细胞松弛素B对蚕豆气孔运动的影响

以蚕豆叶片下表皮条为材料,研究了微丝在气孔运动中的作用。利用肌动蛋白纤丝专一性抑制剂──细胞松弛素Ｂ（ＣＢ）预处理后,再用诱导气孔运动的因子处理表皮条,在显微镜下观测气孔孔径的变化。结果显示,用ＣＢ处理开放或关闭状态气孔,其开度均不发生变化;ＣＢ处理使微丝解聚,气孔运动被抑制;且ＣＢ处理后气孔的运动是可以恢复的。实验进一步表明,开放气孔经１０ｍｇ／Ｌ的ＣＢ预处理后,ＡＢＡ、Ｃａ２＋及暗诱导气孔关闭的作用均不同程度地受到抑制,推测微丝可能参与ＡＢＡ、Ｃａ２＋及暗诱导的气孔关闭过程;关闭气孔经１０ｍｇ／Ｌ的ＣＢ预处理后,Ｋ＋和（或）光诱导气孔开放的作用受到抑制,推测微丝可能参与光及Ｋ＋诱导的气孔开放过程。     

乙酰胆碱对蛇运动神经末梢离子通道活动的反馈调节

由研究乙酰胆碱受体激动剂和阻断剂的作用提出,在脊椎动物运动神经末梢存在着对乙酰胆碱（ＡＣｈ）释放的反馈调节。神经末梢的离了通道在递质释放中有重要作用。本文是利用周膜下记录技术。研究ＡＣｈ对蛇运动神经末梢离子通道调节作用的报告。（１）２ｍｍｏｌ／ＬＡＣｈ明显抑制依钙Ｋ流（ＩＫ,Ｃａ）此效应与３ｍｍｏｌ／ＬＴＥＡ的相似。由于ｎＡＣｈＲ激动剂尼古丁（２ｍｍｏｌ／Ｌ） 不影响Ｉｋ,ｆ和ＩＫ,Ｃdisplay stat     

麻醉剂氟烷对心脏毒蕈碱型钾通道的影响

神经递质乙酰胆碱（ＡＣｈ）调节心脏功能最重要的离子通道就暗毒蕈碱型钾通道（ｉＫ,ＡＣｈ）,该通道由ＡＣｈ经鸟苷酸调节蛋白（Ｇ蛋白）的βγ亚单位而激活。本实验彩全细胞膜片箝方法,观察了麻醉药氟烷对豚鼠心房肌细胞ｉＫ,ＡＣｈ的影响。氟烷对ｉＫ,ＡＣｈ电流具抑制效应,灌注之后可使ＡＣｈ激活的ｉＫ,ＡＣｈ速率减慢,峰植下降。但其抑制ｉＫ,ＡＣｈ的程度依激活方式而异：经正常激活途径,即由ＡＣｈ激活毒蕈碱Ｍ样     

气孔蒸腾中保卫细胞原生质的调控作用

气孔运动的机理一般公认为保卫细胞的渗透调节。作者所在研究小组近几年的工作表明：动物神经递质乙酰胆碱参与气孔运动的调节；植物细胞骨架微管、微丝在气孔运动中起重要作用。因面提出保卫细胞原生质在气孔蒸腾中的气孔蒸腾中的作用值得进一步研究。     

钾和菊酸钠诱导的离体黄瓜子叶生根过程中内源IAA和ABA含量变化

１３．４ｍｍｏｌ／Ｌ ＫＣｌ和０．６ｍｍｏｌ／Ｌ的菊酸钠诱导离体黄瓜子叶生根过程中,子叶中内源ＩＡＡ含量明显增加,菊酸钠处理的增加趋势高于ＫＣｌ处理;ＡＢＡ含量则显著下降,ＫＣｌ和菊酸钠处理的分别在２４ｈ和８ｈ达到最低,各处理的ＩＡＡ／ＡＢＡ值均明显增加。     

硒引起冠状动脉平滑肌的舒张和细胞电位的降低

硒是对机体机能有重要影响的一种必需的微量元素。本工作分别应用豚鼠冠状动脉血管条张力记录的方法及平滑肌细胞内微电极记录膜电位的方法，研究了硒对平滑肌的作用，结果表硒能引起冠状动脉平滑舒张及细胞电位去极化，而且均为剂量依赖式。硒对ＫＣｌ及ＡＸｈ引发收缩产生的抑制作用表现为剂量反应曲线的右移。膜电位和细胞内记录表明硒可使ＫＣｌ引起的去极化作用加强以及使ＡＣｈ引起的超极化作用减弱。     

乙酰胆碱在调节植物行为中的作用

动物体内,乙酰胆碱（ＡＣｈ）是一种重要的神经递质。它参与神经突触之间以及神经突触与肌肉之间的信号传递。近些年来,ＡＣｈ和胆碱能系统的其它成员在植物界都已找到并且分布很广。它们在植物的多种行为（生长、发育、运动、代谢等）上发挥着类似激素的调节作用。Ｄａｒｗｉｎ曾提出有些敏感植物执行的快速运动不是膨压运动所能胜任,认为由电波传递与原生质收缩来承担。近来还有人提出：植物体内的电波传递与原生质收缩要有ＡＣｈ这神经递质参加。我室近几年来在丝瓜的向触性快速运动以及甘薯的气孔运动的机理研究中给这两项建议得出确切的实验证明。     

盐分对碱蓬幼苗离子含量,甜菜碱水平和BADH活性的效应

研究了盐生植物碱蓬（Ｓｕａｅｄａ ｓａｌｓａ）生长在不同浓度的ＮａＣｌ和ＫＣｌ溶液中体内Ｎａ＋ 、Ｋ＋ 含量、甜菜碱水平和甜菜碱醛脱氢酶（ＢＡＤＨ）活性的动态变化。ＮａＣｌ处理９６ 小时后,碱蓬地上部Ｋ＋ 含量低于对照,而Ｎａ＋ 明显高于对照,并分别随外界盐度增加而升、降;ＫＣｌ处理的植株,Ｋ＋ 、Ｎａ＋ 含量变化与ＮａＣｌ处理的相反;甜菜碱水平和ＢＡＤＨ 活性随外界ＮａＣｌ浓度增加而升高,甜菜碱水平随处理时间延长而增大,ＫＣｌ对甜菜碱水平和ＢＡＤＨ 活性的效应类似ＮａＣｌ。证明ＮａＣｌ和ＫＣｌ均能促进盐生植物碱蓬体内甜菜碱的积累,初步证明ＢＡＤＨ 与甜菜碱的积累有关     

神经生长因子对神经损伤后运动终板再生影响的研究——酶组织化学和超微结构观察

本研究采用定位、定量方式钳夹兔右侧坐骨神经,ＮＧＦ组动物于神经损伤处局部喷布蛇毒神经生长因子（ｎｅｒｖｅｇｒｏｗｔｈｆａｃｔｏｒ,ＮＧＦ）,对照组动物于同部位给予等量生理盐水。对胫骨前肌中的红肌、白肌和中间型肌纤维运动终板乙酰胆碱酯酶（ＡＣｈＥ）活性和超微结构改变进行观察。结果表明,神经损伤早期,ＡＣｈＥ活性持续下降,超微结构显示逐渐变性。第４周末,ＮＧＦ组运动终板ＡＣｈＥ活性和超微结构恢复正常。第８周末,对照组运动终板酶活性和超微结构才基本恢复正常。本研究结果提示,周围神经损伤后,外源性ＮＧＦ能促进运动神经元轴突再生,最终促进运动终板结构和功能恢复     

三种蜘蛛丝蛋白组成分析

本文应用高压液相色谱（ＨＰＬＣ）法分析了岳麓山的大腹园蛛Ａｒａｎｅｕｓ ｖｅｎｔｒｉｃｏｓｕｓ（Ｃ．Ｋｏｃｈ,１８７８）,机敏漏头蛛Ａｇｅｌｅｎａ ｄｉｆｆｉｃｌｉｓ （Ｆｏｘ,１９３７）,白额巨蟹蛛Ｈｅｔｅｒｏｐｏｄａ ｖｅｎａｔｏｒｉａ （Ｌｉｎｎａｅｕｓ,１７５７）的丝蛋白的氨基酸组成,以ＳＤＳ－ＰＡＧＥ法测定了大腹园蛛不同丝腺体的未成丝的可溶性丝蛋白的分子量。实验结果表明蛛丝蛋白中占优势的     

微管在气孔运动中的作用

用植物微管专一性解聚剂甲基胺草磷(APM)预处理蚕豆(Vicia faba L.)下表皮,再用诱导气孔运动的因子处理,在显微镜下观察气孔孔径的变化。结果显示,用50mg/L APM预处理开放或关闭状态气孔,虽胞质微管被解聚,但气孔孔径没有发生明显的变化,表明胞质微管与开放或关闭状态气孔的维持无关;而去掉APM后,CaCl_2可在4h内诱导气孔关闭,气孔的运动功能又可恢复。进一步的研究表明,开放气孔经APM预处理60min后,再用ABA、Ca~(2 )及暗处理均不能诱导气孔关闭,表明微管可能参与了ABA、Ca~(2 )及暗诱导的气孔关闭过程;关闭气孔经50mg/L APM预处理后,光诱导气孔开度较不经 APM处理的有明显差异,且随着APM预处理时间和浓度的变化,气孔开放程度亦不同,表明微管也参与了光诱导的气孔开放过程。     

Actin Filaments in Mature Guard Cells Are Radially Distributed and Involved in Stomatal Movement

Stomatal movements, which regulate gas exchange in plants, involve pronounced changes in the shape and volume of the guard cell. To test whether the changes are regulated by actin filaments, we visualized microfilaments in mature guard cells and examined the effects of actin antagonists on stomatal movements. Immunolocalization on fixed cells and microinjection of fluorescein isothiocyanate-phalloidin into living guard cells of Commelina communis L. showed that cortical microfilaments were radially distributed, fanning out from the stomatal pore site, resembling the known pattern of microtubules. Treatment of epidermal peels with phalloidin prior to stabilizing microfilaments with m-maleimidobenzoyl N-hydroxysuccimimide caused dense packing of radial microfilaments and an accumulation of actin around many organelles. Both stomatal closing induced by abscisic acid and opening under light were inhibited. Treatment of guard cells with cytochalasin D abolished the radial pattern of microfilaments; generated sparse, poorly oriented arrays; and caused partial opening of dark-closed stomata. These results suggest that microfilaments participate in stomatal aperture regulation.     

Microtubules are essential for guard-cell function in Vicia and Arabidopsis

Radially arranged cortical microtubules are a prominent feature of guard cells. Guard cells expressing GFP-tubulin showed consistent changes in the appearance of microtubules when stomata opened or closed. Guard cells showed fewer microtubule structures as stomata closed, whether induced by transfer to darkness, ABA, hydrogen peroxide, or sodium hydrogen carbonate. Guard cells kept in the dark (closed stomata) showed increases in microtubule structures and stomatal aperture on light treatment. GFP-EB1, marking microtubule growing plus ends, showed no change in number of plus ends or velocity of assembly on stomatal closure. Since the number of growing plus ends and the rate of plus-end growth did not change when microtubule structure numbers declined, microtubule instability and/or rearrangement must be responsible for the apparent loss of microtubules. Guard cells with closed stomata showed more cytosolic GFP-fluorescence than those with open stomata as cortical microtubules became disassembled, although with a large net loss in total fluorescence. Microtubule-targeted drugs blocked guard-cell function in Vicia and Arabidopsis. Oryzalin disrupted guard-cell microtubules and prevented stomatal opening and taxol stabilized guard-cell microtubules and delayed stomatal closure. Gas exchange measurements indicated that the transgenes for fluorescent-labeled proteins did not disrupt normal stomatal function. These dynamic changes in guard-cell microtubules combined with our inhibitor studies provide evidence for an active role of microtubules in guard-cell function.     

The function of guard cells does not require an intact array of cortical microtubules

The development of stomatal guard cells is known to require cortical microtubules; however, it is not known if microtubules are also required by mature guard cells for stomatal function. To study the role of microtubules in guard cell function, epidermal peels of Vicia faba were subjected to conditions known to open or close stomata in the presence or absence of microtubule inhibitors. To verify the action of the inhibitors, microtubules in appropriately treated epidermal peels were localized by cryofixation followed by freeze substitution and embedding in butyl-methyl methacrylate. Mature guard cells had a radial array of microtubules, focused toward the thick cell wall of the pore, and the appearance of this array was the same for stomata remaining closed in darkness or induced to open by light. Treatment of epidermal peels with 1 mM colchicine for 1 h depolymerized nearly all cortical microtubules. Measurements of stomatal aperture showed that neither 1 mM colchicine nor 20 M taxol affected any of the responses tested: remaining closed in the dark, opening in response to light or fusicoccin, and closing in response to calcium and darkness. We conclude that intact microtubule arrays are not invariably required for guard cell function.     

Microtubules of guard cells are light sensitive

Guard cells of stomata are characterized by ordered bundles of microtubules radiating from the ventral side toward the dorsal side of the cylindrical cell. It was suggested that microtubules play a role in directing the radial arrangement of the cellulose micro-fibrils of guard cells. However, the role of microtubules in daily cycles of opening and closing of stomata is not clear. The organization of microtubules in guard cells of Commelina communis leaves was studied by analysis of three-dimensional immunofluorescent images. It was found that while guard cell microtubules in the epidermis of leaves incubated in the light were organized in parallel, straight and dense bundles, in the dark they were less straight and oriented randomly near the stomatal pore. The effect of blue and red light on the organization of guard cell microtubules resembled the effects of white light and dark respectively. When stomata were induced to open in the dark with fusicoccin, microtubules remained in the dark configuration. Furthermore, when incubated in the light, guard cell microtubules were more resistant to oryzalin. Similarly, microtubules of Arabidopsis guard cells, expressing green fluorescent protein-tubulin alpha 6, were disorganized in the dark, but were organized in parallel arrays in the presence of white light. The dynamics of microtubule rearrangement upon transfer of intact leaves from dark to light was followed in single stomata, showing that an arrangement of microtubules typical for light conditions was obtained after 1 h in the light. Our data suggest that microtubule organization in guard cells is responsive to light signals.     

Selective extraction of cotton fiber cytoplasts to identify cytoskeletal-associated proteins

Cytoplasts from cotton (Gossypium hirsutum L.) fiber cells retain microtubule and microfilament cytoskeletons through extraction with non-ionic detergent and ethylene glycol bis-(β-aminoethyl ether) N,N,N',N'-tetraacetic acid. Tubulin and actin are the most abundant proteins in extracted cytoplasts; however, many other less abundant proteins are also present. To determine if minor proteins were associated with the cytoskeleton, microtubules and microfilaments were selectively removed from extracted cytoplasts by detergent extraction in an alkaline Ca²⁺ solution. Under these extraction conditions, microtubules and microfilaments were fragmented and depolymerized unless previously stabilized by taxol and phalloidin. Associated proteins were identified by their loss in conjunction with either microtubules or microfilaments. As judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, one protein, of roughly 115 kDa, appeared to be associated with microfilaments since it was present in Ca²⁺-extracted preparations only when microfilaments were stabilized with phalloidin. The failure of most minor proteins to associate with microtubules and microfilaments suggests that caution must be used when interpreting co-isolation as evidence for an association of low abundance proteins with cytoskeletons.     

Characterization of the effects of metabolic inhibitors, ATPase inhibitors and a potassium-channel blocker on stomatal opening and closing in isolated epidermis of Commelina communis L.

Abstract. The specific effects of hypoxia and various inhibitors on stomatal opening in the light and closing in the dark were characterized in isolated epidermis from Commelina communis L. Reducing the guard cell metabolism with hypoxia and the uncoupler carbonyl cyanide-m-chloro-phenyl-hydrazone, CCCP, respectively, inhibited both stomatal opening and closing. Stomatal closing was very efficiently blocked by CCCP and this effect could be readily reversed by washing out the inhibitor. The authors were unable to inhibit stomatal opening with ATPase-inhibitors, without also affecting closing. Orthovanadate, up to 2 mol m⁻³, affected neither opening nor closing. Dicyclohexylcarbodiimide, DCCD, and diethylstilbestrol, DES, inhibited opening as well as closing to about 50%. The K⁺ -channel blocker tetraethylammonium chloride, TEA-Cl, inhibited both stomatal opening and closing, as did phenyl acetic acid, PAA, a compound considered to interfere with blue light induced stomatal opening. The results are discussed in the view that the uncontrolled K⁺ leakage from the guard cells is low, that K⁺ efflux during stomatal closing, as well as K⁺ influx during opening, occurs through specific K⁺-channels and that ATP and/or a membrane potential seems to be needed to keep these channels open.     

Nitric oxide,actin reorganization and vacuoles change are involved in PEG 6000‐induced stomatal closure in Vicia faba

Water deficit and the resulting osmotic stress affect stomatal movement. There are two types of signals, hydraulic and chemical signals, involving in the regulation of stomatal behavior responses to osmotic stress. Compared with the chemical signals, little has been known about the hydraulic signals and the corresponding signal transduction network and regulatory mechanisms. Here, using an epidermal‐strip bioassay and laser‐scanning confocal microscopy, we provide evidence that nitric oxide (NO) generation in Vicia faba guard cells can be induced by hydraulic signals. We used polyethylene glycol (PEG) 600 to simulate hypertonic conditions. This hydraulic signal led to stomatal closure and rapid promotion of NO production in guard cells. The effects were decreased by NO scavenger 2‐(4‐carboxyphenyl)‐4,4,5, 5‐tetramethylimidazoline‐1‐oxyl‐3‐oxide (c‐PTIO) and NO synthase (Enzyme Commission 1.14.13.39) inhibitor N^G‐nitro‐ l ‐Arg‐methyl ester (l ‐NAME). These results indicate that PEG 6000 induces stomatal closure by promoting NO production. Cytochalasin B (CB) inhibited stomatal closure induced by PEG 6000 but did not prevent the increase of endogenous NO levels, indicating that microfilaments polymerization participate in stomatal closure induced by PEG 6000, and may act downstream of NO signaling. In addition, big vacuoles split into many small vacuoles were observed in response to PEG 6000 and sodium nitroprusside (SNP) treatment, and CB inhibited these changes of vacuoles, the stomatal closure was also been inhibited. Collectively, these results suggest that the stomatal closure induced by PEG 6000 may be intimately associated with NO levels, reorganization of actin filaments and the changes of vacuoles, showing a crude outline of guard‐cells signaling process in response to hydraulic signals.     

The stomata of the fern Adiantum capillus-veneris do not respond to CO2 in the dark and open by photosynthesis in guard cells

The stomata of the fern Adiantum capillus-veneris lack a blue light-specific opening response but open in response to red light. We investigated this light response of Adiantum stomata and found that the light wavelength dependence of stomatal opening matched that of photosynthesis. The simultaneous application of red (2 micromol m(-2) s(-1)) and far-red (50 micromol m(-2) s(-1)) light synergistically induced stomatal opening, but application of only one of these wavelengths was ineffective. Adiantum stomata did not respond to CO2 in the dark; the stomata neither opened under a low intercellular CO2 concentration nor closed under high intercellular CO2 concentration. Stomata in Arabidopsis (Arabidopsis thaliana), which were used as a control, showed clear sensitivity to CO2. In Adiantum, stomatal conductance showed much higher light sensitivity when the light was applied to the lower leaf surface, where stomata exist, than when it was applied to the upper surface. This suggests that guard cells likely sensed the light required for stomatal opening. In the epidermal fragments, red light induced both stomatal opening and K+ accumulation in guard cells, and both of these responses were inhibited by a photosynthetic inhibitor, 3-(3,4-dichlorophenyl)-1,1-dimethylurea. The stomatal opening was completely inhibited by CsCl, a K+ channel blocker. In intact fern leaves, red light-induced stomatal opening was also suppressed by 3-(3,4-dichlorophenyl)-1,1-dimethylurea. These results indicate that Adiantum stomata lack sensitivity to CO2 in the dark and that stomatal opening is driven by photosynthetic electron transport in guard cell chloroplasts, probably via K+ uptake.     

Cytokinin- and auxin-induced stomatal opening is related to the change of nitric oxide levels in guard cells in broad bean

The relationship between cytokinin- and auxin-induced stomatal opening and nitric oxide (NO) levels in guard cells in broad bean was studied. Results indicate that cytokinins and auxins reduced the levels of NO in guard cells and induced stomatal opening in darkness. In addition, cytokinins not only reduced NO levels in guard cells caused by sodium nitroprusside (SNP) in light but also abolished NO that had been generated by dark, and then promoted the closed stomata reopening, as did NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide. However, unlike cytokinins, auxins not only had incapability to reduce NO levels by SNP but also could not abolish NO having been generated by dark, so auxins could not promote the closed stomata to reopen. The above-mentioned effects of auxins were similar to that of nitric oxide synthase (enzyme commission 1.14.13.39) inhibitor N ^G-nitro- l -Arg-methyl ester. Hence, it is concluded that cytokinins reduced probably the levels of NO in guard cells via scavenging, and auxins reduced NO levels through restraining NO generation in all probability, and then induced stomatal opening in darkness.