高等植物的命脉—维管系统之谜

本文是将要出版的《植物生理与分子生物学》一书中的一篇,现征得作者同意先行发表于此(限于版面,文献从略);同时将殷宏章教授为该书写的序言也发表出来(见第62页),以飨读者。     

茄子幼苗初生维管系统的解剖学研究

对茄子幼苗的初生维管系统以子叶节区理论为指导,进行解剖学研究。经研究表明,其初生维管组织的器官间过渡形式,属顶枝伸长型的子叶节区。子叶节区下部较短,中部较长,故只有一个极短的子叶节区－根过渡区和上胚轴苗区,与子叶节区之间的维管组织连接区,其维管组织的转化,主要存在于子叶节区中部与子叶之间。     

砧木与接穗间的电波传递

利用嫁接系统研究植物电波的传递表明：（１）无论砧木和接穗共质体连通与否,也无论在嫁接面上加琼脂与否,电波（ＥＷ）均能沿砧木向接穗传递;（２）砧木和接穗共质体连通之前,无论在嫁接面上加琼脂与否,ＥＷ不能沿接穗向砧木传递,砧木和接穗产生的愈伤组织细胞突破隔离层,互相嵌合,产生次生胞间连丝之后,ＥＷ可沿接穗传至砧木;（３）将枝条蒸腾流倒转后进行嫁接,ＥＷ可沿接穗（形态学上部,即插入水中部分）传至砧木（形态学下部）,但不能沿砧木传至接穗。     

家黑种草幼苗初生维管系统的解剖学研究

家黑种草幼苗子叶节区中部存在中始式二原型管状中柱阶段的事实,就足以说明,Ｎａｍｂｏｏｄｉｒｉ和Ｂｅｃｋ（１９６８ａ,ｂ,ｃ）的理一即认为在前裸子植物一种子植物的初生维管系统中不存在管状中柱阶段,从而主张种子植物在起源上与真蕨类毫无亲缘关系的理论是不够慎重的,作者信息,随着管状中柱阶段的不同断发现,就预言它产两者之间,在系统发育的守,可能有关个“共同的祖先”。     

辽藁本(Ligusticum jeholense)幼苗初生维管系统的发育

应用整体透明和石蜡连续切片等方法,对辽藁本幼苗初生维管系统的发育进行了观察。结果表明：该幼苗的轴向器官中,以子叶节区下部的初生维管系统先建立,向下发育形成了下胚轴和根的维管系统;再向上通过子叶节区中、上部的分生组织性组织与第1片真叶的叶迹相连;上胚轴一苗的维管系统向下发育与子叶迹相连,至此构成了该幼苗完整、连续的初生维管系统。此外,对幼苗侧生器官子叶片的三出一叉状脉的形成进行了观察,认为该叶脉序属于原始脉序类型。     

3属4种罂粟科植物幼苗初生维管系统的结构

罂粟科属间演化关系一直存在争议。本文以罂粟科罂粟属的虞美人（Papaver rhoeas）和东方罂粟（Papaver orientale）、白屈菜属的白屈菜（Chelidonium majus）以及紫堇属的地丁草（Corydalis bungeana）为材料,应用整体透明和石蜡连续切片的方法,在明场显微镜和偏光显微镜下对其幼苗期的结构及发育进行了观察。结果表明,3属植物幼苗子叶节区下部存在的单中柱类型各异：罂粟属为外始式二原型圆形单中柱,白屈菜属为外始式二原型近圆形单中柱,紫堇属为外始式二原型“S”形单中柱。3属植物的子叶脉序也存在区别：虞美人和东方罂粟具单一叶脉,无叶隙;白屈菜为环结曲行羽状脉;地丁草为基出完全顶聚脉。根据上述幼苗初生维管系统的结构,认为3属中罂粟属较为原始,白屈菜属较为进化,紫堇属更为进化。     

3属4种罂粟科植物幼苗初生维管系统的结构

罂粟科属间演化关系一直存在争议。本文以罂粟科罂粟属的虞美人（Papaver rhoeas）和东方罂粟（Papaver orientale）、白屈菜属的白屈菜（Chelidonium majus）以及紫堇属的地丁草（Corydalis bungeana）为材料,应用整体透明和石蜡连续切片的方法,在明场显微镜和偏光显微镜下对其幼苗期的结构及发育进行了观察。结果表明,3属植物幼苗子叶节区下部存在的单中柱类型各异：罂粟属为外始式二原型圆形单中柱,白屈菜属为外始式二原型近圆形单中柱,紫堇属为外始式二原型“S”形单中柱。3属植物的子叶脉序也存在区别：虞美人和东方罂粟具单一叶脉,无叶隙;白屈菜为环结曲行羽状脉;地丁草为基出完全顶聚脉。根据上述幼苗初生维管系统的结构,认为3属中罂粟属较为原始,白屈菜属较为进化,紫堇属更为进化。     

梓树幼苗初生维管系统的解剖学研究

根据子叶节区理论对梓树幼苗初生维管系统进行了解剖学研究。结果表明:梓树幼苗的子叶节区较长,自上到下都有髓的存在,为向基移位型。子叶节区下部具有中始式四原型管状中柱,在子叶节区中部的原生木质部处一分为二,逐渐形成具有8枚外韧维管束的中柱结构;在子叶节区上部,组成短轴的2枚维管束各自一分为三,逐渐形成真中柱的雏形,与上胚轴顶端分生性组织分化形成的内始式真中柱相连,至此,子叶节区发育完成。子叶为单隙三迹。     

局部灼伤对小麦幼苗外源茉莉酸吸收与运转的影响

采用示踪技术探索了3H-JA的运输和分配规律及其受伤害胁迫的影响.外源3H-JA能够在小麦幼苗体内向上和向下运输,局部灼伤其运输与分配都发生了改变.从小麦根系饲喂的3H-JA,在植株内的分布量依序为根＞茎＞叶,时间较长(4h)时分配于心叶的3H-JA大大增加.当叶片受到局部灼伤时3H-JA向地上部的输出量减少;但局部灼伤可加快由心叶饲喂的3H-JA的向下运输,改变3H-JA在小麦幼苗各部位的分配比率.心叶饲喂短时间(5min)时,3H-JA主要积累在受到伤胁迫的展开叶(第2叶)中.向展开叶(第2叶)饲喂的3H-JA向下运输的速率高于向上运输的速率.推测JA运输及分配的变化可能在植株的防御反应中起重要作用.     

机械伤害和外施茉莉酸对巴西橡胶树次生乳管分化的局部效应及其与茉莉酸分布的关系

采用同位素示踪技术和实验形态学的方法揭示茉莉酸在木本植物巴西橡胶树(Hevea brasiliensis Mull.Arg.)中的分布和运输的特点,并分析其与机械伤害和外施茉莉酸对巴西橡胶树次生乳管分化的诱导效应之间的关系.外施的茉莉酸进入体内后,在较长时间内大部分集中在施用部位.机械伤害阻止外施的茉莉酸进入体内,同时,又使进入的茉莉酸阻滞在受伤部位的附近.与茉莉酸在草本植物中可以向上和向下运输的情况不同,茉莉酸在木本植物巴西橡胶树中主要是向下运输的.机械伤害和外施茉莉酸对巴西橡胶树次生乳管分化的诱导效应是局部的,只在受伤和施用茉莉酸部位的树皮中诱导次生乳管的形成.机械伤害削弱外源茉莉酸对次生乳管分化的诱导效应,这与机械伤害阻止外源茉莉酸进入有关.研究结果表明,体内高水平的茉莉酸是诱导巴西橡胶树次生乳管分化所必需的.     

机械伤害和外施茉莉酸对巴西橡胶树次生乳管分化的局部效应及其与茉莉酸分布的关系

采用同位素示踪技术和实验形态学的方法揭示茉莉酸在木本植物巴西橡胶树(Hevea brasiliensis Mull．Arg．)中的分布和运输的特点,并分析其与机械伤害和外施茉莉酸对巴西橡胶树次生乳管分化的诱导效应之间的关系。外施的茉莉酸进入体内后,在较长时间内大部分集中在施用部位。机械伤害阻止外施的茉莉酸进入体内,同时,又使进入的茉莉酸阻滞在受伤部位的附近。与茉莉酸在草本植物中可以向上和向下运输的情况不同,茉莉酸在木本植物巴西橡胶树中主要是向下运输的。机械伤害和外施茉莉酸对巴西橡胶树次生乳管分化的诱导效应是局部的,只在受伤和施用茉莉酸部位的树皮中诱导次生乳管的形成。机械伤害削弱外源茉莉酸对次生乳管分化的诱导效应,这与机械伤害阻止外源茉莉酸进入有关。研究结果表明,体内高水平的茉莉酸是诱导巴西橡胶树次生乳管分化所必需的。     

ESI-MS/MS方法检测拟南芥膜脂分子对机械伤害的响应

利用一种灵敏的、基于ESI-MS／MS（electrospray ionization tandem mass spectrometry）的脂类组学方法,测定了机械伤害诱导的拟南芥6种磷脂（phosphohpids）、2种糖脂（glycolipids）、3种溶血磷脂（lysophospholipids）和约120种脂类分子的变化,探索了膜脂响应机械伤害的基本趋势。结果表明,机械伤害后磷脂酸（phosphatidic acid,PA）和3种溶血磷脂显著升高,而叶绿体膜上的糖脂减少;在测量的1小时范围内,不同脂类水解产生的磷脂酸分子的增加速度和强度不同,反映出它们经历了不同的生化过程。具体表现为：（1）叶绿体膜脂磷脂酰甘油（phosphatidylglycero,PG）分子34：4 PG水解的产物磷脂酸分子34：4 PA的积累速度明显慢于其它磷脂酸分子;（2）磷脂酸分子34：6 PA仅有少量的积累,其可能是由叶绿体膜脂单半乳糖二酰甘油（monogalactosyldiacylglycerol,MGDG）。分子34：6 MGDG和双半乳糖二酰甘油（digalactosyldiacylglycerol,DGDG）分子34：6 DGDG水解产生,然而这两种糖脂含量明显下降,说明它们有可能还参与了其它的反应。脂类的摩尔百分组成没有剧烈的变化。     

生姜呈香部位气相色谱指纹图谱共有峰的GC/MS分析

采用气相色谱-质谱联机技术,对不同居群生姜的指纹图谱部分共有峰进行了定性分析,初步鉴定了其中的20个成分。     

Selective blockade of the delayed rectifier potassium current by tacrine in Drosophila

Tetrahydroaminoacridine (tacrine) is an anticholinesterase agent used in the treatment of Alzheimer's disease. Its effectiveness against dementia is attributed to its inhibition of acetylcholine breakdown in the synaptic cleft. Tacrine has also been shown to block ionic currents, including many types of potassium (K⁺) currents, calcium currents, and sodium currents. However, the physiologic significance of this blockade, especially with respect to its effectiveness against Alzheimer's disease, is not clear because of relatively high (several hundred micromolar to millimolar) concentrations of tacrine employed in many studies of channel blockade, and because it blocks several types of currents. A complete mutational and pharmacologic resolution of ionic currents in the larval muscles of Drosophila allowed us to examine the selectivity of tacrine's effects at very low concentrations. At concentrations as low as 10 μM, tacrine selectively blocked the delayed rectifier K⁺ current without affecting the three other K⁺ currents or the calcium channel current in these cells. It also increased the duration of the action potentials significantly. An interesting aspect of tacrine's selectivity is that the current blocked by it is the quinidine-sensitive delayed rectifier K⁺ current rather than the 4-aminopyridine (4-AP)-sensitive transient K⁺ current. This is in contrast to the generally emphasized structural relationship between tacrine and 4-AP. Since tacrine is structurally related to quinidine as well, these observations suggest a structural basis for the selectivity of tacrine, 4-AP, and quinidine for specific K⁺ channels. Furthermore, the data are consistent with the possibility of increased neurotransmitter release, due to prolonged presynaptic action potentials, acting synergistically with the anticholinesterase activity of tacrine to increase its therapeutic effectiveness. © 1997 John Wiley & Sons, Inc. J Neurobiol 32: 1–10, 1997.     

Alteration of the action potential of tissue cultured neuronal cells by growth in the presence of a polyunsaturated fatty acid

The effects of alterations in membrane phospholipid fatty acid composition on the excitability of neuroblastoma × glioma hybrid cells, clone NG108-15, were examined using intracellular recording techniques. Cells were grown in the presence of arachidonate (20:4) added to the culture medium as a complex with bovine serum albumin. Exposure of the cells to 20:4 for 3–21 days produced a 40% decrease in the maximum rate of rise of the action potential (dV/dt) with a small change in its amplitude. The resting membrane potential and passive properties of the cells were unaffected. An effect of 20:4 was not observed until 24 hr after treatment and increased over the next 2 days. The phospholipid content of 20:4 and its metabolite 22:4 increased from 6.9% to 25.3% of total fatty acids during approximately the same time span. It is concluded that the action potential dV/dt can be altered by changes in membrane lipid composition.     

刺激迷走神经引起的鲫鱼Mauthner细胞顺向激活

目的 :研究迷走神经感觉传入信息对Mauthner细胞 (M细胞 )兴奋性的影响。方法 :刺激鲫鱼迷走神经 ,并运用微电极穿刺技术记录鲫鱼M细胞胞内电位变化。结果 :在M细胞胞内记录到分级的、复合的兴奋性突触后电位(EPSP) ,分为第一成分和第二成分。随着刺激强度的增大 ,EPSP的幅度增大 ,反应持续时间延长。当刺激强度足够大时 ,在第一成分或第二成分的基础上可爆发动作电位。结论 :①刺激迷走神经可引起M细胞顺向激活 ,这与以往的观点不同 ;②从迷走神经到M细胞的感觉传入通路可能由含有兴奋性和抑制性成分的不同种类的神经链构成 ,M细胞的兴奋性取决于兴奋和抑制之间的相互关系     

Seasonal variation in hydrochloric acid, malic acid, and calciumions secreted by the trichomes of chickpea (Cicer arietinum)

A novel experimental set-up and method of recording of electrical potential differences in plants have been developed which enable continuous, 8-channel monitoring of electrical activity over extended periods of time using inserted, extracellular electrodes. The investigations were carried out on 21- to 23-day-old Helianthus annuus plants, and spontaneously-generated action potentials were recorded during monitoring sessions lasting for 3 days and nights. Characteristics of these spontaneous action potentials were elaborated, adopting as parameters their typical form, amplitude, duration, velocity, direction, and distance of propagation and frequency of occurrence in morphologically different parts of the plant, Variability, similarities, and interdependence of the above parameters in individual plants and in a group of 15 plants were determined. A hypothesis concerning propagation of action potentials in plants along specific impulse-propagating 'columns' is discussed. The frequency of generated impulses is highest at night and lowest in the day and also displays an apparent 24-h rhythm. Presumably this mechanism is under both endogenous and exogenous control and may be partly dependent on a biological clock.     

Nonselective Suppression of Voltage-gated Currents by Odorants in the Newt Olfactory Receptor Cells

Effects of odorants on voltage-gated ionic channels were investigated in isolated newt olfactory receptor cells by using the whole cell version of the patch–clamp technique. Under voltage clamp, membrane depolarization to voltages between −90 mV and +40 mV from a holding potential (V_h) of −100 mV generated time- and voltage-dependent current responses; a rapidly (< 15 ms) decaying initial inward current and a late outward current. When odorants (1 mM amyl acetate, 1 mM acetophenone, and 1 mM limonene) were applied to the recorded cell, the voltage-gated currents were significantly reduced. The dose-suppression relations of amyl acetate for individual current components (Na⁺ current: I_Na, T-type Ca²⁺ current: I_Ca,T, L-type Ca²⁺ current: I_Ca,L, delayed rectifier K⁺ current: I_Kv and Ca²⁺-activated K⁺ current: I_K(Ca)) could be fitted by the Hill equation. Half-blocking concentrations for each current were 0.11 mM (I_Na), 0.15 mM (I_Ca,T), 0.14 mM (I_Ca,L), 1.7 mM (I_Kv), and 0.17 mM (I_K(Ca)), and Hill coefficient was 1.4 (I_Na), 1.0 (I_Ca,T), 1.1 (I_Ca,L), 1.0 (I_Kv), and 1.1 (I_K(Ca)), suggesting that the inward current is affected more strongly than the outward current. The activation curve of I_Na was not changed significantly by amyl acetate, while the inactivation curve was shifted to negative voltages; half-activation voltages were −53 mV at control, −66 mV at 0.01 mM, and −84 mV at 0.1 mM. These phenomena are similar to the suppressive effects of local anesthetics (lidocaine and benzocaine) on I_Na in various preparations, suggesting that both types of suppression are caused by the same mechanism. The nonselective blockage of ionic channels observed here is consistent with the previous notion that the suppression of the transduction current by odorants is due to the direst blockage of transduction channels.