bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Preparation Method on the Induction of (Sodium + Potassium) –Activated Adenosine Triphosphalase from Sugar Beet Root and its Lipid Composition
Authors: HANSSON G. , KUIPER P. J. C. , KYLIN A.
Published: April 2006

The (Na++K+)–stimulation of the ATPase activity in a paniculate fraction from sugar beet roots was compared after inducing treatments with dithiothreitol (DTT), cystein or deoxycholate (DOC). Protection of SH groups by cystein or DTT increased the specific activity at the optimal Na: K ratio (25 :25 mM) with a factor of about 5 as compared to the untreated fraction, and with a factor of about 3 as compared to particles treated with DOC. DTT acted chiefly at the optimum ratio of Na : K (25 :25 mM), whereas a less specific stimulation at any proportion of the couple Na : K was observed after treatment with DOC or cystein. A combined treatment (DOC + DTT) led to inactivation of the DTT effect.

Treatment with DTT resulted in a loss of lipids, which were replaced by water, but otherwise little swelling took place. The loss of lipids was almost exclusively due to loss of phospholipids, and among these the zwitterkonic phos–phatidyl choline and phosphatidyl ethanolamine were affected more than the acidic phosphatidyl glycerol or phosphatidyl inositol. The sulfolipid was maintained within the particles. The combined treatment “with (DOC + DTT) led to further losses of lipid material at the same time as strong swelling took place. As compared to the treatment with DTT alone, the additional loss of lipids occurred mainly from the (sterol glycoside + cerebroside + digalactosyl diglyceride –fraction) and from the solfolipid, with some losses also from the (pigments + neutral), phosphatidyl choline and phosphatidyl glycerol fractions.

The results are in agreement with our earlier data, which also show that lipid fractionation is important for the revealing of (Na+ 4– K+)–stimulated ATPase activity, possibly because of the negative electric charge of the sulfolipid, which is characteristic for the induced preparations and which may be connected with the specific site of stimulation by the cations.
The Effect of Magnesium and Calcium Ions on Adenosine Triphosphatases from Wheat and Oat Roots at Different pH
Authors: KYLIN A. , KÄHR M.
Published: April 2006

Microsomal fractions from wheat (Triticum vulgare) and oat (Avena sativa) roots were used to study Mg2+ and Ca2+ activated adenosine triphosphatases, their dependence of pH, and how Mg2+ and Ca2+ compete or add in stimulation and inhibition.

Wheat gives a high proportion of Ca2+ stimulated ATPase. Less effect is obtained with Mg2+. The characteristics of oar ATPase are the reverse.

The ATPase from the wheat roots depends on the mineral nutrition. A kinetïc analysis shows one site, where Mg2+ and Ca2+ at low concentrations (or complexes between the di‐valents and ATP) cooperate in the activation of the ATPase. The action of this site is more dearly expressed at pH 6.0 than at 6.8, and more clearly in the preparations from low salt roots than in those from high salt conditions. In another site, which is particularly evident in preparations from high salt roots tested at pH 6.8, high concentrations of Mg2+ inhibit the ATPase; this inhibition is competitively relieved by Ca2+. The specific activity of the ATPase from high salt roots of wheat is higher than that from low salt roots, although the amount of protein of the fraction studied remains the same, when calculated per g fresh weight of the roots.
Occurrence of Inverted Water Potential Gradients between Soil and Bean Roots
Authors: TAERUM RAGNAR
Published: April 2006

Measurements with a pressure chamber were made of the xylem water potential of leaves, shoots and roots from bean plants (Pkaseolus vulgaris L. cv. Processor) grown with a 12 hour dark period and natural or artificial light conditions during the day. The water potentials were measured at the end of a dark period and during the light period.

Measurements taken at the end of the dark period indicated normal potential gradients within the soil/plant system (leaf < shoot < root < soil), when the matric potential of soil water was relatively high (above −0.02 bar), and the gradients then also remained normal during the day (natural light). When the soil water potential was −1 bar or lower in the morning, however, the root xylem water potential was higher than the soil water potential; at very low soil water potentials (< −4 bar) it remained higher during most of the day. In this case also leaf and shoot xylem water potentials were higher than the soil water potential in the early morning, although decreasing rapidly in daylight.

Under artificial light, both leaf and root water potentials were higher than the soil water potential throughout the whole diurnal cycle when the latter potential was below −4 bar.

From measurements of stomatal diffusion resistance, transpiration, relative water content of leaves and of changes in the matric potential of soil water, it was concluded that when the matric potential of soil water was low, water could be taken up by the plant against a water potential gradient. Because leaf xylem water potential was always lower than root xylem water potential, the mechanism involved in the inversion of water potential gradient must be localized in the roots, and probably related to ion uptake.

Symbols and abbreviations used in the text: Ψ: Plant water potential (thermocouple psychrometer); Ψx: Xylem water potential (pressure chamber); Ψs: Osmotic potential of xylem sap; Ψm: Matric potential of soil water; RWC: Relative water content.
Root Formation in Pea Cuttings
Authors: ERIKSEN E. NYMANN
Published: April 2006

The importance of the active shoot meristems for root formation in cuttings has been investigated through disbudding, decapitation or both disbudding and decapitation of pea cuttings at different time intervals after the removal of the cutting.

Decapitation and disbudding within the first 4 days after cutting drastically reduce both the number of rooted cuttings and the number of roots per cutting. Treatment 5 to 6 days after cutting has little or no effect on the root formation or the number of roots per cutting.

Redaction in rooting is explained by the removal of the production center(s) for the growth promoters which are necessary for root formation. It is deduced from the results obtained that the initiation phase in pea cuttings is about four days.

The author is much indebted to the Department of Plant Physiology of the Royal Veterinary and Agricultural University, Copenhagen, for permission to use its growth chambers during the present investigations.
Triterpeneglycosideg as Inhibitors of Fungal Growth and Metabolism
Authors: OLSEN ROLF A.
Published: April 2006

Ergosterol was found to be the main sterol in the mycelia of Opbiobolus graminis, Neurospora crassa, and Aspsrgillus niger, A correlation was found between the amount of sterols in the mycelia of different fungi and the inhibitory effect of aescin. Aescin treatment caused a reduction of the amount of extractable sterols in the mycelia. The sterols seemed to be located mainly in the plasma membranes, and only trace amounts were Found in the mitochondrial membranes.

The relative amount of sterols in the plasma membrane was found to be higher in O. graminis than in N. crassa and A. niger.

Ca2+ interfered with the interaction, of sterols and aescin. In N. crassa the decreased inhibitory effect of aescin in the presence of Ca2+ was due to the reduced binding of the inhibitor to the sterols in the plasma membrane.
Effects of Kinetin, Gibberellins and (±) Abscisic acid on the Germination of Lettuce (Lactuca sativa)
Authors: REYNOLDS T. , THOMPSON P. A.
Published: April 2006

Germination responses of achenes of lettuce (Lactuca sativa L, cv. Arctic King) to treatment with kinetin, gibbe‐rellins and abscisic acid were examined over a range of temperatures: in both light and dark.

Kinetin (0.1–10 mg/l) strongly promoted germination at temperatures above 27±C in continuous light or after short periods of illumination during the early stages of imbibition. It also relieved the inhibitory affects of abscisic acid in these conditions. In total darkness however kinetin treatment resulted in only a minor promotive effect.

Treatment with gibberellic acid (A3) or a mixture of gibberellins A4 and A7 were much less effective in promoting germination at higher temperatures of lettuce achenes exposed to light but were strongly promotive in the dark.
Slime of Myxococcus virescens
Authors: STAHL STEN
Published: April 2006

The slime excreted by two strains of Myxococcus virescens during growth in liquid casitone medium was studied. Strain S1H, unable to grow in dispersion, excreted slime during growth later than strain D11, which grows in dispersion. Slime was precipitated from the cell‐free culture solution with ethanol and the crude precipitate fractionately dissolved using first pH 5,4 and then pH 9.0 for the remainder of the precipitate. Comparatively more material from strain S1H than from strain D11 belonged to the pH 9.0 fraction. The fractions thus obtained were dialyzed and then lyophilized.

The composition of the slime preparations varied with the density of the harvested cultures. The slime fraction dissolved at low pH contained 12–18 % (w/w) Folin reactive material, 2–4% lipid and 5–30% anthrone positive material (glucose equivalents). The fraction soluble at pH 9.0 was richer in Folin positive material. About 25% of the proteolytic activity in the culture solution was recovered in the slime preparations. No DNA was detected in the slime, unless the cultures were harvested daring the phase of decline.

The high polymers of the slime were separated from material of low molecular weight and coprecipitated media constituents by gel filtration on Sepharose 2B. The relative amount of the high polymers increased during growth, although they seemed to be degraded in the culture during the phase of decline. The polymer had a molecular weight of about 20 million. In most preparations: it was Folin positive.
Permeability of Bacteria to Inorganic Cations. A Comparison between a Psychrophilic Achromobacter Strain and Escherichia coli
Authors: LEDEBO INGRID , LJUNGER CLAES
Published: April 2006

The permeability of a psychrophilic Acbromobacter strain to the chlorides of Na, K, Mg and Ca was investigated with light‐scattering technique. Comparisons, were made with cells of Escherichia coli B. Cells of both strains suspended in “water were plasmolyzed by 0.1 or 0.2 M solutions of MgCl2 or CaCl2 without subsequent deplasmolysis. NaCl or KCl also plasmolyzed the cells, but deplasmolysis followed.” When suspended in growth medium E. coli became completely de‐plasmolyzed., whereas the psychrophile still excluded MgCl2 and CaCl2 to a great extent. The plasmolysis and deplasmolysis were reversible. Electron micrographs of the psychrophile exposed to CaCl2 confirmed the presence of plasrnolysis.
Cyclic Mononucleotide‐Gibberellin Interactions in the Flowering and Proliferation of the Long‐Day Plant Lemna gibba G3
Authors: KESSLER BEZALEL , STEINBERG NATANAEL
Published: April 2006

3′,5′‐cAMP stimulates flowering of Lemna gibba G3 under inductive long‐day conditions and enhances flower onset. 3′,5′‐cAMP has no influence on frond production.

2′,3′‐cGMP increases markedly the proliferation of fronds and inhibits flowering. The effect of 2′,3′‐cGMP on frond multiplication is photoperiodically independent; under short‐day conditions 2′,3′‐cGMP replaces in fact the requirement for inductive long‐day conditions.

2′,3′‐cGMP increases the total amount of DNA per frond. This accumulation of DNA precedes by 2–3 days the 2′,3′‐cGMP related increase in frond formation.

The results are discussed in the light of the hypothesis that the active cyclic mononucleotides exert their effects on multiplication and flowering at the level of DNA.
Art und Menge der Ausscheidung 14C‐markierter Verbindungen bei Chlorella pyrenoidosa unter dem Einfluss des osmotischen Drucks der Nährlösung
Authors: WELLER Von H. , HDFNER W. , LINSER H.
Published: April 2006

Chlorella pyrenoidosa was labelled by 14CO2 and the nature and amount of excreted organic compounds in nutrient media of different osmotic pressure were determined after a 24 h period. The total rate of excretion of organic bound 14C was about 4 μg 14C per mg harvested algal dry matter or 1% of the total 14C content of the algae at the beginning of the excretion period. The main compounds found in the excretions were unidentified substances with a molecular weight higher than 700, amino acids, organic acids and sugars.

The osmotic pressure of the nutrient medium did not affect the total amount of the organic excretions. However, the excreted amounts of some specific compounds differed in respect to the osmotic conditions of the nutrient medium.
Levels of Indol‐3yl‐acetic Acid and Acid Inhibitors in Green and Etiolated Bean Seedlings (Phaseolus vulgaris)
Authors: TILLBERG ELISABETH
Published: April 2006

Indol‐3yl‐acetic acid (IAA) was identified in Phaseolus vulgaris L. Shoot tissue of seedlings, exposed to light for 5 days, had a higher level of IAA than etiolated seedlings of the same age. The content of IAA increased in green seedlings during light treatment for 5–12 days. No increase could be measured in dark‐grown seedlings. Inhibitory substances appeared at different Rf‐values. The main part was identical to the inhibitor‐β complex and occurred in a higher amount in light‐grown seedlings than in etiolated taller ones. One part of the inhibitor‐complex appeared to be abscisic acid (ABA). It is suggested that both IAA and acid inhibitors may play an important role in the control of stem growth and differentiation, although light effects on other hormones and regulatory systems cannot be ignored.
Auxin Balance in the Avena Coleoptile
Authors: RAJAGOPAL R. , LARSEN POUL
Published: April 2006

Coleoptiles of Avena possessed the capacity to degrade infiltrated indole‐3‐acetic acid (IAA). This activity decreased along the length of the coleoptile from apex to base on the bases of fresh weight, dry weight and protein; the apical 1 cm segment degraded more IAA than segments from other parts of the coleoptile. The naturally occurring inhibitor of the IAA oxidase activity increased in concentration up to 20 mm from the coleoptile apex; beyond, it decreased gradually towards the base. The spatial distribution of this inhibitor does not explain the gradient in IAA oxidase activity. Growth in length of the coleoptile and the IAA inactivating capacity of the apical 1 cm segment, increased 5‐ and 4,4‐fold, respectively, between the ages of 70 and 130 h; but auxin secretion into agar platelets by the apical 2 mm of the coleoptile registered only a 2.7‐fold increase. Deseeding and derooting the seedlings reduced the subsequent growth, diffusible auxin content and the IAA oxidase activity of the coleoptiles; derooting proved to be more deleterious than deseeding. A parallel reduction was evident in auxin content and IAA degrading activity following these treatments. Application of the cytokinin 6‐benzylaminopurine (BAP) to coleoptiles of derooted seedlings failed to influence their capacity to degrade IAA. Nor was the activity of the aldehyde oxidase, which converts indole‐3‐acetaldehyde (IAAld) to IAA, affected by such treatment.
In vitro Studies on Pinus
Authors: KONAR R. N.
Published: April 2006

Hypocotyl tissue from Pinus gerardiana was established in culture on White's basal medium supplemented with 2 % sucrose, 10% (v/v) coconut milk, 500 mg/l casein hydrolysate and 1 mg/1 2,4‐dichlorophenoxyacetic acid (2,4‐D).

Various organic and inorganic nutrients were studied in order to determine the specific nutritional requirements of the tissue in vitro. Sucrose, glucose and maltose were equally effective as fixed carbon sources. The inorganic nutrient combination of White's medium was found to be better than that of Murashige and Skoog's medium. White's modified basal medium supplemented with coconut milk, casein hydrolysate and 2,4‐D was the most successful nutrient combination. Glutamine was as effective as casein hydrolysate in promoting growth of the tissue.
The Role of Auxin Metabolism in Root Meristem Regeneration by Pinus lambertiana Embryo Cuttings
Authors: GREENWOOD M. S. , HARLOW C. , HODGSON H. D.
Published: April 2006

Since the existence of root promoting substances that consist of a complex between auxin and another molecule has been suggested, we have examined the role of auxin conversion products in root regeneration by Pinus lambertiana embryo cuttings. Auxin conversion products were detected using radioactive forms of the auxins IAA (indoIe‐3‐acetic acid), NAA (a‐napthaleneacetic acid) and 2,4‐D (2,4‐dichlorophenoxyacetic acid). 10−7M NAA was more effective than 10−6M IAA at promoting rooting, yet it formed conversion products much less rapidly. Also continuous exposure to IAA was necessary for optimum root formation. Based on these and other findings, we conclude that free auxin, and not the conversion products we detected, is essential to root meristem formation.
Measurement of the Five Enzymes which Convert Chorismate to Tryptophan in Wheat Plants (Triticum aestivum cv. Kalyansona)
Authors: SINGH MAHENDRA , WIDHOLM J. M.
Published: April 2006

Conditions are described for measuring anthranilate synthetase, anthranilate‐PRPP‐phosphoribosyl transferase, N‐5′‐phosphoribosyl anthranilate isomerase, indole‐3‐glycerol phosphate synthetase and tryptophan synthetase in crude extracts from Triticum aestivum (wheat) plants. Only the last enzyme has been measured before in extracts from green plants. The extractable quantities of each enzyme in all plant parts at all stages of growth were sufficient to synthesize the amount of tryptophan present within the same tissue in 48 h. Anthranilate synthetase activity was the lowest of the five enzyme activities and was the only one inhibited by tryptophan in vitro, indicating that this enzyme may be the control point in tryptophan biosynthesis in wheat plants.
Abscisic Acid in Prunus Trees: Isolation and the Effect on Growth of Excised Shoot Tissue
Authors: FEUCHT W. , KHAN M. Z. , DANIEL P.
Published: April 2006

The abscisic acid content of the mature shoot tissue of vigorous Prunus avium, medium sized Prunus cerasus and dwarfing Prunus cerasus self (S) was estimated by spectropolarimetry and gas chromatography. There is no correlation between the levels of ABA found in the tissue and the dwarfing potential of the trees investigated. However, Prunus arium stem tissue shows the lowest sensitivity to ABA, whereas the explants of normal and dwarfing Prunus cerasus exhibit a stronger inhibition.
Differential Absorption, Translocation and Metabolism of Metribuzin [4‐amino‐6‐tert‐butyl‐3‐(methylthio)‐as‐triazine‐5(4H)one] by Soybean Cultivars
Authors: SMITH A. E. , WILKINSON R. E.
Published: April 2006

Soybean (Glycine max (L.) Merr.) cultivars have been reported to range in tolerance to injury by 4‐amino‐6‐tert‐butyl‐3‐(methylthio)‐as‐triazine‐5(4H)one (metribuzin), from tolerant (e.g.‘Bragg’) to susceptible (e.g.‘Coker 102’ and ‘Semmes’). ‘Bragg,’‘Coker 102’, and ‘Semmes’ soybeans were grown in sand subirrigated with nutrient solution containing labelled (14C‐carbonyl metribuzin) and nonlabelled metribuzin to determine cultivar variability in absorption, translocation, and metabolism of metribuzin. Plants were periodically harvested, autoradiographed, and radioactivity in tissue extracts quantified. Data indicated that all 3 cultivars readily absorbed and translocated metribuzin. However, ‘Bragg’ tissues accumulated greater quantities of metribuzin metabolites than the other two cultivars. The major 14C‐containing metabolite in ‘Semmes’ and ‘Coker’ roots and stems was 6‐tert‐butyl‐as‐triazine‐3‐5‐(2H,4H)‐dione, whereas the major 14C‐metabolite isolated from‘Bragg’ roots and stems was a glucose conjugate. Results indicated that differential‐intraspecific responses to metribuzin may result from differential capacities for herbicide detoxification by conjugation.
Oscillatory Transpiration and Water Uptake of Avena Plants
Authors: BROGÅRDH TORGNY , JOHNSSON ANDERS , KLOCKARE RUNE
Published: April 2006

The oscillatory transpiration of 6 days old Avena plants was investigated with respect to the water potential of the root medium. The desired water potential was obtained by means of mannitol solutions.

When the water potential was lowered (“mannitol step”), the amplitude of the oscillations decreased. Below –3.0 bars no oscillations persisted. A detailed study was made of the phase changes of the oscillations caused by a short time decrease of the water potential of the root medium (“mannitol pulse”). The duration of these short term treatments was either 9.0, 3.0 or J.5 min.

The experimental results are discussed on the basis of an electric analogue previously presented in the literature. Published simulations based on the model were in clear contrast to the present experimental results as well as to earlier results in the literature. However, simulations in the present paper showed that the model could explain the experimental results if suitable parameter values were chosen.
Temperature Effects on Shoot and Root Development From Begonia × cheimantha Petiole Segments Grown in vitro
Authors: FONNESBECH MOGENS
Published: April 2006

The effect of different temperatures on the shoot and root formation in isolated petiole segments of Begonia × cheimantha was determined after 10 weeks on a modified White medium containing 0.1 mg/1 NAA and 0.5 mg/1 BA.

Temperature proved to be important for the induction of shoot and root formation. At a constant temperature the best plants were obtained at 18 to21°C. If the temperature was higher, fewer cultures survived and the number of roots and shoots were lower. Lower temperatures inhibited the development of plants. A pretreatment at 15 or 18°C for two to four weeks improved the number and size of the shoots developed during a following 24°C treatment. High temperatures throughout the growing period reduced the number of shoots severely. A pretreatment of three days at 24°C or one day at 28°C reduced the shoot number by 50 %. After seven days at 28°C there was not a single shoot in any of the cultures. However, after two weeks at 15 or 18°C it was no longer possible to inhibit the shoot formation by a 24°C treatment.

It is concluded that the formation of shoots in petiole segments takes place during the first two weeks after excision, and that high temperature is detrimental to the shoot initiation process.
Growth Promoting Effect of a Transpiration Suppressant on Cotton
Authors: MUKHERJEE ILABANTA
Published: April 2006

The transpiration suppressant Tag 16 (polyethylene emulsion), which is known to form thin films on leaves, was sprayed on cotton plants grown under varying weather and soil moisture conditions. In hot, dry weather and under restricted water supply 10 and 15% solution of the original Tag 16 promoted extension growth and increased fresh and dry weight of plants. In hot, humid weather three sprays at weekly intervals did not have any effect on plant height, fresh and dry weight, leaf number and flowering.
Protein and Ribonucleic Acid Synthesis by Plant Mitochondrial Systems
Authors: GOSWAMI BISWENDU B. , CHAKRABARTI SYAMALIMA , DUBE D. K. , ROY S. C.
Published: April 2006

The incorporation of 14C‐labelled phenylalanine into proteins of the mitochondrial systems obtained from 48‐h germinating seeds of Vigna sinensis (L.) Savi can be stimulated by polyuridylic acid [poly (U)] and depressed by rifampicin, which is, however, ineffective if poly (U) is allowed to interact with the incorporating system before the antibiotic has access to it.

A system consisting of a mitochondrial S‐100 fraction and ribosomes from the same source with other cofactors can bring about polymerization of phenylalanine.

The incorporation of 14C‐labelled uracil into RNA by the plant mitochondria is greatly dependent on the exogenous addition of adenine, guanine, cytosine and also on 5‐phosphoribosyl‐l‐pyrophosphate (5‐PRPP). It is greatly suppressed by rifampicin and ethidium bromide.
Ethylene and the Regulation of Apple Stem Growth under Stress
Authors: ROBITAILLE H. A. , LEOPOLD A. C.
Published: April 2006

Bending stree resulted in an increase in the ethylene concentration in the internal atmosphere of apple stem (Malus domestica Borkh. cv. Winesap). reaching a maximum at about 2 days after bending. The rise in ethylene content was followed by a depression of growth at about 14–21 days. Ethylene content returned to control levels after about 3 weeks. Application of a past naphthaleneacetic acit caused a similar increase in ethylene levels, and the application of ethephon pastes brought about an inhibition of elongation growth. Whereas stress treatment resulted in an inhibition of growth in stem diameter as well as elongation of growth in stem diameter as well as elongation, the ethephon applications resulted in a stimulation of growth in diameter. It is suggested that ethylene may be involved in the growth responses to mechanical stress.
Callus and Root Formation in Explants of Beta vulgaris
Authors: WELANDER TORKEL
Published: April 2006

Callus from hypocotyl and petiole explants and anthers of Beta vulgaris L. was initiated on a defined agar medium containing IAA and kinetin. The cultures were kept in light (18 hours a day) at 27C for 5 weeks. Differences in dry matter production and root initiation were found between hypocotyl and petiole explants. No shoots were formed. Callus formation in anthers was very rare.
Changes of Onion Epidermal Cell Permeability Due to the Treatment with Alanap
Authors: FENG K. A.
Published: April 2006

The effect of Alanap, N‐1‐naphthylphthalamic acid (NPA), on the permeability of onion (Allium cepa) epidermal cells was studied by means of a plasmometric method. Urea, 1,3‐dimethylurea, and water were used for the test of permeability.

It was found that the treatment of onion epidermis with NPA at various concentration (5 × 10–3 to 5 × 10–6M) altered the deplasmolysis rates and the absolute permeability constants. However, NPA did not alter the osmotic value of the treated cells. It was suggested that NPA treatment altered the permeability of onion epidermal cells due to the effect of this herbicide on the plasma membrane.
Distribution of Gibberellins and Abscisic Acid in Geotropically Stimulated Vicia faba Roots
Authors: EL‐ANTABLY HAMED M. M. , LARSEN POUL
Published: April 2006

The occurrence of gibberellins and abscisic acid (ABA) in extracts of roots of Vicia faba was demonstrated by gas‐liquid chromatography (GLC) of the methylated eluates from the relevant zones of thin‐layer chromatograms (TLC) of purified extracts. Quantitative determination of the hormone contents in extracts from upper and lower halves of roots which had been kept in the horizontal position for 30 min indicated a redistribution of the hormones during the geotropic stimulation. Gibberellins whose methyl esters appeared at the retention time of methylated gibberellic acid (GA3), used as a standard, occurred in higher concentration in the upper than in the lower halves (ratio 2.08:1), whereas the concentration of ABA was highest in the lower halves (ratio 3.08:1). The ratio of the hormones in right and left halves of vertical roots was close to 1:1. Indoleacetic acid (IAA) and ABA were found to retard the elongation of roots of Vicia faba and Lepidium during the first 24 h. Additional experiments with Lepidium showed that this retardation occurs within the first hour after application. Low concentrations of GA3, when applied to germinating seeds just after the radicles had broken the seed coat, stimulated root elongation in Vicia faba within 24 h and in Lepidium within 36 h. When applied to Lepidium seedlings with 20 mm long roots, GA3 showed a stimulatory trend within the first 2 h, and distinct stimulation in the subsequent hours, particularly at the lowest concentrations, 0.01 and 0.001 mg/1. These results suggest the possibility of a participation of ABA and gibberellins (in addition to IAA) in the development of the positive geotropic curvature.
The Action of Kinetin in Improving the Water Balance and Delaying Senescence Processes of Cut Rose Flowers
Authors: MAYAK S. , HALEVY A. H.
Published: April 2006

Kinetin delays the fading of cut rose (Rosa hyb. cv. Golden Wave) flower shoots exposed to water stress conditions. Using leafless flower shoots (i.e., a plant system devoid of stomates), we demonstrated that the main initial effect of kinetin was on increasing water uptake and petal growth. Later, kinetin slowed down processes associated with both senescence and stress (RNase activity and dry weight reduction), and maintained petal turgidity for an extended period.
Nitrate Reductase and Glucose‐6‐phosphate Dehydrogenase Activities as Influenced by Leaf Age and Addition of Protein to Extraction Media
Authors: SCHRADER L. E. , CATALOG D. A. , PETERSON D. M. , VOGELZANG R. D.
Published: April 2006

Lea fage influences the level of activity and the decay rate of the enzymes nitrate reductase (NR: E.C. 1.6.6.1) and glucose‐6‐phosphate dehydrogenase (G6PD; E.C. 1.1.1.49) extracted with and without protein in the extraction media. Such influence was determined in three plant species: corn (Zea mays L.), oats (Arena sativa L.), and tobacco (Nicotiana tabacum L.). Leaves of different ages were obtained from plants of various ages, or by removal of leaf blades from different positions on a single shoot. NR activity (per g fresh weight) declined as leaves of these plant species became older, especially when extraction was effected with conventional media (i.e. without added protein). The instability of NR in these extracts increased as leaves became older. Decay of NR in vitro was exponential with time. Addition of protein [3 %(w/v) casein or bovine serum albumin] to extraction media markedly increased the level of NR activity and its stability, especially in older leaves of all three plant species. Addition of protein did not affect the level of G6PD extracted from corn leaf blades, but slightly enhanced its activity in extracts from the oldest leaf blade of oats. G6PD activity also declined as leaf blades of corn and oats became older.
Identification of Cell Division Inducing Compounds from Coconut Milk
Authors: VAN STADEN J. , DREWES S. E.
Published: April 2006

The use of chromatographic techniques coupled with mass spectrometry, infra‐red analysis and nuclear magnetic resonance revealed that the amino acid phenylalanine might be responsible for a large proportion of the cell division activity of coconut milk as determined by the soybean bioassay. The observation that zeatin can be removed very readily by partitioning against ethyl acetate at alkaline pH values, cautions against inclusion of this method as a purification step for extracting cytokinins from plant extracts. Mass spectrometry revealed the presence of an unidentified cell division substance with a molecular ion of 279 and which co‐chromatographed with zeatinriboside on Sephadex LH‐20.
The Uptake of 63Ni by the Diatom Phaeodactylum tricornutum
Authors: SKAAR HARALD , RYSTAD BRITT , JENSEN ARNE
Published: April 2006

Kinetic studies of the uptake of 63Ni by cultures of the diatom Phaeodactylum tricornutum Bohlin revealed that the uptake capacity of the cells depended strongly on their metabolic state. Phosphate‐starved cells gave saturation‐type uptake curves and had low nickel‐binding capacity. This was increased markedly by the addition of phosphate to the cultures. When nickel ions were added before or together with the phosphate, the increase in nickel‐binding capacity of phosphate‐starved cells failed to appear more or less completely. Uptake of phosphate and formation of polyphosphate by the cells were not affected by the addition of nickel to the growth medium. The phosphate dependent synthesis of the principle involved in nickel binding was induced 15–20 h after the addition of phosphate to starved cells. Whether phosphate was directly or indirectly involved in this process could not be established.
Effect of Aflatoxins on the Changes in Fats and Carbohydrates during Germination and on the Symbiotic Fixation of Nitrogen in Peanuts [Arachis hypogaea]
Authors: SINGH RANGIL , SINGH AJIT , VADHERA SHYAMA , BHATIA I. S.
Published: April 2006

The rate of hydrolysis of fats during germination of peanuts decreased with the increase in the concentration of aflatoxins. Free‐reducing sugars increased up to 96 h of germination, and thereafter their concentrations remained more or less constant. However, the rate of formation of free‐reducing sugars decreased with increase in the concentration of aflatoxins. At all the stages of germination the rate of formation of sucrose decreased with increase in the concentration of aflatoxins. The aflatoxins stimulated the fixation of nitrogen during the preflowering stage, leading to an increase in the concentrations of soluble nitrogen in roots and protein in shoots: the maximum amount of total nitrogen fixed and that excreted into the soil was at a concentration of 2.5 μg/ml aflatoxins.
Effect of Abscisic Acid and Other Plant Hormones on Growth of Apical and Lateral Buds of Seedlings
Authors: BELLANDI DEISE MAURI , DÖRFFLING KARL
Published: April 2006

The effect of abscisic acid (AbA) on the growth of lateral and apical buds was studied in seedlings of Pisum sativum and some other species. The hormone was applied in three different ways: 1) directly to the lateral bud on the second node of decapitated pea seedlings as 5 μI droplets in an ethanolic solution; 2) to the cut surface of decapitated seedlings: 3) to the apical bud of intact plants.

AbA directly applied in amounts of 5 to 0.1 μg to the lateral bud of the second node of decapitated seedlings had a strong inhibitory effect on the bud. Application to the cut surface of seedlings decapitated about 5 mm above the second node resulted in slight inhibition of the lateral bud on the second node and in growth promotion of the bud on the first node. When AbA at 10 to 0.1 μg was applied to the apical bud of intact seedlings, the growth of this bud was inhibited but the lateral buds grew out.

It is concluded that the release of the lateral buds from apícal dominance is the result of the inhibitory effect of AbA on growth of the apical bud and of low transport of AbA. This conclusion is supported by application of GA3 and IAA, individually and each combined with AbA.
Aspartate Kinase from Some Higher Plants and Algae
Authors: AARNES HALVOR
Published: April 2006

Regulation of aspartate kinase activity was examined in some higher plant seedlings (Helianthus annuus, Raphanus sativus, Cucutnis sativus, Sinapis alba), a green (Chlorellapyrenoidosa), and a blue‐green alga (Anacystis nidulans). In Cucumis sativus a concerted feedback regulation by L‐lysine and L‐threonine was indicated. In all the other species examined, aspartate kinase was inhibited by both L‐lysine and L‐threonine and it depended upon the species which of them was the strongest inhibitor. Only slight effects of L‐leucine, L‐isoIeucine and L‐valine were observed, except in the Sinapis alba enzyme.
Enzyme Activities in Urtica dioica: Effects of Daylength and Leaf Age on Glutamate Dehydrogenase, Aspartate Aminotransferase and Alanine Aminotransferase
Authors: WELANDER MARGARETA
Published: April 2006

Enzymes, important to protein synthesis, were investigated in young and old leaves of Urtica dioica. The plants, divided into two groups, were exposed to either 18‐hour or 12‐hour photo‐periods. One group of plants from each photoperiodic regime was subjected to an irradiance of 28 W × m‐2, and the other group of plants to 42 W × m‐2. The enzymes investigated were glutamate dehydrogenase (GDH), aspartate aminotransferase (glutamate‐oxaloacetate transaminase, GOT), and alanine aminotransferase (glutamate‐pyruvate transaminase, GPT), GDH and GOT were determined by means of electrophoretic separation on polyacrylamide and spectrophotometric measurements. GPT was determined only by the latter method.

Plants exposed to 18‐hour photoperiods showed much higher GDH activity than did those exposed to 12‐hour photoperiods. The activity of GDH also increased with leaf age. Besides one uniform NAD+‐dependent GDH, two other NAD+‐independent enzymes, showing GDH activity, were identified on polyacryl‐amide gel electrophoresis. The distribution of NADH and NAD+‐dependent GDH activity between young and old leaves was similar under different growth conditions.

The activity of GOT was insensitive to environmental changes. The results regarding GPT indicate that this enzyme responded to different photoperiods in the same way as GDH. A correlation coefficient of 0.928 was obtained for the relationship between GDH and GPT activity.
Nitrate Reductase Activity of Wheat Seedlings during Exposure to and Recovery from Water Stress and Salinity
Authors: PLAUT ZVI
Published: April 2006

Nitrate reductase activity was inhibited as a result of reduced soil moisture potentials or application of NaCI to nutrient solutions. The decrease in enzyme activity of wheat seedlings exposed to salinity, was found 24 hours after exposure to stress. The effect of stress on nitrate reductase was found in cell‐free extracts as well as in riro in assays of intact leaf sections.

A recovery in enzyme activity was found after irrigation or after removal of seedlings from salinity. While relative water content of the leaves was restored within 3 hours after removal of stress, full recovery of enzyme activity occurred only after 24 hours.

Cycloheximide and chloramphenicol suppressed the activity of nitrate reductase in non‐stressed seedlings, but had no effect on the activity of plants exposed to salinity. However, during removal of stress, cycloheximide prevented completely the recovery of nitrate reductase, while chloramphenicol did not interfere with the recovery of the inhibited enzyme activity. It is concluded that a fraction of nitrate reductase may be located in the cytoplasm and lost activity during stress, probably due to inhibited protein synthesis. Another fraction which may be associated with chloroplasts, was inhibited by stress due to conformational changes or partial denaturation.
Changes in Sapwood of Roots of Norway Spruce, Attacked by Fomes annosus. Part I
Authors: JOHANSSON MARTIN , THEANDER OLOF
Published: April 2006

Chemical and physiological changes occurring in root sapwood of Norway spruce (Picea abies [L.] Karst.), when attacked by Fomes annosus (Fr.) Cke, were studied. The transformation of sapwood to reaction zone, induced by the fungal attack, implies a very sharp increase of carbonate content, correlated with higher amounts of potassium, calcium and magnesium. The buffer capacity of the reaction zone is strong, especially in the pH range 6–9. The high peroxidase activity in the rays of the sapwood is almost totally absent in the reaction zone, probably due to inactivating phenolic compounds. o‐Diphenol oxidase was detectable only in the presence of microorganisms. p‐Diphenol oxidase was active in connection with decaying wood but not in the reaction zone.
Sorption of Heavy Metal Cations by Corn Mitochondria and the Effects on Electron and Energy Transfer Reactions
Authors: BITTELL J. E. , KOEPPE D. E. , MILLER RAYMOND J.
Published: April 2006

The passive sorption of Pb+2, Cd+2, Zn+2, Co+2, Ni+2, and Mn+2 by isolated corn mitochondria was determined, and, except for Pb+2, the maximum sorption for each cation was about 58 nmol per milligram of protein. Sorption of Pb+2 was apparently ten times greater, but precipitation may have been the cause of this larger value. The effects of Pb+2, Cd+2, Zn+2, Co+2, and Ni+2 on acceptorless rates of electron transport for three substrates were determined. Greater than 50% inhibitions of oxidation were observed for succinate after additions of >0.1 mM Cd+2, Zn+2, or Pb+2: for NADH after additions of >0.5 mM Cd+2 or Zn+2; and for malate + pyruvate after additions of >0.1 mM Cd+2. Some inhibition of the rate of substrate oxidation was observed for most cations at higher concentrations. Coupling, as measured by ADP/O ratios, was inhibited at lowest concentrations by Cd+2 or Zn+2 and at higher concentrations by Co+2 or Ni+2. Substantial swelling of mitochondria oxidizing succinate was observed following additions of O.1 mM Cd+2 or Pb+2, Correlations are drawn between the effects of Pb+2, Cd+2, Zn+2, Co+2, and Ni+2 and their sorption to mitochondrial membranes.
Nonuniform Transport of Phosphorus from Single Roots to the Leaves of Zea mays
Authors: STRYKER R. B. , GILLIAM J. W. , JACKSON W. A.
Published: April 2006

The postulate that single roots of Zea mays transport their absorbed phosphorus nonuniformly to the leaves was tested. Plants were grown under growth chamber conditions for three to four weeks in nutrient solution. At this stage of growth a series of plants was placed into a system in which two roots on each plant were allowed to absorb either 33P or 32P from uptake solutions for time intervals of up to 24 hours. Plants subsequently were harvested such that each leaf was partitioned into samples containing tissue from one side or the other of the midrib. All samples were assayed for 33P and 32P and the results were expressed as the amount of total P transported into different plant parts from a single root.

Nonuniform P accumulation in the leaves occurred and different patterns of accumulation, dependent on the type of root chosen for uptake were observed. Nearly uniform P accumulation occurred between one side and the other of a given leaf when transport was from radicle roots. In marked contrast, transport from adventitious roots resulted in an alternating pattern of accumulation between one side and the other of each successive leaf up the stem. The seminal root system supplied more P to the older leaves than did the adventitious root system. The nature of these nonuniform P transport patterns is attributed to the vascular organization between roots and leaves.
Action of Abscisic Acid on Auxin Transport and its Relation to Phototropism
Authors: NAQVI SHAMSHAD M. , ENGVILD K. C.
Published: April 2006

The action of abscisic acid on the kinetics of auxin transport through Zea mays L. (cv. Goudster) coleoptiles has been investigated. Abscisic acid applied simultaneously with indoleacetic acid‐2‐14C in the donor block reduced the transport intensity without materially affecting the basipetal velocity or the uptake. No effect on acropetal transport was observed. The data have been used to discuss the similarities in effects of abscisic acid and visible radiation and a hypothesis is proposed to explain the phenomena of phototropism.
Effect of Potassium Supply on the Transport of Photosynthates to the Fruits of Tomatoes (Lycopersicon esculentum)
Authors: MENGEL KONRAD , VIRO MAIJA
Published: April 2006

In experiments with intact tomato plants the effect of potassium on the translocation of photosynthates was studied. Four series of plants were grown in nutrient solutions with two different potassium levels (K1 and K2 treatments). When the fruits of the first truss had developed the plants were treated with labelled CO2 for 2 h in a glove box. The plants were then divided in roots, stems, fruits and leaves, which were prepared for chemical analysis.

In all experimental series the plants with the higher K supply grew better and therefore assimilated higher amounts of labelled CO2 (cpm/plant). The assimilation rates per g fresh material, however, were not increased in each experimental set by the K2 treatment. The absolute quantities of labelled photosynthates transported from leaves and stems to the fruits were also greater in the plant with the higher potassium supply. In all experimental series the proportion of labelled material found in the fruits was higher in the plants of the K2 treatment (total label of the plant=100%) than in the plants of the K1 treatment. This beneficial effect of potassium was also observed in cases, where potassium had not affected the CO2 assimilation rate. Expressing the distribution of labelled material in relative terms (percentage proportions) means that the effect of CO2 assimilation on the transport of photosynthates was excluded to a high extent. The higher percentage proportions of labelled material found in fruits and roots of the K2 as compared to the K1 treatment is, therefore, predominantly dependent on a specific effect of potassium on the translocation of assimilates.

The labelled material found in the soluble fraction of the stems consisted of about 90% sugars, nearly half of which was sucrose, the rest being mainly glucose and fructose. This finding suggests that sucrose is the most important transport form of carbohydrates in tomatoes.
Constitutive Uptake of Choline Sulfate by Roots and Leaf Slices of Barley
Authors: NISSEN PER
Published: April 2006

Barley roots take up choline sulfate constitutively via 3 separate, homogeneous mechanisms which obey Michaelis‐Menten kinetics and have, respectively, low, high, and very high affinity for the sulfate ester. Leaf slices possess only the low‐and the high‐affinity mechanism. These are both inhibited by dini‐trophenol and NaF but are differently affected by solute analogues. Uptake via the high‐affinity mechanism is active; the low‐affinity mechanism has also characteristics of facilitated diffusion.
Calcium Uptake by a Psychrophilic Achromobacter Strain
Authors: LEDEBO INGRID
Published: April 2006

The permeability of a psychrophilic Achromobacter strain to calcium ions was examined with the radioisotope 45Ca2+. The amount of radioactivity that remained associated with the cells after exposure to 5 to 200 mM solutions of radioactive calcium was determined. The concentration of 45Ca2+ of the cells compared to that of the surrounding medium gave a ratio larger than one, and this ratio increased with decreasing ambient calcium concentration. The same results showed that the higher the external calcium concentration was, the more calcium remained with the cells. The radioactivity of the cells had the following characteristics: 1. It was rapidly lost when the cells were washed with 40Ca‐solution. 2. Most of it was retained after water washings. 3. It was not affected by the presence of 2,4‐dinitrophenol. 4. It was only slightly affected by temperature. 5. It increased when the cells were treated with toluene or heat and reached a maximum of 2–3 times the value of untreated cells. The same treatment brought about a smaller increase of the uptake of 22Na+. 6. Approximately 60% of the radioactivity of whole cells was associated with isolated cell envelopes.
Evidence for Compartmentation of Tryptophan in Cultured Plant Tissues: Free Tryptophan Levels and Inhibition of Anthranilate Synthetase
Authors: WIDHOLM J. M.
Published: April 2006

1. Anthranilate synthetase activity in crude extracts from tissue cultures of Daucus carota L. (carrot), Nicotiana tabacum L. (tobacco; cv. Wisconsin 38 and xanthi), Glycine max Merr. (soybean) and Oryza sativa L. (rice) was completely inhibited by l‐tryptophan (5 to 50 μM). Mutant carrot and tobacco lines, capable of growth in the presence of 5‐methyltryptophan, required 500 to more than 1000 μM tryptophan for complete inhibition of enzyme activity, respectively.

2. Except for the mutant tobacco line, the concentrations of free tryptophan in all tissue cultures tested were greater than the levels necessary to completely inhibit the respective anthranilate synthetase activities in vitro. These findings would indicate that much of the free tryptophan is compartmentalized away from the regulatory enzyme, anthranilate synthetase. This could implicate compartmentalization of the inhibitor as a biosynthetic control mechanism.

3. During the growth of normal and mutant carrot tissues the anthranilate synthetase enzyme must be at least 7.8 and 10.8% active, respectively, in order to accumulate the amount of tryptophan found in the tissues.

4. Of the substrates and cofactors required for anthranilate synthetase activity in vitro, Mg2+ and glutamine were present at near optimal levels in the carrot and tobacco tissues, but chorismate was found to be significantly below the optimal concentrations.