bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hydroxycinnamic Acid Transferases in the Biosynthesis of Acylated Betacyanins: Purification and Characterization from Cell Cultures of Chenopodium rubrum and Occurrence in Some Other Members of the Caryophyllales*
Authors: Bokern Maria , Heuer Susanne , Strack D. 
Published: February 2014

AbstractAn acyltransferase from cell cultures of Chenopodium rubrum was purified 515‐fold with a 2.5 % recovery. This enzyme catalyzes the transfer of hydroxycinnamic acids from 1–0‐hydroxycinnamoyl‐/β‐glucose to the C‐2 hydroxy group of glucuronic acid of amaranthin (betanidin 5‐O‐glucuronosylglucose). The invivo products formed are celosianin I (4‐coumaroylama‐ranthin) and celosianin II (feruloylamaranthin). The enzyme can be classified as l‐0‐hydroxycinnamoyl‐β‐glucose: amaranthin O‐hydroxycinnamoyl‐transferase (EC 2.3.1.‐). Its molecular weight was determined by gel filtration column chromatography to be ca. 69.5 kDa. Maximal rate of product formation was found to be at pH 5.6. The isoelectric point of the enzyme was at pH 4.7. The reaction temperature maximum was at 37 °C and the apparent energy of activation was calculated to be 44.5kJ mor−1. The enzyme showed a Vmax of 910pkat (mg protein)−1 with amaranthin as acceptor and feruloylglucose as acyl donor. The ratios of Vmax/Km values for sinapoyl‐, feruloyl, caffeoyl‐ and 4‐coumaroylglucoses were found to be 100:56:56:40. Donor competition experiments support the conclusion that one single enzyme is responsible for the ester formation with the different hydroxycinnamic acids. From the possible acceptors tested, only amaranthin (15S configuration) and isoamaranthin (15R) were esterified with Km values of 280 and 800 μM, respectively. Catalytic effectivity (Vmix/Km) was found at a relative ratio 15S:15R of 100:42. Betanin (betanidin 5‐O‐glucoside) and gomphrenin I (betanidin 6‐O‐glucoside) were not accepted. Some other acylated betacyanin‐containing members of four families of the Caryophyllales were investigated and showed the same type of hydroxycinnamoyltransferase activity with 1‐O‐hydroxycinnamoylglucose as acyl donor, but with different acceptor molecule specificities.
γ‐Glutamylcysteinylserine — A New Homologue of Glutathione in Plants of the Family Poaceae*
Authors: Klapheck S. , Chrost B. , Starke J. , Zimmermann H. 
Published: February 2014

AbstractIn addition to glutathione (γ‐GluCysGly), many species of the family Poaceae have another tripeptide which has the amino acid sequence γ‐GluCysSer. This thiol was isolated from etiolated leaves of wheat (Triticum aestivum L. cv. Star). Its structure was elucidated by quantitative amino acid analysis after total hydrolysis and by partial hydrolysis with carboxypeptidase A and γ‐glutamyltranspeptidase. The content of γ‐GluCysSer in the leaves of T. aestivum is increased by incubation with sulfate and is severely diminished by incubation with buthionine sulfoximine, a specific inhibitor of γ‐glutamylcysteine synthetase. Oxidized γ‐GluCysSer is reduced by yeast glutathione reductase with a rate somewhat lower than for glutathione, but the new tripeptide is not a substrate of glutathione‐S‐transferase from equine liver.Besides homoglutathione (γ‐GluCysßAla), a tripeptide found in plants of the order Fabales, the tripeptide γ‐GluCysSer is the second homologue of glutathione detected in plants.
Enzymatic Characteristics of UDP‐sulfoquinovose: Diacylglycerol Sulfoquinovosyltransferase from Chloroplast Envelopes*
Authors: Seifert U. , Heinz E. 
Published: February 2014

AbstractEnvelope membranes from chloroplasts contain UDP‐sulfoquinovose: diacylglycerol sulfoquinovosyltransferase which catalyses the final step in sulfolipid assembly. In situ produced diacylglycerol served as radioactive acceptor to measure enzymatic activity. With this assay, several enzymatic parameters were investigated. The enzyme, which has maximal activity at pH 7.5, was stimulated by magnesium ions due to a decrease of the Km for uridine 5′‐diphospho‐sulfoquinovose from 80 pM (no magnesium) to 10 μM (5 mM magnesium). This stimulation had a Km of 0.7 mM magnesium and may be relevant in light/dark modulation of the enzymatic activity. The lower efficiency of guanosine 5′‐diphospho‐sulfoquinovose observed before can be ascribed to a higher Km of this sugar nucleotide (400 μM). Under optimized and linearized conditions the sulfoquinovosyltransferase displayed about 10% of the activity of the UDP‐galactose: diacylglycerol galactosyltransferase which competes in the same membrane system for diacylglycerols. Addition of acidic lipids, such as sulfolipid and phosphatidylglycerol, to envelope membranes resulted in an inhibition of the sulfoquinovosyltransferase, whereas the galactosyltransferase was not affected. In vivo this may contribute to an adjustment of the sulfolipid proportion in plastid membranes. In contrast to the galactosyltransferase the sulfoquinovosyltransferase did not discriminate against the dipalmitoyl molecular species of diacylglycerol when offered together with the oleoyl‐palmitoyl species. Under conditions when oleoyl‐palmitoyl‐and dipalmitoyl‐diacylglycerols were synthesized with concurrent conversion to monogalactosyl and sulfoquinovosyl diacylglycerol, the sulfolipid was highly enriched in the fully saturated species. This may explain the occurrence of dipalmitoyl species in sulfolipids, as found in many plants.
Enzymatic Pathways for the Consumption of Carbonyl Sulphide (COS) by Higher Plants*
Authors: Protoschill‐Krebs G. , Kesselmeier J. 
Published: February 2014

AbstractCarbonyl sulphide (COS) is an important trace gas of the atmosphere. Considerable uncertainties remain concerning the global sinks of COS. Vegetation is believed to be an unqualified sink in the global cycle of COS. We investigated whether there is an enzymological background for the consumption of COS by higher plants in analogy to CO2. Photometric measurements demonstrated that all enzymes involved in C02 assimilation by higher plants can also metabolise COS. The key enzyme for COS metabolism in higher plants is carbonic anhydrase, an enzyme which probably directly splits COS into C02 and H2S. Such a pathway would explain the observed deposition of COS to vegetation.
Transport Processes in Vacuoles of Higher Plants
Authors: Martinoia E. 
Published: February 2014

AbstractThe vacuole is the largest compartment of a mature plant cell and serves as an internal reservoir of metabolites and nutrients. In the last years transport of solutes across the tonoplast has been intensively investigated. It was shown that two different proton pumps reside in the tonoplast. These pumps generate an electrochemical gradient which can be used as an energy‐source to accumulate solutes. Cation uptake is driven by an H+ antiport mechanism. Anions are accumulated in response to the inside positive membrane potential. In addition, the existence of ion channels was shown using the patch clamp technique. The aim of this review is to compare and to discuss the present state of our knowledge of solute transport across the tonoplast.
K+ and Cl− Conductance of Arabidopsis thaliana Plasma Membrane at Depolarized Voltages
Authors: Cerana Raffaella , Colombo Roberta 
Published: February 2014

AbstractThe ion currents, activated by depolarizations, across the plasma membrane of Arabidopsis thaliana cultured cells were studied by means of the patch‐clamp technique in the whole‐cell configuration. The electrical conductance of the membrane could be shifted from a cation to an anion conducting state by changes in the [K+]: [Cl−] ratio in the external medium. For ratios between 1:1 and 1:5 the currents were due to K+ efflux and for a ratio of 1:10 to Cl− influx. In the cation conducting state the permeability ratio of K+ over NH+4 and the alkali metal ions was: K+ ≅ NH>Na+ ≅ Li+ >Cs+. In the anion conducting state the permeability of NO−3 was the same as that of Cl−. These channels were activated by depolarizations in the range of physiological potentials (‐70/‐80mV) and, either by mediating the efflux of cations or the influx of anions, they could function to re‐hyperpolarize the membrane potential after depolarizations due to the influx of cations or of solutes cotransported with protons and/or to the inhibition of electrogenic pumps.
Nectar Secretion Pattern and Removal Effects in Six Argentinean Pitcairnioideae (Bromeliaceae)
Authors: Galetto L. , Bernardello L. 
Published: February 2014

AbstractNectar secretion pattern and effects of nectar removal were analyzed in six hummingbird‐pollinated Argentinean Pitcairnioideae: Abromeitiella brevifolia. A. lorentziana, Deuterocohnia longipetala. Dyckia floribunda, D. ragonesei and Puya spathacea. Flower lifetime was determined in each case. Nectar volume, concentration and sugar production were measured from bud opening till fading of flowers at different time intervals according to the species' flower life‐span. Nectar volume varies while nectar concentration and cumulative sugar production increase as a function of flower age in all the studied species. In general, total nectar volume and concentration values can be affected by periodic removal, but total sugar production is unaffected. Only in Puya spathacea did periodic nectar harvesting reduce the total amount of sugar produced.
Lipophilic Phenolics from the Leaves of Empetrum nigrum — Chemical Structures and Exudate Localization
Authors: Wollenweber E. , Dörr M. , Stelzer R. , Arriaga‐Giner F. J. 
Published: February 2014

AbstractIn the course of continuing studies on the occurrence and chemical composition of lipophilic exudates on plant surfaces, the leaves of Empetrum nigrum have been studied. They were found to produce a considerable amount of lipophilic material which mostly consists of phenolic compounds. We here report the identification of two dioxygenated chalcones, three dioxygenated dihydrochalcones, and two dihydrophenanthrene derivatives. Exept for one chalcone, all these compounds were found for the first time as natural products.The upper and lower epidermis of the rolled hypostomatous leaves bear glandular trichomes. By flavonoid specific staining it can be shown that these natural products are accumulated within the capitate glandular cells.
Effects of Exogenously Supplied Ammonium on Root Development of Scots Pine (Pinus sylvestris L.) Seedlings
Authors: Vollbrecht P. , Kasemir Helga I. 
Published: February 2014

AbstractThe effect of potentially toxic concentrations of ammonium on root development of Scots pine seedlings raised on Perlite was investigated during growth periods of 3 or 10 weeks after sowing. It was shown that imbalanced ammonium nutrition led to conspicuous changes of root morphology provided the pH value in the medium was allowed to decrease to 3.9 due to the NH+4‐dependent proton excretion into the rhizosphere. Ammonium toxicity could not be observed with seedlings treated either with ammonium nitrate or with ammonium chloride at pH 5.3 − 6.8. While the supply of NH+4 considerably inhibited root development the biomass production of the shoot was increased. Determination of the endogenous level of ammonium in roots and the leaf whorl exclude a simple causal correlation between ammonium toxicity and accumulated ammonium as has been postulated for herbaceous plants.
Selection of Microspore Derived Embryogenic Structures in Maize Related to Transformation Potential by Microinjection
Authors: Gaillard A. , Matthys‐Rochon E. , Dumas C. 
Published: February 2014

AbstractMicrospores are attractive targets for transformation of maize through DNA microinjection since they may allow, through the development of embryogenic structures, the regeneration of transgenic plants without chimerism. Unfortunately, microinjection into unicellular microspores is technically difficult because of the presence of the exine. However, in later stages of development, this difficulty may be overcome. In this regard, our objective was to determine the most suitable stages of early androgenic development for microinjection using lucifer yellow as a marker dye. Experiments have shown that the fluorescent dye is able to spread inside the whole embryogenic structure (about 4–10 days old), only in those cases where internal cell walls are still absent or incompletely formed, as assessed by cytological observations. At later stages, when the septation is completed and the embryo is cellularized, diffusion of the dye is no longer possible. These results demonstrate that multinuclear structures with the broken exine and a cytoplasm not yet partitioned, may be conveniently used for direct transformation via microinjection.
Towards a Revision of the Systematics of the Genus Chlamydomonas (Chlorophyta)
Authors: Ettl H. , Schlösser U. G. 
Published: February 2014

AbstractStrains of Chlamydomonas with cross‐reacting sporangium wall autolysins also correspond in morphology, reproduction, development, and physiological properties. We therefore undertook a revision of the systematics of the genus based on this correlation. Isolates of Chlamydomonas available in culture collections were re‐examined microscopically, preferably with respect to their reproduction and development. In particular all authentic clones, on which earlier species diagnoses had been founded, were included. Their detectable autolysins were tested crosswise in bioassays. We intend to complete and extend species diagnoses in order to separate species more precisely. ‐ At first 7 strains with a common sporangium autolysin have been examined, four of which are the authentic cultures of the species C. aggregate Deason et Bold, C. akinetos Deason et Bold, C. applanata Pringsheim, and C. humicola Lucksch. They have been brought together under the name of the species first described, C. applanata Pringsheim, due to their apparent similarities in morphology and development. An amended species diagnosis is presented. The significance of authentic cultures as important sources of further information is discussed.
Leaf Surface Microflora May Significantly Affect Studies on Foliar Uptake of Chemicals
Authors: Schreiber L. , Schönherr J. 
Published: February 2014

AbstractUptake and desorption kinetics of methylglucose and pentachlorophenol (PCP) by needles of Picea abies (L.) Karst. were studied. Uptake of methylglucose was very rapid, equilibrium was obtained within 2 h and the amounts of methylglucose associated with the needles could be completely desorbed within 8 h. In contrast, PCP uptake was steady for several hours and the amounts of PCP taken up could only partially be desorbed again. Needles treated with NaN3 prior to uptake measurements, showed no methylglucose uptake at all, whereas PCP uptake was not affected. Thus it is concluded that the hydrophilic methylglucose was taken up solely by epiphytic microorganisms, whereas the lipophilic PCP was taken up into the needle interior in significant amounts. Consequences of these results on studies of foliar uptake of chemicals are pointed out.
Bafilomycin Inhibits Vacuolar pH Regulation in a Fresh Water Charophyte, Chora corallina
Authors: Okazaki Y. , Tazawa M. , Moriyama Y. , Iwasaki N. 
Published: February 2014

AbstractBafilomycin A1, known as an inhibitor of vacuolar type H+‐ATPase, was used to study involvement of the vacuolar ATP‐dependent H+‐pump in the vacuolar pH regulation in a fresh water charophyte, Chara corallina. When bafilomycin A1 (100 nM) was externally given to intact cells, the vacuolar pH (about 5) was not affected. Internodal cells were then pretreated with 100 nM bafilomycin for 1 − 2 h and the vacuolar sap was replaced with a weakly buffered solution of pH 7.4. The readjustment of the modified vacuolar pH in bafilomycin‐treated cells was significantly retarded compared with that in untreated cells.Next, bafilomycin A1 was directly introduced into the vacuole by vacuolar perfusion with the artificial cell sap of pH 7.4. At 100 nM bafilomycin A1, the decrease in the vacuolar pH was significantly inhibited. When cell sap was replaced with the artificial cell sap containing no buffer (pH 5.2 − 5.5), the vacuolar pH increased in the presence of vacuolar bafilomycin, suggesting that the PP1‐ dependent H+ pumping alone was not sufficient for the pH regulation of Chara vacuoles.Intracellular bafilomycin A1 had no effect on the plasma membrane potential of tonoplast‐free cells, which is evidence that it does not affect the electrogenic H+‐pump in the plasma membrane. Bafilomycin A1 inhibited the ATP‐dependent H+ transport of tonoplast vesicles but not the PP1‐dependent H+ transport. The ATPase activity of tonoplast vesicles was also inhibited by bafilomycin A1.
Apoplastic Transport through the Fungal Sheath of Pinus sylvestris/Suillus bovinus Ectomycorrhizae
Authors: Behrmann P. , Heyser W. 
Published: February 2014

AbstractRoots of Pinus sylvestris L. were inoculated in vitro with the basidiomycete Suillus bovinus (Fr.) O. Kuntze. To investigate apoplastic transport in mycorrhizal and sterile roots of Pinus sylvestris, roots of intact plants were submerged for 20 h in 0.1% solutions of the fluorescent dye sulphorhodamine G (SR‐G) or for 6 h in 1.5% solutions of lanthanum nitrate. Samples treated with the dye were cryofixed, freeze‐dried or freeze‐substituted and embedded into Spurr's medium, maintaining strictly anhydrous conditions to prevent movement of the water‐soluble dye after cryofixation. Lanthanum‐treated roots were fixed in glutaraldehyde, post‐fixed in OsO4, dehydrated in a graded acetone series and embedded in Spurr's resin. The apoplastic distribution of the two tracers were examined either using fluorescence optics (sulphorhodamine) or with the electron microscope (La3+).The yellow‐green fluorescence of sulphorhodamine could be detected within the apoplast of the fungal sheath, the Hartig net and the host cortex, up to the endodermis. Electron‐dense lanthanum deposits were located in the fungal sheath, the Hartig net and in the root cortex. Greater deposition was detected within the matrix material, in which the hyphae of the mantle are embedded. The apoplastic distribution of the two tracers within the plant root did not indicate any significant qualitative differences between sterile and mycorrhizal rootlets. In contrast to reports by other authors, we conclude that the fungal sheath does provide an apoplastic pathway for water and ions at least in Pinus sylvestris/Suillus bovinus mycorrhizae. However, the mobility of charged molecules, particularly cations, may be limited by the fungal matrix.
Investigations of the Blue‐green Fluorescence Emission of Plant Leaves
Authors: Lang M. , Siffel P. , Braunová Zuzana , Lichtenthaler H. K. 
Published: February 2014

AbstractThe UV light (337 nm) induced blue‐green fluorescence emission of green leaves is characterized at room temperature (298 K) by a maximum near 450 nm (blue region) and a shoulder near 525 nm (green region) and was here also studied at 77 K. At liquid nitrogen temperature (77 K) the blue (F450) and green fluorescence (F525) are much enhanced as is the red chlorophyll fluorescence near 735 nm. During development of green tobacco leaves the blue fluorescence F450 (77 K) is shifted towards longer wavelengths from about 410 nm to 450 nm. The isolated leaf epidermis of tobacco showed only slight fluorescence emission with a maximum near 410 nm. The green fluorescence F525 was found to mainly originate from the mesophyll of the leaf, its intensity increased when the epidermis was removed. The red chlorophyll fluorescence emission was also enhanced when the epidermis was stripped off; this considerably changed the blue/red fluorescence ratios F450/F690 and F450/F735. The epidermis, with its cell wall and UV‐light‐absorbing substances in its vacuole, plays the role of a barrier for the exciting UV‐light. In contrast to intact and homogenized leaves, isolated intact chloroplasts and thylakoid membranes did not exhibit a blue‐green fluorescence emission.
Altered Pterin Patterns in Photoreceptor Mutants of Phycomyces blakesleeanus with Defective madl Gene
Authors: Hohl N. , Galland P. , Senger H. , Eslava A. P. 
Published: February 2014

AbstractAction spectra of photogravitropic equilibrium were measured for the wild type of the lower fungus Phycomyces blakesleeanus and three photobehavioral mutants with defects in the madl gene. The action spectrum for the wild type NRRL1555 had major peaks at 383 and near 460 nm and subsidiary peaks at 365 and 422 nm. The action spectra of the mutants, L1 49 mad1712, L151 mad1714 and L153 mad1716 differed significantly from that of the wild type. One prominent feature of the three mutants was hat the near‐UV peaks at 365 and 383 nm, which were not well resolved in the wild type, were of approximately equal height in the mutants and were separated by an extremely sharp valley at 378 nm. The steepness of this valley suggests interaction of multiple receptors. The second prominent feature of the mutants was their enhanced 422 nm peak. The gross changes of the photogravitropic action spectra associated with the madl genotype indicate that the respective gene product acts early in the photosensory transduction chain, very likely at the level of a complex photoreceptor system. Flavins and pterins, two pigment classes which were expected to function as chromophores of the near‐UV/blue light photoreceptor system, were analyzed for stage I sporangiophores of the wild‐type and the mutant strains by HPLC with fluorescence detection. In the wild‐type strain NRRL1555, and also in the three madl mutants, flavins were found to be present at the following concentrations: riboflavin (2.9 × 10−6 M), FMN (3.8 × 10−6M) and FAD (1.3 × 10−6 M). No significant effect of the madl mutations on the flavin content could be discerned. Among the pterins found in the wild type and the madl mutants were biopterin, 6,7‐dimethylpterin, neopterin, pterin and xanthopterin. These pterins occurred in all strains in the micromolar range and none of them was significantly reduced in the mutants. However, biopterin, 6,7‐dimethylpterin and xanthopterin occurred in some excess in one of the madl mutants. The most significant feature of the madl mutants was that they had almost completely lost one unidentified pterin with a retention time of 18 − 20 min. Another two unidentified pterins were reduced about twofold in the mutants compared to the wild type. The results suggest an involvement of pterins in the photoreception of near‐UV and blue light in Phycomyces.
Lichenizing Rhizomorphs and Thallus Development in the Squamulose Lichen Aspicilia crespiana Rico ined. (Lecanorales, Ascomycetes)
Authors: Sanders W. B. , Rico V. J. 
Published: February 2014

AbstractThis work describes the rhizomorphs and their relation to thallus development in the squamulose lichen Aspicilia crespiana Rico ined. The rhizomorphs capture algal cells, giving rise to new squamules terminally or laterally. The thallus thus consists of a network of lichenized squamules interlinked by mycobiontic rhizomorphs. A previously proposed comparison of lichen rhizomorphs to the prothallus (hypothallus) of crustose lichens is applied and expanded upon. Other less organized prothallic structures sometimes produced by A. crespiana are also described. The importance of lichenizing rhizomorphs as an essential feature of thallus growth in this species is emphasized and a competitive role in substrate occupation and thallus expansion is suggested.