‘台农1号’芒果果实发育过程中的糖分积累与相关酶活性研究

以‘台农1号’芒果为材料,测定了果实生长发育过程中淀粉、蔗糖、葡萄糖和果糖含量以及淀粉酶、蔗糖代谢相关酶———酸性转化酶(AI)、中性转化酶(NI)、蔗糖合成酶(SS)和蔗糖磷酸合成酶(SPS)的活性,并对果实中糖组分与酶活性的关系进行了分析.结果显示,(1)台农1号芒果果实属于单S型生长曲线,发育前期主要积累淀粉、葡萄糖和果糖,果实成熟软化时,淀粉酶活性降至最低,淀粉水解,蔗糖快速积累.(2)酸性转化酶活性在果实整个发育过程中维持最高,完熟时略有降低;蔗糖磷酸合成酶在果实发育前期略有降低,完熟时升至最高;蔗糖合成酶和中性转化酶活性在整个发育期一直很低且较稳定.(3)淀粉含量与淀粉酶活性呈显著正相关,与SPS活性呈极显著负相关,蔗糖、葡萄糖含量均与SPS、SS呈显著、极显著的正相关;果糖含量与SS呈极显著的正相关.研究表明,芒果成熟时淀粉分解、酸性转化酶活性的降低,且蔗糖合成酶和蔗糖磷酸合成酶活性的增加是引起果实蔗糖积累的主要因子.     

外源水杨酸对氯化钠胁迫下番茄幼苗糖代谢的影响

采用营养液水培法,用100、300和500 mg·L^-1不同浓度的水杨酸（SA）处理‘辽园多丽’番茄幼苗,测定在NaCl胁迫下番茄幼苗叶片果糖、葡萄糖、蔗糖含量和蔗谢代谢相关酶活性（酸性转化酶AI、中性转化酶NI、蔗糖磷酸合成酶SPS、蔗糖合成酶活性SS）的变化.结果表明：SA处理叶片可以维持或提高NaCl胁迫条件下番茄幼苗叶片果糖、葡萄糖含量及AI、NI、SPS和SS活性,其最高值分别比单纯NaCl处理植株增加30.0%、31.1%、24.7%、27.9%、22.0%和24.5%;但对NaCl胁迫条件下番茄幼苗叶片蔗糖含量的影响不大.表明水杨酸可以通过提高NaCl胁迫下番茄叶片转化酶活性来提高番茄叶片果糖和葡萄糖含量,从而缓解NaCl胁迫对番茄的伤害,其中以500 mg·L^-1的SA处理效果较理想.     

睡莲叶脐着生胎芽与叶片不同部位碳水化合物代谢的关系

为了解睡莲叶脐胎芽的发育机理,以广热带亚属胎生睡莲‘玛格丽特’和‘鲁比’为材料,非胎生睡莲‘粉星’为对照,采用石蜡切片技术观察叶脐胎芽发育4个时期的形态变化,并比较胎生与非胎生睡莲叶片不同部位碳水化合物代谢的差异性。结果表明: 叶片展开后,胎生睡莲叶脐表皮以下细胞不断分裂和生长,形成排列紧密的细胞群,并逐渐向上凸起呈球形,非胎生睡莲叶脐则无任何变化。随着叶片的不断发育,除蔗糖和酶活性以外,各生理指标在胎生睡莲叶片中的含量均表现为先升后降,显著高于非胎生睡莲;从不同部位来看,碳水化合物含量总体表现为叶片>叶脐>叶柄(淀粉含量除外,其叶脐高于叶片和叶柄);不同品种蔗糖代谢酶活性表现为蔗糖合成酶(SS)和酸性转化酶(AI)活性高于蔗糖磷酸合成酶(SPS)和中性转化酶(NI)活性,胎生睡莲不同组织中的SPS和NI活性均显著高于非胎生睡莲,但SS和AI活性在胎生睡莲中并未表现出明显的品种优势;AI活性在品种间差异大,NI活性在品种间差异较小,且在不同组织中均处于较低水平。相关性分析表明,‘鲁比’叶片的蔗糖含量与SPS和AI呈极显著正相关,与NI呈显著正相关,且蔗糖含量的积累主要增加了睡莲叶片的SS和NI活性,有利于促进胎芽的形成。     

甘草叶片渗透调节物质及蔗糖代谢相关酶对干旱胁迫的响应特性

该研究以甘草幼苗为试材,采用盆栽自然干旱方法,设计对照(CK)、轻度(LS)、中度(MS)、重度(SS)干旱胁迫处理,测定分析甘草叶片的渗透调节物质及蔗糖代谢相关酶[蔗糖磷酸合成酶(SPS)、蔗糖合成酶合成方向(Ss+)、蔗糖合成酶分解方向(Ss-)、中性转化酶(NI)、酸性转化酶(AI)、淀粉磷酸化酶(SP)]活性的变化,以探讨甘草的渗透调节特性以及糖分调节的酶学机制,揭示甘草对干旱胁迫的响应机理。结果显示:(1)随着干旱胁迫程度的加剧,甘草叶片可溶性糖、可溶性蛋白和脯氨酸含量呈逐渐增加的趋势,束缚水/自由水的比值呈先增加后降低的趋势。(2)随着干旱胁迫程度的加剧,甘草叶片蔗糖、葡萄糖、果糖含量均呈先升高后降低的趋势,但不同胁迫强度出现峰值的时间不同;其中在CK和LS干旱胁迫时蔗糖含量淀粉含量葡萄糖含量果糖含量,在MS和SS干旱胁迫时淀粉含量葡萄糖含量蔗糖含量果糖含量,表明随着干旱程度的增加,甘草叶片中蔗糖转化成了淀粉。(3)随着干旱胁迫程度的加重,甘草叶片的SPS活性呈先升高后降低的趋势,Ss活性和Inv(蔗糖转化酶)活性呈逐渐升高的趋势,SP活性呈逐渐降低的趋势;各胁迫处理的Ss+活性与CK差异不显著,而Ss-活性与CK差异显著,并且Ss-活性在各胁迫处理下远大于Ss+活性,表明甘草叶片Ss-活性在蔗糖代谢过程中占主导作用。(4)相关分析结果显示,在LS中,NI与蔗糖呈负相关关系,Ss-与淀粉呈显著正相关关系、与蔗糖呈负相关关系;在MS中,蔗糖和葡萄糖与SPS、Ss+、Ss-、NI和AI均呈正相关关系,与SP呈负相关关系;在SS中,SP和NI与蔗糖呈正相关关系,而与淀粉呈负相关关系;表明在轻度干旱处理下,Ss参加了蔗糖的分解,继而合成淀粉;在中度和重度干旱条件下,SP主要催化淀粉的分解来增加蔗糖含量以此平衡蔗糖代谢。     

套袋对梨果实发育过程中糖组分及其相关酶活性的影响

以翠冠和黄金梨为试材,测定套袋和未套袋(对照)梨果实发育时期果实中蔗糖、葡萄糖、果糖和山梨醇含量以及蔗糖代谢相关酶酸性转化酶(AI)、中性转化酶(NI)、蔗糖合成酶(SS)和蔗糖磷酸合成酶(SPS)的活性,并对果实中糖组分积累与酶活性的关系进行了分析.结果表明:(1)两梨品种套袋果实在发育过程中蔗糖、葡萄糖、果糖、山梨醇和糖代谢相关酶活性变化趋势与对照基本一致,套袋果实糖含量均低于对照但差异不显著,而各相关酶活性在两类果实间差异表现各异.(2)在梨果实发育早期,果实中以分解酶类为主,糖分积累低;发育后期以合成酶类为主,糖分积累多.(3)两品种套袋和对照果实AI活性与葡萄糖含量均呈显著或极显著正相关,SS合成方向活性与蔗糖含量均为极显著正相关,且翠冠对照果SPS活性与蔗糖含量呈极显著正相关.可见,套袋通过提高果实发育早期转化酶(Inv)活性,降低果实后期蔗糖磷酸合成酶(SPS)、蔗糖合成酶(SS)的活性来影响糖分积累,从而影响梨果品质.     

宁夏枸杞果实糖积累和蔗糖代谢相关酶活性的关系

通过对枸杞果实发育过程中果实生长模式、蔗糖、果糖、葡萄糖和淀粉含量及糖代谢相关酶活性的测定,研究了宁夏枸杞果实生长发育过程中糖的代谢积累与相关酶活性的关系.结果表明:(1)宁夏枸杞果实发育呈双S"曲线,果实主要以积累己糖为主.(2)蔗糖磷酸合成酶(SPS)活性在果实发育初期处于下降的趋势,在花后19d开始上升,果实转色后又逐渐下降;蔗糖合成酶(SS)活性总体表现为SS分解方向的活性大于SS合成方向的活性,说明枸杞果实发育过程中,SS的活性主要以分解方向的为主;酸性转化酶(AI)和中性转化酶(NI)的活性随果实发育呈上升趋势,但在果实成熟后期有所下降,且AI和NI活性高于合成酶类的活性,较高的转化酶类活性促进了果实内部己糖的积累.(3)在枸杞果实生长发育中,葡萄糖和果糖含量与AI和NI均呈极显著正相关,而与其它酶不具有相关性.说明AI和NI在宁夏枸杞果实的糖代谢中起着主要的调控作用.     

干旱胁迫下紫花苜蓿幼苗非结构性碳水化合物代谢对NO的响应

以紫花苜蓿（Medicago sativa）为材料,采用盆栽试验方法,用聚乙二醇（PEG-6000）作为渗透介质模拟干旱胁迫,外源喷施NO供体硝普钠,NO清除剂（carboxy-PTIO,cPTIO）,对紫花苜蓿幼苗叶片、根系中非结构性碳水化合物含量及相关酶活性的变化进行研究,探讨NO对紫花苜蓿耐旱机制的作用。结果表明：外源NO促进了紫花苜蓿叶片中淀粉的分解、根系中淀粉的积累,提高叶片及根系中可溶性糖（蔗糖、果糖和葡萄糖）含量,降低了渗透势,促进细胞吸水,缓解干旱造成的损伤。此外,外源NO能提高干旱胁迫下紫花苜蓿叶片中蔗糖合成酶（SS）、酸性转化酶（AI）和中性转化酶（NI）活性,降低了蔗糖磷酸合成酶（SPS）的活性,提高根系中SS、SPS和转化酶活性,使蔗糖的合成与分解处于高水平的动态平衡,增强了紫花苜蓿的抗旱性。而NO清除剂cPTIO则会不同程度的抑制紫花苜蓿幼苗中非结构性碳水化合物（NSC）及其相关酶活性。因此,NO可以通过调控NSC的代谢响应干旱胁迫,缓解干旱胁迫造成的不利影响,在紫花苜蓿的抗旱中扮演着重要的角色。     

干旱胁迫对宁夏枸杞叶片蔗糖代谢及光合特性的影响

以宁夏枸杞品种‘宁杞1号’为材料,采用防雨棚内盆栽控水法研究了轻度干旱(LD)、中度干旱(MD)、重度干旱(SD)和正常灌水(CK)4种土壤水分条件下枸杞叶片糖分含量、蔗糖代谢酶活性和光合参数的响应规律,为宁夏枸杞在干旱地区高产栽培提供参考依据。结果显示:(1)干旱胁迫降低了枸杞青果期叶片蔗糖和淀粉含量,轻度干旱胁迫可提高枸杞色变期叶片果糖和蔗糖含量,而成熟期叶片淀粉含量则随着干旱加重而升高。(2)干旱胁迫降低了青果期枸杞叶片中性转化酶(NI)、蔗糖磷酸合成酶(SPS)和蔗糖合成酶(SS)的活性,降低了色变期和成熟期叶片酸性转化酶(AI)和SS的活性,但提高了色变期和成熟期叶片NI的活性。(3)随着干旱胁迫的加剧,叶片净光合速率(Pn)、蒸腾速率(Tr)和气孔导度(Gs)呈降低趋势,瞬时水分利用率(WUE)呈现:LD>CK>SD>MD的变化趋势。研究认为,轻度干旱胁迫能促进宁夏枸杞成熟期叶片蔗糖积累和水分利用率提高,有利于更多光合同化物输送到果实中。     

苹果果实糖积累特性与品质形成的关系

以'富士'和'国光'苹果为研究对象,对其果实发育过程中糖含量及其代谢关键酶活性的变化进行测定分析,以揭示糖分积累代谢特性对果实品质形成的影响.结果表明:(1)'富士'和'国光'均为己糖积累型果实, '富士'果实以积累果糖最多,果糖/葡萄糖(F/G)值为1.56,而'国光'以积累葡萄糖最多,F/G值仅为0.68;蔗糖在两品种中含量和所占比例均很低,在近成熟期'富士'高于'国光'.(2)'富士'果实蔗糖磷酸合成酶(SPS)和蔗糖合成酶(SS)活性均随果实糖的累积量增加而显著升高,酸性转化酶(AI)活性也渐趋升高,而中性转化酶(NI)活性波动不大,且其糖累积与AI和SPS活性相关性最大,而与NI相关性不大,SS的作用主要表现在发育后期;在 '国光'果实糖积累过程中SPS起主导作用,SS和NI的作用主要表现在发育前期,而AI的作用不大.(3)'富士'和'国光'果实淀粉含量变化趋势相同,在淀粉积累高峰之后,'富士'果实淀粉降解速度更快,其淀粉含量迅速下降且低于'国光',此时其相应淀粉酶活性也高于'国光'.研究发现,'富士'和'国光'果实糖积累和淀粉代谢均存在显著差异,从而直接或间接地影响着果实糖代谢过程,进而导致果实品质的显著差异.     

乙酰水杨酸在番茄果实发育期间对蔗糖代谢相关酶活性的影响

研究不同浓度乙酰水杨酸(ASA)对番茄品种‘辽园多丽’果实发育期间蔗糖代谢相关酶影响的结果表明:ASA可抑制果实的维管束和胶质胎座中酸性转化酶(AI)和中性转化酶(NI)活性,而提高蔗糖合成酶(SS)与蔗糖磷酸合成酶(SPS)活性;心室隔壁和中果肉中ASA的作用与此相反。ASA促进果实维管束中可溶性糖积累主要通过调控AI和NI活性实现,而在胶质胎座中主要通过调控SS活性实现;在中果肉和心室隔壁中主要通过调控SS和AI活性实现。     

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.