bluuebunny/crossref_metadata_2025 huggingface dataset:
Tissue Tensions during Cell Elongation in Wheat Roots and a Comparison with Contractile Roots
Authors: BURSTRÖM H. G.
Published: April 2006

A study has been made of tissue tensions in growing Triticum roots. After the initial phase of elongation with both a lateral and an exponential longitudinal growth, the tissues are under strong longitudinal stress. Plasmolysis in situ or splitting of the root in the pericyclic region causes an increase in length of the perivascular part. Freed from the stele the perivascular part contracts on plasmolysis. During the following only longitudinal growth, the stress decreases under decreased root diameter. When elongation has ceased, the root in situ contracts on plasmolysis. It is suggested that during radial growth longitudinal stresses are built up, which are released when the stele catches up with the growth of the cortex. The similarity to conditions in contractile roots of Arum (Lamant and Heller 1967) is pointed out. A difference is found in the polarity of growth and thus in the mode of release of the stresses. The cause of the tensions and methodical difficulties are discussed.
Effects of Indole‐3‐acetic Acid and Gibberellin on Synchronous Cultures of Chlorella fusca
Authors: LIEN TORLEIV , PETTERSEN RUNE , KNUTSEN GJERT
Published: April 2006

The applicability of synchronous cultures of Chlorella fusca as a reproducible experimental system for the study of growth regulators has been investigated using indole‐3‐acetic acid (IAA) and gibberellin.

None of these compounds stimulated growth or sporulation.

IAA inhibited growth and sporulation at concentrations higher than 6 × 10−5M, the effect increasing with increasing acidity. Gibberellin had no effect.
Investigation on the Assimilation of Nitrogen by Maize Roots and the Transport of Some Major Nitrogen Compounds by Xylem Sap
Authors: INGVERSEN J. , IVANKO S.
Published: April 2006

The amino acid and protein metabolism of roots of maize has been studied. The important role of the free amino acids and proteins of the roots as active agents in nitrogen assimilation is pointed out. Nitrogen supplied as nitrate is preferably incorporated into α‐ketoglutaric acid, and then by trans‐aminases transferred to other ketoacids. In the case of ammonia supply the function of a nitrogen‐accumulating assimilation system leading to the formation of Arg, Glu‐NH2 and Asp‐NH2 is shown.
Growth Regulators in Populus tremula
Authors: ELIASSON LENNART
Published: April 2006

Shoots grown out from aspen root sections in light or in darkness were extracted and the content of growth‐regulating substances in various fractions was determined with the Avena coleoptile straight‐growth assay. The most obvious difference was obtained for the inhibitor β fraction. This was about ten times more active in the light‐grown than in the dark‐grown shoots. Some indications of more growth inhibitory material in ether‐insoluble fractions of light‐grown plants were also obtained. The stimulation obtained at the Rf of indol‐3‐yl‐acetic acid was somewhat lower in the etiolated shoots than in the light‐grown ones.
Soluble Carbohydrates in the Bark of Italian Prune (Prunus domestica) Trees
Authors: BRAUN J. W. , HELTON A. W. , LeTOURNEAU DUANE
Published: April 2006

Bark samples were removed from 1‐year‐old stems of Italian prune trees at intervals throughout the growing season (June–August). Glucose, fructose, sucrose, traces of raffinose and a polyol were detected in ethanolic extracts of the bark. The polyol was isolated and shown to be d‐glucitol. The use of insoluble polyvinylpyrrolidone proved to be the best method for decolorizing bark extracts prior to quantitative analysis of ethanol‐soluble carbohydrates by paper chromato‐graphic methods. Glucitol was the major carbohydrate in the bark throughout the season. Sucrose was the major sugar, decreasing gradually as the season advanced. Fructose and glucose were found in lesser and about equal amounts. The amount of glucitol, glucose and fructose was high in June, decreased to a minimum in mid‐July, increased sharply in late July and early August and decreased later in the season.
Interaction between K‐Deficiency and Light in 14C‐Sucrose Translocation in Bean Plants
Authors: AMIR S. , REINHOLD LEONORA
Published: April 2006

The effect of K deficiency on sucrose transport was studied in bean plants from which the cotyledons had been removed soon after germination and which were subsequently grown in culture solution. Labelled sucrose wassupplied to the primary leaf.

Mild Kdeficiency depressed translocation. A statistically significant interaction between the presence of K and light was observed. K deficiency had no effect on translocation if the plants had been placed in the dark before the experiment and remained in the dark during the translocationperiod.

Maximum correction for differences in the specific activity of the sugar being translocated, as between control and K‐deficient plants (based on sugar analyses in various plant parts), failed to abolish the K effect when the amount of sugar applied was relatively low (high specific activity). On the other hand no effect of K‐deficiency was observed on translocation when the amount of applied sugar was high (low specific activity). In this case 14CO2 fixation was greatly reduced in the controls, but not in the K‐deficient plants. Significant interaction existed between added sugar and K‐deficiency on 14CO2 fixation. All results reported here can be explained on the basis of a scheme whereby K plays a rôle in reversible intermediate steps between sugar formation in the chloroplast and the entry of this photosynthesised sugar into the “translocation pool” where it mixes with exogenous sugar.
Effects of Colchicine and Light on Cell Form in Fern Gametophytes. Implications for a Mechanism of Light‐induced Cell Elongation
Authors: MILLER JOHN H. , STEPHANI MARILYN C.
Published: April 2006

Spores of the fern, Onoclea sensihilis L., suffer a disruption of normal development when they are cultured on media containing colchicine. Cell division is inhibited, and the spores develop into giant spherical cells under continuous white fluorescent light. In darkness only slight cell expansion occurs. Spherical cell expansion in the light requires continuous irradiation. Photosynthesis does not seem to be involved, since variations in light intensity do not affect the final cell diameter; the addition of sucrose to the medium does not permit cell expansion in darkness; and the inhibitor DCMU does not block the light‐induced cell expansion. Continuous irradiation of colchicine‐treated spores with blue, red or far‐red light produces different patterns of cell expansion. Blue light permits spherical growth, similar to that found under white light, whereas red and far‐red light promote the reestablishment of polarized filamentous growth. Although ethylene is unable to induce polarized cell expansion in colchicine‐treated spores in darkness or white and blue light, it enhances filamentous growth which already is established by red or far‐red irradiation. Both red and far‐red light increase the elongation of normal filaments (untreated with colchicine) above that of dark‐grown plants, but under all 3 conditions the rates of volume growth are identical. Light, however, does cause a decrease in the cell diameters of irradiated filaments. These data are used to construct an hypothesis to explain the promotion of cell elongation in fern protonemata by red and far‐red light. The model proposes light‐mediated changes in microtubular orientation and cell wall structure which lead to restriction of lateral cell expansion and enhanced elongation growth.
Metabolism of Indole‐3‐acetaldehyde. III. Some Characteristics of the Aldehyde Oxidase of Avena Coleoptiles
Authors: RAJAGOPAL R.
Published: April 2006

Coleoptiles of Avena contain a soluble enzyme system, capable of oxidizing indoleacetaldehyde (lAAld) to indoleacetic acid (IAA). There is a gradient in the concentration of the enzyme along the length of the coleoptile and the first inter‐node. The top 5 mm segment of each organ is relatively richer in this enzyme than the rest of the tissue. The enzyme was purified 17.7‐fold by fractional precipitation with ammonium sulphate followed by gel filtration on Sephadex. Optimal pH for lAAld oxidation is ca. 4.4. Activity of the enzyme is normally oxygen obligatory. But, in the absence of oxygen, phenazine methosulphate (PMS) serves as hydrogen acceptor for aldehyde oxidation, but not some other dyes tried. Approximately one mole of oxygen was consumed for each mole of IAA formed. Formation of H2O2 could not be detected. Added H2O2 inhibited the reaction.

Prolonged dialysis progressively inactivated the enzyme. Added NAD, NADP, FMN, FAD, cytochrome c, cyanoco‐balamin, folic acid and ascorbic acid did not restore the lost activity. But 10−3M cysteine restored about 60 % of the lost activity. The enzyme is an acidic protein, isoelectric at pH 4.05. For lAAld, under the conditions of experimentation, a Km of 3.45 × 10−4M was calculated. Besides lAAld, indole‐3‐aldehyde and phenylacetaldehyde served as substrates, but not acetaldehyde, propionaldehyde, salicylaldehyde, xanthine, hypoxanthine or catechol. Cyanide, dithionite and mercapto‐ethanol totally inactivated the enzyme depending upon the concentration and duration of treatment. X‐ray irradiation up to a dosage of 2900 r promoted the lAAld oxidizing activity of cell‐free preparations made from irradiated coleoptiles. As yet, no cofactor requirements have been found for the activity. The enzyme is unlikely to be a pyridino‐ or a flavoprotein.
The Utilization of Carbohydrate and Nitrogen Reserves by Taxus During Its Spring Growth Period
Authors: MEYER MARTIN M. , SPLITTSTOESSER WALTER E.
Published: April 2006

The spring growth and the utilization of carbohydrate and nitrogen reserves in this growth was studied in Taxus media cv. Hicksii plants 0, 2, 4 and 6 weeks after the plants started growing in the spring. The effect of nitrogen applied the previous season on the storage and utilization of the carbohydrate and nitrogen reserves during spring growth was determined. The plants were separated into buds (all new growth), stems, needles (those produced the previous season) and roots and analyzed for changes in total nitrogen, basic and non‐basic amino acids, total available carbohydrate, sugars, hemicelluloses, organic acids and chlorophyll.

The bulk of the soluble nitrogen reserves were stored as arginine in the stems and old needles. With the onset of spring growth, arginine nitrogen was converted to other amino acids which accumulated in the new growth (buds). The roots, stems and needles of plants grown under high nitrogen levels always contained more total nitrogen than those grown under low nitrogen levels.

The bulk of the carbohydrate reserves were stored as hemicelluloses. The plants grown under high nitrogen levels utilized the bulk of the carbohydrate reserves from the roots and smaller amounts from the stems and old needles, while plants grown under low nitrogen levels used only the reserves in the roots. In the low nitrogen plants, carbohydrates accumulated in the needles and stems.

Both the carbohydrate and nitrogen reserves were important in the dry weight increase due to spring growth. However, the nitrogen reserves were the limiting factor and the high nitrogen plants grew twice as much, produced more chlorophyll, and utilized more nitrogen and carbohydrate reserve in spring growth than low nitrogen plants. The additional chlorophyll allowed the production of more carbohydrates and these additional carbohydrates were used in increased growth rates, while in the low nitrogen plants the carbohydrate produced was less and accumulated within the plant.
Specific Effects of Kinetin on the Uptake of Monovalent Cations by Sunflower Cotyledons
Authors: ILAN I. , GILAD TAMAR , REINHOLD LEONORA
Published: April 2006

Kinetin promoted the uptake of K+ and Rb+ into detached sunflower cotyledons. This action was concomitant with an acceleration of growth. A slighter promotion of Li+ uptake was also noted, but there was no consistent influence on that of Na+. A small inhibitory effect on NH4+4 uptake was apparent when the latter was computed per average weight of sample during the course of incubation. Light also promoted the growth of the cotyledons, but depressed their capacity to absorb potassium.

The action of kinetin on cotyledons removed from 5–7 day old seedlings was weaker than on those removed from 2–4 day old seedlings with regard to growth but stronger with regards to K+ uptake. When K+ uptake by cotyledons taken from 7‐day old seedlings was followed with time the kinetin effect was already detectable within a few hours, but it became more pronounced after 10 hours' incubation.

Kinetin did not accelerate growth or K+ uptake in hypo‐cotyl segments. IAA, which was previously shown to promote these processes in hypocotyl segments, inhibited them in cotyledons. A working hypothesis is suggested according to which endogenous auxins and cytokinins regulate the absorption of K+ in shoot cells of the intact plant in a manner similar to that in which they act in excised tissues and in this way affect the distribution and redistribution of K+ in the shoot; and that they are among the factors which determine the selectivity of ion uptake in the intact plant.
Investigation on the Assimilation of Nitrogen by Maize Roots and the Transport of Some Major Nitrogen Compounds by Xylem Sap
Authors: IVANKO S. , INGVERSEN J.
Published: April 2006

Xylem sap was collected from nitrogen‐starved maize plants and investigations were made on the nitrogen transported. It appears from the results that several pools for different amino acids exist, which have different relations to the transport of nitrogen taken up. While in maize roots Glu, Glu‐NH2 and Arg are transported directly from the place of their synthesis, the transported Asp and Ala predominantly derive from the pool of amino acids synthetized before application of nitrogen. An explanation of this observation is offered.
Relationship between the Inhibitory Effects of 5,6–Epoxyxaiithophylls and Phototropism
Authors: VALADON L. R. G. , MUMMERY ROSEMARY S.
Published: April 2006

Using a range of assay systems, the effect of light on the inhibitory properties of several carotenoids were investigated. The 5,6‐epoxyxanthophylls: violaxanthin, neoxanthin and 5,6‐monoepoxylutein when illuminated were shown to cause inhibition in the various assays, while a certain amount of inhibition also occurred with the dark treatment. The suggestion that phototropism might be the result of light induced formation of inhibitory compounds was also investigated and there was no evidence that the inhibitors obtained by in vitro degradation of 5,6‐epoxyxanthophylls play a part in phototropism.
Some Properties of Inhibitor β from Solanum tuberosum Compared to Abscisic Acid
Authors: HOLST ULLA‐BRITT
Published: April 2006

The growth‐inhibiting effect of inhibitor β, extracted from the potato variety Majestic, was compared with the effect of abscisic acid by means of the Avena coleoptile straight‐growth test. Dose‐response curves showed that total growth inhibition is attained by inhibitor β, but this is never caused by abscisic acid even in high unphysiological doses.

By chromatographic methods inhibitor β can be separated into three active components. One of these is a phenolic substance with weak growth‐inhibiting effect. The two others contribute equally to the inhibitory effect, and one of them is probably abscisic acid.

Beside these inhibiting substances there are components without inhibitory effect, many of phenolic character, included in the inhibitor β complex.
Plant Water Potential Gradients Measured in the Field by Freezing Point
Authors: CARY J. W. , FISHER H. D.
Published: April 2006

A portable freezing point meter was used in the field to measure the water potential gradients in sunflower (Helianthus annuus), beans (Phaseolus vulgaris), corn (Zea mays), wheat (Triticum aestivum), pumpkin (Cucurbita pepo), potato (Solanum tuberosum), alfalfa (Medicago sativa), and sugarbeets (Beta vulgaris). The measurements were made between daybreak and sunrise, and again during the middle of the afternoon on days when the potential evapotranspiration varied between 6.5 and 8.0 mm of water.

The gradients varied from a maximum of 0.2 bar per cm in a wheat, down to an undetectable value for pumpkin. Although most of the soil in the root zone was kept at potentials above –1 bar, the bulk of the root tissue had water potentials of –5 to –10 bars. Differences in water potential between shaded and unshaded leaves, and between leaf tissue and guttation fluid suggested a similar drop of several bars between xylem elements and the surrounding leaf tissue in some plant species. The implications of such drops are discussed with respect to plant water transport equations and pressure cell potential measurements.
The Influence of Oxygen on the Production of Volatile Compounds by Dipodascus aggregates
Authors: NORRMAN JONAS
Published: April 2006

The production of volatile compounds by Dipodascus aggregatus was studied in relation to the oxygen concentration in the medium. Oxygen concentration was determined with a Clark oxygen electrode and volatile compounds in the atmosphere above the culture by a gas chromatographic technique. Shake cultures of the fungus in its stationary phase of growth were very sensitive to a decrease in oxygen concentration in the presence of residual glucose. Anaerobic conditions induced production of volatile compounds that continued for many hours. The pattern of production of volatile compounds observed under conditions of low oxygen concentration during the stationary phase of growth differed from that obtained under aerobic conditions during the exponential phase of growth.
Experimental Studies on Plant Metabolism
Authors: YOUNIS M. E. , FODA H. A. , EL‐GHOBASHY A. S.
Published: April 2006

Treatment of Ricinus communis seeds with GA accelerated the production of reducing sugars and increased the total carbohydrate content. The effect increased progressively with increasing concentration of GA. — GA treatment also induced an earlier appearance of starch which was shown to be completely absent at the early stages of germination. Furthermore, GA accelerated the conversion of oils into carbohydrates. — Analysis of germinating seeds for their nitrogen content showed that whenever an increase in soluble‐N due to GA treatment was detected, there was a decrease in protein‐N. Breakdown of protein and formation of soluble‐N increased progressively with increase in GA concentration. — GA induced variable changes in the length of the radicles and the hypocotyls, the dry weight and the water content of germinating seeds.
Geotropic Responses in Helianthus and their Dependence on the Auxin Ratio. – With a Refined Mathematical Description of the Course of Geotropic Movements
Authors: JOHNSSON ANDERS
Published: April 2006

The paper describes a refinement of a previously published theory for geotropic movements of Helianthus annuus hypocotyls.

The introduction of a logarithmic relation between growth rate and auxin concentration means an extension compared with the previously published approach. It is theoretically and experimentally shown that the refined theory can successfully be linked with reported measurements on lateral auxin transport in geotropically stimulated plant stems.

The non‐linear character of the theory is discussed in connexion with theoretical descriptions on circumnutations of the hypocotyls. The refined theory is shown to predict the amplitude of the circumnutations reasonably well.
Epinastic Thresholds in a Simulated Hypogravity Environment
Authors: CONRAD HERBERT M. , YOKOYAMA K.
Published: April 2006

The morphological changes of several grasses, dicotyledons and thallial plants to decreasing increments of gravity from the normal 1 g to 0 g were determined. The various levels of simulated hypogravity were obtained by regulation of the angles of the rotating clinostats. Reaction to simulated hypo‐gravity is evidenced by leaf, petiole, stem and coleoptile epi‐nasty, root hyponasty in the leafy plants and cereal seedlings and increased lobulation in gametophytes. Threshold response for the gametophyte, marigold, bean and pepper plants was approximately 0.67 x g while that for the wheat, corn and oat seedlings was 0.17xg. The intensity of the epinastic response was found to be inversely related to the gravitational force. With leafy plants, significant responses to reduced gravity are shown only in the presence of light perhaps influencing their ability to synthesize auxin.
Photosynthesis and Stomatal Behavior in Sugarcane Leaves as Affected by Light Intensity and Low Air Flow Rates
Authors: IRVINE JAMES E.
Published: April 2006

Increased air flow and light intensity increased the rate of photosynthesis of attached sugarcane leaves. At constant, low flow rates greater photosynthetic rates, leaf porosity, and stomatal opening accompanied increased light intensity. At constant light intensity, greater photosynthetic rates but lesser porosity and lesser stomatal opening accompanied increased air flow. The highest rate of photosynthesis (53 mg dm–2 h–1) was observed when both air flow and light intensity were at a maximum, even though porosity was minimal and no stomata appeared open. It is concluded that stomataL resistance of sugarcane leaves does not control rates of photosynthesis except when that resistance is very high.
Effects of Some Inhibitors of Nucleic Acid and Protein Synthesis on the Development of Amine Oxidase in Germinating Pea Cotyledons
Authors: SUZUKI YONEZO , YAMASAKI KUNIKO
Published: April 2006

The germination of pea seed was accompanied by a rapid increase of amine oxidase (E.C. 1.4.3.6.) in the cotyledon and over half the increase was ascribable to the presence of axial tissue. The presence of actinomycin D, 6‐methylpurine and cycloheximide in the early period of soaking inhibited markedly the increase in amine oxidase activity. However, actinomycin D and cycloheximide had little effect on the enzyme development when added after one day and 2 days of germination respectively. The amine oxidase development was also inhibited by dl‐p‐fluorophenylalanine, 5‐methyltryptophan, chloramphenicol and phenylthiourea.
Degradation of Indol‐3yl‐acetic Acid in Homogenates and Segments of Cabbage Roots
Authors: RAA J.
Published: April 2006

Plots of reaction rate versus substrate concentration of the enzymatic decarboxylation of IAA yield sigmoid, rather than the usual, hyperbolic curves, suggesting that the IAA oxidase of cabbage roots is an allosteric enzyme. The quantity of this enzyme in roots is so high that the IAA concentration is likely to limit IAA degradation in intact cells. Thus, variations in the level of this enzyme seem not to be essential for the regulation of the endogenous IAA concentration. Cabbage roots contain substances that can inhibit IAA oxidase. These substances are spatially separated from IAA oxidase in intact cells, but the same inhibitors are able to reach the enzyme when added exogenously to tissue segments. The possibility that added IAA is treated by tissue segments in another manner than endogenous IAA is discussed.
Phytochrome‐mediated Carotenoid Biosynthesis and Its Influence by Plant Hormones
Authors: KHUDAIRI A. K. , ARBOLEDA O. P.
Published: April 2006

Lycopenc biosynthesis of parenchyma chromoplasts was studied in detached tomato fruits, Lycopersicum esculentum Mill, cv. Waltham Forcing, and found to be phytochrome mediated. A few minutes of red light during the day enhanced lycopene formation. Far‐red irradiation did not enhance lyco‐pene biosynthesis. Far‐red following red nullified the promotive effect of red light. Lycopene content increased two‐fold in the presence of abscisic acid. Ripening of tomatoes was inhibited when gibberellin, kinetin and ascorbic acid were applied to green tomatoes. Gibberellin (A3) was more inhibitory to lycopene synthesis than kinetin.
First DNA Synthesis around Sterile and Crown Gall‐Inoculated Wounds in Vicia faba
Authors: KUPILA‐AHVENNIEMI SIRKKA , THERMAN EEVA
Published: April 2006

DNA synthesis was measured during a 30 hour period in stem segments containing a wound — either sterile or inoculated with Agrobacterium tumefaciens— and in control stems of Vicia faba. An identical series of experiments was conducted both on upper, still growing internodes and on lower, mature ones. The incorporation of 3H‐thymidine was determined from extracted DNA with a liquid scintillation spectrometer. The results from the two internodes were fairly similar. DNA synthesis was not significantly different in the two types of wounds. It rose above control level at about 10 hours after wounding and reached its peak at about 19 hours. Roughly, this pattern of DNA synthesis seems to correspond to the minimum conditioning and transformation time as found in other plants. However, the decisive factor need not be DNA synthesis, but could be some other process coinciding with it.
Effect of Diurnally Fluctuating vs. Constant Temperatures on Flower Induction and Sex Expression in the Olive (Olea europaea)
Authors: BADR SAYED A. , HARTMANN HUDSON T.
Published: April 2006

Olive trees must be exposed to a period of winter chilling temperatures in order to form inflorescences the following spring. The effects of diurnally fluctuating and constant temperatures on flower induction and sex expression in the olive were compared under controlled environment conditions. The effect on flowering of diurnally fluctuating temperatures depends upon the length of time at the higher temperatures. While daily exposure to the high temperatures (21° to 26°C) for a short period (four hours) intensified the effectiveness of the low temperatures (7° to 12.5°C), when the high temperature duration was 12 hours it counteracted the low temperature action. Possibly, daily low temperatures act to stimulate reactions leading to floral hormone synthesis, while daily short exposures to high temperatures act to maintain metabolic activity, promote energy‐yielding reactions, and possibly stimulate cell‐division activity. In the olive, an intermediate constant temperature (12.5°C) favors both types of reactions and induces flowering; however, in this case, the pistils fail to develop. The olive has very specific temperature requirements for flowering and neither the mean temperature nor the accumulated number of hours below a given value, e.g. 7°C, adequately characterizes these requirements.
Photosynthesis in Sugarcane Varieties Infected with Strains of Sugarcane Mosaic Virus
Authors: IRVINE JAMES E.
Published: April 2006

Symptoms of sugarcane mosaic virus disease caused by strains B and D were accompanied by a reduction in the rate of photosynthesis per unit area; the severe symptoms of strain A and the mild symptoms of strain I produced rates no different from those of healthy plants of variety C.P. 31‐588. All four strains decreased chlorophyll content and increased the amount of light transmitted by the leaf. Photosynthetic rates were reduced less than the reduction of chlorophyll would indicate. Symptoms moderated on older leaves, but rates of photosynthesis per dm2 were less in older leaves of both healthy and diseased plants. Sugarcane varieties differed in their rates of photosynthesis in both healthy and in virus‐infected plants; a significant reduction in photosynthetic rate by sugarcane mosaic occurred in three of the four varieties.
Polyglucan Branching Isoenzymes of Algae
Authors: FREDRICK JEROME F.
Published: April 2006

The cyanophyte, Oscillatoria princeps, and the enigmatic hot‐spring alga, Cyanidium caldarium, contain two branching isoenzymes which can act on amylose and amylopectin, converting these polyglucans into highly branched phytoglycogens. The red alga, Rhodymenia pertusa contains three branching isoenzymes, only one of which is capable of the dual activity of the other algal branching isoenzymes. The other two red algal branching isoenzymes are Q enzymes and can only act on amylose, forming moderately branched amylopectìns. However, when the isoenzymes of all three algae are separated on different concentrations of polyacrylamide gel via electrophoresis, the mobilities of the isoenzymes show that the Q enzymes and the branching enzymes are related and true isoenzymic molecules. They differ only in electrical charges, probably caused by the substitution of amino acid residues in their active peptides. It is possible that if these charge isomers are due merely to amino acid substitutions, the enzymes may have been originally derived from a common catalytic molecule. The study indicates the identity of the branching isoenzymes of Oscillatoria and Cyanidium, and lends further supporting evidence to the cyanophyte origin of the enigmatic alga.
Investigation on the Assimilation of Nitrogen by Maize Roots and the Transport of Some Major Nitrogen Compounds by Xylem Sap
Authors: IVANKO S. , INGVERSEN J.
Published: April 2006

The uptake and assimilation of nitrate and ammonia have been studied in Zea mays. Nitrogen‐starved maize roots are capable of accumulating a potential capacity for nitrogen uptake and assimilation. Reestablishment of nitrogen supply leads to intense uptake, reaching 154 % of the reference variant level after 24 hours when nitrate is supplied, and 121 % when ammonia is supplied. After 24 hours the insoluble nitrogen fraction accounts for 80, 54 and 55 % of the total taken up in the PK + NO3‐, PK + NH4+ and NPK variants respectively.
Interrelations between Gibberellic Acid, Cytokinins and Abscisic Acid in Retarding Leaf Senescence
Authors: BACK A. , RICHMOND AMOS E.
Published: April 2006

The interrelation between the effects of abscisic acid (ABA) and the effects of cytokinins and gibberellic acid in retarding leaf senescence was investigated. Leaf discs from plants of Taraxacum megallorrhizon, Rumex pulcber and Tropaeolum majus were floated on solutions of cytokinin or GA to which given amounts of ABA were added. After five days, chlorophyll was extracted and the amount estimated spectrophoto‐metrically. The interrelation between the effects of abscisic acid and cytokinins differed from that between the effects of ABA and gibberellic acid. Abscisic acid reduced the senescence retarding effect of GA more than that of cytokinins. A high concentration of cytokinins nullified the senescence enhancing effect of low concentrations of ABA. GA did not reverse the effects of ABA.
Autoradiographic Studies of Pear Pollen Tube Walls
Authors: ROGGEN H. P. , STANLEY R. G.
Published: April 2006

Germinating pollen was supplied D‐glucose‐3H and myo‐inositol‐3H. Pollen tube growth was terminated at varying intervals and the cytoplasmic contents removed or left intact. Empty pollen tubes were treated with β‐1,4‐glucanase, β‐1,3‐glucanasc or pectinase and the residual radioactivity was determined. Analysis of autoradiograms showed the pollen tip contained primarily pectin, the subtending cell wall of the tube was primarily cellulose, or possibly hemi‐cellulose, and callose accumulated most heavily toward the rear, older segments of the tube. Callose was also heavily formed in the tip region of non‐growing tubes. Pectin formed from myoinositol appeared to be solubilized, or removed, from the wall to the cytoplasm with aging of the pollen tube.
Abscisic Acid As A Ribonuclease Promoter
Authors: LESHEM Y.
Published: April 2006

By means of experimentation with the barley endosperm system and with peroxidase isoenzyme production during culture of tobacco pith the mode of action of abscisic acid (ABA) was investigated. Gibberellic acid (GA3) promoted reducing sugar production was significantly inhibited by ABA and bovine pancreas ribonuclease (RNase), while the specific RNA polymerase inhibitor rifamycin was without effect. In tobacco pith culture, ABA promoted appearance of induced isoenzymes, the effect being completely checked by rifamycin. Furthermore ABA significantly inhibited, and GA3 promoted production of RNA in treated tobacco plants. It is suggested that the mode of ABA action in these systems may be an inductive one on the degradative enzyme, RNase, and not necessarily a negative one on the promotive RNA polymerase. This conclusion implies effect on some preexisting RNA, the breakdown of which is mediated by ABA‐activated RNase.
Die Wirkung einer Vorbestrahlung auf den Wuchsstoffgehalt von X‐2‐Pflanzen bei Brassica oleracea var. acephala Von
Authors: BRUGOVITZKY EDITH
Published: April 2006

The Effect of Pre‐irradiation on the Content of Growth Substances in Xi‐Plants of Brassica oleracea var. acephala. The auxin content of growth stimulated young plants (Brassica oleraceav ar. acephala) of the X2‐generation, originating from X‐ray irradiated seeds (75 kR) was determined. Methanolic extracts were separated on thin‐layer‐chromatograms, which were analyzed by ultra‐violet light and various chemical reactions. Quantitative determinations of growth substances were made using the Avena‐coleoptile‐cylinder‐test. The following results were obtained: 1. X2‐plants had a higher content of IAN compared with unirradiated control samples; 2. IAAm was detectable in only two out of 40 experiments; 3. Two fluorescent substances were detected: a hydroxycinnarmc acid derivative and a long chained unsatu‐rated ketone or aldehyde, which is still unknown.
Changes of Starch Synthetase Activity of Cucumber Leaves during Ammonium Toxicity
Authors: MATSUMOTO H. , WAKIUCHI N. , TAKAHASHI E.
Published: April 2006

The changes of granule bound starch synthetase activity in cucumber leaves (Cucumis sativus L. cv. Suisei No. 2) were investigated during ammonium toxicity. Generally speaking the quantity of starch granules of injured plants were less than that of normal plants. ADPG is a more effective glucose donor to starch synthesis than UDPG. It was found that the starch synthetase activity of injured plants was decreased compared to the normal plants. This variation of enzyme activity was higher when UDPG was used as glucose donor. The addition of K+ and NH4+ generally inhibited the enzyme activity when UDPG was used as glucose donor, but stimulated it when ADPG was used. This stimulation was found to be more effective in enzymes prepared from injured plants than from normal plants. The level of potassium bound to starch granules was not changed markedly between normal and injured plants.
A Definition of Optimum Nutrient Requirements in Birch Seedlings. II
Authors: INGESTAD TORSTEN
Published: April 2006

The aim of the experiments described was to specify further the nutrient requirements of birch seedlings. A growth method is described in which the nutrients consumed at maximum growth of birch seedlings can be replaced, without change of the nutrient solution, by means of additions made as pH and conductivity titrations so that three conditions are satisfied: 1) All necessary mineral nutrients are present in the plant in optimum proportions. 2) The nitrogen sources NH4+ and NO3‐ are present in the nutrient solution in an optimum ratio. 3) Total concentration in the solution is optimum. The three conditions may be regarded as criteria in a definition of nutrient requirements. The possible use of criterion 1 as an expression of the optimum nutrient status is also discussed. A considerable increase in light intensity had no significant effect on the optimum nutrient proportions or the optimum total concentration. A tendency to lower ammonium uptake in relation to nitrate was induced when both nitrogen sources were present. Simple stock nutrient solution systems are listed and discussed.
Studies on the Germination of Pine Pollen (Pinus mugo) in vitro. III. Inhibition by D‐Mannose and Deoxyhexoses
Authors: NYGAARD PER
Published: April 2006

D‐Mannose, 2‐deoxy‐D‐glucose, 6‐deoxy‐D‐galactose, and 2‐deoxy‐D‐galactose inhibit germination of pine pollen (Pinus mugo Turra) probably competitively with a metabolizable sugar. Inhibition by D‐mannose, 2‐deoxy‐D‐glucose, or 6‐deoxy‐D‐galactose is reversed by transfer of pollen to sucrose medium, if the inhibitors was added before tube growth has started. In contrast, inhibition by 2‐deoxy‐D‐galactose is irreversible except after very short exposures to the inhibitor, in which case the transfer results in reduced growth and germination.

Incubation with 2‐deoxy‐D‐glucose, 6‐deoxy‐n‐galactose, or 2‐deoxy‐D‐galactose after tube growth has started, results in irreversible inhibition of growth. If D‐mannose is used, growth is resumed if the pollen are transferred to sucrose medium. Addition of D‐mannose or lowering of the temperature prior to incubation with the deoxyhexoses protected against the irreversible growth inhibition.

Uptake of oxygen and 32P‐labelled phosphate is reduced upon addition of either of the inhibitors.
Variants of Myxococcus virescens Exhibiting Dispersed Growth. Growth and Production of Extracellular Enzymes and Slime
Authors: HASKÅ GUNO , STÅHL STEN
Published: April 2006

The growth of two strains of Myxococcus virescens exhibiting dispersed growth was followed in casamino acids (N III‐C) media and casitone media. The changes in optical density, pH, pigmentation as well as the secretion of bacteriolytic and proteolytic enzymes, DNA and polysaccharides during growth were recorded.

In both media the bacteria grew exponentially with a generation time of 4 (casitone) and 20 hours (N III‐C) respectively. The maximal cell mass was about 4 times higher in casitone than in casamino acids media.

The amounts of bacteriolytic enzymes produced by the two strains in N III‐C medium were different but in casitone medium they were about equal and considerably higher. The maximal values of proteolytic enzymes were about the same in both media and always occurred later than the bacteriolytic maxima. Both activity peaks appeared before the phase of decline.

The polysaccharide production reached a maximum during the stationary growth phase in both media. A higher value was reached during growth in casitone medium than in N III‐C medium. During the phase of decline a second increase of polysaccharide in the medium appeared. No DNA could be detected in the cell‐free solutions until the beginning of the phase of decline.
Indole‐3‐Pyruvic Acid as an Intermediate in the Conversion of Tryptophan to Indole‐3‐Acetic Acid. I. Some Characteristics of Tryptophan Transaminase from Mung Bean Seedlings
Authors: TRUELSEN T. A.
Published: April 2006

Seedlings of mung bean (Phaseolus aureus) contain a soluble enzyme capable of converting l‐tryptophan to indole‐3‐pyruvic acid by transamination. The concentration of the enzyme is highest in the stem meristem and primary leaves and lowest in the roots. The enzyme was purified 28.6 fold by ammonium sulphate precipitation, Sephadex G‐200 filtration, and electrophoresis. The isoelectric point of the enzyme protein was pH 6.6. The optimum pH and temperature for the catalytic conversion were ca. 8.5 and 53°C respectively. Using l‐tryptophan and α‐ketoglutarate as substrates Km was found to be 3.3 × 10−4 M and the activation energy 18,270 cal per mole. The enzyme converted only the l‐form of tryptophan, phenylalanine, tyrosine, and histidine. Out of 13 other l‐amino acids tested 8 could be transaminated. Eight α‐keto acids tested could all be used as substrates. High efficiency of an α‐keto acid as an amino group acceptor agreed usually with high efficiency of the corresponding amino acid as a donor. The pari ß‐methyl‐α‐ketoisovaleric acid and isoleucine was an exception to that rule. Addition of pyridoxalphosphate to the reaction mixture was not needed.

The indole‐3‐pyruvic acid formed in the reaction was trapped and partly stabilized as its borate complex and measured spectrophotometrically at 327 nm. The keto acid formed was further identified by chromatography of its 2,4‐dinitrophenylhydrazone in 4 solvent systems. When using α‐keto‐glutaric acid as a substrate, the glutamic acid produced was determined by the glutamate dehydrogenase method. The sensitivity of the assay permits enzyme determinations in extracts from 5 mg leaves or 100 mg roots.
Effects of Growth Retardants on Norway Spruce (Picea abies)
Authors: DUNBERG ARNE , ELIASSON LENNART
Published: April 2006

Young seedlings of Picea abies Karst, grown in nutrient solution were treated with the growth retardants Amo‐1618, B‐995, and CCC. These were added to the nutrient medium. B‐995 and CCC retarded root and shoot growth in the concentrations 100, 10, and 1 mg/l. Growth was almost entirely inhibited by 300 mg/l, obviously due to toxicity. The effects of Amo‐1618 were similar but more varying. GA counteracted the effects of all the retardants on shoot growth, but not on root growth.
The Effects of Mercury Compounds on the Growth and Orientation of Cucumber Seedlings
Authors: PUERNER NORMA J. , SIEGEL SANFORD M.
Published: April 2006

Mercuric chloride alone, in admixture with fluorescein or chemically combined as mercurochrome inhibited cucumber growth and induced disorientation of root and shoot. The inhibitory effects of Hg‐ion were reduced but the disorienting (ageotropic) effects enhanced by the presence of fluorescein. In addition to mercury, nine other elements were tested at concentrations up to 100 mg/l (as metal ion). Disorientation was induced by Zn, Ag, Cd, In, Pt and Hg. Pb and Au were not toxic, but Ga and Tl were too inhibitory to permit disturbances in orientation.
Antigen‐Antibody Crossed Electrophoresis of Soluble Proteins in Different Strains of Spirulina
Authors: LINDBLOM MARIANNE
Published: April 2006

Soluble proteins from three strains of the blue‐green alga Spirulina were compared by antigen‐antibody crossed electrophoresis. The three algal strains were shown to contain at least two immunologically identical proteins. Differences between all three strains were found among proteins with low electrophoretic mobility. Antigen‐antibody crossed electro‐phoresis is a very sensitive method and could be used as a complement to morphology and other characteristics when comparing different algal strains.
Spinach Chloroplast Membranes after Differential Lipid Extraction
Authors: YAO VIVIANA J. , STERLING CLARENCE , STOCKING C. RALPH
Published: April 2006

Chloroplasts from spinach were fixed in glutaraldehyde and extracted with three different lipid solvents, after which the lipid composition was analyzed. Studies were also made with the electron microscope. In cold dry acetone, which removes 75 % of lipids, the basic structure of the membranes is unchanged. Acetone with 10 % water removes 89 % of the lipids and a mixture of chloroform with methanol removes 93 % of the lipids, both solvents leaving nearly unrecognizable membrane structures. The relationship between lipid composition and membrane structure is discussed.
The Effect of Coumarin on Growth, Production of Dry Matter, Protein and Nucleic Acids in Roots of Maize and Wheat and the Interaction of Coumarin with Metabolic Inhibitors
Authors: SVENSSON SVEN‐BÖR JE
Published: April 2006

Effects of coumarin on fresh weight, dry matter, protein and nucleic acid content per cell in attached roots of maize and wheat and in whole excised elongation zones of maize were determined. The inhibition in cell length exerted by coumarin did not correspond to an inhibition of the net synthetic capacity. Coumarin treatment increased the cell surface, the production of dry matter and the protein content per cell. The dry matter and the protein content per unit surface was slightly increased or unaffected. The effect of coumann on cell shape seemed to be independent of that on dry matter production and net protein synthesis. The same was found in excised elongation zones. —The net DNA‐synthesis per cell was slightly increased in attached roots by coumann treatment, but this effect was probably not correlated with the morphogenetic changes. Inhibition of DNA‐synthesis with hydroxyurea did not alter the coumarin induced changes in cell shape. —The net RNA‐synthesis per cell was slightly decreased after coumarin treatment, but the net RNA‐synthesis per cell and the morphogenetic effects exerted by coumarin were not related with each other. Inhibition of m‐RNA‐synthesis with actinomycin D did not prevent the effects of coumarin on cell division, cell expansion, dry matter production and net protein synthesis. The same was true for inhibitors of protein synthesis, puromycin and p‐fluorophenyl‐alanine. The findings are in support of the view that coumarin affects already existing structures or enzymes. —Comparisons between coumarin and the uncouplers, DNP and dicoumarol, showed that the effects of coumarin were not, solely, due to uncoupling. SH‐protecting agents, BAL, DTE and glutathione, did, with few exceptions, not reduce the morphogenetic effects of coumarin.
Effets du NaCl sur ľactivité de la nitrate réductase chez deux variétés halophiles: Suaeda maritima var. macrocar pa et var. flexilis
Authors: BOUCAUD JEAN
Published: April 2006

The nitrate reductase activity of Suaeda maritima var. macrocarpa and var. flexilis grown on nitrate‐rich substrates with 1 to 23 g/1 NaCl is maximum after 30 days of culturing.

Compared to the substrate with the lowest salt content, the activity increase obtained with 7.5 g/1 of NaCl is greater in the more halophilous variety (var. macrocarpa). Even though the NaCl docs not operate directly on the induction and activity of nitrate reductase, it is responsible for this increase by modifying the CO2 assimilation and protein synthesis.
Inhibition of the Development of a Cation Accuniulatory System and of Tris‐induced Uptake in Storage Tissues by N6‐benzyladenine and Kinetin
Authors: VAN STEVENINCK R. F. M.
Published: April 2006

The effect of N6‐benzyladenine (BA) and kinetin on cation uptake in disks of beetroot (Beta vulgaris L.) and swede (Brassica napobrassica Mill.) tissue was measured in aerated solutions, containing 1 mM NaCl or 1 mM KCl, and in the presence or absence of trishydroxymethyl ammo methane (tris) buffer at pH 8. This investigation followed a suggestion that the immediate activation of cation uptake in freshly sliced beetroot disks by tris (the tris‐effect) may depend on stimulation of hexokinase activity. BA, a competitive inhibitor of hexokinase, caused a complete inhibition of tris stimulated cation uptake in beetroot disks, but the effect was delayed and preceded by a 3–4 hour period of promoted cation uptake. Generally, the effects of BA and kinetin were identical. Use of 14C‐kinetin indicated a rapid incorporation of kinetin into the tissue. BA and kinetin also prevented the development of a cation uptake capability during the aging of the beetroot disks. Swede disks which do not show a tris‐effcct and no lag phase in development of cation uptake capability were not affected by BA and kinetin treatments. Mechanisms of tris induced cation uptake are discussed with emphasis on its role as a proton acceptor.
Effect of Menadiol Disulfate on the Phylloquinone Content of Wheat (Triticum aestivum)
Authors: JANSSON OWE
Published: April 2006

Seedlings of Triticum aestivum L. were sprayed with menadiol disulfate in water solution. Eight days after spraying, the content of phylloquinone in the shoots was more than twice as high as in shoots of untreated control plants. The application of menadiol disulfate caused a stimulation of the synthesis of phylloquinone. It is possible that menadiol is an intermediate in the biosynthesis of phylloquinone.
Entrainment of Geotropic Oscillations in Hypocotyls of Heliunthus annuus– An Experimental and Theoretical Investigation
Authors: ANDERSEN H. , JOHNSSON A.
Published: April 2006

A theory for the geotropic movements of the Heliunthus unnuus hypocotyl has been given earlier by Johnsson et ul. In the present paper this theory is tested by extensive experiments. The magnitude as well as the rate of geotropic curvature are found to be in agreement with the theoretical predictions.

Further, the geotropic reaction time, defined as the time between the start of geotropic stimulation and the start of the geotropic reaction is determined as a function of the stimulation angle with respect to the plumb line. A slight variation found in the reaction time is included in the theory.