Descripción: Oxidative stress plays a critical role in the pathogenesis of diabetes, hypertension and atherosclerosis. Some authors reported that fat accumulation correlates to systemic oxidative stress in humans and mice, but the relationship of lipid production and oxidative metabolism is still unclear. In our laboratory we used 3T3-L1 preadipocytes, which are able to differentiate into mature adipocytes and accumulate lipids, as obesity model. We showed that intracellular reactive oxygen species (ROS) and antioxidant enzymes superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities increased in parallel with fat accumulation. Meanwhile N-acetylcysteine (NAC), a well known antioxidant and Glutathione (GSH) precursor, inhibited ROS levels as well as fat accumulation in a concentration-dependent manner. NAC also inhibited both adipogenic transcription factors CCAAT/enhancer binding protein beta (C/EBP) and peroxisomal proliferator activated receptor gamma (PPAR β) expression; we suggested that intracellular GSH content could be responsible for these effects. © 2011 by the authors; licensee MDPI, Basel, Switzerland.

Descripción: A nan-nofossil association corresponding to Zone NJ20b was defined in the rhythmically interbedded limestones and marls of the Los Catutos Member, Vaca Muerta Formation. It confirmed the Late Middle Tithonian age, previously assigned on the basis of ammonites, to the beds which crop out in the locality of Zapala, Neuquén Province, Neuquén Basin. The stratigraphical resolution of the nannoflora was no better than that of the ammonite fauna, but a good correlation between zones can be established. This represents a powerful and useful tool for future biostratigraphical studies in the Neuquén Basin. On the basis of the ammonite and nannofossil zones, a period of 1 my was estimated for the deposition of the 25 m thick sequence of limestones and marls. From these data a high sedimentation rate (5 m/ka on average) was calculated. As a consequence, the duration of the individual limestone-marl cycles is about 20 ka on average, in good agreement with the precession period of the earth axis. Thus, rhythmic changes in sedimentation would be related to climatic changes driven by orbital forcing. © 1999 Asociacián Gcológica.

Descripción: Calcareouos nannofosils, duration and origin of limestone-marl cycles (Late Jurassic, Neuquén Basin). A nannofossil association corresponding to Zone NJ20b was defined in the rhythmically interbedded limestones and marls of the Los Catutos Member, Vaca Muerta Formation. It confirmed the Late Middle Tithonian age, previously assigned on the basis of ammonites, to the beds which crop out in the locality of Zapala, Neuquén Province, Neuquén Basin. The stratigraphical resolution of the nannoflora was no better than that of the ammonite fauna, but a good correlation between zones can be established. This represents a powerful and useful tool for future biostratigraphical studies in the Neuquén Basin. On the basis of the ammonite and nannofossil zones, a period of 1 my was estimated for the deposition of the 25 m thick sequence of limestones and marls. From these data a high sedimentation rate (5 m/ka on average) was calculated. As a consequence, the duration of the individual limestone-marl cycles is about 20 ka on average, in good agreement with the precession period of the earth axis. Thus, rhythmic changes in sedimentation would be related to climatic changes driven by orbital forcing. © 1999 Asociación Geológica Argentina.

Descripción: The recent development of table top extreme ultraviolet (EUV) lasers have enabled new applications that so far were restricted to the use of large facilities. These compact sources bring now to the laboratory environment the capabilities that will allow a broader application of techniques related to nanotechnology and nanofabrication. In this paper we review the advances in the utilization of EUV lasers in nanopatterning. In particular we show results of the nanopatterning using a table-top capillary discharge laser producing 0.12-mJ laser pulses with 1.2-ns time duration at a wavelength λ = 46.9 nm. The nanopatterning was realized by interferometric lithography using a Lloyd's mirror interferometer. Two standard photoresists were used in this work, polymethyl methacrylate (PMMA) and hydrogen silsesquioxane (HSQ). Pillars with a full width half maximum (FWHM) diameter of 60 nm and holes with FWHM diameter of 130 nm were obtained over areas in excess of 500×500 μm2. © 2008 Versita Warsaw and Springer-Verlag Berlin Heidelberg.

Descripción: • Background and Aims: Trees with a partial leaf-shedding pattern and other morphological features a priori considered intermediate between those of the deciduous Nothofagus antarctica (G. Forster) Oersted and the evergreen N. dombeyi (Mirb.) Oersted (Nothofagaceae) were found in natural stands. The hybridization between a deciduous and an evergreen species of Nothofagus has not been reported so far in natural communities. • Methods: The putative hybrids and the two presumed parental species were compared using 14 enzyme systems as well as shoot, leaf and reproductive morphology. • Key Results: Six enzyme systems showed good resolution (MDH-B, IDH, SKDH, 6-PGDH, GOT and PGI) and in four of them (PGI, MDH-B, SKDH and 6-PGDH) the putative hybrids showed intermediate zymogram patterns between N. antarctica and N. dombeyi. Both principal coordinates analysis on isozyme data and principal components analysis (PCA) on quantitative morphological traits of shoots and leaves separated both parental species and located the putative hybrids closer to N. antarctica than to N. dombeyi. In the PCA, the number of basal cataphylls and the length:width ratio of leaves were the variables most discriminating among shoots of the three entities. The putative hybrids were intermediate between both species regarding leaf vernation, outline and venation, variation in leaf shape (length/width) with position on the parent shoot and in staminate inflorescence and cupule morphology. For other morphological traits, the putative hybrids resembled one of the parental species or differed from both species (e.g. valve morphology). • Conclusions: Isoenzymatic and morphological data sets support the idea of the hybrid nature (probably F 1 generation) of the semi-deciduous trees found. Nothofagus antarctica and N. dombeyi are probably more closely related than previously assumed. The relevance of pollen type in revealing evolutionary relationships between Nothofagus species is supported, and that of leaf-shedding pattern is rejected. © 2004 Annals of Botany Company.

Descripción: The principal agents of Fusarium head blight in the main cropping area of Argentina were investigated in heavily infected samples. The ability of the isolates to produce trichothecenes was determined by GC and HPLC. Fusarium graminearum was the predominant species and of 33 isolates, 10 produced deoxinivalenol (DON) (0.1- 29 mg kg-1), 13 produced both deoxinivalenol (1.0- 708 mg kg-1) and nivalenol (0.1- 6.2mg kg -1), 12 produced 3-acetyldeoxinivalenol (0.1- 14 mg kg-1), 13 produced 15-acetyldeoxinivalenol (0.1- 1.9 mg kg-1), 10 produced Fusarenone X (0.1- 2.4 mg kg-1) and 7 produced zearalenone (0.1- 0.6 mg kg-1). These results suggest that F. graminearum strains isolated from the wheat growing regions in Argentina belong to DON chemotype. Although some strains produced both deoxinivalenol and nivalenol, nivalenol was produced in lower levels. The natural occurrence of nivalenol in wheat affected by head-blight collected in the main production area during two years (2001-2002) was also determined. From 19 samples 13 were contaminated with deoxinivalenol in a range of 0.3 to 70 mg kg-1 and 2 samples with both deoxinivalenol (7.5 and 6.7 mg kg-1) and nivalenol (0.05 and 0.1 mg kg -1), respectively. This is the first report of natural occurrence of nivalenol in wheat cultivate in Argentina.

Descripción: In the spirit of the work of Grothendieck, we introduce and study natural symmetric n-fold tensor norms. These are norms obtained from the projective norm by some natural operations. We prove that there are exactly six natural symmetric tensor norms for n≥ 3, a noteworthy difference with the 2-fold case in which there are four. We also describe the polynomial ideals associated to these natural symmetric tensor norms. Using a symmetric version of a result of Carne, we establish which natural symmetric tensor norms preserve the Banach algebra structure. © 2011 Elsevier Inc.

Descripción: To gain insights into the natural variation of root hydraulics and its molecular components, genotypic differences related to root water transport and plasma membrane intrinsic protein (PIP) aquaporin expression were investigated in 13 natural accessions of Arabidopsis (Arabidopsis thaliana). The hydraulic conductivity of excised root systems (Lpr) showed a 2-fold variation among accessions. The contribution of aquaporins to water uptake was characterized using as inhibitors mercury, propionic acid, and azide. The aquaporin-dependent and -independent paths of water transport made variable contributions to the total hydraulic conductivity in the different accessions. The distinct suberization patterns observed among accessions were not correlated with their root hydraulic properties. Real-time reverse transcription-polymerase chain reaction revealed, by contrast, a positive overall correlation between Lpr and certain highly expressed PIP transcripts. Root hydraulic responses to salt stress were characterized in a subset of five accessions (Bulhary-1, Catania-1, Columbia-0, Dijon-M, and Monte-Tosso-0 [Mr-0]). Lpr was down-regulated in all accessions except Mr-0. In Mr-0 and Catania-1, cortical cell hydraulic conductivity was unresponsive to salt, whereas it was down-regulated in the three other accessions. By contrast, the five accessions showed qualitatively similar aquaporin transcriptional profiles in response to salt. The overall work provides clues on how hydraulic regulation allows plant adaptation to salt stress. It also shows that a wide range of root hydraulic profiles, as previously reported in various species, can be observed in a single model species. This work paves the way for a quantitative genetics analysis of root hydraulics. © 2011 American Society of Plant Biologists.

Descripción: Fil:Chimento, L.P. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.

Descripción: The title compound, C 9H 14N +· CHB 11Cl 11 -, was obtained in the course of our continuing studies of the low-melting salts of closo- and nido-carborane cage anions with alkyl-pyridinium and dialkyl-imidazolium cations. The title compound is the first example of a pyridinium salt of a perchlorinated carborane anion. The structure consists of one N-butyl-pyridinium cation counterbalanced by one perchlorinated carborane cage anion per asymmetric unit. By changing the counter-ion, different packings are observed, and to try to understand this the new structure is compared with five similar compounds. © 2011 International Union of Crystallography.

Descripción: Neactaeonina argentina, a new species from the outer Argentine shelf off Buenos Aires province, is described. The species is characterized by the elongate, low-spired shell, with shouldered, nearly straight whorls, deep suture, and sculpture composed of numerous, broad, flat spiral cords. The radula is similar to that previously described for the type species, Neactaeonina cingulata Thiele, 1912, except in having a greater number of teeth. The present study provides the first information on the anatomy and histology of the genital system, and details of the radula anatomy of Neactaeonina, both unknown to date. The study of anatomical characters demonstrates that Neactaeonina has clear similarities with other Acteonidae, with a combination of features present in Acteon (such as the presence of a strongly calcified shell, with well-developed operculum; mantle cavity opening anteriorly; nervous system with only the cerebropleural ganglia fused; a single allosperm sac associated with the female system; radula without cardinal tooth; and oral cuticle with rod-like processes); and some characters present in acteonid genera other than Acteon (e.g., the number and morphology of teeth, and processes of the oral cuticle). However, Neactaeonina shows some characters thus far not reported for any other genus currently placed into the Acteonidae: salivary glands with laminar structure, male genital system with an open portion, a single allosperm sac opening distally, and a flat and triangular copulatory organ.

Descripción: A necessary and sufficient condition is established for a state to converge to equilibrium in a dynamical system described as a Kolmogorov system. Because the time reversal of a state converging to equilibrium does not necessarily share this property, this opens the possibility of spontaneous breaking of time reversal symmetry. © 1991 American Institute of Physics.

Descripción: We address Bass' question, on whether Kn(R) = Kn(R[t]) implies Kn(R) = Kn(R[t1, t2]). In a companion paper, we establish a positive answer to this question when R is of finite type over a field of infinite transcendence degree over the rationals. Here we provide an example of an isolated surface singularity over a number field for which the answer the Bass' question is "no" when n = 0. © c 2010 American Mathematical Society.

Descripción: Fil:Llambías, E.B.C. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.

Descripción: The Chancho-Co hill is the main positive feature in the caldera del Agrio domain with the only exception of the Copahue volcano. Its development is lin- ked to a series of NE-trending thrusts with a general vergence to the SE, which affects Late Pliocene successions gathered in Las Mellizas Formation. The main topographic break in this fan of reverse faults coincides with the Copahue Fault. This structure uplifted Late Pliocene sequences over younger unconsolidated fluvial and coluvial deposits. The detailed study of these sequences allowed identifying at least two periods of activity for the Copahue Fault. This fault, as well as the other neigh- bor thrusts, cuts the Copahue lavas to the south showing the precise geometry of the Chanchó-Co uplift. Finally, the inver- sion of Paleogene depocenters at depth determined from gravimetric studies is proposed to explain the deeper geometry of the neotectonic structures in the area.

Descripción: Modification of nesting sites caused by human activity can have a negative effect on the reproductive success of birds. In recent decades, a population of Red-crested Cardinal (Paroaria coronata) was established in a modified forest with ecotourism intense activity. In this paper, we model the daily nest survival rate of this population of Red-crested Cardinal and we assessed the effect of time of season, age of nest and environmental variables. Between 2007 and 2009 we monitored 69 nests found in areas with different eco-tourist activity and we used the program MARK to estimate and model the daily survival rates. Only six nests produced fledglings and the main cause of nest failure was predation (88%). Nest survival increased with the vegetation cover around the nest and decreased with the date of the breeding season. We found no significant effect in nest survival of the activities related to ecotourism. The coverage around the nest could reduce their exposure by decreasing their detectability and hindering the access of predators, while the decrease in survival over the season could be the result of changes in the community of predators. The low nest survival associated with high rates of nest predation suggest that, in this study site, predator community could be being affected by human habitat alterations. © The Neotropical Ornithological Society.

Descripción: We studied different functional attributes on two Schoenoplectus californicus (C. A. Mey) Sójak marshes that appear as very similar communities in terms of structure and dominant species, although they are settled on opposite ends along a fluvial-tidal gradient in the Lower Delta of the Paraná River. Obtained results showed a significantly higher net aboveground primary production (NAPP) in the marsh directly affected by tides (1999.41 ± 211.97 g m-2 year-1). In the upstream site, less prone to tidal flooding, S. californicus had a lower NAPP (1299.17 ± 179.48 g m-2 year-1) and the system showed a higher ability to keep the produced biomass within the marsh, with significantly higher amounts of standing dead biomass (1316.00 ± 336.01 vs. 112.40 ± 55.05 g m-2), as well as higher organic contents in soils (16.20 ± 0.12 % vs. 0.70 ± 0.08 %). Results of the present study suggest that high energy overland flows may change the marsh functioning from a stable system accumulating organic matter to an aggressively growing marsh with higher rates of mineral accumulation.

Descripción: Let J: ℝ → ℝ be a nonnegative, smooth function with ∫ℝ J(r)dr = 1, supported in [-1, 1], symmetric, J(r) = J(-r), and strictly increasing in [-1,0]. We consider the Neumann boundary value problem for a nonlocal, nonlinear operator that is similar to the porous medium, and we study the equation ut(x, t)=∫L-L(J(x-y/ u(y,t) - J(x-y/u(x, t))dy, x∈[-L, L].We prove existence and uniqueness of solutions and a comparison principle. We find the asymptotic behaviour of the solutions as t → ∞: they converge to the mean value of the initial data. Next, we consider a discrete version of the above problem. Under suitable hypotheses we prove that the discrete model has properties analogous to the continuous one. Moreover, solutions of the discrete problem converge to the continuous ones when the mesh parameter goes to zero. Finally, we perform some numerical experiments. © 2007 American Mathematical Society.

Descripción: In prior work, a series of two-point boundary value problems have been investigated for a steady state two-ion electro-diffusion model system in which the sum of the valencies ν + and ν - is zero. In that case, reduction is obtained to the canonical Painlevé II equation for the scaled electric field. Here, a physically important Neumann boundary value problem in the generic case when ν ++ν - = 0 is investigated. The problem is novel in that the model equation for the electric field involves yet to be determined boundary values of the solution. A reduction of the Neumann boundary value problem in terms of elliptic functions is obtained for privileged valency ratios. A topological index argument is used to establish the existence of a solution in the general case, under the assumption ν ++ν - ≤ 0.

Descripción: We study a Neumann boundary-value problem on the half line for a second order equation, in which the nonlinearity depends on the (unknown) Dirichlet boundary data of the solution. An existence result is obtained by an adapted version of the method of upper and lower solutions, together with a diagonal argument. ©2008 Texas State University.

Descripción: Dirichlet boundary conditions on a surface can be imposed on a scalar field, by coupling it quadratically to a δ-like potential, the strength of which tends to infinity. Neumann conditions, on the other hand, require the introduction of an even more singular term, which renders the reflection and transmission coefficients ill-defined because of UV divergences. We present a possible procedure to tame those divergences, by introducing a minimum length scale, related to the nonzero 'width' of a nonlocal term. We then use this setup to reach (either exact or imperfect) Neumann conditions, by taking the appropriate limits. After defining meaningful reflection coefficients, we calculate the Casimir energies for flat parallel mirrors, presenting also the extension of the procedure to the case of arbitrary surfaces. Finally, we discuss briefly how to generalize the worldline approach to the nonlocal case, what is potentially useful in order to compute Casimir energies in theories containing nonlocal potentials; in particular, those which we use to reproduce Neumann boundary conditions. © 2010 Elsevier B.V. All rights reserved.

Descripción: Previous studies of musical creativity suggest that this process involves multi-regional intra and interhemispheric interactions, particularly in the prefrontal cortex. However, the activity of the prefrontal cortex and that of the parieto-temporal regions, seems to depend on the domains of creativity that are evaluated and the task that is performed. In the field of music, only few studies have investigated the brain process of a creative task and none of them have investigated the effect of the level of creativity on the recruit networks. In this work we used magnetic resonance imaging to explore these issues by comparing the brain activities of subjects with higher creative abilities to those with lesser abilities, while the subjects improvised on different rhythmic fragments. We evaluated the products the subjects created during the fMRI scan using two musical parameters: fluidity and flexibility, and classified the subjects according to their punctuation. We examined the relation between brain activity and creativity level. Subjects with higher abilities generated their own creations based on modifications of the original rhythm with little adhesion to it. They showed activation in prefrontal regions of both hemispheres and the right insula. Subjects with lower abilities made only partial changes to the original musical patterns. In these subjects, activation was only observed in left unimodal areas. We demonstrated that the activations of prefrontal and paralimbic areas, such as the insula, are related to creativity level, which is related to a widespread integration of networks that are mainly associated with cognitive, motivational and emotional processes. © 2013 Villarreal et al.

Descripción: It is universally true in ecological communities, terrestrial or aquatic, temperate or tropical, that some species are very abundant, others are moderately common, and the majority are rare. Likewise, eukaryotic genomes also contain classes or "species" of genetic elements that vary greatly in abundance: DNA transposons, retrotransposons, satellite sequences, simple repeats and their less abundant functional sequences such as RNA or genes. Are the patterns of relative species abundance and diversity similar among ecological communities and genomes? Previous dynamical models of genomic diversity have focused on the selective forces shaping the abundance and diversity of transposable elements (TEs). However, ideally, models of genome dynamics should consider not only TEs, but also the diversity of all genetic classes or "species" populating eukaryotic genomes. Here, in an analysis of the diversity and abundance of genetic elements in >500 eukaryotic chromosomes, we show that the patterns are consistent with a neutral hypothesis of genome assembly in virtually all chromosomes tested. The distributions of relative abundance of genetic elements are quite precisely predicted by the dynamics of an ecological model for which the principle of functional equivalence is the main assumption. We hypothesize that at large temporal scales an overarching neutral or nearly neutral process governs the evolution of abundance and diversity of genetic elements in eukaryotic genomes. © 2013 Serra et al.

Descripción: The use of neutron inelastic scattering measurements to determine the nature of the solid-state transitions in globular compounds is proposed and exemplified. Patterns were taken of the high- and low-temperature phases of solid cyclohexane, 2-2-dimethylbutane, and 1-4-diazo-bicyclo-(2.2.2)-octane. The first two have broad inelastic scattering peaks in the low-temperature phase. In the high-temperature phase these peaks disappear and the elastic peak broadens markedly. These changes are attributed to "quasi-free- rotation" of the molecules. Inelastic peaks do not appear in 1-4-diazo-bicyclo-(2.2.2)-octane, and the elastic peak does not broaden appreciably in the high-temperature phase. Self-diffusion coefficients D 3=4.5×10-5 cm2/sec for cyclohexane and D3=8.6×10-5 cm2/sec for 2-2-dimethylbutane were determined from the patterns of the liquids at 300°K using the "small motions" approximation. These values are larger than those obtained from NMR measurements, presumably as a result of irreversible rotation of the molecules.

Descripción: The subcellular localization and physiological functions of biomolecules are closely related and thus it is crucial to precisely determine the distribution of different molecules inside the intracellular structures. This is frequently accomplished by fluorescence microscopy with well-characterized markers and posterior evaluation of the signal colocalization. Rigorous study of colocalization requires statistical analysis of the data, albeit yet no single technique has been established as a standard method. Indeed, the few methods currently available are only accurate in images with particular characteristics. Here, we introduce a new algorithm to automatically obtain the true colocalization between images that is suitable for a wide variety of biological situations. To proceed, the algorithm contemplates the individual contribution of each pixel's fluorescence intensity in a pair of images to the overall Pearsońs correlation and Manders' overlap coefficients. The accuracy and reliability of the algorithm was validated on both simulated and real images that reflected the characteristics of a range of biological samples. We used this algorithm in combination with image restoration by deconvolution and time-lapse confocal microscopy to address the localization of MEK1 in the mitochondria of different cell lines. Appraising the previously described behavior of Akt1 corroborated the reliability of the combined use of these techniques. Together, the present work provides a novel statistical approach to accurately and reliably determine the colocalization in a variety of biological images. © 2011 Villalta et al.

Descripción: A new trechonolide-type withanolide, jaborosolactol, possessing a hemiketal ring system and a 5-membered lactol, has been isolated from the aerial parts of Jaborosa lanigera. The structure was elucidated based on spectroscopic and spectrometric methods (ID and 2D NMR, MS). The feeding deterrent activity of the compound against the Mediterranean fruit fly Ceratitis capitata was examined. © 2007 Verlag der Zeitschrift für Naturforschung.

Descripción: The base chromosome number of x = 11 is the most probable in all the subtribes included in tribe Phaseoleae, although some aneuploid reduction is evident in Collaea and Galactia (Diocleinae) and chromosome duplications are seen in Amphicarpaea, Cologania and Glycine (Glycininae). The aims of this study were to improve the cytological knowledge of some species of Collaea and Galactia and to examine the anomalous counts reported for Calopogonium (Glycininae) and verify its taxonomic position. In addition, a molecular phylogeny was constructed using nuclear ribosomal DNA sequences (internal transcribed spacer region), and the chromosome number was optimized on the topology. In this work, the chromosome counts for Galactia lindenii, Galactia decumbens and Collaea cipoensis (all 2n = 20), and Calopogonium sericeum (2n = 22) are reported for the first time. The new reports for Galactia and Collaea species are in agreement with the chromosome number proposed for subtribe Diocleinae. The study rejects the concept of a cytologically anomalous Calopogonium and, based on the phylogenetic analysis, corroborates the position of this genus within subtribe Glycininae. The ancestral basic chromosome number of x = 11 proposed for Phaseoleae is in agreement with the evolutionary pathway of chromosome numbers analysed in this work. © 2008 The Linnean Society of London.

Descripción: Fil:Litvak, V.D. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.

Descripción: Four species of Diodia are transferred to Diodella, and the new combinations are: Diodella gardneri, Diodella mello-barretoi, Diodella sarmentosa and Diodella scandens.

Descripción: The monotypic Notiomys is the most poorly-known genus of Abrotrichini, a recently erected tribe of South American sigmodontine rodents. Based on a large sample, mostly recovered from owl pellets but including trapped individuals, we refine the known geographic distribution of this mouse (providing 20 new contemporary recording localities and four fossil occurrences), relate this to the principal Patagonian environmental units, add new data on the type locality of the species, and comment on its conservation status. In addition, we present a detailed external and craniodental description and provide data showing geographic variation of some skull features. Finally, we provide preliminary data on genetic variation (cytochrome b gene sequences) that demonstrate the existence of a low degree of observed differentiation (ca. 0.7%) between the populations analyzed. © 2008 by Walter de Gruyter.

Descripción: A continental sequence of red beds and interbedded basaltic layers crops out in the Sierra Chica of Cordoba Province, Argentina (31.5°S, 64.4°W). This succession was deposited in a half-graben basin during the Early Cretaceous. We have carried out a palaeomagnetic survey on outcrops of this basin (147 sites in seven localities). From an analysis of IRM acquisition curves and detailed demagnetization behaviour, three different magnetic components are identified in the volcanic rocks: components A, B and X are carried by single- or pseudo-single-domain (titano) magnetite, haematite and multidomain magnetite, respectively. Component A is interpreted as a primary component of magnetization because it passes conglomerate, contact, tilt and reversal tests. The carrier of the primary magnetization, fine-grained (titano) magnetite, is present in basalts with a high degree of deuteric oxidation. This kind of oxidation is interpreted to have occurred during cooling. Components B and X are discarded because they are interpreted as recent magnetizations. In the sedimentary rocks, haematite and magnetite are identified as the carriers of remanence. Both minerals carry the same component, which passes a reversal test. The calculated palaeomagnetic pole, based on 55 sites, is Lat. 86.0°S, Long. 75.9°E (A95=3.3, K=35). This palaeomagnetic pole supersedes four with anomalous positions reported in previous papers.

Descripción: The Sierras Australes de la Provincia de Buenos Aires or Sierra de la Ventana are situated in the south part of Buenos Aires province, Argentina, between 37°-39°S and 61°-63°W, and constitute a curved fold and thrust belt with a general northwest strike. They are formed of Precambrian to Permian rocks. The oldest and more intensely deformed rocks out in the western ranges, whereas the younger and less deformed are located in the east. Traditionally, these ranges were considered as an example of pure folding without any associated faulting. In this paper, mesoscale structural sections that prove the importance of faulting in the ranges development are described. On a regional scale, the presence of tectonic contacts between the Lolen Formation (upper Devonian) and Providencia Formation (lower Devonian), and between the latter and the Neposta Formation (lower Devonian) are suggested in Parque Tornquist, Estancia Las Vertientes and at Cerro Tres Picos. Field evidence, suggests that the Pillahunico Ranges are structurally higher than the Ventana Ranges, because of a north-east dipping underthrust.

Descripción: The Traveling Deliveryman Problem is a generalization of the Minimum Cost Hamiltonian Path Problem where the starting vertex of the path, i.e. a depot vertex, is fixed in advance and the cost associated with a Hamiltonian path equals the sum of the costs for the layers of paths (along the Hamiltonian path) going from the depot vertex to each of the remaining vertices. In this paper, we propose a new Integer Programming formulation for the problem and computationally evaluate the strength of its Linear Programming relaxation. Computational results are also presented for a cutting plane algorithm that uses a number of valid inequalities associated with the proposed formulation. Some of these inequalities are shown to be facet defining for the convex hull of feasible solutions to that formulation. These inequalities proved very effective when used to reinforce Linear Programming relaxation bounds, at the nodes of a Branch and Bound enumeration tree. © 2008 Elsevier B.V. All rights reserved.

Descripción: This paper describes Regoella brevis gen. n. et. sp. n. (Proteocephalidea: Monticelliinae), a parasite of the intestine of the barred sorubim Pseudoplatystoma fasciatum (Linnaeus) from the Paraná River basin. The new genus is placed in the Monticelliinae because of the cortical position of the genital organs. It differs from all known genera included in the Monticelliinae by the following combination of characters: 1) a quadrangular scolex with a truncated conical apex and formed by four lobes separated by grooves; 2) uniloculate suckers of inverted triangular shape possessing a small cone-shaped projection at each corner of the anterior margin; 3) strobila consisting of a low number of proglottides; 4) testes arranged in one dorsal field; 5) a cirrus-sac, which represents more than one half of the proglottis width, cirrus surrounded by conspicuous chromophilic gland cells; 6) a butterfly-shaped and strongly lobulate ovary; and 7) formation of uterus of type 2. The examination of the tegument surface with scanning electron microscopy revealed the occurrence of three types of microtriches: acicular and capilliform filitriches and gladiate spinitriches. The new species is the eighth proteocephalidean reported from P. fasciatum, six of which are commonly found in the Amazon and Paraná River basins. © Institute of Parasitology, Biology Centre ASCR.

Descripción: In the southern border of Laguna de Pozuelos Basin, the Pan de Azúcar volcanic complex crops out. It consists of several dacitic volcanic dome centers of ~ 12 Ma. Previous interpretation of seismic lines and a detailed ground magnetic survey indicated the presence of buried intrusive bodies. The determination of the existence of buried bodies has two major implications: 1) these volcanic complexes are closely associated with ore deposits (as part of the Bolivian tin ore polymetallic belt); and 2) the existence of a large ancient caldera (~12 Ma) beneath the central and southern part of the Laguna de Pozuelos Basin, covered by the infilling sediments was previously suggested. The volcanic complexes would represent the final stages of such a calderic magmatic system. In order to confirm the existence of other buried intrusives and/or a buried caldera system, detailed ground magnetic and gravity surveys were carried out. The magnetic map is dominated by positive and negative anomalies in the southern sector of the basin, associated with the dacitic domes. The residual Bouguer anomaly presents a semicircular pattern, having only positive values. We applied the curvature technique to analyse the magnetic and gravity signals and used Euler deconvolution to estimate the depth to the sources. Our results would support the hypothesis of a large caldera buried beneath the Laguna de Pozuelos Basin. The identification of such a large Middle Miocene caldera would bring new insight into the magmatic evolution of the northern Puna.

Descripción: To identify wild hosts of Trypanosoma cruzi, surveys were conducted in the subandean valleys of Jujuy Province, Argentina, between June 1986 and March 1987. Seventy two mammals from 13 different species were examined by xenodiagnosis. Fifty two of them were mostly rodents trapped at the localities of Maimará, León and Tilcara, and the remainder had been kept in captivity at the Estación Biológica Experimental, in Jujuy. Trypanosoma cruzi infection was detected only in 2 Octodontomys gliroides (2 pos./8 exam. 25%) from all 72 examined mammals. Isolates were called Octodontomys Argentina 1 and 2 (OA1 and OA2). Both infected animals were caught at the archaelogical ruin of Pucará, at Tilcara. Repeated searches for triatomines in the ruin itself and in neighbour houses rendered negative results. Groups of mice inoculated with either OA1 or OA2 isolates became infected between 7 (OA1) to 12 days (OA2) postinoculation PI. Parasitemia peaks were observed between day 12th-14th PI. Scarce amastigote nests were found in myocardium and skeletal muscle. Mortality was observed only for mice inoculated with OA1. Isoenzyme patterns of OA1 and OA2 were identical to one found in dogs and slightly different from that of human parasites in Argentina. Bones from Octodontomys sp., were recently found in a cave, dated 10200-8600 BC, in Pumamarca, near Tilcara, Jujuy. There are evidences that O. gliroides cohabited with man in ancient times and was associated to the domestic cycle of T. cruzi transmission, playing a role like that of domestic caves in Bolivia.

Descripción: Background: Human papillomavirus (HPV) is the main causative agent of cervical cancer, particularly high risk strains such us HPV-16, -18 and -31. The viral encoded E2 protein acts as a transcriptional modulator and exerts a key role in viral DNA replication. Thus, E2 constitutes an attractive target for developing antiviral agents. E2 is a homodimeric protein that interacts with the DNA target through an α-helix of each monomer. However, a peptide corresponding to the DNA recognition helix of HPV-16 E2 binds DNA with lower affinity than its full-length DNA binding domain. Therefore, in an attempt to promote the DNA binding of the isolated peptide, we have designed a conjugate compound of the E2 α-helix peptide and a derivative of the antibiotic distamycin, which involves simultaneous minor- and major-groove interactions. Methodology/Principal Findings: An E2 α-helix peptide-distamycin conjugate was designed and synthesized. It was characterized by NMR and CD spectroscopy, and its DNA binding properties were investigated by CD, DNA melting and gel shift experiments. The coupling of E2 peptide with distamycin does not affect its structural properties. The conjugate improves significantly the affinity of the peptide for specific DNA. In addition, stoichiometric amounts of specific DNA increase meaningfully the helical population of the peptide. The conjugate enhances the DNA binding constant 50-fold, maintaining its specificity. Conclusions/Significance: These results demonstrate that peptide-distamycin conjugates are a promising tool to obtain compounds that bind the E2 target DNA-sequences with remarkable affinity and suggest that a bipartite major/minor groove binding scaffold can be a useful approach for therapeutic treatment of HPV infection. © 2011 Wetzler et al.

Descripción: The planetary hypothesis of solar cycle is an old idea by which the planetary gravity acting on the Sun might have a non-negligible effect on the solar magnetic cycle. The advance of this hypothesis is based on phenomenological correlations between dynamical parameters of the Sun's movement around the barycenter of the Solar System and sunspots time series. In addition, several authors have proposed, using different methodologies that the first Grand Minima (GM) event of the new millennium is coming or has already begun. We present new fully three dimensional N-body simulations of the solar inertial motion (SIM) around the barycentre of the solar system in order to perform a phenomenological comparison between relevant SIM dynamical parameters and the occurrences of the last GM events (i.e., Maunder and Dalton). Our fundamental result is that the Sun acceleration decomposed in a co-orbital reference system shows a very particular behaviour that is common to Maunder minimum, Dalton minimum and the maximum of cycle 22 (around 1990), before the present prolonged minimum. We discuss our results in terms of a dynamical characterization of GM with relation to Sun dynamics and possible implications for a new GM event. © 2012 International Astronomical Union.

Descripción: The Saccharomyces cerevisiae UGA4 gene, which encodes the γ-aminobutyric acid (GABA) and δ-aminolaevulinic acid (ALA) permease, is well known to be regulated by the nitrogen source. Its expression levels are low in the presence of a rich nitrogen source but are higher when a poor nitrogen source is used. In addition, GABA can induce UGA4 expression when cells are grown with proline but not when they are grown with ammonium. Although vast amounts of evidence have been gathered about UGA4 regulation by nitrogen, little is known about its regulation by the carbon source. Using glucose and acetate as rich and poor carbon source respectively, this work aimed to shed light on hitherto unclear aspects of the regulation of this gene. In poor nitrogen conditions, cells grown with acetate were found to have higher UGA4 basal expression levels than those grown with glucose, and did not show UGA4 induction in response to GABA. Analysis of the expression and subcellular localization of the transcription factors that regulate UGA4 as well as partial deletions and site-directed mutations of the UGA4 promoter region suggested that there are two parallel pathways that act in regulating this gene by the carbon source. Furthermore, the results demonstrate the existence of a new factor operating in UGA4 regulation. © 2007 SGM.

Descripción: We describe useful vectors to select double-crossover events directly in site-directed marker exchange mutagenesis in gram-negative bacteria. These vectors contain the gusA marker gene, providing colorimetric screens to identify bacteria harboring those sequences. The applicability of these vectors was shown by mapping the 3' end of the Xanthomonas campestris gum operon, involved in biosynthesis of xanthan.

Descripción: Context. Magnetic clouds are transient magnetic structures expulsed from the Sun that travel toward the external heliosphere carrying a significant amount of magnetic flux and helicity. Aims. To improve our understanding of magnetic clouds in relation to their solar source regions, we need a reliable method to compute magnetic flux and helicity in both regions. Here we evaluate the sensitivity of the results using different models, methods and magnetic cloud boundaries applied to the same magnetic cloud data. Methods. The magnetic cloud was observed by the spacecraft Wind on October 18-20, 1995. We analyze this cloud considering four different theoretical configurations (two force free and two non-force free) that have been previously proposed to model cloud fields. These four models are applied using two methods to determine the orientation of the cloud axis: minimum variance and simultaneous fitting. Finally, we present a new method to obtain the axial and azimuthal magnetic fluxes and helicity directly from the observed magnetic field when rotated to the cloud frame. Results, The results from the fitted models have biases that we analyze, The new method determines the centre and the rear boundary of the flux rope when the front boundary is known. It also gives two independent measurements in the front and back parts for the fluxes and helicity; they are free of model and boundary biases. We deduce that the leading flux of the magnetic cloud had reconnected with the overtaken solar wind magnetic field and estimate the fluxes and helicity present in the full cloud before this reconnection. © ESO 2006.

Descripción: Extracellular signal-regulated protein kinase 1 and 2 (ERK1/2) are members of the MAPK family and participate in the transduction of stimuli in cellular responses. Their long-term actions are accomplished by promoting the expression of specific genes whereas faster responses are achieved by direct phosphorylation of downstream effectors located throughout the cell. In this study we determined that hERK1 translocates to the mitochondria of HeLa cells upon a proliferative stimulus. In the mitochondrial environment, hERK1 physically associates with (i) at least 5 mitochondrial proteins with functions related to transport (i.e. VDAC1), signalling, and metabolism; (ii) histones H2A and H4; and (iii) other cytosolic proteins. This work indicates for the first time the presence of diverse ERK-complexes in mitochondria and thus provides a new perspective for assessing the functions of ERK1 in the regulation of cellular signalling and trafficking in HeLa cells. © 2009 Galli et al.

Descripción: A new polymeric phase of zinc(II) oxydiacetate, catena-poly[[[diaquazinc(II)]-μ-oxydiacetato] hydrate], {[Zn(C4H4-O5)(H2O)2] ·H2O}n, isomorphous with the Co homologue [Hatfield, Helms, Rohrs, Singh, Wasson & Weller (1987). Proc. Indian Acad. Sci. Chem. Sci. 98, 23-31], is reported. It presents a chain-like structure, generated by ZnO6 cores which are bridged by carboxylate groups in an anti-anti conformation along the unique crystallographic b axis. The chains are held together through hydrogen-bonding interactions with the three water molecules.

Descripción: New absolute ages derived from whole rock K/Ar dating of two vitric tuffs collected from the upper-middle part of the Toro Negro Formation in the outcrops of the Sierra de Los Colorados, Sierras Pampeanas Noroccidentales (La Rioja Province) are presented herein. The obtained values of 8,6 ± 0,3 Ma and 6,8 ± 0,2 Ma respectively, indicate an Upper Miocene age and challenge the previous Pliocene age proposed for this unit. The results pressented here have a high degree of confidence because they do not show evidences of reworking, mixing with terrigenous clastics nor diagenetic alteration. The tuff levels were mapped and georeferenced using GPS coordinates and their close location in the stratigraphic column provides an additional control for the obtained ages. © 2005 Asociación Geológica Argentina.

Descripción: From the aerial parts of Salpichroa origanifolia a new withanolide in which the C-13 angular methyl has migrated to C-17, was isolated and characterized by spectroscopic methods.

Descripción: A recombinant E. coli strain (K24K) was constructed and evaluated For poly(3-hydroxybutyrate) (PHB) production from whey and corn steep liquor as main carbon and nitrogen sources. This strain bears the pha biosynthetic genes from Azotobacter sp. strain FA8 expressed from a T5 promoter under the control of the lactose operator. K24K does not produce the lactose repressor, ensuring constitutive expression of genes involved in lactose transport and utilization. PHB was efficiently produced by the recombinant strain grown aerobically in fed-batch cultures in a laboratory scale bioreactor on a semisynthetic medium supplemented with the agroindustrial by-products. After 24 h, cells accumulated PHB to 72.9% of their cell dry weight, reaching a volumetric productivity of 2.13 g PHB per liter per hour. Physical analysis of PHB recovered from the recombinants showed that its molecular weight was similar to that of PHB produced by Azotobacter sp. strain FA8 and higher than that of the polymer from Cupriavidus necator and that its glass transition temperature was approximately 20°C higher than those of PHBs from the natural producer strains. Copyright © 2006, American Society for Microbiology. All Rights Reserved.

Descripción: Three species of Eryngium that constitute new records or problematic taxa for the Floras of Argentina and Uruguay are presented. E. balansae, known from Paraguay and Brazil, is recorded from Argentina for the first time. E. regnellii, originally described from Brazil, is recorded here from Argentina and Uruguay. This species, abundant in highlands of both countries, was in previously confused with E. stenophyllum in floristic and ecological studies. This last name designates an infrequent and poorly known species, and thus it is considered appropriate to here recharacterize it. For each of these three taxa a description, illustrations and a distribution map is provided, as well as a key to the Argentine species of Eryngium sect. Parmiculata ser. Latifolia, the group to which the three entities belong.

Descripción: Twelve species of Xylaria are cited as new records from Argentina: Xylaria adscendens, X. allantoidea, X. coccophora, X. cubensis, X. fissilis, X. gracillima, X. luxurians, X. melanura, X. multiplex, X. myosurus, X. kretschmarioidea and X. pseudoapiculata. The last two species are reported for the second time globally. We described for the first time the anamorphic or sterile stromata obtained in culture of X. kretschmarioidea, X. luxurians and X melanura, and cultures in oatmeal-agar of X. pseudoapiculata. X. torulosa is synonymized under X. coccophora, and new substrates and hosts are reported for most species.

Descripción: Resistive random access memory based on the resistive switching phenomenon is emerging as a strong candidate for next generation non-volatile memory. So far, the resistive switching effect has been observed in many transition metal oxides, including strongly correlated ones, such as, cuprate superconductors, colossal magnetoresistant manganites and Mott insulators. However, up to now, no clear evidence of the possible relevance of strong correlation effects in the mechanism of resistive switching has been reported. Here, we study Pr 0.7 Ca0.3 MnO3, which shows bipolar resistive switching. Performing micro-spectroscopic studies on its bare surface we are able to track the systematic electronic structure changes in both, the low and high resistance state. We find that a large change in the electronic conductance is due to field-induced oxygen vacancies, which drives a Mott metal-insulator transition at the surface. Our study demonstrates that strong correlation effects may be incorporated to the realm of the emerging oxide electronics.

Descripción: Three species of Cercophora were found during a survey of the biodiversity of microfungi in northwest Argentina. Cercophora argentina possesses a unique combination of morphological characters and is described as a new species, while C. costaricensis and C. solaris are reported as new records for Argentina. Other species of Cercophora known from this region include C. natalita and C. coprogena, which is fully illustrated for the first time and determined herein to be a synonym of C. californica. All other species are described and illustrated. © 2011 by The Mycological Society of America.

Descripción: A new ammonoid species of the Andean endemic genus Andiceras Krantz is here described from upper Tithonian-lower Berriasian levels of the Vaca Muerta and Chachao Formations of the Mendoza Group, in north-western Mendoza Province, Argentina. Andiceras planulatus sp. nov. lies between the last beds with representatives of the Substeueroceras koeneni Assemblage Zone of late Tithonian age and the first bed yielding elements of the Argentiniceras noduliferum Assemblage Zone of early Berriasian age, according to the traditional Andean ammonoid zonation scheme. The particular stratigraphic position of Andiceras planulatus, together with its easily recognizable morphology makes this species a good potential biostratigraphic marker for the Jurassic-Cretaceous boundary in the Andean region.

Descripción: Marasmius tyrius is proposed as a new species. It is characterized by collariate lamellae, insititious stipe, violet pileus, pileipellis with Siccus-type broom cells, and clavate to fusoid spores. Detailed description and illustrations of macro-and microscopic characters are provided. © 2011. Mycotaxon, Ltd.

Descripción: Fil:Güller, M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.

Descripción: Neoechinorhynchus (Hebesoma) colastinense sp. n. is described from the intestine of Pachyurus bonariensis a freshwater fish from Parana River basin. The new species is characterized by having a cylindrical trunk, elongated but swollen anteriorly; a spherical proboscis with a prominent apical organ; the anterior circle of hooks very large, alternating in 2 levels, separated from more posterior circles of hooks, but sometimes surpassing the hooks of the middle and posterior circles; a relatively long neck; the male reproductive system occupying 78-81% (79%) of the trunk length; the female reproductive system occupying 27-39% (32%) of the trunk length; and eggs elongated with polar prolongation of the fertilization membrane. Members of the species can be distinguished easily from the other species of South American Neoechinorhynchus Stiles & Hassall, 1905 because they are the only ones with characteristics of the subgenus Hebesoma. Additionally, two other species are recorded for the first time in Argentina: Neoechinorhynchus {Neoechinorhynchus) macro-nucleatus Machado Filho, 1954 from Lycengraulis grossidens and N. (N) pimelodi Brasil-Sato & Pavanelli, 1998 from several species of Pimelodus. The presence of an apical organ at the proboscis tip is recorded in the new species and N. (N.) macronucleatus. Studies using scanning electron microscopy revealed the presence of non-rimmed pores in the tegument throughout the trunk, neck and proboscis of all three species. A key to the South American species of Neoechinorhynchus is provided.

Descripción: From whole Jaborosa odonelliana plants four new withanolides containing a spiranic lactone in the side chain, were isolated and their structures elucidated by spectroscopic methods.

Descripción: We present a new technique suitable for a detailed comparison between solar dynamo models and observations. The method is based on the technique of dynamo spectroscopy proposed by Hoyng & Schutgens (1995) and bi-orthogonal decomposition of solar data. This decomposition provides a representation of the mean and fluctuating components of the flows, yielding relevant information for the comparison. To illustrate the method, we use a simple kinematic dynamo model of the solar cycle. Irregularities are introduced in the evolution of the magnetic fields modeling the turbulent behavior of the solar convective region with a random perturbation on the external source for the poloidal field. After fine tuning the parameters of the model we obtain solar like solutions displaying a magnetic cycle of 22 years, with fluctuations in its period and amplitude. In addition, the model generates Maunder-like events with a time span of 60-100 years.

Descripción: The Hooded Grebe Podiceps gallardoi has been uplisted to globally Endangered' recently mainly because of the rapid population decline suffered within the last 20 years due to factors such as nest depredation by Kelp Gull Larus dominicanus as well as destruction of colonies by wind and lake desiccation. During a census of Hooded Grebes during the 2010/2011 breeding season we found a new predator that has not previously been mentioned, the American mink Neovison vison. One individual mink killed 33 Hooded Grebes and consequently destroyed one of the five colonies found in that breeding season. Due to the characteristics of the waterbird assemblage in the area, the impact of mink could be catastrophic. © 2011 BirdLife International.

Descripción: The phytochemical study of two species of Jaborosa caulescens (var. caulescens and var. bipinnatifida) yielded the four new withanolides 1-4. The structures of the new compounds were determined using a combination of spectroscopic techniques (including 1D and 2D NMR) and Molecular Modeling.

Descripción: We classify Nichols algebras of irreducible Yetter-Drinfeld modules over nonabelian groups satisfying an inequality for the dimension of the homogeneous subspace of degree two. All such Nichols algebras are finite-dimensional, and all known finite-dimensional Nichols algebras of nonabelian group type appear in the result of our classification. We find a new finite-dimensional Nichols algebra over fields of characteristic two. © 2011.

Descripción: We construct an exact regular vortex solution to the self-dual equations of the Abelian Higgs model in noncommutative space for arbitrary values of θ. To this end, we propose an ansatz which is the analogous, in Fock space, to the one leading to exact solutions for the Nielsen-Olesen vortex in commutative space. We compute the flux and energy of the solution and discuss its relevant properties. © 2001 Published by Elsevier Science B.V.

Descripción: Testicular macrophages as well as endothelial cells, which are intimately associated with Leydig cells, constitute a potential source of paracrine nitric oxide (NO) in the testis. In the present study, we investigated the effect of NO donors on MA-10 murine Leydig tumor cell line and rat Leydig cell steroidogenesis. We show that NO donors inhibit human CG- induced steroidogenesis in both type of cells. We also studied NO mechanism of action. Contrary to what is observed in many other systems, NO inhibitory effect on Leydig cell steroidogenesis is not mediated by cyclic GMP (cGMP) because NO fails to increase cGMP production, and cGMP analogs do not reproduce NO effect. NO does not modify the production of cAMP, the main second messenger that mediates gonadotropin action. When we studied NO effect over the steroidogenic pathway in MA-10 cells, we found that NO was inhibiting the conversion of cholesterol to pregnenolone. Taken together these results show an inhibitory effect of NO donors on Leydig cell steroidogenesis, and suggest that NO can be directly inhibiting cholesterol side-chain cleavage enzyme (cytochrome P450(scc)) as it does with other heme proteins, including different cytochromes P459.

Descripción: Nitrogen 14 quadrupole coupling constants for H2CN+ and HCN are predicted via ab initio self-consistent-field and configuration interaction theory. Effects of electron correlation, basis set completeness, and geometrical structure on the predicted electric field gradients are analyzed. The quadrupole coupling constant obtained for H2CN+ is one order of magnitude less than in HCN, providing an explanation for the experimental fact that the fine structure of the microwave spectrum of H 2CN+ has not been resolved. This research also allows a reliable prediction of the nuclear quadrupole moment of 14N, namely Q(14N)=2.00×10-26 cm2. © 1986 American Institute of Physics.

Descripción: Although the existence of O-linked oligosaccharide residues in glycoproteins of Plasmodium falciparum has been shown, the existence of N- linked glycoproteins is still a matter of controversy and skepticism. This report demonstrates the unequivocal presence of N-linked glycoproteins in P. falciparum, principally in the ring and young trophozoite stages of the intraerythrocytic cycle. These glycoproteins lose their capacity to bind to concanavalin A-Sepharose after treatment of cultures with tunicamycin under conditions that do not affect protein synthesis. When the glycoproteins were treated with N-Glycanase®, oligosaccharides were released. It was possible to identify an N-linked glycoprotein of >200 kDa in the ring stage and also N-linked glycoproteins in the range of 200-30 kDa in the trophozoite stage. Treatment of trophozoites with 12 μM tunicamycin inhibited differentiation to the schizont stage. To our knowledge, this is the first report in the literature unequivocally showing N-linked glycoproteins in trophozoites of P. falciparum as well as their importance for the differentiation of the intraerythrocytic stages of this parasite.

Descripción: We analyze the order α2 s corrections to the single inclusive jet and hadron cross sections in lepton-nucleon deep inelastic scattering. The full calculations are done analytically, obtaining finite NLO partonic level cross sections for these processes. We show that in both cases the dominant partonic mechanism starts at order α2 s, being effectively a lowest order estimate, with the consequent large factorization scale uncertainty, and the likelihood of non-negligible corrections at the subsequent order in perturbation theory.

Descripción: Pineal hormone melatonin (N-acetyl-5-methoxytryptamine) is thought to modulate the calcium/calmodulin signaling pathway either by changing intracellular Ca2+ concentration via activation of its G-protein-coupled membrane receptors, or through a direct interaction with calmodulin (CaM). The present work studies the direct interaction of melatonin with intact calcium-saturated CaM both experimentally, by fluorescence and nuclear magnetic resonance spectroscopies, and theoretically, by molecular dynamics simulations. The analysis of the experimental data shows that the interaction is calcium-dependent. The affinity, as obtained from monitoring 15N and 1H chemical shift changes for a melatonin titration, is weak (in the millimolar range) and comparable for the N- and C-terminal domains. Partial replacement of diamagnetic Ca2+ by paramagnetic Tb3+ allowed the measurement of interdomain NMR pseudocontact shifts and residual dipolar couplings, indicating that each domain movement in the complex is not correlated with the other one. Molecular dynamics simulations allow us to follow the dynamics of melatonin in the binding pocket of CaM. Overall, this study provides an example of how a combination of experimental and theoretical approaches can shed light on a weakly interacting system of biological and pharmacological significance.

Descripción: The aggregation of α-synuclein is characteristic of Parkinson's disease (PD) and other neurodegenerative synucleinopathies. The 140-aa protein is natively unstructured; thus, ligands binding to the monomeric form are of therapeutic interest. Biogenic polyamines promote the aggregation of α-synuclein and may constitute endogenous agents modulating the pathogenesis of PD. We characterized the complexes of natural and synthetic polyamines with α-synuclein by NMR and assigned the binding site to C-terminal residues 109-140. Dissociation constants were derived from chemical shift perturbations. Greater polyamine charge (+ 2 → + 5) correlated with increased affinity and enhancement of fibrillation, for which we propose a simple kinetic mechanism involving a dimeric nucleation center. According to the analysis, polyamines increase the extent of nucleation by ∼104 and the rate of monomer addition ∼40-fold. Significant secondary structure is not induced in monomeric α-synuclein by polyamines at 15°C. Instead, NMR reveals changes in a region (aa 22-93) far removed from the polyamine binding site and presumed to adopt the β-sheet conformation characteristic of fibrillar α-synuclein. We conclude that the C-terminal domain acts as a regulator of α-synuclein aggregation.

Descripción: The title compound, N-[2-(5-methoxy-1-nitroso-1H-indol-3-yl)ethyl]acetamide, C13H15N3O3, an N-nitroso derivative of melatonin, crystallizes in the monoclinic C2/c space group. The molecules are arranged in such a way that the aromatic rings are in a planar conformation, with the alkylamide side chains in a different plane, at a dihedral angle of 108.60 (6)°. The alkylamide chains are interconnected by hydrogen bonds, constituting an infinite array.

Descripción: We consider the bosonic sector of an N = 2 supersymmetric Chern-Simons-Higgs theory in 2 + 1 dimensions. The gauge group is U (1) × SU (N) and has Nf flavors of fundamental matter fields. The model supports non-Abelian (axially symmetric) vortices when Nf ≥ N, which have internal (orientational) moduli. When Nf > N, the solutions acquire additional collective coordinates parameterizing their transverse size. We solve the BPS equations numerically and obtain local (Nf = N) and semi-local (Nf > N) string solutions. © 2007 Elsevier B.V. All rights reserved.

Descripción: We study periodic arrays of non-Abelian vortices in an SU(N) × U(1) gauge theory with Nf flavors of fundamental matter multiplets. We carefully discuss the corresponding twisted boundary conditions on the torus and propose an ansatz to solve the first order Bogomolnyi equations which we find by looking to a bound of the energy. We solve the equations numerically and construct explicit vortex solutions. © SISSA 2007.

Descripción: We analyze a universe filled with interacting dark matter, a scalar field accommodated as dark radiation along with dark energy plus a decoupled radiation term within the framework of the spatially flat Friedmann-Robertson-Walker (FRW) spacetime. We work in a three-dimensional internal space spanned by the interaction vector and use a transversal interaction Qt for solving the source equation in order to find all the interacting component energy densities. We asymptotically reconstruct the scalar field and potential from an early radiation era to the late dominate dark energy one, passing through an intermediate epoch dominated by dark matter. We apply the χ2 method to the updated observational Hubble data for constraining the cosmic parameters, contrast with the Union 2 sample of supernovae, and analyze the amount of dark energy in the radiation era. It turns out that our model fulfills the severe bound of Ωφ{symbol}(z≃1100)<0.018 at 2σ level, is consistent with the recent analysis that includes cosmic microwave background anisotropy measurements from the Atacama Cosmology Telescope and the South Pole Telescope along with the future constraints achievable by Planck and CMBPol experiments, and satisfies the stringent bound Ωφ{symbol}(z≃1010)<0.04 at 2σ level in the big-bang nucleosynthesis epoch. © 2013 Springer-Verlag Berlin Heidelberg and Società Italiana di Fisica.

Descripción: We introduce the notion of non commutative truncated polynomial extension of an algebra . A. We study two families of these extensions. For the first one we obtain a complete classification and for the second one, which we call upper triangular, we find that the obstructions to inductively construct them, lie in the Hochschild homology of . A, with coefficients in a suitable . A-bimodule. © 2012 Elsevier B.V.

Descripción: We review a recent theoretical development based on non-equilibrium Green's function formalism to study heat transport in nanomechanical devices modeled by phononic systems of coupled quantum oscillators driven by ac forces and connected to phononic reservoirs. We present the relevant equations to calculate the heat currents flowing along different regions of the setup, as well as the power developed by the time-dependent forces. We also present different strategies to evaluate the Green's functions exactly or approximately within the weak driving regime. We finally discuss the different mechanisms in which the ac driving forces deliver the energy. We show that, besides generating heat, the forces may operate exchanging energy as a quantum engine.

Descripción: In this work we analyze the existence and regularity of the solution of a nonhomogeneous Neumann problem for the Poisson equation in a plane domain Ω with an external cusp. In order to prove that there exists a unique solution in H1 (Ω) using the Lax-Milgram theorem we need to apply a trace theorem. Since Ω is not a Lipschitz domain, the standard trace theorem for H1 (Ω) does not apply, in fact the restriction of H1 (Ω) functions is not necessarily in L2 (∂Ω). So, we introduce a trace theorem by using weighted Sobolev norms in Ω. Under appropriate assumptions we prove that the solution of our problem is in H2 (Ω) and we obtain an a priori estimate for the second derivatives of the solution. © 2005 Elsevier Inc. All rights reserved.

Descripción: Fil:Trevisan, M.A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.

Descripción: This work is devoted to the study of the elliptic equation Δu = f(x, u) in a bounded domain Ω ⊂ ℝ n with a nonlinear boundary condition. We obtain various existence results applying coincidence degree theory and the method of upper and lower solutions. © 2005 Texas State University - San Marcos.

Descripción: Fil:Gómez, D.O. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.

Descripción: The fourth-rank hypermagnetizability tensor of the benzene molecule has been evaluated at the coupled Hartree-Fock level of accuracy within the conventional common-origin approach, adopting gaugeless basis sets of increasing size and flexibility. The degree of convergence of theoretical tensor components has been estimated allowing for two different coordinate systems. It is shown that a strong magnetic field perpendicular to the plane of the molecule causes a distortion of the electron charge density, which tends to concentrate in the region of the C-C bonds. This charge contraction has a dynamical origin, and can be interpreted as a feedback effect in terms of the classical Lorentz force acting on the electron current density.

Descripción: We study a nonlinear problem of pendulum-type for a p-Laplacian with nonlinear periodic-type boundary conditions. Using an extension of Mawhin's continuation theorem for nonlinear operators, we prove the existence of a solution under a Landesman-Lazer type condition. Moreover, using the method of upper and lower solutions, we generalize a celebrated result by Castro for the classical pendulum equation. Copyright © 2006 Hindawi Publishing Corporation. All rights reserved.

Descripción: In this paper we study a nonlocal equation that takes into account convective and diffusive effects, ut = J * u - u + G * (f (u)) - f (u) in Rd, with J radially symmetric and G not necessarily symmetric. First, we prove existence, uniqueness and continuous dependence with respect to the initial condition of solutions. This problem is the nonlocal analogous to the usual local convection-diffusion equation ut = Δ u + b ṡ ∇ (f (u)). In fact, we prove that solutions of the nonlocal equation converge to the solution of the usual convection-diffusion equation when we rescale the convolution kernels J and G appropriately. Finally we study the asymptotic behaviour of solutions as t → ∞ when f (u) = | u |q - 1 u with q > 1. We find the decay rate and the first-order term in the asymptotic regime. © 2007 Elsevier Inc. All rights reserved.

Descripción: We deal with boundary value problems (prescribing Dirichlet or Neumann boundary conditions) for a nonlocal nonlinear diffusion operator which is analogous to the porous medium equation. First, we prove existence, uniqueness and the validity of a comparison principle for these problems. Next, we impose boundary data that blow up in finite time and study the behavior of the solutions. © 2007.

Descripción: In this paper we study the nonlocal p-Laplacian type diffusion equation,ut (t, x) = under(∫, Ω) J (x - y) | u (t, y) - u (t, x) |p - 2 (u (t, y) - u (t, x)) d y . If p > 1, this is the nonlocal analogous problem to the well-known local p-Laplacian evolution equation ut = div (| ∇ u |p - 2 ∇ u) with homogeneous Neumann boundary conditions. We prove existence and uniqueness of a strong solution, and if the kernel J is rescaled in an appropriate way, we show that the solutions to the corresponding nonlocal problems converge strongly in L∞ (0, T ; Lp (Ω)) to the solution of the p-Laplacian with homogeneous Neumann boundary conditions. The extreme case p = 1, that is, the nonlocal analogous to the total variation flow, is also analyzed. Finally, we study the asymptotic behavior of the solutions as t goes to infinity, showing the convergence to the mean value of the initial condition. © 2008 Elsevier Masson SAS. All rights reserved.

Descripción: Dichroplus elongatus is a grasshopper, which exhibits parallel polymorphisms for B chromosomes and supernumerary segments in chromosomes S10 (SS10), S9 (SS9) and M6 (SS6) in natural populations of Argentina. The patterns of simultaneous variation of different forms of supernumerary heterochromatin from 7 populations of two biogeographic provinces located at Northwest and East regions of this country were analysed. Spatial chromosome differentiation for all heterochromatic variants was observed. Different degree of differentiation among populations for supernumerary segments, evaluated through F(ST), was observed. This suggests that genetic drift and migration may not be the only factors involved in the maintenance of the detected chromosome patterns. The differentiation for SS9 and SS10 may be explained mainly by heterogeneity within the Northwest Region. On the contrary, the differences for SS6 and B chromosomes explained through isolation by distance. However, the absence or the low frequency of both chromosome mutations in some populations may not be explained by historical factors. A principal component analysis showed that the patterns of chromosome variation do not agree with the geographical distribution of the populations. The relationship between frequencies of each supernumerary segment and B chromosome depends on the segment. An analysis of partial correlation showed that the frequencies of B chromosomes were positively correlated with the frequency of SS6 and negatively with the frequency of the SS10. In agreement with this, a multiple regression analysis of B chromosome frequency on supernumerary segment frequencies depends on the incidence of SS6 and SS10. The covariation of the heterochromatic forms may act as another factor that establish limits to stochastic factors, may also affect the probable negative selection on B, and could be involved in the non random pattern detected in D. elongatus.

Descripción: We analyze a model of nonrelativistic matter in (2+1)-dimensional noncommutative space. The matter fields interact with gauge fields whose dynamics is dictated by a Chern-Simons term. We show that it is possible to choose the coupling constants in such a way that the model has and extended supersymmetry and Bogomolnyi equations can be found. © 2005 Elsevier B.V. All rights reserved.

Descripción: Free-volume integrals for hole theories of liquids were calculated for some special cases by Monte Carlo numerical integration. The dependence of the free volume on the number of nearest neighbors is thus obtained. Only molecules interacting with a Lennard-Jones potential and a temperature near the critical one have been considered. The results differ considerably from those of earlier theories, where spherical symmetry was assumed. However, the introduction of vacant cells (holes) does not improve the thermodynamic functions obtained with the cell theory of Lennard-Jones and Devonshire.

Descripción: Some conceptual issues concerning f(T) theories - a family of modified gravity theories based on absolute parallelism - are analyzed. Due to the lack of local Lorentz invariance, the autoparallel frames satisfying the field equations are evasive to an a priori physical understanding. We exemplify this point by working out the vierbein (tetrad) fields for closed and open Friedmann-Robertson-Walker cosmologies. © 2011 Elsevier B.V.

Descripción: In this article we construct affine systems that provide a simultaneous atomic decomposition for a wide class of functional spaces including the Lebesgue spaces Lp(Rd), 1 < p < + ∞. The novelty and difficulty of this construction is that we allow for non-lattice translations.We prove that for an arbitrary expansive matrix A and any set Λ-satisfying a certain spreadness condition but otherwise irregular-there exists a smooth window whose translations along the elements of Λ and dilations by powers of A provide an atomic decomposition for the whole range of the anisotropic Triebel-Lizorkin spaces. The generating window can be either chosen to be bandlimited or to have compact support.To derive these results we start with a known general "painless" construction that has recently appeared in the literature. We show that this construction extends to Besov and Triebel-Lizorkin spaces by providing adequate dual systems. © 2012 Elsevier Ltd.

Descripción: We present a new algorithm to compute the integral closure of a reduced Noetherian ring in its total ring of fractions. A modification, applicable in positive characteristic, where actually all computations are over the original ring, is also described. The new algorithm of this paper has been implemented in Singular, for localizations of affine rings with respect to arbitrary monomial orderings. Benchmark tests show that it is in general much faster than any other implementation of normalization algorithms known to us. © 2010 Elsevier Ltd.

Descripción: We give an elementary and direct proof of the following theorem: A real number is normal to a given integer base if, and only if, its expansion in that base is incompressible by lossless finite-state compressors (these are finite automata augmented with an output transition function such that the automata input-output behaviour is injective; they are also known as injective finite-state transducers). As a corollary we obtain V.N. Agafonov's theorem on the preservation of normality on subsequences selected by finite automata.© 2012 Elsevier B.V. All rights reserved.

Descripción: A novel appropriate definition for the density matrix for an interacting Coulombic driven atomic or molecular system with non-integer number of particles is given. Our approach leads to a direct derivation of the proposal reported by Perdew [Phys. Rev. Lett. 49, 1691 (1982)]10.1103/PhysRevLett.49.1691 and points out its suitability and perspective advances. © 2012 American Institute of Physics.

Descripción: Fil:Rossi, J.C. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.

Descripción: We continue the study of hidden Z2 symmetries of the four-point sl (2) k Knizhnik-Zamolodchikov equation initiated by Giribet [Phys. Lett. B 628, 148 (2005)]. Here, we focus our attention on the four-point correlation function in those cases where one spectral flowed state of the sector ω=1 is involved. We give a formula that shows how this observable can be expressed in terms of the four-point function of non spectral flowed states. This means that the formula holding for the winding violating four-string scattering processes in AdS3 has a simple expression in terms of the one for the conservative case, generalizing what is known for the case of three-point functions, where the violating and the nonviolating structure constants turn out to be connected one to each other in a similar way. What makes this connection particularly simple is the fact that, unlike what one would naively expect, it is not necessary to explicitly solve the five-point function containing a single spectral flow operator to this end. Instead, nondiagonal functional relations between different solutions of the Knizhnik-Zamolodchikov equation turn out to be the key point for this short path to exist. Considering such functional relation is necessary but it is not sufficient; besides, the formula also follows from the relation existing between correlators in both Wess-Zumino-Novikov-Witten (WZNW) and Liouville conformal theories. © 2007 American Institute of Physics.

Descripción: A strain isolated from Argentinean regional fermented sausages was found to produce and secrete a compound that inhibited growth of Lactobacillus strains used as indicators. It was characterized as Paenibacillus polymyxa (P13). The antimicrobial activity, named polyxin, was obtained from culture supernatant fluid of late stationary phase and was inhibitory to actively growing cells. It was effective against a wide range of Gram-positive and Gram-negative bacterial species tested including food-borne pathogens. Bacteriocin-like properties such as proteinaceous nature (sensitive to proteases), insensitivity to organic solvents and chelators, stability to heat (up to 10 min at 90°C), and acidic pH but instability in alkaline conditions, were determined. A molecular mass of 10 kDa was estimated by molecular gel filtration.

Descripción: Enzyme preparations from Xanthomonas campestris incubated in the presence of UDP-[14C]GlcA and Mg2+ produced a lipophilic galacturonide with unusual properties. It was easily degraded by both mild acid treatment (0.01 M-HCl, 100°C, 10 min) and mild alkali treatment (0.06 M-NaOH, room temperature, 5 min) releasing free [14C]galacturonic acid. The galacturonide appeared to be a single compound with one negative charge, as judged by TLC, paper electrophoresis and chromotography, LH-20 gel filtration and DEAE-cellulose column chromatography. Competition experiments indicated that the true glycosyl donor was UDP-GalA, in agreement with the detection of UDP-GlcA-4-epimerase activity in the crude enzyme preparation. The transglycosidase activity was located mainly in the membrane fraction. UDP inhibited the reaction and even produced some loss of label, suggesting an easily reversible reaction. UMP had almost no effect.

Descripción: Treatment of the chemically transformed fibroblasts BP-A31 and other cell lines with low concentrations of cycloheximide (CHM) for 72 h followed by the removal of the protein synthesis inhibitor leads to the proliferation of α-difluoromethylornithine (DFMO)-resistant phenotypes. These drug-resistant cells contain almost no ornithine decarboxylase (ODC) activity and concomitantly very low levels of putrescine and spermidine. Southern blot analysis and measurements of ODC activity and intracellular polyamine levels showed that the described mechanism of inducing resistance to DFMO triggered by CHM does not involve ODC gene amplification, altered transport of the drug or reduced affinity of the enzyme for DFMO. © 1986.

Descripción: Yerba maté extracts have in vitro antioxidant capacity attributed to the presence of polyphenolic compounds, mainly chlorogenic acids and dicaffeoylquinic acid derivatives. DPPH is one of the most used assays to measure the antioxidant capacity of pure compounds and plant extracts. It is difficult to compare the results between studies because this assay is applied in too many different conditions by the different research groups. Thus, in order to assess the antioxidant capacity of yerba maté extracts, the following procedure is proposed: 100 μL of an aqueous dilution of the extracts is mixed in duplicate with 3.0 mL of a DPPH 'work solution in absolute methanol (100 μM.L-1), with an incubation time of 120 minutes in darkness at 37 ± 1 °C, and then absorbance is read at 517 nm against absolute methanol. The results should be expressed as ascorbic acid equivalents or Trolox equivalents in mass percentage (g% dm, dry matter) in order to facilitate comparisons. The AOC of the ethanolic extracts ranged between 12.8 and 23.1 g TE % dm and from 9.1 to 16.4 g AAE % dm. The AOC determined by the DPPH assay proposed in the present study can be related to the total polyphenolic content determined by the Folin-Ciocalteu assay.

Descripción: Splitting and apparent splicing of ribosomal RNA, both previously unknown in vertebrates, were found in rodents of the genus Ctenomys. Instead of being formed by a single molecule of 4.4 kb, 28S rRNA is split in two molecules of 2.6 and 1.8 kb. A hidden break, mapping within a 106 bp 'intron' located in the D6 divergent region, is expressed in mature ribosomes of liver, lung, heart and spleen, as well as in primary fibroblast cultures. Testis-specific processing eliminates the intron and concomitantly the break site, producing non-split 28S rRNA molecules exclusively in this organ. The intron is flanked by two 9 bp direct repeats, revealing the acquisition by insertion of a novel rRNA processing strategy in the evolution of higher organisms.

Descripción: Human immunodeficiency virus type 1 (HIV-1) Gag selects for and mediates genomic RNA (vRNA) encapsidation into progeny virus particles. The host protein, Staufen1 interacts directly with Gag and is found in ribonucleoprotein (RNP) complexes containing vRNA, which provides evidence that Staufen1 plays a role in vRNA selection and encapsidation. In this work, we show that Staufen1, vRNA and Gag are found in the same RNP complex. These cellular and viral factors also colocalize in cells and constitute novel Staufen1 RNPs (SHRNPs) whose assembly is strictly dependent on HIV-1 expression. SHRNPs are distinct from stress granules and processing bodies, are preferentially formed during oxidative stress and are found to be in equilibrium with translating polysomes. Moreover, SHRNPs are stable, and the association between Staufen1 and vRNA was found to be evident in these and other types of RNPs. We demonstrate that following Staufen1 depletion, apparent supraphysiologic-sized SHRNP foci are formed in the cytoplasm and in which Gag, vRNA and the residual Staufen1 accumulate. The depletion of Staufen1 resulted in reduced Gag levels and deregulated the assembly of newly synthesized virions, which were found to contain several-fold increases in vRNA, Staufen1 and other cellular proteins. This work provides new evidence that Staufen1-containing HIV-1 RNPs preferentially form over other cellular silencing foci and are involved in assembly, localization and encapsidation of vRNA.

Descripción: Two new varieties, Annulohypoxylon moriforme var. macrosporum and Hypoxylon investiens var. magnisporum are proposed; Annulohypoxylon nitens, Hypoxylon crocopeplum, H. subrutilum and H. rubiginosum var. microsporum are described as new records from Argentina. A dichotomous key to hypoxyloid taxa so far known from Argentina is presented.

Descripción: Fil:Burzyn, P. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.

Descripción: The chemical synthesis of nitrogen-doped titanium dioxide (N-TiO 2) is explored in an attempt to understand the mechanisms of doping. Urea is used as precursor in a sol gel synthesis of N-TiO 2. Chemical and structural changes during thermal treatment of the precursors were followed by several techniques. The effect of doping on band gap, morphology, and microstructure was also determined. The byproducts produced during firing correspond to those obtained during urea thermal decomposition. Polynitrogenated colored compounds produced at temperatures below 400°C may act as sensitizer. Incorporation of N in the TiO 2 structure is possible at higher temperatures. Degradation experiments of salicylic acid under UVA and visible light (γ≥400 nm) in the presence of TiO 2 or N-TiO 2 indicate that doping decreases the activity under UVA light, while stable byproducts are produced under visible light. © 2011 Matias Factorovich et al.

Descripción: Despite considerable progress in our understanding of the interplay between immune and endocrine systems, the role of thyroid hormones and their receptors in the control of adaptive immunity is still uncertain. Here, we investigated the role of thyroid hormone receptor (TR) β 1 signaling in modulating dendritic cell (DC) physiology and the intracellular mechanisms underlying these immunoregulatory effects. Exposure of DCs to triiodothyronine (T 3 ) resulted in a rapid and sustained increase in Akt phosphorylation independently of phosphatidylinositol 3-kinase activation, which was essential for supporting T 3 -induced DC maturation and interleukin (IL)-12 production. This effect was dependent on intact TRβ 1 signaling as small interfering RNA-mediated silencing of TRβ 1 expression prevented T 3 -induced DC maturation and IL-12 secretion as well as Akt activation and IκB-ε degradation. In turn, T 3 up-regulated TRβ 1 expression through mechanisms involving NF-κB, suggesting an autocrine regulatory loop to control hormone-dependent TRβ 1 signaling. These findings were confirmed by chromatin immunoprecipitation analysis, which disclosed a new functional NF-κB consensus site in the promoter region of the TRB1 gene. Thus, a T 3 -induced NF-κB-dependent mechanism controls TRβ 1 expression, which in turn signals DCs to promote maturation and function via an Akt-dependent but PI3K-independent pathway. These results underscore a novel unrecognized target that regulates DC maturation and function with critical implications in immunopathology at the crossroads of the immune-endocrine circuits. © 2010 by The American Society for Biochemistry and Molecular Biology, Inc.

Descripción: The ASR (for ABA/water stress/ripening) protein family, first described in tomato as nuclear and involved in adaptation to dry climates, is widespread in the plant kingdom, including crops of high agronomic relevance. We show both nuclear and cytosolic localization for ASR1 (the most studied member of the family) in histological plant samples by immunodetection, typically found in small proteins readily diffusing through nuclear pores. Indeed, a nuclear localization was expected based on sorting prediction software, which also highlight a monopartite nuclear localization signal (NLS) in the primary sequence. However, here we prove that such an "NLS" of ASR1 from tomato is dispensable and non-functional, being the transport of the protein to the nucleus due to simple diffusion across nuclear pores. We attribute such a targeting deficiency to the misplacing in that cryptic NLS of two conserved contiguous lysine residues. Based on previous in vitro experiments regarding quaternary structure, we also carried out live cell imaging assays through confocal microscopy to explore dimer formation in planta. We found homodimers in both the cytosol and the nucleus and demonstrated that assembly of both subunits together can occur in the cytosol, giving rise to translocation of preformed dimers. The presence of dimers was further corroborated by means of in vivo crosslinking of nuclei followed by SDS-PAGE. © 2012 Ricardi et al.

Descripción: Glucocorticoid receptor (GR) is cytoplasmic in the absence of ligand and localizes to the nucleus after steroid binding. Previous evidence demonstrated that the hsp90-based heterocomplex bound to GR is required for the efficient retrotransport of the receptor to the nuclear compartment. We examined the putative association of GR and its associated chaperone heterocomplex with structures of the nuclear pore. We found that importin β and the integral nuclear pore glycoprotein Nup62 interact with hsp90, hsp70, p23, and the TPR domain proteins FKBP52 and PP5. Nup62 and GR were able to interact in a more efficient manner when chaperoned by the hsp90-based heterocomplex. Interestingly, the binding of hsp70 and p23 to Nup62 does not require the presence of hsp90, whereas the association of FKBP52 and PP5 is hsp90 dependent, as indicated by the results of experiments where the hsp90 function was disrupted with radicicol. The ability of both FKBP52 and PP5 to interact with Nup62 was abrogated in cells overexpressing the TPR peptide. Importantly, GR cross-linked to the hsp90 heterocomplex was able to translocate to the nucleus in digitonin-permeabilized cells treated with steroid, suggesting that GR could pass through the pore in its untransformed state. Copyright © 2009, American Society for Microbiology. All Rights Reserved.

Descripción: We investigate the importance of relativistic effects on NMR shielding constants and chemical shifts of linear HgL2 (L = Cl, Br, I, CH 3) compounds using three different relativistic methods: the fully relativistic four-component approach and the two-component approximations, linear response elimination of small component (LR-ESC) and zeroth-order regular approximation (ZORA). LR-ESC reproduces successfully the four-component results for the C shielding constant in Hg(CH3)2 within 6 ppm, but fails to reproduce the Hg shielding constants and chemical shifts. The latter is mainly due to an underestimation of the change in spin-orbit contribution. Even though ZORA underestimates the absolute Hg NMR shielding constants by ∼2100 ppm, the differences between Hg chemical shift values obtained using ZORA and the four-component approach without spin-density contribution to the exchange-correlation (XC) kernel are less than 60 ppm for all compounds using three different functionals, BP86, B3LYP, and PBE0. However, larger deviations (up to 366 ppm) occur for Hg chemical shifts in HgBr 2 and HgI2 when ZORA results are compared with four-component calculations with non-collinear spin-density contribution to the XC kernel. For the ZORA calculations it is necessary to use large basis sets (QZ4P) and the TZ2P basis set may give errors of ∼500 ppm for the Hg chemical shifts, despite deceivingly good agreement with experimental data. A Gaussian nucleus model for the Coulomb potential reduces the Hg shielding constants by ∼100-500 ppm and the Hg chemical shifts by 1-143 ppm compared to the point nucleus model depending on the atomic number Z of the coordinating atom and the level of theory. The effect on the shielding constants of the lighter nuclei (C, Cl, Br, I) is, however, negligible. © 2011 American Institute of Physics.

Descripción: We use ring-polymer-molecular-dynamics (RPMD) techniques and the semi-empirical q-TIP4P/F water model to investigate the relationship between hydrogen bond connectivity and the characteristics of nuclear position fluctuations, including explicit incorporation of quantum effects, for the energetically low lying isomers of the prototype cluster [H2O] 8 at T = 50 K and at 150 K. Our results reveal that tunneling and zero-point energy effects lead to sensible increments in the magnitudes of the fluctuations of intra and intermolecular distances. The degree of proton spatial delocalization is found to map logically with the hydrogen-bond connectivity pattern of the cluster. Dangling hydrogen bonds exhibit the largest extent of spatial delocalization and participate in shorter intramolecular O-H bonds. Combined effects from quantum and polarization fluctuations on the resulting individual dipole moments are also examined. From the dynamical side, we analyze the characteristics of the infrared absorption spectrum. The incorporation of nuclear quantum fluctuations promotes red shifts and sensible broadening relative to the classical profile, bringing the simulation results in much more satisfactory agreement with direct experimental information in the mid and high frequency range of the stretching band. While RPMD predictions overestimate the peak position of the low frequency shoulder, the overall agreement with that reported using an accurate, parameterized, many-body potential is reasonable, and far superior to that one obtains by implementing a partially adiabatic centroid molecular dynamics approach. Quantum effects on the collective dynamics, as reported by instantaneous normal modes, are also discussed. © 2013 AIP Publishing LLC.

Descripción: The role of oxidative stress in prostate cancer has been increasingly recognised. Acute and chronic inflammations generate reactive oxygen species that result in damage to cellular structures. Haeme oxygenase-1 (HO-1) has cytoprotective effects against oxidative damage. We hypothesise that modulation of HO-1 expression may be involved in the process of prostate carcinogenesis and prostate cancer progression. We thus studied HO-1 expression and localisation in 85 samples of organ-confined primary prostate cancer obtained via radical prostatectomy (Gleason grades 4-9) and in 39 specimens of benign prostatic hyperplasia (BPH). We assessed HO-1 expression by immunohistochemical staining. No significant difference was observed in the cytoplasmic positive reactivity among tumours (84%), non-neoplastic surrounding parenchyma (89%), or BPH samples (87%) (P=0.53). Haeme oxygenase-1 immunostaining was detected in the nuclei of prostate cancer cells in 55 of 85 (65%) patients but less often in non-neoplastic surrounding parenchyma (30 of 85, 35%) or in BPH (9 of 39, 23%) (P<0.0001). Immunocytochemical and western blot analysis showed HO-1 only in the cytoplasmic compartment of PC3 and LNCaP prostate cancer cell lines. Treatment with hemin, a well-known specific inducer of HO-1, led to clear nuclear localisation of HO-1 in both cell lines and highly induced HO-1 expression in both cellular compartments. These findings have demonstrated, for the first time, that HO-1 expression and nuclear localisation can define a new subgroup of prostate cancer primary tumours and that the modulation of HO-1 expression and its nuclear translocation could represent new avenues for therapy. © 2007 Cancer Research UK.

Descripción: Insertion of factor MudJ in the intergenic region between divergent genes yrfF and yrfE, at centisome 76 in the genome of Salmonella enterica serovar Typhimurium LT2, confers the characteristics recently described for mucM mutants, i.e. mucoidy and resistance to mecillinam. Cloning of the intergenic region plus either the yrfF or the yrfE gene in a multicopy plasmid showed that only the plasmid carrying the yrfF gene complemented mucM mutants, thus suggesting that mucM mutations are in fact yrfF mutations. A null yrfF mutation obtained by insertion of a kanamycin cassette into the yrfF open reading frame (yrfF28::Kan) produced abortive colonies when transduced to a wild-type strain but was normally accepted by rcsB, rcsC or yojN strains. Neither mutations preventing synthesis of the capsular exopolysaccharide colanic acid (cps, galE) nor rcsA mutations, which reduce expression of cps genes, conferred tolerance to the lethal yrfF28::Kan mutation. Spontaneous suppressor mutations arose very frequently in abortive yrfF28::Kan colonies, and all of them affected either rcsC, yojN, or rcsB genes. Thus, the lethal effect caused by inactivation of gene yrfF appears to be mediated by a function that is dependent on the rcsC-yojN-rcsB phosphorelay system but does not involve synthesis of colanic acid. © 2003 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.

Descripción: We prove that a polynomial f ∈ R [x, y] with t non-zero terms, restricted to a real line y = a x + b, either has at most 6 t - 4 zeros or vanishes over the whole line. As a consequence, we derive an alternative algorithm for deciding whether a linear polynomial y - a x - b ∈ K [x, y] divides a lacunary polynomial f ∈ K [x, y], where K is a real number field. The number of bit operations performed by the algorithm is polynomial in the number of non-zero terms of f, in the logarithm of the degree of f, in the degree of the extension K / Q and in the logarithmic height of a, b and f. © 2009 Elsevier Ltd. All rights reserved.

Descripción: In this work, the modeling of plate tectonic processes associated with crustal deformation through a numerical framework for non-collisional Andean type orogens is presented. The main objectives of the numerical framework are to develop a numerical model in order to represent large-scale deformation in Andean type subduction zones, to include appropriate physical and mathematical laws that describe the behavior of the lithosphere, to model surface erosion taking into account dominant winds direction and the synorogenic topography of the orogen as the crustal erosion caused by friction between the subducting and the overriding plate and to include isostatic compensation behavior taking into account flexural rigidity. © 2005 Asociación Geológica Argentina.

Descripción: Double-arcing is a phenomenon that occurs when a transferred arc, flowing inside an electrically insulated nozzle, breaks into two separate arcs: one that connects the cathode with the nozzle, and another that connects the nozzle with the anode. Experimental evidence suggests that the reason for double-arcing is a Townsend like breakdown occurring in the thin space-charge layer, which separates the plasma from the metallic nozzle, due to the high voltage drop across it. Breakdown phenomena in a gas between metallic electrodes have been extensively studied; however the present case involves breakdown of a high-temperature gas between one electrode (the nozzle) and a plasma boundary. A 1-D model of the gas breakdown development in the space-charge layer contiguous to the nozzle of a cutting arc torch operated with oxygen is reported. The dynamics of the discharge is analyzed. The kinetic scheme includes processes of ionization of heavy particles by electron impact, electron attachment, electron-ion recombination and ion-ion recombination.

Descripción: The dynamics of open balloons in an atmosphere may be studied with a body-fluid coupled model. A numerical approach is required to solve the corresponding equation set. Solutions under different conditions are obtained here for the vertical and one horizontal direction. Relevant dynamical features during ascent, flotation, and descent depend on balloon thermodynamics, wind, air small-scale turbulence, and perturbations to the background atmosphere. After analysis of the results it is found that approximate analytical solutions may be found in certain cases. The effect of nonlinear drag on balloon oscillation period and damping near flotation is evaluated. © 2003 American Institute of Physics.

Descripción: Fil:Carlo, G. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.

Descripción: We consider a family of polynomial systems which arises in the analysis of the stationary solutions of a standard discretization of certain semi-linear second-order parabolic partial differential equations. We prove that this family is well-conditioned from the numeric point of view, and ill-conditioned from the symbolic point of view. We exhibit a polynomial-time numeric algorithm solving any member of this family, which significantly contrasts the exponential behavior of all known symbolic algorithms solving a generic instance of this family of systems. © 2005 Elsevier Inc. All rights reserved.