A parameterization approach for Equation of State models: The case of Water-Hydrocarbon binary systems Ramello, Juan Ignacio; Rodriguez Reartes, Sabrina Belen; Cismondi Duarte, Martín; Zabaloy, Marcelo Santiago The water-hydrocarbon systems are highly asymmetric. The reproduction of their experimental fluid phase equilibria over wide ranges of conditions by models of the Equation of State (EOS) type is challenging. The EOS has to be flexible enough with respect to composition and temperature. On the other hand, special equilibrium information (such us binary critical points whose pressure is found to be locally maximum or minimum when looking at the critical line) may be hard to reproduce. This may be due more to the lack of a proper optimization strategy than to an intrinsic limitation of the model. A better optimization strategy can be obtained first by considering the equations that describe special phase equilibrium points. Another example of such points is a binary liquid-liquid-vapor equilibrium point where one of the liquid phases has, locally, a minimum or a maximum component mole fraction value. In this work we use, on one hand, the mathematical conditions of special phase equilibrium points. For deriving some of such conditions, we resort to the method of implicit derivation. On the other hand, we initialize the interaction parameters to be fitted by forcing the exact reproduction of some binary key coordinates of special phase equilibrium points. Next, we fit the parameters through a completely implicit approach, i.e., by setting up the optimization problem without using equality restrictions. In such a case, some experimentally unknown thermodynamic variables, e.g., a phase composition, become optimization variables together with the interaction parameters. Finally, if required, the level of implicitness of the optimization problem is gradually reduced as the estimates of the interaction parameter values become increasingly accurate. A fully explicit approach requires to repeatedly solve, during the optimization course, the systems of equations corresponding to conventional or special critical or phase equilibrium points. Thus, the explicit approach has a higher chance of presenting convergence problems than the semi-implicit or fully implicit approaches. In this work, we use an equation of state coupled to cubic mixing rules and temperature-dependent interaction parameters. This makes the model highly flexible and capable, in principle, of representing the phase behavior of water-hydrocarbon systems. For such systems, there is a considerable amount of information available in the literature regarding binary critical lines. We consider an important number of water-hydrocarbon binary systems. We evaluate the strengths and limitations of both, the modeling approach and the parameterization strategy.

Advancement on Bacterial Enzyme technology for industries: research and application of novel biocatalysts Cristobal, Hector Antonio; Abate, Carlos Mauricio; Cid, Alicia Graciela; Rajal, Verónica Beatriz A wide range of novel enzymes for biocatalysts adapted to industrial processes have been obtained from extremophile microorganisms. Marine environments possess an enormous microbial biodiversity and potential sources of many biological compounds for the development of exploitable biotechnology. The demand of biocatalysts adapted to extreme conditions (low or high temperatures, acidic or basic pH and high salt concentration) increases in the industry. The enzyme industry worldwide is valued at U$S 5.1 billion and it is predicted to show an annual increase in demand of 63%. Advances in biotechnology, coupled with growing scientific developments, promise technological innovations in a wide range of biotechnological applications for industries, which will be beyond estimation. Many fields of biotechnological studies need to understand the natural mechanisms in biological systems to use this information towards an integrated analysis of genes or proteins expression. In nature, as well as during industrial processes, bacteria are exposed to changes in environmental physico-chemical parameters, which may impair their growth or survival. In this chapter we focus the studies on Shewanella sp. G5, a psychrotolerant bacterium, which exhibits three β-glucosidases. Two of these isozymes were classified under the glycosyl hydrolase families 1 and 3, encoded by bgl-A (EF141823) and bgl (DQ136044) genes. These β-glucosidases may be of interest for winemaking and citrus juice technology processing at low temperatures. The identification of proteins or genes and its expression patterns under different growth conditions (carbon source, culture media and temperature) were studied by proteome analyses. Two-dimensional gel electrophoresis was performed and whole protein pattern of Shewanella sp. G5 revealed that 59 and 55 proteins spots were induced by cellobiose and glucose, respectively. Proteomic analyses showed that Shewanella sp. G5 re-organizes its metabolism in response to all the variables assayed, indicating expression of housekeeping and specific proteins for a particular condition. Determinate proteins spots expression showed increases, which allowed elucidating the quantitative changes relevant in the levels of genes expression. The identification of these proteins spots suggested that different master regulation schemes are involved in response to glucose and cellobiose carbon sources, and were compared with genome sequence data available for Shewanella oneidensis. These results allowed us to establish the optimum growth conditions for production of β-glucosidases, taking into account the greatest induction.

Stellar Structure and Evolution García Berro, Enrique; Althaus, Leandro Gabriel In this chapter the equations of stellar structure are introduced. Up-to-date descriptions of the most relevant microphysics needed to build reliable stellar configurations are also provided. These include the equation of state, nuclear reactions, opacities, and other less frequently discussed physical processes, such as diffusion and radiative levitation. The necessary numerical techniques currently employed to build evolutionary stellar models as well as the otherwise necessary boundary conditions needed to integrate the equations of stellar structure are also addressed. Finally, an overview of the current state-of-the-art modeling is given.

Aetosauria: a clade of armoured pseudosuchians from the Upper Triassic continental beds Desojo, Julia Brenda; Heckert, Andrew B.; Martz, Jeffrey W.; Parker, William G.; Schoch, Rainer; Small, Bryan J.; Sulej, Tomasz Aetosauria is a clade of obligately quadrupedal, heavily armoured pseudosuchians known from Upper Triassic (late Carnian?Rhaetian) strata on every modern continent except Australia and Antarctica. As many as 22 genera and 26 species ranging from 1 to 6 m in length, and with a body mass ranging from less than 10 to more than 500 kg, are known. Aetosauroides scagliai was recently recovered as the most basal aetosaur, placed outside of Stagonolepididae (the last common ancestor of Desmatosuchus and Aetosaurus). Interrelationships among the basal aetosaurs are not well understood but two clades with relatively apomorphic armour ? the spinose Desmatosuchinae and the generally wide-bodied Typothoracisinae ? are consistently recognized. Paramedian and lateral osteoderms are often distinctive at the generic level but variation within the carapace is not well understood in many taxa, warranting caution in assigning isolated osteoderms to specific taxa. The aetosaur skull and dentition varies across taxa, and there is increasing evidence that at least some aetosaurs relied on invertebrates and/or small vertebrates as a food source. Histological evidence indicates that, after an initial period of rapid growth, lines of arrested growth (LAGs) are common and later growth was relatively slow. The common and widespread Late Triassic ichnogenus Brachychirotherium probably represents the track of an aetosaur.

Recent studies on alginate blends, composites, and nanocomposites Lencina, María Malvina Soledad; Andreucetti, Noemi Amalia; Gomez, Cesar Gerardo; Villar, Marcelo Armando Alginate is the generic name given to the salts of alginic acids. Alginic acids are polysaccharides molecules which are built up of uronic acid residues, molecules with a carboxyl group on the carbon that is not part of the ring, Commercial alginates are currently obtained by extraction from brown seaweeds such as Laminaria digitata, Laminaria hyperborea, and Macrocystis pyrifera. However, several bacteria such as the nitrogen-fixing aerobe Azotobacter vinelandii and the opportunistic pathogen Pseudomonas aeruginosa also produce alginate. Alginates are unique in terms of their properties such as emulsifiers, thickeners, stabilizers, gelling and film forming, resultingin several applications for the food and pharmaceutical industries. Alginate has been regarded as an excellent polysachaccharide for gel systems because of its unique features such as biocompatibility, biodegradability, immnogenecity, and non-toxicity. In the biomedical area, alginates have been used as devices in several human health applications, such as excipients in drug delivery (DDS), wound dressings, as dental impression materials and in some formulations preventing gastric reflux, among others. Main characteristics and chemical modification, along with some interesting properties and applications are reviewed in this chapter.

Myths and Facts on cytosolic sucrose hydrolysis Vargas, Walter Alberto; Martin, Mariana Laura; Salerno, Graciela Lidia Sucrose plays an essential role in nature as part of the carbon dioxide assimilation pathway in the biosphere. Particularly, in plants occupies a unique position being essential for the allocation of carbon resources for growth and respiration, and participates in a regulatory network that coordinates metabolism and development. Its metabolism is strictly coordinated with photosynthesis-related genes by a feed-back regulation and a sugar signaling pathway. Also, sucrose accumulation has been shown to be involved in environmental stress responses and its degradation has been associated with a high demand of carbon and energy in sink tissues and anoxic environments. In the last decades, several studies on sucrose degradation in plant cells brought to light novel trails on carbon trafficking and the metabolic paths leading to regulation of gene expression and metabolic adjustment. However, recent findings point to an intricate relationship between sucrose metabolism and the whole plant physiology. This review is focused on the elusive Alkaline/Neutral-Invertase (A/N-Inv) isoforms, which have been long believed as cytosol-exclusive enzymes that hydrolyze the disaccharide for general or maintenance functions in the plant cell. Nevertheless, the story has changed in last few years when novel subcellular localizations and essential functions for a number of key physiological processes were demonstrated for A/N-Invs. From being minor proteins, scarcely mentioned in comprehensive descriptions of carbon flux in plants, these enzymes became leading actors in sucrose metabolism with significant roles in root morphogenesis, photosynthetic apparatus biosynthesis, and abiotic stress adaptation. The aim of this review article is to present a detailed and updated discussion of the most significant findings on the physiological properties of A/N-Invs. Also, we incorporate this group of invertases in the metabolic paths leading sucrose into the different circuits that govern carbon partitioning, storage and regulation of the molecular biology of the plant cell.

Cien Años de música argentina: Desde 1910 a nuestros días Pujol, Sergio Alejandro Cien años de música argentina es un mapa que contiene tanto los sitios "clásicos" como los "populares", indicando también las rutas que conectan unos con otros. Esta dicotomía tuvo una importancia decisiva en la historia cultural de Occidente, al menos hasta la década de los años 60.La Argentina, por las características de su historia social, ha sido un escenario privilegiado de permeabilidad entre escritura y oralidad musicales pero aun así las tensiones que atravesaron el mundo de la cultura a lo largo de la primera mitad del siglo XX reforzaron la polarización entre música clásica y música popular. Este libro da cuenta de esa polaridad, a la vez que se propone presentar un panorama integrado de la producción musical argentina entre 1910 y nuestros días.

Effect of entomopathogenic nematodes on the plant-parasitic nematode Nacobbus aberrans Caccia, Milena Guadalupe; Lax, Paola; Doucet, Marcelo Edmundo Nacobbus aberrans is a sedentary endoparasite nematode that forms galls in the roots of infected plants and produces important economic losses in some countries of the American continent. It has a wide host range, attacking mainly potato, tomato, sugar beet, and pepper crops. A reduction in the plant-parasitic nematode populations in the presence of entomopathogenic nematodes (EPNs) has been frequently reported. In the present work, the effect of the application of two native EPN isolates (Steinernema rarum and Heterorhabditis bacteriophora) on a N. aberrans population was evaluated in tomato plants under greenhouse conditions. Sixty days after inoculation, the number of galls and egg masses and the reproduction factor (RF) of N. aberrans were calculated. Of the variables analyzed, only the RF was significantly lower in both EPN treatments than in control. N. aberrans reproduction decreased by 57 and 53 % in plants inoculated with S. rarum and H. bacteriophora, respectively. These results showed that EPNs and their bacterial symbionts affected the reproductive potential of the N. aberrans population. This is the first study addressing the use of EPNs in the control of this important plant-parasitic nematode. © 2012 Springer-Verlag.

A novel method to produce a hierarchical porous carbon as a conductive support of PtRu particles. Effect on CO and Methanol electrooxidation Baena Moncada, Angelica Maria; Planes, Gabriel Angel; Moreno, Mario Sergio Jesus; Barbero, César Alfredo The fabrication and catalytic properties of hierarchical porous carbon loaded with PtRu particles was studied. A silica nanoparticles opal is filled with resorcinol/formaldehyde resin, which is then pyrolized to form a macroporous carbon. Depending on synthesis conditions the volume contraction induces mesopore formation in the macroporous carbon, creating a hierarchical porous carbon (HPC). The material consists of a thick, highly porous electrocatalytic film. PtRu nanoparticles were loaded inside the HPC by reduction of metallic ions with formic acid. The electrocatalytic activity toward CO and methanol oxidation was evaluated. The current densities for methanol electrooxidation at 60 °C (220 μA cm -2 and 120 Ag -1 at 0.55 V RHE) reveals high activity, suggesting that the catalysts consist of well disperse, small PtRu nanoparticles, with a low degree of agglomeration and good accessibility for reactants.

Computabilidad, complejidad computacional y verificación de programas Rosenfeld, Ricardo; Irazábal, Jerónimo Computabilidad, Complejidad Computacional y Verificación de Programas contiene lasquince clases que conforman la asignatura Teoría de la Computación y Verificación deProgramas, una introducción a la teoría de la computabilidad y complejidadcomputacional de problemas y la teoría de correctitud de programa. El libro es una suerte de segunda edición reducida deTeoría de la Computación y Verificación de Programas, de los mismos autores, editadoen 2010 por la EDULP conjuntamente con McGraw-Hill, el cual incluye además de lasclases de la asignatura básica, las de Teoría de la Computación y Verificación deProgramas Avanzada.El nuevo trabajo excluye principalmente la complejidad espacial, la verificaciónde los programas no determinísticos y concurrentes, el empleo de la lógica temporalpara verificar los programas reactivos, y la semántica denotacional de los lenguajes deprogramación, tópicos tratados en la obra anterior. De todos modos, en la presentepublicación hay secciones, breves, dedicadas a la jerarquía espacial, la terminación conhipótesis de fairnes de los programas no determinísticos, y la verificación de losprogramas concurrentes con memoria compartida, desarrolladas de la manera en quedichos temas son referenciados en la asignatura básica.

Prolactinomas: Role of VEGF, FGF-2 and CD31 Inés, María; Pérez Millán, M. I.; Cristina, Carolina; Berner, Silvia Ines; Becu, Damasia Pituitary tumors rarely produce metastasis, but cause considerable morbidity and mortality. Each pituitary tumor of clonal origin represents the multifactorial result of failure of different regulatory events where growth and angiogenic factors may play critical roles in hormone secretion and cell proliferation. Prolactinomas, pituitary tumors which secrete prolactin, are generally treated successfully with dopamine agonists, even though a 10–15 % are resistant to this pharmacological therapy. The role of angiogenesis in pituitary tumor development has been questioned, as pituitary tumors have been usually found to be less vascularized than the normal pituitary tissue. Nevertheless, a significantly higher degree of vasculature has been shown in invasive pituitary prolactinomas when compared to noninvasive prolactinomas. Furthermore, it has also been described that macroprolactinomas are more vascular than microprolactinomas. Many growth factors and their receptors are involved in pituitary tumor development. For example, VEGF, FGF-2, FGFR1 and PTTG, which give a particular vascular phenotype, are modified in pituitary adenomas. Inhibitors of angiogenesis, Thrombospondin-1 and FGF-2 endogenous antisense have also been detected. In particular, vascular endothelial growth factor (VEGF) the central mediator of angiogenesis in endocrine glands, was encountered in experimental and human pituitary tumors at different levels of expression, and in particular, in dopamine resistant prolactinomas. Even though the role of angiogenesis in pituitary adenomas is contentious, VEGF, making permeable pituitary endothelia, might contribute to adequate temporal vascular supply and mechanisms other than endothelial cell proliferation. The study of angiogenic factor expression in aggressive prolactinomas with resistance to dopamine agonists will yield important data in the search of therapeutical alternatives.

Bioactividad de beta-galactosidasa en un ambiente que simula la superpoblación molecular de los alimentos y del quimo. Ledesma, Darío; Perillo, Maria Angelica; Nolan, María Verónica El objetivo del presente trabajo fue investigar el efecto de la superpoblación macromolecular (SPM) sobre la cinética de hidrólisis de o-nitrofenil galactopiranósido (ONPG) catalizada por β -galactosidasa de E.coli (β -Gal). Para esto se aplicaron dos técnicas, espectroscopia UV-Visible (EF) y Calorimetría de titulación isotérmica (ITC), las cuales están basadas en principios físicos diferentes. La condición de SPM se simuló con disoluciones de polietilenglicol PM 6000 (PEG6000) a distintas concentraciones (0 a 35 % P/V). Los resultados arrojados por ambas técnicas (EF e ITC) no mostraron diferencias significativas, permitiéndonos: a) validar el uso del ITC para estudios cinéticos de reacciones catalizadas por enzimas en condiciones de SPM y b) aceptar que la SPM no interfirió sobre el comportamiento espectroscópico del producto de la reacción estudiada. El principal hallazgo fue que la velocidad de reacción (Vmax) no se vio afectada, mientras que la afinidad de la enzima por su sustrato (KM) sufrió una disminución significativa (KM aumentó de 0,14 a 1 mM para 0 y 35 % P/V PEG6000, respectivamente) a medida que aumentó la concentración del agente superpoblante. Esta disminución en la afinidad a altas concentración de PEG6000 podría deberse a la restricción difusional que impone la alta densidad molecular presente en estas condiciones. Este resultado es importante para el diseño de sistemas terapéuticos de sustitución enzimática.

Comunidad impropia: Estéticas posmodernas del lazo social Dipaola, Esteban Marcos En el libro se describe y analiza desde la literatura reciente en el campo, las transformaciones en el orden social, cultural y económico del capitalismo y sus incidencias en las formas de interacción social, tomando en cuenta los vínculos, la normatividad y como se producen actualmente las comunidades e identidades. Desde ese lugar, se entiende y piensa la posmodernidad y la globalización y las dimensiones desde las cuales comprender los efectos estéticos que sobre el lazo social producen las nuevas dinámicas de relaciones entre individuos.

Huellas de hierro: el ferrocarril uruguayo en imágenes Clavelli Garcia, Ximena; Fontana, Pablo Gabriel Desconocido por la mayoría de la población, el ferrocarril uruguayo atraviesa el territorio nacional transportando importantes volúmenes de carga que contribuyen al desarrollo de la economía regional mientras que habitantes del área metropolitana se trasladan cotidianamente en los trenes de pasajeros. A lo largo de este entramado ferroviario sobreviven estaciones que constituyen un invalorado patrimonio arquitectónico y social.Hemos recorrido esta red y las formaciones de AFE para retratar sus paisajes y los verdaderos microcosmos que constituyen las poblaciones que conecta, así como sus pasajeros y los trabajadores ferroviarios. Nuestra propuesta expone el registro en imágenes de la red ferroviaria, sus paisajes y protagonistas.Mediante un abordaje estético buscamos contribuir a la concepción del ferrocarril como medio de transporte indispensable por su función social, su valor cultural y patrimonial, su rol esencial para la conectividad y la descentralización, su aporte al cuidado ambiental, su contribución a la seguridad vial y su enorme potencial para el desarrollo productivo. Este proyecto tiene llegada a la población mediante una exposición itinerante de fotografías que recorrerá siete ciudades de nuestro país y la publicación del libro Huellas de Hierro que compila una parte importante del material relevado. Esta página web es el espacio donde estará concentrada y accesible la totalidad de la producción realizada.

Conflictividad escolar y modelos de autoridad: tensiones desde los años 60 Miguez, Daniel Pedro; Gallo, Andrea Paola En el transcurso de los últimos años la articulación entre el mundo familiar y la institución escolar ha sido objeto de renovado interés en el campo de los estudios sociales. En cierta medida, ello se debe a que tanto en el medio escolar como en el contexto familiar los vínculos intergeneracionales se han vuelto “problemáticos”…

Children's perception of parental relationship and personality traits in Argentinean children Mesurado, Maria Belen; Richaud, Maria Cristina The objectives of this chapter are: 1. To study differences, according to gender, in the perception of the maternal and paternal parenting styles (acceptance, pathological control and extreme autonomy); 2. To study differences in personality traits, according to gender (neuroticism, extraversion, openness to experience, agreeableness and conscientiousness); 3. To study the influence of parenting styles as perceived by children on their personality traits. The sample included 517 middle-class children aged 8?11 (M = 10.26, SD = .88) of both genders (253 boys and 264 girls), from primary schools in Argentina. The results indicate that maternal and paternal parenting are perceived in a different way by children, according to their gender. On the other hand, the results of this study revealed statistically significant differences in three of the ?Big Five? personality traits, with female children showing higher levels of agreeableness, conscientiousness and neuroticism than boys. Lastly, this study showed that when children perceive that their parents are accepting, they development positive traits (i.e., high levels of extraversion, openness to experience, agreeableness and conscientiousness) and avoid the development of negative traits (i.e. neuroticism) regardless of gender. We found that when parents exert pathological control over their children, meaning excessive control with low levels of displays of affection and acceptance, children develop higher levels of neuroticism which at the same time generating lower levels of openness to experience, agreeableness and conscientiousness. The results showed that extreme autonomy is associated with high levels of extraversion and low levels of openness to experience and agreeableness. However, no relationship was found to conscientiousness and neuroticism.

Higgs boson pair production at the LHC in the bbW+W- channel Papaefstathiou, Andreas; Yang, Li Lin; Zurita, Jose Francisco We consider Higgs boson pair production at the LHC in the b ¯bW+W− channel, with subsequent decay of the W+W− pair into `νjj. Employing jet substructure and event reconstruction techniques, we show that strong evidence for this channel can be found at the 14 TeV LHC with 600 fb−1 of integrated luminosity, thus improving the current reach for the production of Higgs boson pairs. This measurement will allow to probe the trilinear Higgs boson coupling λ.

Water stress and temperature effects on germination and early seedling growth of Digitaria eriantha Brevedan, Roberto; Busso, Carlos Alberto; Fioretti, Maria Nelida; Toribio, Mirta Susana; Baioni, Sandra Sonia; Torres, Yanina Alejandra; Fernandez, Osvaldo Alberto; Giorgetti, Hugo Dosindo; Bentivegna, Diego Javier; Entio, Lisandro Jose; Ithurrart, Leticia Soledad; Montenegro, Oscar Alberto; Mujica, Maria de la Merced; Rodriguez, Gustavo Dionisio; Tucat, Guillermo We assessed seed germination and seedling survival of the grass Digitaria eriantha cv. Irene to determine its potential for re-vegetation in the arid parts of Argentina. We evaluated the effects of (1) water stress and temperature on the germination, and (2) water stress on the early seedling growth under controlled conditions. During the first 24 hrs the germination at constant temperature exceeded by 50 % (one-way ANOVA: F3,20=67.40, p<0.001) the germination at the 30—10ºC alternating temperatures, although the total germination was about 80% in all temperature treatments. Germination percentages and coefficients of velocity were lower (two-way ANOVA main effect of water potential: Germination: 15 h, 18 h, 2006: F6,35=4.69, p<0.0013, 2007: F6,35=38.99, p<0.0001; 24 h, 2006: F6,35=10.66, p<0.0001, 2007: F=44.99, p<0.0001; 36 h, 2006: F6,35=6.05, p<0.0002, 2007: F6,35=23.54, p<0.0001; 60 h, F6,70= 2.46, p<0.0325; Coefficient of velocity: F6,70=30.33, p<0.0001) as water potentials decreased. Early seedling growth was lower (three-way-ANOVA main effect of water potential: F5,120=19.14, p<0.001) at lower water potentials. The high sensitivity of the two studied processes in D. eriantha suggests that it is quite susceptible to be considered for revegetation purposes in the rangelands of arid Argentina.

Effects of Microsite Conditions on Seedling Emergence at Grazed and Ungrazed Sites in Mountain Pampean Grasslands, Argentina Loydi, Alejandro; Peter, Guadalupe Seed germination and seedling establishment are the most critical period in many plant species. Plant diversity would be reflected according to the balance between seed bank composition and safe sites availability. In Pampean grasslands of Argentina, plant diversity is threatened by the advance of agriculture, being most of the original grasslands lost. In this context, is increasingly important to know the mechanisms involved in plant diversity maintainance. Seedling emergence would be partly responsible of plants diversity and it may be determined by microsites conditions (competition level, ground cover, presence of disturbances). Here we analyzed (1) the effect of above and below-ground competition and litter application on seedling emergence in non-grazed areas, and (2) the effect of cover of vegetation, litter or dung, bare ground, and soil removal on seedling emergence in grazed areas. In an exclosure and a grazed area, different microsites were created and natural seedling emergence was registered for two years. Above and below-ground competition reduced grasses emergence in non-grazed conditions, but did not affect forb emergence. Litter has no effect on emergence, although it reduced grasses survival. In the grazed areas, soil disturbance has a positive effect on emergence of seedling of all vegetation types, while litter application has a positive effect on grasses emergence. However, survival in this area was very low (<10%). Competition reduced seedling emergence, showing to be a major control factor for the regeneration of the dominant species in the non-grazed areas. Litter presence reduced survival of grasses, but not of forbs. In grazed areas, presence of litter improved microsites conditions, increasing grass emergence. While soil removal increased emergence of seedlings of all vegetation types, probably by favoring root development. In natural grasslands, availability of safe sites has an important role in the establishment of new individuals and regeneration.

Abiotic stress tolerance induced by endophytic PGPR Piccoli, Patricia Noemí; Bottini, Ambrosio Rubén Abiotic stresses, like shortage of water, soil salinity, and extreme temperatures, are a main treat over worldwide agricultural. Plant Growth Promoter Rhizobacteria (PGPR) refers to several endophytes with alleged positive effects on plant health and growth. Their use has been pursued mainly for agricultural applications to increase yields since three decades. And amongst such purported positive effects is the increase in plants? resistance to abiotic stresses, both by producing some phytohormones and by inhibiting the production of others. However, albeit the considerable amount of literature produce in the meantime the progress either in effective yield increases by inoculation with PGPR or in the understanding of the mechanisms involved in the purported beneficial effects has been rather scarce. This review focusses in revising the advancement made in the study of the different mechanisms involved in PGPR beneficial effects related to the diverse abiotic stresses, and in finding the reason why the limited success in practical application.