紫外辐射对菹草成株表型可塑性及石芽的影响

菹草衰亡的原因一直是水体生态修复的研究热点,已有的研究认为强光照是促进菹草衰亡的关键因素,强光照中对动植物有害波段主要为UV-B波段,为此分别将菹草成株置于50、100、150、200μW/cm2剂量的UV-B辐射下,每日持续辐射6h(9:00—15:00),对照组接受的UV-B剂量为0,仅接受UV-A和光合有效辐射,监测菹草生长、形态状况、石芽形成及萌发等指标。结果表明,高剂量UV-B辐射能促进菹草成株的衰亡进程,即使暴露在低剂量UV-B辐射条件下,植株仍然衰亡;植株株高、节间距、叶面积、单株鲜重都受到UV-B辐射的抑制,且随UV-B辐射剂量增加,各项指标明显下降;UV-B辐射对菹草成株形成的石芽数量无显著影响,但形成的石芽随辐射剂量增加变态率增高,长度增加,宽度减少,石芽重量减轻,下一个生长季萌发率降低,萌发出二苗的比率降低,萌发苗各项生长指标随辐射剂量增加逐渐降低。因此,春末夏初UV-B辐射增强可能是导致菹草大批衰亡的重要原因。     

UV-B辐射对菹草成株叶绿素荧光参数的影响

以春末夏初南京地表实际UV-B剂量为参考,将菹草成株分别置于50、100、150和200μW·cm-2剂量的UV-B辐射下,测定其叶绿素荧光参数。结果表明:Fo、Fm在辐射早期随辐射剂量增加而递增,但后期随辐射剂量增加而递减;Fv/Fm、ΦPSII、NPQ随辐射剂量增加而递减。因此,菹草成株在遭遇UV-B辐射后,PSII反应中心出现可逆性失活或出现不易逆转的破坏,致使原初光能转换效率、电子传递速率下降,实际光化学效率降低,最终加速菹草衰亡。因此,春末夏初UV-B辐射增强可能是促进野外菹草大批衰亡的重要原因,但是否与其他环境因素之间存在联合作用机制,还需要进一步研究。     

三角褐指藻和小角毛藻对UV-B辐射增强的生理生化响应

通过实验生态学和生物化学的方法,研究了UV-B辐射对三角褐指藻和小角毛藻的生长、叶绿素a、类胡萝卜素、丙二醛、可溶性蛋白含量和抗氧化物酶活性的影响。结果表明:(1) UV-B辐射增强抑制了2种微藻的生长,低剂量(0.75J/m²)UV-B辐射对三角褐指藻的生长具有一定刺激作用。(2) 三角褐指藻的叶绿素a含量随辐射剂量的增加先上升后下降,小角毛藻chl-a含量缓慢下降。2种微藻MDA含量随UV-B辐射剂量的增加而升高。(3) 随着辐射剂量的增加,三角褐指藻可溶性蛋白含量先稍有升高后较快下降。小角毛藻可溶性蛋白含量始终呈下降趋势。(4) UV-B辐射增强使2种微藻的SOD 、POD和CAT活性先升高后下降,小角毛藻的酶活性变化相对稳定。     

UV-B增加对玉米花粉抗氧化能力及授粉后籽粒发育的影响

在玉米散粉期,收集花粉进行UV-B辐射增强处理后进行人工授粉研究,结果表明,随着UV-B辐射时间的增加,玉米花粉的SOD、POD和CAT活性都呈明显下降的趋势,而MDA含量则呈相应上升的趋势;玉米每穗粒数与花粉抗氧化酶活性呈正相关、与MDA含量呈负相关关系,并随UV-B辐射时间延长呈下降趋势,且辐射超过2h后下降达到显著水平;玉米百粒重随UV-B辐射时间的延长明显下降,但辐射花粉1~2h对其无显著影响;UV-B辐射花粉对籽粒的可溶性糖、淀粉、脂肪及粗蛋白含量等营养成分无显著影响。     

温度和紫外辐射胁迫对西藏飞蝗抗氧化系统的影响

为探讨西藏飞蝗(Locusta migratoria tibetensis Chen)对环境的适应机制,报道了温度和紫外辐射胁迫对西藏飞蝗抗氧化系统影响。以西藏飞蝗成虫为试材,研究5—20℃低温、30—45℃高温胁迫和紫外线辐射对其抗氧化酶活性和膜脂过氧化物丙二醛(MDA)含量的影响。在5—20℃低温胁迫下,成虫体壁和消化道超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性及丙二醛(MDA)含量分别随温度降低而升高;在30—35℃高温胁迫下,成虫SOD、POD和CAT活性分别随温度升高而升高,当温度超过35℃时,3种氧化酶活性均下降。长波紫外辐射(UV-A)和中波紫外辐射(UV-B)对处理后24h和72h成虫的SOD活性的影响大于可见光,在UV-A、UV-B和可见光3种光波长处理下,成虫的POD和CAT活性随光照时间的延长而增加,其中UV-B对两种酶活性影响大于UV-A和可见光,表现为UV-B处理组>UV-A处理组>可见光处理组;UV-A和UV-B处理能导致虫体体壁MDA含量明显升高,且对脂质过氧化的诱导存在时间效应;雌虫体壁、雌虫消化道、雄虫体壁和雄虫消化道的MDA含量分别在UV-B72h、UV-A72h、UV-A72h和UV-B72h达最大值0.72、0.88、0.66和0.94 nmol/g鲜重。在20—5℃低温胁迫下,西藏飞蝗成虫抗氧化酶活性升高,能较好的保护自身免遭活性氧自由基的伤害;西藏飞蝗对高温忍耐力差,在高于35℃高温胁迫下,成虫SOD、POD、CAT活性均下降;在长波和中波紫外辐射下,西藏飞蝗抗氧化酶活性显著升高,是西藏飞蝗对紫外线辐射强度大的青藏高原的一种重要适应。     

增强UV-B辐射对麻花艽叶片的抗氧化酶的影响

以青藏高原的特有植物麻花艽为材料,研究麻花艽叶片抗氧化酶系统对增强UV-B辐射的响应。结果表明：在UV-B处理初期,麻花艽叶片SOD、POD的酶活性都能增加,但随着处理时间的延长,SOD、POD的活性呈现下降趋势。麻花艽叶片CAT的酶活性在UVB处理后下降明显,但作为清除叶绿体中H2O2的关键酶AP的酶活性表现为明显地增加趋势,说明在对麻花艽叶片增强UV-B辐射反应中AP起有着重要作用。MDA的含量随UV-B处理时间延长而增加,表明UV-B降低了细胞内活性氧自由基的清除能力,膜脂过氧化作用加剧,导致了对麻花艽叶片的伤害效应。     

UV-B辐射对雨生红球藻光合特性和虾青素含量的影响及其响应

实验研究了不同强度的UV-B(280-320 nm)辐射对雨生红球藻(Haematococcus pluvialis)的光合活性、生物量、色素含量、活性氧(ROS)含量和抗氧化酶活性等的影响, 以探讨利用UV-B辐射诱导虾青素生物合成增强的可能性。结果发现, 经UV-B辐射处理后,雨生红球藻的光合活性降低、生物量增长被抑制。UV-B辐射对叶绿素影响不大, 但会改变细胞的类胡萝卜素和虾青素含量:0.1和0.3 W/m2强度的UV-B辐射使细胞中的这两种色素含量升高, 0.5 W/m2组的色素含量短暂升高后恢复到对照水平。中低强度的UV-B可以促进雨生红球藻单细胞虾青素含量的增加, 但由于其对细胞生长的抑制作用, 并不能使虾青素大量积累。随辐射时间延长, 细胞内ROS含量未明显增加,但抗氧化酶(过氧化氢酶和超氧化物歧化酶)活性下降, 雨生红球藻可能主要依靠虾青素来淬灭ROS。以上结果表明, UV-B辐射对雨生红球藻的主要生理生化过程有抑制作用, UV-B辐射既可以诱导虾青素的合成又会消耗一部分虾青素, 对虾青素含量的影响与其强度有关, 而利用虾青素来清除细胞内的ROS可能是雨生红球藻抵御这种不利环境条件的最重要的途径。       

UV-B辐射对仙客来的生理效应

通过室内模拟试验,研究了不同强度UV-B辐射(10μW/cm2和20μW/cm2)对仙客来(Cyclamen persicum Mill)生理的影响。结果表明:(1)UV-B辐射的增加对仙客来叶片光合色素的含量具有影响;(2)叶片质膜透性随UV-B辐射强度的增加而增加,随UV-B辐射时间的延长而增加;(3)叶片类黄酮含量随UV-B辐射强度的增加而增加,且在40d时达到最大值;(4)增强UV-B辐射下,仙客来花瓣中的花青素含量增加。     

CO2浓度倍增减轻UV-B辐射对大棚番茄的抑制作用研究

在CO2浓度倍增(700 μmol·mol-1)条件下,以5个不同剂量的UV-B辐射对大棚番茄的光合作用及SOD、POD、CAT酶活性的影响进行了研究.结果表明CO2倍增能够明显提高番茄叶绿素含量、净光合速率和抗氧化酶活性.在CO2倍增条件下,低剂量UV-B辐射(<1.163 kJ·m-2·d-1)可以刺激番茄叶片叶绿素含量升高,抗氧化酶活性升高,与CO2的正效应有叠加现象,但对光合作用的影响不大;高剂量的UV-B(>1.163 kJ·m-2·d-1)辐射使植株的叶绿素含量、净光合速率和抗氧化酶活性降低,对植物产生胁迫作用,CO2倍增与UV-B辐射复合处理可以减弱和部分抵消这种抑制作用.     

CaCl_2对UV-B辐射下菠菜叶片光合特性的影响

以"丹麦旺盛菠菜"为材料,通过UV-B和CaCl2复合处理,测定光合色素含量、Hill反应活力、叶绿素荧光、MDA含量和抗氧化酶活性等参数,探讨了CaCl2对UV-B辐射下菠菜叶片电子传递链和光合膜酶保护系统的影响。结果表明,UV-B处理下,光合色素含量、chl/car、类囊体膜上PSII潜在活性(Fv/Fo)、光化学淬灭系数(qP)、非光化学淬灭系数(qN)、PSII光量子产量(ΦPSⅡ)、原初光能转化效率(Fv/Fm),以及Hill反应活力等降低,chla/chlb和MDA含量升高;喷洒CaCl2可不同程度缓解UV-B的伤害。不同处理下,POD、SOD和CAT活性的变化呈现补偿效应。UV-B强度与菠菜叶片PSII功能受损程度呈正相关,CaCl2则主要通过提高chlb含量、类囊体膜上的光量子产量和POD活性,以缓解伤害。重度UV-B辐射下,CaCl2使chlb含量显著提高可能是导致PSII捕光效率提高的重要因素。     

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.     

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.     

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.     

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.     

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。     

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.     

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.