Relationships between diatoms and the environment in Spanish reservoirs

Diatoms are very useful environmental indicators in limnological and paleolimnological studies. Spanish reservoirs offer a valuable opportunity for the study of relationships between diatoms and environmental conditions, since these ecosystems are abundant in this country and the patterns of their regional limnology are well established. We report the results from a study carried out on diatom communities in 40 reservoirs from several Spanish water basins. More than 200 diatom taxa were found. A canonical correspondence analysis was applied to the abundance data of the most common taxa and the main physical and chemical variables. This analysis showed that mineralisation (conductivity and alkalinity) was the most important environmental factor explaining diatom distribution, while trophic state was the second most important. These results are similar to those in previous studies on phytoplankton in Spanish reservoirs. Conductivity and alkalinity optima of the selected taxa allow us to consider these taxa as good indicators of water mineral content in similar ecosystems.Las diatomeas son indicadores ambientales muy útiles en estudios limnológicos y paleolimnológicos. En España los embalses ofrecen una gran oportunidad para el estudio de las relaciones entre las diatomeas y las condiciones ambientales, ya que son ecosistemas muy abundantes y las principales características de su limnología regional están bien estudiadas. Se presentan aquí los resultados de un estudio sobre las comunidades de diatomeas efectuado en 40 embalses de diversas cuencas hidrográficas españolas. En ellos se encontraron más de 200 taxones de diatomeas. Se efectuó un análisis de correspondencias canónicas con los datos de abundancia de los taxones más frecuentes y las principales variables físico-químicas. Este análisis muestra que el factor con mayor influencia sobre las comunidades de diatomeas es la mineralización (conductividad y alcalinidad), y en segundo lugar el grado trófico. Estos resultados son similares a estudios previos sobre el fitoplancton de embalses españoles. Los valores de los óptimos respecto a la conductividad y alcalinidad de los principales taxones, permiten considerar dichos taxones como buenos indicadores del contenido mineral del agua en ecosistemas similares

Cyanobacteria distribution and abundance in the Spanish water reservoirs during thermal stratification

A study of the distribution and abundance of Cyanobacteria in 47 Spanish water reservoirs revealed a significant correlation between these algae and total phosphorus in the water. Cyanobacteria distribution was related to the N:P ratio, and they were scarce when the atomic ratio of total inorganic N / total P exceeded 50. The N:P ratio was influenced by the geology of the catchment, and it was lower in the solute-poor waters of western Iberian Peninsula, where Cyanobacteria were more abundant (mainly the Nostocales). Therefore, this area would be more prone to present problems derived from Cyanobacteria proliferation than the eastern part of Spain. In the studied reservoirs we have recorded 45 taxa of Cyanobacteria, many of which can produce toxins. A comparison of our results with those of previous studies served to conclude that Cyanobacteria have increased both in biomass and species number in Spanish reservoirs.El estudio de la distribución y abundancia de Cianobacterias en 47 embalses españoles reveló una correlación significativa entre estas algas y la concentración de fósforo total en el agua. La distribución de Cianobacterias estuvo relacionada con el cociente N:P, siendo generalmente poco abundantes cuando la relación atómica N inorgánico total / P total fue superior a 50. La relación N:P en el agua está influenciada por la geología de la cuenca, y fue menor en las aguas menos mineralizadas del oeste de la Península Ibérica, donde las cianobacterias fueron más abundantes (especialmente las nostocales). Por lo tanto, esta zona de la península Ibérica sería más propensa a sufrir problemas relacionados con la proliferación de Cianobacterias que la zona este de España. En los embalses estudiados hemos encontrado 45 taxones de Cianobacterias, muchas de las cuales pueden producir toxinas. La comparación de nuestros resultados con estudios realizados previamente sirvió para concluir que en los embalses españoles se ha producido un aumento del número de especies y de la biomasa de Cianobacterias

Synchrotron radiation photoionization mass spectrometry of laser ablated species

The present paper describes an experimental apparatus suitable to create and study free clusters by combining laser ablation and synchrotron radiation. First tests on sulfur samples, S, showed the production, through laser ablation, of neutral Sn clusters (n = 1–8). These clusters were ionized using synchrotron radiation at photon energies from 160 eV to 175 eV, across the S 2p core edge. The feasibility of such combined ablation–synchrotron radiation experiments is demonstrated, opening new possibilities on the investigation of free clusters and radical

A Comparison Of 3,4,6A,7,10,10A-Hexahydro-7,10-Epoxypyrimido 2,1-A Isoindol-6(2H)-One And 2-(2-Aminoethyl)-3A,4,7,7A-Tetrahydro-1H-4,7-Epoxyisoindole-1,3(2H)-Dion E: Structural And Reactivity Differences Of Two Homologous Tricyclic Imides

The crystal structures of 3,4,6a,7,10,10a-hexahydro-7,10-epoxypyrimido[2,1-a]isoindol-6(2H)-one, C11H12N2O2, and 2-(2-aminoethyl)-3a,4,7,7a-tetrahydro-1H-4,7-epoxyisoindole-1,3(2H)-dione, C10H12N2O3, two tricyclic imides, show one and two molecules in the asymmetric unit, respectively. Intermolecular hydrogen-bonding interactions are observed in both compounds.National Science Foundation (grant No. CHE-0741973)The Welch Foundation (grant No. F-1631)National Science Foundation (grant No. CHE-0847763)ChemistryBiochemistr

First Case of Multiple Resistance to EPSPS and PSI in Eleusine indica (L.) Gaertn. Collected in Rice and Herbicide-Resistant Crops in Colombia

Eleusine indica is a highly competitive and difficult-to-control plant in annual and perennial crops. In Colombia, broad-spectrum herbicides, such as paraquat and glyphosate, have begun to present poor levels of control for this weed. The multiple resistance to glyphosate and paraquat, the increase in herbicide performance with adjuvants (Retenol® and Trend® 90), and alternative herbicides were evaluated in a resistant (R) population of E. indica collected in rice fields, which is rotated with herbicide-resistant (HR) crops. Based on plant mortality, the R population was 9.8 and 7.2 times more resistant than susceptible (S) plants to glyphosate and paraquat, respectively. R plants accumulated 4.2 less shikimic acid and had at least 70% less electrolyte leakage than S plants when they were exposed to glyphosate and paraquat, respectively. Both adjuvants increased the foliar retention of herbicides. In addition, adjuvants also increased the performance of glyphosate effectiveness between 22% and 58% and that of paraquat from 61% to 100%. Alternative herbicides (atrazine, clethodim, imazamox, diuron, flazasulfuron, glufosinate, oxyfluorfen, quizalofop, and tembotrione) provided high levels of control in both populations of E. indica. This is the first case of multiple resistant E. indica confirmed in Colombia. Adjuvants improved the leaf retention and efficacy of glyphosate and paraquat. In summary, the alternative herbicides evaluated in this study should be adopted by Colombian farmers and provide additional herbicide modes-of-action to combat future resistance

Actinobacteria from brazilian cerrado soil: potential biocontrol agent to soybean and wheat diseases.

Abstract: The Cerrado biome, located in the Middle West region of Brazil, has showed a significant increase in soybean (Glycine maxx L. Merrill) and wheat (Triticuma estivum L.) production. In these crops the fungi Sclerotinia sclerotiorum and Magnaphorte grisea constitute severe phytosanitary problems, once they commonly inhabit the soil favored by their latency structures. These fungi are responsible for great economic losses during the entirely crop production cycle. The soil is considered a complex habitat due to the extensive variety of physical, chemical and microbiological processes, and is essential for different forms of life, once this ecosystem offers great support to the maintenance of microbiological diversity. Actinobacteria, one of the main Phylum present in the soil, are currently highlighted because of their great biotechnological relevance. They are responsible for many of known antibiotics and by being great enzymatic producers with several industrial applications. We obtained many microorganisms with biological activity from an isolation process of the Cerrado soil. One of them was the Actinobacteria identified as 3-AS-4. It showed significant antagonistic activity in vitro and its crude extract, obtained with ethyl acetate at pH 3, strongly inhibited S. sclerotiorum and M. grisea growth. Moreover, this isolate was able to solubilize organic and inorganic phosphorus and presented chitinolytic and cellulolytic activity. These results highlight the broad and diversity mechanisms of action of this isolate as an interesting potential tool to integrate management of diseases. The knowledge of the ecological aspects of this Actinobacteria, such as the interaction with other members of the rhizosphere from these crops, and the variation of the soil community in the presence of this isolate, is essential to a possible future application as a new tool to biological control of diseases

Strong disorder renormalization group study of aperiodic quantum Ising chains

We employ an adaptation of a strong-disorder renormalization-group technique in order to analyze the ferro-paramagnetic quantum phase transition of Ising chains with aperiodic but deterministic couplings under the action of a transverse field. In the presence of marginal or relevant geometric fluctuations induced by aperiodicity, for which the critical behavior is expected to depart from the Onsager universality class, we derive analytical and asymptotically exact expressions for various critical exponents (including the correlation-length and the magnetization exponents, which are not easily obtainable by other methods), and shed light onto the nature of the ground state structures in the neighborhood of the critical point. The main results obtained by this approach are confirmed by finite-size scaling analyses of numerical calculations based on the free-fermion method