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1.
The extract of the luminous mushroom Panellus stipticus wasonly slightly chemiluminescent but, when treated with methylamine,it developed a strong capability of chemiluminescence whichcorresponds to the total light emission in 45 h fromthe fresh, brightly luminescing specimens before extraction.The chemiluminescent compounds thus formed, as well as the precursorcompounds that yielded the chemiluminescent compounds, werepurified and their properties were investigated. The purifiedchemiluminescent compounds (3 kinds) were orange coloured solids(absorption maxima 210 nm and 488 nm) and showed yellowish fluorescence(emission maximum 520530 nm) when dissolved in variousorganic solvents or in aqueous buffer solutions containing asurfactant. The precursor compounds (2 kinds) were colourlessoils (absorption maximum 215 nm) and non-fluorescent. The chemiluminescencereaction in aqueous pH 8?0 buffer solutions required the presenceof , O2, and a surfactant. The spectral distributionand intensity of chemiluminescence was significantly affectedby the type of surfactant used, resulting in emission peaksof various intensities in a broad wavelength range of 480 nmto 530 nm. Various lines of evidence suggest that the chemiluminescencereaction studied might be closely related with the bioluminescencereaction of P. stipticus (emission maximum 530 nm). Key words: Superoxide anion, chemiluminescence, bioluminescence, luminous fungi 相似文献
2.
Active oxygen participation in chlorophyll destruction and lipid peroxidation in SO2-fumigated leaves of spinach 总被引:1,自引:0,他引:1
Shimazaki Ken-ichiro; Sakaki Takeshi; Kondo Noriaki; Sugahara Kiyoshi 《Plant & cell physiology》1980,21(8):1193-1204
Chlorophyll a and carotenoids of spinach began to be destroyed2 to 3 hr after fumigation with 2 ppm SO2 under light, whereaschlorophyll b was undamaged during 8 hr of exposure to SO2.Pheophytin a was not affected by the fumigation. When disks excised from leaves fumigated with SO2 at 2 ppm for2 hr were illuminated, chlorophyll a and carotenoids were brokendown, while they were not destroyed in darkness. The destructionof these pigments was suppressed under nitrogen. Chlorophylla destruction was inhibited by l,2-dihydroxybenzene-3,5-disulfonate(tiron), hydro-quinone and ascorbate, but not by l,4-diazabicyclo-[2,2,2]-octane(DABCO), methio-nine, histidine, benzoate and formate. Chlorophylla destruction was inhibited by phenazine methosulfate but stimulatedby methyl viologen. Addition of superoxide dismutase (SOD) tothe homogenate of SO2-fumigated leaves inhibited the chlorophylla destruction. The activity of endogenous SOD was reduced to40% by 2-hr fumigation before the loss of chlorophyll was observed.These results suggest that chlorophyll a destruction by SO2was due to superoxide radicals (O2). Moreover, malondialdehyde (MDA), a product of lipid peroxidation,was formed in SO2-fumigated leaves. MDA formation was inhibitedby tiron, hydroquinone and DABCO but not by benzoate and formate.MDA formation was increased by D2O. These results suggest thatlipid peroxidation in SO2-fumigated leaves was due to singletoxygen 1O2 produced from O2. (Received May 15, 1980; ) 相似文献
3.
Active oxygen participation in chlorophyll destruction and lipid peroxidation in SO2-fumigated leaves of spinach 总被引:22,自引:0,他引:22
Shimazaki Ken-ichiro; Sakaki Takeshi; Kondo Noriaki; Sugahara Kiyoshi 《Plant & cell physiology》1980,21(7):1193-1204
Chlorophyll a and carotenoids of spinach began to be destroyed2 to 3 hr after fumigation with 2 ppm SO2 under light, whereaschlorophyll b was undamaged during 8 hr of exposure to SO2.Pheophytin a was not affected by the fumigation. When disks excised from leaves fumigated with SO2 at 2 ppm for2 hr were illuminated, chlorophyll a and carotenoids were brokendown, while they were not destroyed in darkness. The destructionof these pigments was suppressed under nitrogen. Chlorophylla destruction was inhibited by l,2-dihydroxybenzene-3,5-disulfonate(tiron), hydro-quinone and ascorbate, but not by l,4-diazabicyclo-[2,2,2]-octane(DABCO), methio-nine, histidine, benzoate and formate. Chlorophylla destruction was inhibited by phenazine methosulfate but stimulatedby methyl viologen. Addition of superoxide dismutase (SOD) tothe homogenate of SO2-fumigated leaves inhibited the chlorophylla destruction. The activity of endogenous SOD was reduced to40% by 2-hr fumigation before the loss of chlorophyll was observed.These results suggest that chlorophyll a destruction by SO2was due to superoxide radicals (O2). Moreover, malondialdehyde (MDA), a product of lipid peroxidation,was formed in SO2-fumigated leaves. MDA formation was inhibitedby tiron, hydroquinone and DABCO but not by benzoate and formate.MDA formation was increased by D2O. These results suggest thatlipid peroxidation in SO2-fumigated leaves was due to singletoxygen 1O2 produced from O2. (Received May 15, 1980; ) 相似文献
4.
The chemical structure of two luciferin precursors PS-A and PS-B, isolated from the luminous mushroom Panellus stipticus, were determined as 1-O-decanoylpanal (2) and 1-O-dodecanoylpanal (3), respectively. Both PS-A and PS-B were converted into chemiluminescent luciferins by treatment with 50 mmol/l methylamine in a pH 3.5 buffer solution containing an anionic surfactant Tergitol 4 at 25–35ºC. The luciferins emitted chemiluminescence in a pH 7–8 buffer solution containing a cationic surfactant in the presence of O2 and O. 相似文献
5.
Electron spin resonance (ESR) spectroscopy has provided evidencefor involvement of the superoxide anion (O2) radicalin the conversion of l-aminocyclopropane-l carboxylic acid (ACC)to ethylene by microsomal membranes from etiolated pea seedlings.Formation of ethylene from ACC by the membrane system is oxygen-dependent,heat denaturable, inhibited by the radical scavenger n-propylgallate and sensitive to superoxide dismutase (SOD) and catalase.Addition of 1,2-dihydroxybenzene-3,5-disulfonic acid (Tiron)to the reaction mixture results in formation of the Tiron semiquinone(Tiron radical) ESR signal derived from O2, and alsoinhibits ethylene production. The radical signal is oxygen-dependentand inhibited by SOD and catalase, but is formed both in thepresence and absence of ACC. Heat denaturation of the microsomalenzyme system completely blocks formation of the radical signal.The data collectively suggest that O2 generated by amembrane-bound enzyme facilitates the conversion of ACC to ethylene. (Received September 8, 1981; Accepted January 19, 1982) 相似文献
6.
该文比较研究了黑暗和光照条件下C3盐生植物盐地碱蓬(Suaeda salsa)叶片甜菜红素积累和H2O2含量及其抗氧化酶活性的关系,实验分析了甜菜红素体外抗氧化性能,以期揭示诱导盐地碱蓬甜菜红素积累的可能机制以及甜菜红素积累的生理生态意义。结果表明:暗期处理和营养液中加入一定浓度的H2O2都明显促进盐地碱蓬叶片H2O2含量、甜菜红素的含量、超氧化物歧化酶(SOD)和过氧化氢酶(CAT)的活性,而且叶片中 H2O2含量与甜菜红含量、SOD和CAT活性具有正相关性;盐地碱蓬甜菜红素体外清除羟自由基的能力明显强于维生素C,而清除超氧阴离子能力低于维生素C。这些结果表明:黑暗作为一种环境胁迫因子诱导盐地碱蓬叶片甜菜红素的积累可能是由自由基介导的,甜菜红素的积累可能与提高植物的抗氧化能力有关。 相似文献
7.
Generation of superoxide anion radicals by the marine phytoplankton organism, Chattonella antiqua 总被引:1,自引:0,他引:1
The generation of superoxide anion radical (O2, believedto be a causative factor in the killing of fish by the phytoplanktonChattonella antiqua, has been examined using several methods:electrochemical technique, reduction of ferricytochrome c andfluorescent laser microscope. Evidence is presented to suggestthat these organisms release superoxide continuously while theyare living, even in the resting state. Additional generationof O2 accompanies the discharge of mucocysts, and istriggered when they are exposed to mucus from the gill lamellaeof fish. Such instantaneous generation of O2 is alsoinduced when the organisms are in contact with an electrodepoised at a potential of +0.1 V versus Ag/AgCI, which is positiveenough to oxidize O2 to O2. 相似文献
8.
Ogawa Ken'ichi; Kanematsu Sumio; Takabe Keiji; Asada Kozi 《Plant & cell physiology》1995,36(4):565-573
In chloroplasts O2 is photoproduced via the univalentreduction of O2 in PSI even under conditions that are favorablefor photosynthesis. The photogenerated O2 is disproportionatedto H2O2 and O2 in a reaction that is catalyzed by superoxidedismutase (SOD). The H2O2-scavenging ascorbate peroxidase isbound to the thylakoid membranes at or near the PSI reactioncenter [Miyake and Asada (1992) Plant Cell Physiol. 33: 541],and the primary product of oxidation in the peroxidase-catalyzedreaction, the monodehydroascorbate radical, is photoreducedto ascorbate in PSI in a reaction mediated by ferredoxin [Miyakeand Asada (1994) Plant Cell Physiol. 35: 539]. Therefore, SODshould be localized at or near the PSI complex. We report herethe microcompartmentalization of the chloroplastic CuZn-SODon the stromal-faces of thylakoid membranes where the PSI-complexis located. Spinach leaves were fixed and substituted by a rapidfreezing and substitution method that allows visualization ofintact chloroplasts. The embedded sections were immuno labeledwith the antibody against CuZn-SOD by the immunogold method.About 70% of the immunogold particles were found within 5 nmfrom the surface of the stromal-faces of thylakoid membranes.Of these particles, about 40% were found at the ends and marginsof the grana thylakoids and 60% were found on the stromal sideof the stromal thylakoids. From these results, the local concentrationof CuZn-SOD on the stroma-facing surfaces of the thylakoid membraneswas estimated to be about 1 mM. The effect of the microcompartmentalizationof CuZn-SOD on the scavenging of superoxide radicals is discussed. (Received November 25, 1994; Accepted February 23, 1995) 相似文献
9.
Selective inhibition of antimycin A-insensitive respiration in Ustilago maydis and Ceratocystis ulmi
Sporidia of Ustilago maydis and conidia of Ceratocystis ulmipossess an antimycin A and azide-tolerant electron transportpathway which apparently diverts electrons to O2 from some pointon the substrate side of the antimycin A block. The alternatepathway (induced by 0.5 µg/ml antimycin A or 5x104M sodium azide) supports a respiratory rate 1.52 timesthat of the normal system, but has a terminal oxidase with alower than normal affinity for O2. A similarly high respiratoryrate in U. maydis is supported by the normal pathway when uncoupledby 4 µg/ml of 4,5-dichloro-2-trifluoromethylbenzimidazole,but a high affinity for O2 in this case indicates that the normalterminal oxidase is utilized. Respiration by the normal pathway in both fungi is only slightlyor moderately inhibited by 1.5x103 M benzohydroxamicacid (BHAM) and 5x104 M 8-hydroxyquinoline. The alternatepathway in U. maydis, however, is inhibited as much as 84 and92% respectively by these two compounds, while alternate respirationin C. ulmi can be inhibited as much as 86 and 76% respectively.BHAM, 8-hydroxyquinoline, 2-pyridinethiol-1-oxide, a,a'-dipyridyl,carboxin, and diphenylamine inhibit alternate respiration ata site on the alternate pathway which is not part of the normalelectron transport system. Antimycin A and azide-insensitiverespiration found in U. maydis and C. ulmi closely resemblesinhibitor insensitivity noted in several fungi and some higherplants. Such an alternate respiratory pathway may be an earlystep in the evolution of oxidative phosphorylation. (Received June 27, 1972; ) 相似文献
10.
Kim Daekyung; Nakashima Takuji; Matsuyama Yukihiko; Niwano Yoshimi; Yamaguchi Kenichi; Oda Tatsuya 《Journal of plankton research》2007,29(3):241-247
Raphidophycean flagellates, Chattonella marina and C. ovata,are harmful red tide phytoplankters; blooms of these phytoplanktersoften cause severe damage to fish farming. Previous studieshave demonstrated that C. marina and C. ovata continuously producereactive oxygen species (ROS) such as superoxide anion (O2)hydrogen peroxide (H2O2) under normal growth conditions, andan ROS-mediated toxic mechanism against fish and other marineorganisms has been proposed. Although the exact mechanism ofROS generation in these phytoplankters still remains to be clarified,our previous study suggested that NADPH oxidase-like enzymelocated on the cell surface of C. marina may be involved inO2 generation. To investigate the localization of O2and H2O2 generation in C. marina and C. ovata, we employed 2-methyl-6(p-methoxyphenyl)-3,7-dihydroimidazo[1,2-a]pyrazin-3-oneand 5-(and-6)-carboxy-2',7'-dichlorodihydrodihydrofluoresceindictate, acetyl ester, which are specific fluorescent probefor detecting O2 and H2O2, respectively. Observationby fluorescence microscopy of live phytoplankters incubatedwith each probe revealed that O2 is mainly generatedon the cell surface, whereas H2O2 is generated in the intracellularcompartment in these phytoplankters. When the cells were rupturedby ultrasonic treatment, O2 levels of C. marina and C.ovata decreased significantly, whereas a few times higher levelsof H2O2 were detected in the ruptured cell suspensions whencompared with the levels of the live cell suspension. In immunoblottinganalysis, the protein recognized by anti-human gp91 phox wasdetected in both species. These results suggest that, in bothphytoplankters, the underlying mechanisms of O2 and H2O2generation may be distinct and such systems are independentlyoperating in the cells. 相似文献
11.
Scavenging of Hydrogen Peroxide in Prokaryotic and Eukaryotic Algae: Acquisition of Ascorbate Peroxidase during the Evolution of Cyanobacteria 总被引:4,自引:0,他引:4
Ascorbate (AsA) peroxidase was found in six species of cyanobacteriaamong ten species tested. Upon the addition of H218O2 to thecells of AsA peroxidase-containing cyanobacteria, 16O2 derivedfrom water and 18O2 derived from H2I8O2 were evolved in thelight. The evolution of 16O2 was inhibited by DCMU and did notoccur in the dark, but I8O2 was evolved even in the dark orin the presence of DCMU. Similar light-dependent evolution of16O2 was observed in the cells of AsA peroxidase-containingEuglena and Chlamydomonas. However, the cells of AsA perox-idase-lackingcyanobacteria evolved only 18O2 in either the light or dark.Furthermore, the quenching of chlorophyll fluorescence inducedby hydrogen peroxide was observed only in the cells of the AsAperoxidase-containing Synechocystis 6803, and not in the cellsof Anacystis nidulans which lacks AsA peroxidase. Thus, cyanobacteriacan be divided into two groups, those that has and those thatlacks AsA peroxidase. The first group scavenges hydrogen peroxidewith the peroxidase using a photoreductant as the electron donor,and the second group only scavenges hydrogen peroxide with catalase. (Received July 23, 1990; Accepted October 18, 1990) 相似文献
12.
Drought Tolerance in Two Mosses: Correlated with Enzymatic Defence Against Lipid Peroxidation 总被引:55,自引:2,他引:53
Drought-induced changes in the activities of superoxide dismutase(SOD) and catalase, level of lipid peroxidation, and membranepermeability (solute leakage) have been studied in two mosses,the drought-tolerant Tortula ruralis and the drought-sensitiveCratoneuron filicinum. In T. ruralis the activities of SOD andcatalase increase during slow drying. The level of lipid peroxidationconsequently declines. On subsequent rehydration the enzymeactivities decline and the level of lipid peroxidation risesgradually to normal levels. The leakage of preloaded 86Rb onrehydration of slowly dried T. ruralis is similar to that inturgid moss, i.e. leakage of about 20% of tissue 86Rb. WhenT. ruralis is subjected to rapid drying there is no change inthe enzyme activities or in lipid peroxidation. However, whenthis moss is rehydrated there is a large immediate increasein lipid peroxidation. Half of the tissue 86Rb is leaked intothe bathing medium during the first hour of rehydration. Butwithin the next hour, when SOD and catalase activities haveincreased to high levels, lipid peroxidation quickly declinesto a level lower than that in the turgid control moss, and the86Rb leaked earlier is partly reabsorbed indicating that membranerepair is well underway. On prolonged rehydration the enzymeactivities decline and the level of lipid peroxidation risesgradually to reach normal levels found in control turgid moss.In the case of drought-sensitive C. filicinum the activitiesof SOD and catalase decline during drying as well as duringsubsequent rehydration. There is a rapid increase in lipid peroxidationduring rehydration and most of the preloaded 86Rb leaks intothe bathing medium irreversibly. The changes in lipid peroxidationduring drying and subsequent rehydration of both the mossesappear to coincide in time with the reported changes in O2 uptake,indicating that the drought-induced membrane damage may be dueto free radical-induced lipid peroxidation which is known torequire active O2 uptake. Furthermore, there appears to be agood correlation between an ability of the tissue to controllipid peroxidation and its ability to retain solutes. It issuggested that ability of plant tissues to mobilize enzymaticdefence against uncontrolled lipid peroxidation may be an importantfacet of their drought tolerance. 相似文献
13.
GRODZINSKI BERNARD; JAHNKE SIEGFRIED; THOMPSON ROBERT 《Journal of experimental botany》1984,35(5):678-690
Tracer amounts of atmospheric [13N]-Iabelled ammonia gas, wereabsorbed by leaves of Lupinus albus and Helianthus annuus inboth the light and the dark. Exogenous [13N]-ammonia was onlyabsorbed in the dark when the feeding occurred shortly aftera period of illumination and the tissue was not depleted ofits carbohydrate reserves (e.g. starch). Incorporation of the[13N]-ammonia appeared to occur via the leaf glutamine synthetase/glutamatesynthase (GS/GOGAT) cycle since 2.0 mol m3 MSX, an inhibitorof the GS reduced uptake in both the light and dark. Photosyntheticincorporation of 11CO2 was not affected by this treatment Therate of movement of [13N]-assimilates in the petiole of attachedleaves of Helianthus and Lupinus was similar to that of the11Cl-photo assimilates. Export of both [13N] and [11C]-Iabelledassimilates from the leaf and movement in the petiole in boththe light and the dark was inhibited by source leaf anoxia (i.e.nitrogen gas). Translocation was re-established at the samerate when the feed leaf was exposed to gas containing more than2% O2 which permitted dark respiration to proceed. After aninitial feeding of either 11CO2 or [13N]-ammonia at ambient(21%) O2 exposure of the source leaf to 2% O2, or 50% O2 didnot alter the rates of translocation, indicating that changesin photosynthetic activity in the source leaf due to photorespiratoryactivity need not markedly alter, at least during the shortperiod, the loading and translocation of either [11C ] or [13N]-labelledleaf products. Key words: Translocation, CO2, NH3, Leaves, Helianthus annuus, Lupinus albus 相似文献
14.
Gametophytic self-incompatibility, a mechanism that preventsinbreeding in some families of flowering plants, is mediatedby the products of a single genetic locus, the S-locus. Theproducts of the S-gene in the female sexual tissues of Nicotianaalata are an allelic series of glycoproteins with RNase activity.In this study, we report on the microheterogeneity of N-linkedglycosylation at the four potential N-glycosylation sites ofthe S2-glycoprotein. The S-glycoproteins from N.alata containfrom one to five potential N-glycosylation sites based on theconsensus sequence Asn-Xaa-Ser/Thr. The S2-glycoprotein containsfour potential N-glycosylation sites at Asn27, Asn37, Asn138and Asn150, designated sites I, n, IV and V, respectively. SiteIII is absent from the S2-glycoprotein. Analysis of glycopeptidesgenerated from the S2-glycoprotein by trypsin and chymotrypsindigestions revealed the types of glycans and the degree of microheterogeneitypresent at each site. Sites I (Asn27) and IV (Asn138) displaymicroheterogeneity, site II (Asn37) contains only a single typeof N-glycan, and site V (Asn150) is not glycosylated. The microheterogeneityobserved at site I on the S2-glycoprotein is the same as thatobserved at the only site, site I, on the Srglycoprotein (Woodwardet al., Glycobiology, 2, 241-250, 1992). Since the N-glycosylationconsensus sequence at site I is conserved in all S-glycoproteinsfrom other species of self-incompatible solanaceous plants,glycosylation at this site may be important to their function.No other post-translational modifications (e.g. O-glycosylation,phosphorylation) were detected on the S2-glycoprotein. fertilization microheterogeneity N-glycans plants RNase 相似文献
15.
In "air-grown" Chroomonas sp. cells, low concentrations of DCMU(less than 0.1 µM) could prevent the inhibition of 14CO2fixation by anaerobiosis under light-saturating conditions (morethan 40 W.m2), with phenazine methosulfate showing asimilar effect. Antimycin A, carbonyl cyanide m-chlorophenylhydrazone(CCCP), and N,N'-dicyclohexylcarbodiimide strongly inhibitedanaerobic photosynthesis at concentrations which did not significantlyinhibit the rate under 2% O2 at high light intensity (200 W.m2),although 0.2 µM CCCP stimulated the rate under 2% O2 tosome extent. On the other hand, KCN inhibited the rate muchmore strongly under 2% O2 than N2, although it inhibited therate very strongly at concentrations above 5 µM both underN2 and 2% O2. These results suggest that the inhibition of photosynthetic14CO2 fixation by anaerobiosis in this alga result from ATPdeficiency caused by over-reduction of electron carriers ofthe cyclic electron flow and that oxygen can prevent the over-reduction.Cyclic electron flow seems to be necessary to provide additionalATP for CO2 reduction under anaerobic conditions, although itseems to be less necessary under aerobic conditions. (Received July 21, 1983; Accepted January 23, 1984) 相似文献
16.
Possible physiological mechanisms for production of hydrogen peroxide by the ichthyotoxic flagellate Heterosigma akashiwo 总被引:2,自引:0,他引:2
Blooms of the toxic red tide phytoplankton Heterosigma akashiwo(Raphidophyceae) are responsible for substantial losses withinthe aquaculture industry. The toxicological mechanisms of H.akashiwoblooms are complex and to date, heavily debated. One putativetype of ichthyotoxin includes the production of reactive oxygenspecies (ROS) that could alter gill structure and function,resulting in asphyxiation. In this study, we investigated thepotential of H.akashiwo to produce extracellular hydrogen peroxide,and have investigated which cellular processes are responsiblefor this production. Within all experiments, H.akashiwo producedsubstantial amounts of hydrogen peroxide (up to 7.6 pmol min1104 cells1), resulting in extracellular concentrationsof ~0.5 µmol l1 H2O2. Measured rates of hydrogenperoxide production were directly proportional to cell density,but at higher cell densities, accuracy of H2O2 detection wasreduced. Whereas light intensity did not alter H2O2 production,rates of production were stimulated when temperature was elevated.Hydrogen peroxide production was not only dependent on growthphase, but also was regulated by the availability of iron inthe medium. Reduction of total iron to 1 nmol l1 enhancedthe production of H2O2 relative to iron replete conditions (10µmol l1 iron). From this, we collectively concludethat production of extracellular H2O2 by H.akashiwo occurs througha metabolic pathway that is not directly linked to photosynthesis. 相似文献
17.
Reactions of birch leaves to changes in light during early ontogeny: comparison between in vivo and in vitro techniques to measure carbon uptake 总被引:1,自引:0,他引:1
Trends in several photosynthetic parameters and their responseto changed growth light were followed for 15 d in leaves ofyoung birch saplings using a rapid-response gas exchange measuringequipment. These in vivo measurements were compared to biochemicalassays that were made from the same leaves after the gas exchangestudies. The measurements were made on leaves that were selectedprior to the study and were at that time of similar age. Forthe first 7 d the photosynthetic parameters were followed fromthe growth conditions of moderate light (200 µmol m2s1; referred to as controls later in the text). On day7 some of the saplings were transferred to grow either underhigh (450 µmol m2 s1; referred to as highlight plants) or low (75 µmol m2 s1; referredto as low light plants) light and the capability of the preselectedleaves for acclimation was followed for 6 d. For comparison,at the end of the experiment the measurements were made on bothcontrols and on young leaves that had developed under high andlow light. Generally the in vivo measured rate of CO2 uptake (gross photosynthesis)both at 310 ppm CO2 and 2000 ppm CO2 corresponded very wellto the biochemically determined CO2 fixation capacity in vitroafter rapid extraction (measured as the initial and total activityof Rubisco, respectively). However, if the flux of CO2 intothe chloroplasts was limited by the closure of the stomata,as was the case of the high light plants, then the in vitromeasured Rubisco activity was greater than the in vivo measuredCO2 uptake. Vmax, calculated from the mesophyll conductanceat 1% O2, exceeded the initial activity of Rubisco (assayedat saturating RuBP and CO2) constantly by 60%. The catalyticactivity of Rubisco in birch leaves was overall very low, evenwhen calculated from the total activity of Rubisco (Kcat 0.631.18 s1), when compared to herbaceous C3 species. Signs of light acclimation were not observed in most of thephotosynthetic parameters and in chloroplast structure whenmature birch leaves were subjected to changes in growth lightfor 6 d. However, the change of the growth light either to highor low light caused day-to-day fluctuations in most of the measuredphotosynthetic parameters and in the case of the high lightplants signs of photoinhibition and photodestruction were alsoobserved (decrease in the amount of chlorophyll and increasein chlorophyll a/b ratio). As a result of these fluctuationsthese plants achieved a new and lower steady-state conditionbetween the light and dark reactions, as judged from the molarratio of RuBP to Rubisco binding site. Key words: Acclimation, photosynthesis, light, Rubisco, birch 相似文献
18.
Effects of Preillumination on Dark Nitrogen Fixation and Respiration by Anabaena Cylindrica 总被引:1,自引:0,他引:1
In whole filaments of Anabaena cylindrica dark nitrogen-fixingactivity (measured as acetylene reduction) and respiration increasedwith the light intensity of a fixed period of preillumination,saturating at ca. 10,000 lux. With saturating light during preillumination,the amount and duration of dark nitrogen-fixing activity increasedwith length of preillumination, but respiration declined rapidlyin the dark. At dark respiration rates below 250 nmol O2 uptake mg protein1?h1(State 1) no significant nitrogen-fixing activity is observed.From 250 to 550 nmol O2 uptake?mg protein1?h1(State 2), nitrogen-fixing activity depends on O2 uptake whileabove 550 nmol O2 uptake?mg protein1?h1 (State3), nitrogen-fixing activity no longer increases with furtherincrease in O2 uptake rate. (Received June 18, 1983; Accepted November 10, 1983) 相似文献
19.
Kenichi Mori Satoshi Kojima Shojiro Maki Takashi Hirano Haruki Niwa 《Luminescence》2011,26(6):604-610
Bioluminescent fungi are widely distributed on land and most belong to the class Basidomycetes. Light of about 530 nm wavelength maximum is emitted continuously. The molecular basis for the light‐emitting process remains unclear. We investigated the characteristics of the bioluminescence using cultivated fruiting bodies of M. chlorophos. Only fresh fruiting bodies exhibited long‐lasting light emission; rapid decay of light emission was observed with frozen and freeze‐dried samples. Freeze‐dried samples can be stored at room temperature under dry conditions and may be useful for the isolation of luciferin. The light emission of the fresh fruiting bodies was maintained in various buffers at varying pH; it could be stopped with pH 4 acetate buffer and could be recovered at pH 6. The isolation of luciferin from the fresh fruiting bodies might be possible by the control of buffer pH. The effect of temperature on the light emission of fruiting bodies indicated that bioluminescence in M. chlorophos may involve enzymatic reaction(s). The solubilization of bioluminescent components from the fruiting bodies could not be achieved with various surfactants. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
20.
When Chlorella vulgaris 11h, Chlorella vulgaris C-l, Chlamydomonasreinhardtii, Chlamydomonas moewusii, Scenedesmus obliquus, orDunaliella tertiolecta were illuminated in with 0.5 mM NaHCO3,the pH of the medium increased in a few minutes from 6 to about9 or 10. The alkalization, which was accompanied by O2 evolution,was dependent on light, external dissolved inorganic carbon(DIC) as HCO-3, and algae grown or adapted to a low, air-levelCO2 in order to develop a DIC concentrating mechanism. Therewas little pH increase by algae without a DIC concentratingprocess from growth on 3% CO2 in air. Photosynthetic O2 evolutionwithout alkalization occurred using either internal DIC or externalCO2 at acidic pH. The PH increase stopped between pH 9 to 10,but the alkalization would restart upon re-acidification betweenpH 6 and 8. Alkalization was suppressed by the carbonic anhydraseinhibitors, acetazolamide, ethoxyzolamide or carbon oxysulfide.The pH increase appeared to be the consequence of the externalconversion of HCO3 into CO2 plus OH during photosynthesisby cells with a high affinity for CO2 uptake. Cells grown onhigh CO2 to suppress the DIC pump, when given low levels ofHCO3 in the light, acidified the medium from pH 10 to7. Air adapted Scenedesmus cells with a HCO3 pump, aswell as a CO2 pump, alkalized the medium very rapidly in thelight to a pH of over 10, as well as slower in the dark or inthe light with DCMU or without external DIC and O2 evolution.Alkalization of the medium during photosynthetic DIC uptakeby algae has been considered to be part of the global carboncycle for converting H2CO3 to HCO3 and for the formationof carbonate salts by calcareous algae from the alkaline conversionof bicarbonate to carbonate. These processes seem to be a consequenceof the algal CO2 concentrating process.
1Present address: Department of Biology, Faculty of Science,Niigata University, Niigata, 950-21 Japan. 相似文献