增温对川西北亚高山高寒草甸植物群落碳、氮含量的影响

采用开顶式生长室（OTC）模拟增温实验,研究了川西北亚高山草甸植物群落碳、氮含量对温度升高的响应。由于OTC的增温作用,在整个生长季内,地温（15 cm）、地表温度和气温(30 cm)的平均值在OTC内比对照样地分别高0.28、0.46和1.4℃,OTC内土壤相对含水量也明显减少,低于对照样地5.49%。受增温及土壤含水量减少的影响,一年后,植物群落的生物量积累和碳、氮含量发生了明显的改变。除10月份OTC内地上鲜体生物量略高于对照样地外,OTC内地上鲜体生物量和根系生物量与对照样地相比,都出现了不同程度的减少;OTC内植物群落地上活体的碳浓度在整个生长季高于对照样地,而氮浓度低于对照样地;OTC内植物群落地下活根的碳浓度在整个生长季高于对照样地,并且在8月份统计检验显著,而氮浓度却低于对照样地;OTC内植物碳库在整个生长季较对照样地有不同程度的增加,增幅范围为0.90%～5.65%,而OTC内植物氮库较对照样地有不同程度的减少,减幅范围0.40%～1.28%。     

短期增温对青藏高原高寒草甸植物群落结构和生物量的影响

采用增温棚模拟增温的方法,对比研究了青藏高原腹地典型高寒草甸和沼泽草甸在两种增温梯度条件下植物群落结构及植物生长对温度升高的初期响应。由于开顶式生长室(OTC)的增温作用,在整个生长季内,沼泽草甸月平均气温分别较对照提高2.98℃ (OTC1)和 5.52℃((OTC2),20cm处土壤水分分别减少了2.45%(OTC1)和3.44%(OTC2);高寒草甸月平均气温分别比对照升高了2.59℃(OTC1)和 5.16℃ (OTC2)。20cm处土壤水分分别减少了1.83%(OTC1)和7.71%(OTC2)。受温度升高及土壤含水量减少的影响,模拟增温2个生长季后,与对照样地相比,群落种群高度、密度、盖度、频度和重要值发生变化,群落结构也发生一定变化。增温处理使高寒草甸禾草和莎草盖度减少,杂草盖度增加,而使沼泽草甸中禾草和莎草盖度增加,杂草盖度减少。增温后,两种草甸总生物量均增加,但大幅度的增温条件抑制了高寒草甸的这种促进作用,而促进了沼泽草甸的这种促进作用。两种草甸的地下生物量主要分布在土壤表层,模拟增温使得高寒草甸的生物量分配格局向深层转移,但不明显;而使沼泽草甸生物量明显的趋向深层土壤中转移。     

模拟增温对青藏高原高寒草甸根系生物量的影响

在青藏高原高寒草甸布设模拟增温实验样地,采用土钻法于2012—2013年植被生长季获取5个土层的根系生物量,探讨增温处理下根系生物量在生长季不同月份、不同土壤深度的变化趋势及其与相应土层土壤水分、温度的关系。结果表明:(1)根系生物量在2012年随月份呈增加趋势,其中7—9月较大,其平均值在对照、增温处理下分别为3810.88 g/m~2和4468.08 g/m~2;在2013年随月份呈减小趋势,其中5—6月较大,其平均值在对照、增温处理下分别为4175.39 g/m~2和4141.6 g/m~2。增温处理下的总根系生物量高出对照处理293.97 g/m~2,而各月份总根系生物量在处理间的差值均未达到显著水平。表明在增温处理下根系生物量略有增加,但在生长季不同月份其增加的程度不同,致使年际间的增幅出现差异。(2)根系生物量主要分布在0—10 cm深度,所占百分比为50.61%。在增温处理下,0—10 cm深度的根系生物量减少,减幅为8.38%;10—50 cm深度的根系生物量增加,增幅为2.1%。相对于对照处理,增温处理下0—30 cm深度的根系生物量向深层增加,30—50 cm深度的根系生物量增加趋势略有减缓。可见,在增温处理下根系生物量的增幅趋向于土壤深层。(3)根系生物量与土壤水分呈极显著的递减关系,在增温处理下线性关系减弱;与土壤温度呈极显著的递增关系,在增温处理下线性关系增强。表明土壤水分、温度都可极显著影响根系生物量,但在增温处理下土壤温度对根系生物量的影响较土壤水分更为敏感而迅速。     

短期增温和增加降水对内蒙古荒漠草原土壤呼吸的影响

利用红外辐射增温装置模拟短期持续增温和降水增加交互作用对内蒙古荒漠草原土壤呼吸作用的影响, 结果表明: 土壤含水量对月土壤呼吸的影响显著大于土壤温度增加的影响, 生长旺季的月土壤呼吸显著大于生长末季; 土壤温度和水分增加都显著影响日土壤呼吸, 但二者的交互作用对土壤呼吸无显著影响。荒漠草原7‒8月平均土壤呼吸速率为1.35 μmol CO₂·m ^-2·s ^-1, 7月份为2.08 μmol CO₂·m ^-2·s ^-1, 8月份为0.63 μmol CO₂·m ^-2·s ^-1。土壤呼吸与地下各层根系生物量呈幂函数关系, 0‒10 cm土层的根系生物量对土壤呼吸的解释率(79.2%)明显高于10‒20 cm土层的解释率(31.6%)。0-10 cm土层的根系生物量是根系生物量的主体, 根系生物量对土壤呼吸的影响具有层次性。在未来全球变暖和降水格局变化的情景下, 荒漠草原土壤水分含量是影响生物量的主导环境因子, 而根系生物量的差异是造成土壤呼吸异质性的主要生物因素, 土壤含水量可通过影响根系生物量控制土壤呼吸的异质性。     

采伐干扰对林下草本根系生物量与土壤环境异质性关系的影响

结合统计学和地统计学的理论,探讨了采伐干扰对华北落叶松林下草本根系生物量空间异质性及与林下土壤含水量、全氮、硝态氮、铵态氮、pH及华北落叶松细根生物量空间异质性的关联性。结果表明,采伐干扰样地草本根系生物量为 31.17 g/m²,明显小于未干扰样地(72.01 g/m²);采伐干扰导致草本根系生物量更多地向表层积聚。0~10 cm土层,采伐干扰样地草本根系生物量的空间异质性(C₀+C=31330.0)和空间自相关性(C/C₀+C=92.5%)明显增强,表现出较强的空间依赖性。采伐干扰后,土壤水分、全氮、硝态氮和铵态氮对草本根系生物量的相关性增强;未采伐干扰样地华北落叶松细根生物量与草本根系生物量的相关性较强。     

短期增温和降水减少对半干旱沙质草地群落特征的影响

【目的】为探究短期增温和降水减少对沙质草地植物群落物种多样性、功能性状及生产力的影响,进一步揭示沙质草地植物群落特征对气候变化的响应。【方法】以科尔沁沙质草地植物群落为研究对象,利用开顶式生长室(OTC)模拟增温,研究降水减少0%、20%、40%和60%与增温的交互作用对沙质草地群落组成、物种多样性和功能性状的影响及群落特征与环境因子关系。【结果】结果显示:（1）短期增温和降水减少使沙质草地植物群落组成和物种优势度发生变化,其中优势物种猪毛蒿和达乌里胡枝子在短期增温和降水减少处理下均明显降低,短期增温和降水减少均显著降低了植物群落盖度和地上生物量。（2）短期增温显著降低了Margalef丰富度指数、Simpson指数、Shannon多样性指数和Pielou均匀度指数,短期降水减少对沙质草地供试4种物种多样性指标均无显著影响。（3）短期增温显著提高了植物群落高度和叶干物质含量,显著降低叶厚度,短期降水减少显著提高了叶干物质含量和叶厚度,显著降低了植株高度和比叶面积。（4）短期增温是影响沙质草地物种多样性和功能性状的主要环境因素。【结论】综上可知,短期增温和降水减少改变了沙质草地群落特征,温度是影响沙质草地群落特征的主要环境因子。     

六盘山林区几种土地利用方式对土壤有机碳矿化影响的比较

 应用土壤培养法,比较分析了六盘山林区天然次生林（杂灌林、山杨（Populus davidanda）和辽东栎（Quercus liaotungensis）林）、农田、草地和人工林（13 a、18 a和25 a华北落叶松（Larix principis-rupprechtii））土壤在30℃和60%田间饱和含水量条件下培养180 d有机碳矿化速率的差异（以180 d累计释放的CO2-C计）。结果显示：农田和草地土壤碳矿化释放的CO2-C含量（180 d释放的gCO2-C·kg-1干土）分别比天然次生林低65%和23%,差异主要在0～40土层;人工林比农田和草地分别高155%和 17%,差异主要在0～70 cm土层。农田土壤碳矿化释放的CO2-C分配比例（即180 d释放CO2-C/土壤 C）比天然次生林平均低12%,草地比天然次生林平均高18%,差异主要在0～40 cm土层;人工林比农田平均高29%,草地比人工林平均高9%,差异主要在0～50 cm土层。不同土地利用方式土壤碳矿化释放的CO2-C含量的差异比其分配比例的差异大。土壤碳矿化释放的CO2-C含量和分配比例总体上都随土层加深而递减。分配比例随土层加深而递减的幅度方面,不同土地利用方式间的差异不大;含量随土层加深而递减的幅度方面,天然次生林和人工林比农田和草地中大;随土层递减的幅度方面,土壤碳矿化释放的CO2-C含量比其分配比例大。这主要由不同土地利用方式土壤碳输入和稳定性等差异所致。结果说明土壤碳矿化速率随天然次生林变成农田或草地而下降,随在农田或草地上造林而增加, 矿化速率变化幅度比分配比例的变化幅度大。另外,土地利用变化也使不同土层土壤碳矿化速率和分配比例差异改变,其中速率改变的幅度比分配比例改变的幅度大。     

大气增温对杉木幼树根系生物量的影响

为揭示亚热带杉木人工林地下生物量对全球变暖的响应,本研究以杉木幼树为研究对象,在福建三明森林生态系统国家野外科学观测研究站利用开顶式(OTC)大气增温模拟气候变暖,研究增温对杉木幼树根系生物量的空间分布和不同径级分配的影响。结果表明：增温处理后总根系生物量、总细根生物量及总粗根生物量较对照均无显著差异;与对照相比,增温处理显著降低20～50 cm土层的细根生物量占比与0～10 cm土层的粗根生物量占比,但显著提高20～50 cm土层的粗根生物量占比;其余土层细根生物量和粗根生物量较对照均无显著差异;与对照相比,增温处理后0～2、2～5、5～10、10～20和>20 mm径级根系生物量均无显著变化。因此,增温处理下杉木幼树通过降低表层粗根生物量的占比,提高深层粗根生物量的占比以固定和支撑杉木生长,同时通过降低深层细根生物量的占比来维持表层细根生物量以保证水分和养分的吸收;大气增温影响根系生物量的垂直分布和不同径级的分配,在一定程度上影响地下碳分配,可能导致碳循环过程发生改变。     

放牧对贝加尔针茅草原植被根系分布和土壤理化特征的影响

以内蒙古贝加尔针茅草原为研究对象,分析了放牧对植被根系分布特征的影响及其与土壤理化性状的相互关系。结果表明:放牧导致植被根系分布发生显著变化;0～10cm土层根系生物量占0～40cm根系总生物量的65.9%～82.6%,直径≥2mm根系和直径1mm的根系对放牧影响较为敏感;植被根系分布与土壤容重、含水量、全氮、全磷、有机碳含量以及阳离子交换量有一定程度的相关性,放牧主要通过改变土壤理化特征影响不同径级根系生物量的分布,同时各径级根系分布特征对土壤理化性状有一定的反馈作用。     

藏北高山嵩草草甸群落特征及生产力对模拟增温幅度的响应

青藏高原气候严酷,陆地表层生态系统脆弱,其高寒植物群落特征及生态系统生产力对气候变化的响应极其敏感。利用开顶箱(OTCs,Open Top Chambers)式装置在藏北高山嵩草(Kobresia pygmaea)草甸设置不同增温梯度实验(W1、W2、W3、W4),探究增温对高寒草甸植物群落特征及地上生产力的影响。研究结果表明:1)与对照样地相比,增温减少了植物群落总盖度(2015年,W1、W2、W3、W4分别显著减少了28%、23%、59%、60%; 2016年,W4显著减少了83%)和高山嵩草盖度(2015年,W1、W2、W3、W4分别显著减少了26%、33%、681%、64%; 2016年,W4显著减少了85%),而低幅度增温(W1、W2)对委陵菜属植物盖度无显著影响,高幅度增温(W3、W4)显著减少了委陵菜属植物盖度(2015年,W3、W4分别显著减少了58%和60%;2016年,W4显著减少了71%); 2)对整个植物群落而言,增温幅度较低时,增温对群落的生长和生物量的积累有促进作用,当温度升高超过一定程度,这种促进作用会逐渐减弱甚至变成抑制作用(2015年,W4显著减少了地上生物量69%; 2016年,W4显著减少了地上生物量82%); 3)高山嵩草盖度和其他物种总盖度存在显著的年际差异,而委陵菜属植物盖度无明显的年际变化。研究结果预示着,一定程度的升温会促进高寒草甸植物群落的生长,但温度升高超过一定幅度时,会导致草地生产力下降,草地退化加剧,同时当地群落中委陵菜属植物在全球变化背景下相对稳定,这类物种在未来气候变暖的背景下可能具有更强的竞争力。     

六种藓类植物茎的比较解剖学研究

通过对6种藓类植物,即褶叶青藓(Brachythecium salebrosum(Web.et Mohr.)B.S.G.)、湿地匐灯藓(Plagiomnium acutum(Lindb.)Kop.)、侧枝匐灯藓(Plagiomnium maximoviczii(Lindb.)Kop.)、大凤尾藓(Fissidensnobilis Griff.)、大羽藓(Thuidium cymbifolium(Doz.et Molk.)B.S.G.)和大灰藓(Hypnum plumaeforme Wils.)嫩茎和老茎的石蜡切片和显微观察发现,同一藓类植株的嫩茎和老茎,茎结构稳定,不同种藓类植物茎横切面具有不同特征.植物体茎横切面形状、表层细胞的层数、细胞大小和细胞壁厚薄、皮层细胞大小和形状、中轴的有无以及比例等特征可以作为藓类植物的分科分类依据之一.     

Photoregulation of seed germination of wild-type and of an aurea-mutant of tomato

Seed germination of an aurea mutant of tomato ( Lycopersicon esculentum Mill.) is promoted by continuous irradiation with red, far-red or long-wavelength far-red (758 nm) light as well as by cyclic irradiations (5 min red or 5 min far-red/25 min darkness). Far-red light applied immediately after each red does not change the germination behaviour. Seed germination of the isogenic wild-type, cv. UC-105, is promoted by continuous and cyclic red light while it is inhibited by continuous and cyclic far-red light and by continious 758 nm irradiation. Far-red irradiation reverses almost completely the promoting effect of red light. The promoting effect (in the aurea mutant) and the inhibitory effect (in the wild-type) of continuous far-red light do not show photon fluence rate dependency above 20 nmol m⁻² s⁻¹. It is concluded that phytochrome controls tomato seed germination throgh low energy responses in both the wild type and the au mutant. The promoting effect of continuous and cyclic far-red light in the au mutant can be attributed to a greater sensitivity to P_fr.     

Cause of Senescence of Nine Sorts of Flowers

The levels of endogenous phytohormones and respiratory rate in nine sorts of flowers such as Cymbidium faberi Rolfe, Nopalxochia ackermannii Kunth and others were investigated both at full bloom and senescence and meanwhile the effect of exogenous phytohormones on prolonging the blossoms and promoting ethylene production were tested. There is a high content of endogenous ethylene in all the long-lived flowere, about 3–16 folds higer than the short-lived ones. There is a high level of ABA at full blooming flowers of short-lived flowers, in which there is no or only some cytokinins in it, but the ratio of CTK (6BA+zeatin)/ABA is smaller(l.7). The endogenous ABA reached a much higher level at senescence in all nine sorts of flowers, so it is reasonable to consider that it is ABA which plays an important role of regulation in controlling flower's senescence. There is a much higher level of GA3 and zeatin in the long-lived flowers which is not demonstrated in the shortlived ones. The respiratory rate is one of the factors controtling the longevity of flowers, but it does not play a decided role. Application of 6BA and zeatin prolongs distinctly orchid’s longevity, however exogenous IAA through the promotive action on ethylene production, evidently extends the longevity of the flowers of the Nopalxochia ackermannii Kunth.     

龙胆科药用植物化学成分的研究现状

龙胆科植物在我国的分布范围很广,且多数为药用植物,其多数种属的药用植物,至今其化学成分尚未被系统研究。综述了目前龙胆科药用植物的化学成分的研究现状及一般提取方法,对近年来发现的环烯醚萜及裂环烯醚萜类化合物进行了总结,为本科药用植物的更深入研究提供了参考。     

Interconnection of parameters of regulation system of lipid peroxidation and of morphophysiological parameters of mouse liver

A complex analysis of seasonal fluctuations of the mean group parameters of the system of regulation of lipid peroxidation has been performed in liver of Balb/c mice. Association of lipid characteristics and morphophysiological parameters is studied in the Balb/c mouse liver. An inter-connection is revealed between the liver index and the amount of lysoforms of phospholipids, the scale and character of the interconnection differing essentially depending on proportion of phos-phatidylcholine in mouse liver phospholipids.     

The effects of glutamine of the maintenance of embryogenic cultures of Cryptomeria japonica

Summary Embryogenic tissues of sugi (Cryptomeria japonica) were induced on a modified Campbell and Durzan (CD) medium containing 1 μM 2,4-dichlorophenoxyacetic acid (2,4-D) and 600 mg l⁻¹ glutamine, and subcultured in the medium of the same composition for over 1 yr. This resulted in a mixed culture of embryogenic and non-embryogenic cells. When embryogenic cells were isolated and cultured independently, their capacity to form embryogenic aggregates was lost. Thus, the non-embryogenic cells present within a mixed culture system were essential to the formation of embryogenic aggregates. When embryogenic tissues were isolated and cultured independently on a high glutamine-containing (2400 mg l⁻¹) medium, dry weights and endogenous levels of glutamine increased, and the tissue could generate a large number of embryogenic aggregates. Amino acid analysis of embryogenic and non-embryogenic cells from the maintenance culture indicated a higher level of glutamine was present in the latter. The high endogenous level of glutamine in the non-embryogenic portion of mixed cell masses may be the supplier of glutamine for maintaining the embryogenic property of the tissues.     

Specificity of action of piperidylcholine derivatives as substrates of cholinesterases of various origin

The review deals with study of enzymologic properties of a novel highly specific acetylcholinesterase substrate, N-(β-acetoxyethyl) piperidinium iodomethylate (“piperidylcholine”), and its 30 derivatives that were tested as effectors of cholinesterases of mammals and various species of Pacific squids. It was proven for the first time that responsible for specificity of action was structure of cyclic ammonium grouping of the alcohol part of molecule of the ester substrate. Analysis of specificity is performed based on enzymatic hydrolysis parameters—activity of catalytic center of cholinesterases and bimolecular constant of the reaction rate that are determined at optimal and low substrate concentrations. Among the specially synthesized group of thioester compounds there is revealed one more highly specific acetylcholinesterase substrate—N-(β-acetoxyethyl) piperidinium.     

Physiological characteristics of various species of strains of carboxydobacteria

Seven strains of aerobic carbon monoxide-oxidizing bacteria (carboxydebacteria) when growing on CO as sole source of carbon and energy had doubling times which ranged from 12–42 h. The activity profiles obtained after discontinuous sucrose density gradient centrifugation indicated that the CO-oxidizing enzymes are soluble and the hydrogenases are membrane-bound in all strains examined. The CO-oxidizing enzymes of Pseudomonas carboxydohydrogena, Pseudomonas carboxydoflava, Comamonas compransoris, and the so far unidentified strains OM2, OM3, and OM4 had a molecular weight of 230,000; that of Achromobacter carboxydus amounted to 170,000. The molecular weights of the CO-oxidizing and H₂-oxidizing enzymes turned out to be identical. The cell sonicates were shown to catalyze the oxidation of both CO and H₂ with methylene blue, thionine, phenazine methosulfate, toluylene blue, dichlorophenolindophenol, cytochrome c or ferricyanide as electron acceptors. Methyl viologen, benzyl viologen, FAD⁺, FMN⁺, and NAD(P)⁺ were not reduced. The spectrum of electron acceptors was identical for all strains tested. Neither free formate, hydrogen nor oxygen gas were involved in the CO-oxidation reaction. Methylene blue was reduced by CO at a 1:1 molar ratio. The results indicate that CO-oxidation by carboxydobacteria is catalyzed by identical or similar enzymes and that the reaction obeys the equation CO+H₂OCO₂+2H⁺+2e^- as previously shown for Pseudomonas carboxydovorans.Dedicated to Otto Kandler remembering almost three decades of enjoyable cooperation     

Modulation of allostery of pyruvate kinase by shifting of an ensemble of microstates

Since the introduction of the concepts of allostery about four decades ago, much advancement has been made in elucidating the structure-function correlation in allostery. However, there are still a number of issues that remain unresolved. In this review we used mammalian pyruvate kinase (PK) as a model system to understand the role of protein dynamics in modulating cooperativity. PK has a triosephosphate isomerase (TIM)(α/β)₈ barrel structural motif. PK is an ideal system to address basic questions regarding regulatory mechanisms about this common (α/β)₈ structural motif. The simplest model accounting for all of the solution thermodynamic and kinetic data on ligand-enzyme interactions involves two conformational states, inactive E^T and active E^R. These conformational states are represented by domain movements. Further studies provide the first evidence for a differential effect of ligand binding on the dynamics of the structural elements, not major secondary structural changes. These data are consistent with our model that allosteric regulation of PK is the consequence of perturbation of the distribution of an ensemble of states in which the inactive E^T and active E^R represent the two extreme end states. Sequence differences and ligands can modulate the distribution of states leading to alterations of functions. The future work includes: defining the network of functionally connected residues; elucidating the chemical principles governing the sequence differences which affect functions; and probing the nature of mutations on the stability of the secondary structural elements, which in turn modulate allostery.