Determinació d'Al, Fe, Mg, Ti i Mn en sediments marins. Estudi comparatiu de les tècniques de plasma d'inducció (ICP), d'absorció atòmica (AAS) i d'espectrografia d'emissió (OES)

S'ha realitzat un estudi comparatiu de les tècniques d'ICP, AAS i OES analitzant Al, Fe, Mg, Ti i Mn en silicats (sediments marins). Per als elements Al, Mg i Ti, la tècnica d'ICP és millor que la d'ASS. Les interferències interelementals en AAS queden eliminades en gran part en treballar amb una matriu fluorobòrica, però l'ajust de les condicions de treball és crític. Hom analitza, fent servir condicions de compromís, una sèrie de mostres —de sediments marins i s'observa que els resultats d'AAS per a aquests elements són més baixos que els d'ICP i OES amb un 99% de confiança. La precisió de l'anàlisi amb ICP i AAS és de l'ordre del 3% i amb OES d'un 9%. Per a l'anàlisi de traces en silicats, quan el nombre de mostres és elevat, la tècnica d'OES es la més aconsellable.A comparative study of ICP, AAS and OES techniques in order to determinate Al, Ee, Mg, Ti and Mn in silicates (marine sediments) is carried out. ICP has shown to be better than AAS for Al, Mg and Ti determinations. Working with a fluoboric matrix the AAS chemical interferences are almost removed, but instrumental conditions are very critical. For these elements, under compromise conditions, the AAS results are lower than the ICP ones with a 99% confidence interval. The analytical precision is approximately 3% for ICP and AAS and 9% for OES. When trace elements must be analysed in a large number of silicate samples the OES technique is the most suitable

3D mapping of the SPRY2 domain of ryanodine receptor 1 by single-particle Cryo-EM

The type 1 skeletal muscle ryanodine receptor (RyR1) is principally responsible for Ca(2+) release from the sarcoplasmic reticulum and for the subsequent muscle contraction. The RyR1 contains three SPRY domains. SPRY domains are generally known to mediate protein-protein interactions, however the location of the three SPRY domains in the 3D structure of the RyR1 is not known. Combining immunolabeling and single-particle cryo-electron microscopy we have mapped the SPRY2 domain (S1085-V1208) in the 3D structure of RyR1 using three different antibodies against the SPRY2 domain. Two obstacles for the image processing procedure; limited amount of data and signal dilution introduced by the multiple orientations of the antibody bound in the tetrameric RyR1, were overcome by modifying the 3D reconstruction scheme. This approach enabled us to ascertain that the three antibodies bind to the same region, to obtain a 3D reconstruction of RyR1 with the antibody bound, and to map SPRY2 to the periphery of the cytoplasmic domain of RyR1. We report here the first 3D localization of a SPRY2 domain in any known RyR isoform.The authors want to thank the Brigham and Women’s Hospital Biomedical Research Institute (to MS), the Australian National Health and the Medical Research Council (471418 to AD, MC and PB), and the European Commission (Marie Curie Action PIOF-GA-2009-237120 to AP-M)

La vegetación de zonas erosionadas en la depresión media del Ebro y en el Prepirineo: influencia de factores climáticos, topográficos y geomorfológicos en la composición florística de las comunidades vegetales

[Resumen] Se han analizado 732 inventarios de vegetación en zonas sometidas a procesos erosivo-sedimentarios de un área del NE de la Península Ibérica, muy diversa climática y litológicamente (yesos, arcillas, margas y flysch). El objetivo del estudio es determinar cómo afectan dichos procesos a la composición florística de las comunidades vegetales de los diferentes sustratos. El tipo de sustrato ejerció una gran influencia sobre los procesos estudiados, siendo la cobertura de las fanerógamas el parámetro que mejor se asoció con el grado de erosión. En las zonas más secas con bajas tasas de erosión (yesos), las características topográficas controlaron la distribución de las comunidades vegetales, mientras que en las zonas más húmedas, sometidas a procesos erosivos más dinámicos (margas), la composición florística fué más homogénea y menos dependiente de la topografía y del grado de erosión. Los procesos erosivosedimentarios explicaron mejor la composición florística cuanto menor era la escala espacial de análisis.[Abstract] We have analysed 732 releves of plant communities taken from eroded lands in the NE Iberian Peninsula. This diverse area has very different climates and substrata: gypsum, clays, marls and flysch. The aim of the study was to explore how erosion and sedimentation processes affect floristic composition of plant communities in such different substrata. Substratum had a high influence on the studied processes, the cover of fanerogams being the best correlated parameter with erosion grade. In the driest lands, with low erosion rates (gypsum), plant community distribution was mostly affected by topography, but in the wettest areas, with strong and more dynamic erosional processes (marls), the floristic composition was more homogeneus and depended less on the topography and the erosion grade. The erosionsedimentation processes better explained the floristic composition when the scale of analysis was reduced

Is leishmaniasis endemic on the island of Minorca (Spain)?. A human visceral case after living 13 years in Minorca

Ecoepidemiologica studies performed in Minorca (Balearic Islands) seem to show that leishmaniasis is not endemic in this island, even in the presence of the vector. All cases of leishmaniasis in man or dog diagnosed in the island seem to come from other Spanish regions. A recent case of human visceral leishmaniasis in a man who had not left Minorca for 13 years calls into question this assumption or the time that Leishmania may persist asymptomatic in the host

Rapid extracellular acidification induced by glucose metabolism in non-proliferating cells of Serratia marcescens

The addition of glucose or other sugars to resting cells of Serratia marcescens induced rapid acidification of the extracellular medium. This acidification was due to the catabolism of sugars. The rate of acidification depended on the carbon source and its concentration. HPLC analysis of the supernatants demonstrated that the progressive fall in pH resulted from the rapid production of lactic, acetic, pyruvic and citric acids. Other microorganisms were tested for their ability to produce this rapid acidification of the medium. This study may provide a rapid and simple method for metabolism studies

Differential nitrogen cycling in semiarid sub-shrubs with contrasting leaf habit

Nitrogen (N) is, after water, the most limiting resource in semiarid ecosystems. However, knowledge on the N cycling ability of semiarid woody plants is still very rudimentary. This study analyzed the seasonal change in the N concentrations and pools of the leaves and woody organs of two species of semiarid sub-shrubs with contrasting leaf habit. The ability of both species to uptake, remobilize and recycle N, plus the main storage organ for N during summer drought were evaluated. We combined an observational approach in the field with experimental 15N labelling of adult individuals grown in sand culture. Seasonal patterns of N concentrations were different between species and organs and foliar N concentrations of the summer deciduous Lepidium subulatum were almost double those of the evergreen Linum suffruticosum. L. subulatum up took ca. 60% more external N than the evergreen and it also had a higher N resorption efficiency and proficiency. Contrastingly, L. suffruticosum relied more on internal N remobilization for shoot growth. Differently to temperate species, the evergreen stored N preferentially in the main stem and old trunks, while the summer deciduous stored it in the foliage and young stems. The higher ability of L. subulatum to uptake external N can be related to its ability to perform opportunistic growth and exploit the sporadic pulses of N typical of semiarid ecosystems. Such ability may also explain its high foliar N concentrations and its preferential storage of N in leaves and young stems. Finally, L. suffruticosum had a lower ability to recycle N during leaf senescence. These strategies contrast with those of evergreen and deciduous species from temperate and boreal areas, highlighting the need of further studies on semiarid and arid plants

Modelo de gestión de ciencia abierta para la Universidad Autónoma de Zacatecas: hacia la formación de investigadores en prácticas abiertas

El presente trabajo expone el modelo de gestión implementado para garantizar el trabajo continuo, alimentación y mejoras de un Repositorio Institucional (RI) en una universidad mexicana, la Universidad Autónoma de Zacatecas (UAZ), lo que derivó en la necesidad de capacitar al colectivo de investigadores sobre las diferentes propuestas de la Ciencia Abierta y las formas de trabajo sugeridas bajo este paradigma, buscando formar a los científicos de la universidad para realizar producción científica y publicaciones de calidad que permitieran el uso del RI de forma sostenida y que culminó con la apertura de la Oficina de Ciencia Abierta. La metodología empleada es un análisis comparativo y exposicional del desarrollo del modelo de trabajo en primera instancia del repositorio y en un segundo tiempo de la Oficina de Ciencia Abierta, creada con el objetivo de ofrecer apoyo integral a los investigadores de la institución, finalizando con la prospectiva de trabajo, así como con la presentación de logros bajo este modelo de acción institucional.Ibero-American Science and Technology Education Consortiu