Climate-forced variability of ocean hypoxia

Oxygen (O(2)) is a critical constraint on marine ecosystems. As oceanic O(2) falls to hypoxic concentrations, habitability for aerobic organisms decreases rapidly. We show that the spatial extent of hypoxia is highly sensitive to small changes in the ocean's O(2) content, with maximum responses at suboxic concentrations where anaerobic metabolisms predominate. In model-based reconstructions of historical oxygen changes, the world's largest suboxic zone, in the Pacific Ocean, varies in size by a factor of 2. This is attributable to climate-driven changes in the depth of the tropical and subtropical thermocline that have multiplicative effects on respiration rates in low-O(2) water. The same mechanism yields even larger fluctuations in the rate of nitrogen removal by denitrification, creating a link between decadal climate oscillations and the nutrient limitation of marine photosynthesis.     

A Redox Fuel Cell That Operates with Methane as Fuel at 120{degrees}C

Platinum black efficiently catalyzes the oxidation of methane by iron(III) to generate carbon dioxide and eight equivalents of iron(II) in solutions of sulfuric acid in water. The rate of oxidation increases over 4 hours to reach approximately 4.83 x 10(-2) moles of iron(II) per gram atom of surface platinum per second. A redox fuel cell was assembled that used this reaction in a liquid reformer to generate soluble reducing equivalents of iron(II) from methane, which was electrochemically oxidized to iron(III) in the cell. A vanadium(V)-(IV)-nitric acid-O(2) redox system catalyzed the electrochemical reduction of O(2). The open-circuit voltage of the cell was 0.48 volt, and the maximum power output of the cell was 8.1 milliwatts per cubic centimeter of graphite felt electrode.     

基于聚类分析的云南省荔枝栽培气候区划研究

 根据荔枝生长发育与气候条件的关系,确定荔枝栽培的气候区划。选择云南134个气候站点,将其中51个30年平均最低气温高于-4 ℃的气候站点划分为可栽培区,另外83个30年平均最低气温低于-4 ℃的气候站点划分为不宜栽培区。再根据19个气候要素,应用聚类分析将51个可栽培区划分为适宜区(Ⅰ),较适宜区(II),次适宜区(III)和较次适宜区(Ⅳ)等4个等级。其中,适宜区、较适宜区和次适宜区可以作为云南省荔枝生产的主要区域。     

Crystal and molecular structure of a double complex of manganese with phthalocyanato and pyridine ligands

A crystalline solid, formed by oxidation of phthalocyanatomanganese(II) in pyridine, has been identified as phthalocyanatopyridinemanganese(III)-micro-oxo-phthalocyanatopyridinemanganese(III)dipyridinate(C(74)H(42)Mn(2)N(18)O2C(5)H(5)N) byx-ray diffraction methods. This novel molecule consists of two manganese complexes joined by an essentially linear Mn-O-Mn bridge. Its structure may have some relation to oxidation processes in biological systems.     

不同水平低中心静脉压对肝叶切除术患者失血量的影响

目的 观察肝叶切除患者术中不同水平低中心静脉压（CVP）对失血量的影响.方法 80例择期肝叶切除手术患者随机分为I组（CVP=1 cmH2O）、Ⅱ组（CVP=2 cmH2O）、Ⅲ组（CVP=3 cmH2O）、Ⅳ组（CVP=4 cmH2O）,每组20例;术中控制CVP水平,并维持动脉收缩压（SBP）≥90mmHg或平均动脉压（MAP）≥60mmHg.记录肝实质离断前、中、后出血量及单位横截面积出血量.结果 肝实质离断过程中,Ⅲ、Ⅳ组的MAP水平明显高于Ⅰ组和Ⅱ组（P＜0.01）;Ⅰ、Ⅱ、Ⅲ组间的出血量以及单位横截面积出血量差异无统计学意义（P＞0.05）,但均明显少于Ⅳ组（P＜0.01）.结论 控制性低CVP技术可明显减少肝叶切除术中失血量,3 cmH2O CVP可维持围术期血流动力学及减少术中失血量.     

Interstitial nitrate profiles and oxidation of sedimentary organic matter in the eastern equatorial atlantic

Pore-water nitrate concentrations in six pelagic eastern equatorial Atlantic cores increase from bottom water values (22 micromolar) to 40 micromolar at a depth of about 5 centimeters, then decrease to undetectable levels at depths as shallow as 40 centimeters. These nitrate concentrations and concentration gradients reflect zones of oxygen reduction, nitrate reduction, and sulfate reduction in the sediments. The estimated benthic flux of nitrate to the ocean from our data is much less than the total globalflux of nitrate to deep waters, even though these equatorial sediments underlie a productive upwelling zone. The estimated denitrification rate in our study area suggests that pelagic sediments may be important sites of marine denitrification.     

观赏鱼金鲫饲料配方的优化试验

以价廉的菜籽饼作为主要蛋白质饲料原料之一,配制了Ⅰ、Ⅱ、Ⅲ、Ⅳ号4种饵料,用其分别饲喂4组金鲫,进行饲养试验。结果表明：用Ⅱ号饵料饲喂的金鲫相对增长率达到15.31%,饵料系数为1.93,显著优于其他各组。Ⅱ号饵料为最优配方。     

Soluble and colloidal iron in the oligotrophic North Atlantic and North Pacific

In the oligotrophic North Atlantic and North Pacific, ultrafiltration studies show that concentrations of soluble iron and soluble iron-binding organic ligands are much lower than previously presumed "dissolved" concentrations, which were operationally defined as that passing through a 0.4-micrometer pore filter. Our studies indicate that substantial portions of the previously presumed "dissolved" iron (and probably also iron-binding ligands) are present in colloidal size range. The soluble iron and iron-binding organic ligands are depleted at the surface and enriched at depth, similar to distributions of major nutrients. By contrast, colloidal iron shows a maximum at the surface and a minimum in the upper nutricline. Our results suggest that "dissolved" iron may be less bioavailable to phytoplankton than previously thought and that iron removal through colloid aggregation and settling should be considered in models of the oceanic iron cycle.     

Sequence-specific peptide cleavage catalyzed by an antibody

Monoclonal antibodies have been induced that are capable of catalyzing specific hydrolysis of the Gly-Phe bond of peptide substrates at neutral pH with a metal complex cofactor. The antibodies were produced by immunizing with a Co(III) triethylenetetramine (trien)-peptide hapten. These antibodies as a group are capable of binding trien complexes of not only Co(III) but also of numerous other metals. Six peptides were examined as possible substrates with the antibodies and various metal complexes. Two of these peptides were cleaved by several of the antibodies. One antibody was studied in detail, and cleavage was observed for the substrates with the trien complexes of Zn(II), Ga(III), Fe(III), In(III), Cu(II), Ni(II), Lu(III), Mg(II), or Mn(II) as cofactors. A turnover number of 6 x 10(-4) per second was observed for these substrates. These results demonstrate the feasibility of the use of cofactor-assisted catalysis in an antibody binding site to accomplish difficult chemical transformations.     

A synthetic model of the Mn₃Ca subsite of the oxygen-evolving complex in photosystem II

Within photosynthetic organisms, the oxygen-evolving complex (OEC) of photosystem II generates dioxygen from water using a catalytic Mn(4)CaO(n) cluster (n varies with the mechanism and nature of the intermediate). We report here the rational synthesis of a [Mn(3)CaO(4)](6+) cubane that structurally models the trimanganese-calcium-cubane subsite of the OEC. Structural and electrochemical comparison between Mn(3)CaO(4) and a related Mn(4)O(4) cubane alongside characterization of an intermediate calcium-manganese multinuclear complex reveals potential roles of calcium in facilitating high oxidation states at manganese and in the assembly of the biological cluster.     

益生菌·低聚木糖制剂对仔猪生长性能和黄白痢的预防效果

选用2胎龄斯格母猪20头,随机分成5个处理,每处理4次重复,仔猪出生3 d内吃乳前饲喂1 mL液态微生态制剂,诱食后在基础日粮中分别添加0.1% 微胶囊(Ⅰ)、0.05% 低聚木糖(Ⅱ)、0.1% 微胶囊和0.05% 低聚木糖(Ⅲ)、0.1% 菌粉和0.05% 低聚木糖(Ⅳ)及对照组(Ⅴ),观察其对仔猪生长性能、黄白痢发生率和死亡率的影响.结果表明:7日龄内饲喂菌液对体质量增加无明显影响(P>0.05),黄白痢发生率与对照组差异不显著,但仔猪死亡率明显低于对照组(P<0.01).8～28日龄Ⅲ组与Ⅰ、Ⅱ、Ⅴ组仔猪体质量增加差异显著(P<0.05),所有试验组与对照组黄白痢发生率差异极显著(P<0.01),Ⅲ、Ⅳ组与Ⅰ、Ⅱ组黄白痢发生率差异极显著(P<0.01);29～40日龄Ⅲ组与Ⅰ、Ⅱ、Ⅳ、Ⅴ组仔猪体质量增加差异显著(P<0.05),Ⅲ组仔猪黄白痢发生率与其他试验组和对照组差异极显著(P<0.01);试验Ⅰ、Ⅱ、Ⅳ组与Ⅴ组差异显著(P<0.05).     

Microheterogeneity of singlet oxygen distributions in irradiated humic acid solutions

Singlet oxygen (1O2) is a highly reactive species formed through solar irradiation of organic matter in environmental waters. Implicated in a range of reactions, it has proven difficult to quantify its spatial distribution in natural waters. We assessed the microheterogeneous distribution of 1O2 in irradiated solutions containing chromophoric dissolved organic matter (CDOM) by using molecular probes of varying hydrophobicity. The apparent 1O2 concentrations ([1O2]app), measured by recently developed hydrophobic trap-and-trigger chemiluminescent probe molecules, were orders of magnitude higher than those measured by the conventional hydrophilic probe molecule furfuryl alcohol. The differential [1O2]app values measured by these probes reflect a steep concentration gradient between the CDOM macromolecules and the aqueous phase. A detailed kinetic model based on the data predicts probabilistic 1O2 distributions under different solvent conditions.     

Zero-mode waveguides for single-molecule analysis at high concentrations

Optical approaches for observing the dynamics of single molecules have required pico- to nanomolar concentrations of fluorophore in order to isolate individual molecules. However, many biologically relevant processes occur at micromolar ligand concentrations, necessitating a reduction in the conventional observation volume by three orders of magnitude. We show that arrays of zero-mode waveguides consisting of subwavelength holes in a metal film provide a simple and highly parallel means for studying single-molecule dynamics at micromolar concentrations with microsecond temporal resolution. We present observations of DNA polymerase activity as an example of the effectiveness of zero-mode waveguides for performing single-molecule experiments at high concentrations.     

日粮中不同黄芪水平对家兔血液理化指标及生长性能的影响

选用体重相近的90日龄生长发育健康的中国白兔32只,雌雄各半,随机分为对照Ⅰ组、试验Ⅱ组、Ⅲ组、Ⅳ组,每天依次在基础日粮中一次性添加0、10、20、30 g的黄芪粉,试验期30 d.结果显示,各试验组与对照Ⅰ组相比,明显提高了血液中血红蛋白的含量,各组间存在极显著差异(P＜0.01);随添加黄芪粉剂量的加大,血清中白蛋白含量相应增加,Ⅲ、Ⅳ组间差异不显著(P＞0.05),其余组间存在极显著差异(P＜0.01);血清总蛋白、天门冬氨酸氨基转移酶及乳酸脱氢酶含量均呈现先增高后降低的趋势,各组间存在极显著差异(P＜0.01);血清葡萄糖含量变化趋势同总蛋白,当日添加量在20、30 g时,血清中葡萄糖的含量趋于稳定;Ⅱ组末重、净增重、平均日增重分别与Ⅰ、Ⅲ、Ⅳ组差异显著(P＜0.05),Ⅰ、Ⅲ、Ⅳ组间差异不显著(P＞0.05),Ⅱ、Ⅲ、Ⅳ组分别比对照Ⅰ组增重提高25.0%、12.5%、8.3%.基础日粮中添加黄芪粉以每日10 g为好,能显著提高饲料报酬及家兔的平均日增重.     

Accumulation of Mn(II) in Deinococcus radiodurans facilitates gamma-radiation resistance

Deinococcus radiodurans is extremely resistant to ionizing radiation. How this bacterium can grow under chronic gamma radiation [50 grays (Gy) per hour] or recover from acute doses greater than 10 kGy is unknown. We show that D. radiodurans accumulates very high intracellular manganese and low iron levels compared with radiation-sensitive bacteria and that resistance exhibits a concentration-dependent response to manganous chloride [Mn(II)]. Among the most radiation-resistant bacterial groups reported, Deinococcus, Enterococcus, Lactobacillus, and cyanobacteria accumulate Mn(II). In contrast, Shewanella oneidensis and Pseudomonas putida have high iron but low intracellular manganese concentrations and are very sensitive. We propose that Mn(II) accumulation facilitates recovery from radiation injury.     

考克氏菌木聚糖酶发酵条件的优化

从海洋微生物中筛选到1株具有木聚糖酶活性的考克氏菌(Kocuria sp.Mn22),用单交法研究了不同单因素对该菌株产木聚糖酶的影响.结果表明:用水不溶性和醇不溶性木聚糖诱导该菌株比水不溶性木聚糖诱导产酶量高;较低浓度的Tween 80对该菌株产木聚糖酶具有诱导作用,而高浓度的Tween 80会抑制木聚糖酶的产生;Triton X-100具有抑制作用.对考克氏菌液体发酵条件的正交试验表明:以水不溶性和醇不溶性木聚糖为碳源,牛肉膏为氮源,pH 8.5,Tween 80添加量为0.2%,发酵68 h后,菌株的最高酶活力可达到148.7 IU/mL.     

复方甘草酸单胺可溶性粉对恩诺沙星联合LPS 致鸡肝损伤的免疫调节

【目的】探索恩诺沙星联合脂多糖粗提液（lipopolysaccharide crude extract,LPS）诱导鸡肝损伤中机体免疫功能变化,并研究复方甘草酸单胺粉（compound ammonium glycyrrhizin soluble powder,CAG）护肝及免疫调节作用和机理。【方法】104 羽海蓝蛋鸡随机分为空白组（I）,模型组（II）,CAG预防组（III）、CAG治疗高、低剂量（IV、V）组,除I组外,各组连续3 d灌服恩诺沙星（100 mg•kg-1,1次/天）,于第3次灌药时腹注LPS（4 mL•kg-1）诱发肝损伤,III组建模前3 d以40 mg•L-1混饮CAG,持续至建模结束;IV、V组腹注LPS后分以22.5、7.5 mg•kg-1灌服CAG,2 次/天,重复3 d。建模后6、24、48 h采血并剖检。【结果】与I组相比,II组鸡血清ALT、AST、TNF-α、IL-1、IL-6水平 6、24和48h显著升高,外周血中CD3+、CD4+和CD8+ T细胞百分含量 6和24 h显著降低,48 h显著升高,肝组织病变明显。与II组相比：III组ALT、TNF-α 和IL-6 6 h,AST 6和24 h,CD3+、CD4+ 和CD8+ T细胞48 h降低显著;IV组ALT、AST、TNF-α、IL-6 24和48 h,IL-1、CD3+、 CD4+ 和CD8+ T细胞 48 h 显著降低,CD3+ T细胞6和24 h,CD4+ T细胞24 h显著升高;V组中CD8+ T细胞在48 h显著降低;其余差异不显著。IV组较其它组肝组织病变有最大改善。【结论】恩诺沙星联合LPS诱发肝损伤同时致炎性细胞因子TNF-α、IL-1、IL-6释放和CD3+细胞及其亚群CD4+ 和CD8+发生先低于正常水平,后又显著高于正常水平现象,复方甘草酸单胺可能通过抑制以上3种炎性因子释放,双向调节外周血T细胞亚群恢复正常水平而发挥护肝作用,但作用与给药剂量和时机相关。     

High-temperature molecular magnets based on cyanovanadate building blocks: spontaneous magnetization at 230 k

The molecular-based magnetic materials Cs(2)Mn(||)[V(||)(CN)(6)] (1) and (Et(4)N)(0.5)Mn(l.25)- [V(CN)(5)].2H(2)O (2) (where Et is ethyl) were prepared by the addition of manganese(II) triflate to aqueous solutions of the hexacyanovanadate(II) ion at 0 degrees C. Whereas 1 crystallizes in a face-centered cubic lattice, 2 crystallizes in a noncubic space group. The cesium salt (1) has features characteristic of a three-dimensional ferrimagnet with a Néel transition at 125 kelvin. The tetraethylammonium salt (2) also behaves as a three-dimensional ferrimagnet with a Néel temperature of 230 kelvin; only two other molecular magnets have higher magnetic ordering temperatures. Saturation magnetization measurements indicate that in both compounds the V(II) and high-spin Mn(II) centers are antiferromagnetically coupled. Both 1 and 2 exhibit hysteresis loops characteristic of soft magnets below their magnetic phase-transition temperatures. The high magnetic ordering temperatures of these cyano-bridged solids confirm that the incorporation of early transition elements into the lattice promotes stronger magnetic coupling by enhancing the backbonding into the cyanide pi* orbitals.     

A manganese(IV)/iron(III) cofactor in Chlamydia trachomatis ribonucleotide reductase

In a conventional class I ribonucleotide reductase (RNR), a diiron(II/II) cofactor in the R2 subunit reacts with oxygen to produce a diiron(III/IV) intermediate, which generates a stable tyrosyl radical (Y*). The Y* reversibly oxidizes a cysteine residue in the R1 subunit to a cysteinyl radical (C*), which abstracts the 3'-hydrogen of the substrate to initiate its reduction. The RNR from Chlamydia trachomatis lacks the Y*, and it had been proposed that the diiron(III/IV) complex in R2 directly generates the C* in R1. By enzyme activity measurements and spectroscopic methods, we show that this RNR actually uses a previously unknown stable manganese(IV)/iron(III) cofactor for radical initiation.     

Identification of hydroxymethanesulfonate in fog water

Previous studies have suggested that hydroxymethanesulfonate ion (HMSA) can be an important species in fog and cloud water. Formation of HMSA explains observed excesses of sulfur in the S(IV) state (+4 oxidation state) and formaldehyde (CH(2)O) in fogs and clouds. HMSA was determined in fog water by a novel ion-pairing chromatographic technique. Concentrations in samples collected in Bakersfield, California, within 5 kilometers of major sources of sulfur dioxide (SO(2)), were as high as 300 micromoles per liter. Total CH(2)O and S(IV) concentrations, which were measured independently, ranged from 10 to 200 and 5 to more than 300 micromoles per liter, respectively. Concentrations of CH(2)O, S(IV), and HMSA at Buttonwillow, California, which is 15 kilometers from the nearest source of SO(2), were less than those at Bakersfield but not absent. These data confirm that HMSA forms in atmospheric water droplets and can reach appreciable concentrations. HMSA represents an important source of acidity for water droplets and may also play a role in long-distance transport and transformation of SO(2).