bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Effect of Monochromatic Light on α‐Linolenic and Trans‐3‐Hexadecenoic Acids Biosynthesis, and Its Correlation to the Development of the Plastid Lamellar System
Authors: TRÉMOLIÉRES A. , GUILLOT‐SALOMON T. , DUBACQ J.‐P. , JACQUES R. , MAZLIAK P. , SIGNOL M. 
Published: April 2006

AbstractSeven day old etiolated Zea mays L. (cv. Wisconsin 355) seedlings were illuminated for 20 h under monochromatic radiations (100 Á pass band) produced by a spectral illuminator of high energy. Four regions of the visible spectrum were observed to stimulate chlorophyll synthesis. With poorly developed leaves (grown for 7 days at 22°C: experiment A). the most efficient wavelengths were found to be in the blue and green (between 445 and 505 nm). yellow (between 580 and 605 nm) and red (maximum 650 nm) parts of the spectrum. With well developed leaves (grown for 7 clays al 27°C: experiment B), a slight displacement of the maxima towards shorter wavelengths was observed. 14C‐acetate was furnished to illuminated maize seedlings to follow lipid synthesis during greening. In the leaves of experiment A, the biosynthesis of α‐linolenic acid and monogalactosyldiacylglycerol followed chlorophyll accumulation. In the more developed leaves of experiment B. containing higher amounts of galactolipids, the biosynthesis of α‐linolenic acid and monogalactosyldiacylglycerol followed chlorophyll accumulation only in blue and yellow light. The biosynthesis of trans‐3‐hexadecenoic acid was strictly dependent on the wavelength of the irradiating light in the leaves of experiment A; it was optimal under blue (420 nm) and still very high under yellow (580 nm) and red (650 nm). In the more developed leaves of experiment B, it was optima in blue (445 nm) and in yellow (580 nm), and the red maximum was shifted to 630 nm. All C‐trans‐3‐hexadecenoic acid was incorporated into phosphatidylglycerol.A marked relationship was observed between the intensity of galactolipid synthesis and the development of the lamellar system of maize plastids during greening. A positive correlation could be established between the biosynthesis of trans‐3‐hcxadeccnoie acid and the development of well constituted grana stacks in the plastids.
Chemical Forms of Nickel and Cobalt in Phloem of Ricinus communis
Authors: WIERSMA DOUWE , VAN GOOR BEREND J. 
Published: April 2006

AbstractInvestigations were performed to study the chemical form in which nickel and cobalt are transported in sieve tubes. Ricinus communis plants were used since they allow easy collection of relatively pure phloem sap. In the experiments labelled nickel or cobalt were given to the nutrient solution. The tapped phloem exudate was separated by gel filtration on Sephadex or by paper electrophoresis. Nickel and cobalt were bound to complexing organic compounds with a molecular weight in the range of 1000—5000. The overall charge of the nickel complex was negative, and the bulk of cobalt also appeared to complex to a compound with negative overall charge.
The Accumulation and Transport of Calcium in Barley Roots
Authors: SINGH CHANCHAL , JACOBSON LOUIS 
Published: April 2006

AbstractThe accumulation and transport of Ca by various zones of 6‐day old barley roots (Hordeum vulgare L.) were examined with special reference to their relationship to the salt status of the root. The initial salt content had a profound effect on Ca transport and a lesser effect on Ca accumulation. High‐salt roots transported Ca in much larger amounts than did low salt roots. In low salt roots the apical zone was more active in transporting Ca to the conducting tissue than were the mid or basal zones However, in high salt roots all zones were about equally active in transporting Ca. The metabolic inhibitor, DNP, had little effect on accumulation but inhibited transport very effectively. The effect of DNP was more pronounced on transport from the apical zone than from the other root zones. Calcium applied anywhere along the root length moved only basally and its polarized longitudinal movement was maintained irrespective of the salt status of the root. The movement of Ca was characterized by a rapid release of preabsorbed Ca and a ready exchange of apoplastic Ca. The hypothesis is presented that cellular Ca is in a relatively mobile state. Its entry into the symplasm is the rate limiting step in longitudinal transport and its overall movement is metabolically controlled.
Hormonally Induced Polyembryos in Wheat
Authors: FERGUSON J. D. , McEWAN J. M. , CARD K. A. 
Published: April 2006

AbstractIt had been shown previously that wheat plants, which had been sprayed with auxin herbicide al flowering lime, produced seeds with extra shoots. These shoots have now been found lo belong So new, and relatively normal, embryos formed in the lower part of the scutellum.
Relationship between Position on the Parent Plant and Dormancy Characteristics of Seeds of Three Cultivars of Celery (Apium graveolens)
Authors: THOMAS T. H. , BIDDINGTON N. L. , O'TOOLE DIANE F. 
Published: April 2006

AbstractGermination and seedling emergence studies were made on seeds harvested from four different umbel positions of three cultivars of celery (Apium graveolens L.). Although heavier seeds were produced from primary umbels than from other umbels, these were less viable as measured by the germination percentage at I8°C in the light. However, germination of viable seeds from quaternary umbels was lower than that of seeds from primary umbels at 18°C in the dark when incubated with GA4, (2 × 10 −4M) and seed from secondary and tertiary umbels tended to be intermediate in response. All viable seeds germinated when N6‐benzyladenine (10−2M) was used in combination with GA4. Seeds from quaternary umbels of two of the cultivars had a lower high‐temperature limit for germination in the dark than did seeds from other umbels. In glasshouse experiments the emergence of viable ‘quaternary’ seeds of these cultivars was higher than that of ‘primary’ seeds. Under these conditions the time to 50% of the final emergence as determined after 42 days was similar for seeds from all umbel positions within each cultivar. In two varieties seedling weights were greater from seeds of primary as compared to quaternary umbels, and in general, the largest seedlings arose from the heaviest seeds and the smallest from the lightest seeds in all three cultivars.
Putrescine and Spermidine in Peas: Effeets on Nitrogen Source and Potassium Supply
Authors: KLEIN H. , PRIEBE A. , JÄGER H.‐J. 
Published: April 2006

AbstractFree and total putrescine and, to a lesser extent, spemidine accumulate in both roots and shoots of peas in response to potas stum deficiency and ammomnium supply. Free putrescine responds more sensitively than total putreseine to variatioin of nutrients. Accumulation of putrescine is more pronounced in the roots than in the shoots.
Metabolic Study of Douglas‐fir Pollen Germination in vitro
Authors: MUREN ROGER C. , CHING T. M. , CHING KIM K. 
Published: April 2006

AbstractDouglas‐fir [Pseudotsuga menziesii (Mirb.) Franco] pollen was germinated and grown in mass in a sterile mineral medium supplemented with 0.3 M mannitol as osmotic stabilizer. During the 4‐day period, pollen elongated threefold; free sugar and amino acid contents did not change significantly; soluble protein, insoluble protein, and RNA decreased; starch reduced to 30%; and DNA doubled in quantity. Respiration rate remained high and constant during the first 36 h and then increased, but the respiratory quotient averaged about 1.0 throughout the period. The pool size of adenine nucleotides remained constant, whereas ATP content and energy charge increased rapidly during the first 8 h and remained high for the remainder of the period. 14C‐glucose was rapidly metabolized within 2 h at 25°C to amino acids (33%), organic acids (22%), sugars (20%), CO2 (15%), lipids (5%), and insoluble components (3%). Experimental data indicated that the cultural conditions provided a suitable environment for rapid germination and active metabolism of Douglas‐fir pollen.
Effects of Glyphosate on Metabolism of Phenolic Compounds
Authors: DUKE STEPHEN O. , HOAGLAND ROBERT E. , ELMORE C. DENNIS 
Published: April 2006

AbstractLight enhanced the inhibiting effect of root‐fed glyphosate (5 × 10−4M) on dry weight accumulation of soybean [Glycine max. (L.) Merr.] seedling axes. Inhibition of growth by light was greatest in hypocotyls, whereas by glyphosate it was greatest in roots. A synergistic effect of light and glyphosate on stimulation of phenylalanine ammonia‐Iyase (PAL, E.C. 4.3.1.5) activity was also demonstrated. In continuous white light PAL activity increased linearly for 4 days in axes of seedlings exposed to glyphosate. Evidence of phytochrome involvement in the light effect was shown. The stimulatory effect of glyphosate on PAL activity was greater in roots than in hypocotyls. Soluble hydroxyphenolic compound levels were reduced by glyphosate but were increased by light on a per axis basis. On a fresh weight basis, hydroxyphenolics were more concentrated in glyphosate‐treated than in control tissues in the light. When compared to other amino acids, disproportionate decreases in free pools of phenylalanine and tyrosine occurred in axes of seedlings treated with glyphosate and light. The effect of light on all measured parameters was mainly in the hypocotyl, while that of glyphosate was primarily in the root. In the light, glyphosate caused increases in levels of glutamine and other amino acids that may be the result of amination reactions, protecting from excess ammonia generated by enhanced PAL activity. These results suggest that PAL has a strong influence on its substrate levels in this system and/or that glyphosate inhibits synthesis of aromatic amino acids.
Nitrate and Nitrite Reduction in Wheat Leaves as Affected by Different Types of Water Stress
Authors: HEUER BRURIA , PLAUT Z. , FEDERMAN EVELYN 
Published: April 2006

AbstractThe effect of different types of water stress on nitrate and nitrite reductases of wheat (Triticum vulgare L. cv. Mivhor) leaves was investigated. Water stress was applied either to leaf tissue by its incubation in mannitol or various salt solutions, or to intact plants by exposure of the root system to low temperatures or to salinity. Nitrite reductase was much less sensitive to water stress than nitrate reductase, and was not sensitive to salinity up to osmotic potentials of about — 13 bars.The decrease in nitrite reductase activity by water stress was attributed to a direct inhibition of the enzyme rather than to a repression of enzyme synthesis. This was based on the fast response of the enzyme after exposure of leaf tissue to reduced osmotic potential, on the lack of a continuous decrease in enzyme activity during a prolonged stress, and on the fact that light activation of reductase was unaffected by water stress.The inhibition of nitrate reductase under water stress was attributed to both a direct inhibition and a reduced rate in enzyme synthesis. This is concluded from the fact that a decrease in its activity was obtained already within 1 h after stress application and from the fact that light induction of the enzyme was inhibited by stress.
Properties of Plasmamembrane ATPase and Mitochondrial ATPase of Saccharomyces cerevisiae
Authors: PETERS P. H. J. , BORST‐PAUWELS G. W. F. H. 
Published: April 2006

AbstractThe properties of mitochondrial ATPase and plasmamembrane ATPase of Saccharomyces cerevisiae are compared. The pH dependence differs considerably. At low pH plasmamembrane ATPase is inactivated. High salt concentrations protect the ATPase against acid inactivation. K+ is more effective than Na+. The sensitivity of mitochondrial ATPase towards azide, Dio 9 and oligomycin is far greater than found with plasmamembrane ATPase. There are no indications that the membrane ATPase is involved directly either in monovalent cation uptake or in divalent cation uptake. Sr2+ and Ca2+ do not activate plasmamembrane ATPase and inhibit Mg2+‐activated ATPase. The substrate specificity of plasmamembrane ATPase is much greater than the substrate specificity of mitochondrial ATPase.
Effects of Glyphosate on Metabolism of Phenolic Compounds
Authors: HOAGLAND ROBERT E. , DUKE STEPHEN O. , ELMORE C. DENNIS 
Published: April 2006

AbstractAmounts of extractable phenylalanine ammonia‐lyase (PAL; E.C. 4.3.1.5) activity increased in the axes of 3–day‐old, dark‐grown soybean seedlings [Glycine max (L.) Merr.] shortly after the seedlings were transferred to glyphosate [N‐(phosphonomethyl)‐glycine] solutions. The stimulation of PAL activity in herbicide‐treated tissue (as compared to control tissue) was detectable as early as 12 h after treatment, whereas growth inhibition (length, fresh weight and dry weight) was not significantly affected until 24 h on a fresh‐weight basis and at 48 h on a dry‐weight basis. PAL activity increased with time (12–72 h) in herbicide‐treated axes when expressed as activity per gram fresh weight, specific activity, and on a per axis basis. PAL activity stimulation correlated positively with glyphosate concentration from 10–4 to 10–3M. PAL activity in control tissues remained nearly constant over the sampling period (12–72 h). Total alcohol‐soluble hydroxyphenolic compound levels in treated axes were not significantly different from the control at any sampling period. The total soluble amino acid pool showed a general decrease with time in glyphosate‐treated tissues. The phenylalanine pool was lowered with treatment time and the ammonia concentration (per g fr. wt. basis) was increased after treatment. No significant differences were noted in the concentration of soluble protein of glyphosate‐treated tissue when compared to controls. Visual effects (stunting, lack of secondary root formation, and necrotic areas) of glyphosate were more obvious in the root than in the hypocotyl. Analysis of various chemical constituents substantiated that other glyphosate effects were more clearly demonstrable in the root than in the hypocotyl or in the intact axis. On a per root basis glyphosate markedly increased PAL activity while reducing free phenylalanine, free tyrosine, soluble hydroxyphenolics, total free amino acids and ammonia content. The effect of glyphosate in the root was greatest on phenylalanine content, reducing it five‐fold. The results indicate that glyphosate could exert its effect through either induction of PAL activity and/or inhibition of aromatic amino acid synthesis.
Nitrogen Fixation Associated with Sand Grain Root Sheaths (Rhizosheaths) of Certain Xeric Grasses
Authors: WULLSTEIN L. H. , BRUENING M. L. , BOLLEN W. B. 
Published: April 2006

AbstractNitrogen fixation (acetylene reduction) was found to be associated with sand grain root sheaths (rhizoseaths) occurring on the following xeric grasses: Oryzopsis hymenoides (Roem. and Shult.) Ricker, Agropyron dasystachyum (Hook.) Scrib., Stipa comata Trin. and Rupr., and Aristida purpurea Nutt. Acetylene reduction rates associated with whole plant specimens of these species varied from 515 to 920 nmol C2H4/(g dry wt.) × (6 days). Nitrogenase activity was shown to be associated with the rhizosheaths. Bacillus polymyxa‐like nitrogen fixers were isolated from the rhizosheaths of each grass. The isolates reduced acetylene and assimilated 15N2.
Changes in Ribonuclease Activity of Wheat Plants during Water Stress
Authors: YI CHOK WANG , TODD GLENN W. 
Published: April 2006

AbstractRNases from control and water‐stressed wheat seedlings were purified by ion exchange chromatography, gel filtration and gel electrophoresis. The enzyme appeared to be identical from both treatments and only one species was found. Subcellular distribution between soluble and particulate fractions was not changed by water stress treatment. Total quantity of RNase per plant was similar in control and water‐stressed plants, although since the dry weight of treated plants was less, the activity per gram was significantly higher. Crude homogenates of leaf extracts contained an RNase inhibitor with a greater amount being present in control leaves. No evidence was found to indicate that new types of RNases are synthesized during water stress.
Osmotic Requirement for Shoot Formation in Tobacco Callus
Authors: BROWN DANIEL C. W. , LEUNG DAVID W. M. , THORPE TREVOR A. 
Published: April 2006

AbstractTobacco callus grown on medium containing 3% sucrose (w/v) shows optimum growth and produces the highest number of shoots; whereas cultures grown on medium with lower or higher sucrose levels show a reduced growth rate and capacity to form shoots. Cultures grown on a low sucrose containing medium produce a high number of shoots only if the medium is supplemented with mannitol to give the same water potential as that of the 3% sucrose medium. Mannitol cannot replace the sucrose requirement for growth. Increased levels of Bacto Agar, tricarboxylic acid cycle intermediates and amino acids added to the medium do not promote shoot formation or replace the carbohydrate requirement for that process. The success in partially replacing the sucrose requirement for shoot formation with mannitol supports the view that part of the tissue carbohydrate is acting in an osmoregulatory role. This finding is further interpreted in terms of the hypothesis of turgor‐driven growth and cell expansion.
Seasonal and Experimentally Induced Changes in the Ultrastructure of Chloroplasts of Pinus silvestris
Authors: MARTIN BJÖRN , ÖQUIST GUNNAR 
Published: April 2006

AbstractThe ultrastructure of chloroplasts in mesophyll cells of Pinus silvesris was examined under the electron microscope. Secondary needles were regularly sampled from a tree in a natural stand for one year. Primary needles from one‐year‐old seedlings exposed to frost hardening and dehardening conditions in a controlled environment chamber were also studied. These seedlings were exposed to 8 or 55 W m‐2. All needles were put in fixative at the different sampling dates and stored in a refrigerator until they were prepared for electron microscopy at the end of the experimental period.During the summer the choroplasts were symmetrically shaped and heavily loaded with starch. The membrane systems were well developed and consisted of both grana and stroma thylakoids. In autumn and during early artificial frost hardening the starch content was reduced, the chloroplasts appeared amoeboid and membrane‐free stroma regions were seen. Later the chloroplasts became swollen and aggregated in one part of the cell. Starch was lost and the chloroplasts aggregated earlier at 8 W m‐2 than at 55 W m‐2. During winter the stroma thylakoids were first reduced in number and later even the grana thylakoids were damaged, resulting in mostly disorganized single membranes. Also the chloroplast envelope disappeared. In spring and early summer the chloroplasts migrated to the proximity of the cell walls. The membrane systems were reorganized and starch accumulated. During the first days of artificial dehardening the photosynthetic membranes were severely damaged, especially at 55 W m‐2, but soon new membranes were formed. Starch accumulated earlier at 55 than at 8 W m‐2.The reported ultrastructural variations are discussed in relation to functional and biochemical fluctuations caused by the season or by artificial variations in the climate as demonstrated earlier.
The Effect of Benzyladenine on Changes in Nuclease and Protease Activities in Intact Bean Leaves during Ageing
Authors: NAITO KUNIHIKO , IIDA AKIRA , SUZUKI HIROSHI , TSUJI HIDEO 
Published: April 2006

AbstractPrimary leaves of intact bean plants (Phaseolus vulgaris L.) were treated with benzyladenine (BA) at different stages during growth. Changes in DNase, RNase, and proteas activities in the leaves were followed. Unlike the case of various excised tissues, cytokinin raised the activities of these hydrolases in intact bean leaves. Because BA elevated the levels of DNA, RNA, and protein in intact leaves, it may stimulate both synthesis and decomposition of these cellular constituents. The hydrolase activities showed differential responses to BA according to the age at which the leaf received the hormone treatment.
Effects of Oxygen Concentration on the Respiration of Excised Root‐Tip Segments of Maize and Rice, and of Germinating Grains of Rice and Buckwheat
Authors: GIRTON RAYMOND E. 
Published: April 2006

AbstractIn view of the known tolerance of rice (Oryza sativa) to wet soils, in contrast to maize (Zea mays), a comparison of the respiratory responses of the two plants to different O2 concen trations was made. It was found that if the O2 concentration was raised to 100%, an increase was observed of the O2 input and the CO2 output in maize root‐tip segments and in germinating grains of rice and also in buckwheat (Fagopyrum sp.). In marked contrast rice root‐tip segments, when treated with 100% O2, exhibited no such increase over the air controls. Increased O2 concentrations decreased RQ values ranging from 2.0 (with 5% O2) to 0.86 (with 100% O2). Air‐control RQ values were lowest with maize roots (0.9) and highest with germinating rice grains (1.0). Rice grains also exhibited the highest F/R ratio (0.85), and buckwheat grains the lowest (0.45). The addition of sucrose to maize root tips tended to promote fermentation (CO2 output) rather than aerobic respiration (O2 input).
Acides aminés libres et protéiques des divers types de rameaux du Periploca graeca: Rôle dans la circumnutation des tiges volubiles et compartimentation intracellulaire
Authors: MELIN D. , VALLEE J. C. , VANSUYT G. , PREVOST J. 
Published: April 2006

Abstract Free and Bound Amino Acids in the Different Shoot Types of Periploca graeca: Role in the Circumnutation of Twining Shoots, and Cellular Compartmentation.A study has been made of amino acids of wall proteins, cytoplasmic TCA insoluble proteins and proteins of organelles in growing tissues from three types of shoots: short upright, twining, and creeping, all carried by the same specimen of Periploca graeca L. Each shoot type presents a specific pattern. The twining shoots are very rich in cytoplasmic TCA‐insoluble proteins. The upright shoots distinguish themselves by a high level of proteins in the organelles and in the cell‐wall. However, the composition of wallproteins is almost the same in the three types of shoots. This result excludes the existence of particular wall proteins (extensin, for example) in the twining and rapidly growing shoots. In these shoots the high level of free prolin is not a consequence of low incorporation in the proteins. Distribution of prolin, aspartic acid and glutamic acid between the cellular compartments (wall, hyaloplasm and organelles) has a specific pattern in each shoot type.
Nitrate Uptake by Manganese‐Deficient Lemon Plants
Authors: LERER MICHAEL , BAR‐AKIVA AVIGDOR 
Published: April 2006

AbstractThe uptake of nitrate and water was followed in Eureka lemon (Citrus limon (L.) Burm. f.) plants grown in solution culture in a greenhouse under short (3–6 months) and long‐term (22–24 months) Mn‐nutrition stress. Uptake was determined from depletion in the nutrient solution.Under short‐term stress, manganese‐deficient plants absorbed 14.5% more nitrate and 3.4% more water than the control plants, on a weight basis. Under long‐term stress there was a three‐fold increase in nitrate and a two‐fold increase in water uptake in the Mn‐deficient plants.The intensive nitrate uptake under Mn‐deficiency stress was more spectacularly demonstrated in plants which were exposed also to low nitrogen supply. The low‐nitrogen Mn‐deficient plants absorbed more nitrate, had less stunted growth and developed fewer visible symptoms of both N and Mn deficiencies than high‐nitrogen Mn‐deficient plants.