bluuebunny/crossref_metadata_2025_split huggingface dataset:
Molecular Aspects of Herbicide Action on Protoporphyrinogen Oxidase
Authors: Nicolaus Beate , Sandmann Gerhard , Böger Peter 
Published: August 2018

Abstract
Protoporphyrinogen oxidase, the last enzyme of the common tetrapyrrole biosynthetic pathway, is inhibited by several peroxidizing compounds resulting in accumulation of photodynamic tetrapyrroles, mainly protoporphyrin IX. The inhibition characteristics of two chemi­cally unrelated compounds were studied using membrane bound protoporphyrinogen oxidase from corn etioplasts. As shown by Lineweaver-Burk-analysis, the inhibition of enzyme activity by the diphenyl ether oxyfluorfen and the cyclic imide MCI 15 are competitive with respect to the substrate. The competitive interaction of protoporphyrinogen and the two chemically un­related inhibitors indicate a relative specificity of the binding site. The reversibility of oxyfluorfen inhibition was evaluated by dilution experiments and was shown to be independent of the presence of DTT. The analysis of structure-activity-relationship on protoporphyrinogen oxidase inhibition was investigated with para-substituted derivatives of phenyl-3,4,5,6-tetrahydro-phthalimides. The results obtained by QSAR -calculation yielded a good correlation of the inhibitory activity determined by the lipophilicity of the para-substituent. These data point to one binding region of the inhibitors within a lipophilic environment associated with the active center of the enzyme.
New Peroxidizing Herbicides: Activity Compared with X-Ray Structure
Authors: Kohno Hitoshi , Hirai Kenji , Hori Masahiro , Sato Yukiharu , Böger Peter , Wakabayashi Ko 
Published: August 2018

The crystal structure of 3-(4-chloro-5-cyclopentyloxy-2-fluorophenyl)-5-isopropylideneoxazolidine- 2,4-dione (BW -4), chlorophthalim and oxyfluorfen were determined by X -ray analysis. The molecular size of these compounds was almost the same, but the angle between the oxazolidine and the phenyl ring (BW -4), the imide and phenyl ring (chlorophthalim ) and between the two phenyl rings (oxyfluorfen) differed.
The phytotoxic activities, determined by growth inhibition of Scenedesmus cells, loss of chlorophyll, and peroxidative destruction of photosynthetic pigments, were different among these compounds. The angle and length of BW-3, BW-4 and oxyfluorfen showing best phytotoxic activity were found approximately 65 -95 ° and 11 - 13 Å, respectively. These preliminary findings indicate that both angle and length of the molecule have some bearing on peroxidative activity.
3 α-Hydroxysteroid-5β-oxidoreductase in Tissue Cultures of Digitalis lanata
Authors: Stuhlemmer Ursel , Haussmann Werner , Milek Frank , Kreis Wolfgang , Reinhard Ernst 
Published: August 2018

Abstract
Putative intermediates of cardenolide biosynthesis, namely progesterone, pregnenolone, 5β-pregnane-3,20-dione or 5β-pregnan-3β-ol-20-one, were administered to light- or darkgrown shoot cultures of Digitalis lanata. The unsaturated com pounds were reduced to their respective 5 a-pregnanes, 5β-pregnane-3,20-dione was reduced to 5β-pregnan-3α-ol-20-one and 5β-pregnan-3β-ol-20-one was isomerized to the respective 3α-pregnane.
Suspension cultures of Digitalis lanata, on the other hand, accumulated both the 3α- and the 3β-isom er of 5β-pregnan-3-ol-20-one when incubated in the presence of 5β-pregnane- 3.20-dione. When 5β-pregnan-3α-ol-20-one was administered the cultured cells accumulated large amounts of the 3β-isomer together with small amounts of 5β-pregnane-3,20-dione, which may be regarded as an intermediate during the isomerization reaction.
Cell-free, buffered extracts from light-grown shoots were shown to reduce 5β-pregnane- 3.20-dione almost exclusively to 5β-pregnan-3α-ol-20-one when 0.05 m MgCl2 were present in the incubation mixture. Under these conditions the formation of 5β-pregnan-3β-ol-20-one was inhibited. The enzyme activity could be recovered from m em brane-free supernatants. Optimum enzyme activity occurred at pH 7.0 and 42 °C. The energy of activation was 56.2 kJ/mol and the enzyme reaction was found to be NADPH -dependent. SH reagents were essential for enzyme activity. The enzyme seems to be specific for 5β-pregnan-3-ones since neither 5 a-pregnane-3-ones nor Δ4/Δ5-pregnenes were reduced.
The NADPH : 5β-pregnane 3α-hydroxysteroid-5β-oxidoreductase described here may play a role in the regulation of cardenolide biosynthesis by removing precursors, such as 5β-pregnane-3,20-dione, from the pathway
Effect of Different Condensed Tannins on Trichoplusia ni Performance
Authors: González-Coloma Azucena , Wisdom Charles S. , Rundel Philip W. 
Published: August 2018

Abstract
To examine the assumption that condensed tannins exhibit uniform activity against herbivores, tannins extracted from four plant species with different in vitro protein binding abilities were fed to larvae of Trichoplusia ni in artificial diets. Larvae were measured for survivorship, growth and food consumption at three tannin concentrations (0.001%, 0.01% and 0.05% w. wt.). Larval performance was negatively affected by the tannins tested in a dose-response fashion, giving the different plant-derived tannins different activity thresholds. We did not find any significant correlation between the biological effects of these tannins and their protein binding abilities. This study indicates that different species of tannins do not act uniformly against a tannin sensitive herbivore, and that these differences can not be attributed to their different in vitro protein binding abilities
Study of Canadian Propolis by GC-MS and HPLC
Authors: García-Viguera C. , Ferreres F. , Tomás-Barberán F. A. 
Published: August 2018

Abstract
Propolis and propolis balsam from Canada was analyzed by gas chromatography-mass spectrometry and high performance liquid chromatography and the results compared. The compounds identified indicated that the main plant source was Populus from Section Aigeiros
Evidence for Nickel in the Soluble Hydrogenase from the Unicellular Green Alga Scenedesmus obliquus
Authors: Zinn Thomas , Schnackenberg Jörg , Haak Dieter , Römer Susanne , Schulz Rüdiger , Senger Horst 
Published: August 2018

Cultures of the green alga Scenedesmus obliquus were grown in the presence of either the chelating reagent EDTA or NiCl2 in various concentrations and assayed for hydrogenase catalyzed photohydrogen evolution after an anaerobic dark adaptation period. Cultivation of algae in the presence of 100 μm EDTA inhibited the formation of hydrogenase activity by 37%. After a cultivation of the cells in the presence of 5-20 μm NiCl2 photohydrogen evolution was increased by 20-40% . Addition of EDTA up to a final concentration of 1.5 mᴍ had no effect on the activity of hydrogenase in cell-free hydrogenase preparations.
Cultures grown in the presence of radioactive 63NiCl2 incorporated 63Ni in a parallel fashion to the cell growth. In radioactive labeled hydrogenase preparations a co-elution of radioactivity and hydrogenase activity could be observed using gel filtration chromatography.
Pheromones 98* Olfactory Electroantennogram Responses of the Formicine Ants Lasius niger and Formica Species (Hymenoptera: Formicidae) to 3,4-Dihydroisocoumarins
Authors: Kern Friedrich , Bestmann Hans Jürgen 
Published: August 2018

Electroantennogram (EAG) studies of the formicine genera Lasius and Formica (Hymenoptera, Formicidae) were carried out with 3,4-dihydroisocoumarins, recently identified as trail pheromones within this ant subfamily. The here investigated formicine species Lasius
niger, Formica rufa, F. fusca and F. sanguinea were all responsive towards stimuli of synthetic 3,4-dihydroisocoumarins. Synthesized samples of natural 3,4-dihydroisocoumarins, found in the hindgut of these species evoke the highest electrophysiological responses while structure analogues were less efficient. Number and position of the methyl groups of test substances were important factors for structure activity in EAG. F. fusca and L. niger showed a stereoisomeric differentiation in EAG responses between (R)- and (S)-isomers of 8-hydroxy-3,5,7- trimethyldihydroisocoumarin, a component in the hindgut of both species. Higher electrophysiological activity for (R)-8-hydroxy-3,5,7-trimethyl-3,4-dihydroisocoumarin in comparison to the (S)-isomer agrees with better behavior responses of previous trail following tests in the case of Lasius niger.
The Oligomeric Arrangement of the Light-Harvesting Chlorophyll a/6-Protein Complex of Photosystem II
Authors: Jackowski Grzegorz , Kluck Ewa 
Published: August 2018

Abstract
The light-harvesting chlorophyll a/b-protein complex of photosystem II (LHC II) was isolated from carnation (Dianthus caryophyllus L.) leaves by K+-induced aggregation of n-hep-tylthioglucoside-treated photosystem II particles. When solubilized with a mixture of lithium docedyl sulphate, octyl-β-D-glucopyranoside and dodecyl-β-D-maltoside the LHC II was re­ solved by mild sodium dodecyl sulphate-polyacrylamide gel electrophoresis into four oligo­meric forms and a monomeric one. LHC II contained five major polypeptides only two of which (27 and 26 kDa) were found to be its authentic components. The oligomeric forms of LHC II were found to differ in the stoichiometric ratios of the polypeptides present. The 26 kD a polypeptide was enriched in the largest oligomeric forms while the 27 kDa polypep­tide tended to form a monomer or to assemble as lower oligomeric states of LHC II.
Hypothesis on the Control of D 1 Protein Turnover by Nuclear Coded Proteins in Chlamydomonas reinhardtii
Authors: Bracht E. , Trebst A. 
Published: August 2018

A hypothesis is presented on the events in the degradation of the D 1 protein of photosys­tem II in the light. It proposes the existence of a nuclear encoded cleavage system that is turning over and which is modulated by its phosphorylation state. A new experimental approach is presented in which the D 1 protein degradation under photoinhibitory light is tested in Chlamydomonas reinhardtii grown under phosphate deficiency and pretreated with cyclo-heximide.
Under these conditions the degradation of the D 1 protein is delayed whereas in Chlamydomonas reinhardtii grown in full medium the D 1 protein is rapidly disappearing in high light upon addition of chloramphenicol (CAP) or lincomycin for inhibiting the resynthesis of the D 1 protein . Cycloheximide (CHI) has little effect on photoinhibition in such control cells. In cells grown, however, for 20 h in phosphate deficiency - such that there is not yet loss of photosynthesis capacity -pretreatment with cycloheximide or canavanine in low light the degradation of the D 1 protein even in 6 h high light is prevented to an appreciable extent. Further addition of CAP or lincomycin has only a small effect. [14C]leucine incorporation was used to show that there is no resynthesis and that the presence of the D 1 protein is due to a delay of degradation.
The results are interpreted to show that excess high light which converts the D 1 protein into a potentially, degradable mode is not sufficient for degradation of the D 1 protein. A cleavage system is needed as well. It is postulated that under phosphate deficiency and pre-treatment with CHI or canavanine a nuclear coded cleavage system for the D 1 protein is depleted, i.e. the cleavage system for the rapidly turning over D 1 is also turning over.
It is shown that under phosphate deficiency an alkaline phosphatase activity in the chloroplast and the thylakoid membrane of Chlamydomonas reinhardtii is increased. It is proposed that the ratio of kinase/phosphatase converts an active, stable phosphorylated cleavage system into a labile unphosphorylated and turning over state
Oxyfunctionalization of α-and β-Pinene by Selected Basidiomycetes
Authors: Busmann Dagmar 
Published: August 2018

Abstract
Several strains of basidiom ycetes were examined for their ability to transform α-and β-pinene in agitated submerged cultures. Four major metabolites of α-pinene (verbenol, verbenone, myrtenol, and trans-pinocarveol) and three main metabolites of β-pinene (1,4-cineol, myrtenol, and trans-pinocarveol) were isolated from the fermentation broth. The metabolic pathways included allylic oxidation, oxidative cleavage and further regioselective oxidation. Ganoderma applanatum was found to carry out the stereoselective allylic hydroxylation of α-pinene to verbenol, and of β-pinene to trans-pinocarveol in trans position to the C -C bridge. The optimal conditions of the bioreaction were established with respect to substrate concentration, incubation time and conversion time. Due to growth inhibition caused by elevated substrate concentration, the bioconversion of β-pinene required pre-grown cultures. Generally, mycelial pellet cultures were supplemented with the terpene substrate when a residual glucose content of 50% was reached. Depending on strain this point was reached after about 48 h. An incubation period of two to three days gave best yields. The transient accumulation of oxygenated products apparently reflected different reaction velocities of the successive catabolic steps.
End-of-Day Light Control of Growth and Pigmentation in the Red Alga Porphyra umbilicalis (L.) Kützing
Authors: Figueroa F. L. , Aguilera J. , Niell F. X. 
Published: August 2018

Abstract
The effects of end-of-day light pulses on thallus expansion, cell size, pigmentation and intracellular accumulation of C and N in the red alga Porphyra umbilicalis were analysed. Red (R) light pulses applied at the end of 12 h white light photoperiod for 14 d stimulated thallus expansion and produced an increase in cell size. Growth rate was higher after red (R) than after blue (B) light pulses. Red or blue light affect thallus expansion, but not the thallus weight, and was partially reversed by far-red (FR) light pulses.
Red light pulses promoted chlorophyll a accumulation whereas B light pulses stimulated the accumulation of phycoerythrin, phycocyanin and soluble protein. The effects of R or B light pulses on pigmentation were partially reversed by FR light, except for phycocyanin. Intracellular C content was similar under both R and B light treatments and higher than after FR light pulses and non-irradiated control. However, intracellular N content was higher after end-of-day R than after end-of-day B light pulses. Total absorptance (400-760 nm) of the thalli was higher after B than R light pulses. However, the ratio of total absorptance and concentration of total pigments (chlorophyll and biliproteins), used as index of light absorp­ tion efficiency, was higher after R than after end-of-day B light pulses. The efficiency of light absorption decreased after the application of FR light pulses. These observations explain the higher growth rate, in terms of thallus expansion, after R than after B end-of-day light pulses and FR treatments. The possible action of phytochrome and a B light photoreceptor in the control of growth and pigmentation in Porphyra umbilicalis is suggested.
Two New Anthraquinones from Digitalis cariensis
Authors: Imre Sedat , Ertürk Sıdıka , Imre Zeliha 
Published: August 2018

Abstract
Two new minor anthraquinones, ω-hydroxydigitoemodin (1) and ω-hydroxyziganein-1-methyl ether (4), have been isolated from Digitalis cariensis. Their structures were elucidated on the basis of spectral analysis and 1 was also confirmed by synthesis.
Inhibition of State Transition and Light-Harvesting Complex II Phosphorylation-Mediated Changes in Excitation Energy Distribution in the Thylakoids of SANDOZ 9785-Treated Plants
Authors: Joshi Manoj K. , Mohanty Prasanna , Bose Salil 
Published: August 2018

Abstract
Thylakoids isolated from SAN 9785 (4-chloro-5-dimethylamino-2-phenyl-3(2H)-pyridazi-none)-treated pea plants showed an inhibition of “state transition” and the light-harvesting complex II (LHC II) phosphorylation-mediated changes in the energy distribution between photosystem II (PS II) and photosystem I (PS I) as measured by a decrease in PS II and an increase in PS I fluorescence yield. Interestingly, in these thylakoids the extent of phosphorylation-induced migration of light-harvesting complex (LHC II-P) to non-appressed mem­brane regions was only marginally inhibited. We propose that the suppression in the ability for “state transition” by SANDOZ 9785 (SAN 9785) treatment occurs due to a lack of effec­tive coupling of the migrated LHC II-P and PS I. Since we observed a decrease in the antenna size of PS I of the treated plants, the lack of effective coupling is attributed to this decrease in the antenna size of PS I.
Studies on Activation of H3 Histamine Receptor: A Mechanistic Model
Authors: Karpińska Grażyna , Mazurek Aleksander P. 
Published: August 2018

Abstract
The recognition and the activation mechanism of the H3 histamine receptor was studied based on quantum-chemical calculations. A mechanistic model proposed both for recognition and activation stage clarifies different properties of histamine and α-methylhistamine at the H3 receptor. Interaction with a hypothetical receptor sites leads to the opening of the intramolecular hydrogen bonding in histamine, whereas the α-methylhistamine remains in closed conformation.
Kinetic Studies of Protochlorophyllide Reduction in vitro in the Greening Mutant C-2A' of the Unicellular Green Alga Scenedesmus obliquus
Authors: Urbig Thomas , Knaust Rosemarie K. C , Schiller Hilmar , Sengera Horst 
Published: August 2018

The NADPH-protochlorophyllide oxidoreductase, an enzyme catalysing the light-driven conversion of protochlorophyllide to chlorophyllide, was studied in the greening mutant C- 2A′ of the unicellular green alga Scenedesmus obliquus. Studies of the enzyme activity in
vitro showed strong dependence on the presence of glycerol and the detergent Triton X-100. Prerequisite for the formation of a photoactive enzyme complex is a sufficient preincubation time with the substrates PChlide and NADPH. A continuous assay system, reading the absorbance increase at the wavelength of chlorophyllide, was used to determine the kinetic constants. The Km value for NADPH is 4.2 μᴍ, the Vmax is 5.9 pmol · s-1. The Km and Vmax for protochlorophyllide are 0.19 μᴍ and 6.5 pmol · s-1, respectively. The pH-dependence of the reaction exhibits a broad maximum between pH 7-8.5 typically for an enzyme active during chloroplast development, when pH-changes might be expected.
The obtained kinetic data outline that the light dependent formation of chlorophyll in vivo is not limited by the substrates PChlide and NADPH, indicating that only light is the triggering factor in the very early greening process.
Accumulation and Biosynthesis of Solanapyrone Phytotoxins by Ascochyta rabiei
Authors: Benning Gregor , Barz Wolfgang 
Published: August 2018

Abstract
The biosynthesis of the phytotoxins solanapyrone A , B and C produced by the phytopathogenic fungus Ascochyta rabiei has been investigated. To optimize feeding conditons for the tracer experiments the growth of the fungus and the accumulation of the toxins in submers culture were determined. The accumulation kinetics revealed that formation of the toxins occurs in the stationary phase of the growth indicating that synthesis of solanapyrones follows a typical pattern of secondary metabolism. Incorporation experiments with sodium [1-14C]- and [2-13C]acetate were performed and the NMR-spectroscopically determined labelling pattern of the 13C-enriched solanapyrone A compound confirmed that the carbon skeleton of this compound is formed via the polyketide pathway. The biosynthetic route to solanapyrone B is discussed.
Europium- and Dysprosium-Ions as Probes for the Study of Calcium Binding Sites in Photosystem II
Authors: Burda K. , Strzałka K. , Schmid G. H. 
Published: August 2018

Abstract
Trivalent lanthanide cations are suitable probes for Ca2+-binding sites in photosystem II (PS II). PS II membranes prepared from Nicoticinci tabacum, intact and depleted of the extrinsic polypeptides were exposed to lanthanide ions (Dy3+ and Eu3+). Small concentrations of dysprosium and europium ions enhance oxygen evolution under short saturating flashes. Higher concentrations of the rare earth cations cause the release of the three extrinsic peptides (17, 23 and 33 kDa) and reduce O2 yield. The reactivation of the PS II membranes, thus depleted of the 33 kDa subunit, by Ca2+ ions is not possible. Comparing Eu3+ with Dy3+ in this effect shows that Eu3+ is more effective than Dy3+, because a lower Eu3+-concentration in comparison to that of Dy3+ inactivates O2-evolution. The differences between europium and dysprosium can be explained by their different ionic radius. Our results suggest the existence of two Ca-binding regions: one with a low affinity for calcium would be located on the contact surface of the 23 and 33 kDa proteins and the second one with a high affinity, should be located close to the Mn-cluster and to tyrosine-161 (Z ). The more tightly-bound calcium would be responsible for the activity of the PS II system.
Spatial Attractors in Aggregation Patterns of Dictyostelium discoideum
Authors: Steinbock Oliver , Müller Stefan C. 
Published: August 2018

Abstract
Chemotactic cell motion in aggregation patterns of the slime mould Dictyostelium discoideum is analyzed by a computerized cross-correlation method. In this excitable medium the movement of amoebae is selforganized by signals of cAMP that propagate as rotating spirals or expanding concentric circles (target patterns). A vortex-like rotation of cells is found close to the core of spiral waves, with a maximum velocity of 15 μm/min. Cell motion and spiral tip orbiting follow an opposite sense of rotation. The calculation of streamlines of the most probable trajectories reveals the exsitence of a closed curve (radius ≈ 130 μm) corresponding to the boundary of the spiral core. This spatial-limit cycle attracts the amoebae on rotational paths and leads to the formation of a cell-free disk in the centre of the pattern. In contrast, pacemakers of target patterns organize cell movement in a radial, star-shaped motion, leading directly to the formation of central mounds.
Flavonoid Aglycones from the Leaf Surfaces of Some Artemisia spp. (Compositae-Anthemideae)
Authors: Valant-Vetschera Karin M. , Wollenweber Eckhard 
Published: August 2018

Abstract
Several species of the large genus Artemisia have been analysed for the flavonoid aglycone composition of their leaf exudates. These species belong to different taxonomic groups within Artemisia. Flavone and flavonol aglycones were found as the major flavonoid constituents of the leaf exudates. Many of these compounds were 6-methoxylated, with additional substitutions at the 7-, 3′-and 4′-position of the molecule. In addition, 7,4′-substituted apigenin and luteolin derivatives and rarely also coumarin derivatives were encountered in some species. The observed substitution trends are in accordance with literature data. Taxonomic and eco­logical aspects are briefly discussed.
Antioxidant Protection of Egg Lecithin Liposomes during Sonication
Authors: Gabrielska J. , Sarapuk J. , Przestalski S. 
Published: August 2018

Abstract
When model membranes are prepared by ultrasonic treatment of polyunsaturated phos­pholipids, radical production can induce a partial degradation of the polyunsaturated fatty acyl chains and the formation of lipid hydroperoxides. A suitable antioxidant employed dur­ing liposome preparation is able to protect them against lipid peroxidation. This work con­tains the results of studies on egg lecithin liposomes with incorporated antioxidants that were supposed to play the protective role mentioned. As it has been shown the antioxidant com pounds used ensured a 40-60% , i.e., satisfactory protection of liposomes after 30 min sonication. Possible practical applications are discussed.
Dihydropyoverdinsulfonsäuren - Zwischenstufen bei der Biogenese? / Dihydropyoverdin Sulfonic Acids - Intermediates in the Biogenesis?
Authors: Schröder H. , Taraz J. Adam. K. , Budzikiewicz H. 
Published: August 2018

Abstract
From the culture media of Pseudomonas aptata 4b and of Pseudomonas fluorescens ATCC 13525 5,6-dihydropyoverdin-7-sulfonic acids could be isolated. Their possible role in the biogenetic pathway leading to the pyoverdins will be discussed