Spin Trapping Isotopically-Labelled Nitric Oxide Produced from [15n]L-Arginine and [17ojdioxygen by Activated Macrophages Using a Water Soluble Fe++-Dithiocarbamate Spin Trap

The unique capabilities of EPR spin trapping of nitric oxide based on a ferrous-dithiocarbamate spin trap have been demonstrated in a study verifying the source of the nitrogen and oxygen atoms in nitric oxide produced from activated macrophages. Spin trapping experiments were performed during nitric oxide generation from activated mouse peritoneal macrophages using the ferrous complex of N-methyl D-glucam-ine dithiocarbamate as a spin trap. When ¹⁵N-substituted arginine was given to the activated macrophages in the presence of the spin trap, a characteristic EPR spectrum of the nitric oxide spin adduct was obtained, which indicates the presence of the ^l5N atom in the nitric oxide molecule. The hyperfine splitting (hfs) constant of the ^l5N nucleus was 17.6 gauss. When ^l7O-containing dioxygen (55%) was supplied to the medium, an EPR spectrum consistent with the “O-substituted nitric oxide spin adduct was observed in the composite spectrum. The hfs of “O was estimated to be 2.5 gauss. The ^l4NO spin adduct observed after prolonged incubation in the medium which contains [^l5N]L-arginine as the only extracellular source of arginine demonstrates that arginine is recycled through its metabolite in activated macrophages.     

格网尺度下典型旅游城市生态服务价值估算和时空分异特征——以三亚为例

以典型旅游城市三亚市为案例地，利用2006-2018年4期Landsat遥感影像数据，借助ENVI、ArcGIS平台定量识别土地利用演变特征，在1km×1km格网尺度下估算旅游地生态系统服务价值，并结合空间探索性数据分析揭示生态系统服务价值时空分异特征及其与旅游地发展的时空耦合关系。结果表明：（1）2006-2018年间，三亚市生态系统服务价值总量呈逐年下降趋势，由6.73×10⁹元降至5.76×10⁹元，累计减少9.78×10⁸元；（2）空间格局上，三亚市呈"南低北高"空间分异格局，2006-2018年增值区域连片分布于崖州区、天涯区、吉阳区南部区域，且呈逐年减少趋势，减值区域集聚于天涯区东北部、海棠区；（3）空间集聚上，生态系统服务价值截面各年份均呈显著空间正相关且相关性先降后增。高高集聚区位于天涯区北部区域，低低集聚区分布于沿海、海湾地区；（4）旅游发展与生态系统服务价值时空演化特征关联性较强。三亚市天涯区北部林地生态环境良好，生态系统服务价值略有下降但绝对数值稳定，是生态系统服务价值主要来源；旅游发展较为迅速的三亚湾、崖州湾以及海棠湾，相对增值区域较多，但绝对生态系统服务价值损失显著，严重滞后于其他区域。     

Opportunistic use of camera traps to assess habitat-specific mammal and bird diversity in northcentral Namibia

In northcentral Namibia, Waterberg Plateau Park (WPP) is a protected area that acts as a refuge for rare and endangered species, while the farmlands surrounding the Park are managed for livestock production, but support populations of wildlife for game farming, trophy hunting, and conservation. During June–October 2006, camera-traps were set within and surrounding WPP to assess leopard (Panthera pardus) density (n = 19 camera stations and 946 camera-trap-nights). Fortuitously, photographic results (2,265 photos of identifiable mammal (n = 37) and bird (n = 25) species) allowed us to assess aspects of species diversity and differences among the Park, the farmland areas along the Waterberg Plateau escarpment, and the flatlands surrounding the escarpment. Species composition among the three areas was markedly different, and made sense with respect to differences in habitat and management features. Camera-trapping efforts, although intended for a narrow purpose, may also provide a rather robust record of differences in mammal and bird diversity in adjacent habitats and can be incorporated into long-term monitoring programs.     

Detection of superoxide production in stimulated and unstimulated living cells using new cyclic nitrone spin traps

Reactive oxygen species (ROS), including superoxide anion and hydrogen peroxide (H₂O₂), have a diverse array of physiological and pathological effects within living cells depending on the extent, timing, and location of their production. For measuring ROS production in cells, the ESR spin trapping technique using cyclic nitrones distinguishes itself from other methods by its specificity for superoxide and hydroxyl radical. However, several drawbacks, such as the low spin trapping rate and the spontaneous and cell-enhanced decomposition of the spin adducts to ESR-silent products, limit the application of this method to biological systems. Recently, new cyclic nitrones bearing a triphenylphosphonium (Mito-DIPPMPO) or a permethylated β-cyclodextrin moiety (CD-DIPPMPO) have been synthesized and their spin adducts demonstrated increased stability in buffer. In this study, a comparison of the spin trapping efficiency of these new compounds with commonly used cyclic nitrone spin traps, i.e., 5,5-dimethyl-1-pyrroline N-oxide (DMPO), and analogs BMPO, DEPMPO, and DIPPMPO, was performed on RAW 264.7 macrophages stimulated with phorbol 12-myristate 13-acetate. Our results show that Mito-DIPPMPO and CD-DIPPMPO enable a higher detection of superoxide adduct, with a low (if any) amount of hydroxyl adduct. CD-DIPPMPO, especially, appears to be a superior spin trap for extracellular superoxide detection in living macrophages, allowing measurement of superoxide production in unstimulated cells for the first time. The main rationale put forward for this extreme sensitivity is that the extracellular localization of the spin trap prevents the reduction of the spin adducts by ascorbic acid and glutathione within cells.     

Detection of the Ethyl-and Pentyl-Radical Adducts of α-(4-Pyridyl-1-Oxide)-N-Ter J-Butylnitrone in Rat-Liver Microsomes Treated with ADP,NADPH and Ferric Chloride

HPLC-EPR analyses of the reaction mixtures of microsomal suspensions incubated with ADP, ferric chloride, NADPH and α-(4-pyridyl-1-oxide)-N-tert-butylnitrone (4-POBN) were performed. In the elution pattern of the reaction mixture, three peaks (peaks 1, 2 and 3) were detected. The radical adducts (1 and 3) were identified as being the pentyl- and ethyl-radical adducts of 4-POBN by comparing their retention times with those of the authentic radical adducts.     

The use of barrier-connected pitfall trapping for sampling predatory beetles and spiders

The efficiency of barrier-connected pitfall trapping was compared to conventional single traps or arrays. For ground-active beetles, the use of a pitfall system incorporating a wetting agent with five traps arranged in a cross formation connected by plastic barriers was more efficient than a single dry trap by at least an order of magnitude and at least twice as efficient as five traps without connecting barriers. It is argued that the efficiency of pitfall trapping may be improved markedly by using barrier-connected traps, particularly for some carabid and staphylinid beetles and lycosid spiders. Capture of linyphiids was not improved by the use of barriers and was dependent only on the use of wetting agent and number of traps used.     

Possible mechanisms for strand-breaks in DNA induced by stirring

When aqueous solutions of DNA are stirred at room temperature, strand breaks occur extensively. Using various spin-traps, coupled with epr spectroscopy, we have shown that this does not proceed via homolysis. It is suggested that breaks occur by hydrolysis at strongly bent regions, momentarily induced by the stirring.     

Evaluation of Superoxide Scavenging Activity of OPC-14117 By Electron Spin Resonance Technique

OPC-14117 is a potent drug which has both brain function activating effect and protective effect against cerebral ischemia. Occurrences of these effects might be expected due to superoxide dismutase-like activity of OPC-14117. The present study has been conducted to evaluate the active oxygen scavenging activity of OPC-14117 and to explain the mechanisms of its pharmacological activities. The reaction of OPC-14117 and superoxide anion. generated in potassium superoxide, was examined by electron spin resonance technique at both liquid nitrogen (77 K) and room (22°C) temperatures. OPC-14117 showed a higher superoxide scavenging activity than that of α-tocopherol in an aprotic solvent system. The active moiety of OPC-14117 to provide the scavenging effect was found due to the phenolic hydroxyl group of its indan skeleton.