Bending Lipid Bilayers: A Closed-Form Collective Variable for Effective Free-Energy Landscapes in Quantitative Biology Masone, Diego Fernando; Uhart, Marina; Bustos, Diego Martin Curvature-related processes are of major importance during protein-membrane interactions. The illusive simplicity of membrane reshaping masks a complex molecular process crucial for a wide range of biological functions like fusion, endo- and exocytosis, cell division, cytokinesis, and autophagy. To date, no functional expression of a reaction coordinate capable of biasing molecular dynamics simulations to produce membrane curvature has been reported. This represents a major drawback given that the adequate identification of proper collective variables to enhance sampling is fundamental for restrained dynamics techniques. In this work, we present a closed-form equation of a collective variable that induces bending in lipid bilayers in a controlled manner, allowing for straightforward calculation of free energy landscapes of important curvature-related events, using standard methods such as umbrella sampling and metadynamics. As a direct application of the collective variable, we calculate the bending free energies of a ternary lipid bilayer in the presence and the absence of a Bin/Amphiphysin/Rvs domain with an N-terminal amphipathic helix (N-BAR), a well-known peripheral membrane protein that induces curvature.

CpxR-dependent thermoregulation of Serratia marcescens PrtA metalloprotease expression and its contribution to bacterial biofilm formation Bruna, Roberto Emanuel; Molino, María Victoria; Lazzaro, Martina; Mariscotti, Javier Fernando; Garcia Vescovi, Eleonora PrtA is the major secreted metalloprotease of Serratia marcescens. Previous reports implicate PrtA in the pathogenic capacity of this bacterium. PrtA is also clinically used as a potent analgesic and anti-inflammatory drug, and its catalytic properties attract industrial interest. Comparatively, there is scarce knowledge about the mechanisms that physiologically govern PrtA expression in Serratia. In this work, we demonstrate that PrtA production is derepressed when the bacterial growth temperature decreases from 37°C to 30°C. We show that this thermoregulation occurs at the transcriptional level. We determined that upstream of prtA, there is a conserved motif that is directly recognized by the CpxR transcriptional regulator. This feature is found along Serratia strains irrespective of their isolation source, suggesting an evolutionary conservation of CpxR-dependent regulation of PrtA expression. We found that in S. marcescens, the CpxAR system is more active at 37°C than at 30°C. In good agreement with these results, in a cpxR mutant background, prtA is derepressed at 37°C, while overexpression of the NlpE lipoprotein, a well-known CpxAR-inducing condition, inhibits PrtA expression, suggesting that the levels of the activated form of CpxR are increased at 37°C over those at 30°C. In addition, we establish that PrtA is involved in the ability of S. marcescens to develop biofilm. In accordance, CpxR influences the biofilm phenotype only when bacteria are grown at 37°C. In sum, our findings shed light on regulatory mechanisms that fine-tune PrtA expression and reveal a novel role for PrtA in the lifestyle of S. marcescens.

The monotypic Brazilian genus Diacrodon is a synonym of Borreria (Spermacoceae, Rubiaceae): Morphological and molecular evidences Miguel, Laila Mabel; Sobrado, Sandra Virginia; Janssens, Steven; Dessein, Steven; Cabral, Elsa Leonor Diacrodon is a monotypic genus of the tribe Spermacoceae (Rubiaceae), endemic to northeastern Brazil. Diacrodon compressus is frequently misidentified with a two lobed calyx species of Borreria, B. verticillata. Traditionally, in Spermacoceae the fruit type was considered a diagnostic character among the genera. In this sense, D. compressus presents a strongly compressed, one seeded and indehiscent fruit (vs. globose, two seeded and dehiscent fruit in B. verticillata). In this work, we address two objectives: evaluate the systematic position and determine the identity of Diacrodon in respect to other taxa. Molecular analyses using ITS and ETS indicate that D. compressus is strongly related to other species of Borreria. The morphological results revealed that D. compressus, despite of its type of fruit, is identical to Borreria in floral and palynological features. As conclusion, the new combination Borreria diacrodonta is made and a lectotype is designated. An updated description of the species and a key to the Borreria species with a two lobed calyx are provided. The distribution of B. diacrodonta is extended to Brazilian states Goiás and Minas Gerais, and Paraguay. By this taxonomical change it has become clear that the dehiscence of the fruits lack taxonomic value in the delimitation of Borreria.

Shifts in Zooplankton Behavior Caused by a Mixture of Pesticides Andrade, Victoria Soledad; Gutierrez, Marìa Florencia; Fantón, Noelia Isabel; Gagneten, Ana María Behavioral changes have been considered as appropriate to evaluate sublethal effects of pollutants. The aim of this study was to evaluate the effects of a mixture of pesticides, with glyphosate and 2,4-D (Gly + 2,4-D) as active ingredients, on the zooplankton evasion behavior from the fish Cnesterodon decemmaculatus. An increase in the evasion behavior was observed for copepods at two different concentrations of the Gly + 2,4-D mixture, for cladocerans at the lowest pesticide concentration, and for rotifers at the highest pesticide concentration. The response time to the fish signals also differed, being copepods faster than cladocerans and rotifers. All the exposed organisms showed higher variability in their distribution over time than those of controls (without pesticides). Our results suggest that the Gly + 2,4-D mixture formulations may have a mimetic effect with the fish alarm signals. The potential consequences of maladaptive responses triggered by pesticides, as well as the increased swimming activity, are discussed.

Signos de identidad femenina e identidad manuscrita medieval en las historias de reinas acusadas del Ms. Esc. h-I-13; Signs of female identity and medieval manuscript identity in the stories of accused queens of the Ms h-I-13 Zubillaga, Carina Alejandra El objetivo del presente trabajo es analizar los signos tanto físicos como verbales que asume la identidad femenina en las tres últimas historias de reinas acusadas del Ms. Esc. h-I-13, definiendo una heroicidad que es respuesta a la crisis del siglo XIV castellano, tanto identitaria como socio-cultural general, además de dar cuenta de las señales de la identidad manuscrita que caracterizan a esta singular antología medieval.; The objective of the present study is to analyze both physical and verbal signs that assumes the female identity in the three latest stories of accused queens of the MS h-I-13, defining a heroism which is response to the crisis of the 14th Century Castilian, both identity as socio-cultural general, in addition to account of the signals of the handwritten identity that characterize this unique medieval anthology.

Phosphatidyl-Inositol-3 kinase inhibitors regulate peptidoglycan-induced myeloid leukocyte recruitment, inflammation, and neurotoxicity in mouse brain Arroyo, Daniela Soledad; Gaviglio, Emilia Andrea; Peralta Ramos, Javier María; Bussi, Claudio; Avalos, Maria Paula; Cancela, Liliana Marina; Iribarren, Pablo Acute brain injury leads to the recruitment and activation of immune cells including resident microglia and infiltrating peripheral myeloid cells (MC), which contribute to the inflammatory response involved in neuronal damage. We previously reported that TLR2 stimulation by peptidoglycan (PGN) from Staphylococcus aureus, in vitro and in vivo, induced microglial cell activation followed by autophagy induction. In this report, we evaluated if phosphatidyl-inositol-3 kinase (PI3K) pharmacological inhibitors LY294200 and 3-methyladenine (3-MA) can modulate the innate immune response to PGN in the central nervous system. We found that injection of PGN into the mouse brain parenchyma (caudate putamen) triggered an inflammatory reaction, which involved activation of microglial cells, recruitment of infiltrating MC to injection site, production of pro-inflammatory mediators, and neuronal injury. In addition, we observed the accumulation of LC3B+ CD45+ cells and colocalization of LC3B and lysosomal-associated membrane protein 1 in brain cells. Besides, we found that pharmacological inhibitors of PI3K, including the classical autophagy inhibitor 3-MA, reduced the recruitment of MC, microglial cell activation, and neurotoxicity induced by brain PGN injection. Collectively, our results suggest that PI3K pathways and autophagic response may participate in the PGN-induced microglial activation and MC recruitment to the brain. Thus, inhibition of these pathways could be therapeutically targeted to control acute brain inflammatory conditions.

Formulation and assessment of Wash-Primer containing lanthanum tannate for steel temporary protection D'alessandro, Oriana; Selmi, Gonzalo Julian; Deya, Marta Cecilia; Di Sarli, Alejandro Ramón; Romagnoli, Roberto Tannins are polyphenols synthesized by plants and useful for the coating industry as corrosion inhibitors. In addition, lanthanum salts have a great inhibitory effect on steel corrosion. The aim of this study was to obtain lanthanum ‘‘tannate’’ with adequate solubility to be incorporated as the corrosion inhibitor in a wash-primer. The ‘‘tannate’’ was obtained from commercial ‘‘Quebracho’’ tannin and 0.1 M La(NO3)3. The soluble tannin was determined by the Folin–Denis reagent, while the concentration of Lanthanum was obtained by a gravimetric procedure. The protective action of ‘‘tannate’’ on SAE 1010 steel was evaluated by linear polarization curves and corrosion potential measurements. Lanthanum ‘‘tannate’’ was incorporated in a wash-primer formulation and tested by corrosion potential and ionic resistance measurements. The corrosion rate was also determined by the polarization resistance technique. Besides, the primer was incorporated in an alkyd paint system and its anticorrosion performance assessed in the salt spray cabinet and by electrochemical impedance spectroscopy. Results showed that lanthanum ‘‘tannate’’ primer inhibits the development of deleterious iron oxyhydroxides on the steel substrate and incorporated into a paint system had a similar behavior to the primer formulated with zinc tetroxychromate.

Age-related and photoperiodic variation of the DAZ gene family in the testis of the Syrian hamster (Mesocricetus auratus) González, Candela Rocío; Moverer, Luciana Mónica; Calandra, Ricardo Saul; Gonzalez de Calvar, Silvia Ines; Vitullo, Alfredo Daniel The Deleted in AZoospermia (DAZ) gene family regulates the development, maturation andmaintenance of germ cells and spermatogenesis in mammals. The DAZ family consists of two autosomalgenes, Boule and Dazl (Daz-like), and the Daz gene on chromosome Y. The aim of this study was toanalyze the localization of DAZL and BOULE during testicular ontogeny of the seasonal-breedingSyrian hamster, Mesocricetus auratus. We also evaluated the testicular expression of DAZ family genesunder short- or long-photoperiod conditions. In the pre-pubertal and adult testis, DAZL proteinwas found mainly in spermatogonia. BOULE was found in the spermatogonia from 20 days of ageand during the pre-pubertal and adult period it was also detected in spermatocytes and roundspermatids. DAZL and BOULE expression in spermatogonia was strictly nuclear only in 20-dayoldhamsters. We also detected the novel mRNA and protein expression of BOULE in Leydig cells.In adult hamsters, Dazl expression was increased in regressed testis compared with non-regressedtestis and DAZL protein expression was restricted to primary spermatocytes in regressed testis. Theseresults show that DAZL and BOULE are expressed in spermatogonia at early stages in the Syrianhamster, then both proteins translocate to the cytoplasm when meiosis starts. In the adult regressedtestis, the absence of DAZL in spermatogonia might be related to the decrease in germ cell number,suggesting that DAZ gene family expression is involved in changes in seminiferous epithelium during photoregression.

Aquaporins as targets of dietary bioactive phytocompounds Tesse, Angela; Grossini, Elena; Tamma, Grazia; Brenner, Catherine; Portincasa, Piero; Marinelli, Raul Alberto; Calamita, Giuseppe Plant-derived bioactive compounds have protective role for plants but may also modulate several physiological processes of plant consumers. In the last years, a wide spectrum of phytochemicals have been found to be beneficial to health interacting with molecular signaling pathways underlying critical functions such as cell growth and differentiation, apoptosis, autophagy, inflammation, redox balance, cell volume regulation, metabolic homeostasis, and energy balance. Hence, a large number of biologically active phytocompounds of foods have been isolated, characterized, and eventually modified representing a natural source of novel molecules to prevent, delay or cure several human diseases. Aquaporins (AQPs), a family of membrane channel proteins involved in many body functions, are emerging among the targets of bioactive phytochemicals in imparting their beneficial actions. Here, we provide a comprehensive review of this fast growing topic focusing especially on what it is known on the modulatory effects played by several edible plant and herbal compounds on AQPs, both in health and disease. Phytochemical modulation of AQP expression may provide new medical treatment options to improve the prognosis of several diseases.

El olvido del organismo: un análisis de las concepciones acerca de lo vivo y su valor en la biología actual; Forgetting the organism: an analysis of the conceptions about the living and its value in current biology Rendón, Constanza Alexandra; Klier, Gabriela Ruth En este trabajo indagamos los supuestos acerca de la naturaleza de lo vivo (centrándonos en su organización jerárquica) y del valor de lo vivo presentes en diferentes campos de estudio de la biología (biología molecular, genética, fisiología, biología evolutiva, embriología, ecología y biología de la conservación). La hipótesis que guió esta investigación es que las subdisciplinas biológicas centradas en los niveles inferiores de organización presentan una valoración de lo vivo diferente de aquella reconocida en áreas que abordan los niveles superiores de organización. A partir del análisis realizado hallamos una amplia valoración productiva de lo vivo en todas las áreas indagadas (además de la valoración de los organismos como herramientas para obtener conocimiento). En contraposición, encontramos que el valor intrínseco de lo vivo sólo es reconocido en algunos campos de estudio. Además los resultados obtenidos apoyan nuestra hipótesis relativa al vínculo entre los niveles de organización estudiados y la valoración de lo vivo: las subdisciplinas que otorgan prioridad a los niveles inferiores de organización no parecen considerar la valoración intrínseca de lo vivo, mientras que las áreas que abordan niveles de organización superiores tienden a reconocer ese tipo de valor. Finalmente presentamos algunas reflexiones acerca de la preeminencia del valor productivo de lo vivo en la bibliografía y de posibles conflictos valorativos al seno de la biología. Poner en cuestión los valores y supuestos que subyacen a las prácticas científicas resulta central en el contexto actual en el que las ciencias de la vida participan de diversas controversias éticas.; In this paper, we analyze the assumptions regarding the nature of the living -focusing on its hierarchical organization- and the value of the living in different fields of study of Biology (Molecular Biology, Genetics, Physiology, Evolutionary Biology, Embryology, Ecology and Conservation Biology). The hypothesis that guided this research is that biological sub-disciplines that focus on lower levels of organization confer a different value to the living than the areas that address higher levels of organization. We found that the productive value of organisms is widely acknowledged in all the subdisciplines (in addition to their value as tools for obtaining knowledge). In contrast, the intrinsic value of the living has only been recognized in a few fields of study. Besides, the obtained results support our hypothesis regarding a connection between the studied levels of organization and the value given to the living: the sub-disciplines that give priority to lower levels of organization do not seem to consider the intrinsic value of the living, while the areas that study higher levels of organization tend to recognize that type of value. Finally, we present some reflections about the prevalence of the productive value of the living in the bibliography and the possibility of value conflicts within biology. Questioning the values and assumptions that underlay scientific practices is crucial in the current context where life sciences participate in diverse ethical controversies.

NeQuick 2 and IRI Plas VTEC predictions for low latitude and South American sector Ezquer, Rodolfo Gerardo; Scida, Luis Alberto; Migoya Orue, Yenca Olivia; Nava, B.; Cabrera, Miguel Angel; Brunini, Claudio Antonio Using vertical total electron content (VTEC) measurements obtained from GPS satellite signals the capability of the NeQuick 2 and IRI Plas models to predict VTEC over the low latitude and South American sector is analyzed. In the present work both models were used to calculate VTEC up to the height of GPS satellites. Also, comparisons between the performance of IRI Plas and IRI 2007 have been done. The data correspond to June solstice and September equinox 1999 (high solar activity) and they were obtained at nine stations. The considered latitude range extends from 18.4°N to −64.7°N and the longitude ranges from 281.3°E to 295.9°E in the South American sector. The greatest discrepancies among model predictions and the measured VTEC are obtained at low latitudes stations placed in the equatorial anomaly region. Underestimations as strong as 40 TECU [1 TECU = 1016 m−2] can be observed at BOGT station for September equinox, when NeQuick2 model is used. The obtained results also show that: (a) for June solstice, in general the performance of IRI Plas for low latitude stations is better than that of NeQuick2 and, vice versa, for highest latitudes the performance of NeQuick2 is better than that of IRI Plas. For the stations TUCU and SANT both models have good performance; (b) for September equinox the performances of the models do not follow a clearly defined pattern as in the other season. However, it can be seen that for the region placed between the Northern peak and the valley of the equatorial anomaly, in general, the performance of IRI Plas is better than that of NeQuick2 for hours of maximum ionization. From TUCU to the South, the best TEC predictions are given by NeQuick2. The source of the observed deviations of the models has been explored in terms of CCIR foF2 determination in the available ionosonde stations in the region. Discrepancies can be also related to an unrealistic shape of the vertical electron density profile and or an erroneous prediction of the plasmaspheric contribution to the vertical total electron content. Moreover, the results of this study could be suggesting that in the case of NeQuick, the underestimation trend could be due to the lack of a proper plasmaspheric model in its topside representation. In contrast, the plasmaspheric model included in IRI, leads to clear overestimations of GPS derived TEC.

Comparison of the performance of latent heat flux products over southern hemisphere forest ecosystems: estimating latent heat flux error structure using in situ measurements and the triple collocation method Barraza Bernadas, Verónica Daniela; Grings, Francisco Matias; Restrepo-Coupe, Natalia; Huete, Alfredo Ramon In this study, we compared different remote-sensing (RS)-based land surface models (LSM) and reanalysis latent heat flux (LE) products over different forest ecosystems. We analysed the performance of three RS products, the MOD16A2, the Breathing Earth System Simulator (BESS) model, and a combined optical-microwave model (COM) in their ability to replicate eddy covariance (EC) flux observations of LE at eight southern hemisphere forest ecosystems and compared their results to simulated LE from the offline LSM (GLDAS/NOAH) and a reanalysis LE dataset (MERRA). To determine spatial uncertainties, we used the triple collocation (TC) method, which does not require a priori knowledge of the true LE value, at selected Australian EC locations and over an area without in situ measurement (the Dry Chaco Forest (DCF), Argentina). The spatial pattern of the TC results was commensurable with uncertainties calculated using EC observations, indicating that the TC method is a robust technique to estimate spatial uncertainties. As global products have been validated with EC measurement from Ozflux stations, we hypothesized and found, using the TC model, that LE products achieve a better performance over areas with EC from networks than over sites without ground-based measurements and may reflect over-calibration of models or a need for a more diverse representation of ecosystems at flux tower networks.

La doble contingencia como clave para una redefinición del concepto de orden social; The double contingency as a key to redefine the concept of social order Gonnet, Juan Pablo La doble contingencia constituye una dimensión conceptual clave en la teoría de los sistemas sociales de Niklas Luhmann al dar lugar a un novedoso tratamiento del problema del orden social. A partir de su consideración se hace posible explicar el orden social sin la necesidad de obturar la contingencia tanto de la acción individual como de las estructuras sociales. No obstante, algo que ha permanecido fuera de discusión es el concepto mismo de orden, que estaría involucrado en el planteo del autor. En principio, nos encontramos con una idea de orden bastante frecuente en la teoría social, que subordina el fenómeno a algún tipo de limitación (condicionamiento) de la acción/comunicación/selección (individual). El objetivo de este artículo es mostrar que la doble contingencia nos habilitaría también para una problematización y redefinición de esta concepción; The double contingency represents a key concept in Niklas Luhmann’s theory of social systems by giving rise to a new treatment of the problem of social order. From its consideration, it is possible to explain social order without blocking the contingency of both individual action and social structures. However, something that has remained out of discussion is precisely what concept of “order” is implied in the author’s proposal. In principle, we identify a frequently assumed conception of order in social theory, which is related to the limitation (or conditioning) of individual action/communication/selection. The aim of this paper is to demonstrate that the double contingency would also allow us to problematize and redefine this conception

Monoparametric family of metrics derived from classical Jensen–Shannon divergence Osán, Tristán Martín; Bussandri, Diego; Lamberti, Pedro Walter Jensen–Shannon divergence is a well known multi-purpose measure of dissimilarity between probability distributions. It has been proven that the square root of this quantity is a true metric in the sense that, in addition to the basic properties of a distance, it also satisfies the triangle inequality. In this work we extend this last result to prove that in fact it is possible to derive a monoparametric family of metrics from the classical Jensen–Shannon divergence. Motivated by our results, an application into the field of symbolic sequences segmentation is explored. Additionally, we analyze the possibility to extend this result into the quantum realm.

Cretaceous fossil gecko hand reveals a strikingly modern scansorial morphology: Qualitative and biometric analysis of an amber-preserved lizard hand Fontanarrosa, Gabriela; Daza Vaca, Juan Diego; Abdala, Virginia Sara Luz Gekkota (geckos and pygopodids) is a clade thought to have originated in the Early Cretaceous and that today exhibits one of the most remarkable scansorial capabilities among lizards. Little information is available regarding the origin of scansoriality, which subsequently became widespread and diverse in terms of ecomorphology in this clade. An undescribed amber fossil (MCZ R–190835) from mid-Cretaceous outcrops of the north of Myanmar dated at 99 Ma, previously assigned to stem Gekkota, preserves carpal, metacarpal and phalangeal bones, as well as supplementary climbing structures, such as adhesive pads and paraphalangeal elements. This fossil documents the presence of highly specialized adaptive structures. Here, we analyze in detail the manus of the putative stem Gekkota. We use morphological comparisons in the context of extant squamates, to produce a detailed descriptive analysis and a linear discriminant analysis (LDA) based on 32 skeletal variables of the manus. The comparative sample includes members of 15 extant squamate families (Agamidae, Dactyloidae, Iguanidae, Leiosauridae, Liolaemidae, Polychrotidae, Tropiduridae, Diplodactylidae, Eublepharidae, Gekkonidae, Phyllodactylidae, Sphaerodactylidae, Gymnophthalmidae, Teiidae, and Scincidae). Although the fossil manus is qualitatively more similar to that of members of Gekkota, the LDA analysis places it in a morphozone shared by Gekkota and Scincomorpha. This result is particularly interesting, given that despite the presence of paraphalangeal structures had only been reported in extant geckos of the families Gekkonidae and Phyllodactylidae, the usage of an adhesive subdigital system to climb originated independently in Gekkota, Scincidae, and Dactyloidae.

A review article about the deactivation of poly(o-aminophenol) film electrodes employing Impedance Spectroscopy and Surface Resistance Tucceri, Ismael Ricardo Objective: Storage time without use (STWU) in the supporting electrolyte solution for time periods beyond 30 hours deactivates poly(o-aminophenol) (POAP) films. Observations: Deactivated POAP films exhibit a lower conductivity than freshly prepared (nondeactivated) films Considering the interest in POAP synthesized in acid medium in both basic and applied research, not much attention has been paid to the decay of the electroactivity of POAP caused by its extensive use. Conclusion: Deactivation of poly(o-aminophenol) (POAP) film electrodes by STWU in the supporting electrolyte solution is reviewed in this work.

Optimal partition problems for the fractional Laplacian Ritorto, Antonella In this work, we prove an existence result for an optimal partition problem of the form min{Fs(A1, …, Am) : Ai ∈ As, Ai ∩ Aj = ∅ for i ≠ j}, where Fs is a cost functional with suitable assumptions of monotonicity and lower semicontinuity, As is the class of admissible domains and the condition Ai∩ Aj= ∅ is understood in the sense of Gagliardo s-capacity, where 0 < s < 1. Examples of this type of problem are related to fractional eigenvalues. As the main outcome of this article, we prove some type of convergence of the s-minimizers to the minimizer of the problem with s= 1 , studied in [5].

When small-sized and non-innovating firms meet a crisis: Evidence from the Italian labour market Perri, Stefano; Lampa, Roberto The Italian jobs crisis consists of a high percentage of non-working labour force, matched with a high percentage of discouraged, long-term unemployed and inactive population. Not only a sharp deregulation of the job market is groundless, but even a hypothetic return to expansionary fiscal policy would be insufficient in order to solve such structural problems. Starting from the literature dealing with the "Italian decline", this article demonstrates that the current problems of the Italian labour market are strictly connected to both (post-crisis) fiscal adjustment and pre-existing features of the industrial branch.

Spiders as potential bioindicators of mountain grasslands health: the Argentine tarantula Grammostola vachoni (Araneae, Theraphosidae) Schwerdt, Leonela Vanesa; de Villalobos, Ana Elena; Pérez Miles, Fernando Context. Bioindicators are used for conservation prioritization by means of spatial comparisons of a site value, or monitoring of ecosystem recovery or response to management. Spiders are characterized by their selection of quality habitats and guild responses to environmental change. However, they have only occasionally been used as bioindicators. Grammostola vachoni is an endemic tarantula that only occurs in the grasslands of the mountainous system in central Argentina and it is included in the Red List of the IUCN as Vulnerable.Aims. In this study, we performed a characterization of the microhabitat of G. vachoni at sites with different disturbance regimes and we analyzed the potential use of this species as a bioindicator of mountain grassland health.Methods. We determined the microhabitat characteristics around their refuges by mean of the soil parameters, as well as the composition and structure of vegetation and amount of refuge available.Key results. We found significant differences in the number of individuals and the percentage of occupation between sites. No significant differences were recorded in the soil characteristics and occupation of G. vachoni but we found that the composition of vegetation, and the heterogeneity and diversity of plants are influenced by different disturbance regimes, altering the distribution of spiders.Conclusions. Our results are consistent with those of other studies where the spiders have proved to be good bioindicators of different disturbances and we propose for the first time a Theraphosidae species for evaluating the state or health of a natural grassland.Implications. The information reported in this study is very important to provide data for a future re-categorization of G. vachoni for the Red List of IUCN. Also, we add new component of ecosystems for to use as indicator, open up the possibility for new research for the same and other species of a grasslands of the mountainous system.

Evaluación de la fijación biológica de nitrógeno y la producción de raíces en distintos cultivos de servicios y sus efectos sobre las reservas de C y N orgánico del suelo Pinto, Priscila Los cultivos de servicios pueden incluirse en las rotaciones agrícolas para proveer servicios ecosistémicos que se han perdido en los sistemas de agricultura continua. Estos cultivos, que se siembran en los periodos entre cultivos de renta y no se cosechan (i.e. cultivos de cobertura, abonos verdes, etc.), podrían ser sembrados en la Región Pampeana, con efectos positivos a corto y largo plazo sobre la producción de los cultivos de renta. En esta tesis, se caracterizaron especies de cultivos de servicios de gramíneas, leguminosas o crucíferas en cuanto a sus rasgos y efectos sobre el C y el N de la materia orgánica del suelo (MOS). Para ello se realizaron tres experimentos: (1) se evaluaron la biomasa aérea y subterránea y los aportes de N fijado biológicamente (NFB) en diez especies de leguminosas mediante el método de abundancia natural de 15N, durante dos años; (2) se evaluó el comportamiento de 8 especies de cultivos de servicios de gramíneas, leguminosas o crucíferas caracterizando su producción de biomasa aérea y subterránea, durante tres años; y (3) se evaluó el efecto acumulado de las rotaciones agrícolas con y sin cultivos de servicios sobre la formación y descomposición de la MOS, estimada mediante el uso de isótopos de 13C en la MOS particulada (POM) y la asociada a los minerales (MAOM). Los resultados de esta tesis sugieren que: a) los aportes de NFB de las leguminosas aumentan en función de la biomasa aérea, pero esta respuesta satura cuando la biomasa es muy alta debido a una dilución de la concentración de N; b) la producción de biomasa subterránea está determinada principalmente por la especie y se mantiene relativamente constante entre años en las gramíneas y las leguminosas, pero aumenta en función de la producción de biomasa aérea en las crucíferas; c) las disminuciones en la MAOM de los sistemas agrícolas se deben tanto al aumento de las pérdidas por descomposición como a la baja humificación de los aportes de biomasa en la MAOM, pero las disminuciones en la POM se deben principalmente a las pérdidas por descomposición, ya que la humificación no es sustancialmente afectada; d) las rotaciones que incluyen cultivos de servicios de gramíneas aumentan la descomposición de la MAOM pero luego forman MAOM nueva sugiriendo un aumento en la velocidad de ciclado del C y e) las leguminosas, en cambio, no estimulan la descomposición del MAOM pero si la descomposición de la POM y presentan altas tasas de humificación de sus residuos en la MAOM, logrando una alta formación de MAOM. La variabilidad observada en los rasgos que presentan las distintas especies y su impacto en la formación de MOS, resalta la importancia de seleccionar y evaluar a los cultivos de servicios considerando aquellos rasgos que se encuentren relacionados con los servicios ecosistémicos que se quieren mejorar.; Service crops can be included in agricultural rotations to provide ecosystem services that have been lost in continuous agricultural systems. These crops, which are sown in between cash crops periods and are not harvested (i.e. cover crops, green manure, etc.), could be sown in the Pampean Region with positive short and long-term effects on the cash crops yields. In this thesis, service crops candidates (certain grasses, legumes, and crucifers species) were characterized in terms of their traits and effects on the C and N of soil organic matter (MOS). To achieve this goal, three experiments were carried out: (1) shoot and root biomass and the N biologically fixed contributions (NFB) in ten legume species were evaluated for two years using the 15N natural abundance method; (2) shoot and root biomass were evaluated in 8 genotypes of grasses, legumes or cruciferous crops for three years; and (3) the cumulative effect of agricultural rotations, with and without service crops, on the MOS formation and decomposition was estimated through 13C isotopes in the particulate (POM) and in the associated with minerals (MAOM) fractions after three years. Results suggest that: a) legumes NFB contributions increase with shoot biomass, but this response saturates at high biomass values due to N concentration dilution in the tissues; b) root biomass is determined mainly by the genotype (i.e. different species) and by shoot biomass in crucifers, but for grasses and legumes root biomass remains relatively despite changes in shoot biomass; c) MAOM decreases in agricultural systems are due both to high decomposition losses and low humification in the MAOM, while POM decreases are only explained by high decomposition losses since the humification is not substantially affected; d) agricultural rotations with service crops of grasses increase the MAOM decomposition but at the same time generate new MAOM, suggesting an increase in the C turn-over; and e) legumes stimulate the POM decomposition, but not MAOM decomposition, and promote MAOM formation through their high humification rates. The variability observed in different species traits and their impact on the MOS formation highlights the importance of evaluating and selecting traits in service crops to improve the targeted ecosystem services.