bluuebunny/crossref_metadata_2025_split huggingface dataset:
Growth‐Factors and Nucleic Acid Synthesis in Helianthus tuberosus
Authors: BAGNI N. , CORSINI E. , FRACASSINI D. SERAFINI 
Published: April 2006

AbstractThe study of the physiological significance of polyamines in higher plants has induced us to examine both the relationship between these compounds with indol‐3yl‐acetic acid (IAA) and the site of action of polyamines in the cell.Slices of dormant tubers of Helianthus tuberosus were activated with water, 2 × 10‐6M IAA, 10‐4M spermidine and two different concentrations of actinomycin D alone and with spermidine.The RNA synthesis caused by spermidine was similar to that caused by IAA. These data agreed with the hypothesis that the nucleic acid synthesis caused by IAA could be mediated by polyamine synthesis previously observed.Besides 10‐4M spermidine removed the inhibition of 1.5 × 10‐6M actinomycin D on nucleic acid synthesis. As the interaction necessarily occurs between spermidine and actinomycin at the DNA level, it therefore was possible to demonstrate that the primary site of action of spermidine in protein synthesis might occur on DNA also in vivo.
Nitrogen and Carbohydrate Metabolism of Japanese Mint as Affected by Phosphorus Deficiency and Seasonal Variations
Authors: SINGH D. P. , SINGH J. N. 
Published: April 2006

AbstractThe paper presents effects of phosphorus deficiency and seasonal variations on nitrogen and carbohydrate metabolism of Japanese mint (Mentha arvensis L. var. piperascens, Holmes). Mint plants were grown in sand cultures under full nutrition and under phosphorus deficiency conditions during winter and summer. Various nitrogen and sugar fractions were determined in the component parts at specified periods of growth stages. Phosphorus deficiency disturbed the nitrogen metabolism at the stages for amide and amino acid formation, which resulted in an accumulation of carbohydrates. The content of total soluble and total nitrogen was higher and that of insoluble nitrogen was lower in summer as compared with winter plants. Of the soluble fractions, the ammonia, amide and nitrate nitrogen were higher and the ‘rest’ nitrogen lower in winter plants. Nitrate formed the highest bulk of the pool of soluble nitrogen in winter, whereas in summer ‘rest’ nitrogen was most abundant. The content of total sugar in winter plants far exceeded that of summer plants, which was wholly due to increase in sucrose content. Glucose was the predominant reducing sugar in both seasons. However, the summer plants were richer in glucose than those from the winter.
Transpiration in Three Eucalyptus Species as a Function of Solar Energy, Soil Moisture and Leaf Area
Authors: GINDEL I. 
Published: April 2006

AbstractThree Eucalyptus species indigenous to Australia and successfully acclimatised in the subtropical and northern desert regions of Israel have been grown in pots. Two of them, which contained loess‐like desert soil, and one, which contained sandy soil, out of doors, have been exposed to extreme semi‐arid climatic conditions with only soil moisture under control. In each species one group has been kept at 15.5% and a second at 7% moisture. The groups grown in water deficient soil had a 31.0–42.8% smaller leaf area and a 2–4 fold lower transpiration rate, the values varying with species. When soil moisture was raised to the same level for the water deficient groups and the plants grown at field capacity an equal or a higher transpiration rate was obtained. This happened although both groups had been exposed to the same intensity of solar radiation and in spite of the significantly smaller leaf area in the groups grown in water deficient soil. In woody xerophytes grown in water deficient soil under arid conditions, the quantity of available soil moisture and the inherent biological properties of the species decide the rate of transpiration and not the area of the foliage or the intensity of solar radiation, or physical evaporation.
Role of Ascorbic Acid in Bud Development
Authors: JOHNNYKUTTY A. T. , KHUDAIRI A. K. 
Published: April 2006

AbstractAscorbic acid was found to increase bud development in Pisum sativum L. The interactions of ascorbic acid with indole‐3‐acetic acid, kinetin and gibberellic acid were studied. It was found that ascorbic acid promoted bud growth and overcame the inhibitory effect of auxin. When applied with gibberellin, bud growth was greatly enhanced. Ascorbic acid promoted bud development in red light only; it did not in far‐red or dark.
Influence of Age and Light on the Distribution and Development of Nitrate Reductase in Greening Barley Leaves
Authors: JORDAN W. R. , HUFFAKER R. C. 
Published: April 2006

AbstractThe relation between leaf age and the induction of nitrate reductase activity by continuous and intermittent light was studied with barley seedlings (Hordeum vulgare L. cv. Club Mariout). In general, nitrate reductase activity declined as the period of growth in darkness was extended beyond 5 days. Maximum activity was found near the leaf tip while activity was lowest in the morphologically youngest tissue near the base of the lamina. Increased activity was observed after continuous illumination of dark‐grown seedlings for 24 hours. The increase in activity in response to light was greatly reduced when the dark pretreatment period was extended beyond 8 days. The amount of nitrate reductase activity present in the different sections of the leaf was closely related to the amount of polyribosomes present. The pattern of chlorophyll accumulation closely parallelled that of increases in nitrate reductase activity.The initial lag in the induction of nitrate reductase activity was removed by a 10‐minute light treatment 6 hours before placing dark‐grown barley seedlings in light. The enzyme was also induced under flashing light with various dark intervals. These induction curves closely resembled those of chlorophyll accumulation under the same conditions.The development of photosynthetic CO2 fixation follows the same induction pattern in this system. Our results suggest that photosynthetic products may be required for the induction of significant levels of nitrate reductase activity in leaves of dark‐grown seedlings, although other light effects may not be discounted.
The Nature of Root‐Promoting Substances in Lycopersicon esculentum Seedlings
Authors: AUNG L. H. 
Published: April 2006

AbstractDetermination of the organ sites and chemical nature of root‐promoting substances in Lycopersicon esculentum seedlings was made. Results of organ excision indicated that the young cotyledons were the primary site of root‐promoting substances. As the cotyledon matured, its root‐promoting activity decreased while that of the developing plumular leaves increased. Application of 2,3,5‐triiodobenzoic acid (TIBA) at 10−3 M in lanolin to the hypocotyl below the cotyledonary node significantly prevented root formation. Bioassay, using a new tomato rooting test, of the basic, acidic and bound fractions of the cotyledon extracts after paper chromatography showed biological activities in all three fractions. Gas‐liquid chromatography of selected active regions of the paper chromatogram resulted in a partial tentative identification of indolepropionic acid, 5‐methylindole, 5‐hydroxy‐indole and 3‐indoleacetonitrile. The combined evidence indicated that the root‐promoting substances in tomato seedlings resemble auxin compounds.
Effects of Selected Herbicides on Plant Protoplasts
Authors: BOULWARE MARGARET A. , CAMPER N. DWIGHT 
Published: April 2006

AbstractPlant protoplasts were released from immature tomato fruits by incubation with a 20% solution of polygalacturonase (Pectinol R‐10, Rhom & Haas) dissolved in 0.1 M KCl + 0.1 M MgCl2. In this salt solution the protoplasts remained stabilized for up to 8 h and were used as a source of exposed plasma membrane. Gross responses of protoplasts to selected chemicals and herbicides were recorded photomicroscopically.Paraquat (1,1′‐dimethyl‐4,4′‐bipyridinium ion) treatments resulted in a characteristic response which was different from that of general denaturants (trichloroacetic acid, ethanol, and detergents) and of osmotic shock. Initial phases of the paraquat response were characterized by a segregation of the cytoplasm into isolated areas on the inner membrane surface. The final phase was a rupture of the plasma membrane and collapse of the cell.The herbicides, 2,4′‐dinitro‐4‐trifluoromethyl‐diphenylether (preforan); 1,1‐dimethyl‐3‐(α,α,α‐trifluoro‐m‐tolyl)urea (fluometuron); 3‐(3‐chloro‐4‐bromophenyl)‐1‐methoxy‐1‐methylurea (chlorbromuron); and α,α,α‐trifluoro‐2,6‐dinitro‐N‐N‐dipropyl‐p‐toluidine (trifluralin) produced no apparent structural effect on the protoplasts.
Effects of Abscisic Acid and its Esters on Stomatal Aperture and the Transpiration Ratio
Authors: JONES RUTH J. , MANSFIELD T. A. 
Published: April 2006

AbstractA single surface application of abscisic acid or its methyl and phenyl esters suppressed stomatal opening on leaves of Xanthium strumarium. The effect was restricted to the treated parts of the leaf blades, there being no detectable translocation to untreated parts. There were no increases in CO2 compensation to which stomatal closure could be attributed.Abscisic acid and its esters acted successfully as antitranspirants when applied once to leaf surfaces of young barley plants. Over a 9‐day period there was a reduction of about 50% in the amount of water transpired without any detectable reduction in the rate of dry weight increase. The treatments reduced transpiration relatively more than dry matter accumulation, and hence there was an increase in the water use efficiency. The effect of the treatments became progressively less over 9 days, but even at the end of the experiment (day 9) both the esters reduced transpiration by 20–25%. The esters were slightly more effective than abscisic acid itself.On the basis of the data presented here, field trials of the antitranspirant properties of these compounds are recommended.
The Selective Effect of Abscisic Acid on Ribonucleic Acid Components
Authors: LESHEM Y. , SCHWARZ LEAH 
Published: April 2006

AbstractAs determined by methylated albumin kieselguhr (MAK) fractionation, GA3 (gibberellic acid) significantly increased and ABA (abscisic acid) decreased RNA levels. In the case of ABA this effect was selective, the ribosomal RNA manifesting the typical decrease; while the sRNA peak was markedly increased. The pattern of labelled uridine incorporation into RNA resembles the MAK absorbancy profile and here as well, ABA although causing an overall decrease, increases labelling in the sRNA peak. The results are interpreted as a possible selective effect of ABA or alternatively as an accumulation in the sRNA peak of rRNA breakdown products. From in vitro experiments it was furthermore evident that ABA mediated RNA hydrolysis probably does not involve a direct activation of RNase by ABA. The in vivo effect would probably be devious.
Aphanizomenon flos‐aquae: Infection by Cyanophages
Authors: GRANHALL ULF 
Published: April 2006

AbstractThis report presents electron microscopic observations of a virus infection of Aphanizomenon flos‐aquae (L.) Ralfs and investigations on the presence of the causative cyanophage in a moderately eutrophic lake. The results indicate that the cyanophages regulate termination of the water‐bloom of this alga.
Growth of Variants of Myxococcus virescens
Authors: STÄHL STEN 
Published: April 2006

AbstractSome observations on variant strains of Myxococcus virescens B2 with special emphasis on characteristics associated with the ability to grow in dispersion are reported. The isolated strains were divided into two major classes according to their mode of growth in shaken and static liquid cultures based on casitone and casamino acids media. Strains growing in dispersion were designated D+‐strains and those growing in aggregates or as films, D−‐strains.Colony morphology, cell morphology, growth in liquid and on solid medium and morphogenesis were compared. The ability to grow in dispersion shown by D+‐strains seemed to be associated with a smooth colony on casitone agar, inability to form typical fruiting bodies and a low linear growth rate of colonies on solid medium as compared with the D−‐strains. In contrast D−‐strains produced rough colonies on casitone agar, were able to fruit and evidently formed an adhesive slime in the form of fibrils extending from the cell surface.It is suggested that the observed differences depend on different envelopes of the cells in the two classes.
Properties of the Invertases of Cultured Sycamore Cells and Changes in Their Activity during Culture Growth
Authors: COPPING LEONARD G. , STREET H. E. 
Published: April 2006

AbstractWhen cultured sycamore cells are homogenised in a phosphate‐citrate buffer at pH 7.0 and the homogenate centrifuged two fractions are obtained both of which show the presence of an acid (opt. pH 4.0–4.5) and a neutral (opt. pH 7.0–7.4) invertase. The activity of the insoluble pellet appears to be located in its cell wall fragments. The acid and neutral invertases of the soluble fraction can be separated by fractional precipitation with (NH4SO4.The activities of these enzymes are low in stationary phase cells but they increase following subculture to reach peaks of activity towards the end of the period of most active cell growth and division and then decline again as the cells begin to enter stationary phase. The activities of both enzymes are higher in the cell wall than in the soluble fraction and the acid invertase reaches higher levels of activity than the neutral enzyme in both fractions.When cells are subcultured there occurs within a few hours an increase in the acid invertase and a decline in the neutral invertase activity in the cell wall fraction and a decline in the acid invertase of the soluble fraction prior to the large net increases in the activities of both enzymes in both locations which occurs as the cells embark upon cell division.The pattern of changes in the invertase activities through the growth cycle of batch propagated cultures is similar whether the cells are grown in sucrose, or glucose, or sucrose plus glucose; the highest levels of activities were recorded in the glucose‐grown cells.The total yield of invertase activities and the distribution of activities between the soluble and cell wall fractions of the homogenates are affected by the pH of the extraction medium (within the range pH 4.0–8.0). It has not proved possible to completely remove the invertases from the cell wall fraction; upwards of 50 % of the acid invertase was recovered from this fraction by treatment with Triton‐X followed by urea, but these treatments inactivated a high proportion of the neutral enzyme.These findings are compared with other studies on the activity and intra‐cellular distribution of plant invertases and the possible roles of these enzymes discussed.
Wall‐bound Invertase Activity in Convolvulus Callus: Increase after Subculturing, and Paradoxical Effects of Actinomycin D, Cycloheximide, and Thienylalanine
Authors: KLIS F. M. , HAK A. 
Published: April 2006

AbstractThe wall‐bound invertase activity increased 3.3‐fold upon transfer of fragments of Convolvulus callus to fresh solid nutrient medium and 7.7‐fold upon transfer to liquid nutrient medium. Addition of actinomycin D, cycloheximide or the amino acid analogue thienylalanine brought about a further stimulation of the invertase content of the cell walls. The rise of wall‐bound invertase activity was not due to redistribution of invertase activity between cytoplasm and cell walls, and appeared to be dependent on metabolic energy.An equation is presented to calculate the half‐life of enzymes from their time‐course. Applied on the time‐courses of wall‐bound invertase activity, a half‐life of about 12 h was obtained in callus transferred to fresh solid medium and of about 5.4 h in tissue transferred to liquid medium. It is argued that the increase of invertase content of the cell walls is due to an enhanced rate of invertase synthesis.
Adaptive Biosynthesis of Thiazole and Bypassing of the Thiazole Requirement in Exobasidium by Acetyl Phosphate, Tween and Ethanol
Authors: SUNDSTRÖM KARL‐RAGNAR 
Published: April 2006

AbstractThe tested strain of Exobasidium vaccinii (Fuck.) Woron. required thiamine or its two moieties, thiazole and pyrimidine, for good growth. When grown on pyrimidine medium, rapid growth or thiazole synthesis appears after 600–1000 hours. As methionine, a supposed precursor in the biosynthesis of thiazole, stimulates this inductive growth, the influence of methionine precursors or metabolites stimulating methionine synthesis were tested for their ability to shorten the lag phase of E. vaccinii cultured on a thiamine‐deficient synthetic medium. None of the tested methionine precursors replaced methionine or significantly stimulated the inductive growth. This result does not exclude acetylhomoserine as a central metabolite in methionine synthesis.Acetyl phosphate, alcohols and the fatty acids of Tween, possible deliverers of the active acetyl groups, induced growth in thiamine‐free media. This growth seems to be possible by utilization of the compounds through a metabolic pathway not requiring thiamine. No evidence for participation of the glyoxylate cycle was found.
Rhizomorph Formation in Fungi I. Stimulation by Ethanol and Acetate and Inhibition by Disul‐firam of Growth and Rhizomorph Formation in Armillaria mellea
Authors: SORTKJÆR O. , ALLERMANN K. 
Published: April 2006

AbstractRhizomorph formation in Armillaria mellea (Vahl ex Fr.) Quél. has been studied on a synthetic glucose medium with ethanol and acetate as inducers. Disulfiram (antabuse) inhibited growth and rhizomorph formation when ethanol was the inducer, while the stimulating effect of acetate was unaffected. This indicates that ethanol is metabolised by the normal pathway via acetate.Growth, ethanol‐ and glucose uptake were measured as a function of time. Ethanol was used up in 12 days; after that, growth and glucose uptake declined. A further supply of ethanol gave a significant increase in the growth rate. The results show that ethanol is a limiting growth factor during the entire growth period.
Correlative Changes in Phytohormones in Relation to Senescence Processes in Rose Petals
Authors: MAYAK S. , HALEVY A. H. , KATZ M. 
Published: April 2006

AbstractA comparative study of the level of abscisic acid (ABA) and cytokinin and of ethylene production by rose (Rosa sp.) petals of the short‐lived cultivar Golden Wave (Dr. Verhage) and the long‐lived cultivar Lovita was conducted. In both cultivars, the level of ABA increased as the flowers aged; it was higher in Golden Wave in all developmental stages tested.Ethylene production by cut flowers of the two cuitivars remained low for a short time concomitant with development and then increased sharply. The rise in ethylene production occurred after 3 and 4 days in Golden Wave and Lovita, respectively. Cytokinin level increased as the flower started to open and then decreased to a low level. The significance of these changes in relation to maturation and senescence of rose petals is discussed.
The Effect of Light on Tobacco Mosaic Virus (TMV) Formation
Authors: OLSSON R. 
Published: April 2006

AbstractDiscs were punched from TMV‐inoculated tobacco leaves (Nicotiana tabacumL.) and illuminated while floating on half strength Vickery's solution maintained at 24°C. After 48 hours some discs were placed in the dark for 24 hours and the amount of TMV formed in the light and dark compared. Discs from young leaves formed more virus in the light than in the dark. Discs from older leaves produced less virus, but as much in the dark as in the light.
Effects of Ammonium and Potassium Ions on Some Physiological and Biochemical Processes of Excised Cucumber Cotyledons
Authors: PATNAIK RABINDRANATH , BARKER ALLEN V. , MAYNARD DONALD N. 
Published: April 2006

AbstractIncubation of excised cucumber cotyledons (Cucumis sativus L.) with NH4Cl solutions exceeding 0.001 M inhibited their greening, fresh weight increases, and incorporation of 14C‐leucine into insoluble N compounds. The absorption of 14C‐leucine during incubation and retention of moisture by the excised cotyledons after incubation were greatly diminished by the NH4Cl treatments. Treatment with KCl solutions of the same concentrations as the NH4Cl stimulated the greening, fresh weight increases, and the absorption and incorporation of 14C‐leucine. Desiccation of cotyledons stored at 5°C for 10 days was inhibited by dilute KCl solutions. The toxicity of NH4Cl was alleviated by KCl solutions at low concentrations.
Gibberellins in Diffusates from Shoots of Apple Trees
Authors: GRAUSLUND JØRGEN 
Published: April 2006

AbstractExcised shoot apices, leaves and internodes from shoots of apple trees (Malus×domestica) give off gibberellins by diffusion on agar. A methanol extract of the agar was prepared, the extract separated on thin layer plates, and the gibberellin activity estimated by means of Rumex and lettuce hypocotyl bioassays. The largest amounts of gibberellin are found in diffusates from the shoot apex, the two upper leaves and the two upper internodes. Several promotive fractions are found on the chromatograms as well as growth inhibitors.Removal of young leaves retards elongation of the internodes. Probably gibberellins produced in young leaves exercise some control over this process.The growth regulators Alar and CCC also retard internode elongation. Diffusates from shoots treated with these substances were also examined. Preliminary results suggest that the amount of diffusible gibberellins from treated shoots is not reduced.
The Influence of Urea and Other Nitrogen Sources on Growth Rate of Scots Pine Seedlings
Authors: CHRISTERSSON LARS 
Published: April 2006

AbstractThe growth rate and water content of urea‐fed seedlings of Pinus silvestris L. were compared with those of nitrate‐and ammonium‐fed seedlings grown in continuously renewed nutrient solutions, in which the hydrolysis of urea to ammonia and carbon dioxide was minimized. The growth rate of seedlings grown in an ammonium nutrient solution, in an urea nutrient solution and in a nitrate nutrient solution was about 90 per cent, 75 per cent and 60 per cent, respectively, of that of seedlings grown in a mixture of ammonium and nitrate. Seedlings with urea as the sole nitrogen source developed very severe chlorosis of the needles, the old roots were dark‐coloured, the whole root system was very fragile, and the lateral roots of the third order were missing. Urea‐grown seedlings had the highest nitrogen contents, closely followed by the ammonium and the ammonium + nitrate seedlings. The lowest nitrogen level was in nitrate seedlings. The low growth rate and the chlorosis of urea‐fed seedlings were suggested to be the result of a hydrolysis of urea inside the root, causing an increase in pH and an accumulation of ammonia in the root.