水体浊度对菹草(Potamogeton cripus)幼苗生长发育的影响

用粒径小于100 μm的泥沙配置浊度为30、60、90、120、150 NTU和180 NTU的混浊水体,将菹草（Potamogeton cripus）幼苗分别移栽于上述水体中,观测菹草幼苗在各浊度水体中的生长发育状况,并用水下饱和脉冲叶绿素荧光仪（DIVING-PAM）测定菹草幼苗光合作用PSII最大量子产量 （Fv/Fm）、有效荧光产量（Yield）、光化学荧光淬灭系数（qP）、非光化学荧光淬灭系数（qN）等指标。结果表明,菹草幼苗对混浊水体有较强的耐受能力,在30、60NTU和90NTU的混浊水体中,水体浊度对菹草幼苗的存活、生长发育及光合结构PSII影响不显著（p>0.05）。当水体浊度≥120NTU时,在短期（<10d）胁迫下,水体浊度对于菹草幼苗的存活、生长发育无显著影响（p>0.05）,但是,随着胁迫时间的延长(>10d),菹草幼苗虽能成活但生长发育明显受到抑制,幼苗叶片受光胁迫时,能通过增加热耗散（qN）保护其光合结构PSII免受伤害;而更长时间的胁迫（80d）,在高浊度（120、150 NTU和180 NTU）水体中的菹草幼苗开始大量死亡,其Fv/Fm、Yield、qP值均显著低于对照（p<0.05）, qN值的急剧下降,说明光合结构PSII开始受到破坏。     

悬浮泥沙对亚洲苦草幼苗生长发育的影响

将亚洲苦草（Vallisneria asiatica Miki L.）幼苗植株种植于浊度分别为30NTU、60NTU和90NTU的悬浮泥沙水体中,统计各处理苦草幼苗的生长发育状况,并使用水下饱和脉冲叶绿素荧光仪（DIVING-PAM）测定PSⅡ最大量子产量（FV/Fm）、实际光化学效率（Yield）、光化学荧光淬灭系数（qP）、非光化学荧光淬灭系数（qN）、表观电子传递效率（ETR）以及快速光响应曲线。结果表明,实验第5天,悬浮泥沙对于苦草幼苗的存活、生长发育及光合作用影响不显著（p〉0.05）,苦草幼苗在低光胁迫下通过增加热耗散以保护PSⅡ。30d后,悬浮泥沙对于苦草幼苗的存活、生长发育及光合作用影响显著（p〈0.05）,30NTU组苦草幼苗生长发育虽明显受到抑制,但仍能保持一定的存活率;而泥沙浊度为60NTU和90NTU时则完全不利于苦草幼苗存活。30NTU、60NTU、90NTU组的Fv/Fm值、Yield值、qP值、最大ETR均显著低于对照（p〈0.05）,30NTU组最小饱和光强为176μmol quanta/m^2.s,而60NTU、90NTU组则只有17μmolquanta/m^2.s,远低于对照组的248μmol quanta/m^2.s。     

外源亚精胺对盐胁迫下黄瓜幼苗光合作用的影响

采用营养液栽培,研究了外源亚精胺对50mmol·L-1NaCl胁迫下黄瓜幼苗植株生长、叶片叶绿素含量、光合气体交换参数和叶绿素荧光参数(PSⅡ光化学效率)的影响。结果表明:NaCl胁迫显著降低了黄瓜植株生长量、净光合速率(Pn)、气孔导度(Gs)、胞间CO2浓度(Ci)(P<0.05),但对PSⅡ实际光化学效率(ФPSⅡ)、光化学淬灭(qP)、有效光化学效率(Fv′/Fm′)、非光化学淬灭(qN)和PSⅡ最大光化学效率(Fv/Fm)无显著影响(P>0.05);外源亚精胺显著提高了盐胁迫下黄瓜植株生长量、叶绿素含量、净光合速率、气孔导度、胞间CO2浓度,增加了ФPSⅡ、qP、Fv′/Fm′,降低了qN(P<0.05);外源亚精胺对Fv/Fm影响不显著(P>0.05)。外源施加亚精胺可增强盐胁迫下黄瓜植株的光合能力,主要是由于减弱了盐胁迫对植株的气孔限制,但对PSⅡ实际光化学效率影响较小,且叶面喷施比根施处理对改善盐胁迫下植株的生长和光合作用更有效。     

水体浊度对菹草萌发及萌发苗光合荧光特性的影响

用粒径小于100μm的泥沙分别配置浊度为30、60NTU和90NTU的混浊水体,将菹草（Potamogeton cripus）石芽分别种植于上述水体中,测定萌发率和萌发苗的株高、叶片数,并利用水下饱和脉冲荧光仪（DIVING-PAM）测定萌发苗的光合荧光特性。结果表明,水体浊度对石芽萌发率没有显著影响,但对萌发速率有一定影响;随着浊度的升高萌发苗株高和叶片数均显著降低（p＜0．05）;菹草萌发苗的有效荧光产量Yield也随水体浊度升高而降低,表明在高浊度水体中萌发苗天线色素吸收光子供给PSⅡ反应中心的效率下降;高浊度导致萌发苗吸收光能用于光化学电子传递的份额（qP）减少,第23天时90NTU水体中的妒为对照的91．4％;水体浊度上升导致qN显著升高,表明在高浊度、低光照胁迫下,萌发苗接收的光能更多的以热的形式耗散掉了,以避免光系统PSⅡ受到过剩光能的伤害;浊度升高引起电子在光合链中的传递速率（ETR）显著下降,第23天时在30、60NTU和90NTU水体中ETR分别为对照的93．3％、88．5％、75．8％,导致参与CO2固定的电子减少,光合作用降低。快速光响应曲线测定结果表明．萌发苗ETRmax和最小饱和光照强度随水体浊度的增加呈下降趋势,光响应能力随水体浊度的增加而显著下降,特别是在90NTU水体中萌发苗的光合作用能力下降显著。因此,在浅而混浊的水体中（水深70cm,浊度低于90NTU）,菹草石芽均能萌发,但是,水体浊度对萌发苗光合作用、生长速率有一定抑制作用。     

珙桐苗木叶片光合特性对土壤干旱胁迫的响应

通过控制土壤含水量,研究了土壤干旱胁迫对2年生珙桐(Davidia involucrata Baill.)幼苗叶面积、叶绿素含量、光合作用及叶绿素荧光参数的影响,以探讨珙桐光合作用对土壤干旱胁迫的响应机理.结果表明,干旱胁迫后,珙桐叶片失水脱落,各干旱胁迫处理叶面积比对照显著降低23%～98%,但单位面积的叶绿素含量却无显著变化;干旱处理的珙桐幼苗净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr)、水分利用效率(WUE)显著低于对照(P<0.05);干旱胁迫对珙桐幼苗叶片的初始荧光产量(F0)及最大荧光产量(Fm)没有产生显著影响,却显著降低了PSⅡ最大光化学量子产量(Fv/Fm)、PSⅡ实际光化学量子产量(Yield)、电子传递速率(ETR)及光化学淬灭系数(qP),使非光化学淬灭系数(qN)显著升高(P<0.05).研究发现,土壤水分亏缺对珙桐叶片的光合系统造成了不可逆的伤害,严重抑制了其正常的光合作用和生长发育;珙桐幼苗对土壤干旱胁迫极为敏感.     

紫花苜蓿(Medicago sativa)对干旱胁迫的光合生理响应

紫花苜蓿是重要的豆科牧草,具有较强的抗旱性,然而干旱仍是制约紫花苜蓿生产的主要逆境因子。通过盆栽试验,以抗旱性强弱不同的两种紫花苜蓿为试验材料,对干旱胁迫下紫花苜蓿的光合生理进行较为系统的研究,结果表明：（1）干旱胁迫下两种紫花苜蓿叶片净光合速率（Pn）、蒸腾速率(E)、气孔导度(Gs)、叶绿素含量(Chl)都有不同幅度的下降;叶绿体超微结构遭到破坏。相对于抗旱性弱的苜蓿,抗旱性强的苜蓿随干旱胁迫程度的加深,净光合速率下降较慢,叶绿体的外形及基粒结构受到的影响较小。（2）轻度干旱胁迫下气孔限制是两种紫花苜蓿Pn降低的主要因素,中度和重度干旱胁迫下非气孔限制是Pn降低的主要因素。（3）对叶绿素荧光参数的研究表明：干旱胁迫下两种紫花苜蓿PSⅡ反应中心光化学效率(Fv/Fm)、PSⅡ潜在活性(Fv/Fo)降低。总体上抗旱性强的紫花苜蓿Fv/Fm和Fv/Fo下降幅度小,PSⅡ利用光能的能力及PSⅡ的潜在活性均较强。PSⅡ光化学淬灭系数（qP）、非光化学淬灭系数（qN）的变化表现为干旱胁迫下两种紫花苜蓿qP值降低、qN值升高,总体上抗旱性强的紫花苜蓿qP降低的幅度低且qN升高幅度大,表明抗旱性强的紫花苜蓿PSⅡ反应中心电子传递活性受到的影响小,光合机构的损伤程度低。     

悬浮泥沙溶液对金鱼藻快速光响应曲线的影响

用粒径小于100μm的泥沙分别配置浊度为30、60、90 NTU的混浊溶液,将金鱼藻(Ceratophyllum dem er-sum)种植于该溶液中,1个月后测定植株叶片的快速光响应曲线,研究悬浮泥沙对金鱼藻光合荧光特性的影响。结果表明,在60、90 NTU的悬浮泥沙溶液中金鱼藻叶片的荧光产量(Ft)、光适应最大荧光产量(Fm′)和有效荧光产量(ΔFv/Fm)都显著低于对照和30 NTU的植株。与对照相比较,在混浊溶液中植株叶片的光化学淬灭(qP)和非光化学淬灭(qN)随光照强度的增加显著降低,光合能力和热耗散能力显著降低。混浊溶液中,随溶液浊度的增加植株最小饱和光强(Ek)和最大相对电子传递效率(rETRm ax)也显著低于对照植株,光合作用受到显著影响。因而,金鱼藻不适于在高浊度的悬浮泥沙溶液中生长。     

紫花苜蓿(Medicago sativa)对干旱胁迫的光合生理响应

紫花苜蓿是重要的豆科牧草,具有较强的抗旱性,然而干旱仍是制约紫花苜蓿生产的主要逆境因子。通过盆栽试验,以抗旱性强弱不同的两种紫花苜蓿为试验材料,对干旱胁迫下紫花苜蓿的光合生理进行较为系统的研究,结果表明：（1）干旱胁迫下两种紫花苜蓿叶片净光合速率（Pn）、蒸腾速率（E）、气孔导度（Gs）、叶绿素含量（Chl）都有不同幅度的下降;叶绿体超微结构遭到破坏。相对于抗旱性弱的苜蓿,抗旱性强的苜蓿随干旱胁迫程度的加深,净光合速率下降较慢,叶绿体的外形及基粒结构受到的影响较小。（2）轻度干旱胁迫下气孔限制是两种紫花苜蓿P。降低的主要因素,中度和重度干旱胁迫下非气孔限制是Pn降低的主要因素。（3）对叶绿素荧光参数的研究表明：干旱胁迫下两种紫花苜蓿PSⅡ反应中心光化学效率（F／F=）、PSⅡ潜在活性（Fv／Fo）降低。总体上抗旱性强的紫花苜蓿Fv／Fm和Fv／Fo下降幅度小,PSⅡ利用光能的能力及PSⅡ的潜在活性均较强。PsⅡ光化学淬灭系数（qP）、非光化学淬灭系数（qN）的变化表现为干旱胁迫下两种紫花苜蓿qP值降低、qN值升高,总体上抗旱性强的紫花苜蓿qP降低的幅度低且qN升高幅度大,表明抗旱性强的紫花苜蓿PSⅡ反应中心电子传递活性受到的影响小,光合机构的损伤程度低。     

高温胁迫下苋菜的叶绿素荧光特性

为了探明高温胁迫对苋菜(Amaranthus tricolor L.)光合过程的影响,用不同温度(25、30、35、40、45℃)处理苋菜植株1h后,随即测定了其叶绿素荧光动力学参数和快速光响应曲线特征参数的变化.结果表明:40℃以上高温胁迫下,苋菜叶片的光系统Ⅱ(PSⅡ)潜在光化学效率(Fv/Fo)、最大光化学效率(Fv/Fm)下降;最大荧光(Fm)、光合电子传递速率(ETR)、PSⅡ实际光化学效率(Yield)、光化学淬灭系数(qP)也均有所下降;而初始荧光(F.)和非光化学淬灭系数(NPQ)在40℃以上高温胁迫下显著上升.叶绿素荧光快速光响应曲线测定结果表明,初始斜率α、最大相对电子传递速率ETRmax和半饱和光强Ik在40℃以上高温胁迫下有所下降.研究表明,40℃以上高温胁迫对苋菜的光能的吸收、转换、光合电子传递和强光耐受能力等均有一定的影响.     

水分胁迫对不同抗旱类型冬小麦幼苗叶绿素荧光参数的影响

在人工气候室水培条件下,选用3个不同抗旱类型的冬小麦品种,研究了水分胁迫对冬小麦幼苗叶绿素荧光参数的影响。结果表明：水分胁迫下,冬小麦幼苗可变荧光(Fv)、最大荧光(Fm)、可变荧光与最大荧光比(Fv／Fm)、可变荧光与初始荧光比(Fv／Fo)、光化学淬灭系数(qF)均降低;而初始荧光(Fo)与非光化学淬灭系数(qNP)则升高,说明光系统Ⅱ(PSⅡ)受到了伤害,使得PSⅡ原初光能转换效率(Fv／Fm)、PSⅡ潜在活性(Fv／Fo)降低;光合电子传递、光合原初反应过程受到抑制,起光保护作用的热耗散提高。但水分胁迫下品种间各参数变化幅度不同。除qNF外,其余各参数均为抗旱性越强降低幅度越小,而qNF则升高幅度越大。说明水分胁迫对冬小麦幼苗叶绿素荧光参数的影响与其抗旱性密切相关。     

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.     

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.     

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。     

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.     

（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。