bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Role of Cytokinin in the Regulation of Growth, DNA Synthesis and Cell Proliferation in Cultured Soybean Tissues (Glycine max var. Biloxi)
Authors: FOSKET D. E. , SHORT K. C. 
Published: April 2006

AbstractChanges in protein content and cell proliferative activity were followed after a cytokinin‐requiring strain of cultured Glycine max tissue was transferred to freshly prepared media which either contained or lacked cytokinin. Cell numbers doubled within the first two days after transfer, both in the presence and absence of cytokinin. However, after the second day no further increase in cell number was observed in the absence of cytokinin, while cell numbers continued to increase logarithmically in the presence of cytokinin. The size of the cell population attained after the first six days of growth was a function of the cytokinin concentration of the culture medium. However, the amount of 3H‐thymidine incorporated into nuclear DNA bore no relation to the rate of cell proliferation. Tissues cultured on medium lacking cytokinin incorporated the greatest amount of 3H‐thymidine per microgram of DNA, while the actively dividing tissues incorporated somewhat less. Using autoradiography and isopycnic CsCl gradient centrifugation, it was shown that the radioactivity derived from 3H‐thymidine was associated with nuclear DNA in the cytokinin‐deprived cells. Biochemical measurements demonstrated that cells cultured for six days without cytokinin had approximately twice the DNA content of the actively proliferating cells cultured on cytokinin‐containing medium. Furthermore, in autoradiographs labeled cells were found to average nearly three times as many silver grains per nucleus in tissues cultured without cytokinin as the cytokinin‐grown tissues. This suggests that the 3H‐thymidine incorporation in the non‐proliferating soybean cells results from nuclear DNA synthesis and that some of the cells became polypoid in the absence of cytokinin. These findings would be consistent with the idea that cytokinin acts as a specific trigger for cytokinesis.
Oscillatory Transpiration and Water Uptake of Avena Plants I. Preliminary Observations
Authors: JOHNSSON ANDERS 
Published: April 2006

AbstractOscillations in transpiration and water uptake of individual, young oat plants have been studied. The free‐running period of these oscillations was about 30 minutes. Conditions were reached under which the oscillations were sustained for about two days.Short perturbations were given to the transpiration oscillations, the perturbations consisting of a short time increase or decrease in the illumination. The phase shifts of the oscillations as well as the amplitude effects caused by these perturbations were investigated.Simultaneous recordings of transpiration and water uptake of a single plant showed that these functions were oscillating in phase. Both oscillations disappeared if the leaf was excised.
Phytochrome et germination des semences de Rumex
Authors: BIANCO J. 
Published: April 2006

AbstractThe Rumex alpinus L. achenes show a special type of positive photosensitivity: several red light irradiations are necessary to induce optimal germination. The achenes deprived of their pericarp lose their photosensitivity and germinate readily in the dark. By spectrophotometry in vivo, the presence of the Pr form of phytochrome is revealed in these seeds.Short periods at extreme temperatures (30°C or 5°C) induce a good proportion of achenes to germinate. The gibberellins are inefficient on achene germination contrary to benzyladenine which exhibits some activity. A slight improvement of GA4 effects has been detected on scarified fruits.
Indole‐3‐Pyruvic Acid as an Intermediate in the Conversion of Tryptophan to Indole‐3‐Acetic Acid. II. Distribution of Tryptophan Transaminase Activity in Plants
Authors: TRUELSEN T. A. 
Published: April 2006

AbstractExtracts from different organs of 30 plant species belonging to 16 families have been analysed for tryptophan transaminase activity. Only the brown alga Fucus spiralis was found to be devoid of the enzymes. Among the other plants tested, a difference in activity of two orders of magnitude was recorded. None of the genera or families investigated could be considered as particularly rich or poor sources of the enzyme. Extracts from leaves and stem tips contained generally more transaminase activity than extracts from stems and roots. The results are discussed in relation to other reports on the occurrence of the enzyme in plants.
The Effect of Storage Temperature on Shoot Growth, Flowering, and Carbohydrate Metabolism in Tulip Bulbs
Authors: MOE ROAR , WICKSTRØm ALF 
Published: April 2006

AbstractDry bulbs of the cvs. ‘Apeldoorn’ and ‘Paul Richter’ at stage G of flower development were stored at 5° or 21°C for 2, 4, 6, 8, 10, 12, and 14 weeks, respectively before being planted and forced at 18°C. Samples from each treatment were taken for carbohydrate analysis.The low temperature treatment (5°C) was necessary to obtain satisfactory shoot growth and flowering after planting. The rate of shoot growth and the percentage of flowering bulbs increased with increasing duration of the 5°C treatment. Time of flowering was also precipitated. 12–14 weeks of low temperature treatment seemed optimal. High temperature (21°C), or a short period at 5°C (2–6 weeks), resulted in many non‐flowering bulbs, and a very slow shoot elongation when flowering occurred. In the latter case the tips or large areas of the perianths became white, the red pigmentation being prevented.Paper chromatographic analysis of oligosaccharides revealed a substantially increased content of sucrose and fructosyl sucrose (DP ≤ 5) during the first 2–4 weeks of cooling. At the end of 12 weeks at 5°C, the content of oligosaccharides decreased.The increase in the oligosaccharide content was accompanied by a corresponding starch decrease. High temperature storage (21°) led to comparatively slight changes in the sucrose and fructosyl sucrose content of the bulbs.The significance of carbohydrate metabolism in relation to shoot elongation and flowering is discussed.
Effects of Daylength on Endogenous Gibberellins in Leaves of Solanum andigena
Authors: RAILTON I. D. , WAREING P. F. 
Published: April 2006

AbstractLess gibberellin‐like activity was detected in extracts of potato leaves under short day than under long day conditions. Significant decreases in gibberellin levels were detected after two short day cycles. Using thin‐layer chromatography coupled with several solvent systems and various bioassays, at least four zones of gibberellin‐like activity, A, B, C and D were found in the potato leaf. Under long days only zones C and D were apparently present. However, preliminary purification using polyamide columns revealed that substances A and B were actually present in higher levels under long day than under short day conditions.The chloroplasts of leaves exposed to short days contained less gibberellin‐like substances than those from leaves grown under permanent long day conditions.
Kinetics of Ion Uptake in Higher Plants
Authors: NISSEN PER 
Published: April 2006

AbstractSingle, multiphasic mechanisms located in the plasmalemma and the tonoplast are proposed to mediate ion uptake in cells of higher plants. There are no parallel uptake mechanisms and, normally, little or no free diffusion across the plasmalemma. The plasmalemma controls the rate of uptake at low external salt concentrations, while the tonoplast may become rate‐limiting at high concentrations.
The Effect of Sodium and Calcium on the Translocation of 14C‐sucrose in Excised Cotton Roots
Authors: JOHAM H. E. , JOHANSON LAMAR 
Published: April 2006

AbstractThe effect of sodium and calcium on the translocation of 14C‐sucrose in excised cotton roots (Gossypium birsutum) was studied. The roots were allowed to elongate in a modified Guinn's medium that was very low in calcium (6.25 × 10−2 mM) and sodium (8.70 × 10−3 mM). After a period of six days the roots were transferred to 20 × 100 mm Petri dishes that contained 10 × 40 mm Petri dishes as center wells. The roots were draped over the edge of the center well and extended into the outer dish. The outer Petri dish and its center well contained the same solution except that sucrose was supplied only in the center well. The sucrose used was spiked with uniformally labeled 14C‐sucrose. Four treatments were started which varied in their Na and Ca content.Three and six day harvests were taken and the amount of 14C that had moved from the distal (in the center well) to the apical root section (in the outer dish) was determined. Increasing substrate Na or Ca caused an increase in 14C‐sucrose translocation and the effects of both ions were additive by the final harvest. These results were found to be independent of treatment effects on growth and respiration of the excised roots.These data support the conclusion that Na may partially substitute for Ca in carbohydrate translocation. Thus, roots supplied the Low Ca‐High Na and High Ca‐Low Na treatments had equal translocation rates over a six day period. The highest translocation rate was obtained with the High Ca‐High Na treatment. Data from the High Ca‐High Na treatment on two successive three day periods indicate that Na may have a role in translocation other than that associated with substitution for Ca, or maintenance of tissue hydration.
Shoot Differentiation in Callus Cultures of Datura innoxia
Authors: ENGVILD K. C. 
Published: April 2006

Abstract Datura innoxia Mill. callus cultures formed shoots in 2–4 weeks on media containing; a) gibberellic acid, b) indoleacetic acid, c) low concentrations of naphthylacetic acid, d) low concentrations of 2,4‐dichlorophenoxyacetic acid, e) benzylaminopurine, f) no growth substance.Benzylaminopurine promoted shoot differentiation. Gibberellic acid inhibited shoot formation weakly, but inhibited proper leaf blade formation.Root differentiation was rare.The callus cultures of Datura innoxia grew rapidly (100‐fold in 4 weeks) on a slightly modified Murashige and Skoog medium (0.5 mg/l thiamin · HCl, pH 5.5, no glycine) in light at 30°C. Callus grew well on any single one of the growth substances NAA (10−5M), 2,4‐D (10−6M) or BAP (3 × 10−6M). Growth was less and more erratic on GA or IAA. The callus cultures did not grow significantly better when BAP was combined with one of the auxins or with GA.
Isolement d'une alcool déshydrogénase chez Rhizobium et rôle dans le métabolisme indolique
Authors: RIGAUD JEAN , TRINCHANT JEAN‐CHARLES 
Published: April 2006

Abstract Rhizabium meliloti contains an alcohol dehydrogenase (E.C.1.1.1.1.) which can be isolated by breaking the cells. This soluble enzyme was purified 16.1‐fold by fractional precipitations with ammonium sulfate followed by gel filtration on Sephadex. The activity of the enzyme was tested with various aldehydes as substrates in the presence of NADH. Indole‐3‐acetaldehyde (IAAld) can be reduced to tryptophol (Tr‐ol), and the optimal pH for this reaction is ca. 6.5. The reaction can be reversed, and Tr‐ol is oxidised in the presence of NAD, but is was found that the yield was very poor; the optimal pH was ca. 8.6. This alcohol dehydrogenase is responsible for Tr‐ol formation in Rhizobium, but under our experimental conditions tryptophol cannot really be considered as a precursor of IAAld and indole‐3‐acetic acid.
Ethylene as a Cause of Transient Petiole Epinasty in Helianthus annuus during Clinostat Experiments
Authors: PALMER J. H. 
Published: April 2006

AbstractPetiole curvature and elongation growth in Helianthus annuus L. have been recorded for plants rotating with their stems parallel to the horizontal axis of a clinostat at 8 revolutions per hour over 72 hours. When rotation was continuous, dorso‐convex curvature (epinasty) developed in the first 12 hours and was followed by recovery (straightening) in the next 36 hours. Thereafter the petioles remained straight. These changes in shape are due to brief consecutive increases in the elongation growth of the upper and lower halves of the petiole. Plants exposed to 10 μl per liter ethylene after 200 hours on the clinostat, developed similar petiole epinasty, followed by straightening when the exposure to ethylene ceased. Interrupting rotation of the plant for 1 hour in 4, did not change the petiole response, whereas the alternation of 4 hour stationary and rotation periods, delayed the straightening process. The axillary angle between the stem and petiole increased from about 40° to 63° during either continuous rotation or rotation with 1 or 4 hour stationary periods. When detached leaves were inverted, the rate of ethylene release approximately doubled after 4 hours and continued to increase thereafter. The results indicate that the development of transient petiole epinasty on the clinostat, is due to ethylene production caused primarily by the disorientation of the plant, rather than to the rotation process.
Changes in Transpiration, Net Carbon Dioxide Assimilation and Leaf Water Potential Resulting from Application of Hydrostatic Pressure to Roots of Intact Pepper Plants
Authors: JANES B. E. , GEE G. W. 
Published: April 2006

AbstractHydrostatic pressures varying from 0 to 6.0 bar were applied to roots of intact Capsicum annuum L. cv. California Wonder plants growing in nutrient solution and the rates of transpiration, and net CO2 assimilation, apparent compensation point and leaf water potential measured.Increasing the pressure on the roots of plants with roots in solution with either ‐0.5 or ‐5.0 bar osmotic potential with 1 bar increments resulted in a decrease in transpiration. With the application of 1 or 2 bar pressure the rate of transpiration returned to near or above the original rate. An application of 3 or 4 bar pressure reduced the rate of transpiration of all plants. The transpiration of plants with roots in solution with ‐0.5 bar osmotic potential remained at the reduced rate for as long as these pressures were maintained. The transpiration of plants with roots in solution with ‐5.0 bar was only temporarily suppressed at these pressures. Changing the applied pressure from 3 or 4 bar to 0 resulted in a rapid increase in transpiration which lasted approximately 15 minutes. This was followed by a decrease in transpiration to a rate lower than before the pressure was applied. The pattern of response was similar for plants at low or high light intensity or at normal or low CO2 concentrations. When leaf diffusive resistance was 6.0 s cm−1 or greater, changes in net CO2 assimilation were similar to those of transpiration. The apparent CO2 compensation point increased as pressure was applied and decreased with a release in pressure. Leaf water potential increased with an increase in pressure and decreased with a decrease in pressure. The changes in leaf water potential were frequently but not always proportional to changes in pressure.It is postulated that the respouses noted were due to changes in resistance to flow of water from xylem terminals through the mesophyll cells and stomatal cavities to the atmosphere.
Effect of Potassium Supply on the Acropetal Transport of Water, Inorganic Ions and Amino Acids in Young Decapitated Sunflower Plants (Helianthus annuus)
Authors: MENGEL KONRAD , SIMIC RADOMIR 
Published: April 2006

AbstractThe effect of potassium supply on the exudation rate and the content of ions and amino acids in exudation sap was studied using young decapitated sunflower plants (Helianthus annuus L.). Plants were grown originally in a complete nutrient solution. After decapitation one set of plants was transferred to a nutrient solution without potassium and another set to a solution with potassium, all other nutrients remaining the same for both treatments.During an experimental period of 3 days the plants supplied with potassium showed exudation rates which were more than twice as high as plants in the nutrient medium without potassium. The potassium supply affected the potassium and nitrate contents of the exudation sap. Both were lower in the treatment without potassium. The calcium and magnesium contents of the exudation sap were not significantly influenced by the potassium treatment, whereas the phosphate content was higher in the treatment without potassium. At the beginning of the exudation period the potassium supply did not affect the content of amino acids in the exudate, but later the plants supplied with potassium showed higher contents of amino acids in the exudation sap.As the absence of potassium reduced the exudation rate considerably the acropetal transport of all exudation sap constituents analysed in this experiment was markedly reduced.
Effect of Certain Nucleic Acid and Protein Inhibitors on Carotenogenesis in Verticillium agaricinum
Authors: MUMMERY ROSEMARY S. , VALADON L. R. G. 
Published: April 2006

AbstractCycloheximide, actinomycin D, puromycin, 5‐fluorouracil and 5‐fluorodeoxyuridine, all inhibitors of nucleic acid and protein synthesis, have been used to investigate at which level light affects carotenogenesis. The first three compounds inhibited both total protein and total carotenoids whereas the other two inhibited protein but not carotenoids. The results suggest that ribosomal RNA or possibly AMP‐rich RNA must be implicated in the light effect.A scheme involving protein synthesis is proposed to account for the results obtained.
Carbon Dioxide and pH Requirements of Non‐Photosynthetic Tissue Culture Cells
Authors: NESIUS KNEELAND K. , FLETCHER JOHN S. 
Published: April 2006

AbstractMaximum growth of suspension cultures of Paul's Scarlet rose required a low pH (5.2 to 5.4) during the division phase (day 0 to 7) and a higher pH (5.8 to 6.0) during the expansion phase (day 7 to 14).The fresh weight increase was reduced by approximately 22%, but the dry weight was not influenced when cells were grown for 14 days in a CO2 deficient environment. Kinetic studies showed that the first five days of growth was the critical period of nonautotrophic CO2 fixation when cells were grown in medium buffered at pH 5.4. The phosphoenolpyruvate carboxylase activity was highest (0.50 × 106 cpm min−1· g−1 fresh weight) during the period when nonautotrophic CO2 fixation appeared to be critical for growth.
Studies on the Flowering Mechanism in Lemna
Authors: KHUDAIRI A. KARIM , MAENG JUESON 
Published: April 2006

AbstractThe dark reaction of the short day plant Lemna perpusilla was investigated. It was found that 3‐phosphoglycerate and pyruvate (10−6M) increased the flowering rate in the presence of nitrates. Pyruvate‐2‐14C was added to the culture solution during two hours of the dark reaction and 14C was incorporated into serine, aspartate and glutamate. It was postulated that pyruvate reacted with a nitrogen source forming an intermediate, possibly aspartate, which was further converted into serine. L. perpusilla failed to flower when the dark period was interrupted with red light and as a result endogenous serine accumulated in a high concentration. The dark reaction of L. perpusilla, in which serine was involved, required (1) oxygen, (2) ATP, (3) moderate temperature, and (4) an enzyme system.
Synchronous Cultures of Chlamydomonas reinhardti: Properties and Regulation of Repressible Phosphatases
Authors: LIEN TORLEIV , KNUTSEN GJERT 
Published: April 2006

Abstract De novo synthesis of phosphatase (derepression) in orthophosphate deprived synchronously growing Chlamydomonas reinhardti has been demonstrated by using a double labelling isotope technique coupled with cellulose acetate electrophoresis. Repressed and derepressed phosphatase exhibited different enzymatic properties as pH optimum, electrophoretic pattern, Km and Ki values. Especially the acid phosphatase was located near the cell surface.Inorganic, cold TCA‐extractable 32P, decreased during the first 1–2 h after phosphate deprivation when there was little or no net synthesis of phosphatase.Results of experiments with additions of orthophosphate and cycloheximide to derepressed cells, indicated that the derepressible enzyme was relatively unstable, while its m‐RNA was relatively stable.
Changes in Urease Activity in Apple Trees as Related to Urea Applications
Authors: SHIM KYUNG‐KU , SPLITTSTOESSER WALTER E. , TITUS JOHN S. 
Published: April 2006

AbstractChanges in urease (E.C.3.5.1.5.) were followed during the growth of 1‐year‐old MM 106 and 9‐year‐old Golden Delicious apple trees (Malus pumila Rehd.). Urease was found in leaves, roots, and bark with actively growing tissues containing more activity than senescing tissues. The urease activity in the leaves declined steadily during leaf senescence but abscised leaves still contained about half of their initial urease activity. In the bark the urease activity changed only slightly. Urease activities in the leaves and bark of apple trees were always greater in those trees which had received an application of urea. In senescing apple leaves, urea induced a rapid increase in urease activity. The changes in total activity and specific activity of urease were parallel and suggests that urease was synthesized de novo. After urease activity reached a maximum, a rapid decline occurred. Urease was inhibited by low concentrations of ammonia and this decline may be due to product inhibition.
Response of Cowpeas to Salinity and (2‐Chloroethyl) trimethyl‐ammonium Chloride (CCC)
Authors: IMBAMBA S. K. 
Published: April 2006

AbstractRecent investigations have demonstrated that the growth retardant, (2‐chloroethyl) trimethyl‐ammonium chloride (CCC) inhibits several aspects of vegetative growth. In solution culture experiments, reduction in plant growth and dry matter production was confirmed in cowpeas, Vigna unguiculata L, (cv. Makueni II), when treated with CCC. The growth retardant had negligible effect on the rate of transpiration per unit leaf area although it slightly increased the relative water content of leaves. Stomatal opening was suppressed by CCC treatment but the number of stomata per unit leaf area was increased by the growth retardant. Variations in mineral element content (K, Ca, N and Na) of shoots are presented and discussed in relation to CCC treatment.
The Influence of the Synthetic Growth Regulator α‐Chloro‐(β‐(3‐chloro‐o‐tolyl) propionitrile on Some Phytochrome‐mediated Processes
Authors: DIERICKX P. J. , VENDRIG J. C. 
Published: April 2006

AbstractIn intact Sinapis alba seedlings the synthetic growth regulator α‐chloro‐β‐(3‐chloro‐o‐tolyl)propionitrile (PRB‐8) inhibits the phytochrome‐mediated anthocyanin synthesis, carotenoid synthesis and L‐phenylalanine ammonia‐lyase activity. This action was compared with that of other auxins and with that of α‐chloro‐β‐(3‐chloro‐o‐tolyl)propionitrile‐homologues. From the results it appeared that PRB‐8 and some other o‐tolyl derivatives are more inhibitive than other known auxins.
Triterpeneglycosides as Inhibitors of Fungal Growth and Metabolism 6. The Effect of Aescin on Fungi with Reduced Sterol Contents
Authors: OLSEN ROLF A. 
Published: April 2006

AbstractThe amount of sterols in the mycelia of Ophiobolus gra‐minis and Neurospora crassa was reduced by cultivating the fungi in the presence of inhibitors of the sterol synthesis. The hypocholesteraemic compounds β‐diethylaminoethyl‐(2.2‐diphenylpentanoate) hydrochloride (SK & F 525‐A) and 2.2‐diphenyl ‐1 ‐(β‐ dimethylaminoethoxy)pentane hydrocchloride (SK & F 3301‐A) were particularly effective in reducing the sterol contents. At the same time, the growth yield was reduced. Aescin had a reduced inhibitory effect on the radial growth of the mycelia with decreased sterol contents, the leakage of UV‐absorbing substances and K+ ions was reduced to small amounts, and the inhibition of the K+ uptake was nullified.