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1.
The influence of different light qualities on chlorophyll contentand growth of tissue cultures from Crepis capillaris (L.) WALLR. Tissue cultures from Crepis capillaris growing on media (M1; M2 ; M2-E) formed chlorophyll and intact chloroplasts onlyin the short wave length region of the visible spectrum (350550nm). In red light (600700 nm) as well as in darknessthey lost their chlorophyll after 810 weeks. The growth of Crepis-cultures was strongly influenced by lightand the nitrogen of the medium. The highest increase in freshweight (425485% increase in 3 weeks) was attained inred light or in darkness on M2 by cultures which had lost theirchlorophyll completely. M2 contains nitrates, ammonium saltsand amino acids. In contrast, the increase in fresh weight ofgreen cultures growing on M2 in blue or white light was considerablylower (155180% increase in 3 weeks). Omission of amino acids, (M2-E), resulted in the reduction ofthe growth (increase of fresh weight in 3 weeks: 120%) of thechlorophyll-free cells growing in the dark. Green cultures behaveddifferently on M2-E. In white light they attained an increasein fresh weight of 245%. This suggests that the growth promotingeffect of the amino acids can be replaced by light. Results with cultures growing on M1, which contains neitherammonium salts nor amino acids, point in the same direction.Green cultures in white or blue light grew better (90100%increase in fresh weight in 3 weeks) on this "deficient" mediumthan chlorophyll-free tissues in red light or in darkness (2030%increase in fresh weight in 3 weeks). Some aspects of thesefindings which concern the effect of light on growth are discussed. (Received November 28, 1969; ) 相似文献
2.
Unno Keiko; Ando Ichiro; Hagima Naoko; Yokogaki Shuichi; Koike Chieko; Okada Shoji 《Plant & cell physiology》1992,33(7):963-969
The effects of deuterium (D) on Chlorella ellipsoidea C-27 wereinvestigated. Cells grown in a medium prepared with deuteriumoxide (D2O) showed pronounced delays in cell growth and division;the length of a cell cycle in medium with 100 mol% D2O was morethan 5 times longer than that in medium prepared in H2O Thedelay caused by D2O was not overcome by either indoleaceticacid or kinetin. The biological and ultrastractural characteristicsof deuterated .Chlorella (D-Chlorella) cells were examined.The responses of D-Chlorella to cell wall-digesting enzymesdid not differ from those of normal (H-Chlorella) cells. D-Chlorellacells were enlarged, and cellular components, such as proteins,nucleic acids, lipids and ATP, were present in larger quantitiesthan those in H-cells. The chloroplast of D-Chlorella was enlarged,but the levels of component photosynthetic pigments were significantlyreduced. By contrast, mitochondria of D-Chlorella were smallerthan those of H-cells. These changes in levels of cellular componentsand in the sizes of organelles seem to be unique to deuteration. (Received May 13, 1992; Accepted July 28, 1992) 相似文献
3.
The availability of light, CO2 and NH4-N interacted to controlbuoyancy and growth of the gas vacuolate blue-green alga, Anabaenaflos-aquae. At high light intensities algal growth rates werehigh; however, the alga was non-buoyant regardless of the availabilityof CO2 or NH4-N. The mechanism for buoyancy loss involved increasedcell turgor pressures at higher light intensities which resultedin collapse of gas vacuoles. At lower light intensities algalgrowth rates and cell turgor pressures were reduced and buoyancywas controlled by the availability of CO2 and inorganic nitrogen.Carbon dioxide limitation increased buoyancy, while reducedinorganic nitrogen availability reduced buoyancy. Mechanismsfor buoyancy regulation at low light intensities involved changesin cellular C/N ratios which appeared to affect the rate ofsynthesis and accumulation of protein-rich gas vacuoles. Algalspecific growth rates were combined with buoyancy data to forma single index (µbloom) to the rate of surface bloom formationof A.flos-aquae as a function of the availability of light,CO2 and NH4-N. The bloom formation index was enhanced with decreasedavailability of light and CO2, and increased availability ofNH4-N. 相似文献
4.
The Inhibition of Growth in Higher Plants by a Homologous Series of Guanidines and its Reversal by Spermine 总被引:1,自引:0,他引:1
The effects of guazatine, synthalins A and B and a homologousseries of aliphatic monoguanidines on the growth of cress, barleyand oat seedlings, and apple cell suspension cultures have beenstudied. In the homologous series of aliphatic monoguanidines[NH2C(=NH)NH(CH2)x1CH3] greatest inhibition was foundwith x = 8-10 for cress, barley and oats and x= 1014for apple cells. Spermine partially reversed the inhibitionin the light for cress and barley but in the dark no reversalwas found. Technical guazatine inhibited growth to a greaterextent than pure guazatine, and was comparable in toxicity tosynthalin B in cress, barley and oats. Reversal by spermineof inhibition due to guazatine and synthalin B was greater inthe light than in the dark in these plants. Calcium ions didnot reverse the toxicity of guazatine, synthalin B or dodine.Reversal of the inhibition by guazatine, synthalin B and dodineof the growth of the apple cells was considerably greater withspermine than with spermidine. Lepidium sativumcress, Hordeum vulgarebarley, Avena sativaoat, Malus sylvestrisapple, guanidines, guazatine, synthalins, dodine, spermine, spermidine 相似文献
5.
Takamiya Ken-ichiro; Satoh Kazuyoshi; Okuyama Tokuji; Uchino Ryosho; Shioi Yuzo; Doi Michio; Takaichi Shinichi 《Plant & cell physiology》1993,34(7):985-990
The cellular level of cytochrome cd1, the nitrite reductaseof the aerobic photosynthetic bacterium Roseobacter denitrificans,increased considerably when the cells were grown aerobicallyunder white light. The action spectrum for the increase, determinedboth spectroscopically and immunologically, revealed that greenlight at 561 nm was most effective, while blue light between400 and 500 nm was fairly effective. Red and far-red light (650900nm) absorbed by the bacterio-chlorophyll had no effect, eventhough bacteriochlorophyll and carotenoids were formed normallyduring the growth of cells. Diphenylamine, an inhibitor of thebiosynthesis of carotenoids abolished the increase in levelsof the cytochrome, a result that suggests that a carotenoid(s)was responsible for this phenomenon. The bulk carotenoids seem,however, to be unlikely the candidates for the photoreceptorsbecause they did not accumulate in the light-grown cells. Attemptsto detect archaerhodopsin, 11-cis and all-trans retinal by immunologicalor HPLC analysis were unsuccessful. Although we failed to identifythe photoreceptor, it is clear that R. denitrificans has a green-lightsignal-transduction system that controls the expression of cytochromecd1. (Received April 19, 1993; Accepted July 12, 1993) 相似文献
6.
The influence of varying light intensity and quality on thecarbon labelling patterns in Rumex vesicarius (a C3 plant),Setaria italica (a malate-formingC4 plant), and Amaranthus paniculatus(an aspartate-forming C4 plant) was studied. In A. paniculatusand B. vesicarius blue light decreased the transfer of radioactivityto sugars and starch but in S. italica only slightly decreasedradioactivity in sugar phosphates, sucrose, and insolubles.Negligible transfer was observed from the C4 acids to sugarphosphates, sucrose, and starch under dim blue-green and blue-yellowlights in S. italica and A. paniculatus. Blue light favouredthe formation of malate, aspartate, and alanine in all threeplants. The differential effect of blue and red light suggesteda variation in the mechanisms of C4-photosynthesis in Setariaand Amaranthus. Leaves of S. italica and A. paniculatus were allowed to photosynthesizein 14CO2 for 5 s and then the distribution of the labelled productsbetween the mesophyll and the bundle sheath cells was determinedduring subsequent photosynthesis in 12CO2. Malate and aspartatewhich appeared initially in the mesophyll layer moved rapidlyinto the bundle sheath cells. Phosphoglyceric acid originatingin the bundle sheath moved swiftly to the mesophyll layer. Sugarphosphates were recovered from both the mesophyll and the bundlesheath cells. Most of the starch was found in the bundle sheathcells while sucrose and alanine were localized in the mesophyllcells. 相似文献
7.
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
8.
在高CO2浓度下生长的小麦对棉铃虫生长发育和繁殖的影响 总被引:7,自引:3,他引:4
通过室内饲养实验研究了在高CO2浓度(738.8±25.7μL/L)中生长的小麦对棉铃虫 Helicoverpa armigera (Hübner)生长发育,繁殖以及营养效应的影响。结果表明: (1)取食高CO2浓度大气中生长的麦粒的棉铃虫对食料的取食量和粪便排泄量增加,与对照相比,取食量和粪便排泄量分别增加46.3%(P<0.05)和37.8%;(2)大气CO2浓度增加影响了麦粒中的营养成分的含量,其中,可溶性蛋白、游离氨基酸、葡萄糖和总糖的含量及碳氮比(C∶N)都显著增加,果糖和粗蛋白的含量都显著降低;(3)大气 CO2浓度升高所导致的麦粒营养成分的变化影响了棉铃虫幼虫的食物利用效率,与对照组相比,棉铃虫幼虫对食物的毛转化率和净转化率分别降低27.2%和25.4%,对食物的相对取食率则显著提高58.8%(P < 00.1)。据此推测,未来高CO2浓度的大气环境会降低春小麦的营养价值,从而影响棉铃虫的生长发育,加重其对小麦的危害。 相似文献
9.
Mutants deficient in phosphoglycolate phosphatase (PGPase) requireelevated levels of CO2 for growth in the light and cannot growwhen photorespiration occurs. Revertants, namely, double mutantscapable of growth under air without restoration of the missingPGPase activity, might be expected to have secondary mutationsthat reduce or eliminate photorespiration. Nineteen revertantswere selected from a culture of a PGPase-deficient mutant ofChlamydomonas reinhardtii (pgp-1-18-7F) after a second mutagenesisthat involved treatment with 5-fluorodeoxyuridine and ethylmethanesulfonate. There were significant differences in thephotosynthetic affinity for CO2 among revertant cells grownunder 5% CO2. Eight revertants had five times higher photosyntheticaffinity for CO2 than that of wild type 2137 cells grown under5% CO2, resembling air-adapted wild-type cells, whereas fourrevertants had less than half the affinity for CO2 of the wildtype. In all of the revertant cells with higher affinity grownin 5% CO2, the rates of photosynthesis under levels of CO2 belowthose in air were apparently higher than that of the wild type,whereas the rates under CO2-saturating conditions were lowerthan that of wild type, indicating that the efficiency of photosynthesisunder air was significantly improved in these revertants. Inaddition, some revertants had a photosynthetic capacity anda growth rate higher than those of the wild type, without anyincreased photosynthetic affinity for CO2. (Received July 7, 1994; Accepted November 5, 1994) 相似文献
10.
Pathway of dark inorganic carbon fixation in two species of diatoms: influence of light regime and regulator factors on diel variations 总被引:2,自引:0,他引:2
Planktonic algae submitted to vertical mixing with a short periodicitycommute many times a day from low to high irradiance levels.To study the influence of this light periodicity, two diatoms,Skeletonema coslatum and Nitzschia turgiduloides, were cultivatedunder alternating conditions of 2 h light/2 h dark (2 h/2 h),simulating vertical mixing in the natural environment. Two otherlight regimes were used: continuous light (CL) and alternatecycles of 12 h light/12 h dark (12 h/12 h). Products synthesizedin the dark by S.costmum during 60 s incubation for 2 h/2 hculture or during 5 min for 12 h/12 h culture were determined.They were essentially sugars, malate, aspartate and glyceratefor 2 h/2 h cells and 12 h/12 h cells taken at the beginningof the light period. In contrast, 12 h/12 h cells taken duringthe darkness or in the middle of the light period and set inthe dark synthesized only amino acids. Our results corroborateprevious reports on dark CO2 fixation via phosphoenolpyruvatecarboxykinase (PEPCKase, enzyme allowing the fixation of CO2on PEP and the synthesis of amino acids) with involvement ofa substrate synthesized during the light period, but demonstratethat incorporation also occurs by the C-3 pathway (pathway responsiblefor the major CO2 fixation in the light) in the very early stagesof the dark period. Another important result highlighted bythis study is the appreciable rate of dark fixation: on average6.7, 8.3 and 12.7% of photosynthesis at saturating photon fluxdensity for N.turgiduloides cultivated under 2 h/2 h, CL and12 h/12 h regime respectively and nearly 12% for S.costatumin the 2 h/2 h light regime. Variation of dark fixation wasinvestigated as a function of hour in the two species. Skeletonemacostatum cells submitted to the 2 h/2 h cycle show a constantrate of light-independent assimilation throughout the day. Bycontrast, both N.turgiduloides grown under the 12 h/12 h or2 h/2 h regime and S.costatum cultured under the 12 h/12 h cycleundergo fluctuations in the rate of dark fixation over the light/darkcycle. The mean dark fixation rate is controlled by the lengthof the photoperiod or the frequency of light fluctuations, dependingon species. We argue that this phenomenon must be taken intoconsideration in primary production calculations. Dependingon whether they are synthesized at the beginning or at the endof the light period, products are somewhat different and therate of fixation varies. This leads us to suggest that the pathwayof dark fixation may be regulated by at least two factors: amountof available substrate and enzyme (RuBPCase and PEPCKase) activityand/or amount. 相似文献
11.
Pesheva Iskra; Kodama Minoru; Dionisio-Sese Maribel L.; Miyachi Shigetoh 《Plant & cell physiology》1994,35(3):379-387
When air-grown cells of Chlorococcum littorale was enrichedwith CO2, growth was enhanced after a lag period of one to twodays at 20% CO2, and 3 to 6 days at 40% CO2. Changes in therate of photosynthesis measured as oxygen evolution and CO2fixation, were similar to those observed for growth. Duringthe initial inhibition of photosynthesis in 40% CO2, the activityof PSII was suppressed. In contrast, PSI activity was greatlyenhanced. Air-grown cells of C. littorale possessed comparatively highcarbonic anhydrase (CA) activity which was localized insidethe cells and on the cell surface. Under high CO2 concentrationsextracellular CA activity was greatly suppressed and intracellularactivity almost completely abolished. Phosphoenol pyruvate carboxylaseactivity was also suppressed in high CO2-grown cells. Ribulose-l,5-bisphosphatecarboxylase activity was higher in high-CO2 grown cells thanin air-grown cells. The above results indicated that the lagphase induced by 40% CO2 was due to suppression of PSII activity.
1Part of this work was reported in the International PhotosynthesisCongress, Nagoya, 1992. 相似文献
12.
The photoautotrophic culture of chlorophyllous cells 总被引:2,自引:0,他引:2
Photosynthesis in chlorophyllous cells in heterotrophic cultureswas investigated. Chlorophyllous cells from the amur cork-tree,scotch broom and tobacco, all of which had relatively high chlorophyllcontents (70 to 120 µg/g fresh weight) were selected throughoutcallus induction and cell subculture. When cultured under variouslight intensities, growth was stimulated by increases in lightintensity. This stimulation depended on the chlorophyll contentsof the cells. It disappeared on the addition of photosynthesisinhibitors (DCMU or 2-chloro-4,6-bis(ethylamino)-s-triazine).These phenomena indicate that photosynthesis accounted for athird to a half of cell growth under strong illumination. These heterotrophic cultures were then developed as autotrophiccultures. When these chlorophyllous cells were cultured withaeration using CO2-enriched air in the light condition, thescotch broom and tobacco chlorophyllous cells grew photoautotrophically.Nearly the same amount of growth as with 3% sucrose in the darkwas observed in an autotrophic culture with aeration using aircontaining 1% CO2. The green tobacco cells have been subculturedautotrophically for about one year. (Received November 28, 1977; ) 相似文献
13.
Pre-illumination of methionine-supplemented medium enhancedthe inactivation of the light dependent methionine sensitivemutant cells of Chlamydomonas reinhardtii and, to a lesser extent,the wild-type cells, confirming that the photodamage is dueto production of toxic produces) in the medium. Exogenouslyadded catalase protected the mutant cells from growth inhibition.Starch gel electrophoresis showed lower catalase activity inthe mutant cells than the wild type. Catalase activity whichwas followed by measuring O2 evolution after the addition ofH2O2 to the cell suspensions was consistently lower in the mutantthan the wild type. The results indicate that light sensitivityin the presence of methionine expressed by this mutant is dueto reduced activity of catalase. (Received August 31, 1989; Accepted October 9, 1989) 相似文献
14.
Transfer of algal cells of Chlorella regularis from 3% CO2 inair into ordinary air in the light increased external carbonicanhydrase (CA) activity as well as photosynthetic affinity forCO2 by several-fold within 2 h. Since no noticeable differencewas observed in CA activity between intact cells and cell homogenates,CA seemed to be mainly localized on the cell surface. Changesin CA activity and K?(CO2) of photosynthesis were not observedin the dark. CA induction was 50%-inhibited by incubation with10 µM DCMU during adaptation of high-CO2 cells to air,whereas it was considerably suppressed when high-CO2 cells preincubatedwith DCMU in the light for 6 h or without DCMU in the dark for24 h were used. The change in K?(CO2) of photosynthesis wasonly slightly affected by DCMU. Uncoupler like carbonylcyanide-m-chlorophenyl-hydrazone(CCCP) and inhibitors of mitochondrial respiration (KCN plussalicylhydroxamic acid) suppressed CA induction during adaptationof high-CO2 cells to low CO2 conditions. These results suggest that photosynthesis is not essential forCA induction in Chlorella regularis when some amounts of photosyntheticproducts are previously stored in the cells and respirationis active. A decrease in K?(CO2) of photosynthesis during adaptationfrom high to low CO2 was mostly independent on photosynthesis.However, light is essential for both phenomena. (Received July 16, 1990; Accepted January 21, 1991) 相似文献
15.
The interaction of light, gibberellic acid (GA3), and phlorizinin the growth of lettuce (Lactuca sativa L. cv. GrandRapids) hypocotyls was investigated. At all concentrationsof GA3, phlorizin enhanced GA3-induced growth at luminous intensitiesabove 50 ft-c (continuous light). Without GA3, phlorizin hadno effect on hypocotyl growth in the light but it inhibitedgrowth in the dark. Both seedlings and hypocotyl sections respondedto phlorizin in the presence of GA3. There was no iteractionbetween phlorizin and KCl. Water-growth was severly inhibitedby light. GA3,-induced growth was slightly inhibited by light,and then only at luminous intensities above 50 ft-c. Thus, relativeto H2O-growth, GA3-induced growth increased with increasingluminous intensity up to 450 ft-c, where it reached saturation.It seems that a synergism may exist between light and GA3 aswell as between phlorizin and GA3. Lactuca sativa L, lettuce, hypocotyl elongation, gibberellic acid, phlorizin, light 相似文献
16.
Cratoneuron filicinum, a drought-sensitive moss, and Tortularuralis, a drought-tolerant moss, fix CO2 non-autotrophicallyat a rate of about 1.2 and 2.2 µmol h1 g1dry wt. respectively. During drying, T. ruralis fixes CO2 atan undiminished rate until the tissue loses about 60% of theinitial fresh weight. Thereafter, CO2 fixation rapidly declinesto zero. Dark CO2 fixation by C.filicinum declines steadilyduring the dehydration period. On rehydration, dark CO2 fixationis resumed immediately in T. ruralis but not in C.filicinum.When dried T. ruralis is equilibrated with an atmosphere ofnearly 100% relative humidity, its weight increases to about40% of the original fresh weight and dark CO2 fixation resumesat a rate about 60% of the fresh moss. In C.filicinum thereis only a small increase in weight and little CO2 fixation inthe dark. The non-autotrophically fixed carbon, in both mossesstudied, is incorporated into amino acids (more than 60% ofthe total, mainly into aspartate, alanine and glutamate) andorganic acids (less than 40% of the total, mainly into malate).It is suggested that on rehydration immediate availability ofNADPH, known to be produced by transhydrogenation from NADHduring dark CO2 fixation, may be an important factor in therepair of drought-induced cellular damage by reductive biosynthesisof membrane components and other cellular constituents. Key words: Mosses, Dehydration, Rehydration, Dark CO2 fixation, Amino acids, Organic acids, NADPH, Drought tolerance. 相似文献
17.
- Using Chlorella ellipsoidea as material, investigations weremade of the effects of ultraviolet irradiation upon variousactivities of cells at different developmental stages in theirlife cycle. Cell activities investigated were photosynthesis,respira tion, over-all growth, modes of synchronous growth andcell division as well as the formation of nucleic acids. Theu. v.- light applied was 30 µµW/cm2in intensityand 2537 Å in wavelength.
- The most u. v.-sensitive wasthe over-all growth activity, andin this respect the irradiationapplied at the L2-stage wasmore inhibitive than that givenat the D-stage. The next mostvulnerable was the photosyntheticactivity, the sensitivitybeing the same in the D- and L-cells.The most resistant towardu.v. was the endogenous respirationof D-cells followed by theirrespiration using exogenous glucoseas substrate. The L2-cellsappeared to be unable to use exogenousglucose as substrateof respiration, but their endogenous respirationwas considerablystronger than that of D-cells, and its u. v.-sensitivitywasthe same as that of glucose respiration of D-cells.
- WhenD-cells were u. v. irradiated immediately before the startofsynchronous culture, growth and cell division as well astheformation of DNA and RNA were retarded in proportion totheu. v.-dose applied. The division number (n) was normal (around4) at lower u.v.-doses (1-2 minute irradiation), but was reducedto a half (about 2) at a higher dose.
- When, during the synchronousculture, 1-minute u.v.- irradiationwas applied at various stagesof the ripening phase, the divisionwas retarded, but the cells,after attaining an abnormally largesize, divided into about8. If the irradiation was given atthe L4-stage, the divisionnumber was practically unmodified(n=4.5), although the divisionwas somewhat retarded comparedwith that of the control culture.When a 1-minute irradiationwas given at the L2-stage, thereoccurred an apparent stimulationof DNA- and RNA-formation,a phenomenon which corresponds tothe production of a largernumber of daughter cells than itwas the case in control cultures.
- Thus the cells which were moderately u.v.-irradiated at differentstages of synchronous culture were able to complete their lifecycle, but later a certain portion of irradiated cells becameunable to grow normally.
18.
The enhancement of algal growth by organic substrate assimilationis a common laboratory observation, yet few studies have addressedthe interaction of dissolved organic compounds and environmentalfactors for controlling the relative contribution of heterotrophyand autotrophy to the nutrition of these algae. The effectsof light intensity and glycerol addition on the growth, cellvolume, pigmentation, and carbon uptake of the facultative heterotroph,Pyrenomonas salina Santore, were examined. Glycerol additionto cultures growing at a limiting light intensity increasedthe growth rate, increased the average cell volume and cellularstarch content, decreased the cellular phycoerythrin to chlorophyll ratio, and had no effect on the CO2 fixation rate cell1.Glycerol addition to cultures growing at a moderate light intensitythat was saturating for photo-autotrophic growth increased theaverage cell volume and cellular starch content but had no effecton the CO2 fixation rate cell1. The results indicatethat autotrophy was the major process for carbon acquisitionduring the growth of P. salina, but that carbon acquisitionfrom glycerol catabolism also was used to partially supportgrowth of the alga at the limiting light intensity. In addition,glycerol presumably was used to fulfill the energy and/or reductantrequirements of the alga, and to increase the reserve carbohydrate(starch).
1 Current address and address for correspondences: Horn PointEnvironmental Laboratories, University of Maryland, PO Box 775,Cambridge, Maryland 21613, U.S.A. (Received October 29, 1990; Accepted May 31, 1991) 相似文献
19.
The effects of light on denitrifying activity during growthwere studied in an aerobic photosynthetic bacterium, Roseobacterdenitrificans (formerly Erythrobacter sp. OCh 114). When aerobicallygrown cells were transferred to anaerobic conditions in thepresence of nitrate, this bacterium exhibited denitrifying activity,with either succinate or malate serving as an electron donorin addition to endogenous substrates. The final product of denitrificationwas identified as nitrous oxide (N2O), a result that confirmsthe presence of nitrate and nitrite reductases, but not N2Oreductase, in these cells. Illumination during aerobic growthcaused a marked enhancement of the denitrifying activity. Theactivity increased with increasing intensity of light up to40 mW cm2 and was over 20 times that in dark-grown cells.Enhancement of denitrifying activity in illuminated cells wasclosely related to increases in levels of components that areinvolved in the denitrifying pathway, namely, nitrate and nitritereductases. Development of a denitrifying system under aerobicconditions and the enhancement of denitrifying ability by lightin Roseobacter denitrificans are unique characteristics, unlikethose of other known denitrifying bacteria. (Received October 29, 1990; Accepted January 17, 1991) 相似文献
20.
Permeability coefficients (PS values) for CO2 of the plasmamembrane (PM) of the unicellular green algae Eremosphaera viridis,Dunaliella parva, and Dunaliella acidophila, and of mesophyllprotoplasts isolated from Valerianella locusta were determinedfrom 14CO2 uptake experiments using the rapid separation ofcells by the silicone oil layer centrifugation technique. Theexperimental PS values were compared with calculated numbersobtained by interpolation of Collander plots, which are basedon lipid solubility and molecular size, for D. parva cells,mesophyll protoplasts isolated from Spinacia oleracea, mesophyllcells and guard cells of Valerianella, and guard cell protoplastsisolated from Vicia faba. The conductivity of algal plasma membranes for CO2 varies between0.1 and 9 ? 106 m s1, whereas for the plasmalemmaof cells and protoplasts isolated from leaves of higher plantsvalues between 0.3 and 11 ? 106 m s1 were measured.By assuming that these measurements are representative for plantsand algae in general, it is concluded that the CO2 conductivityof algal PM is of the same order of magnitude as that of thehigher plant cell PM. Ps values of plasma membranes for CO2are lower than those for SO2, but are in the same order of magnitudeas those measured for H2O. On the basis of these results itis concluded that theoretical values of about 3000 ? 106m s1 believed to be representative for higher plant cells(Nobel, 1983) and which are frequently used for computer-basedmodels of photosynthesis, lack experimental confirmation andrepresent considerable overestimations. However, with severalsystems, including higher plant cells, the conductance of thePM for CO2 was significantly higher in light than in darkness.This suggests that in light, additional mechanisms for CO2 uptakesuch as facilitated diffusion or active uptake may operate inparallel with diffusional uptake. Key words: Conductivity, CO2, permeability coefficient, photosynthesis, plasmalemma 相似文献