bluuebunny/crossref_metadata_2025 huggingface dataset:
The Polar Organization of the Growing Chara Rhizoid and the Transport of Statoliths are Actin‐Dependent*
Authors: Sievers A. , Kramer‐Fischer Margret , Braun M. , Buchen Brigitte
Published: February 2014

Horizontally positioned Chara rhizoids continue growth without gravitropic bending when the statoliths are removed from the apex by basipetal centrifugation. The transport of statoliths in centrifuged rhizoids is bidirectional: 50–60 % of the statoliths are re‐transported on a straight course to the apex at velocities from 1 to 14 μm . min−1 increasing towards the rhizoid tip. The centrifuged statoliths which are located closest to the nucleus are basipetally transported and caught up in the cytoplasmic streaming of the cell. Those statoliths which are located near the apical side of the nucleus are transported either apically or basally. A de‐novo‐formation of statoliths was not observed. After retransport to the apex some statoliths transiently sediment, a process which can induce a local inhibition of cell wall growth. The rhizoid bends again gravitropically only if a few statoliths finally sediment in the apex; the more statoliths that sediment in the apex the shorter the radius of bending becomes. The transport of statoliths is mediated by actin filaments which form a network of thin filaments in the apical and subapical zone of the rhizoid, and thicker parallel bundles in the basal zone where cytoplasmic streaming occurs. Both subpopulations of actin filaments overlap in the nucleus zone.
Ultrastructural Comparison of the Vacuolar and Mitochondrial H+‐ATPases of Daucus carota
Authors: Taiz Saundra Lee , Taiz L.
Published: February 2014

Eukaryotic vacuolar H+‐ATPases (V‐ATPases) are related to the F0F1‐ATPases of chloroplasts and mitochondria and are believed to be organized into peripheral and integral membrane complexes. Vacuolar membranes isolated from purified carrot (Daucus carota) root vacuoles were observed to be coated with F1‐like particles after negative staining with phosphotungstic acid. The F1‐like particles formed typical “ball and stalk” structures, about 9.4 nm in diameter and 13.6 nm in height. The head portion frequently had a characteristic bifurcation or cleft at the apex and appeared to be composed of subunits. Such “V1” complexes were frequently associated with smaller stalked particles emerging near the base. In contrast, negatively‐stained carrot mitochondrial F1 complexes averaged 8.7 nm in diameter and 11.7 nm in height. The head groups of the mitochondrial F1s were nearly always spherical, and had no other smaller structures associated with them. The V1 complexes of carrot are thus similar in form to the V1 complexes of Neurospora (Bowman et al. J. Biol. Chem. 264 (1989) 15606–15612).
Electron‐Microscopic Demonstration of a “Head and Stalk” Structure of the Leaf Vacuolar ATPase in Mesembryanthemum crystallinum L.
Authors: Klink Rebecca , Lüttge U.
Published: February 2014

The structure of the vacuolar ATPase from mesophyll tonoplasts of Mesembryanthemum crystallinum has been studied by electron microscopy using negatively stained specimens of membrane‐bound and detergent‐solubilized ATPase molecules. We observed a high density of particles on the surface of tonoplast vesicles and “head and stalk” structures on the edge of the membrane, similar to the F0F1‐ATPases of mitochondrial and chloroplast membranes. The staining conditions, which are often critical for such small objects, were improved by using methylamine tungstate as negative stain for the membrane‐bound ATPase. Compared to other staining solutions generally applied, dissociation of the F1‐like enzyme complex from the membrane was best prevented and structural damage of the vesicles was least observed with methylamine tungstate.

In freeze‐fracture electron microscopy of tonoplast vesicles, where dissociation never occurs since no detergent is used, we also observed “head and stalk” structures on the edge of the membranes, beside many particles on the fracture faces.

The detergent‐solubilized ATPase forms string‐like structures, caused by the aggregation of the hydrophobic membrane‐embedded F0‐like part of the enzyme. After negative staining the F1‐like enzyme complex is arranged alternately along both sides of the string and connected by a narrow stalk.
Photobiological and Structural Studies of Light‐driven Movements in the Solar‐tracking Leaf of Lupinus palaestinus Bioss. (Fabaceae)
Authors: Werker Ella , Shak T. , Koller D.
Published: February 2014

The compound, palmate lamina of Lupinus palaestinus reorients photonastically, as well as phototropically in response to non‐directional and directional light signals, respectively, by structural deformations of pulvini. When the excitation provided by directional light is maintained constant (fluence rate, angle of incidence and azimuth, with respect to the leaflet laminae), the entire lamina reorients towards it at a constant angular velocity over a considerable time interval and displacement.

The laminar pulvinules are considerably longer than the subtending common petiolar pulvinus and therefore contribute most to laminar reorientation. The pulvinar region is characterized by transverse folds around its circumference, and longitudinal rib‐like thickenings on the external walls of its epidermis that facilitate axial and transverse deformations. Specialized “joints”, at the distal and proximal ends of each pulvinule, contribute most to its flexing. Anthocyanin is notable by its absence. Specialized “motor” tissues surrounding the central vascular core participate in pulvinar deformation by undergoing directional and differential volume changes. The bundle sheath is characterized by numerous starch grains. The multi‐layered cortical parenchyma exhibits an abundance of transversely oriented primary pit fields and associated plasmodesmata. When the leaflet lamina rotates around its midrib, the pulvinus twists along its axis, exhibiting epidermal and cortical deformation. The functional significance of these specializations is discussed.
Mechanisms of Reduction of the Stelar Pattern along Barley Roots
Authors: Luxová Mária
Published: February 2014

The stelar pattern along the seminal and nodal roots of barley (Hordeum vulgare L.) is gradually simplified due to a decreasing frequency of longitudinal cell division in the apical meristem. The decrease involves the proportion of stelar parenchyma, the number of vascular strands on the periphery of the stele and, in nodal roots with a more complex structure, the number of central metaxylem files. In spite of the fact that the stelar parenchyma is reduced in distal parts of the roots to approximately one half, the discontinuity of central and peripheral metaxylem is preserved. Reduction of the number of central metaxylem files is due to fusion. In the reduction of peripheral xylem and phloem strands, the development of certain xylem strands is discontinued and they are terminated blindly. Two phloem strands that had alternated radially with them, approach each other, coalesce and a single phloem strand continues to develop. In this way the regular alternation of phloem and xylem is re‐established. The importance of fusions ensuring reduction of the functional continuity in vascular tissue by formation of a network structure must be stressed. This reduction mechanism is involved not only in files of the wide central metaxylem but also in phloem strands which are thus preferred over blindly terminating peripheral xylem strands.
Thermoluminescence and Delayed Luminescence Investigation of the Green Alga, Chlamydobotrys stellata
Authors: Wiessner W. , Mende D. , Deak Z. , Demeter S.
Published: February 2014

Thermoluminescence 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

It 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

Plasma 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

Cell 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

Biochemical 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

The 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

The 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

The 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

The 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

Complex‐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

The 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

In 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

The 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

In 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

The 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

In 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

Hypocotyl 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

Both 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

The 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

Active 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.
Touch‐ and Methyl Jasmonate‐induced Lignification in Tendrils of Bryonia dioica Jacq.
Authors: Kaiser Isolde , Engelberth J. , Groth Beate , Weiler E. W.
Published: February 2014

The touch‐induced free coiling response of Bryonia dioica tendrils is accompanied by the differentiation of supporting tissue at the ventral side of the organ, becoming the inner (concave) side of the coiled tendril. As part of this process, the Bianconi plate, a continuous sclerenchyma sheath stretching along the ventral face of the five bicollateral vascular bundles, becomes strongly lignified. During this reaction, the extractable activity of phenylalanine ammonia‐lyase in the tendrils increases four‐ to five‐fold, while the amount of PAL, as demonstrated by immunoblotting, remains unchanged. This touch‐induced process can also be elicited by airborne application of methyl jasmonate. The PAL inhibitor, 2‐aminoindan‐2‐phosphonic acid (AIP) completely inhibits both the touch‐ and methyl jasmonate‐induced deposition of lignin‐like material in the Bianconi plate, but has no effect on coiling. From these results, it can be concluded that the cessation of growth at the ventral side of a free‐coiling tendril is not due to induced lignification but rather, lignification seems to serve the function of increasing the mechanical strength of the coiled tendril.
Geosiphon pyriforme, an Endosymbiotic Association of Fungus and Cyanobacteria: the Spore Structure Resembles that of Arbuscular Mycorrhizal (AM) Fungi
Authors: Schüßler A. , Mollenhauer D. , Schnepf E. , Kluge M.
Published: February 2014

The zygomycete Geosiphon pyriforme is the only known endocyanosis of a fungus. The Nostoc spp. filaments are included in photosynthetically active and nitrogen fixing, multinucleated bladders, which grow on the soil surface. The spores of the fungus are white or slightly brownish. They are about 250 μm in diameter and develop singly on hyphal ends or, less frequently, intercalarly. The wall of the spores consists of a thin innermost layer, a laminated inner layer with a thickness of about 10–13 μm, and an evanescent outer layer. The laminated layer is composed of helicoidally arranged microfibrils, and is separated from the evanescent outer layer by a thin electron‐dense sublayer. Polarisation microscopy indicates the occurrence of chitin. Shape and wall ultrastructure of the Geosiphon spores and their cytoplasm resemble that of Glomus spores, but are different from that of other genera of the Glomales and Endogonales. Germination occurs by a single thick hyphal outgrowth directly through the spore wall. Like various AM forming fungi, Geosiphon pyriforme contains endocytic bacteria‐like organisms, which are not surrounded by a host membrane. Our observations indicate that Geosiphon is a potential AM fungus.
Imaging the K, Mg, Na and Ca Distributions in Flax Seeds using SIMS Microscopy
Authors: Jauneau A. , Ripoll C. , Verdus Marie‐Claire , Lefebvre F. , Demarty M. , Thellier M.
Published: February 2014

Taking advantage of the sensitivity, the lateral resolution and the ability of secondary ion mass spectrometry (SIMS) for elemental imaging, we have shown that the main alkaline and alkaline‐earth cations exhibited clear‐cut regionalization in flax seeds. Calcium, and even more magnesium were almost exclusively located within the protein bodies (PBs); and they were practically absent from the tissue areas with no PBs, such as the provascular tissue. By contrast, sodium was almost exclusively located outside the PBs; moreover, most of the seed sodium was in the tissues at the seed periphery (chiefly the teguments). Among the studied cations, potassium was the only one with a non‐negligible concentration both in and outside the PBs.
Blue, Green and Red Fluorescence Signatures and Images of Tobacco Leaves*
Authors: Lang M. , Lichtenthaler H. K. , Sowinska Malgorzata , Summ P. , Heisel Francine
Published: February 2014

Laser‐induced fluorescence images of the leaf of an aurea mutant of Nicotiana tabacum were recorded for the blue and green fluorescence at 440 and 520 nm and the red chlorophyll fluorescence at 690 and 735 nm. The results obtained were compared with direct measurements of the fluorescence emission spectra of leaves using a conventional spectrofluorometer. The highest emission of blue (F440) and green fluorescence (F520) within the leaf was found in the leaf veins, particularly the main leaf vein. In contrast, the intercostal fields of leaves, which exhibited the highest chlorophyll content, showed only a very low blue and green fluorescence emission, which was much lower than the red and far‐red chlorophyll fluorescence emission bands (F690 and F735). Correspondingly, the ratio of blue to red leaf fluorescence F440/F690 of upper and lower leaf side was much higher in the leaf veins (values 1.2 to 1.5) than in intercostal fields (values of 0.6 to 0.7). The results also demonstrated that in the intercostal fields the major part of the blue‐green fluorescence was reabsorbed by chlorophylls and carotenoids. A partial reabsorption of the red fluorescence band near 690 nm by leaf chlorophyll took place, but did not affect the far‐red fluorescence band near F735. As a consequence the chlorophyll fluorescence ratio F690/F735 exhibited significantly higher values in the chlorophyll‐poor leaf vein regions (1.7 to 1.8) than in the chlorophyll‐rich intercostal fields (0.8 to 1.3). Imaging spectroscopy of leaves was shown to be much more precise than the screening of fluorescence signatures by conventional fluorometers. It clearly demonstrated that the blue‐green fluorescence and the red chlorophyll fluorescence of leaves exhibit an inverse contrast to each other. The advantage of the fluorescence imaging spectroscopy, which allows the simultaneous screening of the whole leaf surface and distinct parts of it, and its possible application in the detection of stress effects or local damage by insects and pathogens, is discussed.
Compartmentation of Zinc in Roots and Leaves of the Zinc Hyperaccumulator Thlaspi caerulescens J & C Presl
Authors: Vázquez M. D. , Poschenrieder Ch. , Barceló J. , Baker A. J. M. , Hatton P. , Cope G. H.
Published: February 2014

Thlaspi caerulescens is a metallophyte that is able to hyperaccumulate Zn. In the present study the subcellular compartmentation of Zn was investigated in roots and leaves of this species by means of X‐ray microanalysis.

Leaves accumulated higher average Zn concentrations than roots. In roots of plants exposed to 10 μM Zn, Zn concentrations in the apoplast were similar to those in vacuoles, while in plants treated with 100 μM Zn considerably higher Zn concentrations were detected in vacuoles than in the apoplast. In epidermal and sub‐epidermal cells of leaves of plants from both treatments, Zn mainly accumulated in vacuoles and, to a lesser extent, in the apoplast. In vacuoles from plants exposed to 100 μM Zn, high Zn concentrations were associated with variable amounts of P, Ca and K. In leaves, the highest Zn concentrations (13,600 μg g−1 d.m.) were found in globular crystals present in many vacuoles of epidermal and subepidermal cells. Smaller deposits with a variable Zn concentration between 1,000 and 18,300 μg g−1 d.m. were observed in the epidermal and subepidermal cells of roots. Both the high Zn/P element ratios found in the crystals and the absence of Mg indicate that, in contrast to other plant species, myo‐inositol hexaphosphate (phytate) is not the main storage form for Zn in Thlaspi caerulescens.
Fish Poisoning Plants in Africa
Authors: Neuwinger H. D.
Published: February 2014

Fishing with the aid of plant toxins was formerly very common in tropical Africa. Today this easy method of fishing is still practised in remote areas. The method is simple: the poisonous ingredients are pounded and thrown into a pool or dammed‐up sections of a small river. After a short time the fish begin to rise to the surface and can then readily be taken by hand. The fish can be eaten without health problems. The main active compounds are saponins, rotenoids and diterpene esters. Such biologically active plants are of great interest to scientists of various disciplines. Some of these plants provide important insecticides, many play an important part in traditional medicine and in preparation or arrow poisons.

258 fish‐poisoning plants are presented, based on 25 years of field research by the author in tropical Africa and evaluations of herbarium notes. 10–20 per cent of the fishing poisons are probably still unknown. They are spread among 167 plant genera and 60 families. The evaluation shows a clear dominance of the Leguminosae (Caesalpiniaceae, Mimosaceae, Papilionaceae) in the hierarchy of the fish poisoning plants. It is also remarkable that a great proportion are in the Euphorbiaceae.
Elicitation of 2,3‐Dihydroxybenzoic Acid and Ajmalicine in a Catharanthus roseus Suspension Culture*
Authors: Frankmann K. T. , Kauss H.
Published: February 2014

Addition of an elicitor preparation from cell walls of Phytophthora megasperma f. sp. glycinea (Pmg elicitor) to a newly established cell suspension culture of Catharanthus roseus induced extracellular free 2,3‐dihydroxybenzoic acid, suggesting its role in pathogen defense. The same substance also accumulated intracellularly in a bound form. Treatment of the crude Pmg elicitor preparation with trypsin abolished elicitor activity, suggesting that the active fraction is proteinaceous. The cells became more sensitive to low but not to elevated elicitor concentrations when they were pretreated with 2,6‐dichloroisonicotinic (DCIA) or 5‐chlorosalicylic (5CSA) acid for about 1 day before addition of the elicitor. This indicates that the elicitor reception/transduction system becomes improved by these compounds known to be related to systemic acquired resistance against plant pathogens. The newly established cell line initially accumulated also the indole alkaloid ajmalicine, a process enhanced by Pmg elicitor. This potency was lost during subculturing for about 1 year and was also not restored by preincubation with DCIA or 5CSA. In contrast, elicitation of 2,3‐dihydroxybenzoic acid synthesis was undiminished, suggesting that the Pmg elicitor perception system was still functioning and not the cause for the decline in elicited indole alkaloid production.
Intracellular Localization of Jasmonate‐Induced Proteins in Barley Leaves
Authors: Hause Bettina , zur Nieden Uta , Lehmann J. , Wasternack C. , Parthier B.
Published: February 2014

The plant growth substance jasmonic acid and its methyl ester (JA‐Me) induce a set of proteins (jasmonate‐induced proteins, JIPs) when applied to leaf segments of barley (Hordeum vulgare L. cv. Salome). Most of these JIPs could be localized within different cell compartments by using a combination of biochemical and histochemical methods. Isolation and purification of various cell organelles of barley mesophyll cells, the separation of their proteins by one‐dimensional polyacrylamide gel electrophoresis and the identification of the major abundant JIPs by Western blot analysis, as well as the immuno‐gold labelling of JIPs in ultrathin sections were performed to localize JIPs intracellularly. JIP‐23 was found to be in vacuoles, peroxisomes, and in the granular parts of the nucleus as well as within the cytoplasm; JIP‐37 was detected in vacuoles and in the nucleoplasm; JIP‐66 is a cytosolic protein. Some less abundant JIPs were also localized within different cell compartments: JIP‐100 was found within the stromal fraction of chloroplasts; JIP‐70 is present in the peroxisome and the nucleus; JIP‐50 and JIP‐6 accumulate in vacuoles. The location of JIP‐66 and JIP‐6 confirms their possible physiological role deduced from molecular analysis of their cDNA.
How to Evolve a Complex Plastid? ‐ A Hypothesis
Authors: Häuber M. M. , Müller S. B. , Speth V. , Maier U.‐G.
Published: February 2014

The evolution of complex plastids in general and the phylogeny of the intermediate forms present in chlorarachniophytes and cryptophytes are considered. By comparing possible protein transport mechanisms in these algae, also taking into account problems in explaining horizontal gene transfer between eukaryotic nuclei, we arrive at the hypothesis that the initial step in the evolution of complex plastids was a primary endocytobiosis of the host (!) cell. Our hypothesis also explains why the nucleomorph (the reduced nucleus of a secondary endocytobiont) is not eliminated.
Coloured Pollen in Cactaceae: a Mimetic Adaptation to Hummingbird‐Pollination?
Authors: Rose Marie‐Jeanette , Barthlott W.
Published: February 2014

Pollen of 361 species from 71 genera of Cactaceae was investigated for this study of the correlation between pollen colour and the pollination syndrome. 11% of all species studied had red or brown pollen, and nearly all of these species were ornithophilous. This suggests that pollen colour probably is part of the bird‐flower syndrome of Cactaceae. Possibly the red or brown pollen might be a crypto‐mimetic adaptation to the dark coloured bill of the pollinating hummingbird (Trochilidae) and secures safe transport to a receptive stigma without being removed by the bird immediately.

The results are discussed against a background of studies encompassing about 900 species from 77 families, which provide further evidence for the proposed adaptive significance of palynological characters.
Specific Transport of Inorganic Phosphate and C3‐ and C6‐Sugar‐Phosphates across the Envelope Membranes of Tomato (Lycopersicon esculentum) Leaf‐Chloroplasts, Tomato Fruit‐Chloroplasts and Fruit‐Chromoplasts
Authors: Schünemann Danja , Borchert Sieglinde
Published: February 2014

Plastidial envelope membranes were isolated from tomato (Lycopersicon esculentum) leaves and green and red tomato fruits by isopycnic discontinuous sucrose density gradient centrifugation. Solubilized envelope membrane proteins were reconstituted into liposomes. Transport measurements revealed that the phosphate translocator from tomato leaves transports inorganic phosphate, 3‐phosphoglycerate and triosephosphates. The phosphate translocators of green and red fruit plastids catalyze, in addition to the transport of these substrates, also the transport of glucose‐6‐phosphate, glucose‐1‐phosphate and phosphoenolpyruvate.
Tissue‐ and Cell‐Specific Distribution of Connexin 32‐and Connexin 26‐related Proteins from Vicia faba L.
Authors: Janßen Martina , Hunte Carola , Leineweber Kirsten , Knop Mona , Cramer H. , Traub O. , Schulz Margot
Published: February 2014

Different tissues (leaf lamina and midveins, epidermis, primary roots, etiolated shoots, hypocotyl, petioles) and protoplasts from mesophyll, guard cells, and petioles of Vicia faba L., obtained from defined developmental stages were analyzed with polyclonal antibodies raised against mouse liver connexins 26 and 32. Immunostaining after treatment with CX 26 antibodies showed two polypeptides of 21 and 16 kD in all tissues examined except for hypocotyl and epidermis. Additionally, a stronger immunoresponse at 40 kD occurred in extracts from leaf material, mesophyll protoplasts, and roots.

Incubation with the CX 32 antibodies resulted in an immunoreactive band at 29 kD in mesophyll protoplast samples, and, a very weak band in extracts from leaf material. A 36 kD polypeptide, present in samples prepared from root, etiolated shoots, petioles, and midveins, did not appear in leaf laminas and mesophyll protoplasts. Extracts from guard cells did not show any immunoreactive band. The tissue‐ and cell‐specific distribution of CX 23‐ and CX 26‐related proteins is supposed to reflect diversities in physiological functions together with alterations in plasmodesmatal ultrastructures during development.
Blue Light Reception in Phycomyces: Red Light Sensitization in madC Mutants
Authors: Galland P. , Amon S. , Senger H. , Russo V. E. A.
Published: February 2014

Sporangiophores of the zygomycete fungus Phycomyces blakesleeanus are sensitive to near UV and blue light. The quantum effectiveness of yellow and red light is more than 6 orders of magnitude below that of near UV or blue light. Phototropism mutants with a defect in the gene madC are about 106 times less sensitive to blue light than the wild type. These mutants respond, however, to yellow and red light when the long wavelength light is given simultaneously with actinic blue light. In the presence of yellow or red light the photogravitropic threshold of madC mutants is lowered about 100‐fold though the yellow and the red light alone are phototropically ineffective. A step‐up of the fluence rate of broad‐band red light (> 600 nm) from 6 × 10−3 to 6W m−2 elicits, in mutant C 148 madC, a transient deceleration of the growth rate. The growth rate of the wild type is not affected by the same treatment. The results are interpreted in terms of a red light absorbing intermediate of the blue light photoreceptor of Phycomyces. The intermediate should be short‐lived in the wild type and should accumulate in madC mutants.