bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Influence of Protochlorophyllide, Formed from Exogenous δ‐Aminolevulinic Acid, on Chlorophyll Synthesis in Leaves during Flash Illumination
Authors: Steer B. T. 
Published: April 2006

AbstractIn the presence of large accumulations of protochlorophyllide, derived from exogenous δ‐aminolevulinic acid, chlorophyll synthesis in excised leaves of two varieties of barley was less than in untreated leaves. In oat leaves the accumulated protochlorophyllide, from exogenous δ‐laminolevulinic acid, stimulated chlorophyll synthesis to above the control level. — These relationships could only be demonstrated when phtodestruction of pigments was minimised by the use of flash illumination (2 milliseconds every 3 minutes). — These was no evidence from in vivo absorption spectra that the pigments in the barley leaves were different to those in leaves studied by other workers. However, the presence of the accumulated protochlorophyllide appeared to prevent the shift of the chlorophyll absorption maximum from 673 nm to 677 nm. — Possible mechanisms of inhibition are discussed.
Changes in Uptake Capacities of Phosphorus and Calcium during Callus Induction in Rice
Authors: Nishi Toyoyuki 
Published: April 2006

AbstractChanges in the uptake capacities of phosphorus and calcium during callus induction in rice were examined as the first approach to the understanding for the possible mechanism of callus induction. A decrease in the capacity of phosphorus uptake and an increase in that of calcium was found during callus induction.
Eisen‐ und manganhaltige Verbindungen im Blutungssaft von Helianthus annuus
Authors: Höfner W. 
Published: April 2006

AbstractBleeding sap of sunflower seedlings (Helianthus annuus) which had been transferred to 59Fe‐ or 54Mn‐labelled nutrient solution 16 hours before decapitation, was fractionated by gelfiltration on Sephadex G‐15.In both the 59Fe‐ and the 54Mn‐labelled bleeding sap three fractions could be determined, containing the microelement together with amino acids and carbohydrates.According to the results of gelfiltration, the molecular weight of these compounds ranges below 1500.
Ultraviolet Inactivation and Photoreactivation in Synchronized Chlorella
Authors: Taube ÖRn 
Published: April 2006

AbstractSynchronous cultures of Chlorella pyrenoidosa have been used in studies of the action of UV‐irradiation during different stages in the life cycle on cell division capacity. These experiments show that there is a considerably higher sensitivity to UV‐irradiation during the first hours of the life cycle.The variations in photoreactivating capacity of UV‐damaged cells during a life cycle have been investigated. The results from these investigations show that the photoreactivating capacity varies and that it is higher in young daughter cells (autospores) and 12–15 hour cells. These variations can be due to variations in the activity of the photoreactivating enzyme during the life cycle.
Studies on Cytokinins in Watermelon Seeds
Authors: Prakash Ritu , Maheshwari S. C. 
Published: April 2006

AbstractExtracts of immature seeds of watermelon contain three cytokinins which are adsorbed on Dowex 50W ion exchange resin. The Rf of the fastest moving factor is similar to that of zeatin. The slowest moving factor is insoluble in n‐butanol and shows some resemblance to zeatin ribotide. The chromatographic properties of the second factor are, however, different from those of any of the known cytokinins and is believed to be new to literature.
Promotion of Growth and Flowering and Increase in Content of Endogenous Gibberellins in Gladiolus Plants Treated with the Growth Retardant CCC
Authors: Halevy A. H. , Shilo Ruth 
Published: April 2006

AbstractApplication of the growth retardant CCC to gladiolus plants resulted in stimulation of stem lenth, increased number of flowers per spike and a slight advancement of anthesis date. Leaves of treated plants were heavier than control and contained a higher amount of water and chlorophyll. The anthocyanin content in petals was also greatly increased. CCC had little or no effect on the content of the endogenous gibberellins in the acidic ethyl acetate fraction, but markedly increased the content of the native gibberellins in the aqueous fraction. The mode of action of CCC in plants is discussed on the basis of these results and a review of the literature.
Regulative Systems in the Developing Citrus Fruit I. The Hormonal Balance in Orange Fruit Tissues
Authors: Goren R. , Goldschmidt E. E. 
Published: April 2006

AbstractThe regulative systems of auxins, gibberellin‐like substances and their inhibitors in citrus fruit were studied. Masking caused by a high content of inhibitors was eliminated by using a refined method of solvent partition. Considerable amounts of auxins and gibberellin‐like substances were detected in all stages of fruit development. The auxin system of the citrus fruit is highly complex and consists of various elements which undergo dynamic changes throughout the growth period. The identity of the auxins was studied using IAA‐2‐14C, and 88% of the radioactivity specifically migrated into the etheric pH 6.0 fraction. Although the prominent zones of promotion do not coincide with IAA, it can be concluded that the auxin promoters are probably not the “citrus auxin”. Abscisic acid‐like inhibitors were found to accumulate in the external layers of the fruit, increasing in content as time advances.
Control of Rooting and the Pattern of Senescence in Detached White Mustard Cotyledons
Authors: Moore Keith , Lovell Peter 
Published: April 2006

AbstractSenescence of detached mustard cotyledons was greatest in full light or at low light intensity but was reduced at intermediate light intensities. The location of yellowing in the blade depended on the conditions in which it was maintained after excision. Cotyledons cultured at full light intensity in the absence of exogenous nutrients formed roots at the base and yellowed around the margins. Reduction in light intensity and increasing nutrient concentrations resulted in an increasing proportion of the cotyledons yellowing from the base upwards, and fewer developed roots. At low light intensity with high nutrient levels rooting was suppressed and basal senescence predominated.The location of yellowing in the cotyledon may be associated with mobilisation gradients induced by the differential effects of light and mineral nutrient level on root initiation and blade growth.
Diffusion and Quasi‐diffusion Resistances in Relation to the Carboxylation Kinetics of Maize Leaves
Authors: Gifford R. M. , Musgrave R. B. 
Published: April 2006

AbstractA “quasi‐diffusion resistance”, rq, is defined to accommodate the role which the thermochemical and photochemical phenomena of photosynthesis play in the control of CO2 fixation to the terminology and approach of the diffusion resistance analogue for the CO2 exchange of leaves. The relationship of rq to Rabinowitch's classical rectangular hyperbolic model of photosynthesis rate as a function of CO2 concen‐tration at the carboxylating surface is discussed. Examination of Kmapp for phos‐phopyruvate carboxylase (the predominant carboxylase in maize) suggests, as a reasonable hypothesis for light‐saturated maize leaves, that rq may be essentially independent of ambient CO2‐concentration up to at least 300 μ1/l. A corollary of the hypothesis is that an increase of diffusion resistance, rather than of rq, may account for the observed curvature of the response curves of light‐saturated maize leaf photosynthesis to ambient CO2‐concentration. An experiment carried out on fieldgrown maize plants, using a well controlled leaf chamber as a nitrous oxide diffusion porometer, gave evidence which strongly supported the hypothesis.
Cytokinin Production by Rhizobium japonicum
Authors: Phillips Donald A. , Torrey John G. 
Published: April 2006

AbstractPossible hormonal interactions between soybean roots and the Rhizobium initiating nodule proliferation in this genus were studied. A cytokinin has been isolated by column and paper chromatography from an effective strain of Rhizobium japonicum grown in pure culture. The substance promotes cell proliferation in a cytokinin‐requiring soybean callus tissue. The bacteria are capable of conditioning a cylokinin‐free soybean culture medium so that it is able to support the cytokinin‐requiring tissue. It is concluded that the substance is a product of the bacteria rather than an artifact of purification. This unidentified cytokinin or a substance moving to a similar Rf value on the paper chromalogram produces polyploid divisions when tested on cultured pea root segments. Some of the division figures exhibit the diploclirornosomes typical of the root nodule primordium in pea.
Seasonal Variations in GA3 Effects on Flowering of Impatiens balsamina, a Qualitative Short Day Plant
Authors: Nanda K. K. , Tory K. L. , Sawhney S. 
Published: April 2006

AbstractThe effectiveness of GA3 in inducing floral‐bud initiation in Impatiens balsamina under non‐inductive photopcriods varies considerably at different parts of the year and appears to be determined by the prevailing temperature conditions. The period of floral‐bud initiation is shortest in October and February and increases both with decreasing temperatures in November and with increasing temperatures in August and September. Floral buds do not initiate in March and April, during which time the temperature increases considerably subsequent to the start of experiment.
Distribution and Isoenzymes of Aspartate Aminotrans‐f erase in Cotyledons of Germinating Pumpkins
Authors: Splittstoesser Walter E. , Stewart Sheryl A. 
Published: April 2006

AbstractDuring germination a steady decline in the reserve protein occurred in dark grown pumpkin cotyledons. By 9 days, 80% of this nitrogen reserve was hydrolyzed but only 50 % was removed from the cotyledons. The remaining nitrogen (30 %) was incorporated into water soluble protein which reached a maximum 9 days after germination. The increase in water soluble protein in pumpkin cotyledons parallel the increase in soluble and particulate aspartate aminotransferase (E.C.2.6.1.1.), suggesting that this enzyme is involved in nitrogen metabolism during germination. Little enzyme activity was found in pumpkin tissues other than the cotyledons.Four anodally moving isoenzymes were found in the soluble aspartate aminotrans‐ferase fraction and 3 anodally moving isoenzymes were found in the particulate fraction. The slowest moving isoenzymes disappeared first during germination.
Influence of 2‐Chloroethylphosphonic Acid on Anthocyanin Formation, Size, and Yield in Vaccinium macrocarpon cv. Early Black
Authors: Devlin Robert M. , Demoranville I. E. 
Published: April 2006

AbstractThe influence of 2‐chloroethylphosphonic acid (CEPA) on yield, size and pigmentation of cranberries (Vaccinium macrocarpon cv. Early Black) was investigated. Applications of CEPA at 100, 500, and 1000 mg/1 to cranberry vines before bloom and during peak bloom have an adverse effect on yield and size. CEPA applied at these times has litlle influence on color. Applications of CEPA two weeks before harvest significantly accelerates pigment development, peak effect being observed when the vines are treated with 500 mg/1. Size and yield are not noticeably influenced at this time. The possible use of CEPA in the commercial production of cranberries to stimulate color development is considered.
Effect of α‐Naphthalene‐ and α‐Naphthoxyacetic Acid on the Activity of Certain Enzymes of Atropa belladonna cv. lutea Cells in Suspension Culture
Authors: SIMOLA LIISA KAARINA , SOPANEN TUOMAS 
Published: April 2006

AbstractThe growth of Atropa belladonna cv. lutea Döll cells and the activities of several enzymes were studied as a function of time in suspension cultures without added auxin, with α‐naphthaleneacedc acid (NAA) and with α‐naphthoxyacetic acid (NOA). The growth curves were rather similar and therefore easy to compare. The enzyme activities (per mg dry weight of culture) were distinctly higher in cultures grown with NAA than in the other two treatments, in which root formation was common. In some cases the enzyme activities were lower in cultures with NOA than in the control series but usually the curves were quite parallel. Promotion of enzyme activities by NAA (aldolase, aminopeptidase, gluta‐mate: oxaloacetate transaminase) was clearest in the beginning of the phase of rapid cell division (6‐day‐old culture). These three enzymes reach their maxima at this stage of growth in the other series as well. Ribonuclease activity increased in the stationary phase cells (13 and 19 days) with NAA but with the other treatments the level of this activity was relatively stable. Peroxidase and phosphatase did not show any characteristic maxima, glutamate: pyruvate transaminase activity was low and no amylase activity could be demonstrated. The results indicate that synthetic plant growth substances can regulate the physiological state of a tissue by causing alterations in enzyme activities, but their action is clearly specific.
Seasonal Variations in the Occurrence of Indole‐3‐Acetic‐Acid in Buds of Pinus silvestris
Authors: ALDEN TORSTEN 
Published: April 2006

AbstractStudies with a fluorescence spectrophotometer and gas chromatography confirm earlier results that IAA occurs in buds and sprouting shoots of Scots pine. IAA could be found during the whole vegetation period but not during winter dormancy. The largest amount was obtained during shoot growth in spring and early summer. During the most intensive elongation phase, a gradient could be found in the concentration of auxin with the highest amount in the basal part and a decreasing concentration upwards in the shoot.
Extracellular Lytic Enzymes of Myxococcus virescens
Authors: HASKA GUNO 
Published: April 2006

AbstractThe aim of the investigation was to obtain large amounts of the bacteriolytic enzymes of Myxococcus virescens and to separate these enzymes from the non‐bactcriolytic protemases produced by this organism.The bacteria were grown in Casitone broth. When the bacteriolytic activity had reached its maximal value, the cells were removed from the culture medium by centrifugation. Polyethylene glycol 4000 (20 g/1) and potassium phosphate (about 210 g/1) were added to the cell‐free solution. The additions resulted in the formation of two liquid phases. The bottom layer was removed, and polyethylene glycol was added to it at a final concentration of 10 g/1. Again two liquid phases formed. The two top phases thus obtained were pooled and 1.6 volumes of cold acetone were added to the mixture. The precipitate formed was dissolved in water and desalted on a Sephadex G‐25 column. The desalted protein solution was applied to a carboxymethyl‐cellulose column equilibrated with 0.025 M sodium phosphate buffer of pH 6.0. Most of the proteins and the proteinases but none of the bacteriolytic enzymes passed the column unadsorbed. The column was washed with 0.05 M glycine‐NaOH buffer of pH 8.8, whereupon the adsorbed bacteriolytic enzymes together with small amounts of proteinases and other proteins were eluted with 0.2 M ammonium carbonate.The material not adsorbed on the CM‐cellulose column contained 22 % of the proteolytic activity of the initial cell‐free solution and had a 26‐fold higher specific activity. The enzyme solution eluted with carbonate contained 24 and 0.3 %, respectively, of the initial bacteriolytic and proteolytic activities. The specific activity of the bacteriolytic enzyme system was about 5000‐fold higher than that of the original solution.
Subcellular Organization of Developing Embryos of Bidens cernua
Authors: SIMOLA LIISA KAARINA 
Published: April 2006

AbstractAnatomical and submicroscopical changes in the cotyledons and radicles of Bidens cernua L. have been studied at five developmental stages. In the subcellular structure, these two plant organs are relatively similar but each developmental stage is characterized by a distinct fine structure. Protein bodies, which occupy the bulk of the cell in dormant embryos, develop as filling products of vacuoles. Ribosomes are seen abundantly at this stage, both in the nucleus and the plasma strands. Small vesicles which are the initials of globoids can be detected in the vacuoles even of rather young cells. They later associate at the periphery of protein masses secreted in the vacuoles. Many light globoids are seen in the protein bodies of mature cells. Some amyloplasts are present in the early developmental stages but not in the dormant cells. The endoplasmic reticulum becomes filled with osmiophilic storage fat, and later many spherosomes are seen between the protein bodies. Some osmiophilic material is also found in the intercellular spaces.
Growth Regulators in Populus tremula
Authors: ELIASSON LENNART 
Published: April 2006

AbstractThe seasonal variation in capacity to form suckers and in auxin level in bark and wood was determined in root segments of aspen (Populus tremula L.). Auxin occurred in the roots from May to October but not in November. The highest auxin level was found during the period of shoot growth. During this period the capacity of root segments to form suckers was low. Auxin level decreased in isolated root segments during the first 24 hours after excision and was low during the period of sucker induction. The relation of endogenous auxin level to control of sucker formation is discussed. The experiments do not exclude the possibility that the auxin effect is mediated through inhibitors.
Regulation of Growth and Invertase Activity by Kinetin and Gibberellic Acid in Developing Avena Internodes
Authors: JONES R. A. , KAUFMAN P. B. 
Published: April 2006

AbstractEvidence presented here indicates that there is a complex interaction between kinetin, gibberellin, and sucrose in the regulation of turnover of invertase in vivo. The synthesis of invertase is maintained in the presence of GA3 and sucrose over relatively long periods of time. Kinetin, on the other hand, inhibits the full development of invertase activity seen in the sucrose and gibberellin control treatments. Moreover, the peak in invertase activity occurs earlier with kinetin treatment. During invertase turnover, once the peak is reached, kinetin enhances the rate of decay of enzyme activity relative to synthesis. The regulatory significance of invertase in intercalary growth and possible modes of kinetin action in this process are discussed.
Boundary Layer Effects in Ion Absorption by Roots and Storage Organs of Plants
Authors: POLLE E. O. , JENNY HANS 
Published: April 2006

AbstractIn plant nutrition studies with culture solutions it is tacitly assumed that replenishment of ions at the root surface is guaranteed by the turbulence of the stirred solution. That this belief may be erroneous is demonstrated in this study with barley roots and discs of beet roots and potato tubers. At very low concentrations of RbCl (in presence of CaCl2) the uptake of Rb by roots is strongly controlled by the rate of stirring. The results are interpreted in the light of the Nernst hydrodynamic boundary film which surrounds solids and through which ions must diffuse to reach the root surface. “Film‐controlled” and “root‐controlled” ion uptake is visualized.
The Change in Arginine Levels and the Metabolism of Urea and Ornithine in Cucurbita moschata Seedlings
Authors: LIGNOWSKI EDWARD M. , SPLITTSTOESSER WALTER E. 
Published: April 2006

AbstractDuring germination a decrease in both soluble and protein argmine occurs in pumpkin cotyledons (Cucurbita moschata Poir.) and this decrease parallels the decrease in total nitrogen. Arginine is readily metabolized to urea and ornithine and the metabolism of the latter compounds were studied by allowing cotyledons of intact plants to absorb urea−14C and by incubating cotyledon discs with ornithine‐2−14C. Of the urea absorbed, 90 % of the label was metabolized to 14CO2 with little free urea remaining in the plant. Urease activity in the cotyledons reached a maximum at 4 to 6 days of germination. Ornithine was extensively metabolized with 37 % of the label being incorporated into protein by 3 h. Soluble and protein arginine accounted for 23 % of the label suggesting that Krebs‐Henseliet cycle enzymes were present.
Inhibition de ľAccumulation des Chlorophylles dans les Feuilles Primordiales de Phaseolus vulgaris après Irradiation Neutronique
Authors: KIRCHMANN R. 
Published: April 2006

AbstractEtiolated bean leaves have been irradiated in an experimental cavity of a nuclear reactor. The greening is allowed either under continuous light or under intermittent light. A relationship between the decrease of the chlorophyll accumulation and the exposure dose is observed; moreover, the accumulation of chlorophyll b is more strongly decreased than the accumulation of chlorophyll a, by irradiation. A recovery phenomenon of the chlorophyll accumulation has been observed.Ľauteur remercie le Personnel du Service Exploitation du BR1 et du Département de la Physique des Réacteurs pour le concours précieux apporté, ainsi que Messieurs E. Fagniart, Y. Hauglustaine et Madame El. Bonnijns‐Van Gelder pour leur collaboration technique.
Orientation and Geotropic Reaction of Seminal Roots of Wheat
Authors: BURSTRÖM H. G. 
Published: April 2006

AbstractThe geotropic orientation of seminal roots of wheat has been studied on seedlings grown in five different positions, stationary and on clinostats. The roots perceive a geoinduc‐tion before they have emerged from the grain and perform curvatures inside the grain. These are very sharp and transient, the following root growth is straight in any direction unless the positions are shifted. The roots are insensitive to a static gravi‐induction but react to a change in gravitation with a geotropic curvature in positive direction. The roots may not reach or reach, or even pass the plumb‐line. The orientation of a root depends upon the direction of its initiation and the geotropic curvature attained before the reaction has ceased. There is no nastic component in the reactions. The ‘plagiotropic’ orientation is explained by the limited positive reaction followed by an ageotropic state. Main root and adventitious roots react in the same way. Reactions to later stimuli give likewise limited curvatures which are weaker but of longer duration. — The effect of temperatures from 10°C to 25°C has been studied and compared to the temperature effect on cell elongation. It is concluded that the whole reaction may be explained by the regular auxin effects on cell elongation. No other hormone should be required and no plagiotropic mechanism is necessary.
Effect of Ammonia and Nitrate on Growth, Photosynthesis, and Ribulosediphosphate Carboxylase Content of Dunaliella tertiolecta
Authors: PAASCHE E. 
Published: April 2006

AbstractWhen the marine Chlorophycean flagellate Dunaliella tertiolecta Butcher was grown with short photoperiods of bright light, the use of ammonia rather than nitrate as a nitrogen source led to a 30 % reduction of the doubling time of cell matter. The cell cycle (onset of light to completion of cell division) was shortened by about 10% only. Ammonia‐grown cells possessed a greater capacity for photosynthetic oxygen evolution at light saturation than did nitrate‐grown cells; their content of ribulosediphosphate carboxylase was likewise greater. The faster growth of Dunaliella tertiolecta with ammonia may be partly a consequence of a general increase in net protein synthesis resulting in a greater content of photosynthetic enzymes.
Simple Methods for the Calibration of Light Measuring Equipment
Authors: BJöRN L. O. 
Published: April 2006

AbstractSimple methods are described for

absolute calibration of thermal radiation detectors (thermopiles, bolometers);
absolute calibration at various wavelengths of photoelectric devices;
obtaining the relative spectral sensitivity of the detector systems of spectrofluorimeters.

The procedures require no special standard lamp or other exotic equipment. The methods depend on the computation of the radiation characteristics of an ordinary tungsten lamp at various measured voltages and currents.