bluuebunny/crossref_metadata_2025_split huggingface dataset:
Flavone-C-Glycosides from the Mosses Plagiomnium elatum and Plagiomnium cuspidatum
Authors: Anhut Siegbert , Biehl Jutta , Seeger Tassilo , Mues Rüdiger , Zinsmeister H . Dietmar 
Published: August 2018

In Plagiomnium elatum the new di-C-glycosides 6-C-β-D-glucopyranosyl-8-C-α-L-rhamnopyranosyl- luteolin (Elatin) and 6-C-hexosyl-8-C-rhamnosyl-chrysoeriol were detected. Furthermore four known flavone-C-glycosides were identified. The main glycosides of Plagiomnium
cuspidatum are 6-C-glucosyl-7-O-glucosides of apigenin, luteolin and chrysoeriol respectively.
Understanding the Topography of the Photosystem II Herbicide Binding Niche: Does QSAR Help?
Authors: Huppatz John L. , McFadden Helen G. 
Published: August 2018

Abstract
For thirty years the study of Quantitative Structure Activity Relationships (QSAR) has been an active area of research aimed at developing an understanding of the interactions be­ tween inhibitors of photosynthetic electron transport and the herbicide binding site in the Photosystem II (PS II) reaction centre. Many QSAR studies of PS II inhibitors with diverse chemical structures have emphasized the hydrophobic nature of the binding domain, with lipophilicity being the dominant determinant of Hill inhibition activity. The cyanoacrylate classes of PS II inhibitors also show a diversity of active structures and considerable variation in inhibition potency with minor alterations to structure. QSAR analysis and examination of chirality in cyanoacrylate inhibitors has also shown the importance of steric factors in determining activity. Different modes of binding for different classes of cyanoacrylates have been identified; a classical urea-type relationship between activity and hydrophobicity and another type of interaction in which the lipophilicity or electronic nature of phenyl substituents plays little part and the size of the substituents is of primary importance. Because size and shape are parameters of great importance in determining the topography of a binding site, QSAR studies of flexible PS II inhibitors such as cyanoacrylates will continue to be important in elucidating the intricacies of inhibitor/PS II interactions.
Electron Transport from QA to Thymoquinone in a Synechococcus Oxygen-Evolving Photosystem II Preparation: Role of QB and Binding Affinity of Thymoquinone to the QB Site
Authors: Satoh Kazuhiko , Kashino Yasuhiro , Koike Hiroyuki 
Published: August 2018

Abstract
We have recently shown that binding affinities of benzoquinones can be estimated by two methods in photosystem (PS) II particles (K. Satoh et al., Biochim. Biophys. Acta 1102, 45-52 (1992)). Using these methods we calculated the binding affinity of thymoquinone (2-methyl-5-isopropyl-p-benzoquinone) to the QB site and studied how the quinone accepts electrons in oxygen-evolving PS II particles isolated from the thermophilic cyanobacteria, Synechococcus elongatus and S. vulcanus. The results are as follows: (1) The binding constant of thymoqui­ none to the QB site determined by several methods was around 0.33 mᴍ . (2) At low thymoquinone concentrations the quinone was supposed to accept electrons via QB-plastoquinone, whereas at high concentrations the quinone seemed to bind to the QB site and accept an electron directly from Q-
A. Lower rates of photoreduction of the quinone at high concentrations were attributed to a slower turnover rate of the quinone at the QB site than that of endogenous plastoquinone. (3) A model for the function of plastoquinone at the QB site, which can explain all the results, was presented. According to this model, the plastoquinone molecule at the QB site is not replaced by another plastoquinone molecule. Instead, it transfers electrons to pool plastoquinone molecules by turning over its head group but remaining its long side chain bound to the PS II complexes.
Bicarbonate-Reversible Inhibition of Plastoquinone Reductase in Photosystem II
Authors: Govindjee  
Published: August 2018

Abstract
In this paper the current status of the so-called bicarbonate effect is presented. Several chemicals (such as formate, azide, nitrite and nitric oxide) are known to inhibit the two-electron gate of photosystem II (PS II). A remerkable slowing down of QA
- reoxidation and an increase in equilibrium [QA
- ] have been observed after the second or the subsequent, but not the first, flash when thylakoid membranes are treated with formate, etc. And, significantly, these effects are totally and uniquely reversed upon bicarbonate addition. The current hypothesis is that bicarbonate functions as a proton shuttle that stabilizes the binding niche of QB
- and stimulates platoquinol formation. This bicarbonate effect must involve both the D 1 and D 2 proteins since various herbicide-resistant D 1 mutants (e.g., D 1 -S264A , D 1 -L275F), as well as some D 2 mutants (e.g., D 2 -R251S, D 2 -R 233Q) have been found to be differentially sensitive to formate. The D 2-arginine (233, 251) effects are specific since D 2 -R 139H mutant and an­ other mutant in which an extra arginine was inserted, between F 223 and E 224 , behaves like the wild type. Data in the literature suggest that the bicarbonate binding must also involve Fe in the PS II QA-Fe -QB complex. In contrast, the QA-Fe -QB complex and the two-electron gate of both green and purple photosynthetic bacteria, including the M -E 234 G , Q and V mutants, are insensitive to bicarbonate-reversible inhibitors. We will also address the question of the nature of the active species involved and the possible role of bicarbonate in vivo.
Rare Flavonoid Aglycones from Anaphalis margaritacea and Two Gnaphalium Species
Authors: Wollenweber E. , Fritz H. , Henrich B. , Jakupovic J. , Schilling G. , Roitman J. N. 
Published: August 2018

Abstract
Anaphalis margaritacea, Gnaphalium chilense and G. microecephalum have been analyzed for flavonoid aglycones deposited externally on aerial parts. Anaphalis was found to produce, among others, several rare flavonoids, all of which are O-substituted in position 6 and mostly also in position 8. Both Gnaphalium species exhibit 3,5-dihydroxy-6,7,8-trim ethoxyflavone as the major exudate flavonoid.
Acylated Anthocyanins from Flowers of Cineraria, Senecio cruentus, Red Cultivar
Authors: Terahara Norihiko , Toki Kenjiro , Honda Toshio 
Published: August 2018

Abstract
The structures of the two pigments in the red Cineraria, Senecio cruentus, flowers have been identified as malonylcaffeylcyanidin 3,3′-diglucoside (2) and as its demalonyl compound (1), new anthocyanins, by using chromatographic and spectroscopic techniques involving UV-VIS, IR, FAB-MS and NMR . In a neutral aqueous solution, the acylated anthocyanins retained their colorings for a long time.
Reconstitution of Light-Harvesting Complexes from Chlorella fusca (Chlorophyceae) and Mantoniella squamata (Prasinophyceae)
Authors: Meyer Monika , Wilhelm Christian 
Published: August 2018

Abstract
Reconstitution experiments of light-harvesting complexes were performed with the green alga Chlorella fusca and the chlorophyll c-containing prasinophyte Mantoniella squamata using a modified method according to Plumley and Schmidt [Proc. N atl. Acad. Sei. U .S.A . 84, 146 -150 (1987)]. Changing the pigment supply quantitatively or qualitatively in the reconsti­tution mixture homologous and heterologous reconstitutes were obtained. In contrast to higher plants, light-harvesting polypeptides from green algae are able to bind the chlorophylls as well as the xanthophylls in different stoichiometries. Heterologous reconstitutes of M . squamata polypeptides give further evidence for a rather high flexibility of pigment recog­nition and binding. This is the first report of successful reconstitution of a chlorophyll c-binding protein. Contrary to chlorophyll c-less light-harvesting complexes, the reconstitution of M . squamata is strongly pH-controlled. In summary, the results give evidence for a high specificity of porphyrin ring recognition and variability in xanthophyll binding capacity. Therefore, it is suggested that at least in algal light-harvesting proteins chlorophyll organiza­tion may be determined by other mechanisms than xanthophyll binding.
X-Ray Studies on Phospholipid Bilayers. XIII. Interactions with Gentamicin
Authors: Suwalsky M. , Frías J. 
Published: August 2018

Abstract
This study deals with the structural perturbations that the aminoglycoside antibiotic gentamicin (GENT) can produce to phospholipid bilayers. Two multibilayer systems, one built-up of dimyristoylphosphatidylcholine (DMPC) and the other of dimyristoylphosphatidylethanolamine (DMPE) were allowed to interact with GENT. The experiments were performed in both a hydrophobic and a hydrophilic medium below the phospholipid main transition tem­peratures. X-ray diffraction techniques were used to determine the extent of the perturbation induced by GENT. The maximum effect was attained when GENT interacted with DMPC in the hydrophobic medium. On the other hand, GENT in aqueous solutions was unable to per­turb in any significant extent the structure of the phospholipids under study.
Fructose 1,6-Bisphosphatase in Chlorella kessleri Grown in Red or Blue Light
Authors: Grotjohann N. 
Published: August 2018

Abstract
Total activity of FBPase of Chlorella kessleri grown either in blue or in red light o f equal fluence rates differs (26.8 and 61.0 nmol · min-1 · mg protein-1) in crude cell extracts prepared at pH 8.5. The difference largely depends on FBPase II, an enzyme species assumed to be located in the chloroplast. FBPase II is strongly influenced by reducing agents. Addition of DTT, however, does not compensate for the difference in activities. Although it leads to a higher increase (197%) in the activity of the enzyme from blue than in that of the enzyme from red light conditions, the final activities (79.7 and 133.1 nmol · min-1 · mg protein-1) still differ by a factor of 1.67.
In contrast to alkaline conditions the activity is approx. equal when crude cell extracts are prepared at pH 6.0. It is 62.7 nmol · min-1 · mg protein-1 in blue light and 70.7 in red light. Under these conditions DTT enhances both activities equally (189 and 201 nmol · min-1 · mg protein-1). These results indicate that the observed difference in enzyme activity at pH 8.5 does not result from different enzyme quantities.
At pH 8.5 the mole mass of FBPase II is 88 kD a, while it is 1349 kD a at pH 6.0 under both light conditions. The smaller mole mass represents the monomeric form of the enzyme. The previously assumed pH-dependent oligomerization/dissoziation [8 ], which is generally proven, is therefore not responsible for the different activities of the enzyme from cells grown in red or in blue light. However, the monomeric form seems to possess a higher stability when prepared from cells from red light conditions.
The different stability and activity of FBPase II under alkaline conditions are discussed in context with an altered carbohydrate metabolism in Chlorella kessleri grown autotrophically in different wavelengths of light
Photoregulation of Nitrogen Metabolism and Protein Accumulation in the Red Alga Corallina elongata Ellis et Soland
Authors: Figueroa F. L. 
Published: August 2018

Abstract
Red and blue light pulses of 5 min applied together with 45 μM KNO3 stimulated the nitrate uptake and reduction and the assimilation of ammonium in darkness in the red alga Corallina elongata. Nitrate reductase and glutamine synthetase activities were increased in darkness after the application of both red and blue light pulses. Red light produced a dramatic increase in enzyme activities after the first hour in darkness but after 4 h the effect of blue light pulses was greater. The photostimulation of nitrogen metabolism was correlated with light-regulated accumulation of soluble proteins. Nitrogen incorporation, assimilation of ammonium, accu­mulation of total proteins and the increment in total intracellular nitrogen was greater in N-limited algae (C:N = 17.3) than in N-sufficient algae (C :N = 10.3) after the application of light pulses and nitrate. Because the stimulant effects of red and blue light on N-metabolism were partially reversed by far-red light, the possible involvement of the photoreversible red/ far-red photoreceptor, phytochrome, is proposed. In addition, the blue-light effect seems to be mediated by a specific B-light photoreceptor besides phytochrome due to the different time course of the response and the extent of the stimulation after blue compared to red light pulses.
Translocation of Adenine Nucleotides in the Mitochondria of Male Sterile and Male Fertile Sorghum
Authors: Arora J. , Nath P. , Sane P. V. 
Published: August 2018

Abstract
The translocation of ATP from the inside to the outside of the mitochondrial membrane has been studied in a male sterile (2219 A) and a male fertile (2219 B) line of sorghum. The translocation of ATP was found to be substantially lower in case of mitochondria from the male sterile line. The affinity of adenine nucleotides to the translocator proteins of the mito­ chondrial membrane was found to be almost one half in case of 2219 A as compared to 2219 B when the Km for ATP-ADP was determined by two different assays. It is proposed that the inadequate supply of ATP in the cytosol resulting from its inefficient translocation may con­ tribute to the male sterility in this line.
Inhibition of Dihydrofolate Reductase by Mofebutazon
Authors: Strehl Elke , Schneider Ingrid , Elstner Erich F. 
Published: August 2018

Abstract
Mofebutazon, Dihydrofolate Reductase, Non-Steroidal Antiinflammatory Drugs (NSAIDs) Mofebutazon, in contrast to phenylbutazon, inhibits dihydrofolate reductase in a concentration-dependent manner. An apparent for mofebutazon and dihydrofolate reductase in the presence of NADPH as electron donor and dihydrofolate as electron acceptor of approx­imately 0.2 mM was calculated.
Antitumoral Effect of Bleomycin + Dolomite Combination Treatment, in Mice Bearing Ehrlich Ascites Carcinoma
Authors: Scheller S. , Krol W. , Skirmuntt K. , Zydowicz G. , Shani J. 
Published: August 2018

Abstract
Dolomite, a mineral composed of magnesium and calcium carbonates, potentiates the antitumoral activity of bleomycin: While 40 days after inoculation, no mice survived the Ehrlich ascites tumor burden, 44% of them survived it after bleomycin treatment, and 63% after a simultaneous treatment of bleomycin and dolomite. The beneficial antitumor effect of dolomite is probably related to its high content (12.8%) of magnesium
Induced Accumulation and Potential Antioxidative Function of Rutin in Two Cultivars of Nicotiana tabacum L.
Authors: Steger-Hartmann Thomas , Koch Ulrich , Dunz Thomas , Wagner Edgar 
Published: August 2018

The rutin (quercetin-3-rhamnosyl-glucoside) content of two tobacco cultivars (Nicotiana tabacum L.) which differ in their ozone-sensitivity was assayed after exposure to various rutininducing stimuli. In the growth-chamber, UV radiation in combination with white light led to the accumulation of similar amounts of rutin in both cultivars. Treatment with radical producing agents (tert-butylhydroperoxide and paraquat) also led to rutin accumulation. In this case, the rutin content was higher in the tolerant cultivar. The rutin content was also higher in the tolerant cultivar upon exposure of the plants on an out-door stand, even when the UV-part of the sun spectrum was excluded by cut-off filters.
The potential role of rutin as antioxidant was tested with an ion leakage assay. Plants with relatively high rutin content were less sensitive towards paraquat-induced ion leakage than plants without rutin. Thus, the higher rutin content of the ozone-tolerant cultivar Bel B may well contribute to its tolerance against oxidative stress.
Involvement of Two Different Photoreceptors in the Light Regulation of Glutamine Synthetase Activity in a Chlorophyll-Free Chlorella Mutant
Authors: Meya Gudrun , Kowallik Wolfgang 
Published: August 2018

Glutamine synthetase (EC 6.3.1.2) activity of a non-photosynthetic mutant of Chlorella kessleri is markedly enhanced under blue and slightly increased under red light. In both cases, the effect is largest after 6 h of irradiation. In blue light, saturation is reached at about 10 μEm-2 s-1; in red light, it is not even indicated at 62 μE m-2 s-1.
Semilogarithmic plots of both intensity dependencies reveal different slopes, indicating envolvement of two separate photoreceptors. This feature is supported by different effects of pulse irradiation: The response to 15 min of red light irradiation (λmax 650 nm) increases in subsequent darkness. It reaches the same value as in continuous light after 6 h. The response to 15 min of blue light irradiation (λmax 441 nm) increases also in subsequent darkness. However, after 6 h it reaches only 30% of the value obtained by continuous irradiation.
It is concluded that, glutamine synthetase of Chlorella is controlled by two different photoreceptors both independent of photosynthesis. There is evidence of two forms of glutamine synthetase, the intracellular distribution and specific light regulations of these are discussed.
Product Autofluorescence Activation in the Cytochrome P450 Monooxygenase System
Authors: Enoch Dieter Müller 
Published: August 2018

The relative increase of the 7-ethoxycoumarin-O-deethylase and the 6,7-dimethoxycoumarin- O-demethylase activities were found 93 and 236% using a reconstituted cytochrome P 4502B 1 :NADPH-P450 reductase system by adding to the reaction mixtures their own products. The assays were irradiated during the reactions with the excitation wavelength maximum of their products umbelliferone (λE = 365 nm) or scopoletin (λE = 398 nm), respectively. Addition of the products to the reaction mixtures without irradiation (dark reaction) had no activating effect on the specific activities of the 7-ethoxycoumarin-O-deethylase or the 6,7-dimethoxycoumarin-O-demethylase. The relative increase of the specific activities is dependent on the excitation light intensities and was at maximum when the light intensity at the sample cuvette was 0.4 mW/cm2.
The activation energies of the P 4502B 1-dependent 7-ethoxycoumarin-O-deethylation reaction obtained from Arrhenius plots with and without added umbelliferone and irradiation with λE = 365 nm are 14.7 kJ/mol and 33.5 kJ/mol, respectively, in the temperature range of 27-37 °C. The irradiation energy of the fluorescent product umbelliferone change the catalytic mechanism, which has a two times lower activation energy in the presence of the irradiated product umbelliferone.
Umbelliferone and scopoletin have highest fluorescence intensities in the wavelength range of the blue light (440-480 nm). The photochemical action spectrum of the 7-ethoxycoumarin-O-deethylase of the P4502B 1:reductase system is also found to be in the wavelength range of 420-470 nm. No activation effect was seen with irradiating light lower than 400 nm. Obviously the fluorescence light of the products are due for the extremely high activation effect. This is the first report that the products umbelliferone and scopoletin are photoreceptors and phototransducers.
Partially N-Deacetylated Chitin Fragments are Strong Elicitors for (+)-Pisatin Induction in Epicotyls of Pea
Authors: Kobayashi Akio , Akiyama Kohki , Kawazu Kazuyoshi 
Published: August 2018

Abstract
Chitosan derivatives classed into three groups according to their molecular size were examined for the relationships between degree of N -acetylation and phytoalexin (+)-pisatin-inducing activity in pea epicotyl assay. Partially N-deacetylated chitin with degree of N-acetylation 56% (DAC 56%) was the most potent inducer of (+)-pisatin among sparingly water-soluble polysaccharides including chitosan (degree of N -acetylation 0%), DAC 32%, and chitin. Among the intermediate-sized molecules obtained from degradation of the chitosan and the DACs by NaNO2, the chitosan fragment was the most powerful elicitor for (+)-pisatin induc­tion. The NaNO2-degraded DAC 56% exhibited a com parable activity to the NaNO2 -degrad-ed chitosan at low concentrations. The NaNO2-degraded fragments as well as the native poly­mer induced a relatively high amount of (+)-pisatin, while the acetone precipitate of chitosan oligomers from the HCl-catalyzed hydrolysate and their partially N-acetylated derivatives ex­hibited a moderate (+)-pisatin-inducing activity. These findings suggest the possibility that partially N-deacetylated chitin fragments could be one of the most promising elicitors in the pea system.
Histone Acetylation is not Affected by Chloroacetamides in vitro
Authors: Kring Friedhelm , Böger Peter 
Published: August 2018

Abstract
The effects of chloroacetamides on the acetylation of histone protein in maize (Zea mays) were studied in an in vitro assay. Neither alachlor nor metazachlor showed any influence on both of the investigated acetylating enzymes, the nuclear histone acetyltransferase A and the cytoplasmic histone acetyltransferase B. Furthermore, an effect of these herbicides on deacetylation of histones could be excluded.
Natural Inhibitors of Germination and Growth, VII Synthesis of Ribulosebisphosphate Carboxylase in Darkness and Its Inhibition by Coumarin
Authors: Burghardt Helena , Brunner Harald , Oelmüller Ralf , Lottspeich Friedrich , Oster Ulrike , Rüdiger Wolfhart 
Published: August 2018

Abstract
Dedicated to Prof. Aloysius Wild on the occasion of his 65th birthday Lepidium sativum, Cruciferin, Ribulosebisphosphate Carboxylase, Inhibition of Transcription Cress (Lepidium sativum) seeds were germinated in darkness. Seedlings were investigated for soluble proteins by SDS-PAGE. Two proteins were identified by microsequencing: the small subunit of ribulosebisphosphate carboxylase (SSU) and the alpha subunit of the storage protein cruciferin. Net synthesis of small and large subunits of ribulosebisphosphate carboxylase (SSU and LSU) was investigated by Western blot. Net synthesis of both subunits was inhibited by coumarin. To the contrary, net synthesis of cruciferin was increased by coumarin. With specific cDNA probes, we determined steady state levels of the corresponding mRNAs (rbcS mRNA for SSU, rbcL mRNA for LSU). Both mRNAs can be detected in dry seeds; their amount increases during germination in the dark. Incubation with coumarin inhibits this increase. Inhibition of development by coumarin on the level of transcription is discussed.
Symbiotic Effectivity of Four Phaseolus vulgaris Genotypes after Inoculation with Different Strains of Rhizobium under Controlled Conditions
Authors: Epping Bernhard , Hansen Alexander P. , Djalali Bahman , Martin Peter 
Published: August 2018

Abstract
Four varieties of P. vulgaris L. were tested for their symbiotic nitrogen fixation effectivity in combination with nine different strains of Rhizobium leguminosarum bv. phaseoli and Rhizobium tropici. Plants were grown under controlled conditions and harvested 23 days after planting. Acetylene reducing activity, total N-content and dry weight of individual plant components were determined. Significant differences due to plant x bacterium interaction were assessed by ANOVA, especially for the total nodule mass per plant and the acetylene reducing activity per nodule dry weight. Data for acetylene reducing activity per plant correlated highly with the corresponding data for the total N-content. The comparison of the total N-content in symbiotically grown plants, lacking supply of mineral N, with plants luxuriously supplied with mineral N (relative N-accumulation rate) revealed high values (between 60% and 70% of maximal N-uptake) for some symbiotically active plant/bacterium combinations for this early developmental stage of the symbiosis N2 fixation potential for such symbioses.