bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Diurnally Fluctuating vs. Constant Temperatures on Flower Induction and Sex Expression in the Olive (Olea europaea)
Authors: BADR SAYED A. , HARTMANN HUDSON T. 
Published: April 2006

AbstractOlive trees must be exposed to a period of winter chilling temperatures in order to form inflorescences the following spring. The effects of diurnally fluctuating and constant temperatures on flower induction and sex expression in the olive were compared under controlled environment conditions. The effect on flowering of diurnally fluctuating temperatures depends upon the length of time at the higher temperatures. While daily exposure to the high temperatures (21° to 26°C) for a short period (four hours) intensified the effectiveness of the low temperatures (7° to 12.5°C), when the high temperature duration was 12 hours it counteracted the low temperature action. Possibly, daily low temperatures act to stimulate reactions leading to floral hormone synthesis, while daily short exposures to high temperatures act to maintain metabolic activity, promote energy‐yielding reactions, and possibly stimulate cell‐division activity. In the olive, an intermediate constant temperature (12.5°C) favors both types of reactions and induces flowering; however, in this case, the pistils fail to develop. The olive has very specific temperature requirements for flowering and neither the mean temperature nor the accumulated number of hours below a given value, e.g. 7°C, adequately characterizes these requirements.
Photosynthesis in Sugarcane Varieties Infected with Strains of Sugarcane Mosaic Virus
Authors: IRVINE JAMES E. 
Published: April 2006

AbstractSymptoms of sugarcane mosaic virus disease caused by strains B and D were accompanied by a reduction in the rate of photosynthesis per unit area; the severe symptoms of strain A and the mild symptoms of strain I produced rates no different from those of healthy plants of variety C.P. 31‐588. All four strains decreased chlorophyll content and increased the amount of light transmitted by the leaf. Photosynthetic rates were reduced less than the reduction of chlorophyll would indicate. Symptoms moderated on older leaves, but rates of photosynthesis per dm2 were less in older leaves of both healthy and diseased plants. Sugarcane varieties differed in their rates of photosynthesis in both healthy and in virus‐infected plants; a significant reduction in photosynthetic rate by sugarcane mosaic occurred in three of the four varieties.
Polyglucan Branching Isoenzymes of Algae
Authors: FREDRICK JEROME F. 
Published: April 2006

AbstractThe cyanophyte, Oscillatoria princeps, and the enigmatic hot‐spring alga, Cyanidium caldarium, contain two branching isoenzymes which can act on amylose and amylopectin, converting these polyglucans into highly branched phytoglycogens. The red alga, Rhodymenia pertusa contains three branching isoenzymes, only one of which is capable of the dual activity of the other algal branching isoenzymes. The other two red algal branching isoenzymes are Q enzymes and can only act on amylose, forming moderately branched amylopectìns. However, when the isoenzymes of all three algae are separated on different concentrations of polyacrylamide gel via electrophoresis, the mobilities of the isoenzymes show that the Q enzymes and the branching enzymes are related and true isoenzymic molecules. They differ only in electrical charges, probably caused by the substitution of amino acid residues in their active peptides. It is possible that if these charge isomers are due merely to amino acid substitutions, the enzymes may have been originally derived from a common catalytic molecule. The study indicates the identity of the branching isoenzymes of Oscillatoria and Cyanidium, and lends further supporting evidence to the cyanophyte origin of the enigmatic alga.
Investigation on the Assimilation of Nitrogen by Maize Roots and the Transport of Some Major Nitrogen Compounds by Xylem Sap
Authors: IVANKO S. , INGVERSEN J. 
Published: April 2006

AbstractThe uptake and assimilation of nitrate and ammonia have been studied in Zea mays. Nitrogen‐starved maize roots are capable of accumulating a potential capacity for nitrogen uptake and assimilation. Reestablishment of nitrogen supply leads to intense uptake, reaching 154 % of the reference variant level after 24 hours when nitrate is supplied, and 121 % when ammonia is supplied. After 24 hours the insoluble nitrogen fraction accounts for 80, 54 and 55 % of the total taken up in the PK + NO3‐, PK + NH4+ and NPK variants respectively.
Interrelations between Gibberellic Acid, Cytokinins and Abscisic Acid in Retarding Leaf Senescence
Authors: BACK A. , RICHMOND AMOS E. 
Published: April 2006

AbstractThe interrelation between the effects of abscisic acid (ABA) and the effects of cytokinins and gibberellic acid in retarding leaf senescence was investigated. Leaf discs from plants of Taraxacum megallorrhizon, Rumex pulcber and Tropaeolum majus were floated on solutions of cytokinin or GA to which given amounts of ABA were added. After five days, chlorophyll was extracted and the amount estimated spectrophoto‐metrically. The interrelation between the effects of abscisic acid and cytokinins differed from that between the effects of ABA and gibberellic acid. Abscisic acid reduced the senescence retarding effect of GA more than that of cytokinins. A high concentration of cytokinins nullified the senescence enhancing effect of low concentrations of ABA. GA did not reverse the effects of ABA.
Autoradiographic Studies of Pear Pollen Tube Walls
Authors: ROGGEN H. P. , STANLEY R. G. 
Published: April 2006

AbstractGerminating pollen was supplied D‐glucose‐3H and myo‐inositol‐3H. Pollen tube growth was terminated at varying intervals and the cytoplasmic contents removed or left intact. Empty pollen tubes were treated with β‐1,4‐glucanase, β‐1,3‐glucanasc or pectinase and the residual radioactivity was determined. Analysis of autoradiograms showed the pollen tip contained primarily pectin, the subtending cell wall of the tube was primarily cellulose, or possibly hemi‐cellulose, and callose accumulated most heavily toward the rear, older segments of the tube. Callose was also heavily formed in the tip region of non‐growing tubes. Pectin formed from myoinositol appeared to be solubilized, or removed, from the wall to the cytoplasm with aging of the pollen tube.
Abscisic Acid As A Ribonuclease Promoter
Authors: LESHEM Y. 
Published: April 2006

AbstractBy means of experimentation with the barley endosperm system and with peroxidase isoenzyme production during culture of tobacco pith the mode of action of abscisic acid (ABA) was investigated. Gibberellic acid (GA3) promoted reducing sugar production was significantly inhibited by ABA and bovine pancreas ribonuclease (RNase), while the specific RNA polymerase inhibitor rifamycin was without effect. In tobacco pith culture, ABA promoted appearance of induced isoenzymes, the effect being completely checked by rifamycin. Furthermore ABA significantly inhibited, and GA3 promoted production of RNA in treated tobacco plants. It is suggested that the mode of ABA action in these systems may be an inductive one on the degradative enzyme, RNase, and not necessarily a negative one on the promotive RNA polymerase. This conclusion implies effect on some preexisting RNA, the breakdown of which is mediated by ABA‐activated RNase.
Die Wirkung einer Vorbestrahlung auf den Wuchsstoffgehalt von X‐2‐Pflanzen bei Brassica oleracea var. acephala Von
Authors: BRUGOVITZKY EDITH 
Published: April 2006

Abstract The Effect of Pre‐irradiation on the Content of Growth Substances in Xi‐Plants of Brassica oleracea var. acephala. The auxin content of growth stimulated young plants (Brassica oleraceav ar. acephala) of the X2‐generation, originating from X‐ray irradiated seeds (75 kR) was determined. Methanolic extracts were separated on thin‐layer‐chromatograms, which were analyzed by ultra‐violet light and various chemical reactions. Quantitative determinations of growth substances were made using the Avena‐coleoptile‐cylinder‐test. The following results were obtained: 1. X2‐plants had a higher content of IAN compared with unirradiated control samples; 2. IAAm was detectable in only two out of 40 experiments; 3. Two fluorescent substances were detected: a hydroxycinnarmc acid derivative and a long chained unsatu‐rated ketone or aldehyde, which is still unknown.
Changes of Starch Synthetase Activity of Cucumber Leaves during Ammonium Toxicity
Authors: MATSUMOTO H. , WAKIUCHI N. , TAKAHASHI E. 
Published: April 2006

AbstractThe changes of granule bound starch synthetase activity in cucumber leaves (Cucumis sativus L. cv. Suisei No. 2) were investigated during ammonium toxicity. Generally speaking the quantity of starch granules of injured plants were less than that of normal plants. ADPG is a more effective glucose donor to starch synthesis than UDPG. It was found that the starch synthetase activity of injured plants was decreased compared to the normal plants. This variation of enzyme activity was higher when UDPG was used as glucose donor. The addition of K+ and NH4+ generally inhibited the enzyme activity when UDPG was used as glucose donor, but stimulated it when ADPG was used. This stimulation was found to be more effective in enzymes prepared from injured plants than from normal plants. The level of potassium bound to starch granules was not changed markedly between normal and injured plants.
A Definition of Optimum Nutrient Requirements in Birch Seedlings. II
Authors: INGESTAD TORSTEN 
Published: April 2006

AbstractThe aim of the experiments described was to specify further the nutrient requirements of birch seedlings. A growth method is described in which the nutrients consumed at maximum growth of birch seedlings can be replaced, without change of the nutrient solution, by means of additions made as pH and conductivity titrations so that three conditions are satisfied: 1) All necessary mineral nutrients are present in the plant in optimum proportions. 2) The nitrogen sources NH4+ and NO3‐ are present in the nutrient solution in an optimum ratio. 3) Total concentration in the solution is optimum. The three conditions may be regarded as criteria in a definition of nutrient requirements. The possible use of criterion 1 as an expression of the optimum nutrient status is also discussed. A considerable increase in light intensity had no significant effect on the optimum nutrient proportions or the optimum total concentration. A tendency to lower ammonium uptake in relation to nitrate was induced when both nitrogen sources were present. Simple stock nutrient solution systems are listed and discussed.
Studies on the Germination of Pine Pollen (Pinus mugo) in vitro. III. Inhibition by D‐Mannose and Deoxyhexoses
Authors: NYGAARD PER 
Published: April 2006

AbstractD‐Mannose, 2‐deoxy‐D‐glucose, 6‐deoxy‐D‐galactose, and 2‐deoxy‐D‐galactose inhibit germination of pine pollen (Pinus mugo Turra) probably competitively with a metabolizable sugar. Inhibition by D‐mannose, 2‐deoxy‐D‐glucose, or 6‐deoxy‐D‐galactose is reversed by transfer of pollen to sucrose medium, if the inhibitors was added before tube growth has started. In contrast, inhibition by 2‐deoxy‐D‐galactose is irreversible except after very short exposures to the inhibitor, in which case the transfer results in reduced growth and germination.Incubation with 2‐deoxy‐D‐glucose, 6‐deoxy‐n‐galactose, or 2‐deoxy‐D‐galactose after tube growth has started, results in irreversible inhibition of growth. If D‐mannose is used, growth is resumed if the pollen are transferred to sucrose medium. Addition of D‐mannose or lowering of the temperature prior to incubation with the deoxyhexoses protected against the irreversible growth inhibition.Uptake of oxygen and 32P‐labelled phosphate is reduced upon addition of either of the inhibitors.
Variants of Myxococcus virescens Exhibiting Dispersed Growth. Growth and Production of Extracellular Enzymes and Slime
Authors: HASKÅ GUNO , STÅHL STEN 
Published: April 2006

AbstractThe growth of two strains of Myxococcus virescens exhibiting dispersed growth was followed in casamino acids (N III‐C) media and casitone media. The changes in optical density, pH, pigmentation as well as the secretion of bacteriolytic and proteolytic enzymes, DNA and polysaccharides during growth were recorded.In both media the bacteria grew exponentially with a generation time of 4 (casitone) and 20 hours (N III‐C) respectively. The maximal cell mass was about 4 times higher in casitone than in casamino acids media.The amounts of bacteriolytic enzymes produced by the two strains in N III‐C medium were different but in casitone medium they were about equal and considerably higher. The maximal values of proteolytic enzymes were about the same in both media and always occurred later than the bacteriolytic maxima. Both activity peaks appeared before the phase of decline.The polysaccharide production reached a maximum during the stationary growth phase in both media. A higher value was reached during growth in casitone medium than in N III‐C medium. During the phase of decline a second increase of polysaccharide in the medium appeared. No DNA could be detected in the cell‐free solutions until the beginning of the phase of decline.
Indole‐3‐Pyruvic Acid as an Intermediate in the Conversion of Tryptophan to Indole‐3‐Acetic Acid. I. Some Characteristics of Tryptophan Transaminase from Mung Bean Seedlings
Authors: TRUELSEN T. A. 
Published: April 2006

AbstractSeedlings of mung bean (Phaseolus aureus) contain a soluble enzyme capable of converting l‐tryptophan to indole‐3‐pyruvic acid by transamination. The concentration of the enzyme is highest in the stem meristem and primary leaves and lowest in the roots. The enzyme was purified 28.6 fold by ammonium sulphate precipitation, Sephadex G‐200 filtration, and electrophoresis. The isoelectric point of the enzyme protein was pH 6.6. The optimum pH and temperature for the catalytic conversion were ca. 8.5 and 53°C respectively. Using l‐tryptophan and α‐ketoglutarate as substrates Km was found to be 3.3 × 10−4 M and the activation energy 18,270 cal per mole. The enzyme converted only the l‐form of tryptophan, phenylalanine, tyrosine, and histidine. Out of 13 other l‐amino acids tested 8 could be transaminated. Eight α‐keto acids tested could all be used as substrates. High efficiency of an α‐keto acid as an amino group acceptor agreed usually with high efficiency of the corresponding amino acid as a donor. The pari ß‐methyl‐α‐ketoisovaleric acid and isoleucine was an exception to that rule. Addition of pyridoxalphosphate to the reaction mixture was not needed.The indole‐3‐pyruvic acid formed in the reaction was trapped and partly stabilized as its borate complex and measured spectrophotometrically at 327 nm. The keto acid formed was further identified by chromatography of its 2,4‐dinitrophenylhydrazone in 4 solvent systems. When using α‐keto‐glutaric acid as a substrate, the glutamic acid produced was determined by the glutamate dehydrogenase method. The sensitivity of the assay permits enzyme determinations in extracts from 5 mg leaves or 100 mg roots.
Effects of Growth Retardants on Norway Spruce (Picea abies)
Authors: DUNBERG ARNE , ELIASSON LENNART 
Published: April 2006

AbstractYoung seedlings of Picea abies Karst, grown in nutrient solution were treated with the growth retardants Amo‐1618, B‐995, and CCC. These were added to the nutrient medium. B‐995 and CCC retarded root and shoot growth in the concentrations 100, 10, and 1 mg/l. Growth was almost entirely inhibited by 300 mg/l, obviously due to toxicity. The effects of Amo‐1618 were similar but more varying. GA counteracted the effects of all the retardants on shoot growth, but not on root growth.
The Effects of Mercury Compounds on the Growth and Orientation of Cucumber Seedlings
Authors: PUERNER NORMA J. , SIEGEL SANFORD M. 
Published: April 2006

AbstractMercuric chloride alone, in admixture with fluorescein or chemically combined as mercurochrome inhibited cucumber growth and induced disorientation of root and shoot. The inhibitory effects of Hg‐ion were reduced but the disorienting (ageotropic) effects enhanced by the presence of fluorescein. In addition to mercury, nine other elements were tested at concentrations up to 100 mg/l (as metal ion). Disorientation was induced by Zn, Ag, Cd, In, Pt and Hg. Pb and Au were not toxic, but Ga and Tl were too inhibitory to permit disturbances in orientation.
Antigen‐Antibody Crossed Electrophoresis of Soluble Proteins in Different Strains of Spirulina
Authors: LINDBLOM MARIANNE 
Published: April 2006

AbstractSoluble proteins from three strains of the blue‐green alga Spirulina were compared by antigen‐antibody crossed electrophoresis. The three algal strains were shown to contain at least two immunologically identical proteins. Differences between all three strains were found among proteins with low electrophoretic mobility. Antigen‐antibody crossed electro‐phoresis is a very sensitive method and could be used as a complement to morphology and other characteristics when comparing different algal strains.
Spinach Chloroplast Membranes after Differential Lipid Extraction
Authors: YAO VIVIANA J. , STERLING CLARENCE , STOCKING C. RALPH 
Published: April 2006

AbstractChloroplasts from spinach were fixed in glutaraldehyde and extracted with three different lipid solvents, after which the lipid composition was analyzed. Studies were also made with the electron microscope. In cold dry acetone, which removes 75 % of lipids, the basic structure of the membranes is unchanged. Acetone with 10 % water removes 89 % of the lipids and a mixture of chloroform with methanol removes 93 % of the lipids, both solvents leaving nearly unrecognizable membrane structures. The relationship between lipid composition and membrane structure is discussed.
The Effect of Coumarin on Growth, Production of Dry Matter, Protein and Nucleic Acids in Roots of Maize and Wheat and the Interaction of Coumarin with Metabolic Inhibitors
Authors: SVENSSON SVEN‐BÖR JE 
Published: April 2006

AbstractEffects of coumarin on fresh weight, dry matter, protein and nucleic acid content per cell in attached roots of maize and wheat and in whole excised elongation zones of maize were determined. The inhibition in cell length exerted by coumarin did not correspond to an inhibition of the net synthetic capacity. Coumarin treatment increased the cell surface, the production of dry matter and the protein content per cell. The dry matter and the protein content per unit surface was slightly increased or unaffected. The effect of coumann on cell shape seemed to be independent of that on dry matter production and net protein synthesis. The same was found in excised elongation zones. —The net DNA‐synthesis per cell was slightly increased in attached roots by coumann treatment, but this effect was probably not correlated with the morphogenetic changes. Inhibition of DNA‐synthesis with hydroxyurea did not alter the coumarin induced changes in cell shape. —The net RNA‐synthesis per cell was slightly decreased after coumarin treatment, but the net RNA‐synthesis per cell and the morphogenetic effects exerted by coumarin were not related with each other. Inhibition of m‐RNA‐synthesis with actinomycin D did not prevent the effects of coumarin on cell division, cell expansion, dry matter production and net protein synthesis. The same was true for inhibitors of protein synthesis, puromycin and p‐fluorophenyl‐alanine. The findings are in support of the view that coumarin affects already existing structures or enzymes. —Comparisons between coumarin and the uncouplers, DNP and dicoumarol, showed that the effects of coumarin were not, solely, due to uncoupling. SH‐protecting agents, BAL, DTE and glutathione, did, with few exceptions, not reduce the morphogenetic effects of coumarin.
Effets du NaCl sur ľactivité de la nitrate réductase chez deux variétés halophiles: Suaeda maritima var. macrocar pa et var. flexilis
Authors: BOUCAUD JEAN 
Published: April 2006

AbstractThe nitrate reductase activity of Suaeda maritima var. macrocarpa and var. flexilis grown on nitrate‐rich substrates with 1 to 23 g/1 NaCl is maximum after 30 days of culturing.Compared to the substrate with the lowest salt content, the activity increase obtained with 7.5 g/1 of NaCl is greater in the more halophilous variety (var. macrocarpa). Even though the NaCl docs not operate directly on the induction and activity of nitrate reductase, it is responsible for this increase by modifying the CO2 assimilation and protein synthesis.
Inhibition of the Development of a Cation Accuniulatory System and of Tris‐induced Uptake in Storage Tissues by N6‐benzyladenine and Kinetin
Authors: VAN STEVENINCK R. F. M. 
Published: April 2006

AbstractThe effect of N6‐benzyladenine (BA) and kinetin on cation uptake in disks of beetroot (Beta vulgaris L.) and swede (Brassica napobrassica Mill.) tissue was measured in aerated solutions, containing 1 mM NaCl or 1 mM KCl, and in the presence or absence of trishydroxymethyl ammo methane (tris) buffer at pH 8. This investigation followed a suggestion that the immediate activation of cation uptake in freshly sliced beetroot disks by tris (the tris‐effect) may depend on stimulation of hexokinase activity. BA, a competitive inhibitor of hexokinase, caused a complete inhibition of tris stimulated cation uptake in beetroot disks, but the effect was delayed and preceded by a 3–4 hour period of promoted cation uptake. Generally, the effects of BA and kinetin were identical. Use of 14C‐kinetin indicated a rapid incorporation of kinetin into the tissue. BA and kinetin also prevented the development of a cation uptake capability during the aging of the beetroot disks. Swede disks which do not show a tris‐effcct and no lag phase in development of cation uptake capability were not affected by BA and kinetin treatments. Mechanisms of tris induced cation uptake are discussed with emphasis on its role as a proton acceptor.
Effect of Menadiol Disulfate on the Phylloquinone Content of Wheat (Triticum aestivum)
Authors: JANSSON OWE 
Published: April 2006

AbstractSeedlings of Triticum aestivum L. were sprayed with menadiol disulfate in water solution. Eight days after spraying, the content of phylloquinone in the shoots was more than twice as high as in shoots of untreated control plants. The application of menadiol disulfate caused a stimulation of the synthesis of phylloquinone. It is possible that menadiol is an intermediate in the biosynthesis of phylloquinone.
Entrainment of Geotropic Oscillations in Hypocotyls of Heliunthus annuus– An Experimental and Theoretical Investigation
Authors: ANDERSEN H. , JOHNSSON A. 
Published: April 2006

AbstractA theory for the geotropic movements of the Heliunthus unnuus hypocotyl has been given earlier by Johnsson et ul. In the present paper this theory is tested by extensive experiments. The magnitude as well as the rate of geotropic curvature are found to be in agreement with the theoretical predictions.Further, the geotropic reaction time, defined as the time between the start of geotropic stimulation and the start of the geotropic reaction is determined as a function of the stimulation angle with respect to the plumb line. A slight variation found in the reaction time is included in the theory.