Showing papers by "National University of Cuyo published in 2006"
TL;DR: It is proposed that the process of growth promotion triggered by A. brasilense inoculation involves a signaling pathway that has ethylene as a central, positive regulator.
Abstract: Tomato seeds were inoculated with the plant growth–promoting rhizobacteria Azospirillum brasilense FT326, and changes in parameters associated with plant growth were evaluated 15 days after inoculation. Azospirilla were localized on roots and within xylematic tissue. An increase in shoot and root fresh weight, main root hair length, and root surface indicated that inoculation with A. brasilense FT 326 resulted in plant growth improvement. The levels of indole-3-acetic acid (IAA) and ethylene, two of the phytohormones related to plant growth, were higher in inoculated plants. Exogenously supplied ethylene mimicked the effect of inoculation, and the addition of an inhibitor of its synthesis or of its physiological activity completely blocked A. brasilense growth promotion. Based on our results, we propose that the process of growth promotion triggered by A. brasilense inoculation involves a signaling pathway that has ethylene as a central, positive regulator.
126 citations
TL;DR: A systematic analysis addressing how macrophages kill ‘non‐pathogenic’ Mycobacterium smegmatis found that map kinase p38 is a crucial regulator of all processes investigated, except NO synthesis, that facilitated the host for some functions while being usurped by live bacteria for others.
Abstract: After internalization into macrophages non-pathogenic mycobacteria are killed within phagosomes. Pathogenic mycobacteria can block phagosome maturation and grow inside phagosomes but under some conditions can also be killed by macrophages. Killing mechanisms are poorly understood, although phago-lysosome fusion and nitric oxide (NO) production are implicated. We initiated a systematic analysis addressing how macrophages kill 'non-pathogenic'Mycobacterium smegmatis. This system was dynamic, involving periods of initial killing, then bacterial multiplication, followed by two additional killing stages. NO synthesis represented the earliest killing factor but its synthesis stopped during the first killing period. Phagosome actin assembly and fusion with late endocytic organelles coincided with the first and last killing phase, while recycling of phagosome content and membrane coincided with bacterial growth. Phagosome acidification and acquisition of the vacuolar (V) ATPase followed a different pattern coincident with later killing phases. Moreover, V-ATPase localized to vesicles distinct from classical late endosomes and lysosomes. Map kinase p38 is a crucial regulator of all processes investigated, except NO synthesis, that facilitated the host for some functions while being usurped by live bacteria for others. A mathematical model argues that periodic high and low cellular killing activity is more effective than is a continuous process.
119 citations
TL;DR: It is proposed that the VacA-dependent isolation of the H. pylori-containing vacuole from bactericidal components of the lysosomal pathway promotes bacterial survival and contributes to the persistence of infection.
Abstract: Helicobacter pylori colonizes the gastric epithelium of at least 50% of the world's human population, playing a causative role in the development of chronic gastritis, peptic ulcers, and gastric adenocarcinoma. Current evidence indicates that H. pylori can invade epithelial cells in the gastric mucosa. However, relatively little is known about the biology of H. pylori invasion and survival in host cells. Here, we analyze both the nature of and the mechanisms responsible for the formation of H. pylori's intracellular niche. We show that in AGS cells infected with H. pylori, bacterium-containing vacuoles originate through the fusion of late endocytic organelles. This process is mediated by the VacA-dependent retention of the small GTPase Rab7. In addition, functional interactions between Rab7 and its downstream effector, Rab-interacting lysosomal protein (RILP), are necessary for the formation of the bacterial compartment since expression of mutant forms of RILP or Rab7 that fail to bind each other impaired the formation of this unique bacterial niche. Moreover, the VacA-mediated sequestration of active Rab7 disrupts the full maturation of vacuoles as assessed by the lack of both colocalization with cathepsin D and degradation of internalized cargo in the H. pylori-containing vacuole. Based on these findings, we propose that the VacA-dependent isolation of the H. pylori-containing vacuole from bactericidal components of the lysosomal pathway promotes bacterial survival and contributes to the persistence of infection.
112 citations
TL;DR: Luccioni et al. as discussed by the authors presented a study of Guzman's work at the Centro Cientifico Tecnologico Conicet -Tucuman, Argentina.
105 citations
TL;DR: Results indicate that P. argentina has a greater tolerance to water deficit during plant establishment, which is consistent with the previous findings that have described P. Argentina as a xerophyte able to cope with harsh sand-dune conditions, and P. alpataco as a phreatophytic species with more mesomorphic features.
102 citations
TL;DR: CAMP-elicited exocytosis was sensitive to anti-α-SNAP, anti-NSF, and anti-Rab3A antibodies, to intra-acrosomal Ca2+ chelators, and to botulinum toxins but was resistant to cAMP-dependent protein kinase blockers.
93 citations
TL;DR: It is speculated that Rab22a controls the transport of the transferrin receptor from sorting to recycling endosomes and depletion by small interfering RNA disorganized the perinuclear recycling center and strongly inhibited transferrin recycling.
Abstract: Rab22a is a member of the Rab family of small GTPases that localizes in the endocytic pathway. In CHO cells, expression of canine Rab22a (cRab22a) causes a dramatic enlargement of early endocytic compartments. We wondered whether transferrin recycling is altered in these cells. Expression of the wild-type protein and a GTP hydrolysis-deficient mutant led to the redistribution of transferrin receptor to large cRab22a-positive structures in the periphery of the cell and to a significant decrease in the plasma membrane receptor. Kinetic analysis of transferrin uptake indicates that internalization and early recycling were not affected by cRab22a expression. However, recycling from large cRab22a-positive compartments was strongly inhibited. A similar effect on transferrin transport was observed when human but not canine Rab22a was expressed in HeLa cells. After internalization for short periods of time (5 to 8 min) or at a reduced temperature (16°C), transferrin localized with endogenous Rab22a in small vesicles that did not tubulate with brefeldin A, suggesting that the endogenous protein is present in early/sorting endosomes. Rab22a depletion by small interfering RNA disorganized the perinuclear recycling center and strongly inhibited transferrin recycling. We speculate that Rab22a controls the transport of the transferrin receptor from sorting to recycling endosomes.
89 citations
TL;DR: Evidence indicating that K562 cells present a high basal level of autophagy, and that there is an association between MVBs and autophagosomes, is discussed, suggesting a role for the autophagic pathway in the maturation process of this cell type.
Abstract: During reticulocyte maturation, hematopoietic progenitors undergo numerous changes to reach the final functional stage which concludes with the release of reticulocytes and erythrocytes into circulation. During this process some proteins, which are not required in the mature stage, are sequestered in the internal vesicles present in multivesicular bodies (MVBs). These small vesicles are known as exosomes because they are released into the extracellular medium by fusion of the MVB with the plasma membrane. Interestingly, during this maturation process some organelles, such as mitochondria and endoplasmic reticulum, are wrapped in double membrane vacuoles and degraded via autophagy. We have demonstrated in human leukemic K562 cells a role for calcium and Rab11 in the biogenesis of MVBs and exosome release. Here we discuss evidence indicating that K562 cells present a high basal level of autophagy, and that there is an association between MVBs and autophagosomes, suggesting a role for the autophagic pathway in the maturation process of this cell type.
84 citations
Journal Article•
82 citations
TL;DR: Six SSR loci, previously developed for grapevine, were analyzed to evaluate the genetic variability and cultivar relatedness in a collection of 25 autochthonous Vitis vinifera varieties from Peruand Argentina, revealing a general pattern of shared morphological and enological traits.
78 citations
TL;DR: Although T TF1 appears to fulfill only a morphogenic function in the ventral telencephalon, once this function is satisfied in the hypothalamus, TTF1 remains active as part of the transcriptional machinery controlling female sexual development.
Abstract: Thyroid transcription factor 1 (TTF1) [also known as Nkx2.1 (related to the NK-2 class of homeobox genes) and T/ebp (thyroid-specific enhancer-binding protein)], a homeodomain gene required for basal forebrain morphogenesis, remains expressed in the hypothalamus after birth, suggesting a role in neuroendocrine function. Here, we show an involvement of TTF1 in the control of mammalian puberty and adult reproductive function. Gene expression profiling of the nonhuman primate hypothalamus revealed that TTF1 expression increases at puberty. Mice in which the Ttf1 gene was ablated from differentiated neurons grew normally and had normal basal ganglia/hypothalamic morphology but exhibited delayed puberty, reduced reproductive capacity, and a short reproductive span. These defects were associated with reduced hypothalamic expression of genes required for sexual development and deregulation of a gene involved in restraining puberty. No extrapyramidal impairments associated with basal ganglia dysfunction were apparent. Thus, although TTF1 appears to fulfill only a morphogenic function in the ventral telencephalon, once this function is satisfied in the hypothalamus, TTF1 remains active as part of the transcriptional machinery controlling female sexual development.
TL;DR: It is argued that the phagosome cAMP-PKA system behaves as a molecular switch that regulates phagosomal actin and maturation in macrophages.
Abstract: We showed recently that actin assembly by phagosomal membranes facilitates fusion with late endocytic organelles in macrophages. Moreover, lipids that induced phagosomal actin also stimulated this fusion process. In macrophages infected with pathogenic mycobacteria actin-stimulatory lipids led to an increase in pathogen destruction, whereas inhibitors facilitated their growth. A model was proposed whereby phagosomal membrane actin assembly provides tracks for lysosomes to move towards phagosomes, thereby facilitating fusion. Here, we investigated how cAMP affected phagosomal actin assembly in vitro, and phagosomal actin, acidification and late fusion events in J774 macrophages. Latex bead phagosomes are shown to possess adenylyl cyclase activity, which synthesizes cAMP, and phosphodiesterase activity, which degrades cAMP. The system is regulated by protein kinase A (PKA). Increasing cAMP levels inhibited, whereas decreasing cAMP levels stimulated, actin assembly in vitro and within cells. Increasing cAMP levels also inhibited phagosome-lysosome fusion and acidification in cells, whereas reducing cAMP had the opposite effect. High cAMP levels induced an increase in intraphagosomal growth in macrophages of both the non-pathogenic Mycobacterium smegmatis and the pathogenic Mycobacterium tuberculosis, whereas low cAMP levels or inhibition of PKA correlated with increased bacterial destruction. We argue that the phagosome cAMP-PKA system behaves as a molecular switch that regulates phagosome actin and maturation in macrophages.
TL;DR: Although drugs used to disrupt actin and intermediate filaments had no effect on the segregation of GM1, it was found that disulfide‐bonded proteins played a significant role in sub‐domain segregation.
Abstract: Lipid rafts, membrane sub-domains enriched in sterols and sphingolipids, are controversial because demonstrations of rafts have often utilized fixed cells. We showed in living sperm that the ganglioside G(M1) localized to a micron-scale membrane sub-domain in the plasma membrane overlying the acrosome. We investigated four models proposed for membrane sub-domain maintenance. G(M1) segregation was maintained in live sperm incubated under non-capacitating conditions, and after sterol efflux, a membrane alteration necessary for capacitation. The complete lack of G(M1) diffusion to the post-acrosomal plasma membrane (PAPM) in live cells argued against the transient confinement zone model. However, within seconds after cessation of sperm motility, G(M1) dramatically redistributed several microns from the acrosomal sub-domain to the post-acrosomal, non-raft sub-domain. This redistribution was not accompanied by movement of sterols, and was induced by the pentameric cholera toxin subunit B (CTB). These data argued against a lipid-lipid interaction model for sub-domain maintenance. Although impossible to rule out a lipid shell model definitively, mice lacking caveolin-1 maintained segregation of both sterols and G(M1), arguing against a role for lipid shells surrounding caveolin-1 in sub-domain maintenance. Scanning electron microscopy of sperm freeze-dried without fixation identified cytoskeletal structures at the sub-domain boundary. Although drugs used to disrupt actin and intermediate filaments had no effect on the segregation of G(M1), we found that disulfide-bonded proteins played a significant role in sub-domain segregation. Together, these data provide an example of membrane sub-domains extreme in terms of size and stability of lipid segregation, and implicate a protein-based membrane compartmentation mechanism.
TL;DR: It is confirmed that the co-expression of HR with Her-2/neu is infrequent, and that these patients presented both a shorter disease free survival and overall survival, and the aromatase inhibitor anastrozole appears to be an effective endocrine treatment in HR+ patients, irrespective of the Her- 2/neU status.
TL;DR: This work studies at the molecular level these two different faces of the autophagy process in pathogen life in order to elucidate the intricate routes modulated by the microorganisms as survival strategies.
Abstract: In the world of pathogen-host cell interactions, the autophagic pathway has been recently described as a component of the innate immune response against intracellular microorganisms. Indeed, some bacterial survival mechanisms are hampered when this process is activated. Mycobacterium tuberculosis infection of macrophages, for example, is impaired upon autophagy induction and the bacterial phagosomes are redirected to autophagosomes. On the other hand, pathogens like Coxiella burnetii are benefited by this cellular response and subvert the autophagy process resulting in a more efficient replication. We study at the molecular level these two different faces of the autophagy process in pathogen life in order to elucidate the intricate routes modulated by the microorganisms as survival strategies.
TL;DR: Present observations indicate that the LC network changes markedly with aging, and results suggest that immunological defense of the oral tissue might be compromised in old age.
Journal Article•
TL;DR: The current paper overviews the diversity of symbiotic associations of P. canaliculata, and updates the information on the prokaryotic symbiont, which is most likely a cyanobacterium.
Abstract: Pomacea canaliculata (Lamarck 1822) occurs mainly in lentic habitats throughout the lower Amazon basin and the Plata basin (Hylton-Scott, 1958; Martín et al., 2001). This Neotropical species has been introduced (ca. 1980) to several South East Asian countries for aquaculture, and has become a serious pest for rice and other crops (Halwart, 1994). Many Pacific islands are currently included in the invaded area (Cowie, 2002). In a previous previous publication we have presented preliminary evidence for a symbiotic association of Pomacea canaliculata and of other Neotropical Ampullariidae with a large and pigmented prokaryotic symbiont within specific cells of the midgut gland of this snail (Castro-Vazquez et al., 2002). The current paper overviews the diversity of symbiotic associations of P. canaliculata, and updates the information on the prokaryotic symbiont, which is most likely a cyanobacterium. What do we put in the term “symbiosis”?
TL;DR: In this paper, a numerical study on craters formed by explosive loads located on the soil surface is presented, and the soil parameters used in the numerical model, as well as the analysis procedure, were validated against experimental observations of the crater diameters.
Abstract: Explosives are commonly used in terrorist attacks and the craters formed by blast waves can be used as a diagnostic tool. For example, the focus of the explosion and the mass of the explosive used in the attack can be deduced by examining the location, geometry, and dimensions of the crater. However, studies about craters produced by explosions on or above ground level, which would be the case when the explosive charge is situated in a vehicle, are rarely found in the open technical literature. In this paper, a numerical study on craters formed by explosive loads located on the soil surface is presented. The soil parameters used in the numerical model, as well as the analysis procedure, were validated against experimental observations of the crater diameters. Results of numerical tests performed with different amounts of explosive on the soil surface are presented. Moreover, the effect of elevation of the center of energy release of explosive loads located on the soil surface is analyzed and discussed. Simple predictive equations for the crater diameter are presented.
TL;DR: It was concluded that ICTX is active against T. cruzi and may act by multiple mechanisms, and this novel icetexane diterpene may be a good candidate for therapeutic use against Chagas' disease.
TL;DR: In this paper, the effect of soil damping on the most important design variables in the seismic response of building structures with prismatic rectangular foundations was quantified using a soil-structure interaction model.
TL;DR: Algorithm for construction of a distance function from the zero-level set, in such a way that mass is conserved on arbitrary unstructured meshes, which is consistent with the hyperbolic character of the distance equation and can be localized on a narrow band close to the interface, saving computing effort.
Abstract: The level set method is becoming increasingly popular for the simulation of several problems that involve interfaces. The level set function is advected by some velocity field, with the zero-level set of the function defining the position of the interface. The advection distorts the initial shape of the level set function, which needs to be re-initialized to a smooth function preserving the position of the zero-level set. Many algorithms re-initialize the level set function to (some approximation of) the signed distance from the interface. Efficient algorithms for level set redistancing on Cartesian meshes have become available over the last years, but unstructured meshes have received little attention. This presentation concerns algorithms for construction of a distance function from the zero-level set, in such a way that mass is conserved on arbitrary unstructured meshes. The algorithm is consistent with the hyperbolic character of the distance equation (∥d∥=1) and can be localized on a narrow band close to the interface, saving computing effort. The mass-correction step is weighted according to local mass differences, an improvement over usual global rebalancing techniques.
TL;DR: The relations among the varieties based on AFLP data were significantly correlated with those based on agronomic and morphological characters, suggesting that the 2 systems give similar estimates of genetic relations amongThe varieties.
Abstract: We assessed the genetic diversity in Trichloris crinita (Poaceae) varieties from South America, using AFLPs, morphological characters, and quantitative agronomic traits. Owing to the importance of this species for range grazing, we first characterized the varieties based on forage productivity. Biomass production varied 9 fold among the materials evaluated. Analysis of AFLP fingerprints allowed the discrimination of all varieties with a few selected primer combinations. Pair-wise genetic similarities, using marker data, ranged from 0.31 to 0.92 (Jaccard coefficients). Marker-based unweighted pair group method with arithmetic averaging (UPGMA) cluster analysis did not show geographical clustering, but rather grouped the varieties according to their biomass production. We identified 18 markers associated with biomass production, of which 8 showed complete correlation (r = 1.00) with this trait. These DNA markers can be used to assist selection for high forage productivity in T. crinita. Cluster analysis usi...
01 Jan 2006
TL;DR: In this paper, el indice de color como medida de la calidad del ajo picado was determinado, based on the color of the ajo, e.g., a color siempre inferior a 2, partiendo de valores poco mayores a 5.
Abstract: Se ha determinado el indice de color como medida de la calidad del ajo picado Para ello, se emplearon las cultivares Perla, Gostoso, Sureno, Morado, Castano, Norteno, Nieve, Lican, Fuego y Union Los bulbos seleccionados, pelados y picados se envasaron en bolsas de poliamida coextrusada con polietileno de 80 micrones y se conservaron a 0±2°C y 85±5% de humedad relativa Semanalmente, se digitalizaron las muestras mediante escaner calibrado para la identificacion del valor medio de color por los sistemas RGB y Lab, con muestreo fue al azar Se calculo el indice de color y diseno la paleta de colores Se realizo evaluacion visual para determinar el fin de la vida util, mediante panel semi entrenado (n=8) relacionando los resultados con el Indice de Color Algunas variedades, como Union y Nieve, presentaron una vida util prolongada (90 dias) con un indice de color siempre inferior a 2, partiendo de valores poco mayores a 05 Otras cultivares, como Perla, Lican, Castano y Morado, a los 22 dias presentaron indice de color cercanos a 3 El indice de color de 2 coincidio con el limite de la vida util visual En base este, es posible desarrollar una cartilla de colores para el uso en la determinacion de vida util de ajo picado
TL;DR: In this paper, the magnetic properties of MnAs epilayers have been investigated for two different substrate orientations GaAs(100) and GaAs (111), and the magnetization reversal under magnetic field at low temperatures, determining the anisotropy of the films.
Abstract: The magnetic properties of MnAs epilayers have been investigated for two different substrate orientations GaAs(100) and GaAs(111). We have analyzed the magnetization reversal under magnetic field at low temperatures, determining the anisotropy of the films. The results, based on the shape of the magnetization loops, suggest a domain movement mechanism for both types of samples. The temperature dependence of the coercivity of the films has been also examined, displaying a generic anomalous reentrant behavior at T>200 K. This feature is independent of the substrate orientation and films thickness and may be associated to the appearance of pinning centers due to the nucleation of the beta phase at high temperatures.
TL;DR: A new approach was developed, which is a foundation of a bridge between bond graphs and CFD, which can be shown that the system total energy can be represented as a three-port IC-field.
TL;DR: In breast cancer patients treated with standard adjuvant therapy with tamoxifen, the expression of steroid hormone receptors appears inversely correlated with Her2/neu, and the disease free survival of the patients co-expressing HR and Her2-2-neu was significantly lower than those expressing HR but lacking of Her2 /neu.
TL;DR: In this article, a multiplex PCR assay was designed to check aggregative adherence fimbriae (AAF/I and AAF/II), a transcriptional activator (aggR gene), the enteroaggregative heat-stable enterotoxin EAST1 (astA gene) and a cytotoxin (Pet).
Abstract: Enteroaggregative Escherichia coli (EAEC) has been implicated in sporadic diarrhea in children and adults and has been identified as the cause of several outbreaks worldwide. The HEp-2 test remains the gold standard for identification of this pathotype. A 60-65 MDa plasmid encodes the aggregative adherence fimbriae (AAF/I and AAF/II), a transcriptional activator (aggR gene), the enteroaggregative heat-stable enterotoxin EAST1 (astA gene) and a cytotoxin (Pet). The standard assay for EAEC is performed only in research laboratories, because it is expensive, labor intensive and time-consuming. The Polymerase Chain Reaction (PCR) offers the possibility of rapid diagnosis. In the current study, a multiplex PCR assay which checks aggR and astA genes was designed. Eigthy-eight E. coli strains, isolated from children with acute diarrhea in Mendoza, Argentina, were characterized by the reference method (HEp-2 assay), and by aggR-astA PCR. A strong correlation between the presence of the specific marker aggR and the reference test was found. The astA gene had a similar distribution between aggregative and localized strains, indicating that this gene could not be considered as a marker of EAEC. We conclude that aggR may be used to identify EAEC, using the PCR method as a screening test.
Journal Article•
TL;DR: In this paper, the authors present a registro de emplazamientos and canteras and talleres utilizados for the explotation of materias primas liticas.
Abstract: El Valle de Potrerillos (1.400 m snm) fue intensamente ocupado durante el Holoceno tardio por agricultores
que usaron pequenas casas semi-subterraneas (Sitio Gendarmeria Casas 1 y 2). En el trabajo se presenta el registro
de estos emplazamientos y de las canteras y talleres utilizados para la explotacion de materias primas liticas.
Una cantera taller de riolitas y basaltos en el propio valle (Paleomedanos), y una de rocas criptocristalinas en el
Piedemonte de la Precordillera donde se localizaron abrigos rocosos que muestran una secuencia de ocupacion
de 2.300 a 1.000 C14 anos AP (Los Conitos). La evaluacion de los materiales liticos de acuerdo a su procedencia
permite reconstruir secuencias de produccion que refieren episodios especificos en diferentes localizaciones.
Las diferencias en las propiedades organizacionales de la tecnologia se han vinculado a factores como el crecimiento
de poblacion, cambios en la subsistencia y sistema de asentamiento entre el Holoceno medio y tardio.
Esto involucra un proceso de intensificacion en la explotacion de recursos y una reduccion en la movilidad.
TL;DR: SLO-permeabilized macrophages likely constitute a useful tool to identify new molecules involved in regulating transport along the phagocytic pathway and show the requirement of a functional Rab11 for the retrieval to the plasma membrane of phagosomal content.
TL;DR: In this article, a simulation of the ferromagnetic resonance response of magnetic nanoparticles with a uniaxial anisotropy considerably larger than the microwave excitation frequency is presented.
Abstract: We present in this study computational simulations of the ferromagnetic resonance response of magnetic nanoparticles with a uniaxial anisotropy considerably larger than the microwave excitation frequency (in field units). The particles are assumed to be randomly oriented in a two dimensional lattice, and are coupled by dipolar interactions through an effective demagnetization field, which is proportional to the packing fraction. We have included in the model fluctuations in the anisotropy field (HK) and allowed variations in the demagnetizing field. We then analyzed the line shape and line intensity as a function of both fields. We have found that when HK is increased the line shape changes drastically, with a structure of two lines appearing at high fields. The line intensity has a maximum when HK equals the frequency gap and decreases considerably for larger values of the anisotropy. The effects of fluctuations in HK and variations in the packing fraction have been also studied. Comparison with experimental data shows that the overall observed behavior is dominated by the particles with lower anisotropy.