bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

AbstractThe 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

AbstractShoots 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

AbstractBark 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

AbstractThe 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

AbstractSpores 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

AbstractColeoptiles 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

AbstractThe 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

AbstractKinetin 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

AbstractXylem 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

AbstractUsing 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

AbstractThe 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

AbstractA 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

AbstractThe 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

AbstractTreatment 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

AbstractThe 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

AbstractThe 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

AbstractIncreased 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

AbstractThe 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

AbstractPlots 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

AbstractLycopenc 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

AbstractDNA 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.