摘要:

The mitochondrial and glyoxysomal citrate synthase (EC 4.1.3.7) from the endosperm of germinating castor beans (Ricinus communisL., type Sanzibaricnsis) were purified to a final specific activity of 76 and 78 U (mg protein)−1, respectively. Both citrate synthases could be bound to ATP‐Sepharose. However, only the mitochondrial enzyme could be eluted by either 100 μMoxaloacetate or 100 μMcoenzyme A (indicative of affinity chromatography), while the glyoxysomal enzyme was only eluted by 0.5MKCI (indicative of ion‐exchange chromatography). Many properties of the two isoenzymes were similar including the pH dependence and temperature dependence of activity, the pH stability, and the inactivation of the enzyme at elevated temperatures. The most pronounced differences between the two citrate synthases were the isolelectric points of pH 5.9 for the mitochondrial and of pH 9.1 for the glyoxysomal enzyme. Both citrate synthases are dimers in the native form with a molecular weight of 95000 each, as determined by gel filtration on Sepharose CL‐6B and by polyacrylamide gel electrophoresis in the presence of 0.1% sodium dodecyl sulfate. However, the glyoxysomal citrate synthase existed also as a tetramer with a molecular weight of 200000 in the presence of 1

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1984.tb04240.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

The time course of total citrate synthase activity in castor bean (Ricinus communisL., type Sanzibariensis) endosperm showed a 7‐fold increase during the initial 5 days of germination and a decrease thereafter. All citrate synthase activity in the ungerminated seeds was due to the mitochondrial isoenzyme. After two days of germination the glyoxysomal isoenzyme began to appear. After 5 days the glyoxysomal citrate synthase represented 50 to 55% of the total activity and the mitochondrial enzyme the remainder. This was estimated from (a) inactivation of the glyoxysomal citrate synthase by 5,5′‐dithiobis(2‐nitrobenzoic acid); (b) solid phase adsorption of the glyoxysomal synthase by a specific antiserum; (c) separation of isoenzymes by (NH4)2SO4gradient solubilization.The increase of both citrate synthases during the initial 4 days of germination could be prevented by 10 μg cycloheximide ml−1, but not by 40 or 400 μg chloramphenicol ml−1, indicating a synthesis on 80 S ribosomes. Actinomycin D completely inhibited the appearance of the glyoxysomal enzyme while the mitochondrial enzyme was not affected. Antisera against the two isoenzymes revealed major structural differences between two citrate synthases, however, also some common determinants. No cross‐reaction was observed with the citrate synthase from pig

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1984.tb04241.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Potato plants (Solanum tuberosumL. ev. Ostara) were grown in water culture and the growth rate of individual tubers was measured daily or at two day intervals. Tubers of different growth rate and/or different age (days after tuberization) were harvested and analysed for indolylacetic acid (IAA) and abscisic acid (ABA). Within individual tubers the IAA content decreases from the apical to the basal part of the tuber. Tuber age and corresponding fresh weight are negatively correlated with the endogenous IAA content. If, however, individual tubers of comparable age but different growth rates are compared, a significant positive correlation between growth rate and IAA content is revealed, while ABA showed a significant negative correlation with growth rate. Removal of all fast‐growing tubers from individual plants causes an increase in the growth rate of the remaining tubers within 3–4 days. This coincides with a particularly steep increase in IAA content. The data support the idea that endogenous IAA content may be one factor responsible for controlling the growth rate (“sink‐activity “) of individu

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1984.tb04242.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Intact vacuoles were isolated from leaves of the CAM plant,Kalanchoë daigremontianaHamet et Perr. Both ATPase and acid phosphatase activities were found in the vacuoles. Purified tonoplast vesicles showed only ATPase activity with a pH optimum of 8.0. This activity was Mg2+‐dependent and KCI or NaCI caused a further stimulation. N,N′‐dicyclohexylcarbodiimide, diethylstilbestrol and quercetin inhibited the ATPase almost completely at concentrations well below 1 mM.NaVo3, 1‐ethyl‐3(3‐dimethylaminopropyl)carbodiimide, oligomycin and NaN3had little or no effect. Carbonyl cyanidem‐chlorophenylhydrazone stimulated the ATPase about 40% at 5 × 10−4M.The Kmfor ATP was found to be 0.55 mM.These results indicate that the ATPase found in the tonoplast membrane ofKalanchoë daigremontianais qualitatively similar to that of o

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1984.tb04243.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

In anther cultures ofAnemone canadensisL.,Anemone dichotomaL.,Anemone hupehensisLemoine,Clematis viticellaL. andPapaver setigerumDC. a positive relationship between incubation in 2% CO2and the production of microspore‐derived embryos was observed. In anther cultures ofNicotiana tabacumL.,Anemone hupehensisandClematis viticellaa combination of cold treatment (7°C) and incubation in 2% CO2increased embryo production. InAnemone canadensiscold treatment increased the number of proembryos, whereas incubation in 2% CO2had no effect. InAnemone hupehensis5% CO2increased embryo production by more than 2%. InAnemone dichotomaandPapaver setigerum2% CO2was the more efficient level. CO2had no significant effect on pH in the culture medium in anther cultures ofAnemone canadens

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1984.tb04244.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Among 30 plant species examined, the PPi‐phosphofructokinase (EC 2.7.1.90) was found in leaves of 21 plants. Some of the plants exhibit no activity of ATP‐dependent phosphofructokinase but display only activity of PPi‐phosphofructokinase. A partly purified preparation of PPi‐phosphofructokinase with specific activity of 8.4 Hmol (mg protein)−1min−1was obtained fromSanseviera trifasciataleaves. The enzyme is restricted to the cytoplasm, it exhibits pronounced substrate specifity, requires Mg2+ions, is inhibited by AMP, PEP, methylenediphosphonate and stabilized by mercaptoethanol. At pH 7.8 with 1.5 mMMgCl2the following KMvalues were observed: pyrophosphate, 0.58 mM; fructose 6‐phosphate, 0.8 mM. The KMvalues for substrates of reverse reaction (pH 7.3; 2 mMMgCl2) are of the same order of magnitude: 0.83 mMfor fructose 1,6‐diphosphate, and 0.14 mMfor orthophosphate. The molecular weight of the studied enzyme is about 125 000 dalton as estimated by

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1984.tb04245.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

The effect of varying leaf number on response of soybean (Glycine max(L.) Merr. cv. Fiskeby V) to CO2enrichment was studied. Plants were trimmed at pod set to 15 pods and 1 or 3 leaves (15:1 and 5:1 pod/leaf ratio) and placed in 350 or 1000 μl/l CO2growth chambers. Photosynthetic rates and dry weights were measured 6 times in all plants at each CO2concentration over a period of 39 days. Measured at treatment CO2concentration, photosynthetic rates deelined rapidly in enriched plants, but remained higher than those of non‐enriched plants. When all plants were measured at the same CO2concentration, for most sampling dates, neither growth, CO2concentration or pod/leaf ratio significantly affected rates of photosynthesis per unit area of comparable leaves. CO2enrichment significantly increased total weights and pod weights in 15:1 but not 5:1 pod/leaf ratio plants. Plants with a 5:1 pod/leaf ratio had significantly higher total and pod weights than 15:1 ratio plants. Both the photosynthesis and dry weight data suggest that plants in the 5:1 ratio enriched treatment were sink‐limited, but plants in all other treatments were source lim

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1984.tb04246.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Conditions have been established for the rapid flow analysis of leaf protoplasts ofNicotiana tabacumL. cv. Xanthi using a flow cytometer‐cell sorter. A procedure based upon chlorophyll autofluorescence was devised to permit the systematic evaluation of flow conditions in order to identify those under which protoplast damage was minimized. These conditions were employed for the flow sorting of protoplasts, following which it was possible to regenerate the sorted protoplasts into complete plants. The application of flow sorting is discussed for the rapid identification and selection of somatic hybrids produced by protoplast fusio

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1984.tb04247.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Embryonic axes and cotyledons of three soybean (Glycine maxL. cv. Gudzon) seed lots designated as “normal”, “naturally aged” and “acceleratedly aged” were analyzed for their organic free radical contents. No signals of free radicals were found in ESR spectra from cotyledonary material of the three samples investigated. High levels of organic free radicals were observed in the embryonic axes. There were significant differences in the free radical contents of the embryonic axes: the relative values of free radicals were 100, 190 and 170% for samples aged normally, naturally and in an accelerated manner, respectively. These results point to the physiological role of the embryonic axes during natural or accelerated aging of seeds, notwithstanding that the axis is a small part as compared to the cotyledons. It is suggested that lipid peroxidation in embryonic axes may play an important role in the seed deterioration d

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1984.tb04248.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Mesophyll cells of strawberry were isolated mechanically by a hand homogenizer, One g healthy, fully‐expanded leaves yielded 107cells. The agar culture method was the only culture technique found suitable to obtain any quantitative dat

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1984.tb04249.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY