bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cytokinin Activity in Begonia and Bryophyllum
Authors: Heide Ola M. , Skoog Folke 
Published: April 2006

AbstractCytokinin activity has been obtained in ethanol extracts of Begonia and Bryophyllum plants. Begonia x cheimantha Everett yielded 30 to 300 μg kinetin equivalents per kg of fresh leaves in the tobacco callus bioassay. Short day conditions appeared to increase the extractable cytokinin content in the tissue.Purification by fractionation on Dowex 50 H+ columns followed by organic solvent extraction, silver precipitation, and repeated paper chromatography yielded an apparently homogeneous product which accounted for most of the activity in the Begonia extracts. It was indistinguishable from zeatin in chromatograms developed with six solvent systems.Other cytokinin active fractions were also obtained from both Begonia and Bryophyllum. Crystalline picrate preparations of active products were insufficient for identification by mass spectrometry.
Croissance et synthese des proteines de suspensions cellulaires de Tabac sensibles à la kinétine
Authors: Jouanneau Jean‐Pierre , Péaud‐Lenoël Claude 
Published: April 2006

AbstractCulture conditions, allowing the unlimited growth and maintenance in shaken suspensions of a kinetin dependent strain of tobacco pith cells, were determined.Cell clusters from 1 to 25 cells were selected from the cultures to study the cell multiplication after addition of specific growth factors to the basal medium. Cell division was found to be strictly dependent upon the presence in the medium of both kinetin and auxin. In complete medium the generation period was 45 to 49 hours.Kinetics of the total protein synthesis in the cell suspensions have been measured either by estimation of protein nitrogen or by 35S incorporation into the proteins. After 3 days of culture, growth was exponential, as expressed by cell number or protein synthesis, which varied proportionally. Evidence was also found that the initial incorporation rate of radioactivity into the proteins was more rapid than expected from the increment of the protein net weight. It seems therefore reasonable to assume that a significant amount of protein turn over does exist during the initial period of growth. This phenomenon was observed even when no cell division occurred.Kinetin significantly activated protein synthesis, whether or not auxin was present in the medium.
The Interrelation of RNA, Auxin and Auxin‐oxidases in Lentil Roots
Authors: Pilet P. E. , Braun R. 
Published: April 2006

AbstractThe correlation between auxin and RNA metabolism was investigated in lentil roots. IAA and NAA both cause a considerable rise in the RNA level of germinating lentil roots, though no effect of IAA was found on the DNA level. In untreated germinating roots various sections were isolated and a direct relation found between RNA and auxin content, and an indirect relation between RNA content and auxin oxidase activity.In excised roots, incubated for 24 hours, the loss of RNA is paralleled by a loss of endogenous auxin. Excised roots treated with 10−4M IAA or M 10−4 NAA loose little RNA.The findings suggest that in lentil roots the RNA levels may be controlled by auxin levels, which in turn may be controlled by the levels of auxin oxidase.
Effect of Different Gibberellins on the Growth of the Hypocotyl
Authors: Rai Vinay K. , Laloraya Manmohan M. 
Published: April 2006

AbstractIt has been stated earlier that hypocotyls of different plants show different growth response to added GA3. It was suggested that this difference may be due to the requirement of some specific gibberellin. Hence hypocotyl growth response of three groups of plants has been studied with different gibberellins: group one showing no or insignificant growth response, group two showing 150–200 per cent growth response and group three showing 300–500 per cent growth response to added GA3. Eight gibberellins were used, viz., GA1, GA2, GA3, GA4, GA5, GA7, GA8 and GA9, to test if this varying response is connected with the requirement of some specific gibberellin. In general, the results obtained do not favour this view. Iberis amara, a plant showing no response to added GA3, Dianthus sp., a plant showing 150 to 200 per cent response and Lactuca satwa, Antirrhinum majus and Nicotiana tabacum, plants showing 300 to 500 per cent response, were promoted by all the gibberellins tested to a similar extent as by GA3, with the exception of GA8 which was inactive in most of the cases.
Effects of Exudation on Ion Relationships of Excised Roots
Authors: Greeenway H. 
Published: April 2006

AbstractIn excised tomato roots submerged in solution, mannitol at –2.8 atm increased the phosphorus uptake and decreased the loss of previously absorbed phosphorus.Separate collection of the xylem exudate demonstrated that these mannitol effects were due entirely to a reduced phosphorus flow via exudation. For example, in the case of previously absorbed phosphorus, the high loss of phosphorus at –0.3 atm could be contributed to phosphorus transport via the exudation stream, which was higher at –0.3 than at –2.8 atm. In contrast, loss from the root surface to the external medium was identical for the two different water potentials.The neglect in measuring ion flow in the exudate might have confounded ion transport studies by other workers. Some particular cases were re‐examined, such as chloride uptake at high external concentrations and ion toss from different cell compartments.
Copper Oxidases in Thalli of the Liverwort Marchantia polymorpha
Authors: Poucke M. Van 
Published: April 2006

AbstractA study is presented on the properties of copper oxidases in thalli of the liverwort Marchantia polymorpha L. Catecholase and ascorbic acid oxidase are compared in their specific activity, reaction kinetics, inhibitor sensitivity and intracellular localization. It is shown that catecholase is predominantly bound to particulate cell fractions and is normally inhibited by the usual inactivators of copper enzymes. Ascorbic acid oxidase activity, on the other hand, is strongest in the soluble protein fraction and is quite resistant toward the same inhibitors at the pH‐optimum of the enzyme. Both enzymes, when assayed with small tissue fragments, can be inhibited as expected.
A Theory for Circumnutations in Helianthus annuus
Authors: Israelsson D. , Johnsson A. 
Published: April 2006

AbstractA theory is given for circumnutations in plants, especially hypocotyls of Helianthus annuus, which were used as experimental materialThe theory is based on the lateral auxin transport, which arises when a gravitational force component acts on the plant. With a suitable time delay between stimulus and response, oscillations or circumnutations should arise. It is possible to describe these oscillation phenomena by the solutions of a differential equation, derived in this paper. The time delay has a central role in this equation.The time delay is assumed to be identical with the geotropic reaction time for the hypocotyls. The ratio between the periodic time for the circumnutations and the reaction time for geotropic curvatures was found to be approximately constant in the temperature region investigated (namely 15–40°C), which supports the theory. Different methods of recording the circumnutations were used, 8 mm film camera technique being the most frequently employed.The introduction of a weighting function for describing the plants “memory” of the stimulation makes it possible to relate the periodic time of the circumnutations to the reaction time for geotropic curvatures. The necessity of this weighting function as well as of the time delay in the equations is emphasized. An explanation of the “Fünfphasen‐bewegungen”, reported in the literature, is presented.
Photometrically Assayable Phytochrome in vivo in Callus Tissue Cultured from Nicotiana tabacum
Authors: Kasperbauer M. J. , Reinert R. A. 
Published: April 2006

AbstractPhytochrome was photometrically detected in callus tissue cultured from tobacco stem pith. Our previous work with such tissues showed a growth response to red light, and a nullification of the effect of red by far‐red light. Tissues that were subcultured for 4 or 20 months were assayed. Tissues of the younger clone had the most detectable phytochrome. Also, tissues cultured in darkness and those exposed to 5 minutes of red light each day bad more detectable phytochrome than tissues grown under 16‐hour photoperiods of low intensity white light. We gratefully acknowledge Drs. H. A. Borthwick and J. E. Scheibe for use of facilities and assistance in operating the dual‐wavelength photometer at the U.S.Department of Agriculture Pioneering Research Laboratory for Plant Physiology at Beltsville, Maryland.
Indoleacetic Acid and Molecular Differentiation Evidence for Interaction
Authors: Sarkissian Igor V. , Spelsberg Thomas C. 
Published: April 2006

AbstractProteins of hypocotyls of bean were studied by electrophoresis. Proteins were extracted from hypocotyl segments of various stages of development starting with the relatively undifferentiated hook regions and proceeding by 2 cm segments down the hypocotyl. The proteins were the soluble (pH 7.4), the basic nuclear (histones), acidic ribonuclear and acidic chromosomal.Soluble proteins reflected differentiation of the hypocotyl in that lower hypocotyl segments had more different protein types than did the hook region. Indoleacetic acid (IAA) at 10−6M when applied to the lower hypocotyl appeared to induce still more different proteins. However, at 10−3M, IAA appeared to induce molecular dedifferentiation in that hypocotyl protein patterns began to resemble those of the hook.Histones also reflected differentiation, the hook having more histone types than the lower hypocotyl. IAA had no effect on histones.The hook region had two types of acidic chromosomal proteins, the lower hypocotyl one. When lower hypocotyl segments were incubated in 10−3M IAA, the protein pattern resembled that of the hook in that the second protein normally present in the hook and not in the hypocotyl was in fact induced in the hypocotyl.The hook had two acidic ribonuclear proteins, the lower hypocotyl one. IAA did not affect this protein.These experiments suggest that IAA in some manner regulates molecular (protein) differentiation. It is further suggested that IAA accomplishes this control through the acidic nuclear proteins which are closely associated with genetic material and which reflect differentiation and are also affected by IAA.
Dependence of Lettuce Seed Germination on Actinomycin D‐resistant RNA Synthesis
Authors: Khan Anwar A. 
Published: April 2006

AbstractThe response of Grand Rapids lettuce half seed and intact seed to different nucleic acid and protein synthesis inhibitors was studied. 6‐azauracil, 2‐thiouracil and cycloheximide were strong inhibitors of germination of intact seed as well as of radicle elongation of half seed. Inhibition by 6‐azauracil and 2‐thiouracil was reversed by uracil but not by orotic acid, thymine or deoxycytidine. Actinomycin D and puromycin were ineffective suggesting that actinomycin D‐resistant RNA synthesis possibly controls both germination of intact seed and radicle elongation of half seed.The requirements of RNA synthesis for the elongation of radicle in half seed in light and in the presence of gibberellic acid was the same. Such was not the case in the germination of intact seed which had different requirements of RNA synthesis in light and in presence of gibberellic acid. It is concluded that the mechanism of gibberellic acid and light in the intact seed germination, in so far as it involves the regulation of RNA synthesis, depends on the integrity of the seed coats.
Modification of Sex Expression in Muskmelon by Treatment with the Growth Retardant B‐995
Authors: Halevy A. H. , Rudich Y. 
Published: April 2006

AbstractTreatment of an andromonoecious cultivar of muskmelon with N, N‐dimethylaminosuccinamic acid (B‐995) induced a shift towards femaleness. This tendency was expressed by a reduction in the number of staminate (male) flowers, an increase in the number of hermaphrodite flowers and a shift in flowering pattern resulting in the formation of hemaphrodite flowers at lower nodes.The treatment also caused a change in the habitus of the plants from the regular pole type to a dwarf type, which was manifested by a marked reduction in node length and the suppression of tendril formation.The mode of action of B‐995 on sex expression is discussed.
On the Mode of Action of Carbamate Herbicides
Authors: Keitt George W. 
Published: April 2006

AbstractThe hypothesis of Mann et al. that carbamate herbicides act as anti‐derepressor substances was tested in two systems: cell enlargement and proliferation in cultured tobacco pith, and auxin‐induced Avena first internode extension. Isopropyl‐N‐phenylcarbamate (IPC) and isopropyl‐N‐(3‐chIorophenyl carbamate (CIPC) both severely inhibited kinetin‐induced cell proliferation in tobacco pith at 10−6M. Auxin‐induced tobacco cell enlargement was inhibited to the same degree only at 10−3M. Avena internode extension was insensitive to these compounds in the range 10−3 to 10−7M of IPC and 10−4 to 10−8M CIPC. The results support but do not prove Mann's hypothesis. Results of various studies with carbamates are interpreted in terms of this mechanism.
Effect of Photoperiod, Auxins and Gibberellic Acid on Rooting of Stem Cuttings of Bryophyllum tubiflorum
Authors: Nanda K. K. , Purohit A. N. , Bala Adarsh 
Published: April 2006

AbstractPhotoperiod controls the initiation and development of roots on cuttings of Bryophyllum tubiflorum. Root initiation occurred when either the mother plant or the cuttings were exposed subsequently to SD conditions. Cuttings from LD plants exposed to LD did not root at all even after 4 weeks showing that short days are necessary for rooting of cuttings of this plant. The short day requirement can be substituted by IAA or IBA as roots were initiated in cuttings from LD plants when treated with the auxins under LD conditions. GA stimulates rooting of cuttings under SD conditions but does not replace the SD requirement. It failed to induce rooting under LD conditions.
Indoleacetic Acid‐Induced Decrease of the Ribomiclease Activity in vivo
Authors: Truelsen T. A. 
Published: April 2006

AbstractA study has been made on the influence of indole‐3‐acetic acid (IAA) on the ribonuclease (RNase) activity in wheat coleoptile sections and green pea stem sections. The hormonal effects on the enzyme activity, ribonncleic acid (RNA) metabolism and growth have been compared.Addition of 10−5M IAA to the plant sections causes their RNase activity to decrease and their elongation to increase. Removal of the added IAA results in increasing enzyme activity and decreasing growth. The altered enzyme activities are paralleled by opposite changes in the RNA net synthesis. Administration of crystalline RNase to the plant tissue depresses growth. There is thus evidence that the in vivo effect of IAA on the RNase activity is of importance for the hormonal regulation of RNA metabolism and growth.The IAA‐induced reduction in the enzyme activity involves cellular metabolism. The effect can be suspended by means of p‐chloromercuribenzoate. A possible mechanism for the reduction is discussed.
Carboxydismutase Activity in Shade‐adapted and Sun‐adapted Species of Higher Plants
Authors: Björkman Olle 
Published: April 2006

AbstractThe activity of the photosynthetic enzyme carboxydismutase (ribulose‐l,5‐diphosphate carboxylase) was measured in leaf extracts of a number of higher plant species from habitats with greatly contrasting light intensities. Plants occupying sunny habitats and capable of light saturated rates of photosynthesis several times higher than those growing in the deep shade of redwood forests also have a considerably higher carboxydismutase activity. Thus, when expressed on the basis of total chlorophyll or even fresh weight, the enzyme activity is several times greater among the sun than among the shade species.The comparatively low content of soluble protein in the shade plants indicates that their content of enzymes other than carboxydismutase also is low. Nevertheless, the activity of carboxydismutase even on the basis of soluble protein appears to be significantly higher in the sun than in the shade species.It is concluded that low carboxydismutase activity probably is one of the factors that limit the capacity for light saturated photosynthesis in the shade plants.
Oxidative Enzymes and Pathways of Hexose and Triose Metabolism in Chlorella
Authors: Devlin Robert M. , Galloway Raymond A. 
Published: April 2006

AbstractCell‐free preparations of Chlorella pyrenoidosa Chick, van Niel's strain, were assayed for oxidative enzymes, utilizing isotopic and spectrophotometric techniques. The enzyme activity of heterotrophic and autotrophic cells was compared.The study was divided into categories, one concerned with the spectrophotometric detection of enzymes involved in the initial reactions of glycolysis and the hexose monophosphate shunt, and the other with the direct oxidation of glucose as compared with that oxidized via glycolysis. The reduction of pyridine nucleotides in crude extracts was studied with glucose, glucose‐6‐phosphate, 6‐phosphogluconate, and fructose‐1‐6‐diphosphate as substrates. Enzymes detected in both heterotrophic and autotrophic cells were hexokinase, fructose‐diphosphate‐aldolase, NAD‐linked 3‐phosphoglyceraldchyde dehydrogenase, glucose‐6‐phosphate dehydrogenase, 6‐phosphogluconate dehydrogenase, and a NADP‐linked 3‐phosphoglyceraldchyde dehydrogenase.In addition to isotopic studies designed to make an appraisal of the hexose monophosphate shunt, a comparison of the rate of reduction of NADP by glucose‐6‐phosphate and 6‐phosphogluconate in relation to the reduction of NAD by 3‐phosphoglyceraldehyde was made in light‐ and dark‐grown cells. The rate of reduction of NADP appeared to be lowered in the light‐grown cells, suggesting, as did also the isotopic studies, that the hexose monophosphate shunt is less active in autotrophic metabolism than in heterotrophic metabolism.
Pathways of Carbohydrate Catabolism in Senescent and Non‐senescent Tobacco Leaves
Authors: Baur J. R. , Halliwell R. S. , Langston Ruble 
Published: April 2006

AbstractThe pathway (s) of glucose degradation in detached senescent and non‐senescent tobacco leaves from plants approximately 100 days old were studied utilizing‘Relabeled carbohydrates. Comparable samples of each tissue were allowed to metabolize glucose‐1‐ and glucose‐6‐14C and C6/C1 ratios were computed from the radioactivity of 14CO2 collected. Two methods of calculation were compared.Hexose monophosphate pathway activity was also compared in both ages of tissue by measuring 14CO2 respired from substrate ribose‐1‐, xylose‐1‐ and gluconic acid‐6‐14C.The results indicate that the hexose monophosphate pathway accounts for approximately 25 percent of the respired CO2 in both senescent and non‐senescent tissues. Both types of tissue were equally efficient in degrading HMP shunt intermediates to CO2.
The Influence of Medium Composition and Additions of Animal Origin on the Formation of Capture Organs in Arthrobotrys oligospora
Authors: Nordbring‐Hertz Birgit 
Published: April 2006

AbstractThe formation of capture organs for nematodes in A. oligospora. and its dependence on substrate composition and additions of animal origin was studied in laboratory experiments. Variations in only the substrate composition did not give rise to capture organ formation. If nematodes were present, however, the medium composition was of great importance for the number of traps formed. Capture organs were not only formed in the presence of nematodes but also by addition of other taxonomically diverse animals such as earthworms, fly‐larvae and spring‐tails. The initialing factor is, for full effect, bound to the living state and not confined to nematodes. For biological control of nematodes with the aid of nematode‐trapping fungi, therefore, the effect of the other microfauna of the soil should also be taken into consideration.
Marine Plankton Algae Grown with Light‐Dark Cycles.
Authors: Paasche E. 
Published: April 2006

AbstractThe diatoms Ditylum brightwellii and Nitzschia turgidula were grown in semi‐continuous culture under various combinations of light intensity, temperature and daylength (photoperiod). Growth was strongly limited by light intensities below 0.03 cal/em2. min in both species. Above this intensity, light saturation of growth was rapidly approached in Nitzschia but only gradually so in Ditylum. The growth rate in continuous light was never significantly higher than with 16 hours of light plus 8 hours of dark. In Ditylum, continuous light above 0.03 cal/cm2. min caused a strong inhibition of growth at all temperatures. The chlorophyll concentration in the cells was greater the shorter the photopceriod. In cultures synchronised by different combinations of light intensity and photoperiod, cell division generally took place in the light. Synchrony was best under short photoperiods of bright light. Time courses are shown for chlorophyll synthesis and photosynthesis in synchronised cultures.
The Effect of Kinetin on Protein Level of Brassica Leaf Disks
Authors: Kuraishi Susumu 
Published: April 2006

AbstractThe senescent leaf disks from Brassica rapa L. were floated on a medium containing 14C‐L.‐leucine in the presence or absence of kinetin. The increase in radioactivity in protein fraction of kinetin‐treated disks was almost linear with time, while the increase in untreated disks incubated for 3 days started to slow down. The leaf disks were first incubated on the solution of 14C‐L‐leucine and then transferred to either kinetin solution or water in order to study whether the slower incorporation is due to the decreased rate of protein synthesis or that of protein retention. The decrease in radioactivity of disks floated on kinetin was slower than that of disks floated on water. The slower decrease in radioactivity caused by kinetin was not due to an increased turnover rate, since the same phenomena were observed in the presence of cold leucine or casein hydrolysate solution. These results suggest that kinetin retards the decomposition of protein in leaf disks and does not stimulate the synthesis of the bulk of protein.