Effect of Hill Reaction Inhibitors on the Photoreduction of Ferricyanide and Cyclic Photophosphorylation by Spinach Chloroplasts

Some derivatives of phenylurea, N-phenylcarbamate, s-triazine and acylanilide inhibited the cyclic photophosphorylation of spinach chloroplasts catalyzed by phenazine methosulfate and accelerated the photosystem I-dependent electron flow estimated as the disproportionation of diphenylcarbazone. Acceleration was slightly stimulated by the simultaneous addition of methylamine. Thus, these Hill reaction inhibitors act as uncouplers of cyclic photophosphorylation as does methylamine. The inhibiting activities of the chemicals on the photoreduction of ferricyanide and on photophosphorylation had a parabolic relation to the partition coefficient in the octanol-water system of the chemicals.     

稀土积累对水体中藻类生长的影响

为了解稀土积累对水体中藻类生长的生态效应,本文研究了单一稀土氧化镧（Ｌａ２Ｏ３）积累对水体中混合藻生长量的影响。结果表明,稀土浓度为５０、１００、２００、３００、４００、６００、８００ｐｐｍ时,对混合藻的生长多表现为抑制作用。整个试验期间藻的叶绿素（ａ）含量及藻细胞数量均随着稀土浓度的升高而降低。只是稀土浓度为１００ｐｐｍ,培养１５天时对藻产生轻微刺激作用。当稀土浓度＞４００ｐｐｍ时,混合藻的生长几乎完全被抑制。     

Some Factors Affecting the Hill Reaction Activity in Cotton Chloroplasts

A method of plant culture was developed for growing large leaves of glandless cotton on single stems. Chloroplasts isolated from these leaves actively reduced ferricyanide when assayed for the Hill reaction. Hill reaction activity increased 133% when the 0.5 m sucrose isolation medium was replaced with 10% (w/v) polyethylene glycol, both buffered at pH 7.6. The presence of 2 or 5% (w/v) bovine serum albumin in the sucrose buffer did not increase Hill activity. Ferricyanide reduction in the dark occurred in all assays, and the possibility of gossypol as the reductant is discussed. Half-life of the chloroplasts stored in 10% glycerol at -23 C was 23 days. The ammonium ion at 0.01 m enhanced Hill reaction activity up to 171%. Leaves containing chloroplasts with the highest Hill reaction activity were found near the 8th node below the apex. Leaf water potentials less than -28 bars reduced the activity about 50%. Daylight conditions during the winter months in the greenhouse reduced the activity about 30%.     

钾营养对水稻光合速率（Pn）、Hill反应及SOD活力日变化的影响

晴天,田间水稻顶部完全展开叶最大的Ｐｎ出现在上午８时半左右。低钾营养加剧了“午睡”。８：３０～１４：３０高光强期间Ｐｎ与气孔导度和Ｃｉ分别呈显著直线正相关。Ｈｉｌｌ反应活力午后最低,但该时低钾水稻的Ｈｉｌｌ反应活力较钾充足水稻高。ＳＯＤ活力早晨最低,中午该酶活力增加程度在低钾水稻中更为明显。上述各项均存在着品种间的差异。因此,低钾下水稻“午睡”的加剧由低气孔导度所致,较长时间的低Ｃｉ会诱发低的Ｈｉｌｌ反应活力。     

The Effect of Irradiance on Hill Reaction Activity of Atrazine-resistant and -susceptible Biotypes of Weeds

Significantly lower Hill reaction activity together with greater sensitivity to photoinhibitory conditions was observed at various irradiances in atrazine-resistant biotypes ofSenecio vulgaris L., Amaranthus retroflexus L., and Poa annua L. compared to the susceptible ones.     

软体动物粗蛋白对藻类的凝集作用

采用绿色巴夫藻（Pavlova viridis)、盐藻（Dunaliella salina)、塔胞藻（Pyramimonas sp.)、海产小球藻（Chlorella vulgaris)、亚心型扁藻（Pyatymonas cordiformis)、蛋白核小球藻（Chlorella pyrenoidosa)、紫球藻（Porphyridium purpureum)等7种单细胞藻类对福建省10种常见软体动物粗蛋白提取物进行凝集活性筛选,其中有7种动物粗蛋白显示出对藻类细胞有凝集活性。同时,发现紫球藻的敏感性强于其他种类。这些粗蛋白的凝集活性在不同酸碱度和高温下表现出较强的稳定性,尤其是薄壳绿螂、菲律宾蛤仔、斑玉螺、短蛸的粗蛋白在95℃恒温15min后仍有活性。这些动物粗蛋白对紫球藻的凝集活性可以被0.02mol/L和0.04mol/L的EDTA所抑制,同时还能为9种糖类所抑制。     

Effect of Bentazon, a Hill Reaction Inhibitor, on Symbiotic Nitrogen-fixing Capability and Apparent Photosynthesis

Symbiotic associations of bean plants (Phaseolus vulgaris L. cv. Blue Lake) and Rhizobium phaseoli strain 127K17 were treated with the Hill reaction inhibitor bentazon (3-isopropyl-1 H-2,1,3-benzothiadiazin-4-(3H)-one-2,2-dioxide). Plants receiving foliar and root treatments of 1.8 kilograms per hectare bentazon were assayed at 6 hour intervals for N₂-fixing capacity by measuring C₂H₂-dependent C₂H₄ production and H₂ evolution and for CO₂ exchange rates. In foliar treated plants greatest measured inhibition of CO₂ exchange rates and N₂-fixing capacity occurred 6 and 12 hours after treatment, respectively. In root-treated plants maximum inhibition of both processes was delayed by 6 hours, and was less severe than in foliar treated plants. Nitrogen-fixing capacity and CO₂ exchange rate recovered to control levels in all plants. Application of higher rates of bentazon resulted in greater inhibition of CO₂ exchange rate and N₂-fixing capacity. Inhibition of the two processes was positively correlated (r = 0.985). The results indicate that inhibition of N₂-fixing capacity was not caused by bentazon directly, but indirectly through limiting the availability of photosynthate to support root nodule activity.     

溶液介电常数对铜锌超氧化物歧化酶活性的影响

溶液介电常数对天然酶和修饰酶的活性影响不同,天然酶随介电常数增加而酶活性下降,修饰酶则反之,这表明静电相互作用在铜锌超氧化物歧化酶(Cu·Zn-SOD)与超氧阴离子(-O_2~(·-))反应过程中起着重要作用,酶分子活性中心附近ε-NH_3~+为O_2~(·-)进入活性中心提供静电吸引力。在有机溶剂中,SOD的构象会发生变化,从而导致酶活性降低。实验还表明,Cl~-对SOD有明显的抑制作用。     

气孔保卫细胞信号转导中的第二信使

介绍了保卫细胞信号转导中第二信使的种类、特征、调控机制以及第二信使之间的相互作用,特别是钙信使和质子信使之间的相互关系。     

Studies on the Free Radical in Amino-Carbonyl Reaction

A relatively stable free radical signal was detected by ESR spectroscopy in the mela-noidin prepared from glycine and glucose. All attempts made to remove molecular oxygen from the melanoidin matrix resulted in a reversible increase in signal height without changing the line width and g-value of central resonance. Nitric oxide, a well-known quenching agent for radicals, retarded the reaction ensuing in disappearance of furfurals and deposition of a new compound. These results allowed to envisage a steps of free radical formation involved in the amino-carbonyl reaction and also nature of the free radical species.     

赤潮藻毒素生物合成研究进展

合成毒素是赤潮藻类的一个常见特征,已知能够产生毒素的微藻有70多种。作为次级代谢产物,藻毒素的产生可能是一种压制或清除其它藻类竞争者的一种反应,在群落演替、种间竞争中发挥重要作用。目前,人们对藻毒素生物合成机理依然知之甚少,相关基因的研究仍无明显突破。利用环境因子诱导毒素生成变化进而分离差异表达基因或者比较不同产毒藻株间基因表达的差异,从中克隆藻毒素生物合成基因似乎是一种极具潜力的研究方向。     

Studies of the Effect of Tenuazonic Acid on Plant Cells and Seedlings

The biological and biochemical studies of the effect of tenuazonic acid on plant cells and seedlings were carried out. Tenuazonic acid exhibited a conspicuous stunting effect on the seedling-growth of rice plant, mung bean, radish and turnip, and on the growth of suspension cultured cells of soybean and rice plants. Tenuazonic acid exhibited no effect on the O₂-uptake and the activity of SH-enzyme of the plant, but inhibited the incorporation of ¹⁴C-Ieucine into the protein fraction and that of ¹⁴C-adenine into nucleic acid fraction of suspension cultured soybean cells as well as these uptake into the cells. And then it has been proved that these incorporation-inhibitions were not merely due to the inhibition of ¹⁴C-leucine and ¹⁴C-adenine uptake into the cells but based on the intrinsic inhibition of protein and nucleic acid syntheses, respectively.     

Digestion of Algal Biomass for Electricity Generation in Microbial Fuel Cells

We developed a semi-automated genome analysis system called GAMBLER in order to support the current whole-genome sequencing project focusing on alkaliphilic Bacillus halodurans C-125. GAMBLER was designed to reduce the human intervention required and to reduce the complications in annotating thousands of ORFs in the microbial genome. GAMBLER automates three major routines: analyzing assembly results provided by genome assembler software, assigning ORFs, and homology searching. GAMBLER is equipped with an interface for convenience of annotation. All processes and options are manipulatable through a WWW browser that enables scientists to share their genome analysis results without choosing computer platforms.     

Effect of pH on Inorganic Carbon Uptake in Algal Cultures

Biomass production by the green algae Scenedesmus obliquus and Chlorella vulgaris in intensive laboratory continuous cultures was considerably affected by the pH at which the cultures were maintained. Carbon photoassimilation experiments revealed that pH values in the range of 8 to 9 were important for determining the free CO₂ concentrations in the medium. With higher pH values, additional pH effects were observed involving a decrease in the relative high affinity of low CO₂-adapted algae to free CO₂. The carbon uptake rate by high CO₂-adapted algae after transfer to low free CO₂ medium was characterized by a lag period of about 30 min, after which the affinity of the algae to CO₂ increased considerably. Both continuous growth and carbon uptake experiments indicated that artificially maintained high free CO₂ concentrations are recommended for maximal production in intensive outdoor algal cultures.     

Further Studies on the Effect of 5-Iododeoxyuridine on Polyoma Virus Multiplication in Mouse Cells

5-Iododeoxyuridine (IUDR) inhibited production of infectious polyoma virus in mouse embryo cells and mouse kidney cells in culture. Deoxythymidine reversed its effect. IUDR did not inactivate infectivity of free virus particles. IUDR did not prevent adsorption and penetration of polyoma virus to cells. The events sensitive to IUDR treatment occurred at around 20 hours after infection. The cytopathic effects of polyoma virus, including emergence of DNA containing-inclusions in the nucleus, were observable in infected cells in which viral replication was completely arrested by IUDR. It was shown by fluorescent antibody technique in infected mouse embryo cells and by complement fixation test in infected mouse kidney cells that IUDR inhibited completely the synthesis of viral antigen. No virus-like particles were demonstrated in the IUDR-treated infected-mouse kidney cells by electron microscope examinations.