bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Comparison of Phenolic Constituents of Pinus monticola Resistant and Susceptible to Cronartium ribicola
Authors: Hanover J. W. , Hoff R. J. 
Published: April 2006

AbstractPolyphenols and simple phenols in Pinus monticola Dougl. foliage and hark were studied in relation to host resistance to Cronartium ribicola J. C. Fisch. ex Rabenh. More than 50 phenolic substances were detected but no qualitative differences were found between resistant and susceptible trees. Some evidence is given for a quantitative relationship between one polyphenol in white pine foliage and resistance to blister rust. This compound may be a guaiacyl derivative. Differences in phenolics due to tree‐to‐tree variation, needle age, tissue (foliage versus bark), and season of year are also reported.
Artificially Induced Water and Sulfate Transport through Sunflower Roots
Authors: Pettersson Sune 
Published: April 2006

AbstractA new experimental method is used to determine simultaneously the quantity and composition of the sap exuded by a detopped root system at the same time that a pressure deficit of desired magnitude can be applied to the stem stump.The technique was used in a study of the transport of radioactive sulfate through the roots of young sunflower plants placed on complete nutrient solutions labelled with35S.The complications by the time factor on the composition and rate of the sap stream in experiments of this type were observed and discussed. The time of detopping the roots was very critical as the conditions of sulfate transport were greatly changed some time after the excision.A rectilinear connection existed between the rate of sulfate transport in the sap and the water flow at sap flow velocities comparable with transpiration rates. When the transport of water was very slow, the rate of sulfate transport became constant and independent of the water stream. It was suggested that diffusion or water flow could act as motive force for the ion transport in some non‐metabolic phase of transfer in the roots. The addition of 2,4‐DNP to the test solution severely interfered with the water and sulfate transport conditions in the roots.
The Influence of Photosynthetic Factors and Metaholic Inhibitors on the Uptake of Phosphate in P‐Deficient Scenedesmus
Authors: Kylin Anders 
Published: April 2006

AbstractThe cells used in the present investigation had a phosphate content of about 20 per cent as compared with the status in normal cultures. The uptake of phosphate during a period of 4 hours was determined at a pH of 6,5, kept constant with the aid of a citrate buffer.In the absence of CO2, light increased the uptake of phosphate with saturation around 14,000 erg/cm2s. With 5 per cent CO2 in the air the relationship was more complicated, and the uptake of phosphate must he related to more than one process during active photosynthesis.The inhibiting effect of CO2 in air was noticeable already at low concentrations both in light and in darkness. With the system used, this supports earlier indications for internal recycling of orthophosphate, CO2 was inhibiting also in nitrogen in the light.Selenate in a concentration of 2 mM gave a slight and rather irregular inhibition.—Anaerobiosis had no effect in the light but gave a large decrease in the dark.—DNP (0.1 mM) was somewhat more active in the dark than in the light. The lower concentrations tested had no effect in either case.—Menadione (0.1 mM) inhibited strongly, and more in illuminated than in non‐illuminated cells.
The Implication of Auxin in the UV Promoted Expansion of Etiolated Bean Leaf Disks
Authors: Spang Henry A. 
Published: April 2006

AbstractA promotion of expansion of etiolated bean leaf disks by ultraviolet (UV) radiation was confirmed. The optimum conditions for the effeet were found to be 5 seconds UV exposure followed by 24 hours of incubation at 25°C and pH 6.2. Macerations and sections of the treated and control disks indicated that the basis of the response was an increase in the number of cells in the UV treated disks. Experiments with indolebutyric acid (IBA) and p‐chlorophenoxyisobutyric acid (PCIB) indicated that the UV apparently acted to reduce a superoptimal endogenous auxin level to an optimum level which resulted in promotion of the expansion.
An Improvement in the Sensitivity of the Salkowski Reagent for Tryptamine, Tryptophan and Indoleacetic Acid
Authors: Perley James E. , Stowe Bruce B. 
Published: April 2006

AbstractThe reaction of indoles with the Salkowski reagent has been examined. It was found that the concentration of acid as well as the concentration and anionic component of the iron salt employed are critical factors in the choice of a reagent that will fail to react—or will react maximally with a given indole. Tryptamine can be reproducibly assayed with a reagent containing 0.01 M Fe(NO3)3 in 7.0 M HCIO4. Two ml of this reagent are added to two ml of the sample. The absorbancy is read at 450 nm after 90 minutes under uniform light conditions. Versions of this reagent can also be used for the quantitative colorimetric determination of tryptophan or indoleacetic acid.
Effect of Oxygen on the Rate of Photorespiration in Detached Tobacco Leaves
Authors: Tregunna E. B. , Krotkov G. , Nelson C. D. 
Published: April 2006

AbstractThe rate of carbon dioxide exchange in both light and darkness by detached tobacco leaves placed at various oxygen concentrations was measured by an Infra‐Red CO2 Analyzer and a Clark oxygen electrode. It was observed that during illumination oxygen had two different effects. One was to stimulate carbon dioxide evolution and the other to inhibit carbon dioxide absorption.Concentration of carbon dioxide at compensation point was found to be a linear function of oxygen concentration and this has been explained as due mainly to an increased evolution of carbon dioxide. Such an evolution during illumination has been called photorespiration. Increased concentrations of oxygen also had a stimulating effect on the magnitude of the initial post‐illumination burst of carbon dioxide in darkness, but no effect on the subsequent steady rates.These data have been explained as due to the suspension of regular respiration in darkness and its replacement by a different process, tentatively called photorespiration.A second effect of oxygen was to reduce the efficiency (called “carboxylation efficiency”) with which a leaf was able to remove carbon dioxide from the atmosphere.
Transport of Kinetin‐814C in Petioles
Authors: Lagerstedt H. B. , Langston R. G. 
Published: April 2006

AbstractSeveral differences in the translocation pattern of radioactive kinetin in plant petioles were determined. Radioactivity from kinetin‐8‐14C (Kn*) moved from donor agar blocks through petioles of bean and cocklebur but not of cotton. There was no difference in basipetal or acropetal movement of radioactivity from Kn* in cocklebnr petioles, but there was in bean petioles. In bean petioles this movement was preferentially basipetal, but it was influenced by the age of the petiole and by the presence of added indoleactic acid. The combination treatment accelerated the basipetal movement of radioactivity from Kn* in young bean petioles and not in old ones.All data is based on radioactivity translocated into receiver agar blocks which were assayed individually in a liquid scintillation spectrometer. The results show that plant species, direction of transport, age of tissue, and presence of IAA can all influence the translocation of Kn* in petioles.
Stimulation of abscission of Petioles of Phaseolusavulg ris by Sucrose and Gibberellic acid
Authors: Devlin Robert M. , McIntyre Owen M. 
Published: April 2006

AbstractThe influence of Grand sucrose, alone and in combination, on the abscissionarate of petioles of the common be n plant was investigated. application of either Gaorasucrose to the distalatip of one of apair of opposite petiolesa celebrated the abscission of the treated petiole. When the two compounds were applied simult neously less than additive effect was observed. The abscission rate of untreated petioles remain ed practically unchanged by treatment of their opposite partners with G a or sucrose or combinations of these two compounds.
Active Water Transport in Plants
Authors: Oertli J. J. 
Published: April 2006

AbstractThere is no unanimous agreement about a definition of active water transport. The following definition was accepted: During an active transport or process, the water potential must increase and this gain must depend on the decrease in free energy in some metabolic process (5, 10).The passage of water from soil through plants to atmosphere can involve several active steps. A removal of solutes from the water represents a gain of osmotic water potential and this gain can exceed concurrent losses of other water potential components, resulting in a net gain of water potential.An increase of water potential was demonstrated in barley seedlings. Bleeding and guttation liquids were usually found to be more dilute than the external solution. Osmotic and gravitational potential components in exudates, thus, increased while other components remained virtually constant relative to the external solutions. The gain in osmotic potential depends most likely on a metabolic removal of salts: hence, the requirements for an active transport are satisfied. Active water transports, however, are not dependent or connected with the development of root pressure.The existence of active water transports disproves the rule that water flows only along water potential gradients (only against diffusion pressure deficit gradients).A gain in leaf water potential has a physiological significance since the range of soil water potentials a plant can withstand without wilting is extended.
Aflatoxins of Aspergillus flavus Grown on Cassava
Authors: Nartey Frederick 
Published: April 2006

AbstractAspergillus flavus Link ex Fries was grown on cassava (Manihot utilissima) and Czapek‐Dox media at 31±1°C and 90 per cent relative humidity for 8 weeks. Isolation and purification of the toxic and carcinogenic metabolic products of the mould by paper and thin layer chromatography are described. High concentrations of aflatoxin B1, B2, G1 and G2 were synthesized by the mould grown on cassava for 4 weeks. In addition to these four major toxic components, 9 other fluorescent materials were observed on the chromatograms of crude products from cassava.It is concluded that the high moisture, high polysaccharide and low nitrogen content of cassava constitute a favourable nutritional condition at high temperatures and high relative humidity for the growth of A. flavus and the synthesis of relatively high concentrations of aflatoxin. This conld represent a serious health hazard in the moist tropics.
Experimental Studies on the Physiology of the Phycobiont and Mycobiont Ramalina ecklonii By
Authors: Fox Cecil H. 
Published: April 2006

AbstractThe lichenized fungus and alga of the fruticose lichen Ramalini ecklonii were isolated into pure cultures. The ascospores of the fungus failed to germinate in less than five weeks incubation in spite of the use of a variety of cultural conditions. The fungus showed a considerable increase in growth on malt extract agar. Both organisms showed a marked tolerance for high concentrations of glucose although growth was quantitatively reduced. The fungus was able to use a variety of carbon and nitrogen sources as well as an extract of algal cells. Cultivation in the absence of biotin and thiamine failed to yield significant amounts of growth. The alga yielded 27 mg of dry weight after three weeks in a synthetic medium under low light intensities. The alga could be grown in satisfactory amounts on CO2 and inorganic salts with moderate light intensities. Experiments using 14CO2 showed the fungus able to incorporate the extra‐cellular and intra‐cellular products of algal metabolism. The rate of incorporation of extra‐cellular products was inhibited by high concentrations of biotin and thiamine. The alga assimilated l4CO2 which was retained by the cells over a period of 14 days, at which time 78 per cent of the activity was insoluble in 80 per cent ethanol. An extract of the fungus labelled with 14C glucose was partially taken up by the alga and 50 per cent of the label was insoluble in 80 per cent after three days incubation in the light. No lichen acids were found in either the fungal cultures or the algal cultures although large amounts (e.g. 2 liters) of material were extracted and chromatographed. Usnic acid was produced by the intact lichen thallus.
Substrate Dependent Reversibility of Inhibition by β‐Thujaplicin of Glucose and Acetate Respiration in Saccharomyces cerevisiae
Authors: Raa Jan , Goksøyr Jostein 
Published: April 2006

AbstractAttempts to determine the rate of uptake of β‐thujaplicin (TH) and its 1:1 rupric chelate (CuT+) in yeast cells showed in both cases a very rapid equilibration. In the concentration range where respiration is inhibited, most of the TH added was still present in the extracellular fluid, while CuT+ was almost completely removed.The inhibition of glucose respiration by TH was Completely removed when the cells were repeatedly washed, while inhibition of acetate respiration remained. Washing of CuT+ inhibited cells did not release the inhibition of either glucose or acetate respiration.The succinic acid dehydrogenase activity was the same in homogenates of both CuT+ and TH inhibited cells as in homogenates of non‐inhibited cells. Prior to homogenization acetate respiration was inhibited by 60 to 70 per cent by both inhibitors. Alcohol dehydrogenase activity was likewise not affected by TH and CuT+.The formation of acetyl coenzyme A was inhibited by both TH and CuT+ to about the same extent as the respiration of acetate.It is concluded that TH inhibits the acetate respiration by inhibiting the formation of acetyl coenzyme A from acetate. The same site of action is plausible also for CuT+ but in that case, additional sites of inhibition may also be located in the reactions in the Krebs cycle.
The Effect of Light on the Phytolization of Chlorophyllide α and the Spectral Dependence of the Process
Authors: Lilijenberg Conny 
Published: April 2006

AbstractSeven days old dark‐grown etiolated seedlings of wheat cultivated on nutrition solution were given short light impulses of high intensity followed by a dark period, during which the phytolization of chlorophyllic α was studied.If the leaves prior to the short light impulses were given a pretreatment consisting of a light impulse followed by three hours of darkness the phytolization rate increased.Monochromatic light as pretreatment gave a response which was mainly restricted to the red region with a peak around 660 nm.
Partial Synchronization of Cell Division in Suspension Cultures of Haplopappus gracilis
Authors: Eriksson Tage 
Published: April 2006

AbstractFour different chemicals were tested in their ability to synchronize cell division in asynchronous cell cultures of Haplopappus gracilis.Twentyfour‐hour treatments with 5‐amino uracil resulted in a peak in the mitotic index about 14–16 hours after the end of the treatment. The increase in the frequency of mitoses was about three times that of the control.Hydroxyurea, at a concentration of 3 mM, gave after a treatment period of 12–24 hours an increase in the frequency of mitoses which appeared about 10 hours after the treatment. The mitotic index was about 35 per cent, which is 4 times that of the control.5‐Fluorodeoxyuridine (FUdR) at a concentration of 2 × 10−7M gave a mitotic burst about 16 hours after treatment. At that time about 15 per cent of the cells were dividing which was about twice that of the control. The block was reversed with 4 × 10−5M thymidine.Thymidine at a high concentration caused a reduction in the frequency of mitoses during the treatment. After 15 to 16 hours in a thymidine free medium a mitotic peak appeared with a doubling of the frequency of mitoses in treated cells.Cytological studies showed that parlicularly hydroxyurea but also 5‐aminouracil and 5‐fluorodeoxyuridine produced gaps and fragments at the concentrations which gave cell synchronization.
Role of Auxin in Growth of Inhibitor‐treated Oat Coleoptile Tissue
Authors: Ordin L. , Garber M. J. , Skoe B. P. , Rollé G. 
Published: April 2006

AbstractThe role of auxin in the recovery of plant tissue from oxidant treatment was investigated. Treatment of oat coleoptile sections with concentrations of indoleacetic acid (IAA) or 2,4‐dichlorophenoxyacetic acid (2,4‐D) optimal for normal growth, following pretreatment with moderately inhibiting levels of peroxyacetyl nitrate (PAN) immediately accelerated recovery of growth rate. In some cases inhibition was also less at supraoptimal values of auxin. Treatment of ozonepretreated tissue with IAA or 2,4‐D enhanced inhibition at high levels of auxin and produced an optimal growth concentration level which was lower than for sections not given ozone pretreatment. Auxin treatment also reduced the degree of inhibition in fluoride and iodoacetamide‐pretreated sections. Mechanisms by which auxin‐induced recovery from inhibition may occur are discussed.
Acid Phosphatase in Dictyostelium discoideum
Authors: Gezelius Kerstin 
Published: April 2006

AbstractAn acid phosphatase has been studied at various stages of development of Dictyostelium discoideum. This enzyme has a pH optimum of 3.6 and catalyses the hydrolysis of both hexose phosphates and mononucleotides as well as that of p‐nitrophenyl phosphate. The enzyme specific activity increases 2–4 fold in vitro during differentiation, but the activity in vivo may be controlled through endproduct inhibition by orthophosphate, which accumulates in the cells during sorocarp formation. The predicted activity in vivo is highest in the middle of development, especially at the pre‐culmination stage.
Fe and Ca Uptake as Related to Root‐Sap and Stem‐Exudate Citrate in Soybeans
Authors: Brown J. C. 
Published: April 2006

AbstractTwo soybean varieties that differentially absorb and translocate iron were used to compare root‐sap citrate with stem‐exudate citrate as they are involved in the uptake of Fe and Ca. The status of Fe and PO4 in the prenutrient solution determined the citrate concentration in the root sap and the citrate translocated in the stem exudate. There was a parallel between the iron and the citrate translocated in the stem exudate, but this relationship did not appear to exist for the citrate and Fe concentrations in the root sap.Iron stress (deficiency) promoted the accumulation of citrate in the root‐sap, but there was not a concomitant increase of citrate in the stem exudate. In iron‐deficient soybeans, phosphate stress also promoted the accumulation of citrate in the root sap, and here, stem‐exudate citrate and root‐sap citrate more nearly followed the same trends. The citrate pool in the root appears to result from a deficiency of iron and may not be directly involved in the absorption and translocation of iron from the growth medium. Increasing amounts of phosphate in the prenutrient decreased both the citrate and Fe in the root sap and stem exudate.The factors controlling the uptake of Fe are rather specific and are not related to the uptake of radioactive Ca 45 in soybeans regardless of soybean variety, degree of iron stress, or citrate concentration in the root.
Protein Synthesis as a Requirement for Wound Xylem Differentiation
Authors: Fosket D. E. , Miksche J. P. 
Published: April 2006

AbstractAn increasing rate of protein synthesis was observed during the first 2 days after the isolation of 2 mm thick internodal stem slices of Coleus on a sucrose‐agar medium. This rise in the rate of protein synthesis preceeded the first visible signs of wound‐vessel member differentiation in the cultured stem slices. Irradiation of tissue slices with 4000 R of x‐rays at isolation reduced the numbers of wound‐vessel members differentiated after 7 days in culture by 51 per cent, and this level of x‐irradiation was observed to inhibit protein synthesis by the cultured stem slices. Treatment of the tissue slices with exogenous auxin (0.05 mg/1) after irradiation did not alter the degree of inhibition of xylem differentiation. Actinomycin D inhibited wound‐vessel member differentiation, but it had no effect on the endogenous growth of the cultured stem slices. Similarly, auxin at 0.05 mg/1 was without effect on the endogenous growth rate of the stem slices. Actinomycin D treatment was highly effective in inhibiting xylem differentiation if it was supplied to the tissues within the first 48 hours after isolation; actinomycin D treatment had no significant effect on xylem differentiation when it was given after the first 2 days of culture. Chloramphenicol (10−3M) inhibited both xylem differentiation and the endogenous growth of the cultured stem slices.
Action de la kinétine sur la croissance et la teneur en chlorophylles des racines
Authors: Pilet P. E. , Hofer R. M. 
Published: April 2006

Abstract Lens roots form chlorophylls in well‐developed chloroplasts when they are cultivated in continuous light.Chlorophyll accumulation was increased when kinetin (10−4M) was added for a short time (24 h) of treatment. For a long time (72 h), the increase of chlorophyll content was reduced when roots were cultivated in light and with kinetin.When the roots were transferred from light to dark, chlorophyll content was decreased. This reduction was inhibited when roots were treated with kintin.From these present result it was supposed that kinetin acts on the catabolism and the anabolism of chlorophyll. The necessity of kinetin for chloroplast from amyloplast maturation and differentiation was discussed.
Requirement of RNA for the Auxin‐induced Elongation of Oat Coleoptile
Authors: Masuda Yoshio , Wada Shunji 
Published: April 2006

AbstractUsing etiolated oat coleoptile segments the following results were obtained.Actinomycin D pretreatment for one hour produced about 50 per cent inhibition of RNA synthesis (labeled uracil incorporation), but the elongation caused by IAA was not inhibited in the following 5 hours at least. Actinomycin D pretreatment for three hours produced about 75 per cent inhibition of RNA synthesis and almost complete inhibition of subsequent IAA‐induced elongation, which is accompanied by the inhibition of IAA‐induced increase in cell wall extensibility. The inhibiting effect of actinomycin D seemed to be reduced when IAA was given within a certain period.
Regeneration after Wilting, Growth and Yield of Wheat Plants, as Affected by Two Growth–Retarding Compounds
Authors: Plaut Z. , Halevy A. H. 
Published: April 2006

AbstractThe effect of spraying with 2–chloroethyltrimethylammonium chloride (CCC) and N‐dimethylaminosuccinamic acid (B‐995) on wheat plants exposed to various durations of wilting, was studied. The chemicals had little or no effect on dry matter production, grain yield, or water requirement of plants watered regularly or exposed to a short drought period causing one day of wilting. In plants exposed to two drought cycles of 5–6 wilting days each, a very pronounced increase in dry weight and grain production was found in plants treated with the two growth retardants. This effect was due to the increased ability of the treated plants to regenerate new shoots on rewatering after wilting. Longer drought periods of 10–12 wilting days, caused complete desiccation of both treated and untreated plants. The mode of action of the chemicals in increasing the drought tolerance of plants is discussed in relation to their effect on delaying the senescence of detached leaves.