Usos sociales del agua y medio ambiente en la cuenca internacional del río Colorado

en este artículo se analiza cómo se relaciona la trasfor-mación de los usos sociales del agua con los cambios en lasformas de establecer el vínculo hombre-naturaleza. Se hanmodificado los conceptos y las ideas sobre qué debe hacersecon los recursos naturales, por lo que la forma de aprove-charlos, discutir y hacer propuestas sobre ellos cambia, alenfrentarse a los problemas de manera diferente. Esto seilustra con la corriente internacional del río Colorado, quecon frecuencia se ve como uno de los cuerpos de agua quemayores conflictos ha generado en el sigloxxy que, paraalgunos, puede ser uno de los puntos más importantes deestrés hídrico en los años siguientes

Existence of positive solution of a nonlocal logistic population model

In this paper, we study the existence of positive solutions for a class of nonlocal problem arising in population dynamic. Basically, we prove our results via bifurcation theory.Conselho Nacional de Desenvolvimento Científico e Tecnológico (Brasil)Ministerio de Economía y CompetitividadCoordenação de Aperfeiçoamento de Pessoal de Nivel Superior (Brasil

Genes for asparagine metabolism in Lotus japonicus : differential expression and interconnection with photorespiration

Background: Asparagine is a very important nitrogen transport and storage compound in plants due to its high nitrogen/carbon ratio and stability. Asparagine intracellu lar concentration depends on a balance between asparagine biosynthesis and degradation. The main enzymes involved in asparagine metabolism are as paragine synthetase (ASN), asparaginase (NSE) and serine-glyoxylate aminotransfera se (SGAT). The study of the genes encoding for these enzymes in the model legume Lotus japonicus is of particular interest since it has been proposed that asparagine is the principal molecule used to transport reduced nitrogen within the plant in most temperate legumes. Results: A differential expression of genes encoding for seve ral enzymes involved in asparagine metabolism was detected in L. japonicus . ASN is encoded by three genes, LjASN1 was the most highly expressed in mature leaves while LjASN2 expression was negligible and LjASN3 showed a low expression in this organ, suggesting that LjASN1 is the main gene responsible for asparagine synthesis in mature leaves. In young leaves, LjASN3 was the only ASN gene expressed although at low levels, while all the three genes encoding for NSE were highly expressed, especially LjNSE1 .Innodules, LjASN2 and LjNSE2 were the most highly expressed genes, suggesting an important role for these genes in this organ. Several lines of evidence support the connection between asparagine metabolic genes and photorespiration in L. japonicus : a) a mutant plant deficient in LjNSE1 showed a dramatic decrease in the expression of the two genes encoding for SGAT; b) expression of the genes involved in asparagine metabolism is altered in a photorespiratory mutant lacking plastidic glutamine synthetase; c) a clustering analysis indicated a similar pattern of expression among several genes involved in photorespiratory and asparagine metabolism, indicating a clear link between LjASN1 and LjSGAT genes and photorespiration. Conclusions: The results obtained in this paper indicate the exis tence of a differential expression of asparagine metabolic genes in L. japonicus and point out the crucial relevance of particular genes in different organs. Moreover, the data presented establish clear links betw een asparagine and photorespiratory metabolic genes in this plant.Junta de Andalucía (P10-CVI- 6368)FEDER-Ministerio de Economía y Competitividad (AGL 2014 – 54413-R

Reassimilation of photorespiratory ammonium in Lotus japonicus plants deficient in plastidic glutamine synthetase

It is well established that the plastidic isoform of glutamine synthetase (GS2) is the enzyme in charge of photorespiratory ammonium reassimilation in plants. The metabolic events associated to photorespiratory NH4+ accumulation were analyzed in a Lotus japonicus photorespiratory mutant lacking GS2. The mutant plants accumulated high levels of NH4+when photorespiration was active, followed by a sudden drop in the levels of this compound. In this paper it was examined the possible existence of enzymatic pathways alternative to GS2 that could account for this decline in the photorespiratory ammonium. Induction of genes encoding for cytosolic glutamine synthetase (GS1), glutamate dehydrogenase (GDH) and asparagine synthetase (ASN) was observed in the mutant in correspondence with the diminishment of NH4+. Measurements of gene expression, polypeptide levels, enzyme activity and metabolite levels were carried out in leaf samples from WT and mutant plants after different periods of time under active photorespiratory conditions. In the case of asparagine synthetase it was not possible to determine enzyme activity and polypeptide content; however, an increased asparagine content in parallel with the induction of ASN gene expression was detected in the mutant plants. This increase in asparagine levels took place concomitantly with an increase in glutamine due to the induction of cytosolic GS1 in the mutant, thus revealing a major role of cytosolic GS1 in the reassimilation and detoxification of photorespiratory NH4+ when the plastidic GS2 isoform is lacking. Moreover, a diminishment in glutamate levels was observed, that may be explained by the induction of NAD (H)-dependent GDH activityJunta de Andalucía P1OCVI- 6368 y BIO-163Ministerio de Economía y Competitividad AGL2014-54413-

Hydrogeochemical characteristics of a volcanic-sedimentary aquifer with special emphasis on Fe and Mn content: A case study in Mexico

Previous studies performed on the volcanic-sedimentary aquifer of the Tenancingo Valley (Mexico) reports high concentrations of Fe, Mn, and NO3 −, and water from several wells receives purification treatments due to presence of Fe and Mn. These studies have not achieved conclusive results regarding the origin of Fe and Mn, nor have hydrogeochemical evaluations of the aquifer been performed. The present study aimed to evaluate the physicochemical characteristics of the water and identify the geochemical processes that determine presence of Fe and Mn in groundwater. This characterization was based on physicochemical data from well and spring samples (16 samples) during dry and rainy seasons (June and November 2012, respectively). The EC, temperature and pH ranged from 125 to 793 μS cm−1 , 14.5 to 24.9 °C and 6.5 to 8.5 pH units, respectively. The Eh values ranged from −219 to 327 mV, indicating the existence of both reducing and oxidizing zones. Presence of Fe and Mn was detected in both springs and wells; concentrations were higher in well, exceeding 4 mg Fe L−1 and 0.5 mg Mn L−1 . Content of Si ranged from 12 to 47 mg L−1 . A model of the hydrogeochemical behavior of the aquifer was created to highlight the following: i) processes involved in water-rock interactions, including fluctuations in silicate levels that determine anionic and cationic content of water, and ii) redox reactions as the major control processes of Fe and Mn. Water quality for human use is restricted by Fe and Mn content and pH. For irrigation use, significant limitations were not presente

Cellular Stress Following Water Deprivation in the Model Legume Lotus japonicus

Drought stress is one of the most important factors in the limitation of plant productivity worldwide. In order to cope with water deprivation, plants have adopted several strategies that produce major changes in gene expression. In this paper, the response to drought stress in the model legume Lotus japonicus was studied using a transcriptomic approach. Drought induced an extensive reprogramming of the transcriptome as related to various aspects of cellular metabolism, including genes involved in photosynthesis, amino acid metabolism and cell wall metabolism, among others. A particular focus was made on the genes involved in the cellular stress response. Key genes involved in the control of the cell cycle, antioxidant defense and stress signaling, were modulated as a consequence of water deprivation. Genes belonging to different families of transcription factors were also highly responsive to stress. Several of them were homologies to known stress-responsive genes from the model plant Arabidopsis thaliana, while some novel transcription factors were peculiar to the L. japonicus drought stress response

Evaluation of single root canals filled using the lateral compaction, tagger's hybrid, microseal and guttaflow techniques

The aim of this study was to determine the percentage of voids, gutta-percha and root canal sealer using 4 different filling techniques. Fifty-two extracted maxillary lateral incisors were prepared using the crown-down pressureless technique. The teeth were randomly divided in 4 groups (n=13): Lateral compaction (LC), Tagger's hybrid (TH), MicroSeal (MS) and GuttaFlow (GF) techniques. Horizontal cross-sections were made at the 2, 10 and 15 mm levels from the apex. Digital images of the root canal areas were acquired using a stereomicroscope and examined using the Image Tool 3.0 software. Statistical analysis was performed using the Kruskal-Wallis test (&#945;=0.05). In general, a significant decrease in the gutta-percha filled area and increase of sealer area were observed at the apical level for all the evaluated techniques (p<0.05). With regard to the presence of voids, no significant difference was found. MS and TH techniques showed a larger gutta-percha filled area than LC and GF techniques at the coronal and middle third level (p<0.05). From the results of the present study, it may be concluded that the gutta-percha filled area of fillings decrease at the apical level, regardless of the filling technique used.O objetivo do estudo foi determinar a porcentagem de espaços vazios, guta-percha e cimento após a obturação por 4 diferentes técnicas. Cinquenta e dois incisivos laterais superiores humanos extraídos foram instrumentados pela técnica coroa-ápice sem pressão. Os dentes foram randomicamente divididos em 4 grupos (n=13): Condensação lateral (LC), Técnica híbrida de Tagger (TH), MicroSeal (MS) e GuttaFlow (GF). Foram feitas secções horizontais a 2, 10 e 15 mm do ápice. Imagens digitais foram obtidas dos canais por meio de estereomicroscópio e analisadas no programa Image Tool 3.0. A análise estatística foi feita utilizando o teste de Kruskal-Wallis (&#945;=0,05). Em geral foi observado um significante decréscimo na área de guta-percha e um aumento na área de cimento para todas as técnicas analisadas (p<0,05). Com relação à presença de espaços vazios, não houve diferença estatística entre as técnicas (p&gt;0,05). As técnicas MS e TH apresentaram área de guta-percha maior que as técnicas LC e GF nos terços médio e cervical (p<0,05). Após análise dos resultados foi possível concluir que a área de guta-percha nas obturações diminui em sentido apical, independente da técnica utilizada

La “Ruta de las huellas fósiles” (Monsagro, Salamanca): un ejemplo de iniciativa geoturística aplicada al desarrollo rural

Se presenta la “Ruta de las huellas fósiles”, realizada en el casco urbano de Monsagro (Sierra de Francia, Salamanca). Mediante seis paneles didácticos e interpretativos, que incluyen el acceso “online” desde las nuevas tecnologías (smartphone, tablets, ipod….) a información complementaria implementada en videos, códigos QR, geoapps y juegos, se han promocionado y divulgado los contenidos geológicos de la zona, basados principalmente en el interés paleontológico de sus icnofósiles, atribuidos a diversos tipos de gusanos y trilobites durante el Ordovícico Inferior, y en el interés geomorfológico de sus cresterías cuarcíticas con relieve apalachiense, del encajamiento fluvial del río Agadón y de sus formaciones superficiales como canchales. Los visitantes señalan como fortalezas de la ruta su fácil y didáctico recorrido, así como la implicación ciudadana en la conservación de las icnitas

The Diboson Excess: Experimental Situation and Classification of Explanations; A Les Houches Pre-Proceeding

We examine the `diboson' excess at $\sim 2$ TeV seen by the LHC experiments in various channels. We provide a comparison of the excess significances as a function of the mass of the tentative resonance and give the signal cross sections needed to explain the excesses. We also present a survey of available theoretical explanations of the resonance, classified in three main approaches. Beyond that, we discuss methods to verify the anomaly, determining the major properties of the various surpluses and exploring how different models can be discriminated. Finally, we give a tabular summary of the numerous explanations, presenting their main phenomenological features.Comment: 37 pages, 9 Figures, 1 Tabl

Use of transcriptomics and co-expression networks to analyze the interconnections between nitrogen assimilation and photorespiratory metabolism

Nitrogen is one of the most important nutrients for plants and, in natural soils, its availability is often a major limiting factor for plant growth. Here we examine the effect of different forms of nitrogen nutrition and of photorespiration on gene expression in the model legume Lotus japonicus with the aim of identifying regulatory candidate genes co-ordinating primary nitrogen assimilation and photorespiration. The transcriptomic changes produced by the use of different nitrogen sources in leaves of L. japonicus plants combined with the transcriptomic changes produced in the same tissue by different photorespiratory conditions were examined. The results obtained provide novel information on the possible role of plastidic glutamine synthetase in the response to different nitrogen sources and in the C/N balance of L. japonicus plants. The use of gene co-expression networks establishes a clear relationship between photorespiration and primary nitrogen assimilation and identifies possible transcription factors connected to the genes of both routes.España. Ministerio de Economía y Competitividad AGL2014-54413-REspaña Junta de Andalucia, Consejería de Economía, Innovación y Ciencia BIO-163España Junta de Andalucia, Consejería de Economía, Innovación y Ciencia P10-CVI-636