Crystal structure of a carbon monoxide dehydrogenase reveals a [Ni-4Fe-5S] cluster

The homodimeric nickel-containing CO dehydrogenase from the anaerobic bacterium Carboxydothermus hydrogenoformans catalyzes the oxidation of CO to CO2. A crystal structure of the reduced enzyme has been solved at 1.6 angstrom resolution. This structure represents the prototype for Ni-containing CO dehydrogenases from anaerobic bacteria and archaea. It contains five metal clusters of which clusters B, B', and a subunit-bridging, surface-exposed cluster D are cubane-type [4Fe-4S] clusters. The active-site clusters C and C' are novel, asymmetric [Ni-4Fe-5S] clusters. Their integral Ni ion, which is the likely site of CO oxidation, is coordinated by four sulfur ligands with square planar geometry.     

The crystal structure of [Fe]-hydrogenase reveals the geometry of the active site

Biological formation and consumption of molecular hydrogen (H2) are catalyzed by hydrogenases, of which three phylogenetically unrelated types are known: [NiFe]-hydrogenases, [FeFe]-hydrogenases, and [Fe]-hydrogenase. We present a crystal structure of [Fe]-hydrogenase at 1.75 angstrom resolution, showing a mononuclear iron coordinated by the sulfur of cysteine 176, two carbon monoxide (CO) molecules, and the sp2-hybridized nitrogen of a 2-pyridinol compound with back-bonding properties similar to those of cyanide. The three-dimensional arrangement of the ligands is similar to that of thiolate, CO, and cyanide ligated to the low-spin iron in binuclear [NiFe]- and [FeFe]-hydrogenases, although the enzymes have evolved independently and the CO and cyanide ligands are not found in any other metalloenzyme. The related iron ligation pattern of hydrogenases exemplifies convergent evolution and presumably plays an essential role in H2 activation. This finding may stimulate the ongoing synthesis of catalysts that could substitute for platinum in applications such as fuel cells.     

7种砧木对红玛斯卡特葡萄生长与果实品质的影响

[目的]为根据市场要求选取适合红玛斯卡特的砧木嫁接提供理论依据和技术支撑.[方法]以‘Gloire’、‘225Ru’、‘101-14’、‘5BB’、‘5C’、‘110R’、‘沈530’为砧木试材,红玛斯卡特为接穗,并与自根苗相比较,分别对7种砧木嫁接植株的物候期、生长结果习性、果实内在和外在品质等进行调查分析和测定,研究砧木对红玛斯卡特葡萄生长和果实品质的影响.[结果]不同的砧木嫁接同一接穗性状表现差异较大.砧木‘Gloire’、‘225Ru’、‘101-14’能促早成熟,砧木‘5BB’、‘110R’稍延迟成熟.‘101-14’、‘110R’缓和其生长势,‘Gloire’、‘225Ru’、‘沈530’增强生长势.果穗增重、果粒增大、产量增加的有‘225Ru’、‘110R’、‘沈530’.‘225Ru’、‘110R’、‘沈530’果实着色较自根苗深红.所有嫁接苗VC含量都高于自根苗.[结论]综合以上现状,砧木‘225Ru’、‘11 0R’、‘沈530’优于自根苗扣其他砧木.     

大气CO2浓度和温度升高对水稻体内微量元素累积的影响

为明确水稻体内微量元素对未来气候变化的响应,应用T-FACE(Temperature and CO_2Free Air Controlled Enrichment)试验平台,以常规粳稻武运粳23为试材,研究大气CO_2浓度升高(对照+200μL·L~(-1))和增温(对照+1℃)对收获期水稻体内微量元素累积的影响。结果显示,高浓度CO_2促进了稻穗中微量元素的累积,2013年穗中Fe和2014年穗中Zn的累积量分别显著增加16.7%和30.8%;增温降低了水稻器官中元素的累积量,2013年穗中Fe以及叶中Mn和Zn的累积量显著下降,降幅分别为30.2%、40.2%和57.3%;CO_2+温度整体降低了营养器官中Fe、Mn和Zn的累积量,2013年叶中Zn累积量显著减少40.0%。另外,高浓度CO_2降低了籽粒中Fe的累积量,2013年Fe累积量显著下降47.5%,同时提高了Mn与Zn的累积量,2014年Zn累积量显著增加43.4%;增温明显降低了籽粒中Fe、Mn和Zn的累积量;CO_2+温度有降低籽粒中元素累积量的趋势,其中2013年降幅大于2014年。以上结果表明未来CO_2浓度升高可在一定程度上缓解增温导致的水稻体内微量元素累积下降的状况。     

测定时间对黑土区CO2和N2O排放通量的影响（英文）

[目的]探讨测定时间对黑土区CO2和N2O排放通量的影响,确定排放通量的最佳测定时间,以期为黑土区农田温室气体减排提供科学依据。[方法]以黑土区长期肥料定位试验为平台,采用静态箱式法研究了小麦3个关键生育期(抽穗期、灌浆期和成熟期)CO2和N2O排放的日变化动态,揭示不同测定时段黑土区CO2和N2O排放通量的差异。[结果]土壤CO2和N2O排放通量日变化较大,变化范围分别为CO2206~552mg(/m·2h)和N2O51~295μg(/m2·h)。在不同生育期CO2呈单峰曲线变化,峰值出现在中午12:00,峰谷出现在凌晨3:00;N2O排放通量在抽穗期白天较小,而夜间排放量大。如果不考虑小麦生育期对CO2和N2O排放通量的影响,测定CO2排放代表性时间段在6:00~8:00或16:00~21:00;测定N2O时间段在8:00~10:00或16:00~21:00;若同时测定CO2和N2O排放通量,最佳测定时间在16:00~18:00。若在通常的观测时间9:00~12:00进行观测,CO2和N2O的较正系数分别为0.81和0.90。[结论]该研究结果为黑土区农田温室气体减排提供了科学依据。     

基于CO2超临界萃取技术的康藏荆芥精油的提取研究

[目的]建立CO2超临界萃取技术提取康藏荆芥（Nepeta pratti Lèvl）精油的最佳工艺。[方法]采用正交试验优化CO2超临界萃取技术提取康藏荆芥精油的工艺。应用气相色谱-质谱联用技术分析康藏荆芥精油的主要成分及其含量,并与水蒸气蒸馏法、溶剂法所萃取的康藏荆芥精油的主要成分及其含量进行比较。[结果]利用CO2超临界萃取技术提取的荆芥精油的主要组分为：胡薄荷酮、薄荷酮、石竹烯、D-柠檬烯、反式-香芹醇、辣薄荷烯酮、大=牛儿烯D、2R-顺-5-甲基-2-（1-甲基乙基）环己酮、异胡薄荷酮、柠檬烯、1-辛烯-3-醇,松茸醇、2-环戊基环戊酮、石竹烯氧化物、dactylol、月桂烯,其含量分别为：45.21%、19.90%、1.89%、1.80%、1.49%、1.07%、0.81%、0.78%、0.65%、0.51%、0.51%、0.50%、0.47%、0.40%、0.21%。其中,萃取物中的萜类物质含量最高,可达76.20%。与传统提取法（水蒸气蒸馏法和溶剂浸提法）相比,应用CO2超临界萃取技术提取的康藏荆芥精油中的主要物质胡薄荷酮等含量较高,且萃取出来的物质种类相对较多。[结论]超临界萃取法简便可行,具有传质速率快、穿透能力强、选择性高、萃取效率高、操作温度低等特点。     

2种多肉植物在室内环境中的光合及蒸腾特性研究

[目的]研究多肉植物长寿花(Kalanchoe blossfeldiana'Sensation')和花蔓草(Aptenia cordifolia)在室内环境中的光合特性和蒸腾特性,为其室内应用提供理论依据。[方法]以观赏性好、市场拥有率高的多肉植物长寿花和花蔓草为试验材料,通过对室内不同环境中光强、温度、湿度的持续研究,得到了室内光分布的曲线变化图,选取其中具有代表性的室内不同光照强度环境作为试验区域,用LI-6400便携式光合系统测定仪测定试验材料的CO2净吸收速率和蒸腾速率的昼夜变化,分别计算昼夜的固碳量和蒸腾释水量。[结果]长寿花和花蔓草在不同光环境中蒸腾速率的昼夜变化趋势和CO2净吸收速率的昼夜变化相似;从吸收CO2方面考虑,在南向房间中长寿花和花蔓草均宜放在1 052～1 360μmol/(m2.s)的光环境中,在北向房间中长寿花则宜放于北窗区域,而花蔓草易放于东向窗附近区域;从降低空气湿度方面考虑,在南向房间中长寿花和花蔓草宜放在1 052～1 360μmol/(m2.s)的光环境中,在北向房间中花蔓草和长寿花则宜放于北窗区域,且长寿花在北向房间的北窗区域的蒸腾量要比在南向窗区的蒸腾量还多。[结论]该研究可为将长寿花和花蔓草更好地应用于室内设计提供指导。     

Elevated Eocene atmospheric CO2 and its subsequent decline

Quantification of the atmospheric concentration of CO2 ([CO2]atm) during warm periods of Earth's history is important because burning of fossil fuels may produce future [CO2]atm approaching 1000 parts per million by volume (ppm). The early Eocene (~56 to 49 million years ago) had the highest prolonged global temperatures of the past 65 million years. High Eocene [CO2]atm is established from sodium carbonate minerals formed in saline lakes and preserved in the Green River Formation, western United States. Coprecipitation of nahcolite (NaHCO3) and halite (NaCl) from surface waters in contact with the atmosphere indicates [CO2]atm > 1125 ppm (four times preindustrial concentrations), which confirms that high [CO2]atm coincided with Eocene warmth.     

Food for thought: lower-than-expected crop yield stimulation with rising CO2 concentrations

Model projections suggest that although increased temperature and decreased soil moisture will act to reduce global crop yields by 2050, the direct fertilization effect of rising carbon dioxide concentration ([CO2]) will offset these losses. The CO2 fertilization factors used in models to project future yields were derived from enclosure studies conducted approximately 20 years ago. Free-air concentration enrichment (FACE) technology has now facilitated large-scale trials of the major grain crops at elevated [CO2] under fully open-air field conditions. In those trials, elevated [CO2] enhanced yield by approximately 50% less than in enclosure studies. This casts serious doubt on projections that rising [CO2] will fully offset losses due to climate change.     

胞间二氧化碳对净光合速率的影响

[目的]了解胞间二氧化碳对净光合速率的影响。[方法]以荷兰豆为试材,测定叶片不同胞间二氧化碳浓度下净光合速率的数值。[结果]不同基质配比的荷兰豆净光合速率随胞间二氧化碳浓度的增大而升高。[结论]在特定情况下,二氧化碳浓度对净光合速率影响较大。     

Leaf photosynthesis and yield components of mung bean under fully open-air elevated[CO_2]

Mung bean(Vigna radiata L.) has the potential to establish symbiosis with rhizobia,and symbiotic association of soil micro flora may facilitate the photosynthesis and plant growth response to elevated[CO_2].Mung bean was grown at either ambient CO_2 400 μmol mol~(-1) or[CO_2]((550+17) μmol mol~(-1)) under free air carbon dioxide enrichment(FACE) experimental facility in North China.Elevated[CO_2]increased net photosynthetic rate(P_n),water use efficiency(WUE) and the non-photochemical quenching(NPQ) of upper most fully-expanded leaves,but decreased stomatal conductance(G_s),intrinsic efficiency of PSII(F_v '/F_m'),quantum yield of PSII(φ_(PSll)) and proportion of open PSII reaction centers(q_p).At elevated[CO_2],the decrease of F_v'/F_m',φ_(PSII),q_p at the bloom stage were smaller than that at the pod stage.On the other hand,P_n was increased at elevated[CO_2]by 18.7 and 7.4%at full bloom(R2) and pod maturity stages(R4),respectively.From these findings,we concluded that as a legume despite greater nutrient supply to the carbon assimilation at elevated[CO_2],photosynthetic capacity of mung bean was still suppressed under elevated[CO_2]particularly at pod maturity stage but plant biomass and yield was increased by 11.6 and 14.2%,respectively.Further,these findings suggest that even under higher nutrient acquisition systems such as legumes,nutrient assimilation does not match carbon assimilation under elevated[CO_2]and leads photosynthesis down-regulation to elevated[CO_2].     

Interpenetrating As20 fullerene and Ni12 icosahedra in the onion-skin [As@Ni12@As20]3- ion

The [As@Ni12@As20]3- ion was prepared from As7(3-) and Ni(COD)2 in ethylenediamine solutions and isolated as the Bu4P+ salt (As, arsenic; Ni, nickel; COD, cyclooctadiene; Bu, butyl; P, phosphorus). The anion contains an icosahedral [Ni12(mu12-As)]3- fragment that resides at the center of an As20 dodecahedral (fullerene) cage to give an onion-skin-like [As@Ni12@As20]3- cluster with Ih point symmetry. The icosahedron and pentagonal dodecahedron are reciprocal platonic solids, and the 32 surface atoms form a dimpled geodesic sphere composed of 60 triangular faces. In the gas phase, the [As@Ni12@As20]3- ion sequentially loses all 21 As atoms to form a series of Ni12As(21-x) clusters where 0 相似文献   

生物质炭输入对土壤CO2释放影响的研究

[目的]通过对比输入生物质炭的土壤和普通土壤中土壤含碳量和CO2释放量变化,分析两者的关系,研究土壤碳固定潜力。[方法]通过在自然土壤中输入不同含量的椰壳炭,研究生物质炭输入对土壤碳截留作用的影响,探讨土壤碳截留能力与CO2释放的关系。[结果]当施炭量为1%～8%时,平均每增加1%椰壳炭量,土壤有机碳量约增加5.9 mg/g,活性有机碳量约增加0.3 mg/g。施炭量1%～5%为土壤CO2释放量增加的阶段,施炭量3%～5%时土壤CO2释放量达到最大,为549 mg/m2,之后开始降低。[结论]生物质炭施用对土壤有机碳截获及CO2释放方面有重要影响,但所受影响的趋势与施炭量和试验时间有密切关系。     

Galactose utilization in galactosemia

Cultures of human galactosemic fibroblasts without detectable transferase activity were able to convert [1-(14)C]galactose to (14)CO(2) to the same extent as normal cells, but did so at a significantly slower rate. The utilization of galactose in both normal and galactosemic cells was strongly inhibited by glucose at physiologic concentrations.     

鲤鱼上皮细胞在不同培养条件下的生长状况及与哺乳动物细胞的比较

[目的]比较鲤鱼上皮细胞在不同培养条件下的生长状况。[方法]对不同培养基、温度、胰蛋白酶浓度、CO2培养条件下鲤鱼上皮细胞（EPC）的生长状况进行观察并进行指标测定。[结果]EPC细胞在培养基M199、温度20～25℃、胰蛋白酶浓度0.05%～0.10%条件下生长较好,对CO2的需求不大。[结论]该研究结果可为鲤鱼上皮细胞最优培养条件的筛选提供依据。     

Linoleic acid hydroperoxide: impaired bacterial uptake by alveolar macrophages, a mechanism of oxidant lung injury

Exogenous linoleic acid hydroperoxide causes in vitro impairment of both bacterial uptake and the phagocytic stimulation of (14)CO(2) production from [1-(14)C]glucose in rabbit alveolar macrophages by an undefined effect on the cell membrane. This effect may be one mechanism for the defective pulmonary bacterial clearance characteristic of oxidant lung injury.     

CO_2施肥对向日葵Cu积累能力影响的研究

[目的]研究CO2施肥对向日葵积累金属能力的影响。[方法]在温室内采用盆栽试验,对不同Cu浓度土壤中生长的向日葵进行了不同浓度CO2施肥处理,观察向日葵的生物学性状及其Cu积累能力的变化。[结果]在Cu对照时,向日葵根中Cu的含量随着CO2施肥浓度的增加而显著升高;在CO2对照时,植株中的Cu含量随着土壤中Cu的增加而增加;在Cu污染土壤中,向日葵根、茎、叶中Cu含量均是在CO2800μl/L最大,且茎、叶中的Cu含量在CO2800μl/L、Cu100mg/kg(烘干土)时最高,分别为1626、2539mg/kg(干重);CO2施肥显著增加向日葵积累Cu的叶根比。[结论]CO2施肥显著增加了向日葵体内Cu的含量,植株各器官中Cu含量均高于CO2对照组。     

工业等级烟叶质量的主成分分析和聚类分析评价

[目的]对不同工业等级的烟叶进行初步质量评价.[方法]选取总糖、施木克值、糖碱比、香气量、香气质、杂气、刺激性、成熟度、身份、油分10个烟叶质量指标,以SPSS软件为工具,运用主成分分析法和Q型聚类分析对韶关市始兴县14个不同工业等级标准的烟叶质量进行评价.[结果]分析表明,按累积贡献率≥85％的标准,筛选出化学成分因子、感官质量因子、烟气成分因子共3个主成分,其对变异的累积贡献率达95.04％.不同等级的烤烟烟叶的综合评价得分差异明显,其中MO1、CF1、MF23个等级烟叶质量得分高于其他等级烟叶,而XO2、XF2、XO3 3个等级烟叶质量得分则低于其他等级烟叶.聚类分析结果表明,14个不同等级样品分为3类,其中第1类有CF2、MO2、CO1、MO3、MF2、MF3、CO2、ML2;第2类有MO1、MF1、CF1,第3类有XF2、XO3、XF3.[结论]研究可为工业等级烟叶质量评价提供参考.     

HPLC测定青海地区锁阳中没食子酸与原儿茶素的含量

[方法]建立同时测定青海地区锁阳中没食子酸和原儿茶酸含量的高效液相色谱法。[方法]采用Eclipse XDB C18柱(250.0 mm×4.6 mm,5.0μm),以甲醇0、.1%的三氟乙酸为流动相,检测波长:280 nm,流速:1 ml/min。[结果]青海地区锁阳中没食子酸含量为0.25～0.35 mg/g,原儿茶素含量为0.016 0～0.016 4 mg/g。[结论]该方法稳定,结果准确,重现性好,可为控制该药材和饮片的内在质量提供参考依据.     

开放式空气中CO2浓度增高（FACE）对常规粳稻蛋白质和氨基酸含量的影响

为了明确未来大气CO2浓度升高对水稻蛋白质营养品质的影响,2009年利用稻田开放式空气CO2浓度增高(FACE,FreeAirCO2 Enrichment)系统,以武运粳21、扬辐粳8号和武粳15为供试品种,研究大田生长期CO2浓度升高200μmol.mol-1对常规粳稻蛋白质营养品质的影响。结果表明:大气CO2浓度增加使所有供试品种精米蛋白质含量平均下降5.6%,使氨基酸、必需和非必需氨基酸总量平均分别下降7.6%、6.7%和7.9%,均达极显著水平。大气CO2浓度增加使供试品种精米必需氨基酸占氨基酸总量百分比显著增加,使非必需氨基酸占氨基酸总量百分比显著下降,但对精米中必需和非必需氨基酸的相对含量无显著影响。从氨基酸组分看,大气CO2浓度增加使供试品种精米中7种必需氨基酸和8种非必需氨基酸的含量均显著或极显著下降。CO2处理与品种对精米蛋白质含量、氨基酸总量、必需和非必需氨基酸总量以及部分氨基酸组分有一定的互作效应,武运粳21上述参数对高浓度CO2的响应大于扬辐粳8号或武粳15对应参数的响应。以上结果说明本世纪中叶大气中的CO2浓度将使粳稻蛋白质营养品质下降,不同品种下降幅度存在一定差异。