bluuebunny/crossref_metadata_2025_split huggingface dataset:
Triterpeneglycosides as Inhibitors of Fungal Growth and Metabolism 3. Effect on Uptake of Potassium, Magnesium and Inorganic Phosphate
Authors: OLSEN ROLF A. 
Published: April 2006

AbstractA venacin, the resistance factor in oat roots against Ophiobolus graminis var. graminis, and a related triterpeneglycoside, aescin, inhibited the uptake of K+ and Mg2+ in the fungal mycelium both in phosphate and succinate buffers. The uptake of the cations in Neurospora crassa was similarly inhibited when the inhibitors were dissolved in phosphate or acetatebuffer, while no decrease in the uptake of K+ and Mg2+ was observed when the inhibitors were dissolved in succinate buffer. The uptake of cations in Aspergillus niger and Pythium irregulare was more or less unaffected by aescin. The uptake of inorganic phosphate was in no case inhibited, but some decrease of the accumulation of inorganic phosphate in Ophiobolus graminis and Ncurospora crassa due to inhibitor treatment in phosphate buffer was observed.No accumulation of Ca2+ was observed in any of the tested fungi.
Studies of the Biochemical Background to Differences in Glucosinolate Content in Brassica napus L. II. Administration of Some Sulphur‐35 and Carbon‐14 Compounds and Localization of Metabolic Blocks
Authors: JOSEFSSON EGON 
Published: April 2006

AbstractThe aim of the investigation was to study the differences in the metabolism of substances that are utilized in the synthesis of glucosinolates between the Brassica napus cv. Bronowski, which is very low in glucosinolate content, and a cultivar (cv. Regina II) that contains approximately average amounts of these compounds.By experiments in which the plants were grown in nutrient solutions supplied with sulphate‐35S, it was shown that the rate of sulphate uptake was similar in the two cultivars. No accumulation of intermediate metabolites could be demonstrated by autoradiography in Bronowski.Sulphate‐35S, methionine‐35S, methionine‐2‐14C, 2‐amino‐6‐(methylthio)caproic acid‐2‐14C, and S‐(β‐d‐glucopyranosyl)‐4‐pentenethiohydroximic acid (desulpho‐3‐butenylglucosinolate) (glucose‐U‐14C or 35S) were fed to shoots of the two cultivars. After incubation, the plant material was extracted with methanol. The extracts were separated into various fractions, and in some experiments glucosinolates or derivatives of their degradation products were isolated. When measuring the radioactivity of the various fractions or isolated products, the incorporation of radioactivity into glucosinolates was found to be poor in Bronowski from sulphate, methionine, and 2‐amino‐6‐(methylthio)caproic acid. Desulpho‐3‐butenyl‐glucosinolate was an efficient precursor of 3‐butenylglucosinolate in Bronowski, but a poor precursor of 2‐hydroxy‐3‐bute‐nylglucosinolate, which suggests a metabolic block at the hydroxylation step in this cultivar. In Regina II desulpho‐3‐butenylglucosinolate was a good precursor of both 3‐butenylglucosinolate and of 2‐hydroxy‐3‐butenylglucosinolate, which demonstrates that these glucosinolates may be synthesized without prior formation of the corresponding co‐methylthioalkyl glucosinolates and that the hydroxylation can take place after the formation of desulpho‐3‐butenylglucosinolate.The results indicate that the low glucosinolate content of Bronowski is caused by block(s) in the separate pathway leading to the biosynthesis of glucosinolates.
Chloroplasts, Kinetin and Protein Synthesis
Authors: RICHMOND AMOS E. , SACHS BETSY , OSBORNE DAPHNE J. 
Published: April 2006

AbstractThe effect of kinetin on protein synthesis of isolated chloroplasts was investigated by following the incorporation of 14C‐leucine into isolated chloroplasts from Nicotiana tabacum. The incorporation activity varied greatly during the year, being largest in the winter and smallest in the summer. Conversely, the relative effect of kinetin on the incorporation of 14C‐leucine, whether applied as a pretreatment to the leaves or directly in the incubation medium, was largest in the summer and smallest or absent altogether in the winter. Kinetin did not prolong the net incorporation period, which lasted about 40 min, but only enhanced the initial rate of the reaction. Chloroplasts extracted from leaves that had been detached for 24 or 48 h displayed very little of their original, pre‐aged incorporation activity and treating the leaves with kinetin did not, essentially, prevent this loss. It was concluded that the major effect of kinetin upon chloroplasts may be related primarily to an effect upon hydration and permeability of the chloroplast and its membranes, and not to an effect directly upon its machinery for protein synthesis.
The Effect of Reaction Media on the Coupling and Uncoupling of Respiration in Corn Mitochondria
Authors: KOEPPE D. E. , MILLER RAYMOND J. 
Published: April 2006

AbstractThe coupling and uncoupling properties of isolated corn mitochondria were analyzed using three substrates in Tris buffered sucrose and KC1 reaction medias containing inorganic phosphate (Pi), bovine serum albumin (BSA), or Pi and BSA. In these media, without other cofactors, respiratory control (RCR) and ADP/O ratios, and the respiratory burst affected by dinitrophenol (DNP), gramicidin D, calcium chloride and ADP were measured. Bovine serum albumin enhanced the respiratory burst caused by DNP and gramicidin D in the absence of Pi, and in most instances enhanced the stimulation of oxygen uptake by ADP and calcium chloride in the presence of Pi. Mitochondria oxidizing succinate, malate‐pyruvate or NADH exhibited better RCR and ADP/O ratios in buffered 200 mM KCl than they did in buffered 300 mM sucrose. In all instances RCR and ADP/O ratios were enhanced in reaction medias containing BSA.
A Modified Method for Extraction and Identification of Abscisic Acid and Gibberellin‐like Substances from the Olive (Olea europaea)
Authors: BADR SAYED A. , MARTIN GEORGE C. , HARTMANN HUDSON T. 
Published: April 2006

AbstractA procedure for extracting and identifying plant hormones, particularly abscisic acid (ABA) and the gibberellins (GA) was developed through modification of methods described in the literature. The procedure is particularly useful for studying more than one hormone simultaneously in a given sample, and when the supply of plant material is limited.The procedure was used to isolate ABA and GA‐like substances from olive tissue (i.e., leaves, buds and inflorescences). Gibberellin‐like substances were identified by their action on α‐amylase release from embryoless barley half‐seeds.Characterization of an acidic inhibitor extracted from olive inflorescences by thin‐layer chromatography, fluorescence under ultraviolet light, gas chromatography, and physiological effects on wheat coleoptile sections indicate that this inhibitor, or at least a component of it, is very similar if not identical with at least one isomeric form of synthetic abscisic acid.
Carbohydrate Uptake and Metabolism of Ophiobolus graminis
Authors: RAADE P. E. 
Published: April 2006

AbstractThe carbohydrate nutrition of Ophiobolus graminis, the cause of the take‐all disease of wheat, was investigated in growth and respiration experiments. In a synthetic medium, d‐mannitol was the only carbohydrate of thirteen studied which the fungus could not use for growth. However, the fungus was found to take up mannitol by an active mechanism, which was stopped by 2,4‐dinitrophenol.Di‐ and trisaccharides were hydrolyzed extracellularly, and the monosaccharides were assimilated at different rates.
Photosynthesis and Transpiration as a Function of Gaseous Diffusive Resistances in Orange Leaves
Authors: KRIEDEMANN P. E. 
Published: April 2006

AbstractThe CO2 and H2O vapour exchange of single attached orange, Citrus sinensis (L.), leaves was measured under laboratory conditions using infrared gas analysis. Gaseous diffusive resistances were derived from measurements at a saturating irradiance and at a leaf temperature optimum for photosynthesis. Variation in leaf resistance (within the range 1.6 to 60 s cm‐1) induced by moisture status, or by cyclic oscillations in stomatal aperture, was associated with changes in both photosynthesis and transpiration.At low leaf resistance (ri less than 10 s cm‐1) the ratio of transpiration to photosynthesis declined with reduced stomatal aperture, indicating a tighter stomatal control over H2O vapour loss than over CO2 assimilation. At higher leaf resistance (ri greater than 10 s cm‐1) changes in transpiration and photosynthesis were linearly related, but leaf resistance and mesophyll resistance were also positively correlated, so that strictly stomatal control of photosynthesis became more apparent than real.This evidence, combined with direct measurements of CO2 diffusive resistances (in a ‐O2 gas stream) emphasised the presence of a significant mesophyll resistance; i.e., an additional and rate limiting resistance to CO2 assimilation over and above that encountered by H2O vapour escaping from the leaf.
Investigations on Cytokinins. I. Effect of 6‐Benzylaminopurine on Growth and Starch Content of Lemna minor
Authors: JONG JUDITH G. TASSERON‐DE , VELDSTRA H. 
Published: April 2006

AbstractAn excessive starch accumulation in the fronds of Lemna minor L. was observed microscopically and confirmed by direct starch determinations after application of growth inhibiting 6‐benzylaminopurine concentrations. As a high growth rate was coupled with a low starch content and vice versa, the influence of the cytokinin on growth and starch content was compared. It appeared that apart from the expected influence of the growth rate on the starch content, 6‐benzylaminopurine favoured starch accumulation also by itself.
Investigations on Cytokinins. II. Interaction of Light and Cytokinins as Studied in Lemna minor
Authors: JONG JUDITH G. TASSERON‐DE , VELDSTRA H. 
Published: April 2006

AbstractIn Lemna minor under non optimal growth conditions, due to light shortage, a cytokinin is able to supplement this shortage partly. The cytokinin seems to substitute the effect of non‐photosynthetic light.
Oxygen Diffusion from the Roots of Rice Grown under Non‐waterlogged Conditions
Authors: ARMSTRONG W. 
Published: April 2006

AbstractThree rice varieties, cv. Norin 36, cv. Norin 37 and cv. Yubae, were grown in a loam with a 20 cm water‐table which gave aerobic conditions to a depth of not less than 15 to 17 cm. Under these conditions Norin 36 grew more vigorously and tillered more frequently than the other two varieties.The rates of oxygen diffusion at 23°C from roots up to 11 cm in length were however appreciably lower for Norin 36 (4.3 × 10−8g · cm−2 of root surface · min−1) than for Norin 37 or Yubae (c. 7.8 × 10−8g).A considerable increase (up to 200 %) in the oxygen diffusion rate (ODR) from the roots occurred if they were cooled to 3°C, and at this temperature differences in ODR between the varieties were not significant. For a purely physical system, because of the decrease in the diffusion coefficient of oxygen in water, and, the increase in oxygen solubility, a drop of c. 20 % in ODR should accompany the above 20°C drop in temperature. A 16 % drop was recorded for artificial ‘roots’ under these conditions. It was concluded that respiratory activity at the higher temperature must have been responsible for the low readings and intervarietal differences observed at 23°C.By increasing the 3°C values by 25 % a mean value of 14.2 × 10−8g · cm−2 of root surface · min−1 was recorded for the three varieties, being the probable ODR at 23°C in the absence of a respiratory factor. Calculations show that respiratory activity removed enough oxygen to reduce the ODR for Norin 36 by more than 9 × 10−8g, and for Norin 37 and Yubae by c. 6.7 × 10−8g · cm−2 of root surface · min−1.Anatomical investigations showed that cortical breakdown was always extensive at 4 to 4.5 cm from the apex of the roots. In some cases however breakdown had not occurred in the basal segment of the root. No opinion could be formed as to whether differences in the amount of cortical breakdown between the varieties might have occasioned the respiratory differences observed.An interesting feature of the root anatomy was the failure of breakdown in those regions of the roots through which lateral roots emerged.
The Response of Transpiration Resistance to Leaf Temperature as a Desiccation Resistance Mechanism in Tree Seedlings
Authors: WUENSCHER JAMES E. , KOZLOWSKI THEODORE T. 
Published: April 2006

AbstractTranspiration rate and leaf transfer resistance to water vapor loss were determined under a range of leaf temperatures for Quercus macrocarpa, Q. velutina, Q. alba, Q. rubra, and Acer saccharum. Transfer resistance increased with rising leaf temperatures between 20 and 40°C in all species, but the rate of increase in resistance was greatest in species which normally occupy xeric sites. Increased transfer resistance with rising leaf temperature may be significant in preventing rapid desiccation of leaves under the large evaporative stress imposed by high leaf temperature.
A Requirement for DNA Synthesis during Auxin Induction of Cell Enlargement in Tobacco Pith Tissue
Authors: MAHESHWARI M. G. , NOODÉN L. D. 
Published: April 2006

AbstractIAA (indoleacetic acid) is known to induce cell enlargement without cell division in tobacco pith explants grown on an agar medium without added cytokinin. The very long lag period before IAA (2 × 10−5M) stimulates growth, about 3 days, can be useful to study the metabolic changes which lead to the promotion of growth. When the disks are transferred to a medium without IAA after 2 days or less of treatment with IAA, the IAA does not stimulate growth. Disks transferred after 3 days, subsequently show an auxin response, almost as great as those given IAA continuously. At 5 × 10−4M, 5‐fluorodeoxyuridine (FUDR), which inhibits DNA synthesis by blocking formation of thymidylate, completely suppresses the lAA‐induced growth if it is added together with the IAA or 1 day later. When the FUDR is given 2 days after the IAA, there is a small increment of auxin‐induced growth, and an even greater amount if added after 3 days. The period when exogenous auxin must be present to stimulate growth corresponds to the period of FUDR sensitivity. The FUDR inhibition is prevented by thymidine but not by uridine. Other inhibitors of DNA synthesis, hydroxyurea and fluorouracil, also inhibit auxin‐induced growth. Thus DNA synthesis seems to be required for auxin induction of cell enlargement in tobacco pith explants. In contrast, FUDR does not inhibit auxin‐induced growth in corn coleoptile and artichoke tuber sections.
Nitrate Uptake by Roots as Regulated by Nitrate Reduction Products of the Shoot
Authors: ZIONI A. BEN , VAADIA Y. , LIPS S. HERMAN 
Published: April 2006

AbstractA mechanism is proposed by which secondary products of nitrate reduction in the shoot control the uptake of nitrate by the roots. KNO3 enters the roots and is translocated to the shoot where nitrate is reduced and, at the same time, malate is produced. The reduction of nitrate is stoichiometric to the synthesis of malate (1). Part of the K‐malate moves down to the root system in which malate is oxidized, yielding KHCO3 which exchanges for KNO3.Nitrate reduction in the shoot promotes the synthesis of malate which, after its translocation to the root, allows the preferential uptake of nitrate. Thus, plants reducing large amounts of nitrate may take up the anion without a superfluous accumulation of the cation. Furthermore, the utilization of nitrate by the shoot regulates its uptake by the root.
Factors Affecting Flower Abortion and Malformation in Roses
Authors: MOE ROAR 
Published: April 2006

AbstractThe formation of blind shoots and malformed flowers in rose plants grown under various temperatures and light intensities, and subjected to different cut back procedures has been studied.Low temperature, low light intensity and low cut back promoted blind shoot formation. Hybrid tea cultivars are more sensitive for unfavourable temperature, light and cut back treatments than Floribunda cultivars. The process of floral abortion is initiated during the early stages of shoot growth before the differentiation of floral parts has been completed. Low temperatures (12–15°C) in this critical stage of development strongly promote blind shoot formation, but have no effect when stamen and pistil primordia had been formed in the apical flower bud.The formation of malformed flowers, so‐called “bullheads”, which have significantly more petals than normal flowers, is also promoted by low temperature and low cut back. Light intensity seems to have no effect. Shoots subjected to low temperature (12°C) during the early stages of development, before the differentiation of the floral organs are fully completed, produce malformed flowers to a greater extent than shoots subjected to high temperature (18–24°C) during this period.It is suggested that blind shoot formation in roses is subject to hormonal control.
Activity and Compartmentation of Photosynthetic Carboxylases in Normal and Chloroplast‐mutant Maize Leaves
Authors: H.‐NAGY ANNA , PACSÉRY MARIA , FALUDI‐DÁNIEL ÁGNES 
Published: April 2006

AbstractThe activity of ribulose‐l,5‐diphosphate carboxylase (RudiP‐carboxylase) and phosphoenolpyruvate carboxylase (PEP‐carboxylase) measured in vitro was independent from the chlorophyll content of the leaves. The relatively high activity of PEP‐carboxylase as compared to the RudiP‐carboxylase activity was particularly pronounced in the mutants. Realization of the potential (in vitro measured) carboxylating activities in fixation of CO2in vivo was practically complete in normal leaves. In the mutants, however, CO2 fixation was lower than the level permitted by the carboxylase activity. This could be explained only in part by the impaired rate of photophosphorylation. Compartmentation of PEP‐carboxylase was different in normal and mutant leaves: in contrast to the normal ones, parenchyma‐sheath cells of the mutants exhibited high PEP‐carboxylase activity. Competition of PEP‐carboxylase with RudiP‐carboxylase for CO2 in the mutants led to accumulation of organic acids, and can account for their low photosynthetic activity.
Uptake of Sulfate by Roots and Leaf Slices of Barley: Mediated by Single, Multiphasic Mechanisms
Authors: NISSEN PER 
Published: April 2006

AbstractThe uptake of 10−1M–2.5 × 10−1M sulfate by roots and leaf slices of barley can be described by a single isotherm having, respectively, 8 and 5 phases with regularly increasing kinetic constants. Each phase covers a limited concentration range and obeys Michaelis‐Menten kinetics. The uptake of sulfate is proposed to be rate‐limited by a single mechanism or structure which is located in the plasmalemma (or cytoplasm) and which changes characteristics at certain discrete external concentrations (inflection points). Examination of published data indicates that the uptake of other inorganic ions by higher plant cells is also mediated by single, multi‐phasic mechanisms.
Decarboxylation and Transport of Auxin in Segments of Sunflower and Cabbage Roots. II. A Chromatographic Study Using IAA‐1‐14C and IAA‐5‐3H
Authors: AASHEIM TORBJÖRN , IVERSEN TOR‐HENNING 
Published: April 2006

AbstractThe polar movement of IAA has been examined in 5‐mm root segments of Brassica oleracea and Helianthus annum. The movement was studied partly with IAA‐1‐14C and partly with IAA‐5‐3H. In both plants a slight acropetal flux of 14C and IAA‐3H was found through the segments. The recovered radioactivity in the agar receiver blocks and in the receiver end of the segments increased as a function of time.A large portion of the applied IAA was converted on the cut surfaces and in the tissues of the segments. Chromatographic analysis indicated different destruction products when estimated by scintillation counting and by spraying with in‐dole reagent (DMCA).Chromatograms run in isopropanol: ammonia: water, 8:1:1, yielded three different substances, one spot near the starting line and one near the front, neither of which has been identified. Finally there was a spot with Rf 0.4–0.6, probably representing IAA.
Metabolic Changes in Developing Rice Seeds
Authors: PAUL A. K. , MUKHERJI S. , SIRCAR S. M. 
Published: April 2006

AbstractMetabolic changes in developing rice seeds were studied with respect to respiration, carbohydrate and nitrogen fractions, nucleic acids and hydrolytic enzymes, viz. α‐amylase, adenosine triphosphatase (ATPase) and phytase. — Respiration rate was maximum after 12 days from the date of pollination and became feeble afterwards with the fall in the moisture content of the maturing seeds. In the early stage, there was a preponderance of reducing sugars which were replaced later by nonreducing forms. Dry matter accumulation was mainly due to the steady rise in starch content. There was a gradual accumulation of protein nitrogen throughout the experiment, the rate being highest between 12–16 days. RNA content increased steadily till the seeds became mature, while DNA formed rapidly during the first 20 days and was maintained at the same level thereafter. —α‐Amylase activity increased up to 20 days and declined sharply afterwards. The peak activities of ATPase and phytase were recorded at 32 and 24 days after pollination, respectively.
Thermal Inactivation of Plant Growth: Effects on Cotyledon Metabolism
Authors: RAMESHWAR AKULA , STEPONKUS PETER L. 
Published: April 2006

AbstractTemperature exposures which normally decrease growth of Pisum sativum seedlings by 50 % were found to be lethal in plants whose cotyledons were removed. Utilization of the two major reserves, starch and protein, decreased at high temperatures. However, the two enzymes responsible for their hydrolysis were thermostable. It appears that the influence of high temperatures on seedling growth is not due to direct effects of temperature on cotyledon metabolism, but rather indirectly through the axis.
The Relationship between Flower Abortion and Endogenous Auxin Content of Rose Shoots
Authors: MOE ROAR 
Published: April 2006

AbstractThe amount of endogenous growth substances in stem, flowers and leaves of rose plants grown under different temperature and light conditions has been determined.It appeared to be two main growth promoting factors in the acidic fraction of the ether extract. One of them is assumed to be an auxin, probably indol‐3yl‐acetic acid (IAA); the other is not identified. The level of auxin was much higher in extracts from shoots grown at high temperature than in shoots grown at low temperature. Increasing light intensity also seemed to increase the auxin content of the shoots. Shoots which developed after a high cut back of the rose stem had a higher auxin content than shoots which developed after a low cut back.These findings are discussed in relation to the effect of temperature, light intensity and cut back practise on blind shoot formation in roses. The result of these investigations strongly indicate that abortion in roses is promoted by a low auxin level in the shoots.