bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of the Molecular Organization of Photosystem I During Light‐Dependent Chloroplast Differentiation in Mutant C‐6D of Scenedesmus obliquus*
Authors: Römer S. , Humbeck K. , Senger H. 
Published: February 2014

AbstractCells of pigment mutant C‐6D of the green alga Scenedesmus obliquus synthesize only Chl a and precursors of carotenoids during heterotrophic growth in the dark. These cells exhibit high PSI‐activity per Chl and a low Chl/P700‐ratio. After transfer to light, Chl a, Chl b and carotenoids are formed with different kinetics.Analysis of chlorophyll fluorescence emission and excitation spectra revealed a sevenfold increase in the amount of the long wavelength antenna of PSI (720 nm) resulting in an increase in the absorption cross section of PSI during illumination. The underlying changes in molecular organization of PSI were investigated by sucrose density centrifugation of solubilized thylakoids after digitonin treatment and subsequent identification of the components by gel electrophoresis, HPLC and fluorescence. In dark grown cells one blue‐green band (0‐II) could be resolved. This band contained only Chl a and the reaction center complex of PSI, CPI.After 24 hours of illumination three pigmented zones and a small amount of free pigment were observed. One of the zones (24‐I) was identified as a light‐harvesting fraction containing the pigment‐protein complexes LHCP1 and LHCP3. In the second fraction (24‐II) the reaction center complexes of PSI and PSII were found. The highest molecular weight fraction (24‐III) was enriched in PSI‐complexes of higher molecular weight and contained a high amount of long wavelength fluorescence antenna (720 nm) attributed to PSI. In contrast to band 24‐II which contained a high percentage of β‐carotene and a high Chl a/b‐ratio, the Chl a/b‐ratio of fraction 24‐III was lower and the xanthophyll content increased.Our data demonstrate an increase in the PSI‐unit size during chloroplast development in mutant C‐6D of Scenedesmus obliquus. Dark‐grown cultures have small functional PSI‐units composed of the chlorophylls involved in charge separation and the core antenna. This unit contains only Chl a and no carotenoids. After transfer to light Chl b and carotenoids are formed. Simultaneously with the appearance of carotenoids and Chl b, PSI‐complexes of higher molecular weight are synthesized indicating the addition of a LHC to the reaction center complex of PSI.
PPiase‐Activated ATP‐Dependent H+ Transport at the Tonoplast of Mesophyll Cells of the CAM Plant Kalanchoë daigremontiana*
Authors: Marquardt‐Jarczyk Gisela , Lüttge U. 
Published: February 2014

AbstractThe co‐ordinated action of the two proton‐transporting enzymes at the tonoplast of the CAM plants. daigremontiana, viz. the ATPase and the PPiase, was studied by measuring fluorescent dye quenching. The initial rates of ATP and PPi‐dependent H+ transport into tonoplast vesicles were additive, i.e. the sum of the rates obtained with each substrate alone was in the range obtained with both substrates added together at the same time. Conversely, the activities of the two H+ pumps were non‐additive in establishing the steady‐state level, indicating that the final steady state was under thermodynamic control of a maximal attainable proton gradient. The initial rates of ATP‐dependent H+ transport were stimulated enormously if ATP was added a few minutes after pre‐energization of the vesicles with PPi. This stimulation was observed only when the PPiase was active. A similar effect was not found for PPi‐dependent H+ transport after pre‐energization with ATP. Hence, a PPiase‐activated ATP‐dependent H+ transport can be distinguished from the basic ATP‐ and the basic PPi‐dependent H+ transport. In parallel a PPi‐dependent stimulation of ATP hydrolysis in the absence of ionophores was measured, which can only be attributed to the activity of the PPiase. PPiase‐activated ATP‐dependent H+ transport depends on the presence of permeant anions. It shows properties of both H+ transport activities, i.e. the chloride and malate stimulation and the DCCD inhibition of the ATP‐dependent H+ transport activity, the nitrate stimulation and the KF inhibition of the PPi‐dependent H+ transport activity. Only MgPPi and MgATP were effective as the respective substrates. The PPiase‐activated ATP‐dependent H+ transport had a half life of about 5–9 minutes. It is concluded that the PPiase may play an important role in kinetic regulation of the ATPase, and implications for CAM metabolism are discussed.
Potential Consequences of Virus Infection for Shade‐Sun Acclimation in Leaves
Authors: Osmond C. B. , Berry J. A. , Balachandran S. , Büchen‐Osmond C. , Daley P. F. , Hodgson R. A. J. 
Published: February 2014

AbstractAttention is drawn to literature evidence that leaf virus infection may interfere with synthesis of ribulose‐1,5‐bisphosphate carboxylase oxygenase, and with the activity of photosystem II, two main requirements for shade‐sun acclimation. Preliminary experiments which show that virus infections resulting in these interactions can lead to photosynthetic physiology diagnostic of nitrogen limited plants and/or shade ecotypes are presented. Other observations on the diversity of virus infections in sun populations of wild species commonly found in the shade are presented. Together, this evidence leads to the hypothesis that virus infection may well confine individuals of some species to shaded habitats because infection prevents acclimation to bright light, and predisposes them to photoinhibition.
The Compatibility of d‐Pinitol and 1d‐1‐O‐Methyl‐Muco‐Inositol with Malate Dehydrogenase Activity
Authors: Sommer Christiane , Thonke Barbara , Popp Marianne 
Published: February 2014

AbstractPinitol (1d‐3‐O‐methyl‐chiro‐inositol) and 1d‐1‐O‐methyl‐muco‐inositol, two cyclitols wide‐spread in the plant kingdom, were isolated from plant sources in order to test their compatibility with malate dehydrogenase activity. Both compounds had no inhibitory effect on malate dehydrogenase from Rhizophora mangle in a range of 100 to 1000 mol . m−3.Their influence on malate dehydrogenase activity from different plant sources (Rh. mangle L., Mesembryanthemum crystallinum L., Cicer arietinum L. and Spinacia oleracea L.) was also small and similar to that observed for a number of well established compatible solutes (e.g. proline, glycine betaine). A possible role of cyclitols as cryoprotectants or radical scavengers is discussed.
Isoenzyme Variation in Asian Beans
Authors: Jaaska Velio , Jaaska Vilve 
Published: February 2014

AbstractElectrophoretic variation of isoenzyme characters encoded by 20 gene loci has been studied in 9 species of Asian beans, comprising subgenus Ceratotropis of the genus Vigna. Four species of hypogeal germination type, V. angularis, V. umbellata, V. dalzelliana and V. minima, are shown to form a distinct monophyletic group in the subgenus, sharing common electromorphs of two major isoenzymes of aspartate aminotransferase. V. glabrescens is confirmed to be an allotetraploid derivate of two diploids closely related to V. radiata and V. umbellata, but divergent from their contemporary accessions analyzed. V. trilobata is the most variable species of the subgenus in isoenzyme characters. It reveals intraspecific differentiation at several isoenzyme loci correlated with the seed morphology and geographical localization.
Primary Phloem Development in the Shoot Apex of Rhizophora mangle L. (Rhizophoraceae)
Authors: Behnke H.‐D. , Richter K. 
Published: February 2014

AbstractThe primary phloem in the shoot apex of the mangrove Rhizophora mangle L. is largely confined to the comparatively condensed area between the first three leaf pairs. The main extension zone, surrounded by the stipular sheath of the third leaf pair, contains vascular bundles arranged in a procambial ring and characterized by a well‐developed primary phloem and a less advanced xylem. The phloem consists of a great number of sieve elements, an equal number of associated companion cells, and a few phloem‐parenchyma cells.The differentiation of the sieve‐element protoplast (with e.g., chromatolytic nuclear degeneration, loss of the vacuole and most organelles) proceeds largely according to a well‐known pattern. Their P‐type plastids, however, form their protein crystals rather late and therefore cannot be used as an early cell marker. Lateral sieve‐element walls are distinct from other wall parts and walls of other cells by their heavy nacreous thickenings, the formation of which is shown to be strictly correlated with the occurrence and orderly arrangement of cortical microtubules.
Antibiotics, Sugars, and Amino Acids in Nectar of Rhododendron and Piptanthus Species from Nepal
Authors: Martini M. , Schmid Angela , Hess D. 
Published: February 2014

AbstractNectars were extracted in Helambu and Langtang Nepal Himalayas from Rhododendron arboreum and Rh. barbatum (Ericaceae), and from Piptanthus nepalensis (Fabaceae), and analyzed for sugars, amino acids, and antibiotic activity. Sugar content in Rhododendron nectar varied from 17 to 65%. In most nectars, G and F were present in a 1:1 ratio. In addition, from a Rh. arboreum nectar, S could be detected. Piptanthus nectar showed a very high sugar content (up to 80%), F and G, or F, G, and S, respectively, being the main sugar constituents. In all Rhododendron nectar amino acids could be found. In Piptanthus nectar there were no traceable amino acids. Neither an evolutionary significance of amino acid contents in floral nectar nor their close correlation with bees, the main pollinators of both genera, could be confirmed from our studies. Rhododendron nectar showed antibiotic activity due to the presence of acetylandromedol. The biological significance of acetylandromedol, the main toxic principle from Rhododendron nectar, seems to be its antibiotic activity, which could possibly compensate for lower sugar contents in preventing bacterial growth.
Tetrathiafulvalene Radical Cation — A New Potent Inhibitor of Anion Transport in a Green Alga
Authors: Rybová Renata , Nešpůrková L. , Ryba O. , Janáček K. 
Published: February 2014

AbstractAn inhibitory effect of potassium ferricyanide on the light‐dependent active uptake of chloride anions into the alga Hydrodictyon reticulatum has drawn attention to the possibility that chloride transport proceeds as an exchange for electrons and hence can be impaired by artificial electron acceptors. Tetrathiafulvalene radical cation present in solutions of the highly conductive TTF‐C1 crystals is easily reduced to TTF0 and inhibits the chloride uptake more powerfully than does ferricyanide. A practically complete inhibition of Cl− uptake is brought about by 3 × 10−5 M TTF+. The presence of ferricyanide actually reduces the inhibitory effect of TTF+; the complex equilibria of a mixture of the two electron acceptors were examined by cyclic voltammetry and a competition between the two for the inhibitory function has been suggested as a possible explanation.
Assimilate Partitioning in the Variegated Coleus Leaf
Authors: Plomann Martina , Eschrich W. 
Published: February 2014

AbstractMature leaves of a variegated cultivar of Coleus blumei Benth. with a green border and central albino region constitute a source‐sink system suitable for studies on assimilate partitioning. Leaves treated with 14CO2 on a small part of the intact green border export assimilate via the shortest path into the stem. Leaves with all but a small lobe of the green border removed show different partitioning of labeled assimilates when the leaf is exposed to 14CO2 (Fisher and Eschrich, 1985): The whole albino region of the leaf is supplied but no tracer is exported into the stem. When the green border is completely removed, 14CO2‐treatment of the albino region leads to the fixation of CO2, obviously by PEP carboxylase, as indicated by the occurrence of labeled malate. Results show that the albino region of the variegated leaf constitutes a potential sink when deprived of its green border. In addition, CO2‐fixation by PEP carboxylase in albino tissue seems to indicate a common capacity of leaves which is normally masked by photosynthesis. The difference of assimilate partitioning between leaves with intact and leaves with partly removed green borders demonstrates that the unlabeled assimilates control the movement of labeled assimilates.
Nickel‐hyperaccumulating Plants Provide a Niche for Nickel‐resistant Bacteria
Authors: Schlegel H. G. , Cosson J.‐P. , Baker A. J. M. 
Published: February 2014

AbstractThe occurrence and abundance of nickel‐resistant bacteria was studied in various soils originating from serpentine and other ultramafic rocks from both temperate and tropical localities. Samples were taken from soil covered with herbs and shrubs not known to accumulate nickel and from areas inhabited by nickel‐hyperaccumulating shrubs and trees. In samples taken from the humus and mineral soil layers underneath the canopy of nickel‐hyperaccumulating trees, the number of bacteria able to grow at 3, 10 and 20 mM NiCl2, was almost as high as the number of bacteria growing in the absence of nickel ions. In contrast, for soil samples taken outside these areas only moderately nickel‐resistant (3 mM NiCl2) bacteria and low numbers were encountered. It is concluded that, in humid climate zones, the predominance of nickel‐resistant bacteria in the soil is not due to the nickel ions generated by the weathering of nickel‐containing rocks but is due to nickel salts being continuously liberated by the decay of nickel‐rich leaf litter. Nickel‐hyperaccumulating plants can be considered to drive a nickel cycle resulting in the continuous percolation of the top soil by nickel ions.
Agrobacterium‐Mediated Transfer of the GUS Gene into Pollen of Petunia
Authors: Süssmuth Jutta , Dressier K. , Hess D. 
Published: February 2014

AbstractTransfer of the GUS gene into pollen has been studied in co‐cultures of Agrobacterium and Petunia pollen. The Agrobacterium strain used contains a GUS gene between the two borders of the T‐DNA. Uptake and integration of this GUS gene could be shown using two different restriction systems. First, by appropriate cleavage within the T‐DNA the GUS gene could be isolated intact from Agrobacterium‐treated pollen. Second, using enzymes with cleave the T‐DNA only once, integration of this T‐DNA into individual pollen genomes could be shown. The fragments obtained could not be obtained from Agrobacterium alone. The positive Southern blots were reprobed with vir probes, but all were negative. Also following plating, no Agrobacteria could be detected from our pollen DNA preparations. Therefore, the signals obtained were not due to contaminating bacteria. Due to a high endogenous GUS activity of Petunia pollen the expression of the transferred gene could not be studied. The data demonstrate the uptake and integration of T‐DNA into pollen and are closing a gap in the line of evidence for the functioning of an indirect Agrobacterium — mediated gene transfer. Besides this, it should be stressed that only this indirect pollen system leads to success.
The Symplechosome: a Unique Cell Organelle of some Basidiomycetes*
Authors: Bauer R. , Oberwinkler F. 
Published: February 2014

AbstractAn unusual cell organelle of some basidiomycetes, the symplechosome, is described and illustrated in detail using Saccoblastia farinacea as an example. Symplechosomes are structurally similar, but not identical to “classical” dictyosomes of green plants and animals. As is typical for dictyosomes, each symplechosome consists of a stack of platelike cisternae. The central portions of the symplechosome‐cisternae are flattened, and adjacent cisternae are separated in the mid‐region by an intercisternal space of constant width. In contrast to dictyosomes, the intracisternal spaces are completely obliterated in the central area, and hexagonally arranged bars extend between adjacent cisternae. Identical bars often connect the symplechosomes with mitochondria. Symplechosomes are highly complex‐structured organelles which differ significantly from the simple individual Golgi cisternae or “Golgi bodies” observed in asco‐ and basidiomycetes.
Filament Disruption in Funaria Protonemata: Occlusion of Plasmodesmata
Authors: Schnepf E. , Sawidis Th. 
Published: February 2014

AbstractPlasmodesmata are occluded when Funaria chloronemata are fragmented by the development of tmema cells (TCs). The TC deposits a new wall layer along the cross wall toward the neighbouring non‐sister cell (NC). This wall layer cuts off the plasmodesmata and its connection with the cross wall is soon lost. The plasmodesmata become isolated when the NC forms a new wall layer along the former cross wall. At the end of TC development, before its disintegration, the sister cell (SC) also deposits a new wall layer along the cross wall toward the TC, cutting off the plasmodesmata. For some time the plasmalemma of the plasmodesmata remains connected to the NC or the TC, whereas the desmotubule soon disappears. Relicts of the plasmalemma remain even after the isolation of the plasmodesmata and the disintegration of the TC. During the decay of the plasmodesmata, a cylinder of electron‐dense material is frequently formed along the border of the plasmodesmatal channel. This may extend over the surface of the cell wall. Eventually, the plasmodesmatal channel is filled with wall material. Callose is only observed around functional plasmodesmata and does not seem to play a role in their occlusion.
Adaptation of the Photosynthetic Apparatus of Chlorella and Ankistrodesmus to Blue and Red Light
Authors: Senge M. , Senger H. 
Published: February 2014

AbstractThe mode of adaptation of the photosynthetic apparatus of three unicellular green algae, Ankistrodesmus braunii, Chlorella fusca and Chlorella saccharophila to red and blue light are documented by the fluence‐rate curves of photosynthetic oxygen evolution. For all three algae tested photosynthetic capacity, respiration and light compensation point were higher for cells grown under red light, while the chlorophyll content increased in blue light‐grown cells. Blue light‐adapted cells have a lower chlorophyll a to chlorophyll b ratio and more chlorophyll in the light‐harvesting system than red light‐adapted cells, as shown in the electrophoretic profile of the pigment‐protein complexes. It is concluded that the action of red light resembles that of high levels of white light, while blue light causes the same effects as low levels of white light. In agreement with previous publications these findings indicate that the mode of adaptation to different light qualities is ubiquitous in unicellular green algae.
Circannual Growth Rhythm in a Brown Alga, Pterygophora californica
Authors: Lüning K. 
Published: February 2014

AbstractA circannual rhythm was found in the kelp Pterygophora californica which forms a new blade with a free running period of 7 − 8 months under constant conditions. Individual plants exposed to cycles of daylength with T = 12, 6, or 3 months performed 1, 2, or 4 growth cycles, respectively, in one calendar year showing the entrainment of the endogenous circannual rhythm. The annual growth cycle also followed a phase shift of the annual cycle of daylength (T = 12 months) by 3 or 6 months.
Responses of Dictyostelium discoideum to Multiple Environmental Stimuli
Authors: Häder D.‐P. , Hansel A. 
Published: February 2014

AbstractThe movement responses of the cellular slime mold Dictyostelium discoideum to multiple stimuli were investigated. The responses were found to differ depending on the developmental stage of the organism. A novel response, positive gravitaxis, was found in Dictyostelium slugs but not in amoebae. In the presence of a simultaneous light stimulus, gravitaxis is effective only at low fluence rates. Slugs showed positive thermotaxis in a thermal gradient (0.2 °C cm−1) and ignored the simultaneous light stimulus at low fluence rates (< 10−3 W m−2), while at higher fluence rates they moved toward the light source. With a combination of a thermal gradient and gravity Dictyostelium slugs clearly oriented thermotactically ignoring the gravistimulus.
Transient Gene Expression in Sunflower Mesophyll Protoplasts
Authors: Kirches E. , Frey N. , Schnabl Heide 
Published: February 2014

AbstractExperiments on transient gene expression were performed with mesophyll protoplasts isolated from young leaves of the sunflower (Helianthus annuus L.). Both PEG‐mediated DNA transfer as well as electroporation, were shown to be suitable for the introduction of a foreign gene. The expression of the reporter gene β‐glucuronidase was measured by a fluorimetric GUS assay. Inhibiting RNA synthesis by cordycepine (3‐deoxyadenosine) or translation of mRNA by cycloheximide suggests that biologically active plasmid‐DNA as well as functional mRNA transcripts are available for only short time periods in transfected protoplasts. Electroporation was carried out using rather high pulses in the microsecond range. Results indicate, that DNA uptake is more efficient using PEG, while electroporation causes less damage in DNA treated mesophyll protoplasts.
Non‐light‐dependent Shikimate Pathway in Plastids from Pea Roots
Authors: Leuschner Carola , Schultz G. 
Published: February 2014

AbstractNon‐green plastids (leucoplasts) isolated from pea roots are shown to be considerably active in forming aromatic amino acids by the shikimate pathway which, in contrast to the chloroplast pathway, is independent of light. Supply of phosphoenolpyruvate and 3‐dehydroquinate, 3‐dehydroshikimate, shikimate and quinate effectively enhances the formation of aromatic amino acids suggesting an intra‐ or/and intercellular intermediate transport.
Hypervariable DNA Fingerprint Loci in Microseris pygmaea (Asteraceae, Lactuceae)
Authors: van Houten W. H. J. , van Heusden A. W. , Voort J. Rouppe v. d. , Raijmann L. , Bachmann K. 
Published: February 2014

AbstractOligo‐GATA containing probes reveal DNA fingerprinting patterns in DNA of Microseris pygmaea after restriction enzyme digestion. There are only a few major restriction fragments. These are longer than 2 kb, and they differ completely among plants from different populations, among most members of a single local inbreeding population, and even among some parent and offspring plants. In the F2 of an interpopulation hybrid, major fingerprint bands could be assigned to 2 unlinked loci by 3: 1 and 1: 2: 1 segregations respectively, one further band segregated roughly 1: 1, one band appeared irregularly. The hypervariability of the GATA‐fingerprint loci contrasts with a low variability of other genetic markers in M. pygmaea and with a more complex but less variable GATA‐fingerprint pattern in related species.
Vacuolar Lucifer Yellow Uptake in Plants: Endocytosis or Anion Transport; A Critical Opinion
Authors: Robinson D. G. , Hedrich R. 
Published: February 2014

AbstractBecause of its membrane‐impermeant‐properties Lucifer Yellow‐CH (LY) is regarded by animal cell biologists as an ideal tracer for fluid‐phase endocytosis. When presented to plant cells or protoplasts this fluoroprobe accumulates in the vacuole. On the other hand there are many cases where LY does not enter the vacuole when loaded into the plant cytosol. These, superficially divergent, results have previously been explained in terms of endocytosis whereby access to the vacuole is considered to occur through vesicle transport. This interpretation has now been challenged in three recent papers where the benzoic acid derivative, probenecid, has been shown to prevent vacuolar LY accumulation in plants. Since probenecid is a well‐known inhibitor of organic anion transport in animal cells it has been argued that anion carriers capable of transporting LY might also exist at the plasma membrane and tonoplast of plant cells. Unfortunately probenecid has rarely, if ever, been used in plant transport studies. The fact that it is a weak acid, whose inhibitory effects are observed at concentrations of around 1 mM suggests that caution should prevail when interpreting results obtained with probenecid. The purpose of this article is therefore to highlight the current controversy surrounding LY uptake by plants and to critically evaluate the recent probenecid data.