bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of Canavanine on Arginine Utilization in Plants with Special Reference to Mitotic Activity
Authors: WEAKS T. E. 
Published: April 2006

AbstractExcised primary roots ofPhaseolus vulgarisL. were treated with canavanine and the effect on arginine utilization was studied. Arginine utilization was observed to be depressed to a low level by canavanine (1.8 × 10−4M) in rapidly dividing and growing tissues. In addition, canavanine inhibited arginine utilization to a lesser degree in root sections composed of mature and non‐dividing tissues. This demonstrated that canavanine inhibition is not limited to those tissues where active DNA synthesis occurs.Canavanine was observed to inhibit the onset of mitosis in primary roots as evidenced by a significant reduction of the frequency of mitotic figures. In addition, this amino acid was found to affect the course of mitosis once it was initiated by altering the relative frequency of mitotic stages, decreasing the percentage of prophase figures and increasing the percentage observed in the telophase. An influence on the rate of spiralization and despiralization of the chromosomes is suggested. The effects on mitosis are probably related to growth‐inhibitory and toxic effects of canavanine. The possible function of canavine as an allelopathic substance is hypothesized.
Promoting Effect of Fusicoccin on Seed Germination
Authors: LADO PIERA , RASI‐CALDONGO FRANCA , COLOMBO ROBERTA 
Published: April 2006

AbstractThe effects of fusicoccin on the germination of dormant, light‐requiring or abscisic acid‐inhibited seeds has been investigated.(1) Fusicoccin (10−6M) induces germination in dormant wheat seeds (Triticum durum cv. Cappelli; 1972 crop) and stimulates it in seeds already relieved from dormancy (1971 crop), with an effect similar to that of gibberellic acid.(2) Fusicoccin (1.5 × 10−6M) is more active than the two phytohormones gibberellic acid and benzyladenine and than white light in stimulating light‐requiring lettuce seeds (Lactuca sativa cv. Grand Rapids) to germinate. Germination of radish seeds (Raphanus sativus) is also accelerated by fusicoccin, while benzyladenine and gibberellic acid are less active in this material.(3) Fusicoccin (1.5 × 10−5M) removes almost completely the inhibitory effect of abscisic acid on germination of radish and lettuce seeds, whereas benzyladenine (10−4M) and gibberellic acid (3 × 10−4M) remove the inhibition only partially.The possible relationship between these results and previous information on growth by cell enlargement is discussed in terms of the mechanism of action of fusicoccin as compared with natural hormones.
The Effect of Light on the Composition of DNA‐dependent RNA Polymerases of Verticillium agaricinum
Authors: VALADON L. R. G. 
Published: April 2006

AbstractFour cellular RNA polymerases have been partially purified from cultures of Verticillium agaricinum using DEAE‐cellulose chromatography. Polymerases 1 and II are probably localised in the nucleolus and non‐nucleolar portion of the nucleus respectively, while III and IV are probably mitochondrial in origin. DNA stimulation and dependency on the four ribonucleoside triphosphates were shown to be characteristic of all four polymerases. The products of their activity were sensitive to ribonuclease digestion and to KOH hydrolysis. The time course study of all four polymerases showed a linear increase for 1 min followed by a plateau and a rapid decrease after 5 min.Illumination of 4‐day‐old cultures increases the activity of RNA polymerase I, II, and III while only that of I and III is increased in 7‐day cultures. There is a similar increase in the amount of carotenoids produced by 4‐ and 7‐day‐old illuminated cultures. It is tempting therefore to suggest that ribosomes or mitochondria or both may be implicated in light‐induced cartogenesis.
Embryo Dormancy in Seeds of Acer platanoides
Authors: PINFIELD N. J. , DAVIES H. V. , STOBART A. K. 
Published: April 2006

AbstractOn dispersal the seed of Acer platanoides contained a dormant embryo, from which dormancy could be removed by chilling but not by hormone application. Dormany was deep in the embryonic axis, particularly in the radicle, but less so in the cotyledons. Under the storage conditions employed the dormancy pattern was modified so that during the subsequent incubation at 20°C, cotyledon expansion of isolated embryos from stored fruits was more rapid than that of isolated embryos from newly dispersed fruits. In addition, the dormancy of isolated embryos from fruits stored for several weeks could be broken by incubation in kinetin. It was concluded that embryo dormany in this seed can be divided into two phases, an initial phase when the embryo responds to chilling but not to cytokinins, and a later phase when cytokinins also become effective. The relationship between this transition and the apparent gradual reduction in the depth of embryo dormancy during storage is also discussed.The chilling period necessary for dormancy breaking was reduced by kinetin and to a lesser extent by gibberellin, indicating a close relationship between the concentrations of these hormones and the chilling requirement.
A Kinetic Theory of First Order Cyclical Processes—Phytochrome Controlled Red Light Induced Cereal Leaf Unfolding Compared with Theory
Authors: DEUTCH BENTE , DEUTCH BERNHARD I. 
Published: April 2006

AbstractThe phytochrome controlled unfolding of cereal leaves was studied as a function of irradiation time and light intensity (narrowband red light) over a wide energy range (5 decades). With different intensities, a family of similarly shaped response curves appear with distinct time‐dependent maxima and minima. A theoretical kinetic model based upon a cyclical phytochrome photoconversion scheme has been calculated by us. The theoretical calculations and the experimental findings are in excellent agreement. The same model explains the early photoresponses (first maxima) as an effect of one active phytochrome form, P2, and the delayed photoresponses as an effect of a second active form Pn. The active transitory form, P2 (although it may not be the primary product), is formed upon light absorption from P1. The P2 decays by a first order dark reaction through several inactive intermediates to Pn (active). The effect of the intermediates is mainly to delay the production of the second active product. It is possible to identify the two active products, P2 and Pn, as Pfr and P*fr, respectively.The presented cyclical phytochrome reaction scheme is a special case of a general first order kinetic cycle which includes all possible feed back loops. The latter scheme also has been calculated and programmed since it has a more general application.
The Effect of Chromium on the Photosynthesis and Growth of Diatoms and Green Algae
Authors: WIUM‐ANDERSEN SØREN 
Published: April 2006

AbstractThe effect of hexavalent chromium ions on the photosynthesis and growth of the diatom Nitzschia palea and the green alga Chlorella pyrenoidosa has been studied and compared with the effect of Cu and Hg. The effect of chromium is very similar to that of Cu and Hg, but it is more than one hundred times less toxic for the algae than copper. The toxicity of chromium is not counteracted by adding Fe to the culture solution. The problems regarding cleaning glass‐ware in dichromate‐sulphuric acid are discussed and it is strongly recommended to use other cleaning agents.
Protein Electrophoretic Pattern of Two Chlorella Mutants with Low and High Content of Sulphur‐Amino Acids
Authors: PASSERA CALVINO 
Published: April 2006

AbstractTwo mutants of Chlorella vulgaris characterized by high (HS) or low (LS) content of sulphur‐amino acids were compared to the wild strain with respect to their protein electrophoretic pattern.Three new bands, not present in the LS and wild strains, were found in the HS mutant. In algae grown in the presence of 35S labelled sulphate two of these new bands showed a very high 35S specific activity. Some electrophoretic bands common to LS, HS, and wild strain, were present in different proportions and showed different levels of specific radioactivity for each strain. Therefore, mutational events appear to have affected both the amino acid composition of single proteins and the relative amount of proteins with high and low sulphate content.
Hétérogénéité de la Germination des Semences de Rumex crispus mise en Evidence et Essai d'Interprétation
Authors: LE DEUNFF Y. 
Published: April 2006

Abstract Germination Heterogeneity of Rumex crispus L. seeds: Occurrence and Attempt at Interpretation. Rumex crispus L. seeds, harvested without taking into account localization of mother plants or seed position on single plants differ in their response to unfavourable conditions inductive of dormancy as a function of their weight. During induction, application of potassium or GA3 prevents or reduces the entry into dormancy, suggesting that the observed heterogeneity is due to nutritional variations of the seeds in relation to their position on the mother plant.
Transport of Abscisic Acid‐2‐C‐14 in Intact Pea Seedlings
Authors: BELLANDI DEISE MAURI , DÖRFFLING KARL 
Published: April 2006

AbstractWhen abscisic acid‐2‐C‐14 (AbA‐2‐C‐14), 1 μg in 5 μl 40% ethanol, is applied to the apical bud of light‐grown pea seedlings, C‐14 is translocated downwards only in very small amounts and does not enter the root. In contrast to this, C‐14 from indoleacetic acid‐C‐14 (IAA‐2‐C‐14) applied in the same manner is translocated to the root where it accumulates. When AbA‐2‐C‐14 is injected to the stem tissue at the apical bud, more labelled material is transported downwards than after application to the surface. Application of AbA‐2‐C‐14 to an expanded leaf results in considerable accumulation of C‐14 in the growing apical parts and in the lateral roots.
Variation du Taux d'Acide Chlorogénique dans les Bourgeons Végétatifs du Poirier au Cours de la Dormance Par
Authors: MELIN C. , BILLOT J. , DUPIN J. F. , PAULET P. 
Published: April 2006

AbstractA spectrophotometric technique after paper chromatography was found adequate for quantitatively determining chlorogenic and caffeic acids in the vegetative apical buds of Pyrus communis L., variety ‘Passe‐Crassane’, de ľOrléanais. Using this method, significant changes in these polyphenols were shown to occur both in tissue concentration and total amount per bud, in samples collected during winter 1973–1974. A close relationship between chlorogenic acid concentration and state of dormancy of excised twigs was found.
Growth and Plating of Cell Suspension Cultures of Datura innoxia
Authors: ENGVILD K. C. 
Published: April 2006

AbstractSuspension cultures of Datura innoxia Mill, were successfully grown on a modified Murashige and Skoog medium with 2,4–D, NAA or BAP as growth substances, provided the micronutrient levels were reduced to 1/10. Normal amounts of micronutrients were toxic. Attempts to identify the toxic elements did not succeed.Cultures grew exponentially on a shaker at 27°C in the light. Their doubling times varied from 1.1 days on 2,4–D (10–6M) or NAA (10−5M)+ 1 g/1 casein hydrolysate to 2.7 days on BAP (3 × 10−7M) and 5.1 days on supraoptimal levels of 2,4‐D (10−5M). Cultures grew on NH4+‐N alone (from ammonium malate) or on NO3−‐N alone. Dry weight yield was proportional to the amount of nitrate‐N added (47 mg/mg N).Filtered suspension cultures containing single cells (plating cultures) could be grown in agar in petri dishes when NAA or 2,4‐D were used as growth substances. Cells grew at densities above 500 units/ml in the agar. Most colonies grew from cell aggregates but division in single cells was observed. The highest plating efficiency was about 50% on 10−6 M 2,4‐D + 1 g/1 casein hydrolysate.
Lactate Dehydrogenase from Rhizobium. Purification and Role in Indole Metabolism
Authors: TRINCHANT JEAN‐CHARLES , RIGAUD JEAN 
Published: April 2006

AbstractCell‐free extracts of Rhizobium meliloti contain a soluble lactate dehydrogenase (LDH‐EC 1.1.1.27.). This was purified 250‐fold by ammonium sulfate precipitation and filtration on different Sephadex gels. This enzyme catalyses the reduction of pyruvate to lactate in the presence of NADH and for the first time we report its ability to reduce indole‐3‐pyruvic acid (IPyA) to indole‐3‐lactic acid (ILA). Optimal conditions for activity and Km values for both substrates were determined. In the presence of NAD the reverse reaction could be demonstrated with the aliphatic substrate (lactate), but under our conditions it was not possible to achieve the oxidation of ILA to IPyA. The role of this LDH in the indole metabolism is discussed and a general reaction scheme is suggested.
Photophysiology of Kalanchoë Seed Germination
Authors: ELDABH R. , FREDERICQ H. , MATON J. , DE GREEF J. 
Published: April 2006

AbstractGermination of Kalanchoé blossfeldiana seeds is absolutely light‐requiring and needs repeated daily light periods.With increasing length of the photoperiod there was a gradual escape from the far‐red inhibition. This escape depended also upon the duration of the far‐red exposure: 10‐second far‐red caused a strong inhibition after a 10‐ to 30‐minute photoperiod and did not inhibit after a 4‐hour day, although the effect of the latter was completely suppressed by 5 minutes far‐red. The action of a 12‐hour photoperiod was not reversed by 10 minutes far‐red but it was by 12 hours far‐red. Light intensity and temperature during the photoperiod were two other important factors influencing the escape from far‐red inhibition. The common features of this escape displayed in very different photomorphological responses are stressed.In order to explain our results in terms of phytochrome action, we distinguish two effects of white light:1) on the initial photoconversion of the inactive to the active PFR form2) on the much slower transformation of PFR to a reacted form P*FR; the latter reaction can also proceed in darkness, but is enhanced by light and is dependent upon light intensity and temperature; this reacted phytochrome is not reversible by a brief far‐red illumination.
Embryo Development in Ripe Seeds of Eranthis hiemalis and its Relation to Gibberellic Acid
Authors: FROST‐CHRISTENSEN HENNING 
Published: April 2006

AbstractThe ripe seeds of Eranthis hiemalis (L.) Salisb., the winter aconite, contain undeveloped embryos. At 20–25°C the embryos grow only little, and the seeds do not germinate. Rapid embryo development starts if the seeds, after 3 weeks of “after‐ripening” at 20–25°C, are placed at low temperature, 3–4°C; germination then takes place after 2–3 months, Embryo development without germination occurs when the seeds are placed in gibberellic acid solutions at 20–25°C. Embryo development is inhibited at low temperature by the specific inhibitor of gibberellin biosynthesis, 2‐chlorethyl cholin chloride, but is restored by the simultaneous addition of gibberellic acid. It is suggested that one early effect of the cold is to bring about a synthesis of gibberellin.
Ethylene and the Responses to Light of Rice Seedlings
Authors: MILLER JOHN H. , MILLER PAULINE M. 
Published: April 2006

AbstractThe growth of rice seedlings (Oryza satira L.) in the presence of ethylene caused a change in the response to light of coleoptile elongation. In plants grown in air without added ethylene coleoptile elongation was promoted by red, far‐red and yellow‐green light only in very young seedlings; in older plants irradiation inhibited the growth of the coleoptile. The effect of growing plants in the presence of ethylene was to prolong the period during which light promoted coleoptile growth. Elongation of the first internode was inhibited by light whether or not the seedlings were grown in the presence of ethylene. A correlation existed between the growth effect of an irradiation and the initial decay rate of phytochrome which was established by the treatment. Regardless of wave length, light sources whose intensities were adjusted to produce a decay rate of about 10% per hour or less induced a moderate rate of coleoptile elongation which persisted for a relatively long period. Irradiation with red or yellow‐green light of higher intensity which produced a higher rate of phytochrome decay induced a higher rate of coleoptile elongation, but growth stopped after several hours. Other observations, however, showed that one cannot establish a general simple correlation between the rate of elongation of rice coleoptiles under light and the status of measurable phytochrome in the plant.
Growth and Dormancy Cycles in Citrus Bud Cultures and Their Hormonal Control
Authors: ALTMAN ARIE , GOREN RAPHAEL 
Published: April 2006

AbstractAn in vitro bud culture method was devised in order to better understand the control mechanism of Citrus bud development. This technique offers a new approach to the study of hormonal control of growth, dormancy and flowering cycles in perennial plants.Buds were excised from orchard trees throughout the year, cultured on defined media for prolonged periods, and their vegetative growth responses to various growth hormones were determined. The buds proceeded with their vegetative development in vitro and achieved sprouting on a basal medium. The various growth regulators affected both the time required for sprouting (TRS) and the type of growth. In summer buds, IAA delayed sprouting, while GA enhanced it and caused shoot elongation. Cytokinins specifically induced the formation of numerous adventitious buds, whereas ABA completely inhibited sprouting; this inhibition, however, was reversible. A marked decrease in total protein and in the rate of its synthesis was evident during the first 20 days of sprouting induction and early bud growth.The annual growth rhythm was determined in spring buds sampled and cultured throughout the year, and an innate dormancy of citrus buds was revealed. Both the dormancy and the sprouting periods of buds in vitro corresponded to the natural periods occurring under field conditions. The effect of exogenous IAA, GA and cytokinins on the TRS varied at different periods along the season, suggesting the concept of “critical levels” in the endogenous balance of hormones.
Role of Silicon in Diatom Metabolism
Authors: MEHARD CHARLES W. , SULLIVAN C. W. , AZAM FAROOQ , VOLCANI B. E. 
Published: April 2006

AbstractThe in vivo uptake of 31Si‐silicic acid and 68Ge‐germanic acid by cell organelles of Nitzschia alba Lewin and Lewin and Cylindrotheca fusiformis Reimann and Lewin was demonstrated. The organelles were isolated by fractionation of pre‐labeled cells by differential centrifugation in 0.4 M sucrose medium. Electron micrographs showed that the isolated organelles were intact, with the exception of the N. alba mitochondria which appeared swollen and the C. fusiformis chloroplasts which had ruptured outer membranes and lacked stroma material. The amount of 31Si or 68Ge per mg protein of the subcellular fractions decreased in the following general order for both organisms: cell wall, mitochondria, chloroplasts, vesicles, and microsomes. A portion of the 31Si or 68Ge in the organelle fractions could be extracted into a distilled water wash. The uptake of silicon by the organelles suggests that silicon may be involved in some processes of the compartmentalized systems of the cell.
Sulfate Uptake and Respiration of Aging Potato Discs Modified by Malonic Acid and Ultraviolet Radiation
Authors: HANEBUTH WILLIAM F. , CHASSON ROBERT M. , PITTMAN DAVID 
Published: April 2006

AbstractThe time course of sulfate uptake in relation to respiration is shown for aging slices of potato, Solanum tuberosum L. cv. Russet. For comparative purposes, a time course for phosphate uptake is also shown. Malonic acid depressed both the respiratory rise and the sulfate accumulating ability of aging discs. A low dose of ultraviolet radiation given at the onset of aging reduced sulfate uptake by one‐half without lowering respiration. We hypothesize that sulfate uptake is controlled by at least two mechanisms: one associated with oxidative metabolism and the other mediated by protein synthesis.
Triterpeneglycosides as Inhibitors of Fungal Growth and Metabolism
Authors: OLSEN ROLF A. 
Published: April 2006

AbstractAescin in phosphate buffer reduced, to some extent, the production of 14CO2 from uniformly labelled glucose in mycelia of Ophiobolus graminis and Neurospora crassa, whereas aescin in succinate buffer had no effect. The enzymatic hydrolysis of sucrose was, however, severely affected, no production of 14CO2 from labelled sucrose being found after treatment of mycelia of O. graminis with 100 mg/l of aescin and N. crassa with 300 mg/l for 90 and 300 min, respectively. In Aspergillus niger the production of 14CO2 from glucose or sucrose was not affected. The ATPase in whole cells and isolated plasma membranes was not inhibited by the aescin treatment, on the contrary, the ATPase in whole cells of N. crassa was somewhat stimulated.
Lipids in Berseem Seed (Trifolium alexandrinum) during Germination as Affected by Gibberellic Acid and Maleic Hydrazide
Authors: BHATIA I. S. , SINGH I. P. , SUKHIJA P. S. 
Published: April 2006

AbstractLipid depletion of berseem seed treated with 100 mg/1 gibberellic acid or maleic hydrazide was studied during germination. During the first 3 days after germination there was little lipid consumption but thereafter the depletion of lipid was rapid. Gibberellic acid was found to enhance the lipid utilization of total lipids and triglyceride components during germination. On the other hand, maleic hydrazide reduced the utilization of triglycerides of the germinating seed. The rate of utilization was rapid for unsaturated fatty acids and slower for saturated ones in treated seeds as compared to untreated seeds.
Effect of Abscisic Acid on the Activities of Photosynthetic Enzymes and 14CO2 Fixation Products in Leaves of Pennisetum typhoides Seedlings
Authors: SANKHLA N. , HUBER W. 
Published: April 2006

AbstractAbscisic acid inhibited the rate of 14CO2 fixation in leaves of Pennisetum typhoides (Burm. f.) Stapf & Hubbard seedlings, but increased the activities of phosphoenol‐pyruvate‐carboxylase and malic enzyme. The leaves of the seedlings grown in the presence of abscisic acid incorporated, in comparison to the control, more radioactivity in the fraction of organic acids, but less radioactivity was recorded in the amino acid fraction. On the other hand, gibberellic acid which also inhibits photosynthetic 14CO2 assimilation and decreases the activities of photosynthetic enzymes, favours greater incorporation in alanine, and reduces that in malate. It is deduced that bio‐regulants can greatly influence the flow of 14C into individual photosynthetic products. As in growth, abscisic and gibberellic acids in combination tended to antagonize each other in their effects on enzyme activity as well as in incorporation of 14CO2 into photosynthetic products.
Indoleacetic Acid Oxidases in Resting Cereal Grains
Authors: LAUREMA SEPPO 
Published: April 2006

AbstractPeroxidases oxidizing indoleacetic acid (IAA) are present in the resting grains of barley, rye and wheat. The grains also contain small molecular inhibitors of the enzymes. A partly purified preparation of barley seed proteins was shown to contain at least two IAA oxidases about pI 5 and pI 10, mol. weight 30,000 and with a pH optimum 5.1–5.7. The enzymes require Mn2+, 2,4‐dichlorophenol and orthophosphate for the maximum activity. Attempts to separate IAA oxidase and peroxidase activities of the enzymes were unsuccessful.
The Effect of Cold Storage on Some Enzyme Activities in Tulip Bulbs
Authors: HAALAND ELLEN 
Published: April 2006

AbstractThe activities of α‐amylase, α‐glucan‐phosphorylase, and β‐fructofuranosidases were measured in an extract of soluble proteins of tulip bulbs of the cultivars “Apeldoorn” and “Paul Richter” stored for 2, 4, 6, 8, 10, and 12 weeks at 5°C. The enzyme activities increased during the first 4–6 weeks and then remained approximately constant during further storage at 5°C. 14C‐fructosyl‐sucrose oligosaccharides were identified after injection (into bulbs) of O14C‐U‐sucrose, thus showing fructosyl transferase activity.