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1.
Rice (Oryza sativa L. cv. Yamabiko) seedlings germinated underwater for 5 days contained small amounts of heme a and protohemebut no protochlorophyll(ide) [Pchl(ide)]. Levels of hemes andPchl(ide) increased rapidly upon transfer to air. When expressedin terms of fresh weight of tissue, hemes reached the levelsin aerobic controls after 24 h of contact with air, but Pchl(ide)did not. A comparison of the increases during 24-h adaptationto air in levels of heme a and Pchl(ide), which are specificto mitochondria and plastids, respectively, suggested that thedevelopment of mitochondria preceded that of plastids. The rateof synthesis of 5-aminolevulinic acid (ALA) was low in submergedseedlings, as compared to the rate in aerobic controls, butit increased during air adaptation. The sum of the amounts ofheme a, protoheme and Pchl(ide) increased in parallel with theamount of porphyrins, equivalent to the amount of ALA synthesizedduring the experimental period. When submerged seedlings thathad been pretreated with levulinic acid were exposed to air,no Pchl(ide) was formed. In contrast, Pchl(ide) accumulatedunder water when submerged seedlings were fed with ALA. Theseresults indicate that the synthesis of ALA, the limiting stepin the synthesis of Pchl(ide), is repressed under hypoxic conditions. 1 Present address: KRI International, Inc., Kyoto Research Park17, Chudoji Minami-machi, Shimogyo-ku, Kyoto, 600 Japan. 2 Present address: Research Institute for Bioresources, OkayamaUniversity, Kurashiki, 710 Japan.  相似文献   

2.
Changes in activities of enzymes and levels of antioxidant substratesinvolved in the -detoxification system in seedlings of rice (Oryza sativa L. cv. Yamabiko) inresponse to variations in the oxygen environment were studied.Activities of superoxide dismutase, ascorbate peroxidase, monodehydroascorbatereductase, dehydroascorbate reductase, glutathione reductaseand catalase, expressed either on the basis of fresh weightof shoots or relative to levels of soluble protein were muchlower in seedlings germinated under water for 6 days than inthose germinated in air for the same period of time. When submergedseedlings were exposed to air, the activities of these six enzymesincreased to or exceeded the levels in aerobically grown controlsduring 24 h of adaptation to air. Ascorbate and glutathione,which act as antioxidant substrates in the -detoxification system, were present in submergedseedlings at nearly the same levels as those found in aerobicallygrown controls. On exposure of submerged seedlings to air, thelevel of ascorbate in creased slightly, but the level of glutathioneshowed a rapid increase, reaching 7 times that in aerobicallygrown controls within 12 h of adaptation to air. Levels of allsix antioxidative enzymes and of two substrates involved inthe detoxification of the superoxide radical increased withincreases in oxygen tension in the environment. Moreover, thedevelopment of this system consisted of two steps, namely, arapid increase in the level of glutathione and a subsequentslow increase in the activities of antioxidative enzymes. 1 Present address: Research Institute for Bioresources, OkayamaUniversity, Kurashiki, 710 Japan.  相似文献   

3.
Shibasaka M  Tsuji H 《Plant physiology》1988,86(4):1008-1012
Respiratory activities were compared among rice seedlings germinated in air for 6 days (aerobic seedlings), those germinated under water for 5 days (submerged seedlings), and those grown in air for 1 day after 5 days' submerged germination (air-adapted seedlings). The respiratory activity of the submerged seedlings increased rapidly on transfer to air and reached a plateau at 16 hours in air. Respiration of the submerged seedlings was as sensitive to cyanide as those of aerobic and air-adapted seedlings. 2,4-Dinitrophenol had no effect on the respiration of the submerged seedlings, but stimulated those of the other two types of seedlings. Mitochondria from three types of seedlings did not differ in the ADP/O ratio and the respiratory control ratio (RCR) when succinate was oxidized. However, mitochondria from submerged seedlings (submerged mitochondria) showed poor RCR of about unity when malate was oxidized. Both the rate of succinate oxidation and succinate dehydrogenase activity were low in submerged mitochondria, but increased during air adaptation. Although submerged mitochondria oxidized malate very slowly, this activity increased after exposure to air without any increase in malate dehydrogenase activity. When NAD+ was added to submerged mitochondria, oxidation of malate was restored to the level of the aerobic controls. Addition of NAD+ enhanced the state 3 rate in submerged mitochondria, and RCR recovered to nearly the same value as that of the aerobic controls. Similar effects of NAD+ on 2-oxoglutarate oxidation were observed. All these defects in submerged mitochondria were repaired during air adaptation. These results suggest that NAD+-linked substrate oxidation was low in submerged mitochondria because of NAD+ deficiency, and that the oxidation increased with an increasing level of NAD+ during air adaptation.  相似文献   

4.
Changes in activities and levels of superoxide dismutase (SOD, EC 1.15.1.1) isoenzymes were studied during air adaptation of submerged rice (Oryza sativa L.) seedlings. Seeds were germinated for 6 d in the dark under water (submerged), and then for another day in air (air-adapted). For a control, seeds were germinated for 6 d throughout in air (aerobic). Staining for activity of SOD of shoot extracts showed a total of five major distinct forms of SOD: one mitochondrial Mn enzyme (mtSOD) and four CuZn enzymes, one of which was plastidic (plSOD) and the other three cytosolic (cytSOD). Activity of plSOD was much lower in submerged seedlings than in aerobic controls and increased after exposure to air. In contrast, mtSOD activity in submerged seedlings was as high as that found in aerobic controls, and did not increase upon exposure to air. One of the cytSODs showed responses similar to those of plSOD. The activities of another two cytSODs were slightly lower in submerged seedlings than those in aerobic controls, but decreased after 24 h of air adaptation. Western blot analysis revealed that these changes in activities of SODs are due to changes in the levels of their enzyme proteins. We also followed changes in the levels of cytochrome c and ferredoxin-NADP+ reductase (EC 1.6.99.4) as indices of the development of mitochondria and plastids, respectively. Organelle SODs were always present at higher levels than would be expected in view of the development of the electron-transport systems of the corresponding organelles during submergence and the subsequent air-adaptation period.Abbreviations cytSOD cytosolic CuZn-superoxide dismutase - FNR ferredoxin-NADP+ reductase - mtSOD mitochondrial Mn-superoxide dismutase - plSOD plastidic CuZn-superoxide dismutase - SOD superoxide dismutase We gratefully acknowledge Dr. A. Wada, Kyoto University, for the use of a densitometer for this work, and also would like to thank Y. Maki, Kyoto University, for help with the densitometry of the photographs.  相似文献   

5.
Indoleacetate oxidase activity in Pharbitis nil, Japanese morningglory, was zymographically examined. Some isozymes appearedonly after treatment with a low concentration of hydrogen peroxide.This phenomenon was assumed to be due to the overlapping ofboth isozymes and natural inhibitor substances on the zymograms. 1Present address: Biological Institute, Department of LiberalArts, Shizuoka University, Ooya 836, Shizuoka, Japan. (Received September 30, 1968; )  相似文献   

6.
Rice seeds were germinated for up to 5 days under water (submerged)and some for another day in air (air-adapted). Control seedswere germinated for 6 days throughout in air. Low-temperaturedifference spectra of shoot mitochondria were compared amongthese three types of seedlings. All cytochromes found in theaerobic seedlings were present in the submerged seedlings. However,there were some differences in the cytochromes b553 and c ofthese two types of seedlings. The cytochrome aa3 peak heightand cytochrome oxidase activity per mitochondrial protein increased1.6- and 2.8-fold, respectively, during air adaptation. Slightlyhigher concentrations of the b-type cytochromes than found inair-adapted mitochondria were already present in submerged mitochondria.The computed difference between the dithionite-reduced differencespectra of mitochondria from submerged seedlings before andafter air adaptation, showed that cytochromes aa3 and c hadincreased more than cytochrome b557 during air adaptation. (Received November 16, 1987; Accepted March 16, 1988)  相似文献   

7.
Pure microbody fractions could be prepared in considerable yieldsfrom sweet potato root tissue slices incubated for 16 hr and3 days. The ratio of catalase activity to phospholipid contentin the fraction from slices incubated for 3 days was about 3times that from slices incubated for 16 hr. Total catalase activityin the former slices was about twice that in the latter. Thissuggests that catalase synthesized during incubation of theslices is transported into microbodies preexisting in intacttissue. 1 Present address: Laboratory of Food Technology, Faculty ofApplied Biological Science, Hiroshima University, Fukuyama,Hiroshima 720, Japan. 2 Present address: Terumo Co., Ltd., Omiya, Fujinomiya, Shizuoka418, Japan. (Received July 1, 1982; Accepted September 24, 1982)  相似文献   

8.
Catalase activity increases when slices of sweet potato roottissue are incubated in air. The increase is due to de novosynthesis of the enzyme protein and probably also to activationof a precursor protein [Esaka et al. (1983) Plant & CellPhysiol. 24: 615]. The activity-increase was partly depressedwhen tissue slices were incubated in ethylenecontaining air,while the immunologically determined amount of catalase proteindid not increase, rather it decreased, under the same conditions.We propose that ethylene inhibits the de novo synthesis of catalaseprotein but not the activation of precursor protein. Catalasefrom tissue slices incubated in ethylene-containing air migratedfaster on a polyacrylamide gel than that from intact tissueor tissue slices incubated in air. When either polyacrylamideor an SDS-polyacrylamide gel applied with crude extract fromtissue slices incubated in ethylene-containing air underwentimmunological blotting, the blots were much fainter than thosefor intact tissue. In addition, microbody membrane fractionfrom incubated tissue slices contained a significant amountof catalase which was sedimented at the bottom of a sucrosedensity gradient (20–70%) and was not solubilized by highconcentrations of lubrol PX. The fraction showed an exceptionallyhigh catalase activity per unit amount of immunoreactive proteinto anti-catalase antibody. We propose that ethylene causes somemodification of catalase protein which facilitates the formationof aggregates or cores. 1Present address: Laboratory of Food Technology, Faculty ofApplied Biological Science, Hiroshima University, Fukuyama,Hiroshima 720, Japan. 2Present address: Terumo Co. Ltd., Omiya, Fujinomiya, Shizuoka418, Japan. (Received October 16, 1982; Accepted February 24, 1983)  相似文献   

9.
A proteinaceous factor required for the Pi-dependent reactivationof the inactive form of pyruvate Pi dikinase from dark-treatedmaize leaves, was isolated and partially purified by SephadexG-200 gel filtration. The factor, which is sensitive to trypticdigestion and heat-treatment, showed enzyme-like kinetic behaviourin the activation reaction. 1Present address: Laboratory of Biochemistry, Department ofAgricultural Chemistry, School of Agriculture, Shizuoka University,836 Ohya, Shizuoka 420, Japan. (Received February 25, 1974; )  相似文献   

10.
Nitrate reductase activity in rice seedlings showed daily fluctuations.Seedlings placed in the dark slowly lost activity and quicklyregained it when exposed to sunlight. Etiolated seedlings alsoshowed rapid increases in activity when transferred to sunlight.This increase in activity by sunlight was inhibited by bothchloramphenicol and ethionine. Ethionine inhibition was reversedby methionine. Purification of nitrate reductase was carriedout by ammonium sulfate fractionation and DEAE-cellulose columnchromatography. Nitrate reductase was purified about 40-foldfrom plants placed in the dark and in sunlight. Incorporationof mediionine-S-14CH3 into the nitrate reductase fraction wasstudied. In sunlight, the specific radioactivity of the nitratereductase fraction from the DEAE-cellulose column increased2-fold as compared with that of the crude extracts. Specificradioactivity did not increase in the dark. 1Present address: Asahi Kasei Chemicals Industry Co., Ltd.,Sameshima 2-1, Fuji, Shizuoka, Japan (Received December 3, 1968; )  相似文献   

11.
Lipoxidase activity in etiolated wheat seedlings grown for 3.5days was localized primarily in the coleoptile and first leafof the seedling with moderate activity in the germinated seedand root. After 7 days growth, the distribution of lipoxidasewithin the plant did not change markedly while the total activitydecreased. The dormant wheat seed exhibited 2 major and 2 minor bands oflipoxidase activity on polyacrylamide gel zymograms. After germination,there was a marked change in the relative intensities of the4 lipoxidase bands depending on the part of the seedling assayed. 1 Supported in part by funds from the Agricultural ResearchService, U. S. Department of Agriculture Grant No. 12-14-100-7654(74)administered by the Western Utilization Research and DevelopmentDivision, Albany, California. Published with the approval ofthe Director of the Wisconsin Agricultural Experiment Station. 2 Present address: U. S. Department of Agriculture, NorthernGrain Insects Research Laboratory, Brookings, South Dakota 57006,U.S.A. 3 Present address: Institute of Experimental Phytopathologyand Entomology, Ivanka Pri Dunaji, Czechoslovakia.  相似文献   

12.
Lemna paucicostata 6746, a short-day plant, flowers in agedHutner's medium even under continuous light, when the endogenousnitrogen level decreases to below 1.6 µmg fr wt. At thesenitrogen levels, daylength-independent flowering of the plantcan be induced even in fresh Hutner's medium. Thus, old-cultureflowering in Hutner's medium is due to nitrogen deficiency inthe plants. 1Present address: Biological Institute, Faculty of Science,Shizuoka University, Shizuoka 422, Japan. (Received February 12, 1987; Accepted August 28, 1987)  相似文献   

13.
TA [4-ethoxy-1-(p-tolyl)-s-triazine-2,6 (1H, 3H)-dione] wasprepared chemically by intramolecular cyclization of IU [2-ethyl-3-methoxycarbonyl-1-(p-tolylcarbamoyl)-isourea],which has been reported to be an effective GA-synergist. TAalone slightly stimulated the shoot growth of rice seedlings,and in combination with GA showed a distinctly synergistic effecton the growth of rice shoots. The results suggest that TA andIU are nearly equal in their physiological activity. From theresults of the rice seedling test of these two compounds andtheir analogs, structure-activity relationships of isoureaswere correlated with those of triazinones. The results of applicationof IU, at 100 mg/liter to rice seedlings followed by extractionand silica gel thin-layer chromatography, suggested that IUwas biologically converted into its closed-ring form, TA, whichis a stable and potent GA-synergist. Thus, isoureas like IUseem to be easily converted into their counterparts, triazinones,in rice tissues. 1 This paper is Part III in the series "Plant growth-regulatingactivities of isourea derivatives and related compounds." 2 Permanent address: Agricultural Chemicals Research Laboratories,Sankyo Co., Ltd., Hiro-machi, Shinagawa-ku, Tokyo 140, Japan. 3 Present address: Higashi-Osaka Junior College, Nishitsutsumigakuen,Higashi-Osaka 577, Japan. (Received February 21, 1977; )  相似文献   

14.
S-Adenosyl-L-methionine-magnesium-protoporphyrin IX methyltransferase(EC 2.1.1.11 [EC] ) is present in greening barley seedlings associatedwith the particulate fraction. This enzyme was purified 20 foldusing protamine and ammonium sulfate precipitation. The enzymewas active over a wide pH range with highest activity at pH7.5. The Km values for Mg-protoporphyrin IX and S-adenosylmethioninewere 48 and 39 µM, respectively; S-adenosylethionine andS-adenosyihomocysteine were competitive inhibitors with respectto S-adenosylmethionine; hemin inhibition was non-competitivewith respect to Mg-protoporphyrin IX; thiol compounds exhibiteda stimulatory effect on enzyme activity. The properties of theenzyme are discussed and compared with the enzyme from otherorganisms. 1 This research was supported in part by the Utah State AgriculturalExperiment Station. 2 Present address: Department of Chemistry, Boston University,Boston, Massachusetts, U. S. A. 3 Present address: Department of Biochemistry and Microbiology,Faculty of Pharmacy, Comenius University, Bratislava, Czechoslovakia. (Received February 20, 1978; )  相似文献   

15.
Salt stress-induced changes of intracellular pH and in levelsof phosphorous compounds were monitored in intact root tipsof barley seedlings (Hordeum vulgare cv. Akashin-riki) by invivo 31P-nuclear magnetic resonance (NMR) spectroscopy. Vacuolaralkalization was observed after treatment with both 300 and500 mM NaCl. Much of the observed apparent alkalization of thecytoplasm was eliminated when the effect of Na+ ions on thetitration curve was considered. Within 1 h after the initiationof salt stress, levels of glucose-6-phosphate and UDP-glucosedecreased markedly, and such decreases might lead directly orindirectly to cell death. Simultaneous measurements of the externaland intracellular pH revealed the promotion of external acidificationand internal alkalization during salt stress. Possible mechanismsof Na+/H+ antiport at the tonoplast and the role of proton-pumpin the plasma membrane are discussed. 3Present address: Shijonawate Gakuen Women's Junior College,Daito, Osaka, 574 Japan.  相似文献   

16.
Methenyltetrahydrofolate cyclohydrolase (E.C. 3.5.4.9 [EC] ), whichis responsible for the enzymatic conversion of 5,10-methenyl-H4FAto 10-formyl-H4FA, has been found in various plant tissues.The enzyme was partially purified from pea seedlings and someof its properties were investigated. It was unstable, but wasstabilized by the addition of 25% glycerol. The enzyme was purifiedabout 60-fold by fractionation with ammonium sulfate and columnchromatography on DEAE-cellulose in the presence of 25% glycerol.Optimum pH for the reaction was 7.7. Michaelis constants for5,10-methenyl-H4FA in the forward reaction, and for 10-formyl-H4FAin the reverse reaction were 4x10–5M and 2x10–4M,respectively. The apparent equilibrium constant for the reactionwas calculated as 50. Enzyme activity was greatly inhibitedby the reduced forms of folate derivatives. The probable participationof this enzyme in the regulation of folate coenzyme levels inplant tissues has been suggested. 1 Studies on the enzymatic synthesis and metabolism of folatecoenzymes in plants, VI. (For Part V, see Reference (5) ). Partof this paper was presented at the 22nd annual meeting of theJapan Vitamin Society held at Hiroshima on October 14, 1970. 2 Present address: Sizuoka Eiwa Junior College, Ikeda, Shizuoka. (Received September 9, 1972; )  相似文献   

17.
The relation between dark anaerobic hydrogen (H2) evolutionof marine unicellular green algae and the energetic state ofthe cells, as revealed by adenine nucleotide (AN) levels, wasstudied. One of the 4 investigated strains produced H2 continuouslyfor 48 h and maintained its adenylate energy charge (EC) atabout 0.6, whereas the H2 evolution of the other strains stoppedwithin 24 h and their EC decreased to low values. Prolongedaerobic preincubation resulted in reduced H2 evolution and astronger decrease in EC during subsequent anaerobiosis. Amongcultures of the same strain, H2 evolution was correlated withthe initial pool levels of total AN and chlorophyll and withthe ATP level and EC during anaerobiosis. These results indicatea dependence between H2 evolution and capacity for starvation.EC was not affected by complete inhibition of H2 evolution bycarbon monoxide in one strain but was significantly loweredin another strain. This difference between the two strains isinterpreted as reflecting a different dependence on, or utilizationof, alternative pathways for disposal of electrons during fermentation,although H2 evolution apparently played a minor and non-essentialrole in the dark anaerobic fermentation. 1 Present address: Institute of Oceanic Research and Development,Tokai University, Orido, Shimizu, Shizuoka 424, Japan. 2 Present address: Institute of Marine Research, Directorateof Fisheries, P.O. Box 1870, N-5011 Bergen-Nordnes, Norway. (Received November 19, 1986; Accepted March 17, 1987)  相似文献   

18.
Electron microscopic observations revealed that electron-denseantimonate Ca2+ deposits were mostly localized in the vacuoleand the intercellular space in both maize and winter wheat whentheir seedlings were grown at 25°C. The reaction products—ceriumphosphate deposits of Ca2+- ATPase activity were mainly seenat the cytoplasmic side of the plasma membrane. Few cerium phosphatedeposits also were observed on the nuclear envelope. In bothspecies, after 1 or 3 h 2°C chilling, antimonate Ca2+ depositsincreased in the cytosol and the nucleus, but cerium phosphatedeposits showed no visible difference compared to their corresponding25°C seedlings. After 12, 24, or 72 h chilling, maize seedlingsstill maintained a high level of antimonate Ca2+ deposits inthe cytosol and the nucleus. During these periods, maize Ca2+-ATPase,as indicated by the number of cerium phosphate deposits, becameless and less active as chilling proceeded. In winter wheat,the increased cytosolic and nuclear antimonate Ca2+ depositswere restored to a low resting level after 12, 24, or 72 h chilling,while the Ca2+-ATPase was maintained active, contrary to maizescenario. The transient cytosolic and nuclear Ca2+ increaseand the activities of Ca2+-ATPase during chilling are discussedin relation to plant chilling injury and cold acclimation. 3 Present address: Department of Agricultural, Food and NutritionalScience, University of Alberta, Edmonton, Canada T6G 2P5.  相似文献   

19.
Significant leaf sheath elongation occurred within 24 hr afterapplication of 10 µg (0.67, µCi) of ent-(3H)-17-kaurenoicacid (KA) to individual seedlings of dwarf rice cv. Tan-ginbozu,but this growth was unaccompanied by production of significantlevels of radioactivity in more polar, acidic, ethyl acetate-solublemetabolites of (3H)-KA. However modest levels of radioactivityappeared in the highly water-soluble fraction by hour 24, subsequentto the most rapid phase of KA-induced growth. Growth continuedand by hour 48 was accompanied by the appearance of small amountsof radioactivity in polar, acidic products. It would appearthat KA per se, and not its metabolic products, may be responsiblefor the leaf sheath elongation noted at hour 24. On the speculation that it might be a metabolite of KA, gibberellinA14 (GA14) was applied simultaneously with (3H)-KA to individualrice seedlings. Several changes in the metabolism of 3H-KA inthe presence of GA14 were noted, and GA14 antagonized the KA-inducedsheath elongation. 1Present address: Botany Department, Rhodes University, Grahamstown,6140, South Africa. 2Present address: Crop Science Department, University of Saskatchewan,Saskatoon, Sask. S7N OWO, Canada. (Received May 12, 1975; )  相似文献   

20.
Tea seedlings were treated with 14C-methylamine to cause synthesisof 14C--glutamylmethylamide (N-methyl-14C). The metabolic conversionof -glutamylmethylamide was studied by tracing 14C. 14C--Glutamylmethylamide (N-methyl-14C) translocated from rootsand cotyledons to shoots of tea seedlings, was converted almostentirely into caffeine. Conversion was greater in light-exposedsamples. For those grown in the dark, the converted amount didnot correspond to the total caffeine produced. More 14C--glutamylmethylamidewas present in stems than in leaves, but with 14C-caffeine,the opposite was found. When 14C--glutamylmethylamide or 14C-methylamine was appliedto leaf disks, 14C-caffeine was biosynthesized from both substances. 1 Present address: Department of Agricultural Chemistry, ShizuokaUniversity, Iwata, Shizuoka 438, Japan. (Received September 25, 1971; )  相似文献   

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