摘要:

Abstract1The effects of maleic hydrazide (MH) and isonicotinyl hydrazide (INH) on the reactions catalyzed by pea cotyledon amine oxidase, carrot root l‐glutamic decarboxylase, and wheat seedling transaminase have been studied.2The activity of amine oxidase is inhibited if it is incubated with MH or INH before the addition of substrate, and it is also dependent on the time of preincubation.3The effect of MH and INH is depressed or prevented by α‐ketoglutarate, pyruvate, pyridoxal phosphate, and pyridoxal but not pyridoxine, reduced glutathione, cysteine, or CuCl2.4MH and INH inhibit the l‐aspartate transamination by wheat mitochondria. They only slightly inhibit the decarboxylation of l‐glutamate by the carrot root enzyme.5The role of MH and INH is discussed as carbonyl reagents in plant metabolism. decarboxylase. Thus, the mechanism by which Mh and INH inhibit action of l‐glutamic decarboxylase is rather complicated and will not be elucidated very soon. The inhibition of aspartate transamination by MH and INH can be interpreted in terms of two processes: the combination of the inhibitors with α‐ketogultarate and pyridoxal phosphate which is a coenzyme of the transaminase. Since transamination is one of the most important reactions in the amino acid metabolism controlling the protein level in living cells, the effect of MH and INH should be noticed as shown above. Kim and Greulach (1963) report that MH and 5‐fluorouracil markedly reduce the content of free amino acids and DNA in Chlorella pyrenoideas; this in interesting in view of the present results concerning the

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1966.tb07015.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY

摘要:

AbstractPhosphorus‐32 was absorbed by the mycelium ofCollybia velutipesand translocated to the pilei of intact sporophores within 1.5 hours. In the stipes upward translocation occurred first in the peripheral hyphac followed by movement of the isotoipe into the central hyphac. After 3.0 hours hyphae in the two regions were about equally labelled with the isotope. Except for very minor differences hyphal was the same in the peripheral and central portions of the stip

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1966.tb07016.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY

摘要:

AbstractCoccolith formation inCoccolithus huxleyiwas investigated in a semiquantitative manner by microscopic enumeration of coccolith‐carrying cells appearing, after varying periods in normal growth medium, following an initial removal of all coccoliths by treatment with a decalcifying medium. Coccoliths were formed both in the light and in the dark, but the rate of coccolith formation was very much greater in the light.Time‐course experiments on the uptake of carbon‐14 in coccoliths demonstrated that after a period in darkness, the cells required half an hour of illumination in order to adjust to the light rate of coccolith formation. Coccoliths were produced at a maximum rate only as long as the illumination lasted, although about one hour in the dark was needed before the transition back to the original dark rate was com

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1966.tb07017.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY

摘要:

AbstractBothChlorella pyrenoidosaandChlorella vulgarisgrow equally well at 20°C aerated with ordinary air or mixtures of air with 5 or 12 per cent CO2(5 klux continuous light). Whereas C. vulgaris relatively rapidly adapts to a higher CO2tension, adaptation takes about 24 hours for C. pyrenoidosa.In Chlorella vulgaris pH in the range 3.6–7.6 has no apparent influence on the rate of photosynthesis in experiments having a duration of two hours. This is true both for algae grown aerated by ordinary air and for algae grown with a mixture of 5 per cent CO2in air. The adaptation time must be short. In Chlorella pyrenoidosa the same is found for algae in ordinary air, whereas an influence of pH is seen in some experiments where the aeration was by 5 per cent CO2in air.As is to be expected, the rate of photosynthesis in C. pyrenoidosa during the first two hours is very much influenced by the concentration of free CO2. The highest rate is found at the CO2concentration at which the algae had been growing previously. The influence on the rate of photosynthesis in C. vulgaris is very much less, although in principle the same.The investigation of the corresponding influence on the rate of respiration is complicated by considerable variation from one series to another. In C. vulgaris this is particularly of importance. In C. pyrenoidosa, the highest rate of respiration is generally found at the CO2‐concentration at which the alga had been growing before the experiment.It seems probable that variations between similar series is due to the fact that the algae were grown in continuous light but with dilution with fresh culture medium when the optical density had reached a certain magnitude. Algae grown in this way are neither synchronized nor non‐synchronized.Our thanks are due to the Danish State Research Foundation for financial s

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1966.tb07018.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY

摘要:

AbstractWoody cuttings ofRibes rubrum, an easy plant to root, were extracted with methanol. One fraction of this extract was both water and ether soluble; a part of it was only water soluble. From the water and ether soluble fraction a crystalline compound was isolated which was fully identified withp‐hydroxybenzoic acid (PHB) by m.p., mixed m.p., infrared spectrum, ultraviolet absorption in neutral and alkaline methanol and chemical analyses.For Avena coleoptiles straight growth test,p‐hydroxyhenzoic acid was found to have a significant growth promoting activity in the range 20–100 μg/ml. and it showed strong growth inhibition at concentrations higher than 200 μg/ml.From the same extract fraction a phenolic ester was isolated by paper chromatography which showed a weak growth inhibiting activity. This compound was identified as an ester ofp‐hydroxybenzoic acid by micro‐scale reactions.From the extract soluble only in water further amounts of crystallinep‐hydroxybenzoic acid were obtained by alkaline hydrolysis. This PHB may have arisen from the breakdown of pelargonid

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1966.tb07019.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY

摘要:

AbstractThe response of stomata to varying soil moisture content was studied in cotton by means of a new type of porometer suitable for field work. The results showed that maximum stomatal aperture was only attained when soil moisture was near the upper limit of the so called “available range”. These results indicate the possibility of making practical use of the new type of porometer for the purpose of determining soil moisture deficiency under field conditions, thus aiding in irrigation practi

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1966.tb07020.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY

摘要:

AbstractUnifoliate leaves were individually enclosed in clear, plastic chambers for the 24 hour treatment periods and then sacrificed for Ca analysis. Two transpiration rates were obtained by passing dry air through the chambers tising flow rates of 160 and 260 cm3/min. A third rate was obtained by a combination of shade and the lower air flow rate.Neither the transpiration rate nor solution‐Ca concentration (0.5mMand 2.5 mMof 0.1, and 0.5 strength Hoagland solution) altered the amount of Ca deposited in the unifoliate leaves of 22 day old bean plants (Phaseolus vulgaris). The transpiration rate per unit area of leaf remained constant for all ages studied (1l–20 days) and was 1.8, 2.7, 3.6 g H2O per dm2day for the three different imposed conditions.A definite pattern of Ca deposition occurred. With all the transpiration rates there was a maximum rate of calcium deposition at 13 days of growth and a gradual decrease thereafter. When the Ca concentration of the nutrient solution was 20 μg/ml the daily Ca deposition in terms of water transpired by the unifoliate leaves exceeded this amount, except for the oldest leaf tested, and, the maximum Ca to water ratios were 250, 320, and 430 (μg Ca/g) in order of decreasing transpiration rates.The uptake of Ca against a concentration gradient and approximately the same total uptake regardless of transpiration rates and solution concentrations used, firmly suggest that Ca secretion into root‐xylem elements from a surrounding low level Ca solution requires energy expenditure by the plant.A possible explanation was proposed for the decreased rate of Ca deposition by the unifoliate leaves subsequent to the 1

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1966.tb07021.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY

摘要:

AbstractThe effects of different calcium levels upon germination and tube growth of the pollen ofSetaria sphacelata(Schum.) Stapf and Hubbard were studied at low, optimal and high levels of boron. Calcium (10 and 100 mg/1) stimulated germination at all levels of boron and enhanced tube growth to an even greater degree. The inhibitory effects of high boron levels (50 mg/1) were largely overcome by addition of 10 to 100 mg/1 calcium. Magnesium (1 and 10 mg/1) stimulated germination and tube growth at optimal and high boron levels, but 100 mg/1 magnesium were highly inhibitory. Potassium and sodium had little effect upon pollen germination or tube growth at any level of boron supply. It was concluded that calcium, together with sucrose and borate, might be required for optimal germination and growth of the pollen tubes. Nevertheless, the tubes obtained were much shorter than required for fertilisationin vivo, indicating either that some essential factor was still missing or that the pollen is inherently incapable of producing tubes of adequate length.I wish to thank dr. Donald T. Krizek for critically reading the manuscript.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1966.tb07022.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY

摘要:

AbstractIndoleacetic acid in physiological concentrations was shown to enhance the synthesis of citiate by purified citrate condensing enzyme from castor beans and pig heart. Michaelis constants reveal that with indoleacetic acid in the reaction mixture a higher concentration of acetyl‐CoA was necessary to give maximal velocity. V values with indoleacetic acid in the reaction (physiological concentrations) exceeded V without indoleacetic acid in reaction. Citric acid synthesized from14C acetyl CoA was highly radioactive when indoleacetie acid was present in the reaction, indicating that indoleacetic acid did in fact enhance the synthesis. The data were discussed from the point of view that these studies may provide the basis for studies directed at ultimate understanding of the mechanism of action of indoleacetic aci

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1966.tb07023.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY

摘要:

AbstractAn attempt was made to isolate from potato tuber mitochondria the reported calcium‐45 complex. Mitochondria fractionation results showed that the lipids were not involved in the calcium‐45 complex formation. Using hot water as an extracting solvent it was found that two calcium‐45 complexes occurred in the mitochondria fraction. One of the complexes was readily removable while the other complex was much less readily extractable with hot water. The readily removable calcinm‐45 complex was identified as calcium phosphate and the less readily extractable complex seemed to be directly related to mitochondrial RNA liberation, however, it was impossible to isolate a calcium‐45 ribonucleic acid complex. The extraction of the slowly removable calcium‐45 complex was not a simple liberation of the complex but rather a breakdown which was irreversible and could be inhibited partially by sodium arsenate.A possible explanation of these data is that the TCA soluble fraction represents the total calcium45 uptake by the mitochondria, that is, the calcium‐45 that has been accumulated plus that which is in the “calcium‐carrier complex”. It is suggested that the easily extractable hot water fraction is the accumulated calicum‐45 while the less readily extractable fraction is the “c

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1966.tb07024.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY