bluuebunny/crossref_metadata_2025_split huggingface dataset:
Spring Mobilization of Storage Nitrogen in Isolated Shoot Section of Apple
Authors: TROMP J. , OVAA J. C. 
Published: April 2006

AbstractThe process of mobilization of nitrogenous compounds in trees during spring development was studied in short isolated shoot sections (usually bearing one bud each) of Golden Delicious apple trees. During leafing‐out of the bud, changes in the amounts of total, protein and soluble nitrogen and of soluble amino acids and amides in bark and wood were followed. The nitrogen required by the growing parts came mainly from protein breakdown in the tissues below the bud; in the tissues above the bud, total nitrogen decreased little, whereas the drop in protein nitrogen was considerable. In de‐budded sections and in internode sections where total nitrogen remained almost unchanged, protein hydrolysis occurred as well. It is concluded that the protein breakdown is not strongly dependent on the demand of the bud for nitrogen.Inversion of the sections did not result in any change in the pattern of nitrogen mobilization: a marked drop occurred in the nitrogen content of the physiologically basal part of the section and only a slight decrease in the apical part. The translocation of stored nitrogenous compounds to the growing parts seems to occur in the phloem, at least over short distances.Asparagine and arginine were found to be the major components of the soluble amino‐nitrogen fraction throughout. The relative importance of asparagine was reduced in tissue where a substantial loss of nitrogen occurred during leafing‐out of the bud. This is explained in terms of a preferential export of asparagine to the bud.
Abscisic Acid Action on Basipetal Auxin Transport
Authors: PILET P. E. 
Published: April 2006

AbstractSeveral experiments have been performed to analyse the ABA effects on the basipetal transport of IAA‐2‐14C, using sections of epicotyls prepared from etiolated Lens seedlings. The sections were incubated in an ABA solution or ABA was applied in the donor blocks containing IAA. For each type of assay, the uptake (analyses of the donor blocks) and the movement of IAA‐C14 (analyses of the receiver blocks) were inhibited by ABA. The distribution of continuous decrease of the radioactivity, along the sections' axis, showed a 14C level from the apical towards the basal segments. ABA caused a decrease in the 14C concentration for the total sections, but a relative increase for the basal segment. When ABA was applied simultaneously with IAA in the donor blocks, the transport velocity of IAA, through the sections, was not changed significantly, while an ABA pretreatment caused a significant decrease.
Investigations of the Geotropic Curvature of the Avena Coleoptile
Authors: JOHNSSON A. , RENGMAN K. , GRAHM L. 
Published: April 2006

AbstractThe geotropic presentation time was studied in Avena coleoptiles as a function of the distance from the tip. Curvatures of decapitated plants, allowed to curve in IAA‐solutions, were recorded. Extrapolated values of the presentation times are roughly the same (about 4 min) in coleoptiles from which 1, 3, or 5 mm, respectively, of the tip have been removed by decapitation. Presentation times reported in the literature are generally longer and are stated to increase considerably with the length of the portion of the tip removed by decapitation. No such relationship was found in the present study. The discrepancies can, at least to a large extent, be explained by differences in principles and methods of measurement.The present results are in accord with measurements on the geoelectric effect in coleoptiles.
Photosynthetic Action Spectra of Scots Pine Needles of Different Ages from Seedlings Grown under Different Nursery Conditions
Authors: LINDER SUNE 
Published: April 2006

AbstractPhotosynthetic action spectra of pine needles have been measured with an automatic recording method. A thin longitudinal cut from the flat surface of the needle was placed on top of an oxygen sensor and illuminated with monochromatic light in the range 400–700 nm. Good correspondence between absorption and action spectra was obtained in the range 550–700 nm. In the blue part of the spectrum photosynthetic efficiency was low compared with absorption. This low effect in blue light is probably due to screening absorption by photosynthetically inactive carotenoids.One‐year‐old needles showed a higher effect in the blue part of the spectrum than did current year needles. Needles from seedlings grown in the open had a lower photosynthetic effect in the blue part than needles from seedlings grown in a greenhouse. Pigment analyses support the idea that these differences are due to differences in the ratio chlorophylls/total carotenoids and/or differences in the composition of the carotenoid pigments.
Causes of Centrifugal Root Promotion
Authors: KAWASE MAKOTO 
Published: April 2006

AbstractRole of water in centrifugal root promotion, effect of centrifugation on ethylene concentration of cuttings, and effect of ethylene on root formation were investigated using Salix jragilis softwood cuttings.When cuttings were centrifuged with water, more roots formed with increasing water depth. Soaking of cuttings upright in water for 24 h stimulated root formation and produced more roots as the depth of water was increased, with submerged cuttings producing the highest number of roots. Soaking of cuttings upright in hot water for 1 h also stimulated root formation with the best root formation occurring at 40°C. Submerging in, or centrifuging with water increased ethylene concentration in cuttings. Ethylene gas and Ethrel treatments stimulated root formation. It is suggested that submerging in water increases the ethylene concentration in Salix fragilis softwood cuttings which in turn stimulates root formation of the cuttings.Centrifuging cuttings with water increased water content of the cuttings. It is suggested that this increase in water content plays a role similar to the submersion of cuttings as described above.
Changes in Phosphorus Fractions and Phytase Activity of Rice Seeds during Germination
Authors: MUKHERJI S. , DEY B. , PAUL A. K. , SIRCAR S. M. 
Published: April 2006

AbstractThe present experiment provides information on the phosphorus compounds in rice seeds and elucidates the changes they undergo during germination. In ungerminated seeds, the bulk of total‐P appears in phytin (about 76 per cent). It is then dephosphorylated in course of germination with a simultaneous accumulation of large amounts of inorganic‐P. Lipid‐P increases very rapidly from 0 to 24 hours. The increase up to 72 hours is gradual, after which it drops at 96 hours and again rises to a maximum after 120 hours. The ester‐P and RNA‐P, fractions increase in concentration with time of germination (except 120 hours). Protein‐P begins to fall after 48 hours, while DNA‐P remains more or less constant throughout the experiment.The two pH optima recorded for phytase activity at 4.0 and 9.0, suggests that there exist two phytases, one acidic and the other alkaline. Both behave similarly during germination with a continuous increase throughout the course of the experiment. The enzyme with an optimal pH at 4 hydrolyses phytin more actively than the other with the pH optimum at 9.0. Phytase shows maximum activity at a stage when most of the phytin has disappeared; the metabolic significance is uncertain.
NAD‐ and NADP‐Linked Glyceraldehyde‐3‐Phosphate Dehydrogenases in Light‐ and Dark‐Germinated Seeds of Scots Pine (Pinus silvestris)
Authors: NYMAN BENGT 
Published: April 2006

AbstractBy means of arsenate in optical tests the occurrence of both NAD‐ and NADP‐linked glyceraldehyde‐3‐phosphate dehydrogenase activity has been found in embryo and endosperm tissues from Scots pine seeds. By exclusion of arsenate also evidences for the activity of a non‐phosphorylating NADP‐linked form have been demonstrated. The results are sustained by inhibition experiments. The enzyme activities have been followed principally during the first 24 hours of the germination process and in relation to the germination‐controlling light factor. Homogenates from complete seeds and partly also from separated embryo and endosperm tissues have been studied. The predominant activity in both of the tissues was linked to the NAD‐form, expressed either on seed (part) or protein basis. No indications for a light‐regulation of anyone of these enzymes have been found contrary to findings from other plant materials.
Aromatic Substances in Leaves of Populus tremula as Inhibitors of Mycorrhizal Fungi
Authors: OLSEN ROLF A. , ODHAM GÖRAN , LINDEBERG GÖSTA 
Published: April 2006

AbstractThe inhibitory principles of aqueous extracts of aspen leaves, acting upon mycorrhizal fungi of forest trees, were isolated by extraction with ethyl acetate and chromatography on silicic acid. Two inhibitors were identified as benzoic acid and catechol by gas chromatography and mass spectrometry. When added to a synthetic medium, these substances had a strong inhibitory effect on the growth of different Boletus‐species and a weaker inhibitory effect on litter‐decomposing Marasmius‐species. When the fraction of the extract which was not soluble in ethyl acetate was included in the medium, the aromatic compounds still inhibited the mycorrhizal fungi while the growth of the litter‐decomposers was stimulated.
Crystalline Ferredoxin from a Blue‐Green Alga, Nostoc sp.
Authors: MITSUI AKIRA , ARNON DANIEL I. 
Published: April 2006

AbstractFerredoxin isolated from a blue‐green alga, Nostoc sp., was purified and crystallized. The absorption spectrum of Nostoc ferredoxin had, in the oxidized state, peaks at 276, 331, 423, and 470 nm, a pattern characteristic of chloroplast‐type ferredoxin. The 423:276 absorption ratio was 0.57. The midpoint oxidation‐reduction potential of Nostoc ferredoxin was found to be –406 mV, at pH 7.5. Nostoc ferredoxin mediated the photoreduction of NADP by isolated Nostoc chromato‐phores and spinach chloroplasts from which the native ferredoxin was removed. The molar ratio of Nostoc ferredoxin to chlorophyll a was about 1:50, a ratio higher than usually found in photosynthetic cells.The possible evolutionary significance of the properties of Nostoc ferredoxin compared with those of ferredoxins from other photosynthetic organisms is discussed.
The Influence of n‐Propanol on the Growth and Conidiation of Pestalotia rhododendri
Authors: NORRMAN JONAS 
Published: April 2006

Abstract Pestalotia rhododendri was exposed to vapours from 1 ml propanol solution in water and linear growth, formation of aerial hyphae and production of conidia were determined. A special Petri dish technique was used and maximum stimulation of conidial formation was induced by the vapours from a propanol concentration of 3–4 % (v/v) at 25°C. When propanol was added directly to the medium, a concentration of 1.2 × 10−2M was optimal for growth and sporulation at 30°C.Sporulation stimulated by propanol was observed at temperatures from 20–32°C, with an optimum at 30°C. Certain observations indicated that an exposure to propanol for 24 hours was enough to induce a stimulated spore production. The stimulation was noticed on different media at 25°C, and was more pronounced at 30°C. One exception was observed. Propanol did not promote sporulation when the fungus was grown on maltagar at 30°C.Propanol 3 ° (v/v) in combination with the standard medium containing (NH4)2‐tartrate as sole nitrogen source, inhibited the linear growth at 15–20°C, was inactive at 22.5° and 25°C, and stimulated growth at 27.5–31°C. The stimulatory effect was maximal at 30°C. Other media were tested at 25° and 30°C. At both temperatures stimulations of linear growth caused by propanol were observed with a medium containing KNO3 as sole nitrogen source, and inhibitions with maltagar and another medium containing l‐asparaginc as sole nitrogen source. The linear growth could be either inhibited or stimulated while the sporulation was stimulated.
Nodulation in Sesbania aculeata as Affected by Some Pyrimidine Bases and Their Analogues
Authors: MATHUR S. N. , SINGH H. S. 
Published: April 2006

AbstractEffects of uracil, thymine and their analogues, 5‐nitrouracil, 2‐thiouracil, 6‐azauracil, and 6‐azathymine on nodulation in Sesbania aculeata have been studied. The seeds were dipped partially in a 15 ml solution of each of different concentrations. The experiments included treatments for 6 or 12 h with distilled water as control. The treated seeds were inoculated with a pure culture of Rhizobium leguminosarum and sown in sand cultures, weekly supplied with modified White's basic N‐free solution.Nodulation in Sesbania aculeata was promoted by uracil, nitrouracil and thymine, but inhibited by analogues. Higher concentrations caused greater inhibition than lower ones. Nodulation was affected by changes in the nucleic acid and protein metabolisms.
Effects of Hydroxyurea and Deoxyadenosine on the Synthesis of Deoxycytidine Phosphate and on the Uptake of Nucleosides in Excised Root Tips of Vicia faba
Authors: ODMARK GÖRAN 
Published: April 2006

AbstractThe effects of hydroxyurea and deoxyadenosine on the synthesis of deoxycytidine phosphate was studied by measuring the incorporation of [14C]‐cytidine into acid soluble deoxycytidine phosphate in root tips of Vicia faba. Hydroxyurea and deoxyadenosine both markedly depressed the incorporation of [14C]‐cytidine.Deoxyadenosine had the additional effect of inhibiting the uptake of [14C]‐cytidine. Furthermore, millimolar concentrations of deoxyadenosine inhibited the uptake of micromolar concentrations of adenosine, thymidine, and deoxycytidine.The incorporation of [14C]‐cytidine into RNA was only slightly affected by hydroxyurea. Deoxyadenosine inhibited the incorporation into RNA to about the same extent as the uptake of [14C]‐cytidine.It is suggested that hydroxyurea reduced the incorporation of radioactive cytidine into deoxycytidine phosphate mainly by interfering with ribonucleotide reduction. The depression of [14C]‐cytidine incorporation into deoxycytidine phosphate in the presence of deoxyadenosine is believed to be the result of an inhibition of both ribonucleotide reduction and [14C]‐cytidine uptake.
The Effect of Boron and Gibberellic Acid on the Senescence of Leaf Discs from Lycopersicon esculentum cv. Rutgers
Authors: PARMAR AMAR S. , HAMMOND H. DAVID 
Published: April 2006

AbstractWhen leaf discs of Lycopersicon esculentum Mill. cv. Rutgers were floated on solutions containing 4.33 × 10–6 M gibberellic acid (GA3), 1.0 ×x 10–6M boron (B), separately and together, senescence was retarded with respect to controls. Degradation of chlorophyll, total protein, RNA, and DNA was delayed, and decreases in fresh weight and leaf disc diameter checked. The loss of chlorophyll, protein, RNA, DNA, fresh weight, and diameter were 10, 20, 30, 8, 28, and 0 per cent with GA3 alone; 15, 25, 35, 8, 31, and 0 per cent with B alone; 8, 14, 25, 7, 25, and 0 per cent with GA3 plus B; contrasted with 50, 40, 50, 9, 42, and 3 per cent for the controls. An analysis of variance was performed on all data except for disc diameter. All sources of variance were significantly or highly significant at the 1 per cent level except for the effect of boron on DNA level, which was significant only at the 2.5 per cent level. Retardation of senescence by GA3 may be associated with the known ability of GA3 to stimulate m‐RNA and protein synthesis. The effect of boron may be due to an effect on sugar and starch balance, translocation of sugar, or on water balance, but more likely boron plays a role in nucleotide and protein metabolism in plants. Boron may be involved in the synthesis of DNA, a role perhaps mediated by GA3.
Crown Gall Development Stimulated by Wound Washing
Authors: THERMAN EEVA , KUPILA‐AHVENNIEMI SIRKKA 
Published: April 2006

AbstractA number of experiments on the effect of wound washing on the development of crown gall were made varying the following factors: Host species; bacterial strain; non‐washing versus washing for different periods; sterile versus inoculated wound; time of inoculation. Washing did not have a recognizable effect on the healing of sterile wounds. Neither did it seem to overcome incompatibility between host and bacterial strain. Washing promoted tumor growth significantly under the following conditions: Vicia faba inoculated with T37 20 hours after washing for 1 hour; Helianthus annuus inoculated with B6 immediately after washing for 2 hours.
Strontium‐substitution for Calcium and Algal Cell Size
Authors: MOSS SAMUEL W. , THOMAS JERRY P. , O'KELLEY JOSEPH C. 
Published: April 2006

AbstractMature cells of several algal species (Protosiphon bo‐tryoides, Chlorococcum echinozygotum, Asterococcus superbus, Chlamydomonas reinhardtii, Chlorella pyrenoidota) that will grow in a strontium‐substitution for calcium are larger and more highly vacuolated than control cells in calcium. In logarithmic phase cultures average cell size of cells in strontium‐replacement medium is greater than for control cells in calcium. The water content of strontium‐replacement cells is indicated to be greater than of control cells. Mechanisms whereby water content and cell size differences may become established are discussed.
Changes in Pigment Composition and Photosynthesis Induced by Iron‐Deficiency in the Blue‐Green Alga Anacystis nidulans
Authors: ÖQUIST GUNNAR 
Published: April 2006

AbstractAbsorption spectra and photosynthetic action spectra have been determined for living Anacystis grown in complete and iron‐deficient inorganic media. The absorption studies have shown a spectral shift from 679 nm to 673 nm in the chlorophyll a absorption peak when the algae had to grow without iron. The shift is believed to reflect a changed ratio between at least two chlorophyll a forms denoted Ca670 and Ca680 in this work. Action spectra determinations have revealed a similar shift from 677 nm to 672 nm in the photosynthetic activity peak of chlorophyll a when Anacystis was transferred to a medium without iron. It is proposed that both Ca670 and Ca680 participate in light absorption for photo‐system I.
Radial Oxygen Losses from Intact Rice Roots as Affected by Distance from the Apex, Respiration and Waterlogging
Authors: ARMSTRONG W. 
Published: April 2006

AbstractRadial oxygen losses (ROL) from the roots of intact rice plants were assayed by the cylindrical Pt electrode technique.At 23°C losses from roots grown in waterlogged soil proved to be about double those from non‐waterlogged plants.Cooling which lowers respiratory activity led to increased ROL and it was estimated that at 23°C respiratory activity had been reducing oxygen loss by 8 to 10 10–8g O2 cm–2 root surface min–1 (c. 50 %) in the non waterlogged, and by 4.5 to 5.5 10–8g O2 cm–2 min–1 (2C–30 %) in the waterlogged roots.Lacunae formation occurred nearer to the apex and was eventually more extensive in the waterlogged roots while the presence of more intact and presumably functional tissue in the non‐waterlogged roots coincides with the greater respiratory effect noted.Estimated flux rates at 23°C (respiration inactive) were respectively 15–17 × 10–8g O2 cm–2 min–1 (non‐waterlogged) and 20–23 × 10–8g O2 cm–2 min–1 (waterlogged). A major part of this difference can probably be accounted for directly by the differences in root porosity, and Meakiness' superimposed upon lower porosity in the non‐waterlogged plants may account for the remainder.ROL was also examined in relation to distance from the apex. With respiratory activity lowered by cooling, two patterns of oxygen loss were detected. Pattern I was a property of younger roots of length between 5–9 cm, while pattern 2 was found in longer roots 11–16 cm bearing numerous emergent laterals. In both, ROL fell rapidly towards the base and at 4–5 cm approached zero in pattern 1 and near zero to about 16% of the maximum in pattern 2.The rapid drop in oxygen loss in both patterns which indicates a concomitant decrease in root wall permeability was associated with the appearance of cortical lacunae at 2–3 cm from the apex.In pattern 2 a rise in ROL began at 5–6 cm from the apex. The presence of lateral root initials in both the pericycle and unbroken segments of cortex was associated with maintained permeability in this pattern as well as with the basal increase in ROL.With a 3‐electrode system placed around the apical 3 cm regions of waterlogged roots, it was found that ROL was substantially affected by respiratory activity at 0.5 cm, a little less so at 1.7 cm, but much less or not at all at 3 cm from the apex. The drop in respiratory effect parallelled the formation of cortical lacunae.
Calcium and Salt Toleration by Bean Plants
Authors: LAHAYE PHILIP A. , EPSTEIN EMANUEL 
Published: April 2006

AbstractThe role of calcium in the salt relations of the bean plant, Phaseolus vulgaris, was examined. Brittle wax bush bean plants were cultured in nutrient solutions containing 50 mM NaCl. In the absence of added calcium the plants showed a general breakdown of the roots. A low concentration of calcium in the nutrient solution (0.1 mM) prevented this. Without added calcium the plants absorbed and translocated sodium at such a rate that high concentrations of it built up in the leaves within two days. With increasing concentrations of calcium in the nutrient solution the leaves contained progressively less sodium, and at 3 mM CaSO4 the concentrations of sodium in the leaves was equal to that of the control plants grown without addition of salt. Even after both roots and stems had reached a high concentration of sodium, the leaves of plants grown in the presence of adequate concentrations of calcium contained little sodium.
Evidence for Hormonal Regulation of the Selectivity of Ion Uptake by Plant Cells
Authors: ILAN I. 
Published: April 2006

AbstractKinetin exerted opposing effects on the uptake of K+ and of Na+ by leaf discs of Helianthus annuus: The absorption of K+ was stimulated and that of Na+ was inhibited. The K+/Na+ ratio in kinetin‐treated discs was 80–100 % higher than in control tissue.Kinetin also promoted K+ uptake by detached cotyledons which had been removed from light‐grown seedlings. On the other hand, no clear effect on the absorption of Na+ by these cotyledons could be established.Benzyladenine brought about a significant elevation in the K+/Na+ ratio in attached cotyledons.It is concluded that cytokinins bring about a change in the selectivity of the cells of sunflower leaves and cotyledons towards K+ and Na+, such that the ‘affinity’ of the cells for pottasium is increased, as compared to the ‘affinity’ for sodium. The possible significance of such a change in selectivity is discussed.
α‐Glucosidase Activity Located at the Cell Surface in Callus of Convolvulus arvensis
Authors: KLIS F. M. 
Published: April 2006

AbstractCell wall preparations of Convolvulus callus were found to contain α‐glucosidase activity, the bulk of which could be solubilized by solutions of high ionic strength. Callus tissue incubated in 0.5 M KC1 released α‐glucosidase activity into the washing medium as distinct from tissue incubated in 1.0 M sorbitol. The wall‐bound activity of KCl‐treated tissue was found to be less than that of sorbitol‐treated tissue, while the difference between both activities proved to be equal to the enzyme activity found in the washing medium of KCl‐treated tissue. Since no trace of cell leakage was observed, it is concluded that α‐glucosidase activity is located at the cell surface. The level of this surface‐located enzyme was not affected by the presence of maltose in the nutrient medium.