内蒙古地带性针茅植物对CO2和气候变化的适应性研究进展

收集了1992—2013年关于模拟CO2浓度升高及气候变化(温度升高、降水变化)对内蒙古地带性草原群落的5个建群种针茅植物(贝加尔针茅、本氏针茅、大针茅、克氏针茅、短花针茅)影响的实验研究结果表明,模拟CO2浓度升高、增温和增雨将提高针茅植物的光合作用和株高生长,但CO2处理时间延长会导致光合适应;温度和降雨变化将改变针茅植物的物候进程,但物种之间反应有差异;CO2浓度升高有助于针茅植物生物量增加,增温和干旱则相反,CO2浓度升高对干旱的影响具有补偿作用;干旱和涝渍胁迫将提高针茅植物植株C/N,CO2浓度升高将加剧水分胁迫下针茅植物植株C/N的增加效应,导致牧草品质下降。由于当前在适应性指标、针茅植物对气候变化协同作用的适应机理及其敏感性研究等方面存在的不足,导致目前无法全面比较各针茅植物对CO2和温度、降水变化的响应差异及其敏感性,因而无法预测未来在全球变化背景下,这几种针茅植物的动态变化及其在地理分布上的迁移替代规律。为科学应对气候变化,未来应加强内蒙古地带性针茅植物的适应性指标、针茅植物对多因子协同作用的适应机理及敏感性研究。     

CO2浓度升高和不同灌溉量对东北玉米光合特性及产量的影响

CO2和水分是植物光合作用的重要底物,大气CO2浓度升高或水分变化影响植物光合作用。玉米是重要的C4植物,目前已成为我国第一大作物。我国东北地区的玉米产量占全国玉米产量的1/3左右,对确保国家的粮食安全具有重要作用。但是,关于CO2浓度升高或水分变化共同作用对东北玉米的光合速率、水分利用效率和产量影响的研究甚少。基于开顶式生长箱(OTCs),模拟研究了CO2浓度变化(390、450、550μmol/mol)和降水变化(0、+15%(以试验地锦州1981—2010年6、7、8月月平均降水量88.7,153.9 mm和139.8 mm为基准))共同作用对玉米光合特性及产量的影响。以玉米品种丹玉39为材料,利用直角双曲线修正模型对6个处理(C550W+15%、C550W0、C450W+15%、C450W0、C390W+15%和C390W0)的光响应曲线进行了拟合。结果表明:在CO2浓度升高和灌溉的共同作用下,玉米叶片净光合速率(Pn)升高,且灌溉作用大于高CO2浓度作用;而蒸腾速率(Tr)则下降,使水分利用效率(WUE)升高。CO2浓度升高使气孔导度(Gs)降低,灌溉则使之升高,但灌溉的作用小于高CO2浓度作用;胞间CO2浓度(Ci)随CO2浓度增加而升高,灌溉对其影响不明显。高CO2浓度和灌溉共同作用下光响应参数差异明显。CO2浓度升高增加了最大净光合速率(Pnmax)和光饱和点(LSP),灌溉亦然;CO2浓度升高使得光补偿点(LCP)、光补偿点量子效率(φc)和暗呼吸速率(Rd)的灌溉处理和自然降水处理的差距变小。390、450、550μmol/mol CO2浓度下的灌溉处理与自然降水处理相比,叶面积分别增加了11.56%、3.31%和0.45%,干物质积累量分别增加了14.69%、8.09%和1.01%,最终使产量分别增加了10.47%、12.07%和8.96%。可见,在高CO2浓度下,适量的灌溉对玉米的整个光合作用过程起到了促进作用,最终表现为籽粒产量的增加。为研究者评估气候变化对中国东北地区作物光合能力和产量的影响及决策者调整适应气候变化措施方面提供依据。     

杨柴对高CO2浓度和土壤干旱胁迫的响应

毛乌素优势植物杨柴 (HedysarummongolicumTurcz.)对高CO2 浓度和土壤干旱胁迫响应的研究结果表明 :干旱胁迫可使杨柴根系伸长 ,根生物量、地径、主茎高和茎生物量下降 ;高CO2 浓度使杨柴根和茎生物量明显增加 ,CO2 的“施肥效应”显著 ,干旱使CO2 的“施肥效应”减弱。同时 ,土壤干旱胁迫使杨柴的根 /冠比增加 ,说明在土壤干旱胁迫情况下根的生长比地上部分 (茎 )的生长更活跃 ,有利于提高杨柴在干旱沙漠地区的固沙作用 ;CO2 浓度升高和土壤干旱胁迫均使杨柴叶片的水势下降 ,叶片水势的下降使叶片细胞对水分的束缚力增强 ,从而减少植物蒸腾耗水 ,有利于提高水资源的利用效率     

CO_2浓度倍增对干旱胁迫下黄瓜幼苗膜脂过氧化及抗氧化系统的影响

为了探明CO2浓度倍增对干旱胁迫下黄瓜幼苗氧化损伤的缓解机理,为未来大气CO2浓度升高或温室CO2施肥以及干旱、半干旱地区水分亏缺等逆境胁迫下黄瓜的优质高效栽培提供理论依据和技术参数,以温室专用黄瓜品种津优1号(Cucumissativus L.var.Jinyou No.1)为试材,采用裂区设计,主区因素为CO2浓度处理,设2个CO2浓度水平:大气CO2浓度(≈380μmol/mol,表示为Ambient[CO2])和倍增CO2浓度((760±20)μmol/mol,表示为Doubled[CO2]);裂区因素为水分处理,用PEG6000模拟根际干旱胁迫,设3个水分处理水平:对照(营养液,表示为C)、中度干旱胁迫(含5%PEG6000的营养液,相当于水势ψw=-0.05MPa,表示为M)和重度干旱胁迫(含10%PEG6000的营养液,相当于水势ψw=-0.15MPa,表示为S),研究了CO2浓度倍增对干旱胁迫条件下黄瓜幼苗叶片渗透调节物质含量、膜脂过氧化及抗氧化系统的影响,结果表明:(1)干旱胁迫导致黄瓜幼苗活性氧积累,质膜透性增大,丙二醛含量升高,同时幼苗叶片脯氨酸、可溶性蛋白质和可溶性总糖含量显著增加,抗氧化酶活性(SOD、POD、CAT、APX和GR)显著提高,抗坏血酸(AsA)和还原型谷胱甘肽(GSH)含量显著升高;(2)CO2浓度倍增不仅有利于促进干旱胁迫条件下黄瓜叶片渗透调节物质的积累,而且能够促进干旱胁迫条件下黄瓜叶片抗氧化酶(SOD、POD、CAT、APX和GR)活性的表达,减轻干旱胁迫下活性氧的积累,使膜脂过氧化程度下降,质膜相对透性降低,丙二醛含量减少,对防止植物的氧化损伤具有一定的保护作用。综上所述,推测温室CO2施肥或未来CO2浓度升高可在一定程度上增强黄瓜幼苗的抗旱性和缓解干旱胁迫的负效应。     

干旱胁迫下CO2浓度升高对转StAPX番茄植株耐旱能力的影响

在干旱胁迫伴随大气CO2浓度以及升高的CO2浓度（加倍）条件下,以过量表达番茄类囊体膜抗坏血酸过氧化物酶基因（StAPX）的转基因番茄为试材,探明干旱胁迫TCO2浓度升高对转基因及其野生型番茄植株清除活性氧及耐旱能力的影响。结果表明：升高的CO2浓度明显增加了干旱胁迫下植物的光合水平;升高的CO2浓度明显降低了干旱导致的植物体内H2O2．和O2的积累,影响了干旱胁迫下番茄植株的水．水循环系统的活性氧清除酶活性和小分子抗氧化物质含量;干旱胁迫下即使伴随升高的CO2浓度,测试番茄植株体内的渗透调节物质含量变化也不太明显;升高的CO2浓度明显降低了干旱胁迫下的植物细胞膜伤害程度;干旱胁迫下,升高的CO2浓度对转基因番茄株系比对野生型植株的影响更加明显。结果证明干旱逆境下,升高的CO2浓度能够在一定程度上进一步提高转基因番茄植株的耐旱性。     

CO2浓度升高对大豆干旱胁迫的缓解效应

CO₂浓度升高和干旱带来的气候变化势必对大豆的生长造成影响。目前,CO₂浓度升高对干旱胁迫下大豆生理生化的影响研究较少。本试验研究了不同CO₂浓度(400、600 μmol·mol^–1)和水分处理下(正常水分:叶片相对含水量为83%～90%;干旱:叶片相对含水量为64%～70%)大豆开花期的光合能力、光合色素积累、抗氧化水平、渗透调节物质、激素水平、信号转导酶和基因表达量的变化。结果表明: 干旱胁迫下CO₂浓度升高显著提高了大豆叶片蒸腾速率、水分利用效率和净光合速率,但降低了叶绿素b含量。CO₂浓度升高显著增加了干旱胁迫下叶片过氧化物酶活性和脱落酸含量,显著降低了脯氨酸含量,对可溶性糖含量没有显著影响。干旱胁迫下CO₂浓度升高显著增加了钙依赖蛋白激酶含量和谷胱甘肽-S-转移酶活性,并且其基因表达量均显著上调;显著降低了丝裂原活化蛋白激酶和热休克蛋白含量,并下调了其基因表达量。研究结果将有助于了解气候变化对大豆生长和生理生化的影响,为应对未来气候变化下大豆生产采取必要措施。     

CO2浓度倍增与干旱胁迫对油松（Pinus tabulaeformis）相对分枝级水力结构的影响

在密闭式生长箱内经过13个月高CO2浓度培养的5年生油松(Pinus tabulaeformis)为实验对象,采用改良冲洗法研究了CO2浓度倍增(720μmolmol-1)与干旱胁迫交互作用对油松相对分枝级水力结构参数的影响.通过测定油松不同分枝级的水力结构参数分别在720μmolmol-1 CO2和380μmolmol-1 CO2(大气现有CO2浓度)浓度下随着干旱胁迫的变化,得出不同分枝级的导水率(Kh)、比导率(Ks)和胡伯尔值(Hv)在2个CO2浓度下均随着干旱胁迫的增加而逐渐下降,叶比导率(Lsc)在720μmolmol-1CO2浓度下随着干旱胁迫的增加非线性变化(0级>2级>1级)不同于380μmolmol-1 CO2(0级>1级>2级).同期干旱胁迫条件下,720μmolmol-1CO2浓度下的Kh、Ks、Lsc 和Hv均大于380μmolmol-1 CO2且差异显著.根据整株苗木的水势将苗木的水分状况分为4个梯度,在正常水分(-0.45～-0.65MPa)、轻度干旱(-1.15～-0.75MPa)和中度干旱(-1.95～-1.35MPa)胁迫时,3个分枝级均在720μmolmol-1CO2条件下的Kh和Ks较380μmolmol-1 CO2增加,说明交互作用能提高导水能力,同时加快水分运输效率.在重度干旱(＜-2.80MPa)胁迫时Kh比380μmolmol-1 CO2增加,而Ks比380μmolmol-1 CO2减小,即交互作用提高了水分运输的安全性,却减少了有效性.     

施氮深度和水分胁迫对藜麦幼苗生理及产量的影响

为了探讨藜麦应对施肥深度和水分胁迫的响应,该文以藜麦(Chenopodium quinoa)为材料,在盆栽条件下,设置3种施氮处理[D1(控释尿素施在0～8 cm深度)、D2(控释尿素施在8～16 cm深度)、D3(控释尿素施在16～24 cm深度)]和3种水分处理[W1(正常供水)、W2(中度干旱)、W3(重度干旱)],分析施氮深度和水分胁迫对藜麦幼苗生理及产量的影响。结果表明:(1)相同水分条件下,随着施肥深度的增加,藜麦生长指标(株高、茎粗、叶面积、地上部生物量、主根长、根系表面积、根系体积)、生理指标 [超氧化物歧化酶(SOD)活性、过氧化物酶(POD)活性、过氧化氢酶(CAT)活性、可溶性糖含量、可溶性蛋白含量、叶绿素总量]和产量指标呈先升高后降低趋势。D2处理(适当的深施氮肥)均高于D1处理(浅层施氮)和D3处理(底层施氮)。(2)相同施氮深度条件下,随着干旱胁迫程度的增加,藜麦生长指标和产量指标呈逐渐降低的趋势,生理指标均呈先升高后降低的趋势。说明藜麦幼苗对水分需求明显,可通过增加抗氧化酶活性和渗透调节物质适应一定程度的干旱,生产实践中应注意苗期水分的供应,以促进生育后期产量的形成。综上可知,适宜的水氮管理(D2W1)可以促进藜麦的生长及生理特性,增强藜麦的抗旱能力,提高藜麦的产量。该研究结果为进一步研究藜麦的水肥管理、高产栽培提供参考。     

干旱胁迫和CO2浓度升高条件下白羊草的光合特征

采用盆栽控制试验,研究了黄土丘陵区乡土种白羊草在不同水分水平(80％ FC和40％ FC)和CO2浓度(375和750 μmol·m-2·s-1)处理下的光合生理变化特征.结果表明:干旱胁迫使白羊草的最大净光合速率(Pnmax)、表观量子效率(AQE)、气孔导度(gs)、蒸腾速率(Tt)、最大光化学效率(Fv/Fm)、潜在光化学效率(Fv/Fo)和光合色素含量降低,丙二醛(MDA)和脯氨酸(Pro)含量升高.水分充足条件下,与正常大气CO2浓度相比,大气CO2浓度倍增下白羊草的PnmaxMDA和Pro含量无显著差异.干旱胁迫下,CO2浓度升高提高了白羊草的最大荧光(Fm)、Fv/Fm、Fv/Fo、叶绿素含量和AQE,Pnmax比正常CO2浓度下高23.3％,差异达到显著水平,而MDA和Pro含量均显著降低.CO2浓度升高对干旱胁迫引起的白羊草光合能力下降有一定的补偿作用,减轻了干旱胁迫对白羊草的伤害.     

干旱胁迫和CO2浓度升高条件下白羊草的光合特征

采用盆栽控制试验,研究了黄土丘陵区乡土种白羊草在不同水分水平(80%FC和40%FC)和CO₂浓度(375和750 μmol·m^-2·s^-1) 处理下的光合生理变化特征.结果表明： 干旱胁迫使白羊草的最大净光合速率(P_nmax)、表观量子效率(AQE)、气孔导度(g_s)、蒸腾速率(T_r)、最大光化学效率(F_v/F_m)、潜在光化学效率(F_v/F_o)和光合色素含量降低,丙二醛(MDA)和脯氨酸(Pro)含量升高.水分充足条件下,与正常大气CO₂浓度相比,大气CO₂浓度倍增下白羊草的P_{n max}、MDA和Pro含量无显著差异.干旱胁迫下,CO₂浓度升高提高了白羊草的最大荧光(F_m)、F_v/F_m、F_v/F_o、叶绿素含量和AQE, P_nmax比正常CO₂浓度下高23.3%,差异达到显著水平,而MDA和Pro含量均显著降低.CO₂浓度升高对干旱胁迫引起的白羊草光合能力下降有一定的补偿作用,减轻了干旱胁迫对白羊草的伤害.     

Unambiguous through-bond sugar-to-base correlations for purines in 13C, 15N-labeled nucleic acids: The HsCsNb,HsCs(N)bCb,and HbNbCb experiments

Summary A set of three 3D (¹H, ¹³C, ¹⁵N) triple-resonance correlation experiments has been designed to provide H1-H8 intraresidue sugar-to-base correlations in purines in an unambiguous and efficient manner. Together, the H_sC_sN_b, H_sC_s(N)_bC_b, and H_bN_bC_b experiments correlate the H1 sugar proton to the H8 proton of the attached base by means of the {H1, C1, N9, C8, H8} heteronuclear scalar coupling network. The assignment strategy presented here allows for unambiguous H1-H8 intraresidue correlations, provided that no two purines have both the same H1 and C1 chemical shifts and the same C8 and N9 chemical shifts. These experiments have yielded H1-H8 intraresidue sugar-to-base correlations for all five guanosines in the [¹³C, ¹⁵N] isotopically labeled RNA duplex r(GGCGCUUGCGUC)₂.     

Crystal structure of the ternary FimC-FimF(t)-FimD(N) complex indicates conserved pilus chaperone-subunit complex recognition by the usher FimD

Type 1 pili, anchored to the outer membrane protein FimD, enable uropathogenic Escherichia coli to attach to host cells. During pilus biogenesis, the N-terminal periplasmic domain of FimD (FimD(N)) binds complexes between the chaperone FimC and pilus subunits via its partly disordered N-terminal segment, as recently shown for the FimC-FimH(P)-FimD(N) ternary complex. We report the structure of a new ternary complex (FimC-FimF(t)-FimD(N)) with the subunit FimF(t) instead of FimH(p). FimD(N) recognizes FimC-FimF(t) and FimC-FimH(P) very similarly, predominantly through hydrophobic interactions. The conserved binding mode at a "hot spot" on the chaperone surface could guide the design of pilus assembly inhibitors.     

μ- and μ4-η coordination of A2H2 (A = C, Si, Ge, Sn and Pb) ligands with transition metals

The heavier analogs of C₂H₂ have been studied at the B3LYP level for their μ and μ₄-η² coordination properties with the transition metals. Based on known alkyne compounds, transition metal fragments [W₂(μ-NH)(Cp)₂(Cl)₂] and [Fe₄(CO)₁₂] have been chosen. The SBKJC relativistic effective core potentials and their associated basis sets were used on W, Fe, Sn and Pb, and the 6-31G(d) basis set was used on all other elements. All the complexes of Si₂H₂, Ge₂H₂, Sn₂H₂ and Pb₂H₂ are found to be local minima. The trans-twist nature of the ligand A₂H₂ (A = Si-Pb) is large in μ-coordinated complexes of W, and it is very small in μ₄-η² coordinated complexes of Fe. The electronic structure of these complexes was investigated using fragment molecular orbital method (FMO).     

Introduction: A Close Look at the Vacuolar ATPase

The vacuolar ATPases (V-type ATPases) are a family of ATP-dependent ion pumps and found in two principal locations, in endomembranes and in plasma membranes. This family of ATPases is responsible for acidification of intracellulare compartments and, in certain cases, ion transport across the plasma membrane of eucaryotic cells. V-ATPases are composed of two distinct domains: a catalytic V₁ sector, in which ATP hydrolysis takes place, and the membrane-embedded sector, V₀, which functions in ion conduction. In the past decade impressive progress has been made in elucidating the properties structure, function and moleculare biology. These knowledge sheds light also on the evolution of V-ATPases and their related families of A-(A₁A₀-ATPase) and F-type (F₁F₀-ATPases)ATPases.     

Acetylcholinesterase/Butyrylcholinesterase inhibition activity of some new carbacylamidophosphate deriviatives

Eight newly synthesized carbacylamidophosphates with the general formula RC(O)NHP(O)Cl₂ with R = pCl–C₆H₄ 1a, pBr–C₆H₄ 2a, C₆H₅ 3a, and pMe–C₆H₄ 4a and RC(O)NHP(O)(NC₄H₈O)₂ R = pCl–C₆H₄ 1b, pBr–C₆H₄ 2b, C₆H₅ 3b, pMe–C₆H₄ 4b, were selected to compare the inhibition kinetic parameters, IC₅₀, K_i, k_p and K_D, on human erythrocyte acetylcholinesterase (hAChE) and bovine serum butyrylcholinesterase (BuChE), Also, the in vivo inhibition potency of compound 2a, 2b and 3a, were studied. The data demonstrates that compound 2a and compound 2b are the potent sensitive as AChE and BuChE inhibitors respectively, and the inhibition of hAChE is about 10-fold greater than that of BuChE.     

Antibacterial properties of recombinant human non-pancreatic secretory phospholipase A2

Human non-pancreatic secretory phospholipase A₂ (hnpsPLA₂) is a group IIA phospholipase A₂ which plays an important role in the innate immune response. This enzyme was found to exhibit bactericidal activity toward Gram-positive bacteria, but not Gram-negative ones. Though native hnpsPLA₂ is active over a broad pH range, it is only highly active at alkaline conditions with the optimum activity pH of about 8.5. In order to make it highly active at neutral pH, we have obtained two hnpsPLA₂ mutants, Glu89Lys and Arg100Glu that work better at neutral pH in a previous study. In the present study, we tested the bactericidal effects of the native hnpsPLA₂ and the two mutants. Both native hnpsPLA₂ and the two mutants exhibit bactericidal activity toward Gram-positive bacteria. Furthermore, they can also kill Escherichia coli, a Gram-negative bacterium. The two mutants showed better bactericidal activity for E. coli at neutral pH than the native enzyme, which is consistent with the enzyme activities. As hnpsPLA₂ is highly stable and biocompatible, it may provide a promising therapy for bacteria infection treatment or other bactericidal applications.     

Earthworm effects on gaseous emissions during vermifiltration of pig fresh slurry

Treatment of liquid manure can result in the production of ammonia, nitrous oxide and methane. Earthworms mix and transform nitrogen and carbon without consuming additional energy. The objective of this paper is to analyse whether earthworms modify the emissions of NH₃, N₂O, CH₄ and CO₂ during vermifiltration of pig slurry.The experiment used mesocosms of around 50 L, made from a vermifilter treating the diluted manure of a swine house. Three levels of slurry were added to the mesocosms, with or without earthworms, during one month, in triplicate. Earthworm abundance and gas emissions were measured three and five times, respectively.There was a decrease in emissions of ammonia and nitrous oxide and a sink of methane in treatments with earthworms. We suggest that earthworm abundance can be used as a bioindicator of low energy input, and low greenhouse gas and ammonia output in systems using fresh slurry with water recycling.     

Crystal structure of the archaeal A1Ao ATP synthase subunit B from Methanosarcina mazei Gö1: Implications of nucleotide-binding differences in the major A1Ao subunits A and B

The A1Ao ATP synthase from archaea represents a class of chimeric ATPases/synthases, whose function and general structural design share characteristics both with vacuolar V1Vo ATPases and with F1Fo ATP synthases. The primary sequences of the two large polypeptides A and B, from the catalytic part, are closely related to the eukaryotic V1Vo ATPases. The chimeric nature of the A1Ao ATP synthase from the archaeon Methanosarcina mazei G?1 was investigated in terms of nucleotide interaction. Here, we demonstrate the ability of the overexpressed A and B subunits to bind ADP and ATP by photoaffinity labeling. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry was used to map the peptide of subunit B involved in nucleotide interaction. Nucleotide affinities in both subunits were determined by fluorescence correlation spectroscopy, indicating a weaker binding of nucleotide analogues to subunit B than to A. In addition, the nucleotide-free crystal structure of subunit B is presented at 1.5 A resolution, providing the first view of the so-called non-catalytic subunit of the A1Ao ATP synthase. Superposition of the A-ATP synthase non-catalytic B subunit and the F-ATP synthase non-catalytic alpha subunit provides new insights into the similarities and differences of these nucleotide-binding ATPase subunits in particular, and into nucleotide binding in general. The arrangement of subunit B within the intact A1Ao ATP synthase is presented.     

Assessing the Impact of Advected African Dust on Air Quality and Health in the Eastern United States

Large quantities of African dust are carried into the southeastern United States each summer with concentrations typically in the range of 10 to 100?µg m^?3. Because approximately one-third to one-half of the dust mass is in the size range under 2.5?µm diameter, the advection of African dust has implications for the EPA's newly implemented standard for PM_2.5 particulate matter and for the assessment of human health effects. It will be difficult to assess the impact of African dust events on air quality because they occur during the summer (maximum in July) when photochemical pollution events are frequent and intense in the eastern United States. Indeed, the presence of dust could affect the evolution of photochemical dust events. In order to assess the role of African dust in air quality in the United States, it will be necessary to develop a set of diagnostic indicators; it appears that dust mineralogy and elemental composition might be useful for this purpose. Various satellite products can be used to characterize the spatial coverage of dust events and, when coupled with meteorological tools, to predict impact regions.