bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of phenolic substances on metabolism of exogenous indole‐3‐acetic acid in maize stems
Authors: LEE T. T. 
Published: April 2006

AbstractFour‐day‐old stem segments of Zea mays L. cv. Seneca 60 were treated sequentially with phenolic substances and indole‐3‐acetic [2‐14C] acid ([2‐14C]IAA). Formation of bound IAA was rapid, but a pretreatment with p‐coumaric acid, ferulic acid or 4‐methylumbelliferone decreased the level of bound IAA. The decrease is not likely related to the effect of the phenolics on enzymic oxidation of IAA, since the level of free IAA was not limiting and the activity of ferulic acid in enzymic oxidation of IAA is different from that of p‐coumaric acid and 4‐methylum‐belliferone. Apparently these compounds inhibited the formation of bound IAA and consequently caused an accumulation of free IAA. In contrast, caffeic acid, protocatechuic acid and 2,3‐dihydro‐2, 2‐dimethyl‐7‐benzofuranol had little effect.After the uptake of IAA there was a slow but steady incorporation of the radioactivity into the 80% ethanol‐insoluble, 1 M NaOH‐soluble fraction. Phenolic substances also affected this process. The compounds which are cofactors of IAA‐oxidase increased the incorporation while those which are inhibitors of IAA‐oxidase decreased the incorporation. Results suggest that the phenolics also affected the enzymic oxidation of IAA in vivo in the same way as in vitro.
Turnover of cell wall polysaccharides of a Vinca rosea suspension culture
Authors: TAKEUCHI YUICHI , KOMAMINE ATSUSHI 
Published: April 2006

AbstractFive‐day‐cultured cells of Vinca rosea suspension culture were labelled with D‐[U‐14C]glucose for 3 h and were then incubated in a medium containing unlabelled glucose for 24 h. Before and after chasing, extra‐cellular polysaccharides (ECP) and the cell walls were isolated from the medium and cells, respectively. ECP and polysaccharides in the hemicellulose fraction of cell walls were fractionated into a fraction precipitated as copper salt and one not precipitated as copper salt, and the latter was further fractionated using cellulose‐powder chromatography. From the results of analyses of the sugar composition and methylation analyses, components of polysaccharides contained in each fraction were deduced. In ECP, the percentage of radioactivity in the arabinogalactan fraction increased during chasing, while in the cell wall radioactivity in the fraction containing arabinogalactan decreased during chasing. These results confirm the view that arabinogalactan in the cell wall is degraded, and secreted into the medium as a part of ECP.
Plantlet formation from embryonic tissue of chestnut grown in vitro
Authors: VIEITEZ ANA M. , VIEITEZ E. 
Published: April 2006

AbstractDevelopment of axillary shoots was induced when isolated embryonic axes of chestnut (Castanea sativa Mill.) were cultured on a defined medium containing 6‐benzyl‐aminopurine (BAP). The optimal concentrations of BAP were determined for development of axillary shoots from both embryonic axes and subcultured shoots. After shoot multiplication a great number of shoots have been maintained sequentially without significant change in the proliferative rate for one year. Limited rooting has been obtained with excised shoots. Indole‐3‐butyric acid (IBA) at 2 mg/l was used to induce root primordia. After 8 days of treatment the plantlets were transferred to an auxin‐free medium for root development.
Importance of the caryopsis in root growth and georeaction
Authors: NEY DANIEL , PILET PAUL‐EMILE 
Published: April 2006

AbstractGeocurvature of horizontally placed apical segments of maize (cv. INRA 258), the lateral curvature of half‐decapitated segments in vertical position, and the curvatures of intact primary roots (horizontal or vertical) still attached to their caryopses were analysed in white light. The results may be explained in terms of the growth properties of certain endogenous regulators. The caryopsis could be the source of some precursors of growth inhibiting substances produced or released in the cap cells and also of growth activators. The relative effects of these factors – acting in the elongating zone of growing roots – clearly depend on the orientation of the caryopsis.
Effects of ionic strength and relative humidity on the efflux of K+ (86Rb) and Ca2+ (45Ca) from roots of intact seedlings of cucumber, oat and wheat
Authors: JENSÉN PAUL , KYLIN ANDERS 
Published: April 2006

AbstractSpring wheat (Triticum aestivum L. cv. Svenno), oat (Avena sativa L. cv. Brighton) and glasshouse cucumber (Cucumis sativus L. cv. Bestseller F1) were cultured for a week after germination on complete nutrient solutions of three different dilutions (1, 25 and 50% of the full strength medium). K+(86Rb) and 45Ca were present during the whole culture period. Relative humidity (RH) was 50% except during the last day, when half the material was transferred to 90% RH. Efflux of labelled ions was then followed during eight hours on unlabelled solutions of the same composition as before, and at both 50% and 90% RH in the atmosphere. – Uptake of K+(86Rb) during growth tended to be saturated in the 25% medium. Contrariwise, the level of Ca2+ in the roots increased continuously with strength of the medium. At low concentrations cucumber roots were higher in Ca2+ than roots of oat or wheat, whereas all three species showed similar levels of Ca2+ in 50% medium. – At the lowest ionic strength, smooth efflux curves were obtained that could be resolved according to the three‐compartment theory. At higher ionic strength, irregularities were observed, and more for Ca2+ than for K+; but for practical purposes compartment analysis with the same time constants could be applied as for the lowest concentration. – Discrimination between K+ and Rb+ differed between the roots, but not much between the shoots of different species. The roots of oat and wheat took up Rb+ preferentially over K+ in the 25% and 50% media; whereas K+ was preferred over Rb+ or little discrimination made in 1% medium and for cucumber. The shoots generally showed less discrimination than the roots. The main variability in discrimination between K+ and Rb+ thus appears to be localized in the tonoplasts of the roots cells. – Low RH around the shoots increased efflux of K+(86Rb) from the cytoplasm and vacuoles of the root cells as compared to the efflux at high RH. DNP (2,4‐dinitrophenol) in the medium had the same effect as high RH around the shoots. The signal system that must exist between shoots and roots is discussed as a response to “drought” conditions. In relation to investigations of others, it is assumed that the effect of DNP may indicate that part of the chain between roots and shoots consists of metabolically influenced sites, whose output is influenced by the rate of water transport.
Comparative study of RNA metabolism in freshly isolated protoplasts and callus cultures of Parthenocissus tricuspidata crown gall
Authors: ZUILY‐FODIL Y. , ESNAULT R. 
Published: April 2006

AbstractRNA metabolism was compared in protoplasts and cells of Parthenocissus tricuspidata crown gall callus. A rapid increase in the permeability to precursors during the first three hours following the termination of protoplast isolation was observed. Consequently, RNA synthesis occurred at a higher rate in protoplasts than in whole cells. On the other hand, protoplasts and callus tissues showed similar kinetics of incorporation of precursors into mature rRNA's. Pulse‐chase experiments showed the maturation rate to be nearly the same in both cases.
Succinate oxidation by coupled potato tuber mitochondria followed by rapid scan spectrometry
Authors: DUCET GASTON 
Published: April 2006

AbstractOxidation of succinate by potato tuber mitochondria has been investigated from aerobiosis to complete anuerobiosis. Difference spectra of the various steps were recorded by a rapid scan spectrometer delivering averaged spectra every 3 s in the range 380 to 630 mm.The transitions between state 3 and 4 resulted in large redox changes, essentially for the b cytochromes, and in significant changes in the spectral baseline (light scattering). At anaerobiosis the cytochromes c, c1 and a were reduced while cytochrome a, remained oxidized. – Addition of uncouplers in aerobiosis induced oxidation of the b cytochromes, and when anaerobiosis occurred cytochromes c, c1a and a3 were reduced simultaneously. When uncouplers were added in anaerobiosis a partial oxidation of the b cytochromes and the reduction of cytochrome a3 were observed.These results are interpreted as the building up of a membrane potential, maximal in state 4 and stable after anaerobiosis. The cytochromes buried in the membrane equilibrate with the membrane potential, and their redox states are sensitive to the changes. Variations of membrane potential also induce changes in the light scattering by the mitochondrial membrane.
The influence of zinc and light conditions on the cadmium‐repressed growth of the green alga Coelastrum proboscideum
Authors: MÜLLER KLAUS W. , PAYER HANS‐D. 
Published: April 2006

AbstractThe growth response of Coelastrum proboscideum Bohlin to cadmiun (3 × 10−9M to 2.4 × 10−7M) was studied. The inorganic media used varied in zinc concentration (1.3 × 10−7M to 3.6 × 10−6M). The data were evaluated by factorial analyses. The influence of zine on the growth depression by cadmium depended on the light conditions (16:8 h light:dark cycles or 24 h continuous illumination periods). Intermittent illumination caused a negative interaction of zinc and cadmium in contrast to a positive interaction or additive effects of these elements during continuous illumination.
Growth and curvature in seedlings of Pisum sativum and an ageotropic mutant
Authors: OLSEN GUNN MARI , IVERSEN TOR‐HENNING 
Published: April 2006

AbstractIn an attempt to explain the influence of gravity on the behaviour of ageotropic plant organs, a pea mutant (Pisum sativum ageotropum) and normal pea (Pisum sativum cv. Sabel) were examined. The mutant has a significantly lower germination rate (large seeds: 25%, small seeds: 10%) than normal pea seeds (55%). Removal of testa increased germination dramatically, the values obtained were 63 and 89%, respectively. Immediately after imbibition the mutant from which the testa had been removed, developed more slowly than normal pea seeds; after 28 h the difference in elongation rate between the two types was reversed. When continuously stimulated geotropically in the horizontal position the elongation in the mutant is larger than in the normal pea roots kept in the same position. During a 24 h period starting 48 h after imbibition the mutant root elongated 45.0 mm while the value for the normal pea root was 11.5 mm.The course of the geotropic curvature in roots of the two types has been followed during a period of 24 h. Normal pea roots develop an asymmetry in the extreme root tip region after 30 min of horizontal stimulation. After prolonged stimulation (exceeding 2 h) the asymmetry has disappeared and the curvature distributed over the entire growth region. When roots of normal pea are stimulated continuously at various angles, the optimum angle of geotropic response is 90° with decreasing responses in the order 135° (i.e. the root tip is pointing obliquely upward) and 45°. The presumed ageotropic behaviour of the mutant has only to a certain extent been confirmed in the present study. When stimulated at 135° a slight positive curvature developed; stimulation at 90° and 45° gave a slight negative curvature.
Qualitative and quantitative changes in nitrogenous compounds in senescing leaf and bark tissues of the apple
Authors: KANG SEONG‐MO , TITUS JOHN S. 
Published: April 2006

AbstractQuantitative and qualitative changes in proteins and ethanol‐soluble nitrogen were followed in senescing leaf and bark tissues of ‘Golden Delicious’ apple trees (Malus domestica Borkh.). While senescing leaves lost 46% of their proteins, total bark protein increased 240% during senescence. However, the protein nitrogen gain in bark tissue was about the same as the protein nitrogen loss in leaf tissue per unit fresh weight of tissues. The pattern of bark protein accumulation appears to be gradual from early August to November and sequential from lower to higher molecular weight species of proteins. The final electrophoretic profile of total bark proteins was established at the later stages of senescence. By late November, 89% of the nitrogen in the bark tissue was found in proteins with 11% in the ethanol‐soluble fractions. The total protein content of dormant bark tissue was 3.5% per gram dry tissue. Fractionation of the total bark proteins by DEAE‐cellulose chromatography indicated that the final upsurge of bark proteins observed in November was associated primarily with one group of proteins (Peak III).
Activity profiles of enzymes involved in glutamine and glutamate metabolism in the apple during autumnal senescence
Authors: KANG SEONG‐MO , TITUS JOHN S. 
Published: April 2006

AbstractSeasonal changes in glutamine synthetase (EC 6.3.1.2), glutamate synthase (EC 2.6.1.53), and glutamate dehydrogenase (EC 1.4.1.3) were measured in both senescing leaf and bark tissues of ‘Golden Delicious’ apple trees (Malus domestica Borkh.). From the measured enzyme activities we attempted to estimate the in vivo catalytic potentials of the enzymes with special reference to nitrogen mobilization and conservation of senescing apple trees. The cumulative glutamine synthetase activity of leaf tissue was about three times higher than that of bark. The estimated catalytic potential of leaf glutamine synthetase was 800‐fold higher than the actual protein nitrogen loss of senescing leaves. The cumulative glutamate synthase activity of bark was about six times higher than that of leaf. The estimated catalytic potential of bark glutamate synthase was 160‐times higher than the actual protein nitrogen gain in that tissue. The cumulative glutamate dehydrogenase activities in leaf and bark tissue were approximately the same. However, the catalytic potential of leaf glutamate dehydrogenase was twice that of leaf glutamate synthase. It is thus concluded that the physiological role of glutamine synthetase in senescing leaf tissue is to furnish the amide(s) prior to mobilization of nitrogen to storage tissue. The higher activity of glutamate synthase in bark tissue could provide a mechanism to transform the imported amide nitrogen to amino nitrogen of glutamate for storage protein synthesis. The possible regulatory factors upon the activity of these enzymes in the tissues of senescing apple trees are discussed.
Nitrogen assimilation by a Citrus tree
Authors: KATO TADASHI 
Published: April 2006

AbstractPrimary assimilation of 15N‐ammonium or 15N‐nitrate by excised leaves of satsuma mandarin (Citrus unshiu Markovitch) was examined under light and dark conditions. Under both conditions both types of nitrogen were most markedly incorporated into glutamine‐amide nitrogen in the primary step of the assimilation, and into proline in the later steps. Incorporation of ammonium or nitrate into amino acids was more active in the light than in the dark, although the stimulating effect of light on the incorporation was relatively small in both cases.
Effect of ortho‐dihydroxyphenols on growth and protein pattern of callus cultures from Prunus avium
Authors: FEUCHT W. , SCHMID P. P. S. 
Published: April 2006

AbstractExcised shoot discs from Prunus avium L. were cultivated on a modified Murashige and Skoog medium for 4 weeks under long day conditions. The basal medium was supplemented with IAA and benzylaminopurine. Further addition of 5.7 × 10−5 resp, 11.4 × 10−5M catechin and 4.25 × 10−5 resp. 8.5 × 10−5M chlorogenic acid resulted in a highly significant promotion of callus proliferation. Proteins and enzymes were separated by isoelectric focusing. The supply of both polyphenols resulted in a higher number and intensity of protein bands including esterases as compared to controls.
Growth control by phytochrome of de‐etiolated bean hypocotyls mediated by chlorophyll fluorescence
Authors: ROTH‐BEJERANO N. 
Published: April 2006

AbstractThe elongation of hypocotyls excised from de‐etiolated seedlings of beans (Phaseolus vulgaris L. cv. British Wax) is inhibited by light, blue and red irradiations being equally effective. Conditions which decrease chlorophyll fluorescence, such as CO2‐free air, abolish the inhibitory effect of blue irradiation and enhance the inhibition by red light. Conversely, conditions which increase chlorophyll fluorescence, such as a N2 atmosphere or irradiation through a chlorophyll filter, abolish the inhibitory effect of red light and enhance the inhibition by blue irradiation. The inhibitory effect of blue light is reversible by red irradiation under increased fluorescence as well as by far red. We propose that the chlorophyll fluorescence excited by blue and red irradiations in λF > 660 nm and λF > 720 nm, respectively, is responsible for the inhibitory effect of blue light and the reduction of the inhibitory effect of non fluorescing red light. Both red and blue wavelengths seem, therefore, to control hypocotyl elongation through phytochrome.
Membrane lipids in heat injury of spinach chloroplasts
Authors: SANTARIUS KURT A. 
Published: April 2006

AbstractHeat treatment of intact leaves and of isolated thylakoid membranes from spinach (Spinacia oleracea L. cvs. Monatol and Montako) caused inactivation of photochemical processes such as electron transport through photosystem II and photophos‐phorylation. Membrane lipid analysis demonstrated that heat‐induced damage to thylakoids is not caused by chemical alterations in the lipids such as oxidation of unsaturated fatty acids, or release of free fatty acids due to hydrolysis of lipids. Partial extraction of lipids from isolated chloroplast membranes before and after thermal inactivation do not point to drastic changes in the binding relations of the lipids within the membranes. However, it cannot be excluded that during high temperature treatment changes in lipid‐lipid interactions and/or delocalization of specific lipids within the thylakoids might be responsible for the disorganization of the functional integrity of the membranes. Since thermostability of chloroplast membranes is decreased when they are exposed to free unsaturated fatty acids, small amounts of membrane lipids which become hydrolyzed during extended heat treatment may partly contribute to primary heat damage.
Hormonal factors controlling the initiation and development of lateral roots
Authors: WIGHTMAN FRANK , THIMANN KENNETH V. 
Published: April 2006

AbstractAs the first part of a comprehensive study of the hormonal control of lateral root initiation and development, the effect of surgical treatments such as removal of the root tip, one or more cotyledons, the young epicotyl, or combination of these treatments, on the induction and emergence of lateral roots on the primary root of pea seedlings has been examined. Results show that removal of the root tip leads to a rapid but transitory increase in the number of lateral primordia, the largest number arising in the most apical segment of decapitated roots suggesting the accumulation of acropetally moving promoter substances in this region. The cotyledons appear to be the main source of promoter substances for both the induction and emergence of lateral roots, although one or more promoters also appear to be produced in the epicotyl. The data further indicate that the root tip is possibly the source of a substance which moves basipetally and interacts with acropetally moving promoters to regulate the zone for lateral primordia initiation; the root tip also appears to be the source of a powerful inhibitor of lateral root emergence.
Embryonic control of isocitrate lyase activity in the megagametophyte of ponderosa pine seeds
Authors: MURRAY EDWARD W. , ADAMS ROBERT E. 
Published: April 2006

AbstractA previous report (Bilderback 1974) presented evidence for embryo enhancement of isocitrate lyase (threo‐L, isocitrate glyoxylate lyase, EC 4.1.3.1) activity in the megagametophytes of stratified germinating Pinus ponderosa Laws. var. ponderosa seeds. Our data indicate that the rate of increase in specific activity of this enzyme was greater during the first four days under germination conditions in ponderosa pine megagametophytes from which embryos had been excised than in megagametophytes with embryos left in situ for a 12‐day incubation period. Enzyme activity also increased more rapidly in megagametophytes with embryos removed after 2 days incubation than in those that retained their embryos for the full incubation period. Although rate of increase in enzyme activity was greater in embryoless megagametophytes than in those retaining their embryos, highest levels of activity ultimately occurred in the latter. Thus embryo presence was associated with inhibition of the rate of development of enzyme activity but it was also responsible for a pattern of sustained enzyme activity. These phenomena were not dependent on stratification. Possible reasons for differences between certain aspects of our study and the above cited report are discussed.
Tentoxin effects on infrastructure and greening of ivyleaf morningglory (Ipomoea hederacea var. hederacea) cotyledons
Authors: DUKE STEPHEN O. , PAUL REX N. , WICKLIFF JAMES L. 
Published: April 2006

AbstractThe effects of 20 μM tentoxin on mesophyll chloroplast ultra‐structural development, chlorophyll organization and accumulation, and pigment transformations in cotyledons of dark‐grown, 4‐day‐old ivyleaf morningglory [Ipomoea hederacea (L.) Jacq. var. hederacea]were monitored. After 6 h of white light (200 μEm−2T.s−1), many plastids of tentoxin‐treated tissues contained prolamellar bodies or inconsistent internal membrane orientation in contrast to the uniform internal membrane orientation and absence of prolamellar bodies in controls. Grana stacking did not progress beyond three to four disc loculi in tentoxin‐treatments, and fret membranes were usually discontinuous and reduced. Cylindrical or cupped grana appeared in many chloroplasts after 3 days of light, while other chloroplasts in which disruption was more pronounced had few grana except for remnants, but usually did possess vesicles or structures resembling prolamellar bodies. Tentoxin had no apparent effect on stroma density or plastoglobuli size and number. No starch grains appeared in any of the tentoxin treatments, whereas they appeared after 24 h in controls. Initial protochlorophyllide content and its photoconversion to chlorophyllide and subsequent Shibata shift were not affected by tentoxin. Chlorophyll accumulation rates in tentoxin‐treated cotyledons were about 10% of control rates during the first 24 h of greening and about 20% of controls from 48 to 72 h of greening. Chlorophyll alb ratio and PSU size (total Chl/P700) were not significantly affected by tentoxin.
Recovery of loss in chlorophyll and 2,6‐dichlorophenol indophenol Hill reaction of isolated chloroplasts during dark induced aging of intact maize seedlings
Authors: CHOUDHURY N. K. , BISWAL U. C. 
Published: April 2006

AbstractLoss in the content of pigments and decline in the efficiency of thylakoid membranes to reduce 2,6‐dichlorophenol indophenol (DCPIP) have been investigated during dark induced senescence of attached leaves of maize seedlings. The chlorophyll degradation during senescence is differentially inhibited by indoleacetic acid (IAA), gibberellic acid (GA) and kinetin. IAA and GA behave as mild senescence inhibitors in comparison to kinetin. However, in comparison to light, kinetin is relatively less efficient in counteracting senescence. Dark‐induced loss in chlorophyll content is fully recovered by light when the dark incubation period is relatively short. The pattern of light recovery of loss in photoelectron transport during dark‐aging is similar to the recovery kinetics of chlorophyll. Continuous kinetin treatment of dark‐incubated seedlings inhibits the chlorophyll degradation but with decreased duration of kinetin treatment, the efficiency of the hormone to inhibit chlorophyll loss is reduced. The kinetin‐induced inhibition of pigment loss is small in comparison with the effect of light.