Estudios genético-poblacionales de Caiman latirostris (Reptilia, Alligatoridae) en Santa Fe, Argentina: una revisión a través del tiempo Amavet, Patricia Susana; Rosso, Daniel Esteban; Markariani, Rosa; Larriera, Alejandro Los estudios genéticos en Caiman latirostris (Yacaré overo) en Santa Fe, Argentina, comenzaron con un análisis citogenético en comparación con Caiman yacare. El cariotipo en ambas especies consistió de 42 cromosomas, con un patrón de bandas C difuso y un solo par de cromosomas con NOR. Debido a la falta de diferencias claras entre ambos cariotipos, decidimos usar marcadores moleculares en el análisis de esta especie. Cuatro isoenzimas: Esterasas, Isocitrato Dehidrogenasa, Malato Dehidrogenasa, y Superóxido Dismutasa se analizaron en animales provenientes de cuatro poblaciones santafesinas. En todos los casos se encontraron valores nulos de heterocigosis. Se analizaron 7 primers para RAPD y sólo 13.73 % de 233 marcadores analizados resultaron polimórficos. Los resultados para polimorfismos, heterocigosis y número medio de alelos por locus en las poblaciones fueron niveles bajos a intermedios. El análisis de AMOVA indicó que casi toda la variación existe dentro de las poblaciones, significando que varios alelos son compartidos entre las poblaciones. Debido a que los marcadores RAPD pueden ser menos eficaces en detectar variaciones que los microsatélites en poblaciones de cocodrilianos, en estos momentos estamos comenzando a utilizar esta técnica en el análisis poblacional. Hasta el momento se han amplificado positivamente cuatro primers, y detectamos indicios de la existencia de más de un padre en tres familias. Los datos genéticos de especies nativas son fundamentales para establecer y evaluar planes de manejo, y el análisis de variabilidad es básico para el conocimiento biológico de las especies, aportando a la sistemática, la ecología y la biodiversidad.

Comportamiento animal y evolución Vassallo, Aldo Iván El aprendizaje social de comportamientos es característico de la especie humana y está en la base de lo que llamamos cultura. ¿Existe, aunque más no fuera en forma rudimentaria, en los animales?

Synthesis and Characterization of Photoswitchable Fluorescent Silica Nanoparticles Fölling, Jonas; Polyakova, Svetlana; Belov, Vladimir; Van Blaaderen, Alfons; Bossi, Mariano Luis; Hell, Stefan W. We have designed and synthesized a new functional (amino reactive)highly efficient fluorescent molecular switch (FMS) with a photochromicdiarylethene and a rhodamine fluorescent dye. The reactive group in thisFMS -N-hydroxysuccinimide ester- allows selective labeling of aminocontaining molecules or other materials. In ethanolic solutions, thecompound displays a large fluorescent quantum yield of 52% and alarge fluorescence modulation ratio (94%) between two states that maybe interconverted withred and near-UV light. Silica nanoparticles incorporatingthe new FMS were prepared and characterized, and their spectroscopicand switching properties were also studied. The dye retained itsproperties after the incorporation into the silica, thereby allowing lightinducedreversible high modulation of the fluorescence signal of a singleparticle for up to 60 cycles, before undergoing irreversible photobleaching.Some applications of these particles in fluorescence microscopy arealso demonstrated. In particular, subdiffraction images of nanoparticleswere obtained, in the focal plane of a confocal microscope.

Temperature, conversion, and phase separation profiles during mold cure of a modified vinyl-ester resin Schroeder, Walter Fabian; Auad, M. L.; Soulé, Ezequiel Rodolfo In this work, morphological differences over the thickness of modified vinyl-ester (VE) samples are studied. A thermodynamic analysis based in the Flory-Rehner theory is proposed to evaluate the spinodal decomposition temperature evolution during the reaction. This model takes into account changes in (styrene-co-VE) copolymer composition and binary interaction parameters with conversion. Then, from the energy and mass balance equations, temperature and conversion profiles over the thickness as a function of reaction time are calculated. Combining these profiles with the proposed thermodynamic model, spinodal decomposition conversion graphs are constructed. To verify model predictions, a synthesized VE resin was modified with 7.5 wt% of poly(butadiene-co-acrylonitrile) vinyl terminated (VTBN) elastomer and then cured in molds of 3, 7, 12, and 20 mm thickness at 80°C. Fracture surfaces were observed by scanning electron microscopy showing morphological differences over thickness, which can be explained from the results obtained from the simulation.

Brain alterations in autoimmune and pharmacological models of diabetes mellitus: focus on hypothalamic-pituitary-adrenocortical axis disturbances Beauquis, Juan; Homo Delarche, Francoise; Revsin, Yanina; de Nicola, Alejandro Federico; Saravia, Flavia Eugenia Type 1 diabetes (T1D) is linked to an 'encephalopathy' explained by some features common to the aging process, degenerative and functional disorders of the central nervous system. In the present study we describe a manifest hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis in two different experimental mouse models of T1D including the pharmacological one induced by streptozotocin and the spontaneous NOD (nonobese diabetic mice). The high expression of hypothalamic hormones like oxytocin and vasopressin were part to this alteration, together with elevated adrenal glucocorticoids and prominent susceptibility to stress. In the hippocampus of diabetic animals a marked astrogliosis, often associated with neural damage, was present. Dentate gyrus neurogenesis was also affected by the disease: proliferation and differentiation measured by bromodeoxyuridine immunodetection were significantly reduced in both experimental models used. Several facts, including changes associated with chronic hyperglycemia, hyperstimulation of the HPA axis, increased levels of circulating glucocorticoids in combination with brain inflammation and low production of new neurons, contribute to emphasize the impact of diabetes on the central nervous system.

Adrenal hypersensitivity precedes chronic hypercoricism in streptozotocin-induced diabetes mice Revsin, Yanina; van Wijk, Diane; Saravia, Flavia Eugenia; Oitzl, Melly; de Nicola, Alejandro Federico; de Kloet, Edo Ronald Previous studies have demonstrated that type 1 diabetes is characterized by hypercorticism and lack of periodicity in adrenal hormone secretion. In the present study, we tested the hypothesis that hypercorticism is initiated by an enhanced release of ACTH leading subsequently to adrenocortical growth and increased output of adrenocortical hormones. To test this hypothesis, we used the streptozotocin (STZ)-induced diabetes mouse model and measured hypothalamic-pituitary-adrenal axis activity at different time points. The results showed that the expected rise in blood glucose levels induced by STZ treatment preceded the surge in corticosterone secretion, which took place 1 d after diabetes onset. Surprisingly, circulating ACTH levels were not increased and even below control levels until 1 d after diabetes onset and remained low until d 11 during hypercorticism. In response to ACTH (but not vasopressin), cultures of adrenal gland cells from 11-d diabetic mice secreted higher amounts of corticosterone than control cells. Real-time quantitative PCR revealed increased expression of melanocortin 2 and melanocortin 5 receptors in the adrenal glands at 2 and 11 d of STZ-induced diabetes. AVP mRNA expression in the paraventricular nucleus of the hypothalamus was increased, whereas hippocampal MR mRNA was decreased in 11-d diabetic animals. GR and CRH mRNAs remained unchanged in hippocampus and paraventricular nucleus of diabetic mice at all time points studied. These results suggest that sensitization of the adrenal glands to ACTH rather than an increase in circulating ACTH level is the primary event leading to hypercorticism in the STZ-induced diabetes mouse model.

Mating system, outcrossing distance effects and pollen availability in the wind-pollinated treeline species Polylepis australis BITT. (Rosaceae) Seltmann, Peggy; Cocucci, Andrea Aristides; Renison, Daniel; Cierjacks, Arne; Hensen, Isabell Fragmentation may negatively affect plant fitness through pollen limitation and increased levels of inbreeding. Effects of fragmentation may vary with regard to life form and breeding system, and few studies exist for wind- pollinated trees. We examined the effects of hand-selfing, varying outcrossing distances and pollen addition on seed mass and germination rate of Polylepis australis BITT. (Rosaceae), a wind-pollinated treeline species endemic to Argentina. We also investigated pollen germination on the stigma and pollen tube growth to determine compatibility resulting from selfing and outcrossing. Selfing reduced seed germination rates with significant differences between open pollination and outcrosses at 30km. In addition, we found a tendency for pollen germination and pollen tube growth to decrease following selfing. Between-fragment crosses resulted in a trend of higher reproductive out put than within- fragment crosses, whereas values were similar between open pollination and between-fragment crosses. Pollen addition did not increase reproductive success neither in small nor in larger fragments. Our results suggest that highly isolated P. australis forests have a potential for inbreeding depression through selfing and within-fragment crosses. However, the results also indicate that pollen flow between P. australis forest fragments is still effective at the current fragmentation level, counteracting negative effects on seed quality resulting from reproductive isolation.; Durch Habitatzerstörung und Fragmentierung isolierte und kleine Populationen leiden häufig unter erhöhter Inzuchtdepression und Pollenlimitierung, deren Ausmaß jedoch in Abhängigkeit von Lebensform und Fortpflanzungssystem variiert. In der vorliegenden Studie untersuchten wir den Einfluss von Hand-Selbstbestäubung, verschiedenen Kreuzungsdistanzen bis zu 30 km und Pollenzugabe auf Samenmasse und -keimung von Polylepis australis (Rosaceae), einer windbestäubten, in Argentinien endemischen Baumart der oberen Waldgrenze. Darüber hinaus analysierten wir den Einfluss von Selbst- und Fremdbestäubung auf Pollenkeimung und Pollenschlauchwachstum. Selbstbestäubung führte zu signifikant geringeren Keimraten im Vergleich zu natürlicher Bestäubung und Fremdbestäubung mit Pollen aus >30 km Distanz. Auch fanden wir eine Tendenz zur Reduktion von Pollenkeimung und Pollenschlauchwachstum nach Selbstbestäubung. Kreuzungen zwischen Fragmenten führten zu höherem Reproduktionserfolg als Kreuzungen innerhalb von Fragmenten, während der Reproduktionserfolg aus natürlicher Bestäubung und aus Kreuzungen zwischen Fragmenten vergleichbare Werte aufwies. Weder in kleinen noch in großen Populationen führte die Zugabe von Pollen zu einer Erhöhung des Reproduktionserfolges. Unsere Ergebnisse machen deutlich, dass zwar in stark isolierten P. australis Wäldern die Gefahr für Inzuchtdepression besteht, der nach wie vor effektive Pollen- und Genfluss zwischen Waldfragmenten von P. australis jedoch negativen Isolationseffekten entgegenwirkt.

Widespread inhibition proportional to excitation controls the gain of a leech behavioral circuit Baca, Serapio M.; Marin Burgin, Antonia; Wagenaar, Daniel A.; Kristan, William B. Changing gain in a neuronal system has important functional consequences, but the underlying mechanisms have been elusive. Models have suggested a variety of neuronal and systems properties to accomplish gain control. Here, we show that the gain of the neuronal network underlying local bending behavior in leeches depends on widespread inhibition. Using behavioral analysis, intracellular recordings, and voltage-sensitive dye imaging, we compared the effects of blocking just the known lateral inhibition with blocking all GABAergic inhibition. This revealed an additional source of inhibition, which was widespread and increased in proportion to increasing stimulus intensity. In a model of the input/output functions of the three-layered local bending network, we showed that inhibiting all interneurons in proportion to the stimulus strength produces the experimentally observed change in gain. This relatively simple mechanism for controlling behavioral gain could be prevalent in vertebrate as well as invertebrate nervous systems.

The axon-guidance roundabout gene alters the pace of the Drosophila circadian clock Berni, Jimena; Beckwith, Esteban Javier; Fernandez, María Paz; Ceriani, Maria Fernanda Great efforts have been directed to the dissection of the cell-autonomous circadian oscillator in Drosophila. However, less information is available regarding how this oscillator controls rhythmic rest-activity cycles. We have identified a viable allele of roundabout, robo(hy), where the period of locomotor activity is shortened. From its role in axon-pathfinding, we anticipated developmental defects in clock-relevant structures. However, robo(hy) produced minor defects in the architecture of the circuits essential for rhythmic behaviour. ROBO's presence within the circadian circuit strengthened the possibility of a novel role for ROBO at this postdevelopmental stage. Genetic interactions between pdf (01) and robo(hy) suggest that ROBO could alter the communication within different clusters of the circadian network, thus impinging on two basic properties, periodicity and/or rhythmicity. Early translocation of PERIOD to the nucleus in robo(hy) pacemaker cells indicated that shortened activity rhythms were derived from alterations in the molecular oscillator. Herein we present a mutation affecting clock function associated with a molecule involved in circuit assembly and maintenance.

The Lattice of Subvarieties of Monadic Lukasiewicz Algebras Abad, Manuel; Díaz Varela, José Patricio; Rueda, Laura Alicia; Suardíaz, Ana In this paper we describe the lattice of subvarieties of the variety ofmonadic Łukasiewicz-Moisil algebras. We then characterize all these subvarieties by means of identities.

Dictadura y desapariciones en Argentina: memoria, conocimiento y reconocimiento Crenzel, Emilio Ariel Este artículo examina los obstáculos novedosos que instaló el ejercicio sistemático de las desapariciones por parte del Estado Argentino desde el golpe militar de 1976 para la evocación de sus víctimas y para el conocimiento de la naturaleza de este crimen. Por un lado, en él se analiza como las desapariciones quebraron los marcos sociales básicos para evocarlas e integrarlas en un relato con sentido. Por otro lado, se expone, a partir del análisis de las principales denuncias durante la dictadura, como sus cualidades particulares tornaron profundamente heterogéneo el conocimiento y el reconocimiento de sus atributos aun entre las relaciones sociales de los desaparecidos y la militancia política dentro y fuera del país. El trabajo que aquí se presenta, se inscribe en el intento por pensar los dilemas y consecuencias específicas que las desapariciones plantearon para el ejercicio de la memoria y la producción de conocimiento sobre ellas en la sociedad argentina.

Ectomycorrhizal fungi associated with ponderosa pine and Douglas-fir: A comparison of species richness in native western North American forests and Patagonian plantations from Argentina Barroetaveña, Carolina; Cázares, E.; Rajchenberg, Mario The putative ectomycorrhizal fungal species registered from sporocarps associated with ponderosa pine and Douglas-fir forests in their natural range distribution (i.e., western Canada, USA and Mexico) and from plantations in south Argentina and other parts of the world are listed. One hundred and fifty seven taxa are reported for native ponderosa pine forests and 514 taxa for native Douglas-fir forests based on available literature and data bases. A small group of genera comprises a high proportion of the species richness for native Douglas fir (i.e., Cortinarius, Inocybe and Russula), while in native ponderosa pine the species richness is more evenly distributed among several genera. The comparison between ectomycorrhizal species richness associated with both trees in native forests and in Patagonia (Argentina) shows far fewer species in the latter, with 18 taxa for ponderosa pine and 15 for Douglas-fir. Epigeous species richness is clearly dominant in native Douglas fir while a more balanced relation epigeous/hypogeous richness is observed for native ponderosa pine; a similar trend was observed for Patagonian plantations. Most fungi in Patagonian Douglas fir plantations have not been recorded in plantations elsewhere, except Suillus lakei and Thelephora terrestris, and only 56% of the fungal taxa recorded in Douglas fir plantations around the world are known from native forests, the other taxa being new associations for this host, suggesting that new tree+ectomycorrhizal fungal taxa associations are favored in artificial situations as plantations.

Groundwater and soil chemistry changes under phreatophytic tree plantations Jobbagy Gampel, Esteban Gabriel; Jackson, Robert B. The onset of groundwater consumption by plants can initiate a pathway of chemical inputs from aquifers to ecosystems, typically absent in groundwater recharge areas. We explored this biogeochemical transfer and its influence on soils in phreatophytic eucalypt plantations and native grasslands of the Pampas (Argentina). Groundwater and soil chemical observations at three grassland/plantation pairs were complemented with more detailed analyses along a 400-m-long grassland-plantation transect. Although tree plantations showed a widespread and homogeneous salinization of groundwater and soils at all study sites, chemical contrasts between the plantation edge and core were evident along the study transect. Nonsalty, slightly acidic, bicarbonate-dominated waters in the grassland changed sharply within the plantation, with dissolved chloride, sulfate, calcium, and magnesium peaking at the plantation core (200 m away from the grassland) and dissolved sodium, carbonate, bicarbonate, and pH peaking toward the edge (0–50 m away from the grassland) and declining toward the core. In agreement with these differences, soil alkalinization was the strongest at the plantation edge but absent in the core. Groundwater flow simulations using FLOWNET suggested trajectories of increasing length and depth and older groundwater ages (confirmed by tritium analyses) toward the plantation core, explaining the hydrochemical contrasts within the plantation. Flow simulations and chloride mass balances suggested discharges of 250–500 mm yr−1 to the plantations. In our sites phreatophytic discharge controlled solute transfers from groundwater through (1) altered flow within the aquifer, affecting solute transport to the rooting zone, and (2) water uptake plus solute exclusion, concentrating solutes in the rooting zone. While the first mechanism may be restricted to the core of large phreatophytic areas, the second is likely to occur more generally in phreatophytic ecosystems.

Effect of Gelatin on Apple Juice Turbidity Benitez, Elisa Ines; Lozano, Jorge Enrique Clarification of apple juice by flocculation and precipitation with bentonite and gelatin is explained on a more systematic basis, essentially through the determination of turbidity and zeta-potential. Apple juice was also treated with Polyvinylpolypyrrolidone (PVPP) to remove total polyphenol. Gelatin-particle complex was evaluated as the increase in juice turbidity after the adding of tannic acid. The change of slope during Zeta potential determination indicated that electrostatic forces predominate at low gelatin content, and hydrophobic and hydrophilic interactions occur later at a higher gelatin content. Results also indicated that tannic acid test is useful for determining optimal gelatin concentration for clarification, as test was unaffected by soluble solids, acidity, or pectinase treatment. Gelatin consumption was mainly attributed to colloidal particles. Finally, results indicated that risk of haze by free gelatin in juice required at least 10 times more gelatin than the optimum dosage for clarification.

Polarimetric Observations of Hungaria Asteroids Gil Hutton, Ricardo Alfredo; Lazzaro, D.; Benavidez, P. Aims. We present the results of a polarimetric program at Complejo Astronómico El Leoncito (Casleo), San Juan, Argentina. The aim of this campaign is to estimate the polarimetric properties of asteroids belonging to the Hungaria dynamical group. Methods. The data were obtained with the Casprof polarimeter at the 2.15 m telescope. The Casprof polarimeter is a two-hole aperture polarimeter with rapid modulation. The campaign began in 2000, and data on a sample of 24 members of the Hungaria group were obtained. We use the slope - albedo or Pmin - albedo relationships to get polarimetric albedos for 18 of these objects. Results. Only two Xe-type objects, 434 Hungaria and 3447 Burkhalter, shown a polarimetric behavior compatible with a high albedo object. The A-type asteroid 1600 Vyssotsky has a polarimetric behavior similar to what was observed by Fornasier et al. (2006) for 863 Benkolea, and four objects show Pmin values consistent with dark surfaces.

Discovery of Rapid oscillations in HD 218994 Gonzalez, Jorge Federico; Hubrig, S.; Savanov, I. Asteroseismology has the potential to provide new insights into the physics of stellar interiors. Among the most promising objects that can be studied through this technique are the rapidly oscillating Ap (roAp) stars. These pulsate in high-overtone, low-degree, nonradial p-modes, with periods in the range 6-21 min. Our previous study (Hubrig et al., 2000) discussed the relationship between the roAp stars and the non-oscillating Ap (noAp) stars and concluded that the noAp stars are, in general, slightly more evolved than the roAp stars. The Ap Sr star HD 218994 was checked photometrically for the presence of rapid oscillations in the Cape Survey, but no oscillations have been detected by Martinez & Kurtz. This star was previously included in the sample of non-pulsating binary Ap stars studied by Hubrig et al. (2000). We have been granted one hour of UVES high time resolution observations of this star at ESO VLT on Cierro Paranal on November 15, 2006 and were able to obtain 15 spectra with exposure times of 3 min and a sampling of 3.7 min, taking into account the CCD readout time. To search for pulsational line variability, we calculated the average spectrum of the observed 15 spectra and subtracted it from the original spectra. In Fig. 1 we present the behaviour of the spectral profile of the Nd III line at {lambda} 6327 and its standard deviations. Similar variations were also found for the Pr III lines at {lambda} 6053 and {lambda} 6090. It was already shown in numerous studies that rare elements have higher amplitudes in roAp stars compared to lines of Fe-peak elements (e.g. Kurtz, Elkin & Mathys 2005). We also note that the mean RV for different elements is different, indicating the presence of chemical inhomogeneities on the stellar surface. Our analysis of RV variations of the Nd III line indicates two pulsation periods: one period of 5.1 min with an amplitude of 516 m/s and another one of 13.9 min and an amplitude of 497 m/s. It is very likely that one of these peaks is an alias. The amplitude spectrum of the radial velocity variations is presented in Fig. 2. We note that a longer time series with better temporal resolution is needed for a careful identification of the principal frequency and a search for the presence of other pulsation frequencies. To confirm the detected spectroscopic variation period, we searched for a periodicity in the photometric data using Hipparcos and ASAS photometric databases. Indeed, also the photometric data show a sinusoidal variation with a period identical to the spectroscopic period, P=5.1 min, and an amplitude of 0.005 mag. In Fig. 3 we present both the RV variations of the Nd III line and the ASAS light curve. The star HD 218994 becomes now the 36th star known to be a roAp star.

A multicoincidence study of ionic fragmentation of methyl tiocyanate, CH3SCN involving S 2p electrons Cortés, E.; Erben, Mauricio Federico; Gerones, Mariana; Romano, Rosana Mariel; Della Vedova, Carlos Omar We report a study of the photon impact excitation and dissociation dynamics of CH3SCN exited at the S 2p level by using synchrotron radiation. Within our knowledge ionic fragmentation of photon excited CH3SCN has not been previously described. The transitions observed in the TIY spectrum around the S 2p edge shows an excellent agreement with the optical oscillator strengths derived from electron energy loss spectra recorded under electric dipole dominated conditions.3SCN exited at the S 2p level by using synchrotron radiation. Within our knowledge ionic fragmentation of photon excited CH3SCN has not been previously described. The transitions observed in the TIY spectrum around the S 2p edge shows an excellent agreement with the optical oscillator strengths derived from electron energy loss spectra recorded under electric dipole dominated conditions.

Intensity ratios of H lines: Departures from the ideal conditions in the range of laser-induced breakdown spectroscopy experiments Cruzado, Alicia; Di Rocco, Hector Omar In the present paper we analyze the behavior of H line intensity ratios with electron density and electron temperature in intermediate-density plasmas. We analyze the influence on the line intensity ratios of (1) the departures from local thermodynamic equilibrium (LTE) of the level population ratios, (2) the plasma opacity, and (3) the lowering of the ionization potential. We look, particularly, at the lines Hα, Hβ, Hγ, and Hδ and the energy levels involved in the corresponding atomic transitions for their use as diagnostics in laser-induced breakdown spectroscopy (LIBS) experiments. One important conclusion is that, for typical values of the plasma dimension and the electron temperature taking place in LIBS, i.e., L = 1 mm and Te = 10 000 K, respectively, the intensity ratios Hβ/Hα, Hγ/Hα and Hδ/Hα depart from the ideal values by less than 10% in the interval 0.65 × 1014 part/cm3 ≤ NHI ≤ 3.6 × 1017 part/cm3, which means 1 × 1014 part/cm3 ≤ Ne, ≤ 1 × 10 16 part/cm3 for a gas of pure hydrogen. For higher densities, the departures from ideal conditions increase very quickly due to opacity effects.

Apoptosis y autofagia en las células estrelladas: Un nuevo potencial de los tocotrienoles en reducir la fibrogénesis asociada a la pancreatitis crónica Ropolo, Alejandro Javier; Vaccaro, Maria Ines Objetivo: la eliminación selectiva de células estrelladas pancreáticas (PSC) activadas a través de la inducción de su propia muerte programada es un objetivo de interés terapéutico en pacientes con pancreatitis crónica. En este trabajo se investigaron los efectos de los tocotrienoles sobre la muerte de PSC activadas. Materiales y métodos: PSC activadas y quiescentes, y células acinaresde páncreas de rata fueron tratadas con diferentes derivados de la vitamina E, α-tocoferol, α-, β-, γ- y δ-tocotrienoles, y una fracción rica en tocotrienoles de aceite de palma. Resultados: la fracción rica en tocotrienoles (TRF), pero no α-tocoferol, redujo la viabilidad de PSC activadas mediante el establecimiento de un programa de muerte, independiente de la regulación del ciclo celular. Las PSC activadas murieron por apoptosis, como fue indicado por un incremento en lafragmentación de ADN y la activación de caspasas, y a través de autofagia, como demostró la formación de vacuolas autofágicas y la acumulación de LC3-II. En contraste con los α-tocoferoles, la TRF causó una intensa y sostenida despolarización de la membrana mitocondrial y una gran liberación de citocromo c. La inhibición de caspasas con zVAD-fmk suprimió la apoptosis inducida por tocotrienoles pero amplificó la autofagia. Sin embargo, el bloqueo del poro de transición de permeabilidad mitocondrial con ciclosporina A abolió completamente los efectos letales de los tocotrienoles sobre las PSC. La inducción de muerte por tocotrienoles fue restringida a las PSC activadas, ya que no causó apoptosis ni en las PSC quiescentes ni en las células acinares. Conclusiones: los tocotrienoles gatillan selectivamente la muerte de PSC activadas actuando sobre el poro de transición de permeabilidad mitocondrial.Los hallazgos revelan un nuevo potencial para los tocotrienoles en reducir la fibrogénesis asociada a la pancreatitis crónica.

Estudio electroquímico del Ácido 3,4-Dihidroxifenilacético (DOPAC) adsorbido sobre oro; Electrochemical study of 3,4-Dihydroxyphenylacetic Acid (DOPAC) adsorbed on gold Esquenoni, Sylvia Matilde; Von Mengershausen, Alicia Elena; Sustersic, Maria Gisela El objetivo de este estudio es conocer el comportamiento del ácido 3,4 dihidroxifenilacético (DOPAC) como adsorbato y como reactivo electroquímico adsorbido sobre oro. Las características de la reacción redox del anillo catecol permite estudiar esta sustancia adsorbida a circuito abierto. El procedimiento consiste en las etapas de adsorción, enjuague con el electrolito y barridos de voltametría cíclica para determinar la cantidad de sustancia adsorbida y el comportamiento electroquímico de la misma. Se trabajó con dos celdas, una de adsorción y otra electroquímica, termostatizadas a 25°C. La adsorción del DOPAC es débil, consolidándose el enlace con el tiempo para formar una ligadura tipo σ. Se determina un área por molécula de 47 Å2, similar a la obtenida para la dopamina.; The objective of this study was to obtain knowledge on the behavior of acid 3,4 dihydroxyphenylacetic (DOPAC) as an adsorbate and electrochemical reagent adsorbed on gold. The redox reaction characteristic of the catechol ring allows the study of the substance adsorption under open circuit conditions. The step of the procedure include adsorption, rinsing with electrolyte, and making cyclic voltammetric scan to determine the amount of adsorbed substance and its electrochemical behavior. For this, two cells were employed, one for adsorption, and the other electrochemical, both were thermostatted at 25°C. The DOPAC adsorption is weak. The adsorption bound is strengthening with the time forming a σ bound. The area per molecule of 47 Å2 , very near of that of the dopamine is obtained.