bluuebunny/crossref_metadata_2025_split huggingface dataset:
Long and Short Term Development of Frost Hardiness in Pinus silvestris, and Heavy Particle Adenosine Triphosphatase
Authors: BERVAES J. C. A. M. , KYLIN A. 
Published: April 2006

AbstractThe effect of different growth temperatures, of transfer between them, and of changes in outside temperature on frost hardiness and ATPase activity of Scotch pines (Pinus silvestris L.) were studied.Plants which had been grown in the greenhouse and transported to outside “remembered” something of their earlier growing circumstances during a long period. They differed from the plants continuously grown outside in the level of hardiness, although changes in temperature caused similar fluctuations in the hardiness of both groups. It is evident that two mechanisms are present, the one causing a long term determination of the level of frost hardiness obtainable, the other causing a short term adaption.The heavy particle ATPase activity as investigated below 20°C grouped itself according to the main temperature groups of the experiment. Above 30°C, the pretreatments had given rise to differences within the temperature groups. The level of the ATPase activity increased as the growing season came closer.
Effect of Fatty Acids on the Activity of Bacteriolytic Enzymes
Authors: HASKÅ GUNO , NORÉN BÖRJE , ODHAM GÖRAN 
Published: April 2006

AbstractThe ability of fatty acids to sensitize gram‐negative and gram‐positive bacterial cells to the action of bacteriolytic enzymes was studied. By synergetic effects between bacteriolytic enzymes and fatty acids isolated from Myxococcus such bacteria, which were otherwise resistant to the enzymes, could be lysed. Isobranched and unbranched acids with 11–15 carbon atoms were active and could sensitize Bacillus megaterium and Aerobacter aerogenes to the action of bacteriolytic enzymes from myxobacteria and to lysozyme. The sensitizing activity of tetradecanoic acid was enhanced with increasing concentration even after the solution was saturated. Neither ethylene diaminetetraacetate (0.1 and 1 mM) nor Triton X‐100 (1 0/00) could sensitize resistant bacteria to the action of bacteriolytic enzymes. However, they were active in combination and they could also increase the effect of tetradecanoic acid.
Triterpeneglycosides as Inhibitors of Fungal Growth and Metabolism
Authors: OLSEN ROLF A. 
Published: April 2006

AbstractThe inhibitory effect of the triterpeneglycosides aescin and avenacin on growth capability, leakage of organic and inorganic substances, and uptake of potassium ions in Ophiobolus graminis and Neurospora crassa was antagonized by the cations Ca2+ and Mg2+, the former having the greatest effect. The effect was different in the two fungi and was influenced by the buffer system.
Conversion of Digalactosyl Diglyceride (Extra Long Carbon Chain Conjugates) into Monogalactosyl Diglyceride of Pine Needle Chloroplasts upon Dehardening
Authors: BERVAES J. C. A. M. , KUIPER P. J. C. , KYLIN A. 
Published: April 2006

AbstractChanges in lipid and fatty acid composition of pine needle chloroplasts were determined upon transfer of the trees from outside (‐5°C) to 32°C.Within 7 1/2 hours after transfer, conversion of a portion of digalactosyldiglyceride into monogalactosyl diglyceride was observed. This portion consisted of a conjugate with extra long chain fatty acids (cerotic acid, 26: 0, and C26‐cyclo‐propane fatty acid). Only minor further changes in lipid and fatty acid composition were observed. Dehardening of the needles occurred within the same period. The data support the hypothesis that the degalactosidation reaction specifically depends on the fatty acid composition.The extra long chain fatty acids may link different sub‐units of the chloroplasts and may contribute to an additional layer of H‐bonded water on the membrane surface because of the increased exposure of the galactose groups.
Evidence for the Transfer of Rhizobial Metabolites to the Polyploid Nuclei of Young Clover Nodules
Authors: BRUENING M. L. , WULLSTEIN L. H. 
Published: April 2006

AbstractAutoradiography was used to provide evidence for the transfer of Rhizobium produced moieties to the host nuclei of young clover nodule cells. Cells of Rhizobium trifolii Dangeard were labeled with 3H‐adenine or 4,5‐3H‐l‐leucine and 3,4‐3H‐l.‐proline, washed free of external label, and allowed to nodulate young seedlings of white clover (Trifolium repens L. cv. White Dutch). Sections (0.5–1.0 μm) of young nodules up to four days old were autoradiographed using the dipping technique. Grain counts indicated movement of tritium from the leucine‐proline labeled rhizobia to the polyploid nuclei of two day old clover nodule cells. Acetylene reduction was not detected until approximately 24 hours after the transfer of tritium was observed. No transfer of tritium was observed with 3H‐adenine labeled rhizobia. It is hypothesized that nodulating rhizobia may induce clover nodule cells to initiate leghemoglobin synthesis by the transfer of a bacterially produced inducer.
Shoot Growth and Mineral Composition of Leaves and Fruits of Apple as Affected by Relative Air Humidity
Authors: TROMP J. , OELE J. 
Published: April 2006

AbstractShoot growth and water consumption of potted Golden Delicious trees were studied under a controlled environment with respect to two lewels of air humidity, soil moisture content, and the availability of nitrogen. In the high‐N treatment, high air humidity and high soil moisture content promoted growth; at the low‐N level, growth did not respond to the treatments. Water consumption was enhanced at low air humidity but was not afiected by the moisture centent of the soil.In potted fruit&earing Cox's Orange Pippin trees exposed to two levels of air humidity, low humidity reduced shoot growth and, but to a much lower degree, fruit growth. It increased rhe spur‐leaf levels of N, Mg, and, for part of the experimental period, K and Ca, but affected hardly the mineral level in fruits. It is concluded that the amount of the minerals reaching the fruit is determined by the relative im‐portance of the xylem influx during the first few weeks after fruit set and the phloem influx occurring throughout. It is suggested that the xylem supply of the various minerals does not differ greatly; it is probably the main way for the influx of Ca, but for N, K, Mg, and P the phloem influx is com‐pletely dominating.
Reversal by Mercaptoethanol of Protective Effect of Solutes Against Frost Injury of Red Cabbage
Authors: KRULL EDWARD , LEVITT J. 
Published: April 2006

AbstractIn confirmation of Maximov's earlier results, non‐penetrating (sucrose) and penetrating (dimethylsulfoxide) substances lowered the frost killing temperature from ‐6°C in the control to ‐11° to ‐24°C, depending on the concentration. In contrast to his results, neither glycerol nor CaCl2 provided as good or as consistent protection.The addition of 0.05 M mercaptoethanol overcame this protective effect either completely (low concentrations of protectant) or partially (high concentrations). The effect of the mercaptoethanol occurs during freezing and not during thawing. Since ethanol, without the mercapto‐(SH) group, does not counteract the protective effect, such protection must be related in some way to the sulfhydryl group — perhaps by an effect on the disulfide and sulfhydryl groups of the proteins.
The Effect of Gravity Compensation on Growth and Cell Wall‐loosening Enzymes in Helianthus annuus Hypocotyls
Authors: BARA METIN , GORDON SOLON A. 
Published: April 2006

AbstractThe effect of gravity compensation by the clinostat on the elongation, weight, and activity of two cell wall‐loosening enzymes (cellulase and β‐1,3‐glucanase) in Helianthus annuus hypocotyls was examined. Gravity compensation increases elongation (28.1 %) and weight (18.3 %). The activity of cellulase extracted from the apical sections is raised, but there is no significant effect on β‐1,3‐glucanase. The relationship between gravity compensation, changes in auxin level, and function of these two enzymes in respect to elongation is discussed.
Regulators of Cell Division in Plant Tissues XIV. The Cytokinin Activities and Metabolism of 6‐Acylaminopurines
Authors: LETHAM D. S. , PARKER C. W. , GORDON M. E. 
Published: April 2006

AbstractCertain 6‐acylaminopurines have been shown to exhibit activity in several cytokinin bioassays. The active compunds included 6‐N,2′‐O‐dibutyryladenosine 3’:5′‐cyclic monophosphate, but adenosine 3′:5′‐cyclic monophosphate was inactive. The metabolites formed from [2,8‐3H] 6‐benzoylaminopurine by radish seedlings and excised radish cotyledons were investigated. When compared with zeatin, this amide showed considerable stability in vivo. Conversion to 6‐benzylaminopurine and its riboside was not detected but slight degradation to adenine was indicated. The principal metabolite was an unidentified compund.
Induction of Salt Sensitivity in Ophiostoma and Its Reversal by Imidazole Derivatives
Authors: FRIES NILS 
Published: April 2006

AbstractCells of the ascomycete Ophiostoma multiannulatum became sensitive to inorganic salts after a heat shock or a treatment with 2,4‐dinitrophenol. The induced sensitivity to chloride and bromide ions could be largely reversed by histidine and certain other imidazole derivatives. No other organic compounds tested except imidazoles possessed this ability. The sensitization is interpreted as a consequence of an injury to cellular membranes, in particular those of the mitochondria, and to an impaired oxidative phosphorylation.
Uptake of Uracil by Synchronous Chlorella fusca
Authors: KNUTSEN GJERT 
Published: April 2006

AbstractUptake of radioactive uracil by light‐dark synchronized Cblorella fusca Shihira and Krauss was studied. For the characterization of the uptake system autospores were used and the following results obtained. Autospores kept in the dark accumulated uracil against a concentration gradient in a process having an observed activation energy of 10 keal/mol in the 10–40°C interval. Addition of glucose to the reaction suspension did not affect the uptake, but, 100 γM dinitrophenol inhibited the process by 90%. Abrupt changes in rate were found upon changing the conditions from light to dark and vice versa, and the rates measured in light were about 2.5 times larger than those found in the dark.Initial rates measured in the dark followed saturation kineties with half maximal rate found at 0.25 γM uracil, and with an apparent maximal rate of 1.7.10‐10 mol/10 min . 107 cells.The effect of 14 pyrimidines on uptake was tested, and it was found that uracils which were substituted in the 5′ or 5′+ 6′ positions were strongly inhibitory. Of these, thymine and dihydrouracil were tested and shown to inhibit uracil uptake competitively.Initial uptake rates, measured in the dark with 1.0 γM uracil, were recorded at intervals during the 24 h synchronous cycle. The uptake rate per ml culture was constant during the first 9 h, thereafter increasing to reach a peak value at 14 h. This peak was followed by a strong increase from 18 h onwards, this increase being concomitant with the sporulation process, and closely followed its time course.
Influence of Light of Different Spectral Compositions on Growth and Metabolism of Citrus Seedlings
Authors: ERNER Y. , GOREN R. , MONSELISE S. P. 
Published: April 2006

AbstractSour orange (Citrus aurantium L.) seedlings grown for six months under covers transmitting light of different spectral composition, were compared with others grown under a white cover (control) and outside in full daylight. The intensity of transmitted light was equalized under all covers and attained only 20% of full daylight.Seedlings grown in daylight were shorter, had more internodes, smaller leaves, less chlorophyll and more ascorbic acid than the others.Blue + far‐red covers (no transmission between 560–700 nm) enhanced seedling length, the protein and chlorophyll content and peroxidase activity of leaves. When also the wave‐range above 700 nm was cut out (blue) seedlings were the shortest, and leaves had very high protein and chlorophyll content, but much less ascorbic acid and lower peroxidase activity. Red + far‐red covers (no transmission below 500 nm) enhanced seedling length more than blue + far‐red; leaves contained as much protein as control, but had relatively high chlorophyll and peroxidase activity. Ascorbic acid was as low as in blue light.
Organic Nutrients in the Media for Propagation of Cymbidium in vitro
Authors: FONNESBECH MOGENS 
Published: April 2006

AbstractProtocorms of Cymbidium (Orchidaceae) were grown on media containing different organic nutrients. Of the sugars tested sucrose was better than maltose, glucose and fructose, and sucrose had an optimum concentration of 3 to 4 %. D‐Mannose was significantly less effective than the other sugars. The amino acid mixtures casamino acids (casein hydrolysate) and tryptone increased growth while yeast extract was inhibitory and malt extract without effect. Optimal concentrations were 2 to 3 g · l‐1 casamino acids and 3 to 4 g · l‐1 tryptone. It was to some extent possible to substitute the amino acid mixtures with a single amino acid (glutamine at 300 mg · l‐1). Arginine was inhibitory and asparagine was without any effect. Vitamins proved to be unnecessary although there was a tendency towards increased growth with nicotinic acid and meso‐inositol. Purines and pyrimidines were added to the medium but with no effect. Liquid endosperm from coconuts (10 to 15%) increased growth while the liquid endosperm from Aesculus hippocastanum was inhibitory. On the basis of these results a revised medium is proposed for the in vitro propagation of Cymbidium.
Content and Aggregation of Ribosomes during Formation, Dormancy and Sprouting of Tubers of Helianthus tuberosus
Authors: BAGNI NELLO , DONINI ARNALDO , FRACASSINI DONATELLA SERAFINI 
Published: April 2006

AbstractThe ribosomes and their qualitative (monosomes‐polysomes) and quantitative variations over a whole vegetative period of the tuber of Helianthus tuberosus L. (cv. OB 1) were examined. Tubers in different phases of growth, dormancy and sprouting or slices of dormant tubers activated with 2 x 10‐6M indol‐3‐acetic acid were used. The ribosomes were analyzed by a linear sucrose gradient.During flowering, polysomes of tuber disappeared almost completely and rRNA decreased in comparison with the level present at the beginning of tuber formation. After flowering, there was a new synthesis of monosomes and polysomes until the onset of dormancy; this last period was characterized by a marked increase in polysomes and a proportional increase in monosomes. The level remained almost constant till the break of dormancy. When the tubers sprouted, ribosomes, present almost exclusively as monosomes, decreased considerably; on the contrary the non‐photosynthetic sprouts contained many monosomes and polysomes.The first phases of activation (3 h) of tuber slices were characterized by a RNA synthesis, which occurred during one hour, in the subunit region of the gradient. Successively (10 h of activation) the 32P incorporation was seen also in the polysome region and increased with time. Some possible interpretations of these last results are discussed.
Titration of Photophosphorylation in Spinach Chloroplasts with 3‐(3,4‐dichlorophenyl)‐1,1‐dimethylurea (DCMU)
Authors: SUNDBERG I. , KYLIN A. 
Published: April 2006

AbstractThe kinetics of the inhibition of photophosphorylation in chloroplasts from spinach (Spinacia oleracea) was investigated with 3‐(3,4‐dichlorophenyl)‐1,1‐dimethylurea (DCMU) in small concentration intervals, starting at 10‐7M. Plots of the reciprocal of photophosphorylation against concentration of DCMU gave essentially the same straight line with 2 mM nicotinamide adenine dinucleotide phosphate (NADP) together with saturating amounts of ferredoxin or with 4 mM K3Fe(CN)6 as the final acceptors for electrons. Practically complete inhibition was obtained at 3 x 10‐6M DCMU. With 0.1 mM flavin mononucleotide (FMN) and ferredoxin, the inhibition between 10‐7M and 10‐6M DCMU was a little slower than in the other two cases. At 10‐6M DCMU a break occurred to a new straight line in the plots, indicating that another reaction was inhibited. Total photophosphorylation without DCMU was about 77 μmol ATP per mg chlorophyll and hour. At the breaking point 20% remained, and inhibition was not complete even at 8 x 10‐6M DCMU. The inhibitor constant for the high‐DCMU reaction was in the order of 2 x 10‐5M; for the low‐DCMU reaction some complication made the “constant” appear negative. With phenazine methosulfate (PMS) added, DCMU was without effect on photophosphorylation. – As earlier shown by us, titration curves for intact cells of the microalga Scenedesmus show the break at 10‐6M DCMU; and above 6 x 10‐6M photophosphorylation in the algae is not further decreased by DCMU. The data are compared and their possible significance is discussed.
The Effects of Some Chelating Agents and Their Copper Complexes on Photosynthesis in Scenedesmus quadricauda
Authors: FÄNGSTRÖM INGEGERD 
Published: April 2006

AbstractThe effects on apparent photosynthesis in the green alga Scenedesmus quadricauda of four chelating substances, 8‐hydroxyquinoline (= oxine), β‐isopropyltropolone (=β‐thujaplicin), sodium dimethyldithiocarbamate and 3‐(β‐hydroxyethyl)‐C‐pentamethylene‐3‐aza‐dithiocarbamate have been investigated. The first three compounds mentioned had all an inhibitory effect on photosynthesis, measured as oxygen production with a manometric, a volumetric or a polarographic method. In combination with certain concentrations of CuSO4 bimodal dose response curves were observed, similar to those obtained on the growth of different microorganisms. Calculations of the amounts of different complexes that appeared in the nutrient solutions during the experiments are compared with the recorded degrees of inhibition. The results strongly indicate that the 1: 1‐complexes between Cu2+ and the chelating substances are the most toxic agents at low concentrations of these compounds.
Mechanisms of Sodium and Rubidium Uptake by Excised Barley Roots
Authors: NEUMANN‐GANMORE RUTH , WAISEL Y. 
Published: April 2006

AbstractAccumulation of sodium and rubidium by excised barley roots was investigated. The concentration isotherm yielded one absorption shoulder. Nevertheless, it is suggested that two mechanisms take part in the uptake of sodium and rubidium: One non‐metabolic mechanism with an apparent participation at low external salt concentrations (< 1 mM) and at high concentrations (> 20 mM). Such a mechanism is almost unaffected by low temperature conditions and by metabolic inhibitors. Rubidium possesses a high affinity toward this non‐metabolic system. The second mechanism is sensitive to metabolic inhibitors and to low temperature conditions. It dominates at intermediate external concentrations (1–20 mM). Sodium possesses high affinity towards this mechanism. The two mechanisms operate in a parallel manner beyond a diffusion barrier (= plasmamembrane) surrounding the cells. It is assumed that both the metabolic and the non‐metabolic mechanisms operate in the entire concentration spectrum, but their relative contribution to the total uptake varies at different ranges.
Effects of Inhibitors of Protein and Nucleic Acid Synthesis on the Development of Ion Uptake Mechanisms in Beetroot Slices (Beta vulgaris)
Authors: VAN STEVENINCK R. F. M. , VAN STEVENINCK M. E. 
Published: April 2006

AbstractMechanisms for the uptake of K+, Na+ and Cl‐ develop sequentially in thin slices of beetroot tissue washed under aerobic conditions. Actinomycin D inhibited or prevented the development of K+, Na+ and Cl‐ uptake mechanisms when added to freshly cut slices, but had no effect on net ion uptake when added after the development of the ion uptake mechanisms. The use of puromycin as a specific inhibitor of protein synthesis was unsatisfactory as it caused leakage of pigments and excessive loss of ions from the disks.Cycloheximide prevented the development of ion uptake mechanisms when added at the start of the experiment, but when added after the development of ion uptake mechanisms its inhibitory effect did not become apparent until after a certain time interval which varied from 3 hours for Cl‐ to 25 hours for K+ uptake in the same experiment. p‐Fluorophenylalanine caused an appreciable shortening of the time required for the development of Na+ and K+ uptake capabilities, while it completely prevented the development of a Cl‐ uptake mechanism. p‐Fluorophenylalanine‐induced early uptake of Na+ and K+, however, was followed by periods of net leakage of these ions.It is suggested that the development of ion uptake mechanisms depends on the production of m‐RNA, which appears to be relatively stable after its synthesis. The synthesis and decay characteristics of specific proteins required for the ion uptake mechanisms appear to differ for each ion species.
Regeneration in Streptocarpus Leaf Discs and its Regulation by Temperature and Growth Substances
Authors: APPELGREN MAIGULL , HEIDE OLA M. 
Published: April 2006

AbstractThe formation of adventitious buds and roots in leaf discs of Streptocarpus x bybridus‘Constant Nymph’ were both stimulated by relatively low temperatures (12 and 18°C) applied to isolated discs or to the growing plants before leaf harvest.Auxins also promoted both bud and root formation, the optimum concentration for rooting always being one to two orders of magnitude higher than the optimum for budding. Cytokinins had only a small stimulatory effect on bud formation. At higher concentrations it was inhibitory and even counteracted the stimulatory effect of auxin on bud formation. As usual, root formation was inhibited by cytokinin.GA3 inhibited both bud and root formation but the inhibition was reversible by auxin. In presence of optimum auxin levels abscisic acid enhanced bud formation. It had little effect on root formation except for an inhibition at high concentrations.The effects of exogenous auxin and cytokinin suggest that Streptocarpus leaves have a high and non‐limiting level of endogenous cytokinin with auxin as the limiting factor for both root and bud formation. This would also explain the exceptionally high regeneration ability of this plant.