Te(Ⅳ)胁迫对两种螺旋藻生长及抗氧化酶系统的影响

在钝顶螺旋藻(Spirulina platensis)和极大螺旋藻(Spirulina maximum)接种的第5天至第10天添加不同浓度的亚碲酸钠,研究Te(Ⅳ)胁迫对两种螺旋藻的生长、抗氧化活性系统和脂质过氧化作用的影响。结果表明,通过调节添加碲的时间,可以有效地调节碲胁迫强度,随着加碲时间依次后移,碲胁迫强度逐渐减小,螺旋藻的最终生物量递增。碲对螺旋藻的生物效应与碲胁迫强度有关,也与添加碲时藻所处的生长期有关。实验组Ⅲ(分别在第7、8、第9天三天添加碲)的碲胁迫强度并不是最低的,两种螺旋藻的最终生物量也不是最大,但MDA的含量却是最低的,表明该实验组的生长状态是最佳的。各种抗氧化酶(SOD、GPX、CAT、APX和POD)的活性变化情况较复杂。其中,在碲胁迫下,GPX的活性显著提高。       

硒对H2O2胁迫钝顶螺旋藻的保护作用及其机制

以钝顶螺旋藻(Spirulina platensis)为实验对象,用H2O2构建氧化损伤模型,研究不同浓度硒对H2O2胁迫钝顶螺旋藻的生长、干重、水溶性蛋白、光合色素、抗氧化酶(SOD、POD、APX、CAT和GSH-PX)及丙二醛(MDA)含量的影响,探讨硒作为过氧化保护剂的可能性及其机制.结果显示:(1)在 0.25～2.5 mmol/L H2O2胁迫下,钝顶螺旋藻的藻密度、干重均显著降低,藻丝出现明显的断裂、破碎,藻体中MDA含量呈剂量性增加.(2)预添加一定浓度(2～1 000 μmol/L)的Na2SeO3可显著抑制1 mmol/L H2O2胁迫下的钝顶螺旋藻藻密度和干重的降低趋势,改善藻丝的断裂受损,诱导藻体中SOD、POD、APX、CAT和GSH-PX抗氧化酶系活性的提高,同时显著增加水溶性蛋白的含量,缓解脂溶性色素的降解,降低MDA的积累和羟自由基的相对含量,拮抗H2O2诱导的氧化损伤.研究表明,硒的预处理可以有效提高钝顶螺旋藻的抗氧化能力,对氧化胁迫引起的生理伤害起到明显的缓解作用,以达到较理想的保护效果.     

两种螺旋藻在不同生长阶段的硒胁迫和生物有机化效应

在极大螺旋藻(S.maxima)和钝顶螺旋藻(S.platensis)不同生长阶段进行硒胁迫处理,分别从接种后第1d至第5d开始添加硒,并不断增加硒含量,至第7d使硒的累计添加量为1000mg·L^-1,形成5种不同硒胁迫(硒胁迫Ⅰ～Ⅴ),观察各种硒胁迫下螺旋藻的生物量及对无机硒的生物有机化的影响。结果表明:硒胁迫Ⅰ～Ⅳ对两种螺旋藻的生长影响不明显,而硒胁迫Ⅴ对螺旋藻生长有明显促进作用;藻体含硒总量和螺旋藻对无机硒的有机化率按硒胁迫Ⅰ～Ⅴ依次增加。首次提出硒胁迫强度概念,并用此较好地解释了有关实验结果。     

富硒螺旋藻培养技术研究

采用富硒技术对印项螺旋藻培养进行强化,对硒（IV）浓度和亚硫酸盐的影响,以及硒的生物富集及其对藻细胞分子官能团结构的影响等进行了较为详细的研究,并对相关的可能机理进行了讨论。研究发现,硒对印顶螺旋藻生长具有刺激或抑制的双重作用。在0.02mg/L-411.00mg/L浓度范围内,硒不仅可以加快印顶螺旋藻的生长,而且还可以提高其生物量;同时,钝顶螺旋藻对硒的事集随着硒浓度的增加而增加,较为缓慢的生长利于钝顶螺旋藻对硒的富集。研究还证实,NaSO3会减轻高浓度Na2SeO3对印顶螺旋藻生长的毒性,富硒培养不会对藻细胞分子官能团结构产生损害。实验得出钝顶螺旋藻富硒培养较佳的硒处理浓度在10mg／L－40mg／L。     

钝顶螺旋藻富集转化硒及硒在藻体中的分布

钝顶螺旋藻在４℃、避光、隔离空气条件下,对硒的吸附量死体显著高于活体。藻体对硒的最大富集量为６２７．４μg.g^-1(DW),培养基中硒浓度在３００μg.ml^-1以下时有机硒转化率大于８０％。藻体中的硒主要分布在水溶性组化率大于８０％。藻体中的硒主要分布在水溶性组分中,占总硒的６５％以上,蛋白质硒占有机硒的７１．９％,多糖、核酸也有一定量硒分布。     

亚硒酸钠、酵母硒和富硒螺旋藻对杂交鲟幼鱼生长、抗氧化能力及组织硒含量的影响

实验旨在研究饲料中不同类型和水平的硒源对杂交鲟(Acipenser baerii♂×Acipenser schrenckii♀)幼鱼生长、抗氧化能力及组织硒含量的影响。不同类型的硒源为亚硒酸钠、酵母硒和富硒螺旋藻,添加水平为0、0.4和1.2 mg/kg,制作对照饲料(C)、亚硒酸钠添加饲料(S1和S2)、酵母硒添加饲料(Y1和Y2)和富硒螺旋藻添加饲料(P1和P2)。使用实验饲料饲喂初始体重为(7.82±0.12) g的杂交鲟幼鱼,养殖62d。结果表明,不同硒源和硒水平对杂交鲟幼鱼的特定生长率和饲料效率无显著影响(P>0.05)。高水平亚硒酸钠显著提高了全鱼和肝脏硒含量(P<0.05),但对肌肉和脊椎骨硒含量无显著影响(P>0.05)。高水平酵母硒和富硒藻螺旋添加组杂交鲟幼鱼的全鱼、肝脏、肌肉及脊椎骨硒含量均显著高于对照组(P<0.05)。酵母硒添加组的血浆总蛋白(TP)和总胆固醇(TC)含量均显著高于对照组(P<0.05)。同时,高水平硒添加组杂交鲟幼鱼的血浆谷胱甘肽过氧化物酶(GSH-Px)活性显著高于对照组和低水平硒添加组(P<0.05)。亚...     

大黄鱼幼鱼对饲料硒的需求量

为确定大黄鱼(Larimichthys croceus)对饲料硒的需求量, 以Na2SeO3为饲料硒源, 配制6种饲料, 硒的添加水平分别为0(对照组)、0.05、0.2、0.4、0.6和0.9 mg/kg, 实测值分别为0.08、0.16、0.27、0.44、0.66和0.96 mg/kg。在海水浮式网箱中养殖初始体重为(9.140.09) g的大黄鱼幼鱼10周, 结果表明增重率(WG)、全鱼和骨骼中的硒含量随着饲料硒含量的升高而显著升高(P0.05)。当饲料硒含量分别超过0.27、0.66、0.66 mg/kg时, 这些指标的变化趋于平稳。饲料硒含量对存活率(SR)、饲料效率(FE)、体组成、肝体比(HSI)、脏体比(VSI)和肥满度(CF)都没有显著影响(P0.05)。在血清中谷胱甘肽过氧化物酶(GPX)活性、超氧化物歧化酶(SOD)活性和总抗氧化力(T-AOC)随着饲料硒含量的升高呈现先升高后稳定的趋势(P0.05), 并分别在饲料硒含量为0.44、0.44、0.16 mg/kg时达到最大值。肝脏中GPX活性、SOD活性、T-AOC、过氧化氢酶(CAT)活性和谷胱甘肽还原酶(GR)活性与血清中相应酶的活性有相同的趋势。在肝脏中谷胱甘肽硫转移酶(GST)活性随着饲料硒含量的升高呈现先降低后升高的趋势(P0.05), 并在饲料硒含量最高(0.96 mg/kg)时其活力取得最大值。以WG为评价指标, 得出大黄鱼幼鱼对饲料中硒的需求量为0.178 mg/kg。以全鱼和骨骼中硒含量、肝脏GPX活性为评价指标, 得出大黄鱼幼鱼对饲料中硒的最小需求量分别为0.575、0.387和0.440 mg/kg。       

硒胁迫对小球藻光合色素含量和生长的影响

50 mg/L的硒胁迫下,小球藻中β-胡萝卜素、类叶黄素、叶绿素(叶绿素a、叶绿素b)的含量先明显增加,之后逐渐下降;而在800 mg/L硒胁迫下,各种光合色素含量均明显下降;小球藻活体细胞在693 nm处出现叶绿素a的吸收峰,其吸收值在硒胁迫后明显减弱;在室温荧光发射光谱中,700 nm处的发射峰随着硒浓度的增加而显著下降;荧光激发光谱表明:硒胁迫使小球藻的能量传递受阻,传递效率降低;藻体中水溶性蛋白含量随着硒胁迫的增强而下降.等离子体原子发射光谱(ICP-AES)研究结果表明:随着硒浓度增加,藻体中Mg2 、Ca2 、K 和Na 含量呈明显降低趋势,而培养液中这些离子的浓度则不断增加.     

铜离子对钝顶螺旋藻完整细胞中光系统Ⅱ活性和藻胆体能量传递的影响

Cu2 抑制钝顶螺旋藻 ( Spirulina platensis)完整细胞中电子传递活性 ( H2 O→ MV) ,并抑制 PS 的放氧活性。低浓度的 Cu2 处理 ,使钝顶螺旋藻细胞中藻蓝蛋白荧光发射峰位置蓝移、发射强度改变 ,表明藻胆体中能量传递发生了变化。Cu2 处理纯化的藻蓝蛋白 ,使其在长波区 ( 61 6— 62 0 nm)吸收减小、荧光发射峰蓝移 ( 64 7nm→ 64 3nm) ;而变藻蓝蛋白不受影响 ,说明 Cu2 选择性作用于藻蓝蛋白。     

硒对镉胁迫下水稻幼苗生长及生理特性的影响

采用溶液培养 ,研究不同浓度的硒和镉处理对稻苗的株高、叶片干重、叶绿素、还原糖、叶片丙二醛含量以及保护酶 SOD、POD、CAT活性的影响。结果表明 ,镉胁迫下稻苗矮化 ,镉毒害使叶片失绿 ,干重降低 ,还原糖含量下降 ,叶片 MDA含量增加 ,POD活性增强 ,而 SOD、CAT活性降低 ;硒可减轻镉对水稻的毒害 ,表现为 :减轻镉胁迫对株高增加的抑制 ,提高叶绿素含量 ,增加叶片干物质积累 ,提高叶片还原糖含量 (Cd0 .5 mg/ L加 Se 0 .1 0～ 0 .5 0 mg/ L例外 ) ,降低 MDA含量与 POD活性 ,提高 SOD、CAT活性     

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。