A helical filamentous cyanobactericidal bacterium was isolated from Dianchi Lake, a eutrophic freshwater lake in Kunming City of the Yunnan Province in China using a special solid medium. This species was designated strain PdY3. This bacterium was identified as a novel Saprospira sp. on the basis of its morphological characteristics and 16S rDNA sequence. Strain PdY3 showed apparent group behavior on the solid medium, forming orderly, bundle-like group structures. These bundles moved as groups. Individuals in a bundle responded to the bundle as a whole. PdY3 also showed group behavior and formed a three-dimensional reticular structure when co-cultured with Anabaena in liquid media. This helical bacterium lysed cyanobacteria through direct contact and its group behavior greatly accelerated the cyanobactericidal process. Our experiments showed that PdY3 caused lysis of 64% of Anabaena cells within 1 day and that its cyanobactericidal range was broad. These results underscore potential application of Saprospira on the control of blooms of cyanobacteria. PdY3 group behavior might allow a more efficient capture of bacterial prey.
Organosulfates are observed in studies of pinonaldehyde reactions with acidic sulfate aerosols using aerosol mass spectrometry, during which a significant fraction of the pinonaldehyde reaction products were found to consist of organosulfate compounds that account for 6 - 51% of the initial SO4= mass. Resultant aerosol mass spectra were consistent with proposed sulfate ester mechanisms, which likely form stable products. The existence of organosulfates was also confirmed in studies of the reaction system in bulk solution. The formation of organosulfates suggests that conventional inorganic SO4= chemical analysis may underestimate total SO4= mass in ambient aerosols.
Song L-S, Sobie EA, McCulle S, Lederer WJ, Balke WC, Cheng H. Orphaned ryanodine receptors in the failing heart. Proceedings of the National Academy of Sciences of the United States of America [Internet]. 2006;(11):4305-4310. 访问链接
The Pacific 2001 Air Quality Study was undertaken to characterize the physical and chemical properties of particulate matter in the Lower Fraser Valley (LFV) airshed of British Columbia. Aerosol transport in the LFV was observed to occur through several regional scale mechanisms, including seabreeze-landbreeze flows, upslope-downslope flows and north-south valley flows. Enhanced aerosol concentrations were observed in the eastern portion of the LFV, the north-south tributary valleys and the Gulf/San Juan islands convergence zone. Particle composition was found to vary according to proximity to emission sources relative to surface flows. Approximately half of the particle mass was comprised of organic carbon, with the rest being inorganic species. Sodium nitrate was an important component of the coarse particle fraction, while ammonium sulphate was concentrated in the fine fraction. A broad suite of organic substances were detected, and both anthropogenic and biogenic sources were found to contribute to secondary organic aerosol fort-nation. Particle formation and growth was observed to occur via nucleation, condensation and coagulation. In general, the western part of the LFV airshed was dominated by combustion-related compounds, sea salt chemistry and organics (both anthropogenic and biogenic), while the eastern part of the airshed was dominated by NH3 chemistry and biogenic organics. The extent of processing of air masses was found to increase in a west to east direction, although the occasional accumulation of photochemically aged pollutants in the Gulf/San Juan islands convergence zone was observed to reverse this gradient. NH3 was found not to be a limiting species in the formation of fine mode inorganic aerosols, suggesting that NH3 emission reductions would have to be substantial in order to confer a significant improvement in PM and visibility. This coupled with the non-linear relationships between NOx, VOC and secondary particulates, suggests that PM and visibility improvement in the LFV would most likely require concurrent reductions in NH3, SOx, NOx and VOC emissions. Crown Copyright (c) 2006 Published by Elsevier Ltd. All rights reserved.