Bacterial Active Community Cycling in Response to Solar Radiation and Their Influence on Nutrient Changes in a High-Altitude Wetland

Indexación: Web of Science; Scopus.Microbial communities inhabiting high-altitude spring ecosystems are subjected to extreme changes in solar irradiance and temperature throughout the diel cycle. Here, using 16S rRNA gene tag pyrosequencing (cDNA) we determined the composition of actively transcribing bacteria from spring waters experimentally exposed through the day (morning, noon, and afternoon) to variable levels of solar radiation and light quality, and evaluated their influence on nutrient recycling. Solar irradiance, temperature, and changes in nutrient dynamics were associated with changes in the active bacterial community structure, predominantly by Cyanobacteria, Verrucomicrobia, Proteobacteria, and 35 other Phyla, including the recently described Candidate Phyla Radiation (e.g., Parcubacteria, Gracilibacteria, OP3, TM6, SR1). Diversity increased at noon, when the highest irradiances were measured (3.3-3.9 H', 1125 W m(-2)) compared to morning and afternoon (0.6-2.8 H'). This shift was associated with a decrease in the contribution to pyrolibraries by Cyanobacteria and an increase of Proteobacteria and other initially low frequently and rare bacteria phyla (< 0.5%) in the pyrolibraries. A potential increase in the activity of Cyanobacteria and other phototrophic groups, e.g., Rhodobacterales, was observed and associated with UVR, suggesting the presence of photo activated repair mechanisms to resist high levels of solar radiation. In addition, the percentage contribution of cyanobacterial sequences in the afternoon was similar to those recorded in the morning. The shifts in the contribution by Cyanobacteria also influenced the rate of change in nitrate, nitrite, and phosphate, highlighted by a high level of nitrate accumulation during hours of high radiation and temperature associated with nitrifying bacteria activity. We did not detect ammonia or nitrite oxidizing bacteria in situ, but both functional groups (Nitrosomona and Nitrospira) appeared mainly in pyrolibraries generated from dark incubations. In total, our results reveal that both the structure and the diversity of the active bacteria community was extremely dynamic through the day, and showed marked shifts in composition that influenced nutrient recycling, highlighting how abiotic variation affects potential ecosystem functioning.http://journal.frontiersin.org/article/10.3389/fmicb.2016.01823/ful

Bacterial Active Community Cycling in Response to Solar Radiation and Their Influence on Nutrient Changes in a High-Altitude Wetland

This research was supported by funds granted by Comisión Nacional de Investigación Científica y Tecnológica (CONICYT, Chile) FONDECYT grants N° 1110824, 1140179, 11110190, 1100358, 1110953, and 1140356; CONICYT-PIA FB0001

Crystallographic and metallurgical characterization of radiation detector grade cadmium telluride materials

Radiation detector grade CdTe crystals are characterized by several crystallographic and metallurgical techniques including infrared microscopy, dislocation etch pitting and X-ray diffraction. Results are presented for a set of 50 detectors fabricated from an ingot produced by the High Pressure Bridgman method. Data on the temperature dependence of leakage current and pulse height analysis are presented, along with measurements of room temperature charge transport properties. Attempts to relate crystal structure to detector performance discussed

Molekularstrahlepitaxie von Hochtemperatursupraleitern Abschlussbericht

The document discusses the preparation of DyBa_2Cu_3O_7-#delta#-films by MBE in detail. The structural properties of the high-temperature superconducting films are examined by means of the atomic scanning tunneling and the atomic force microscopy, as well as by means of X-ray techniques, and are brought in relation with the superconducting properties. The surface of the SrTiO_3-substrates is studied in detail by atomic force microscopy. (orig.)In der vorliegenden Arbeit wird die Praeparation von DyBa_2Cu_3O_7_-_#delta#-Filmen durch MBE ausfuehrlich diskutiert. Die strukturellen Eigenschaften der HTSL-Filme werden mit der atomaren Tunnel- und Kraftmikroskopie sowie durch Roentgentechniken untersucht und mit den spuraleitenden Eigenschaften in Verbindung gebracht. Die Oberflaeche der SrTiO_3-Substrate wird mit dem AFM eingehend studiert. (orig.)Available from TIB Hannover: F95B625+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Forschung und Technologie (BMFT), Bonn (Germany)DEGerman