bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermoluminescence and Delayed Luminescence Investigation of the Green Alga, Chlamydobotrys stellata
Authors: Wiessner W. , Mende D. , Deak Z. , Demeter S. 
Published: February 2014

AbstractThermoluminescence and delayed luminescence investigations of the autotrophically and photoheterotrophically cultivated green alga, Chlamydobotrys stellata, demonstrated that both the thermoluminescence and delayed luminescence yields are much lower in the photoheterotophic algae than in the autotrophic ones due to an efficient luminescence quenching of unknown mechanism. The relative contributions of the so called Q (S2Q−A charge recombination) and B (S2Q−B and S3Q−B charge recombinations) thermoluminescence bands to the glow curve as well as the QA(S2Q−B charge recombination) and QB (S2Q−B and S3Q−B charge recombinations) delayed luminescence components to the delayed luminescence decay of autotrophically and photoheterotrophically cultivated Chl. stellata were compared using a computer assisted curve resolution method.It was found that, while in the autotrophic cells the area of the B band was considerably larger than of the Q band, in photoheterotrophic cells the Q band was more effectively charged than the B band.In the delayed luminescence decay curves measured in the seconds to minutes time region the amplitude of the QA component relative to that of the QB component was larger in the photoheterotrophic cells than in the autotrophic ones.These observations demonstrate that, after light‐induced charge separation in the photosystem II reaction centers of autotrophic cells, electrons are “quasipermanently” stored mainly in the secondary quinone acceptor pool, QB but in the nonquenched photosystem II reaction centers of photoheterotrophic cells the main reservoir of electrons is the primary quinone acceptor, QA. This behaviour indicates an inhibition of electron transport in the photoheterotrophic alga at the level of the secondary quinone acceptor, QB.
Water Status of Green and Blue‐green Phycobionts in Lichen Thalli after Hydration by Water Vapor Uptake: Do They Become Turgid?
Authors: Büdel B. , Lange O. L. 
Published: February 2014

AbstractIt is known from previous investigations that dry lichens with green algae are able to recover net photosynthesis through rehydration with water vapor, whereas all blue‐green lichens tested so far lack this ability. The REM micrographs of the present study show that the green phycobionts (Trebouxia spec.) of Ramalina maciformis become turgid only after water vapor uptake. In contrast, the blue‐green phycobionts (Nostoc spec.) of Peltigera rufescens do not differ in appearance from the dry state, even when the thallus has reached equilibrium with the water vapor‐saturated air; they require liquid water for turgidity. It is hypothesized that, after humidity hydration, water content is not sufficient for reestablishment of a functioning osmotic cell system in the blue‐green phycobiont.
Immunological Evidence of Connexin‐like Proteins in the Plasma Membrane of Vicia faba L.
Authors: Hunte Carola , Schnabl Heide , Traub O. , Willecke K. , Schulz Margot 
Published: February 2014

AbstractPlasma membranes from three week old leaves of Vicia faba L. were enriched by aqueous two‐phase partitioning to high purity. Plasma membrane proteins were immunoblotted with polyclonal, monospecific antibodies raised against mouse liver connexins (cx) 32 and 26. Immunostaining after treatments with cx 32 antibodies revealed the existence of a 29 kDa protein, clearly enriched in the plasma membrane fraction. An additional immunoreactive band of 20 kDa, possibly a degradation product of the 29 kDa protein, was found in the soluble fraction. When immunoblots were incubated with cx 26 antibodies, a 40 kDa band with a strong immunoresponse appeared, assumed to present the dimeric form of a 21 kDa, cx 26‐like plant protein. The monomeric form could be only obtained when intact leaf material or mesophyll protoplasts from three week old plants were directly SDS‐extracted. Furthermore, in young, one week old leaves, the monomer seems to exist in larger amounts, together with another crossreacting 35 kDa protein. The 29 kDa (cx 32‐related) as well as the 40 kDa (cx 26‐related) polypeptide is obviously located in the plasma membrane. The 40 kDa protein has to be considered as a new connexin‐like plant protein.
Growth Characteristics and Elicitor‐induced Reactions of Photosynthetically Active and Heterotrophic Cell Suspension Cultures of Lycopersicon peruvianum (Mill.)*
Authors: Beimen Andrea , Witte L. , Barz W. 
Published: February 2014

AbstractCell suspension cultures of Lycopersicon peruvianum (Solanaceae) were established as well‐growing photoautotrophic, photomixotrophic and heterotrophic cultures and their growth parameters were characterized. Elicitor‐induced responses of these cultures to the tomato pathogen Fusarium oxysporum f. sp. lycopersici were investigated after treatment of cells with autoclaved mycelium and culture filtrate of this fungus. The dominant reaction was an enhanced incorporation of phenolic constituents in the plant cell wall. Among the nine phenolics released by alkaline hydrolysis the most prominent compounds were p‐hydroxybenzaldchyde, vanillin, p‐coumaroyltryamine, feruloyltyramine, p‐coumaric acid and ferulic acid. Phenolic incorporation in cell walls resulted in increased stability of cells against protoplasting with microbial enzymes. Chlorogenic acid, as the main soluble phenolic compound, showed differential accumulation in the three cell cultures lines as well as an elicitor‐induced transient decrease. In heterotrophic cells decrease of chlorogenate occurred concomitant with accumulation of caffeoyl‐ and p‐coumaroylshikimate as well as increased activities of p‐coumaroyleoenzyme A: shikimic acid p‐coumaroyltransferase. Upon elicitation increased activities of phenylalanine ammonia lyase and changes in peroxidase activities wore also detected. Sesquiterpenoid phytoalexines were not produced by either one of the cell culture lines and levels of tomatine were not significantly affected by elicitation.
Adenosine 5‘‐Phosphosulfate Sulfotransferase from Norway Spruce: Biochemical and Physiological Properties*
Authors: Suter Marianne , Tschanz A. , Brunold Chr 
Published: February 2014

AbstractBiochemical and physiological properties of adenosine 5′‐phosphosulfate sulfotransferase, a key enzyme of assimilatory sulfate reduction, from spruce trees growing under field conditions were studied. The apparent Km for adenosine 5′‐phosphosulfate (APS) was 29 ± 5.5μM, its apparent Mr was 115,000. 5′‐AMP inhibited the enzyme competitively with a Ki of 1 mM, but also stabilized it. MgS04 at 800 mM increased adenosine 5′‐phosphosulfate sulfotransferase activity by a factor of 3, concentrations higher than lOOOmM were inhibitory. Treatment of isolated shoots with nutrient solution containing 1 or 2 mM sulfate, and 3 or 10 mM glutathione, respectively, induced a significant decrease in extractable adenosine 5′‐phosphosulfate sulfotransferase activity over 24h, whereas GSH as well as S2‐ up to 5mM cysteine and up to 200 mM SO32‐ had no effect on the in vitro activity of the enzyme. As with other enzymes involved in assimilatory sulfate reduction, namely ATP sulfurylase (EC 2.7.7.4), sulfite reductase (EC 1.8.7.1) and O‐acetyl‐L.‐serine sulfhydrylase (EC 4.2.99.8), adenosine 5′‐phosphosulfate sulfotransferase was still detected at appreciable activities in 2‐ and 3‐year‐old needles. Adenosine 5′‐phosphosulfate sulfotransferase activity was low in buds and increased during shoot development, parallel to the chlorophyll content. The enzyme activity was characterized by an annual cycle of seasonal changes with an increase during February and March.
Homologies in the Structural Genes Coding for Sulphate Reducing Enzymes from Higher Plants and Prokaryotes*
Authors: Gisselmann G. , Niehaus Andrea , Schwenn J. D. 
Published: February 2014

AbstractThe structural genes of enterobacteria encoding for the enzymes involved in the assimilatory reduction of sulphate (“cys genes”) were used in order to identify homologous genes from phototrophic cyanobacteria and higher plants. By Southern hybridisation of genomic DNA from the higher organisms with the cys DNA‐probes derived from Escherichia coli, discrete restriction fragments were found in higher plants and in cyanobacteria indicating the occurrence of related DNA. Two of the cyanobacterial genes were cloned and identified by DNA and amino acid sequence comparison as the structural genes encoding the PAPS‐reductase (EC 1.8.4.‐) and the ferredoxin: sulphite‐reductase (EC 1.8.7.1). The nucleic acid of both genes showed stretches of highly conserved bases in regions of the sequences which are regarded as the functionally important domains of the gene products.
The Effect of Pressurized Gas Transport on Nutrient Uptake During Hypoxia of Alder Roots*
Authors: Grosse W. , Meyer Doris 
Published: February 2014

AbstractThe uptake of nitrate, sulphate, phosphate, and potassium from a nutrient solution by young alder trees (Alnus glutinosa) was reduced during hypoxia. Such a decrease of ion uptake was not observed when the internal oxygen supply of the tree roots was improved by pressurized gas transport. These results demonstrate the beneficial effect of this gas transport phenomenon on the nutrition of trees growing on wet sites characterized by anaerobic soil.
The Role of the Epidermis in the Control of Elongation Growth in Stems and Coleoptiles
Authors: Kutschera U. 
Published: February 2014

AbstractThe peripheral cell wall(s) of stems and coleoptiles are 6 to 20 times thicker than the walls of the inner tissues. In coleoptiles, the outer wall of the outer epidermis shows a multilayered, helicoidal cellulose architecture, whereas the walls of the parenchyma and the outer wall of the inner epidermis are unilayered. In hypocotyls and epicotyls both the epidermal and some subepidermal walls are multilayered, helicoidal structures. The walls of the internal tissues (inner cortex, pith) are unilayered, with cellulose microfibrils oriented primarily transversely. Peeled inner tissues rapidly extend in water, whereas the outer cell layer(s) contract on isolation. This indicates that the peripheral walls limit elongation of the intact organ. Experiments with the pressure microprobe indicate that the entire organ can be viewed as a giant, turgid cell: the extensible inner tissues exert a pressure (turgor) on the peripheral wall(s), which bear the longitudinal wall stress of the epidermal and internal cells. Numerous studies have shown that auxin induces elongation of isolated, intact sections by loosening of the growth‐limiting peripheral cell wall(s). Likewise, the effect of light on reduction of stem elongation and cell wall extensibility in etiolated seedlings is restricted to the peripheral cell layers of the organ. The extensible inner tissues provide the driving force (turgor pressure), whereas the rigid peripheral wall(s) limit, and hence control, the rate of organ elongation.
Geosiphon pyriforme, an Endosymbiotic Consortium of a Fungus and a Cyanobacterium (Nostoc), Fixes Nitrogen
Authors: Kluge M. , Mollenhauer D. , Mollenhauer R. , Kape R. 
Published: February 2014

AbstractThe bladders of Geosiphon pyriforme, an endosymbiotic consortium of a fungus and the cyanobacterium Nostoc punctiforme, show nitrogenase activity. This suggests that the organism is capable of nitrogen fixation.
The Complex‐Heterozygotes of Oenothera grandiflora L'Her.
Authors: Schumacher E. , Steiner E. , Stubbe W. 
Published: February 2014

AbstractComplex‐heterozygotes discovered in populations of O. grandiflora in Alabama are composed of a typical grandiflora (B) complex and an altered B complex which modifies the phenotype in the direction of O. villosa (A). A cytogenetic analysis of the new complex, designated BA, is reported including results of its compatibility with different plastomes. The evidence suggests that the BA complex resulted from hybridization between O. grandiflora and the pollen complex of the sympatric O. biennis.
Temperature Dependency of Circadian Period in a Single Cell (Acetabularia)
Authors: Berger S. , Dirk J. , VON Lindern L. , Wolff D. , Mergenhagen D. 
Published: February 2014

AbstractThe circadian rhythm in the oxygen production of 30 individual Acetabularia cells has been studied at different temperatures. The temperature induced period variation was continuously evaluated over the whole data record of each individual cell with an advanced spectral analysis technique. The observed circadian periods of O2 production displayed a well established region of temperature compensation between 25 °C and 30 °C with a Q10, value of 0.9, whereas between 15°C and 22°C a positive temperature coefficient was measured (Q10 at 22 °C 0.9, Q10 at 20°C 0.8, Q10at 17°C 0.7).
Evidence for a G‐Protein Regulated Adenylate Cyclase and a Ca2/Calmodulin Controlled Phosphodiesterase in the Phytoflagellate Chlorogonium
Authors: Gromes R. , Zetsche K. 
Published: February 2014

AbstractIn the green flagellate Chlorogonium elongatum the cAMP concentration of the cells depends on the culture conditions of the alga. Autotrophically cultured cells possess three times more cAMP than cells cultured heterotrophically (in the dark with acetate).The activity of adenylate cyclase in a membrane fraction of Chlorogonium is distinctly stimulated by GTPγS. Such a stimulation is generally regarded as an indication of the participation of heterotrimeric G‐proteins in this regulatory process.The activity of phosphodiesterase is stimulated in vitro by calmodulin and inhibited by trifluoperazin and EGTA.
Immunofluorescence Study of Microtubule Organization in Some Polarized Cell Types of Selected Brown Algae
Authors: Katsaros Chr. I. 
Published: February 2014

AbstractThe microtubule (Mt) organization in apical cells of Sphacelaria rigidula. as well as in branch initials of S. rigidula and Ectocarpus siliculosus, was studied by immunofluorescence. The apical interphase cells of S. rigidula show an impressive cytoskeleton of Mts, converging on the centrosome(s). A number of Mt bundles are perinuclear, but most of them run in axial orientation from the centrosomes to the cell cortex. The anterior Mt system consists of numerous thin Mt bundles, whereas the posterior system contains fewer and thicker bundles. In cells entering prophase, the cytoplasmic Mts gradually disappear. This process is somewhat faster at the posterior than at the anterior pole of the premitotic nucleus. After mitosis, the cytoplasmic Mts of the apical region appear to be re‐organized more rapidly than those of the basal part of the cell. The apical daughter nucleus retains a lobed shape and condensed chromatin for a longer time, and increases considerably in size between telophase and cytokinesis, compared to the basal one. Duplication of the centrosomes proceeds more rapidly in the anterior region of apical cells than in the basal part. During branch formation in S. rigidula and E. siliculosus, a new polarity axis is established, and the Mts extend towards the protrusion into which the nucleus migrates before mitosis. After nuclear division, one of the daughter nuclei is positioned at the tip of the branch, where the apical Mt focussing point is localized.
Abscisic Acid and Desiccation Tolerance in Mosses
Authors: Bopp M. , Werner O. 
Published: February 2014

AbstractIn higher plants the phytohormone ABA is involved in processes that are connected to water deficit, like stomatal closure or desiccation tolerance. In bryophytes, also containing ABA in their tissues, physiological functions remained uncertain for a long time. Quite recently, several papers have shown different effects of exogenously applied ABA: stomatal closure in Anthoceros, drought hardening in Funaria and production of the landform in Riccia. In all these cases the relevant conditions (water deficit) enhance the endogenous ABA level significantly. For induced desiccation tolerance, ABA serves as a mediator to induce specific proteins (dehydrins) strongly connected with this tolerance. Therefore, it can be concluded that in bryophytes ABA has the same function as in higher plants. It acts as a mediator in stress conditions.
Cold‐induced Chromosome Regions and Karyosystematics in Sambucus and Viburnum
Authors: Benko‐Iseppon Ana Maria , Morawetz W. 
Published: February 2014

AbstractThe genera Viburnum, Sambucus and Lonicera have been investigated for chromosome number and karyomorphology including Giemsa‐C‐banding, fluorochrome (DAPI/CMA) banding and cold treatment. Cold‐induced undercontracted chromosome regions (CIRs) are found in Viburnum and Sambucus for the first time and are apparently identical with larger hc regions, shown by Giemsa C‐banding. Certain narrow C‐bands are not cold‐sensitive. CIRs frequently react brightly CMA‐positive in Viburnum and Sambucus, while DAPI fluorescence is virtually ineffective. The occurrence of CIRs within plants is possibly linked to certain nuclear characters such as large chromosomes and continuous condensation behaviour. Cold‐induction has possibly also some influence on euchromatin condensation characteristics in prophasic chromosomes.Several karyological characters point to a closer relationship between Viburnum, Sambucus and Adoxa: Relatively large chromosomes, continuous condensation behaviour, reticulate to semireticulate interphase nuclei and presence of CIRs. These genera appear isolated from Lonicera and the Caprifoliaceae s.str., which differ remarkably in karyomorphology.
Sensitive Detection of the Leaching‐out from Membrane‐surrounded Compartments: a New Approach Explored with Cells and Tissues of Nicotiana tabacum L.
Authors: Städtler Sabine 
Published: February 2014

AbstractIn search of a simple method for testing the very early events of ozone damage to susceptible plants as well as complete destruction after threshold‐exceeding treatments an over‐all measurement of cell ingredients by their optical density in the UVB and UVC range was investigated. The cell particles were liberated after membrane permeabilization or after cell bursting. Uncontrolled results could be excluded. Furthermore, the results of the developed spectrophotometrical test could be, in the case of tissue samples (leaf discs), very well reproduced with an osmometrical measurement. The latter was less sensitive and not suitable for cellular samples because the protoplasts must be dissolved in a nearly isotonic medium which caused too large a background for this method but not for the UVS test. Contrary to the osmometric measurement, the photometric one cannot be used for determining the absolute amount of cell ingredients but only for relative measurement between samples in a given range of concentrations. Oxidative changes of the liberated ingredients do not influence their detection, which was demonstrated with ascorbate. The developed leaching test was also useful for determining the membrane damage caused by the detergent Triton X‐100, although this was known to have UV absorbance by itself. It was noted that the far UV maximum is not only caused by absorbance and scattering is discussed as an additional explanation.
Plantlet Regeneration from Electrostimulated Protoplasts of Sunflower (Helianthus annuus L.)
Authors: Barth S. , Voeste D. , Wingender Ruth , Schnabl Heide 
Published: February 2014

AbstractHypocotyl protoplasts from Helianthus annuus L. were electrically stimulated using different parameters and subsequently cultivated in agarose droplets with weekly changes of the liquid media. Macroscopic visible calli (0.1‐0.3 mm) were transferred onto solid media supplemented with different concentrations of NAA, BAP, and GA3. Colonies reaching a size of about 3 mm were isolated and further cultivated under the same conditions. Several calli originating from electrically stimulated protoplasts and especially those cultured on relative high auxin concentrations, generated somatic embryos which were characterized by a green globular shoot tip and a developing root. Later on differentiation of the shoot tip occurred on kinetin‐containing MS medium leading to plantlets with stunted shoot axis. No somatic embryos were initiated in control experiments with non‐stimulated protoplasts.
Molecular Biology of Sugar Transporters in Plants
Authors: Sauer N. , Tanner W. 
Published: February 2014

AbstractBoth lower and higher plants have been shown to possess efficient transport systems for the uptake of sugars across the plasmalemma. Genes encoding transport proteins for both mono‐ and disaccharides have been cloned recently. The main cloning strategies — differential screening, complementation cloning in Saccharomyces cerevisiae, and heterologous screening — are briefly summarized. The relationship of plant sugar transporters to a superfamily of more than 50 uni‐, sym‐, and antiporters cloned so far is discussed.Various possibilities for heterologous expression (in Schizosaccharomyces pombe, Saccharomyces cerevisiae, Xenopus oocytes) of plant sugar transporters are described and compared. Eight D‐glucose transporters (from yeast to Arabidopsis to man) only possess 7% identical amino acids. First site‐directed mutations of the Chlorella HUP1 transporter indicate that at least transmembrane helices 5, 7 and 11 line the D‐glucose specific path through the membrane. The genomic structures of two plant transporters are outlined; the glycosylation of transport proteins as well as their tissue specificity is discussed.
Chasing Coiled Coils: Intermediate Filaments in Plants
Authors: Menzel D. 
Published: February 2014

AbstractThe cytoskeleton's structurally most resilient components, the intermediate filaments (IFs), have attracted the interest of cell biologists for more than two decades. IFs form extensive networks in many animal cells, and are thought to provide considerable tensile strength to the cells and tissues. In fact, the term “cytoskeleton” has originally been coined for the insoluble fibrous remains of detergent extracted animal cells. Nevertheless, cells can survive quite well without an IF network, and even without the subunit proteins that build the 10 nm wide polymeric filaments. Hence, the vital function of these cytoskeletal components is still hotly debated. Against this background, it may be premature to start suggesting functions for IFs in plants. Yet this is exactly what quite a number of researchers have begun to do. Because much recent evidence supports the idea of a plant IF cytoskeleton, it seems timely to examine this evidence and discuss its impact on our current understanding of IF function.
Characterization of Cytosolic Glutathione S‐Transferase in Spruce Needles
Authors: Schröder P. , Berkau Christiane 
Published: February 2014

AbstractActive glutathione S‐transferase (GST) has been purified from needles of Norway spruce (Picea abies L. Karst.). Two isoforms of the enzyme which exhibit different physico‐chemical and catalytic properties were separated by (NH4)2SO4 fractionation, affinity chromatography on epoxy‐activated 4% cross‐linked beaded agarose, using glutathione as the ligand, ion‐exchange chromatography, and isoelectric focusing. The isozymes have pI values of 5.5 (GST I) and 4.3 (GST II). Both GST isozymes are homodimeric proteins with subunit sizes of 26 kD (GST I), and 23 kD (GST II). The kinetic properties of the enzymes are described and compared with other plants GSTs. Only GST II is able to conjugate the pesticides fluorodifen and alachlor.