopic analysis showed high-density immunogold particles that correspond to HP1γ localized to the Z-disk and A-band of the sarcomere of skeletal muscle. HP1γ partially co-localized with actin in C2C12 myotubes and murine myofibrils. Importantly, actin co-immunoprecipitated with HP1γ in the nuclear and cytosolic fractions of myoblasts. Actin co-immunoprecipitated with HP1γ in myoblasts incubated in the absence or presence of the actin depolymerizing agent cytochalasin D, suggesting that HP1γ may interact with G-and F-actin. In the cytoplasm, HP1γ was associated to the perinuclear actin cap that controls nuclear shape and position. In the nucleus, re-ChIP assays showed that HP1γ-actin associates to the promoter and transcribed regions of the house keeping gene GAPDH, suggesting that HP1γ may function as a scaffold protein for the recruitment of actin to control gene expression. When HP1γ was knocked-down, myoblasts were unable to differentiate or originated thin myotubes. In summary, HP1γ is present in the nucleus and the cytoplasm interacting with actin, a protein complex that may exert different functions depending on its subcellular localization.

Reciprocal interactions between a facilitator, natives, and exotics in tropical alpine plant communities Llambí, Luis D.; Hupp, Nicole; Sáez, Agustín; Callaway, Ragan Facilitation by nurse plants has received considerable attention, but the feedback effects of beneficiaries on the benefactor fitness remain comparatively unexplored. In particular, to our knowledge there have been no studies of feedback effects of exotic species on nurse plants. Furthermore, there have been few studies of how exotic plants interact with native beneficiaries, potentially generating indirect effects on the nurse. Here, through spatial association analyses, we estimate the reciprocal interactions between the cushion nurse-plant Arenaria musciformis, native beneficiaries, and the dominant exotic Rumex acetosella (a fast growing heliophile species) in a tropical alpine ecosystem of the Venezuelan Andes, locally known as páramos. We recorded the density of natives and the exotic within Arenaria cushions and in paired open areas at three sites and calculated Relative Interaction Indices (RII) to explore the effects of the cushion. Then, we analyzed the feedback effects of Rumex and the natives on the density of flowers produced by Arenaria. Finally, we analyzed how Rumex abundance is related to the abundance of native species inside and outside cushions. RIIs indicated a facilitative effect of cushions on the abundance of native plants, but no effect on Rumex. We found a negative relationship between the density of natives and cushion flower density, but no such relationship for Rumex. However, at high densities, Rumex was negatively correlated with the abundance of the natives both inside and outside of cushions. Our results suggest the possibility of complex reciprocal interactions between nurses, natives and exotics, and that native and exotic plants can differ in their feedback effects on nurse cushions. Native plants appeared to be facilitated by cushions and then develop a parasitic relationship with their nurses. In contrast, the exotic Rumex had a neutral interaction with the nurse, but competitive effects on the native beneficiary community, which could indirectly modulate the feedback effects of natives on the nurse. These results highlight the importance of analyzing direct and indirect reciprocal interactions and the impacts of exotic invaders for understanding alpine community assembly.

Structural and electronic properties of Al-doped ZnO semiconductor nanopowders: Interplay between XRD and PALS experiments and first-principles/DFT modeling Damonte, Laura Cristina; Darriba, German Nicolas; Rentería, Mario A combined experimental and novel theoretical ab initio structural and electronic study was performed in order to characterize ZnO semiconductor nanopowders doped with Al atoms. For this, powder mixtures of ZnO and metallic Al in adequate proportions yielding different contents of Al (5, 10, and 30 at. %) were prepared by mechanical milling. The systems were characterized by X-ray diffraction and positron annihilation lifetime spectroscopy measurements. Additionally, combining two first-principles methods based on the Density Functional Theory (DFT) we calculated the final equilibrium structures for different concentrations of Al dopants and Zn vacancies in ZnO, predicting afterwards the characteristic positron annihilation lifetimes at these equilibrium structures. In addition to the structural relaxations, the ab initio predictions of the electronic properties in the studied systems help us to understand deeper the origin and characteristics of different positrons traps. This experimental and ab initio/DFT combined study allows to verify the dopant incorporation into the ZnO wurtzite structure and to extract the maximum information from the experimental data, giving an insight into the different defect complexes and their influence in the structural and electrical properties.

Pattern formation mechanisms in sphere-forming diblock copolymer thin films Gomez, Leopoldo Raimundo; García, Nicolás A.; Register, Richard A.; Vega, Daniel Alberto The order–disorder transition of a sphere-forming block copolymer thin film was numerically stud-ied through a Cahn–Hilliard model. Simulations show that the fundamental mechanisms of patternformation are spinodal decomposition and nucleation and growth. The range of validity of each re-laxation process is controlled by the spinodal and order–disorder temperatures. The initial stagesof spinodal decomposition are well approximated by a linear analysis of the evolution equation ofthe system. In the metastable region, the critical size for nucleation diverges upon approaching theorder–disorder transition, and reduces to the size of a single domain as the spinodal is approached.Grain boundaries and topological defects inhibit the formation of superheated phases above the order–disorder temperature. The numerical results are in good qualitative agreement with experimental dataon sphere-forming diblock copolymer thin films.