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1.
The subcellular localization of leaf peroxidases (EC 1.11.1.7)and their expression in vegetative and flowered plants has beenstudied in Capsicum annuum (var. annuum) in order to assesswhether the expression of new peroxidase isoenzymes can characterizethe floral state which determines the beginning of reproductivedevelopment. The results showed that floral development is accompaniedby a significant increase in the level of soluble (non-sedimentable)leaf peroxidase, independently of leaf position along the internodes,and therefore independently of the leaf age. An analysis ofthe leaf peroxidase isoenzyme patterns along the internodesfor vegetative and flowered plants shows that the increase inperoxidase activity is due to a general increase in the activityof all the pre-existing peroxidase isoenzymes, although isoenzymeB2 and, especially, isoenzyme A1 showed a distinctive and majorincrease in activity. These two isoenzymes are mainly ionically-boundto cell walls, probably in equilibrium with the same isoenzymesmoving freely in the cell-wall free spaces. The differs fromother peroxidase isoenzymes, such as isoperoxidase B6, whichis mainly located in the covalently-bound cell-wall fractionand in mesophyll vacuoles. These results are discussed in thelight of a possible role of cell wall peroxidases as markersof the floral state in Capsicum annuum morphogenesis.Copyright1993, 1999 Academic Press Capsicum, floral state, leaf peroxidases, subcellular localization, vegetative state  相似文献   

2.
Cardiacsarcolemmal (SL) cis-unsaturated fatty acid sensitivephospholipase D (cis-UFA PLD) is modulated by SLCa2+-independent phospholipase A2(iPLA2) activity via intramembrane release ofcis-UFA. As PLD-derived phosphatidic acid influences intracellular Ca2+ concentration and contractileperformance of the cardiomyocyte, changes in iPLA2 activitymay contribute to abnormal function of the failing heart. We examinedPLA2 immunoprotein expression and activity in the SL andcytosol from noninfarcted left ventricular (LV) tissue of rats in anovert stage of congestive heart failure (CHF). Hemodynamic assessmentof CHF animals showed an increase of the LV end-diastolic pressure withloss of contractile function. In normal hearts, immunoblot analysisrevealed the presence of cytosolic PLA2 (cPLA2)and secretory PLA2 (sPLA2) in the cytosol, withcPLA2 and iPLA2 in the SL. IntracellularPLA2 activity was predominantly Ca2+independent, with minimal sPLA2 activity. CHF increasedcPLA2 immunoprotein and PLA2 activity in thecytosol and decreased SL iPLA2 and cPLA2immunoprotein and SL PLA2 activity. sPLA2activity and abundance decreased in the cytosol and increased in SL in CHF. The results show that intrinsic to the pathophysiology of post-myocardial infarction CHF are abnormalities of SL PLA2isoenzymes, suggesting that PLA2-mediated bioprocesses arealtered in CHF.

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3.
The occurrence of multiple forms of glutamine synthetase inStriga hermonthica and other angiosperm root parasites was investigated.The facultative chlorophyllous parasite Melampyrum arvense exhibitedtwo isoenzymes in leaf tissue, the cytosolic component (GS1)comprised less than 30% of total glutamine synthetase. In contrastGS1 was the major component (<70%) in photosynthetic tissueof Striga hermonthica and S. gesnerioides. Only a single isoenzyme(GS1) was detectable in the achlorophyllous root parasites Orobancheand Lathraea and in non-photosynthetic tissue of S. gesnerioides.The kinetic and physical properties of GS1 and GS2 of theseangiosperm parasites were similar to those of the isoenzymesin other non-parasitic angiosperms. Key words: Glutamine synthetase, Angiosperms, Root parasites  相似文献   

4.
Three artificial electron acceptors of different Eo and charge,hexacyanoferrate (III) (K3Fe(CN)6), hexachloroiridate (IV) (K2IrCl6),and hexabromoiridate (IV) (K2IrBr6), were compared with respectto their rate of reduction by roots of Zea mays L., the concomitantproton secretion, and to the effect on plasmalemma depolarization. It has been shown that these plasma membrane impermeable electronacceptors were reduced by a plasmalemma reductase activity.At low concentrations proton secretion was slightly inhibited,at higher concentrations, however, the rate of proton secretionwas stimulated. The root cell plasmalemma showed a transientdepolarization after addition of all three electron acceptors.The depolarization was concentration-dependent for the iridatecomplexes but not for hexacyanoferrate (III). For both iridatecomplexes maximum depolarization was reached at 50 µmoldm–3. A hypothetical model as an explanation of the redox dependentproton secretion will be given. Key words: Hexachloroiridate (IV), hexabromoiridate (IV), hexacyanoferrate (III), plasmalemma redox, membrane potential, Zea mays  相似文献   

5.
Ritchie, R. J. 1987. The permeability of ammonia, methylamineand ethylamine in the charophyte Chara corallina (C. australis).—J.exp. Bot. 38: 67–76 The permeabilities of the amines, ammonia (NH3), methylamine(CH3NH2) and ethylamine (CH3CH2NH2) in the giant-celled charophyteChara corallina (C. australis) R.Br. have been measured andcompared. The permeabilities were corrected for uptake fluxesof the amine cations. Based on net uptake rates, the permeabilityof ammonia was 6?4?0?93 µm s–1 (n = 38). The permeabilitiesof methylamine and ethylamine were measured in net and exchangeflux experiments. The permeabilities of methylamine were notsignificantly different in net and exchange experiments, norto that of ammonia (Pmethylamine = 6?0?0?49 µm s–1(n = 44)). In net flux experiments the apparent permeabilityof ethylamine was slightly greater than that of ammonia andmethylamine (Pethylamine, net = 8?4?1?2 µm s–1 (n= 40)) but the permeability of ethylamine based on exchangeflux data was significantly higher (Pethylamine, exchange =14?1?2 µm s–1 (n = 20)). Methylamine can be validlyused as an ammonium analogue in permeability studies in Chara. The plasmalemma of Chara has acid and alkaline bands; littlediffusion of uncharged amines would occur across the acid bands.The actual permeability of amines across the alkaline bandsis probably about twice the values quoted above on a whole cellbasis i.e. the permeability of ammonia across the permeablepart of the plasmalemma is probably about 12 µm s–1. Key words: Chara, permeability, ammonia, methylamine  相似文献   

6.
褐飞虱对噻嗪酮抗性的遗传分析   总被引:1,自引:0,他引:1  
害虫的抗性遗传特性是影响其抗性发展的一个重要因子,也是制订抗性治理对策的重要依据。我们采用稻茎浸渍法测定了褐飞虱Nilaparvatalugens (Stal)抗性和敏感亲本、正反交(F1、F12、F'2)及回交(BC)后代3龄若虫对噻嗪酮的剂量反应数据,研究了褐飞虱对噻嗪酮的抗性遗传特性。结果表明: 正反交后代的显性度分别为-0.3153(F1)和-0.376 3(F'1),表明抗性遗传为常染色体的不完全隐性;将自交及回交后代的剂量反应数据进行单个主基因假设的卡方(χ2)检验,其卡方值分别为42.11(F2)、5.44 (F'2)及93.57(BC),均大于χ0.05= 15.51(df=8),表明其抗性是多基因控制的。还讨论了褐飞虱对噻嗪酮的抗性治理策略。  相似文献   

7.
Stylar proteins of 13 almond (Prunus dulcis) cultivars withknown S-genotypes were surveyed by IEF and 2D-PAGE combinedwith immunoblot and N-terminal amino acid sequence analysesto identify S-RNases associated with gametophytic self-incompatibility(SI) in this plant species. RNase activities corresponding toSa and Sb, two of the four S-alleles tested, were identifiedby IEF and RNase activity staining. The Sa-RNase band reactedwith the anti-S4serum prepared from Japanese pear (Pyrus serotina);no reaction with the antiserum was observed with the sbRNaseband. When the sa-RNase band was excised from an IEF gel stainedfor RNase activity, subjected to SDS-PAGE, and detected by immunoblotting,it appeared that this band consisted of a single protein thatreacted with the anti-s4serum with Mr of about 28 kDa. With2D-PAGE and silver staining of the stylar extracts, all fourS-proteins could be successfully distinguished from each otherin the highly basic zone of the gel. Although Sb-, Sc-, andSdproteins had roughly the same Mr of about 30 kDa, the Sc-proteinseemed to be slightly smaller than the Sb-protein and slightlylarger than the Saprotein. In 2D-PAGE profiles as well, theSa-protein had Mr of about 28 kDa, apparently smaller than theother three proteins. A bud sport, in which one of the two S-allelesof the original cultivar is impaired, was visualized as a lossof Scprotein, which is consistent with the previous pollinationstudy. All four S-proteins reacted with the anti-S4serum, probablybecause of the differing conformations of these S-proteins inthe IEF and 2D-PAGE gels. The Sa-protein in 2D-PAGE appearedto be identical to Sa-RNase in IEF; both bad the same Mr andwere reactive with the anti-S4-serum. N-terminal amino acidsequence analysis of the four 5-proteins revealed that theywere highly homologous to each other and similar to the 5-RNasesof Malus, Pyrus, Scrophulariaceae, and Solanaceae. Taken together,RNases in the style are strongly suggested to be associatedwith the gametophytic SI of al- mond. This is the first reportidentofiying and characterizing S-RNase in almond. (Received July 11, 1996; Accepted December 26, 1996)  相似文献   

8.
From homogenates prepared from surface-sterilized nodules ofseedlings of Casuarina cunninghamiana grown aeroponically, astrain of Frankia designated HFPCc13 was isolated and has beengrown in pure filamentous culture in a defined synthetic nutrientmedium. Vesicle and sporangium formation can be induced by removalof combined nitrogen from the medium.Frankia strain HFPCc13nodulates young seedlings of C. cunninghamiana and C. equisetifoliawithin three weeks of inoculation with an optimum root mediumpH of 6–7 for nodulation and optimum temperature of 30–35°C. The presence of combined nitrogen in the root mediuminhibits nodulation with NH4+ more inhibitory than NO3.Frankia HFPCc13 does not nodulate Allocasuarina species withinthe same family nor several other possible actinorhizal plantstested. Thus this strain is quite precise in its host specificity.The rate of acetylene reduction was greater in C. cunninghamianathan the closely related species C. equisetifolia. In neitherof these host species were vesicles observed to occur withinthe infected root nodules which had been demonstrated to beactively fixing dinitrogen. Root nodules were shown to be activein acetylene reduction over a range of O2 concentration in thegaseous environment with an optimum at about 20 per cent O2,the ambient PO2 of the air. The mechanism(s) for oxygen protectionof nitrogenase within the filamentous form of Frankia withinthese nodules remains to be explained. Casuarina, Frankia, nodulation, nitrogen fixation  相似文献   

9.
The activity of photosynthesis and mitochondrial respiration,nocturnal organic acid accumulation and water relations wereinvestigated in Prenia sladeniana L. Bol. [malic enzyme (ME)-type]andCrassula lycopodioides Lam. [phosphoenolpyruvate carboxykinase(PEPCK)-type] to compare the physiological responses to waterdeficit in crassulacean acid metabolism (CAM) plants differingin their decarboxylating enzyme systems. Withholding water inhibiteddaytime gas exchange within 2 d while night time CO2gain andmalic acid accumulation remained relatively unchanged in bothspecies. In P. sladeniana, maximum photochemical efficiency(Fv/Fm) and photosynthetic electron transport declined to nearlythe same degree as CO2supply was restricted during drought.Despite limited CO2availability, photosynthetic activity waslargely unaffected in C. lycopodioides, as were mitochondrialproperties. There is no indication of a drought-induced increasein the capability to totally oxidize malate, yielding 4 CO2, in either species. Nevertheless, the enhanced ratio of malateto glycine oxidation may have increased the in vivo capabilityfor malate oxidation in P. sladeniana. Although pressure potentialwas maintained throughout the experiment in both species, activeosmotic adaptation occurred only inP. sladeniana. The observeddecrease in photosynthetic and mitochondrial activity may haveresulted from the large increase in osmotic concentration inthis species. Copyright 2000 Annals of Botany Company Chlorophyll fluorescence analysis, Crassula lycopodioides Lam., crassulacean acid metabolism, citric acid, gas exchange, malic acid, mitochondria, photosynthetic electron transport, Prenia sladeniana L. Bol., water relations  相似文献   

10.
Effects of atmospheric CO2 enrichment to a level above 600 parts10–6 on leaf and canopy gas exchange characteristics wereinvestigated in Trifolium repens, using an open system for gasexchange measurement. The cuvettes of the system served as growthchambers, allowing continuous measurement in a semi-controlledenvironment of ±350 and ±600 parts 10–6CO2, respectively. Carbon balance data were compared with cropyield and effects on the canopy level were compared with measuredleaf responses of photosynthesis and stomatal behaviour. Photosyntheticstimulation by high CO2 was stronger at the canopy level (103%on average) than for leaves (90% in full light), as a consequenceof accelerated foliage area development. The latter increasedabsolute water consumption by 16%, despite strong stomatal closure.The overall result was a 63% improvement in canopy water useefficiency (WUE), while leaf WVE increased almost 3-fold insaturating light. The stomatal response was such that, whilethe internal CO2 concentration in the leaf, ch increased withrising atmospherical CO2 concentration, ca, ci/ca was somewhatdecreased. Total canopy resistance, Rc, was generally lowerat high CO2 levels, despite higher leaf resistance. Higher canopyCO2 loss at night and faster light extinction in a larger-sizedhigh CO2 canopy were major drawbacks which prevented a furtherincrease in dry matter production (the harvest index was increasedby a factor 1.83). Key words: CO2 enrichment, canopy CO2 exchange, carbon balance, water use efficiency, leaf and canopy resistance  相似文献   

11.
Multiple Forms of the Constitutive Wheat Cinnamyl Alcohol Dehydrogenase   总被引:1,自引:0,他引:1  
Three cinnamyl alcohol dehydrogenase (CAD) isoenzymes were separatedfrom etiolated wheat seedlings (Triticum aestivum L.) and examinedby native gel electrophoresis. Two of these enzymes (CAD-1 andCAD-2) were purified to apparent homogeneity. They exhibiteda marked difference in substrate affinity. On sodium dodecylsulphate-acrylamide gel the isolated isoenzymes showed onlyone protein band each with an Mr 45000 and 40000 daltons, respectively,whereas on native gel two bands were identified for each protein.Isoenzymes from a variety of diploid, tetraploid, and hexaploidwheats were compared. The results indicated that the CAD polymorphismcould be genetically determined. Key words: Cinnamyl alcohol dehydrogenase, lignin, Triticum aestivum L  相似文献   

12.
A Cl current activated by extracellular acidification, ICl(pHac), has been characterized in various mammalian cell types. Many of the properties of ICl(pHac) are similar to those of the cell swelling-activated Cl current ICl(swell): ion selectivity (I > Br > Cl > F), pharmacology [ICl(pHac) is inhibited by 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS), 1,9-dideoxyforskolin (DDFSK), diphenylamine-2-carboxylic acid (DPC), and niflumic acid], lack of dependence on intra- or extracellular Ca2+, and presence in all cell types tested. ICl(pHac) differs from ICl(swell) in three aspects: 1) its rate of activation and inactivation is very much more rapid, currents reaching a maximum in seconds rather than minutes; 2) it exhibits a slow voltage-dependent activation in contrast to the fast voltage-dependent activation and time- and voltage-dependent inactivation observed for ICl(swell); and 3) it shows a more pronounced outward rectification. Despite these differences, study of the transition between the two currents strongly suggests that ICl(swell) and ICl(pHac) are related and that extracellular acidification reflects a novel stimulus for activating ICl(swell) that, additionally, alters the biophysical properties of the channel. cell swelling-activated chloride current; patch clamp; pH  相似文献   

13.
We report, for the epithelialNa+ channel (ENaC) in A6 cells,the modulation by cell pH (pHc)of the transepithelial Na+ current(INa), thecurrent through the individual Na+channel (i), the openNa+ channel density(No), and thekinetic parameters of the relationship betweenINa and theapical Na+ concentration. Thei andNo were evaluatedfrom the Lorentzian INa noise inducedby the apical Na+ channel blocker6-chloro-3,5-diaminopyrazine-2-carboxamide.pHc shifts were induced, understrict and volume-controlled experimental conditions, byapical/basolateral NH4Cl pulses orbasolateral arrest of theNa+/H+exchanger (Na+ removal; block byethylisopropylamiloride) and were measured with the pH-sensitive probe2',7'-bis(2-carboxyethyl)-5(6)-carboxyfluorescein. Thechanges in pHc were positivelycorrelated to changes inINa and theapically dominated transepithelial conductance. The sole pHc-sensitive parameter underlyingINa wasNo. Only thesaturation value of theINa kinetics wassubject to changes in pHc.pHc-dependent changes inNo may be causedby influencingPo, the ENaC openprobability, or/and the total channel number,NT = No/Po.

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14.
Exogenous gibberellin A3(GA3) reduced the number of leaf nodesat flowering and time to flowering and increased the stem heightat flowering in three genotypes of spring rape (Brassica napusvar.annua L.). The responses to GA3were similar to those forlong days (LD) and low-temperature treatments, suggesting thatthe effect of photoperiod and the vernalization response areprobably mediated through gibberellins. The response to exogenousGA3was greatest in non-cold-treated plants in short days (SD)suggesting that endogenous GAs are limiting in these conditions.CCC, an inhibitor of gibberellin biosynthesis, caused a smallincrease in the number of leaf nodes at flowering and time toflowering and a small decrease in the stem height at flowering,but unexpectedly, its effect was hardly influenced by the applicationof exogenous GA3. Genotypes that showed the clearest responsesto the treatments with regard to the number of leaf nodes atflowering and time to flowering did not show the clearest responseswith regard to the stem height at flowering; the pattern ofresponses of the number of leaf nodes at flowering and timeto flowering was distinct from that of stem height at flowering.This indicates that flower formation and stem elongation areseparable developmental processes which may be controlled bydifferent endogenous gibberellins, different levels of a specificendogenous gibberellin, or different responses to gibberellin.Copyright 1999 Annals of Botany Company Brassica napus var. annua, gibberellin, photoperiod, spring rape, vernalization.  相似文献   

15.
邱明生  赵志模 《昆虫学报》1999,42(2):145-149
研究了环境因子对角倍蚜Schlechtendalia chinensis (Bell) 秋迁蚜生殖和雌性蚜发育的影响。温、湿度单因子试验表明,秋迁蚜在26℃和80%RH条件下有最大生殖量;温、湿度对秋迁蚜生殖量的影响均符合开口向下的二次抛物线变化趋势,极端温、湿度会导致生殖量的下降。采用三元一次正交组合设计,研究了环境温度(X1)、湿度(X2)和光照强度(X3)三因子不同水平组合对雌性蚜发育的影响,表明温度是影响发育历期的主要因子,其次是光照强度,最后是湿度。因此,适当高温、强光照条件可以加快雌性蚜发育;而适当高湿条件可以降低雌性蚜的发育速率而延长其发育历期。在人工培育角倍蚜生产中,创造有利于秋迁蚜生殖的温、湿度条件可以使秋迁蚜产下较多的越冬侨蚜;在适当降低温度、增加湿度的阴暗条件下贮留雌性蚜可以适当延长其发育,以使角倍蚜与盐肤木在物候上达到最佳吻合。  相似文献   

16.
A specific inhibiting effect of CO2 on cell division in Saccharomycescerevisiae (Meyen) was shown. Two strains of S. cerevisiae weregrown in chemically-defined media in specially-designed pressurechambers equipped with sensitive pressure-measuring devices.The chambers were pressurized with 40 psi of N2 or CO2. Inhibitionof cell division and of production of new buds was not causedby N2 but was caused by CO2 when either endogenously producedor added. In contrast, metabolic production of CO2 was unaffectedby endogenously-produced pressures which totally inhibited celldivision. Bud formation and new-cell formation (cell division) were almosttotally inhibited by 40 psi of added CO2 when compared withaerated cultures. The DNA content per cell, however, was nearlytwice as great in the CO2-treated cultures as in the controls.Thus inhibition of cell division in S. cerevisiae must occurby some mechanism other than by inhibition of DNA replication. (Received January 5, 1971; )  相似文献   

17.
Gibberellic acid (GA3) promotes parthenocarpic fruit developmentand is used commercially to increase fruit set in many crops.However, fruit size is usually smaller than that of pollinatedfruit. The purpose of this work was to determine the anatomicalbasis for differences in fruit size between pollinated and GA3-inducedparthenocarpic blueberry (Vaccinium asheiReade) fruits. Freshweights at ripening averaged 1.6 and 2.5 g for GA3-treatedvs.pollinated fruits, respectively. In both pollinated and GA3-treatedfruits, mesocarp cell number comprised about 75% of the totalpericarp cell number, and increased from  相似文献   

18.
寄主对桔小实蝇耐寒性的影响   总被引:13,自引:2,他引:13  
任璐  陆永跃  曾玲  庞淑婷 《昆虫学报》2006,49(3):447-453
为了研究寄主营养对桔小实蝇耐寒性的作用,测定了以15种果蔬饲养的桔小实蝇1日龄蛹的过冷却点(supercooling points,SCP); 再选取南瓜、西红柿、柑桔、番石榴和杨桃等5种果蔬,测定了桔小实蝇3龄老熟幼虫、1日龄蛹、3日龄蛹、5日龄蛹、7日龄蛹和雌雄成虫的过冷却点,并观察了1日龄蛹的低温存活力。结果表明:(1)15种果蔬饲养所得的桔小实蝇1日龄蛹SCP均值在-11.03℃~-13.17℃,不同寄主发育的桔小实蝇SCP值存在显著性差异,其中以取食蒲桃的最高,为-11.03℃,取食苦瓜的最低,为-13.17℃。(2)5种果蔬饲养所得的桔小实蝇各虫态的SCP均值存在极显著差异(F(4,863)=35.6,P<0.01); 同一寄主上的桔小实蝇不同虫态之间SCP均值也达到极显著性差异(F(6,863)=392.9,P<0.01); 且寄主和发育龄期之间存在着极显著的交互作用(F(24,863)=9.4,P<0.01)。(3)桔小实蝇各发育阶段,SCP值表现一定变化: 老熟幼虫发育至1日龄蛹,SCP值变化不大; 蛹发育至3、5和7天过冷却能力明显增强,降至-20℃左右,但他们之间没有明显区别; 羽化后3~5天的成虫SCP值又升高至-10℃左右。老熟幼虫、1日龄蛹和2~3日龄成虫与3日龄、5日龄和7日龄蛹的SCP值之间有显著性差异。(4)将5种果蔬饲养所得的桔小实蝇1日龄蛹置于6℃和-3℃下进行较长时间(1~8天)和较短时间(1~8 h)的低温处理,发现番石榴、杨桃和南瓜发育的蛹经低温处理后的校正羽化率较西红柿和柑桔发育的蛹高; 同样在0℃、3℃、6℃和9℃处理(2天)的实验中,得出相似的结果。因此,本实验结果表明桔小实蝇幼虫由于生活寄主的不同使得其下一代蛹的耐寒性产生了差异,引起其差异的原因值得进一步研究。  相似文献   

19.
The effects of elevated atmospheric CO2 concentrations on theecophysiological responses (gas exchange, chlorophyll a fluorescence,Rubisco activity, leaf area development) as well as on the growthand biomass production of two poplar clones (i.e. Populus trichocarpax P. deltoides clone Beaupré and P. x euramericana cloneRobusta) were examined under open top chamber conditions. Theelevated CO2 treatment (ambient + 350 µmol mol-1) stimulatedabove-ground biomass of clones Robusta and Beaupré afterthe first growing season by 55 and 38%, respectively. This increasedbiomass production under elevated CO2 was associated with asignificant increase in plant height, the latter being the resultof enhanced internode elongation rather than an increased productionof leaves or internodes. Both an increased leaf area index (LAI)and a stimulated net photosynthesis per unit leaf contributedto a significantly higher stem biomass per unit leaf area, andthus to the increased above-ground biomass production underthe elevated CO2 concentrations in both clones. The larger LAIwas caused by a larger individual leaf size and leaf growthrate; the number of leaves was not altered by the elevated CO2treatment. The higher net leaf photosynthesis was the resultof an increase in the photochemical (maximal chlorophyll fluorescenceFm and photochemical efficiency Fv/Fm) as well as in the biochemical(increased Rubisco activity) process capacities. No significantdifferences were found in dark respiration rate, neither betweenclones nor between treatments, but specific leaf area significantlydecreased under elevated CO2 conditions.Copyright 1995, 1999Academic Press Biomass, chlorophyll a fluorescence, elevated CO2, growth, Populus, poplar, photosynthesis, respiration, Rubisco  相似文献   

20.
Carbonic anhydrase (CA) activity was detected in homogenatesfrom Anabaena variabilis ATCC 29413, M-2 and M-3, but not inthe suspension of the intact cells. Activity was higher in cellsgrown in ordinary air (low-CO2 cells) than in those grown inair enriched with 2–4% CO2 (high-CO2 cells). Fractionationby centrifugation indicated that the CA from A. variabilis ATCC29413 is soluble, whereas both soluble and insoluble forms existin A. variabilis M-2 and M-3. The addition of dithiothreitoland Mg2 $ greatly decreased the CA activity of A. variabilisATCC 29413. The specific activity of the CA from A. variabilis ATCC 29413was increased ca. 200 times by purification with ammonium sulfate,DEAE-Sephadex A-50 and Sephadex G-100. Major and minor CA peaksin Sephadex G-100 chromatography showed respective molecularweights of 48,000 and 25,000. The molecular weight of the CAdetermined by polyacrylamide disc gel electrophoresis was 42,000?5,000.The activity of CA was inhibited by ethoxyzolamide (I50=2.8?10-9M), acetazolamide (I50=2.5?10-7 M) and sulfanilamide (I50=2.9?10-6M). (Received January 5, 1984; Accepted April 26, 1984)  相似文献   

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