bluuebunny/crossref_metadata_2025_split huggingface dataset:
Light induced transpiration in a chlorophyll deficient mutant of Hordeum vulgare
Authors: SKAAR H. , JOHNSSON A. 
Published: April 2006

AbstractA chlorophyll deficient mutant of Hordeum vulgare L. was investigated with respect to its transpiration response to light pulses. Broad band blue light. 380–500 nm, caused a significant transpiration response, while broad band red light did not. The transpiration response to changes in the ambient CO2‐concentration was the same in the chlorophyll deficient mutant as in green plants. The absence of a transpiration response to red light in the mutant was therefore not the result of a defective CO2‐response. It is concluded that the specific blue light response is not mediated via photosynthetic CO2‐fixation. The nature of the blue light response is discussed.
Nutrient utilization and requirement under photoheterotrophic growth of Marchantia polymorpha: Improvement of the culture medium
Authors: KATOH KENJI , ISHIKAWA MOMOYO , MIYAKE KEIKO , OHTA YOSHIMOTO , HIROSE YOSHIO , IWAMURA TATSUICHI 
Published: April 2006

AbstractPreviously we reported on a suspension culture of chlorophyllous cells of a liverwort, Marchantia polymorpha L., under photoheterotrophic conditions. The chemically defined medium was a modified Murashige and Skoog's medium, which contained, besides glucose, inorganic salts, a growth regulator (2,4‐D), and twenty‐four organic compounds as micro constituents. Because of this complexity, we undertook a simplification of the medium. Having examined the utilization of the major nutrients and the requirements for the micro constituents, we have succeeded in improving the medium. The new medium contains phosphate at 3.13 mM and only eight out of the twenty‐four original micro organic constituents. In this new medium, the cells grow under a well‐balanced nutritional condition, with richer chlorophyll and at a higher rate during the exponential phase than in the original medium.
Influence de quelques acides aminés libres de l'ovule sur la croissance et le développement cellulaire in vitro du tube pollinique chez Juniperus communis (Cupressaceae)
Authors: DUHOUX EMILE , THI ANH THU PHAM 
Published: April 2006

AbstractInfluence of some free amino acids of the ovule on growth and cellular development of the pollen tube of Juniperus communis L. in vitro.The extraction and analysis of free amino acids show that a partial complementary relationship exists between the amino acids of the pollen and those of the ovule of Juniperus communis. The main free amino acids of the pollen are threonine, proline, arginine and γ‐aminobutyric acid; those of the ovule are threonine, serine, alanine, citrulline and glycine. The addition of the main amino acids of the ovule in the pollen culture media increased the growth and the cell development of pollen tubes cultured in vitro. This indicates the nature of the correlations which exist between the male and female gametophyte of Juniperus communis.
Effects of light on terpene hydrocarbon synthesis in Pinus pinaster
Authors: GLEIZES MICHEL , PAULY G. , BERNARD‐DAGAN C. , JACQUES R. 
Published: April 2006

AbstractThe biosynthesis of terpene hydrocarbons has been investigated in maritime pine (Pinus pinaster Ait.) seedling primary leaves under light and darkness and with different precursors. Impossible in darkness, the synthesis of monoterpenes (mainly α‐ and β‐pinene) is strongly activated by light. Only 14C‐carbonate and 14C‐acetate can be incorporated into monoterpenes. Activation by light is comparatively much more effective for seedling leaves previously cultivated under short days than in leaves from seedlings given long days. The spectral bands which are efficient for the synthesis of monoterpenes are located around 480 and 685 nm with 14C‐carbonate and 480 and 630 nm with l‐14C‐acetate. Furthermore, this light activation does not occur if leaf pieces instead of whole leaves are used for the incorporation experiments. When 2‐14C‐mevalonic acid and 1‐14C‐isopentenyl pyrosphosphate are applied as precursors, no radioactivity is recorded in monoterpene hydrocarbons even after light exposures. In contrast, sesquiterpene hydrocarbons (caryophyllene and humulene) are easily synthesized under light or darkness in intact or fragmented leaves from the different precursors of photosynthetic or exogenous origin. From these results the compartmentalization in the synthesis of C10 and C15 hydrocarbons appears clear. There is a metabolic cooperation between the photosynthetic tissues and the specific site of elaboration of C10 hydrocarbons, which site is located in the parts where the epithelial cells of resin ducts are functional. The synthesis of sesquiterpene hydrocarbons takes place in the whole leaf without activation by light.
Thigmomorphogenesis: Evidence for a translocatable thigmomorphogenetic factor induced by mechanical perturbation of beans (Phaseolus vulgaris)
Authors: ERNER Y. , BIRO R. , JAFFE M. J. 
Published: April 2006

AbstractMechanical perturbation of bean (Phaseolus vulgaris L.) internodes results in reduced elongation and increased diameter of the internodes (thigmomorphogenesis). Perturbation of a single lower internode results in thigmorphogenesis in that internode and all of those internodes above it, the degree of which depends on the age (size) of the internodes and the frequency of perturbation. Application of ethephon to the internodes mimics mechanical perturbation. Early removal of the shoot tip or the cotyledons does not effect thigmomorphogenesis, indicating that those organs do not exert control over the response. Mechanical perturbation of one plant of a pair grafted together at the first internodes results in thigmomorphogenesis in both plants. This indicates the transport of some factor from the mechanically perturbed donor to the non‐treated receiver. Evidence is presented to support the contention that ethylene is not this transportable factor.
Effect of some disaccharides, hexoses and pentoses on nitrate reductase, glutamine synthetase and glutamate dehydrogenase in excised pea roots
Authors: SAHULKA JOSEF , LISÁ LUDMILA 
Published: April 2006

AbstractThe effects of exogenous sucrose, lactose, d‐glucose, d(‐)fructose, d‐galactose, d‐mannose, l‐sorbose, l‐arabinose and d‐xylose on nitrate reductase (NR), glutamine synthetase (GS) and glutamate dehydrogenase (GDH) levels, on anaerobic nitrite production and on respiratory O2 consumption were studied in excised roots of pea (Pisum sativum L. cv. Raman). Sucrose, glucose and fructose increase NR and GS levels and decrease GDH level (when compared with roots cultures without any sugar) at all concentrations used, but the extent of this effect varies. NR induction is enhanced by all sugars within the concentration range studied. Precultivation of roots with mannose and galactose results in an increase in anaerobic nitrite production in a medium consisting of phosphate buffer and KNO3. GS reaches its maximum at lower sugar concentrations, this fact being especially clear‐cut with galactose. The decrease in GS level observed in roots cultured without sucrose is enhanced by higher sorbose concentrations. The increase in GDH level occurring in roots cultured without sucrose is depressed by low galactose and mannose concentrations but enhanced by high galactose, mannose, xylose and a wide range of sorbose concentrations. Lactose exerts only slight influence on the enzymes. The effects of sugars are in no case consistent with their effect on respiratory O2 consumption which is most pronounced with NR.The above results show that the effects of sugars on NR, GS and GDH are not mediated by one universal mechanism.
Sequential extraction of chlorophyll from chlorophyll‐protein complexes in lyophilized pea thylakoids with solvents of different polarity
Authors: ÖQUIST GUNNAR , SAMUELSSON GÖRAN 
Published: April 2006

AbstractLyophilized chloroplasts of Pisum sativum (pea) have been extracted with petroleum ether of different polarity (obtained by adding varying amounts of ethanol to the petroleum ether). Extracted thylakoids have then been solubilized by sodium dodecyl sulphate (SDS) and chlorophyll‐protein complexes have been isolated by polyacrylamide gel electrophoresis (PAGE). Absorption‐ and low temperature fluorescence emission spectro‐scopy have been used to characterize thylakoids and purified chlorophyll‐protein complexes.Weakly polar solvents extracted mainly chlorophyll a. SDS‐PAGE scan profiles of similarly extracted thylakoids contained no photosystem II chlorophyll a reaction center antennae (CP‐an) and the amount of photosystem I chlorophyll a reaction center antennae (CP‐a1) was reduced as compared with an unextracted control. This was due partly to the extraction of chlorophyll a prior to SDS‐PAGE, and partly to the increased solubilization of chlorophyll a by SDS as a result of β‐carotene extraction. By increasing the polarity of the solvent CP‐a1 also disappeared in the scan profile, leaving only the light‐harvesting chlorophyll a/b‐protein complex (CP‐a/b) and SDS complexed chlorophyll.From these results we conclude that the chlorophyll molecules in the reaction center antennae are relatively more hydrophobically associated than the molecules in the light‐harvesting CP‐a/b complex. The chlorophyll a of CP‐au and the far red absorbing chlorophyll a fraction of CP‐a1 appear to be the most hydrophobically associated chlorophyll molecules.
On the role of ß‐carotene in the reaction center chlorophyll a antennae of photosystem I
Authors: OQUIST By GUNNAR , SAMUELSSON GÖRAN , BISHOP NORMAN I. 
Published: April 2006

AbstractAbsorption and low temperature fluorescence emission spectra were measured on chloroplast thylakoids and on purified reaction center chlorophyll a‐protein complexes of photosystem I, CP‐a1. A clear association between the presence of ß‐carotene and the occurrence of far red absorbing and emitting chlorophyll a components of the reaction center antennae of photosystem I was demonstrated. For this study chloroplasts and CP‐a1 were obtained from normal and carotenoid deficient plant material of various sources. The experimental material included 1) lyophilized pea chloroplasts extracted with petroleum ether, 2) the carotenoid deficient mutant C‐6E of Scenedesmus obliquus and 3) wheat chloroplasts derived from normal and SAN‐9789 treated plants. Removal of carotenoids, most likely principally ß‐carotene, caused a loss of long wavelength absorbing chlorophylls in chloroplasts and purified CP‐a1, and the loss or diminution of the long wavelength peak seen in the low temperature fluorescence emission spectrum. This association between ß‐carotene and special chlorophyll a forms may explain both the photoprotective and antenna functions ascribed to ß‐carotene. In the absence of carotenoids in wheat and in the Scenedesmus mutant, the chlorophyll a antenna of photosystem I was extremely photosensitive. A triplet‐triplet resonance energy transfer from chlorophyll a to ß‐carotene and a singlet‐singlet energy transfer from excited ß‐carotene to chlorophyll would explain the photoprotective and antenna functions, respectively. The role of this association in determining some of the fluorescence properties of photosystem I is also discussed.
Growth of corn in saline waters
Authors: SIEGEL S. M. , SIEGEL B. Z. , MASSEY JANE , LAHNE PAMELA , CHEN JUNG 
Published: April 2006

AbstractEight cultivars of Zea mays plus the wild species Zea diploperennis were screened for seedling saline tolerance up to 3.2% NaCl. The best performances were given by the cultivars Mo 17 and commercial Hawaiian Super Sweet Hybrid. These two were then field grown on coral‐cinder beds using drip irrigation with fresh of half‐strength sea water (1.5–1.7% dissolved solids). Growth and chemical data for Mo 17 at 12 weeks show reduced growth but the same percentage dry matter. Ash, protein and total sulfur were higher in saline plants, silica and total phosphorus lower. Na, K. Mg, and Cl were elevated and Ca reduced slightly. Fe was also increased in saline plants. Both Mo 17 and Super Sweet Hybrid corn flowered and produced seed which retained essentially normal viability both in fresh and salt water.
The effect of fluoride on the growth and fatty acid composition of Sphagnum fimbriatum at two temperatures
Authors: SIMOLA LIISA KAARINA , KOSKIMIES‐SOININEN KRISTIINA 
Published: April 2006

AbstractThe fatly acid composition of different lipid fractions (neutral, glyco‐ and phospholipids) was studied in Sphagnum fimbriatum Wils, gametophytes grown in aseptic cultures at two temperatures (15°C and 25°C). The effect of a growth‐retarding concentration (0.1 mM) of KF was also investigated.Fifteen‐day treatment with KF affected the fatty acid composition more strongly at the higher than at the lower temperature. The proportion of palmitic acid (16:0) increased but the proportion of linoleic (18:2) decreased in all the lipid fractions, and that of linolenic (18:3) acid decreased in the fractions containing glyco‐ and neutral lipids. This indicates that the fluoride ions inhibit lengthening of the fatty acid chain.Compared with gametophytes grown at 25°C, material cultivated at 15°C had a much higher proportion of a highly unsaturated fatty acid, linolenic acid (18:3), in all the lipid fractions, but a lower proportion of oleic acid (18:1) in the neutral and phospholipids, and a lower proportion of linoleic (18:2) acid in all three fractions.
Physiological studies on pea tendrils
Authors: JAFFE M. J. , SHOTWELL M. 
Published: April 2006

AbstractWhen tendrils which have been dark adapted for 3 days are mechanically stimulated, they will only coil appreciably if they are irradiated with light. A spectral response curve suggests that this is a blue light effect. Red or far red light do not modulate this response, but a high intensity flash of blue white light given before the actinic blue light blocks coiling for 30 min. The dark‐adapted tendril, which has not been previously rubbed, has the ability to store the tactile sensory information for about 60 min, but loses it if it is not irradiated within 120 min after mechanical perturbation.
On simultaneous transport of water and solute through plant cell membranes: Evidence for the absence of solvent drag effect and insensitivity of the reflection coefficient
Authors: PALTA JIWAN P. , STADELMANN EDUARD J. 
Published: April 2006

AbstractThe simultaneous efflux of tritiated water and 14C labelled ethanol from inner epidermal cells of the bulb scale of Allium cepa was measured with a specially designed efflux chamber. It was found that water and ethanol moved essentially independently. Rates of efflux of tritiated water and 14C ethanol were essentially the same in the presence or absence of a simultaneous influx of water.Using the same technique the efflux of tritiated water from the epidermal cells was measured during a simultaneous flow of nonlabelled ethanol. When tritiated water and ethanol moved in opposite directions, the water permeability values became slightly reduced depending upon the concentration of ethanol. When ethanol and tritiated water moved in the same direction, however, no effect on water permeability values could be detected. These results are best explained by the molecular theory of diffusion across lipid bilayer membranes, and are consistent with the above findings of lack of interaction between water and ethanol as they are transported across the cell membrane.In another study, the solute permeability coefficients (Ks) for non‐electrolytes such as urea and methyl urea were measured by plasmolyzing the epidermal cells and transferring them to equimolal solutions of urea and methyl urea. This method was also used to measure the reflection coefficient (σ) for these nonelectrolytes. The Ks values for methyl urea were 16 times greater than the ones for urea. The values of σ for both of these solutes, however, were very close to 1.Using the Ks data available in the literature for the subepidermal cells of the Pisum sativum stem basis, the σ values were calculated for malonamide, glycerol, methyl urea, ethyl urea, dimethyl urea, and formamide. Again the Ks values for these nonelectrolytes varied by several orders of magnitude, whereas all σ values were found to be close to 1.These findings point out that σ is an insensitive parameter and that Ks, the solute permeability constant, has to be used for characterizing solute transport through the membrane. The present study shows that fast (e.g. ethanol, formamide) as well as slowly permeating molecules do not interact with water as they are transported across the cell membrane. Aqueous pores for the simultaneous transport of water and solutes, therefore, are absent in the plant cell membranes investigated here.
Hormonal regulation of secondary abscission in pear pedicels in vitro
Authors: PIERIK R. L. M. 
Published: April 2006

Abstract In vitro cultivated pear, Pyrus communis L. cv. Beurré Hardy, pedicels cut above their primary abscission layer can form a secondary abscission layer, especially under the influence of auxins or cytokinins in the culture medium. The maximum percentage of abscission reached by auxin application was always higher than that by cytokinin. The presence of the flower was of no consequence to the abscission. Characteristic differences in abscission were observed between pear and apple pedicels. In contrast to apple (1) secondary abscission in pear could also be induced by cytokinins, and (2) the site of abscission in pear was dependent on the auxin concentration. At lower auxin concentrations abscission was induced in the basal parts of the pedicels inserted in the medium, whereas at higher auxin concentrations the abscission layer was formed in the terminal parts of the pedicels above the culture medium. A clear effect of gibberellins, ABA and CEPA could not be detected.
Effects of various buffers, 3‐(3,4‐dichlorophenyl)‐1,1‐dimethylurea (DCMU) and NaN3 on menadione mediated photophosphorylation in isolated chloroplasts
Authors: DURAINI M. USAMAH , HAMLIN LEIF , TILLBERG JAN‐ERIC 
Published: April 2006

AbstractThe effects of DCMU and NaN3 were studied on menadione‐mediated photophosphorylation in broken spinach chloroplasts kept in low oxygen tension in Tricine or HEPES buffers at either high or reduced irradiances. – (A) At high irradiance (131 W. m−2) and absence of NaN3 the ATP formation was inhibited by DCMU regardless of the type of buffer used. – (B) At high irradiance and presence of NaN3 some concentrations of DCMU stimulated, whilst others inhibited the ATP formation in a HEPES buffer. The ATP formation was predominantly inhibited by DCMU in a Tricine buffer. – (C) At reduced irradiance (57 W. m−2) the chloroplasts in a HEPES buffer were almost insensitive towards DCMU both in the presence and absence of NaN3. – (D) Chloroplasts in a Tricine buffer were slightly stimulated in their ATP formation by DCMU at reduced irradiance either with or without the presence of NaN3 in the experimental medium. When menadione acts as a terminal electron acceptor, oxygen is consumed on its reoxidation. The results indicate that this process may occur with oxygen released by the splitting of water as the main oxidant. – The data also demonstrate the importance of caution when selecting buffering substances as well as when choosing light intensities for experiments on photophosphorylation in chloroplasts.
Redistribution of potassium, boron, iron, magnesium and calcium in apple trees determined by an indirect method
Authors: Van GOOR BEREND J. , Van LUNE PIET 
Published: April 2006

AbstractThe intensity of the process of redistribution of the elements potassium, boron, iron, magnesium and calcium was determined by following the rate of accumulation of these elements into the fruits of apple (Malus domestica Borkh.) trees. The determination is based on the assumption that the process of primary distribution via the xylem becomes relatively unimportant with respect to supply along the phloem during the period of fruit growth. Thus a decreasing rate of accumulation for a phloem‐immobile and xylem‐mobile element will be seen during this period of growth, while an element which is mobile in both pathways will give a linear rate of accumulation when the supply by the root does not alter too much.In addition, the ratios of the contents in fruits and leaves were used as an indicator of the relative mobility in redistribution.In these experiments with apple, potassium and boron showed a high mobility. Magnesium and especially calcium showed a much lower mobility in redistribution than in the primary rate of supply. Iron was intermediary. The results, especially for boron and magnesium, are in contradiction to some of the data in the literature. Further studies are needed before these contrasting results can be explained.
Inhibition of photosynthetic electron transport and formation of inactive chlorophyll in winter stressed Pinus silvestris
Authors: ÖQUIST GUNNAR , MARTIN BJÖRN 
Published: April 2006

AbstractKinetics of fluorescence at room temperature, electron transport and photooxidation of P700 and cytochrome f have been studied in chloroplasts isolated from active and winter stressed Pinus silvestris. The winter stress induced block in the electron transport chain between the two photosystems is close to the site of plastoquinone, since winter stress and DCMU caused the same type of inhibition of the reoxidation of the primary electron acceptor Q of photosystem II. No winter inhibition of the electron transport between cytochrome f and P700 was observed.Time course studies of P700 photooxidation in chloroplasts of active and winter stressed pine have shown that the photosynthetic unit size must be about equal in the two types of chloroplasts. An apparent increase of the photosynthetic unit size was induced by winter stress, as revealed by the high chlorophyll/P700 ratio of winter stressed pine. The phenomenon is explained by the formation of photosynthetically inactive chlorophyll.Low‐temperature fluorescence emission spectra were recorded when either chlorophyll a (433 nm) or chlorophyll b (477 nm) were preferentially excited. Winter stress induced the formation of a chlorophyll a fraction emitting at 673 nm. This chlorophyll is most likely derived from the chlorophyll a antennae of the two photosystems, and it probably contributes to the photosynthetically inactive pool of chlorophyll in winter stressed pine. The light harvesting chlorophyll a/b complex is relatively resistant to winter stress.