铬、硒对水稻幼苗生长和生理的影响

以单一铬(Cr6+0～200μmol·L1)及硒(Se0～200μmol·L1)、铬硒混合液(铬100μmol·L1,硒50μmol·L1)处理水稻幼苗,研究不同处理和浓度对水稻幼苗生长和生理特性影响。结果表明(1)单一铬处理,随着铬浓度增加,植株生长明显受到抑制,铬毒害表现为株高、鲜重和干重受抑制,叶片黄色、叶绿素含量下降,体内SOD、CAT活性下降,POD活性上升,膜透性增大;(2)单一硒处理,50μmol·L1促进植株生长,100μmol·L1和200μmol·L1则抑制植株生长;(3)铬硒混合处理结果反映,硒有减轻水稻铬毒害的作用,表现为:减轻铬胁迫对株高、鲜重和干重增加的抑制,提高叶绿素含量,提高SOD、CAT活性,降低POD活性和膜透性。     

汽车尾气污染对四种北方阔叶树苗木膜脂过氧化和保护酶活性的影响

采用相同浓度(25μgNO2·m^-3)不同处理时间(1、3、5、7d)和相同处理时间(2h)不同浓度(40、60、80、100μgNO2·m^-3)两种方法进行熏气处理,研究了汽车尾气对五角槭、山荆子、山梨和茶条槭苗木叶液pH值、相对电导率、MDA含量、叶绿素含量、SOD和POD活性及ASA含量的影响．结果表明．随着熏气时间的延长和熏气浓度的增加,4个树种苗木的叶液pH值、叶绿素含量和ASA含量均逐渐降低,相对电导率、MDA含量、SOD和POD活性逐渐上升,不同树种苗木叶片组织的各项指标间存在较大差异,相同浓度处理7d后．山梨苗木叶片组织的pH降幅最大,山荆子次之,茶条槭最小;叶绿素含量的下降顺序为山梨>山荆子>茶条槭>五角槭;ASA含量的下降幅度以五角槭和茶条槭较小,山荆子和山梨较大,随着处理时间的延长．五角槭苗木叶片组织的相对电导率和MDA含量上升幅度最大．分别比对照升高了68．1％和52．50％,山荆子次之,茶条槭最小．随着处理浓度的增加,山荆子苗木的相对电导率和MDA上升幅度最大,分别比对照升高99．8％和52．5％,山梨次之,五角槭和茶条槭较小．4个树种苗木的自由基清除系统受到明显影响．SOD、POD活性呈上升趋势,茶条槭除ASA变幅稍高于五角槭外．各项生理指标的变化明显低于其它3个树种,表现出相对较强的抗性,山荆子的各项生理指标变化幅度相对较大,且其SOD和POD在最高浓度处理时开始遭到破坏．表现出相对较弱的抗性。     

外源亚精胺对Ca(NO3)2胁迫下黄瓜幼苗生长和活性氧代谢的影响

以温室专用黄瓜品种'津优3号'幼苗为材料,采用营养液栽培方法,研究了叶面喷施1 mmol·L-1亚精胺(Spd)对60 mmol·L-1硝酸钙胁迫下黄瓜幼苗生长和植株体内活性氧代谢的影响.结果显示,Ca(NO3)2胁迫下,黄瓜幼苗叶片和根系O-·2产生速率显著增加,超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)等抗氧化酶活性升高,同时MDA含量和相对电导率明显提高,显著降低了黄瓜幼苗的株高、鲜重和干重;外源喷施Spd提高了硝酸钙胁迫下黄瓜幼苗叶片和根系SOD、POD和CAT活性,降低了O-·2产生速率,MDA含量及相对电导率显著下降.由此可见,外源Spd可通过提高黄瓜幼苗SOD、POD和CAT等保护酶活性来增强其对体内活性氧的有效清除能力,降低膜质过氧化伤害程度,从而缓解硝酸钙胁迫对黄瓜幼苗生长的抑制.     

CaCl2对铁棍山药块茎采后几种与膜脂过氧化相关的生理指标的影响

铁棍山药决茎采后经0．1％-1.0％（WIV）的CaCl2溶液处理后,其含水量增加,相对电导率减小,丙二醛（MDA）含量降低,超氧化物歧化酶（SOD）活性升高,超氧阴离子（O2^-）产生速率下降;而浓度为2．0％的CaCl2溶液则促进铁棍山药块茎贮藏后期SOD活性下降,对含水量增加和相对电导率、MDA含量以及O^2-产生速率下降的效果不稳定。     

山杜英和黧蒴幼苗对干旱胁迫(PEG)的生理响应

以山杜英(Elaeocarpus sylvestris)和黧蒴(Castanopsis fissa)幼苗为试验材料,利用聚乙二醇6000(PEG-6000)人工模拟水分胁迫环境,设置三个胁迫强度处理(轻度、中度、重度)、三个胁迫持续时间处理(12h、24h、36h),以不加PEG.6000的1/2Hoagland营养液中的苗木作为对照,对2个树种幼苗的叶片相对含水量、相对电导率、脯氨酸含量、叶绿素含量、超氧化物歧化酶(SOD)活性、丙二醛(MDA)含量和可溶性糖含量进行了测定,研究了水分胁迫对这2种幼苗的影响.结果表明:随着水分胁迫强度的加深及持续时间的延长,2种幼苗叶片相对含水量出现下降趋势,黧蒴的含水量下降更为显著;2种树种幼苗叶片内相对电导率呈波动性上升,黧蒴在轻度胁迫时相对电导率有大幅增加;2种幼苗的脯氨酸含量显著增加,叶绿素含量呈小幅波动,SOD活性先升后降,可溶性糖含量呈现波动性上升;山杜英叶片的MDA含量增加较缓慢,而黧蒴叶片的MDA含量大幅度增加.研究表明幼苗山杜英比黧蒴抗旱性强,叶片相对含水量、相对电导率和MDA含量可作为评价这2种苗木抗旱性的依据.     

美丽箬竹对模拟大气O3浓度倍增胁迫的生理响应

运用开顶式气室(OTCs)模拟当前环境大气O3浓度(对照,40～45 nL·L-1)、O3浓度倍增4倍(TR-1,92～106 nL·L-1)和O3浓度倍增2倍(TR-2,142～160 nL·L-1)胁迫,以叶片光合色素、MDA、可溶性蛋白质和可溶性糖含量及SOD和POD活性和相对电导率为指标,分析了美丽箬竹(Indocalamus decorus Q.H.Dai)对O3胁迫的生理响应规律.结果显示:随O3浓度的提高,叶片叶绿素a(Chla)、叶绿素b(Chlb)、总叶绿素和类胡萝卜素含量,SOD和POD活性,可溶性蛋白质和可溶性糖含量及二者的比值(SPC/SSC)均呈下降趋势;叶绿素a口与b的比值(Chla/Chlb)、MDA含量和相对电导率均呈增加趋势.TR-1条件下叶片POD活性和可溶性糖含量分别比对照下降38.86％和10.37％,差异显著;Chla/Chlb比值显著高于对照,其余指标均与对照无显著差异.而在TR-2条件下叶片Chla、Chlb、总叶绿素和类胡萝卜素含量显著低于对照,降幅分别为26.89％、40.91％、30.47％和20.37％;SOD和POD活性、可溶性蛋白质和可溶性糖含量以及PC/SSC比值也均显著低于对照,降幅分别为42.03％、46.62％、45.09％、11.52％和40.15％;Chla/Chlb比值、MDA含量和相对电导率均显著高于对照.另外,TR-1与TR-2处理组间光合色素含量和POD活性差异不显著,TR-2处理组MDA含量和相对电导率显著高于TR-1处理组,SOD活性显著低于后者.研究结果表明:美丽箬竹对O3胁迫具有强耐受性,可种植于O3浓度较高的环境中.     

铬对烟草组培苗生长和某些生理指标的影响

以烟草无菌苗为材料,在培养基中添加0、50、100、150、200、300μmol.L-1浓度的重金属铬离子,进行组织培养,35d后分析植株生长和相关生理变化。结果表明,低浓度(50μmol.L-1)铬对烟草组培苗生长有促进作用,株高、鲜重、叶绿素含量、蛋白质含量、SOD活性呈现上升趋势;高浓度铬处理则抑制生长,株高、鲜重、叶绿素、蛋白质含量、SOD活性都下降,相反,POD活性、MDA含量和细胞膜透性显著增加。     

水杨酸对苦瓜叶片白粉病抗性及抗氧化酶活性的影响

以‘碧绿3号’苦瓜幼苗为材料,采用100、500和1000μmol.L-1的水杨酸(SA)溶液预处理后进行白粉菌的诱导接种,研究了SA处理对苦瓜叶片光合色素含量和4个抗氧化酶活性的影响。结果显示:各浓度SA处理苦瓜植株的病情指数均显著低于对照(蒸馏水处理),并随SA处理浓度增加而逐渐下降;各SA处理苦瓜叶片的光合色素含量均高于其对照,且随SA处理浓度升高而逐渐增加;苦瓜叶片APX、CAT和GR活性随SA处理浓度增加而升高,但GPX活性反而下降,各处理CAT和GR活性增幅均高于病情指数增幅,1000μmol.L-1SA处理的APX活性增幅也高于病情指数增幅。研究发现,SA处理可以提高苦瓜感染白粉病植株叶片的光合色素含量及其抗氧化酶活性,显著降低其病情指数,增强其白粉病抗性,且以1000μmol.L-1SA处理效果最好。     

水杨酸对高温胁迫下皖贝母生理生化特性的影响及其时效性研究

以盆栽皖贝母幼苗为试验材料,分别于叶面喷施0.5mmol/L水杨酸(SA)溶液后1、3、5、7d进行高温(36℃)胁迫24h,再进行恢复生长(昼25℃/夜20℃)48h,研究外源SA缓解皖贝母高温胁迫伤害的可行性及其时效性。结果显示:叶面喷施SA后3d内可显著提高皖贝母幼苗叶绿素a及可溶性蛋白含量,显著降低其相对电导率及MDA含量;同时可增强皖贝母幼苗叶片SOD、POD活性,抑制CAT活性。但上述作用效果在叶面喷施SA后5d明显减弱,7d后则几乎完全丧失。研究表明,0.5mmol/L外源SA能通过提高渗透调节物质含量和保护酶活性来有效减轻高温对皖贝母叶片的伤害,且其有效作用时间为3d。     

外源IAA对NaHCO3胁迫下黄瓜幼苗光合特性和抗氧化系统的影响

以黄瓜‘津研四号’幼苗为试材,采用Hoagland营养液栽培,研究了不同浓度(0、0.01、0.1、1和10μmol·L-1)IAA处理对50 mmol·L-1 NaHCO3胁迫下黄瓜幼苗光合特性及抗氧化系统的影响。结果表明,碱胁迫对黄瓜幼苗的生长有抑制作用,0.01~1μmol·L-1外源IAA处理可显著增加黄瓜幼苗的生物量;使叶中Na+积累降低,K+积累增加,且IAA的缓解效果具有浓度效应。叶绿素a、叶绿素b和类胡萝卜素含量提高,净光合速率(Pn)和气孔导度(Gs)增加,以1μmol·L-1 IAA处理的效果最好。添加1μmol·L-1外源IAA显著提高了碱胁迫下黄瓜叶中超氧化物歧化酶(SOD)、过氧化物酶(POD)、抗坏血酸过氧化物酶(APX)、脱氢抗坏血酸还原酶(DHAR)和谷胱甘肽还原酶(GR)的活性及还原型抗坏血酸(AsA)和谷胱甘肽(GSH)的含量,降低了碱胁迫诱导的活性氧积累和膜脂过氧化反应;而10μmol·L-1外源IAA处理则加剧碱胁迫对黄瓜幼苗的危害。     

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.     

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.     

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.     

History of the discovery of the mode of transmission of yellow fever virus

This essay documents and examines the historical circumstances and events surrounding the discovery of the mode of transmission of yellow fever virus in Cuba. Close scrutiny of the articles published by Walter Reed and his colleagues in 1900, 1901 and 1902 reveals their limitations as historic documents. Fortunately, other sources of information from that period survive in letters and documents written by individuals involved in the quest for the mode of transmission. Examination and comparison of those sources of information unveiled a fascinating story which reveals that misunderstandings engendered by published articles accorded merit where it was not fully due.     

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.     

真菌类遗传学分析的知识结构教学

本文以认知结构理论为指导,讨论了真菌类遗传分析与高等动植物遗传分析的内在联系,认为利用这种内在联系进行教学可收到好的效果并说明了作者的具体教学过程。 Abstract:In the paper, the relationship between genetic analysis of Fungi and genetic analysis of high animal and plant was discussed.A good results were obtained when we adopted this method in the teaching.     

（鱼句）亚科花（鱼骨）型鱼类骨骼系统的比较

对我国花型Hemibarbuspattern鱼类作了骨骼系统比较,结果表明,此类型鱼类脑颅较长,副蝶骨平直或稍弯曲,眶蝶骨腹纵嵴发达(铜鱼Coreius septentrionalis例外),下颞窝和咽突中等大,基枕骨后突发达;脑颅中的上筛骨的后突、侧筛骨的外筛突,蝶耳骨的外突、上耳骨的后突、围眶骨和后颞窝等均有明显的差异;咽颅中的舌颌骨、尾舌骨、鳃盖骨和下咽齿的列数等又有显著的区别;附肢骨骼中的腰带骨、脊椎骨中的复合神经骨和第4椎骨腹侧的悬器等也有不同之处。据此,这些差异和区别可作为属间或种间的分类依据。