bluuebunny/crossref_metadata_2025 huggingface dataset:
Interrelationship of Oxygen and Nitrogen Metabolism in the Filamentous Cyanobacterium Oscillatoria chalybea
Authors: Bednarz J. , Höper S. , Bockstette M. , Bader K. P. , Schmid G. H.
Published: August 2018

Filamentous Cyanobacteria. Hydrogen Peroxide, Photosystem II. Nitrogen Metabolism By means of mass spectrometric analysis we have been able to demonstrate H 20 2-production and its decomposition by photosystem II in thylakoids of the filamentous cyanobacterium Oscil­ latoria chalybea. This H2O2-production and its quasi simultaneous decomposition by the S-state system can be readily demonstrated in flash light illumination (K. P. Bader and G. H. Schmid, Biochim. Biophys. Acta 936, 179-186 (1988)) or as shown in the present paper in continuous light at low light intensities. These light conditions correspond essentially to the culturing condition of the organism on nitrate as the sole nitrogen source. Under these conditions, however, electron transport between the two photosystems seems to be mostly disconnected and respiratory activity practically non existent. Under these conditions, on the other hand, nitrate reductase is induced and nitrate reduced. The present paper addresses the question how this organism might solve the metabolic problems of nitrate reduction with such an electron transport system. Tested under high light intensities under which the organism would not grow at all, electron transport between the two photosystems is optimally linked and the system funnels part of its photosynthetically pro­duced electrons into a conventional cyanide-sensitive respiratory electron transport chain and even into an alternative Sham-sensitive (cyanide-insensitive) respiratory chain. This is made possible by the overweight of photosystem II capacity in comparison to photosystem I activity as reported in this paper. Under the conditions described, the cyanobacterium grows also on ar­ginine as the sole nitrogen source. Most interestingly under these conditions nitrate reductase induction is not shut off as is the case with other aminoacids like ornithine or alanine in the medium. Nitrite reductase is not induced in these bacteria, if grown on arginine as the sole nitrogen source. This observation is discussed in context with the fact that arginine is a major storage product (cyanophycin) in this organism and that the observed photosystem II mediated H2O2-production might be correlated with arginine metabolism.
Der protektive Effekt von D2O bei Bakterien (E. coli) / he Protective Effect of Heavy Water (D2O) on Bacteria (E. coli)
Authors: Papadimitriou C. , Wenzel M.
Published: August 2018

E. coli suspended in D2O showed a better survival than in H2O when the bacteria were treated with various damaging agents like UV , heat and freezing. On the contrary E. coli grown in D2O - containing media - therefore being fully deuterated - were more sensitive than normally grown bacteria.
Flower Induction in Seedlings of Asparagus officinalis L. by N-Phenylcarbamates
Authors: Yanosaka Keiko , Iwamura Hajime , Fujita Toshio
Published: August 2018

A series of N-phenylcarbamates induced flowers in one-month-old seedlings of Asparagus officinalis L. Ninety to 100% of the plants flowered when the seeds were germinated in the presence of the most potent members of this class. The flowering occurred only once at the top of the seedlings, which then continued to grow normally. This made it possible to select the commer­cially preferred m ales of this dioecious plant at the seedling stage. Both male and female flowers were fertile, so cross-breeding was possible between flowering seedlings as well as between flowering seedlings and adults that had grown normally. Activity of flowering induction was not related with inhibition of photosystem II activity.
Algorithm for Construction of Phylogenetic Trees
Authors: Tohá José , Soto M. A. , Chinga H.
Published: August 2018

An algorithm is described for the construction of phylogenetic trees.

The algorithm is based on the progressive correction of data along the tree construction.

For the correction, the average value of the difference between each pair of neighbour elements to the rest of the table is considered.
New 4-Hydroxypyridine and 4-Hydroxyquinoline Derivatives as Inhibitors of NADH-ubiquinone Reductase in the Respiratory Chain
Authors: Chung Kun Hoe , Cho Kwang Yun , Asami Yasuko , Takahashi Nobutaka , Yoshida Shigeo
Published: August 2018

Many derivatives of 2,3-dim ethoxy-4-hydroxypyridine, which were designed from examination of the structure-activity relationship of piericidins, were tested for inhibition of NADH-UQ reductase. The lipophilic side chain of those compounds was indicated to be a key part for activity and its optimal length was conjectured. By the use of two different phases of assay material, intact mitochondria and submitochondria, the size of a membrane effect was shown to depend on the structure of the side chain. 4-Hydroxyquinoline derivatives were also tested for an analogous role in relation to the electron transport function of menaquinone, and they were proven to be inhibitors of NADH-UQ reductase as good as the pyridine derivatives.
Stabilization of Actin Filaments by ATP and Inorganic Phosphate
Authors: Dancker Peter , Fischer Sabine
Published: August 2018

Both inorganic orthophosphate and ATP stabilize actin filaments. This is reflected by a reduced nucleotide exchange and by a protection against filament breakdown by SDS or KI. When the filament-stabilizing effect of ATP was maximal, only about 15% of the actin subunits of the filament had bound one molecule of the nucleotide offered in the stabilizing solution.
Ultrastructure of Epicuticular Wax in Canola
Authors: Conn K. L. , Tewari J. P.
Published: August 2018

Ultrastructure of the epicuticular wax of four commercially grown Canadian cultivars of canola (Brassica campestris cvs. Tobin and Candle, B. napus cvs. Altex and Westar) was investigated. Freeze-drying and air-drying methods of specimen preparation for scanning electron microscopy were compared. The freeze-drying method resulted in disruption and possible washing away of wax crystals, whereas there was no visible damage with the air-drying method. The freeze-drying method provided evidence for an amorphous layer of wax beneath the wax crystals. Ultrastructure of wax in the four cultivars was generally similar. All cultivars had an evenly distributed layer of wax crystals superimposed on an amorphous layer of wax. Some trends such as density of wax on leaves and siliques appeared to be species-specific, whereas density of wax on stems did not. There appeared to be at least three types of wax crystals present. These included plate-like, filamentous, and rod-like crystals. The rods were present singly or in blocks.
Deoxyribonucleotide Synthesis in an Escherichia coli Mutant (H 1491) which Lacks Ribonucleotide Reductase Subunit B2
Authors: Harder Jens , Follmann Hartmut , Hantke Klaus
Published: August 2018

An iron-sensitive mutant of E. coli with a Mudl phage insertion in the nrdB gene lacks subunit B2 of the key enzyme of DNA synthesis, ribonucleotide reductase. Nevertheless, these cells are capable of growing in minimal media under anaerobic conditions, indicating a second enzyme or pathway for deoxyribonucleotide synthesis. We here show that ribonucleotide reduction cannot be unambiguously measured in bacterial extracts whereas phosphorylase- catalyzed deoxyribosyl transfer does occur; however these salvage reactions could not function in vivo in the absence of deoxyribosides. It is suggested that the cells possess a specific, anaerobic ribonucleotide reductase which escapes detection under aerobic standard conditions, similar to the situation found in strictly anaerobic methanogens.
Degradation of the Pterocarpan Phytoalexin (—)-Maackiain by Ascochyta rabiei
Authors: Höhl Birgit , Arnemann Martin , Schwenen Ludger , Stöckl Dietmar , Bringmann Gerhard , Jansen Johannes , Barz Wolfgang
Published: August 2018

Ten strains of Ascochyta rabiei pathogenic to chickpea ( Cicer arietinum L.) were shown to be potent degraders of the chickpea pterocarpan phytoalexin ( - )-maackiain (1) ([6aR: 11 aR]-3- hydroxy-8,9-methylenedioxypterocarpan). In degradative studies with mycelial preparations and crude protein extracts seven catabolites could be isolated and structurally elucidated by spectroscopic techniques. The main routes of maackiain degradation are reduction to a 2´-hydroxyisoflavan (2) and oxidation to an 1 a-hydroxy-pterocarp-1,4-diene-3-one (3) with subsequent reductions of the early catabolites in ring A. A catabolic sequence for maackiain is compared with the degradation pattern of pterocarpan phytoalexins observed with other fungi.
Enzyme-Kinetic Studies on the Interaction of Norflurazon with Phytoene Desaturase
Authors: Sandmann Gerhard , Linden Hartmut , Böger Peter
Published: August 2018

Bleaching herbicides inhibit carotene biosynthesis in photosynthetic organisms. The interaction of norflurazon [4-chloro-5-methylamino-2-(3-trifluoromethylphenyl)-pyridazin-3(2H)one] with its target enzyme phytoene desaturase, has been characterized by enzyme-kinetic studies. A Lineweaver-Burk plot showed a non-competitive m anner for norflurazon inhibition. Binding of norflurazon to phytoene desaturase was reversible as dem onstrated by complete replacem ent of bound 14C-labeled herbicide by unlabeled norflurazon. In a linear Dixon plot the ki value for norflurazon was determ ined as 0.09 μм . With the in vitro system from Anacystis used in this study it was possible to perform structure-activity studies with selected m -phenyl-substituted pyridazinones. A linear relationship between inhibitory properties of these compounds and their lipophilicity could be established.
Wirkung von Neocarzinostatin auf E. coli-Mutanten mit defekter DNA-Reparatur / The Influence of Neocarzinostatin on the Colony Forming Ability of E. coli Mutants Deficient in DNA Repair
Authors: Denklau D. , Stahl R. , Köhnlein W.
Published: August 2018

Abstract The colony forming ability of E. coli mutants defective in DNA repair was compared to that of the parent strain AB 1157 after neocarzinostatin treatment. A recA and a recB mutant were most sensitive. The suppression of the recB mutation in the recBC sbcBC mutant, which is as sensitive as the parent strain, indicates that recB is not the primary pathway by which lesions after NCS treatment are repaired. The survival curve of the recBC recF sbcBC mutant, corresponding to that of the recF mutant, further supports this interpretation. The relative resistance of the recBC recF sbcBC mutant suggests that NCS lesions are not only repaired by the recF and recB pathway. An alternative pathway could be the SOS induction, as a lexA m utant also is sensitive to NCS. The sensitivity of the uvrA and polA xthA mutants, however is explained by the involvement of the uvrA and polA gen products in rec repair.
The Short-Term Effects of Inorganic Phosphate on the Levels of Metabolites in Suspension-Cultured Catharanthus roseus Cells
Authors: Kubota Kaoru , Li Xiao-Ni , Ashihara Hiroshi
Published: August 2018

In order to analyze the effects of inorganic phosphate (Pi) on the energy metabolism of suspen­sion-cultured cells of Catharanthus roseus, short-term changes in levels of glycolytic metabolites were monitored after the addition of 1.25 mм Pi to cultures of cells previously cultured in a Pi-free Murashige-Skoog medium for 24 h. The levels of all phosphorylated intermediates of glycolysis examined were found to increase after addition of Pi. The most striking increases were observed in levels of glucose-6-phosphate and fructose-6-phosphate which rose to approximately 8 (after 30 min) and 15 times (after 120 min) their initial values. The levels of ATP and pyrophosphate doubled during the first 30 min of incubation. In contrast, the level of pyruvate decreased significantly during the initial 30 min and then began to increase again for the next 90 min. The short­ term effects of Pi on the rates of synthesis of proteins and RNA were estimated from the rates of incorporation of 14C-labelled amino acids and uridine into the macromolecules. No appreciable stimulation of the synthesis of proteins and RNA was induced by Pi within 120 min after the addition of Pi. Possible mechanisms are discussed that may be involved in the changes in metabo­lism initiated by the addition of Pi to the cultures.
Notes: Separation of 13-and 9-Hydroperoxide Lyase Activities in Cotyledons of Cucumber Seedlings
Authors: Matsui Kenji , Shibata Yasushi , Kajiwara Tadahiko , Hatanaka Akikazu
Published: August 2018

In cucumber cotyledons, both C6
- and C9- aldehyde were formed via hydroperoxide (HPO) lyase activity. Because it has not been elucidated whether these activities are attributed to one enzyme which can cleave both 13-and 9-HPO or to two or more enzymes each of which specifically cleaves 13-or 9-HPO , an attempt to separate HPO lyase activity was done. Ion exchange chromatography separated this activity into two fractions, one of which specifically cleaved 13-hydroperoxylinoleic acid and the other specifically cleaved the 9-isomer. 13-HPO-specific activity was most active at pH 8.0 and 9-HPO-specific one was at pH 6.5. SH -reagents inhibited both the lyases but to different extents.
Cyanoacrylate Inhibitors as Probes for the Nature of the Photosystem II Herbicide Binding Site
Authors: Huppatz John L. , McFadden Helen G. , McCaffery Leslie F.
Published: August 2018

Three series of phenyl-substituted 2-cyanoacrylates were evaluated using simple quantitative structure activity relationships (QSAR) in an attempt to elucidate the nature of the regions of the binding site occupied by different parts of the molecules.

Inhibition of the Hill reaction by substituted 3-phenylamino-2-cyanoacrylates correlated well with the lipophilicity of the substituent. The hydrophobic effect was also dominant when the Hill activity of a series of 3-benzylamino-2-cyanoacrylates was analyzed, although potency was considerably higher in the latter series.

Lipophilicity and the electronic nature of the substituents were not major determinants in the Hill inhibitory activity of a series of substituted phcnoxycthyl 2-cyanoacrylic esters. In this case, a significant correlation was found with the molar rcfractivity (MR) of meta substituents, a parameter reflecting substituent size.

The results indicate that the phenyl moiety of substituted 3-phenylamino- and 3-bcnzyl- amino-2-cyanoacrylates interacts with an essentially lipophilic binding domain, though it is likely that the two series are oriented differently with the 3-bcnzylamino series able to bind with greater affinity. In the phcnoxycthyl ester series, the substituted phenyl group interacts with a different environment, wherein ortho- and we7tf-substitution is tolerated, dependent on the bulk of the substituent, but /wra-substitution is detrimental to affinity for this region of the site.
Hydrophilic Photosystem II Inhibitors: Cyanoacrylate Thiolate Salts
Authors: Phillips John N.
Published: August 2018

Cyanoacrylate thiolate salts such as the sodium salt of ethoxyethyl-3-p-chlorobenzylthio-2-cyano-3-mercapto acrylate have been shown to be relatively slow binding, potent inhibitors of photosynthetic electron transport, that are equally active against thylakoids isolated from atrazine-susceptible and atrazine-resistant Brassica napus seedlings. It has been suggested that their mode of binding involves the substituted benzyl group interacting with the membrane lipids and the thiolate ion interacting in the region of the histidine215 residue of the D1 peptide, close to the non-heme Fe centre. This, together with their slow rate of binding, has led to the thiolate salts being classified as phenol type inhibitors.
Kinetics of Action of Different Photosystem II Herbicides on Thylakoids
Authors: Ducruet Jean-Marc , Creuzet Sophie , Viénot Josiane
Published: August 2018

The kinctics of inhibition of photosystem II electron transfer by different diuron-like herbicides (ureas, triazines, triazinoncs, biscarbamates. uraciles) were studied, mainly by chlorophyll fluorescence measurements. Uracil derivatives and cyanazine, a particular triazinc. were the slowest acting compounds. The half-times of action were strongly temperature-dependent and were of the order of tens of seconds at 5 °C for urea or triazine inhibitors. The role of different limiting steps in the binding process is discussed.
Molecular Modelling Studies on the Binding of Phenylurea Inhibitors to the D 1 Protein of Photosystem II
Authors: Bowyer John , Hilton Mark , Whitelegge Julian , Jewess Philip , Camilleri Patrick , Crofts Antony , Robinson Howard
Published: August 2018

A hypothetical molecular model of part of the D 1 protein of photosystem II, based on the analogous portion of the L subunit of the Rhodopseudomonas viridis reaction centre, has been used to study the binding of an extended hydrophobic phenylurea inhibitor (N,N-dimethyl-carbamoyl)4 -amino-4 ′-chloro-trans-stilbene) (I) to the QB site. The inhibitor was fitted by eye into a cleft in the site, and a limited part of the inhibitor/D 1 complex was energy minimized. The gross orientation of the inhibitor placed the dimethylurea moiety towards the predicted binding domain of the plastoquinone head group, and the stilbene moiety directed along the quinone isoprenoid side chain binding domain, suggesting a similar pathway of approach of the two molecules from the membrane into the binding site. Binding interactions of the inhibitor included hydrogen bonds to the side chain hydroxyl of ser 264 and the peptide carbonyl group of ala 251, with the side chain hydroxyl of ser 268 as an alternative ligand. Numerous hydrophobic contacts were also possible. Although phenylureas do not bind to reaction centres of Rp. viridis, many of the binding interactions to D1 could also be detected in Rp. viridis. However, the β-CH2 and δ-CO2
-groups of glu 212 in Rp. viridis are located in the corresponding region of D1 occupied by the dimethylurea moiety of the inhibitor in our model of its binding to D 1. This may explain why diuron (DCMU) does not bind to Rp. viridis reaction centres.
Differential Sensitivity of 32 kDa-D1 Protein Degradation and Photosynthetic Electron Flow to Photosystem II Herbicides
Authors: Jansen Marcel A. K. , Malkin Shmuel , Edelman Marvin
Published: August 2018

Degradation of the 32 kDa-D1 protein, a photosystem II reaction centre component, was studied as a function of linear electron flow in visible light in the presence of various photosys­ tem II herbicides. Under these conditions, herbicide specific effects on protein degradation were clearly evident. 32 kDa-D 1 protein degradation and electron flow between Qa and Qb proved to be only partially correlated. We conclude that inhibition of protein degradation by PS II herbicides in visible light is not simply correlated to displacement of Qb.
A Rapid Method for Partial mRNA and DNA Sequence Analysis of the Photosystem II psbA Gene
Authors: Naber Dirk , Johanningmeier Udo , van Rensen Jack J. S.
Published: August 2018

Single amino acid substitutions in the D1 protein of photosystem II may cause resistance to various herbicides. In all organisms studied these substitutions are located in or between helices IV and V of the protein. The increasing number of herbicide-resistant organisms necessitates development of a rapid methodology to characterize deviations from the wildtype se­ quence. Here, two procedures are described to identify mutations in the psbA gene, which is coding for D1. These procedures involve the isolation and amplification of DNA and R A and subsequent sequencing reactions without the need to clone the psbA gene. A triazine-resistant and a -susceptible biotype of Chenopodium album were used as model species. An A to G transition, giving rise to a serine to glycine mutation at position 264 in the D1 protein, is found in the resistant plant.
Anacystis Mutants with Different Tolerances to DCMU-Type Herbicides Show Differences in Architecture and Dynamics of the Photosynthetic Apparatus, Depending on Site and Mode of the Amino Acid Exchanges in the D1 Protein
Authors: Koenig Friederike
Published: August 2018

Mutants of Anacystis R2 with different amino acid exchanges in positions 255 and/or 264 in copy I of the psbA gene, leading to different tolerances to DCMU-type herbicides, are com- pared with the respective wild type concerning pigmentation and incorporation of 35S into the D1 protein upon growth in the presence of [35S]methionine. All mutants have shade-type appearance compared to the wild type, although to different extents depending on site and mode of the amino acid exchange in the D1 protein. Except for 3 mutants, there is no correlation between shade-type appearance on one hand and resistance towards a certain inhibitor on the other hand.

Not only the molar ratio of phycocyanin (PC) to chlorophyll (Chi) is higher in all mutants compared to the respective wild type, but also the rate of synthesis of the D1 protein. On the background of different levels of total 35S incorporation within 18 min, D1 synthesis can be related to shade adaptation. Degradation of the D1 protein remains to be thoroughly studied in this context.

No reproducible differences in whole chain electron transport were observed between mutants and wild type.
Negative Cross Resistance; a Possible Key to Atrazine Resistance Management: A Call for Whole Plant Data
Authors: Gressel Jonathan , Segel Lee A.
Published: August 2018

Many photosystem II inhibiting herbicides still inhibit this process in triazine-resistant plants; i.e. they have no cross resistance with atrazine. Five- to twenty-fold lower concentrations of phenolic type herbicidcs and 5-fold less of the active ingredient of pyridate and half as much ioxynil are required to inhibit thylakoid PS II in atrazine-resistant biotypes than in sensitive biotypes; i.e., they even show “negative cross resistance”.

Negative cross resistance may be the major reason that atrazine resistance did not evolve where herbicide mixtures were used, when the mixed herbicide (usually a non-PS II inhibiting acetanilide) also controlled triazine-sensitivc weeds.

Mathematical modeling in principle allows quantification of the very low field levels of herbicides possessing negative cross resistance that could be mixed with atrazine that would stop or delay the evolution of resistant populations without affecting the maize crop. There are few available actual dose response curves of atrazine-resistant vs. susceptible weeds at the whole plant level for herbicidcs exerting negative cross resistance. Thus, “real situation” modeling cannot be done. Data acquisition is called for so that the model can be extrapolated from the thylakoid to the field.
Segregation of Triazine-Resistant Chloroplasts after Introduction into Winter Type Oilseed Rape (Brassica napus L.) by Protoplast Fusion
Authors: Hain R. , Thomzik J. E.
Published: August 2018

Triazine-resistant chloroplasts of the Canadian spring oilseed rape variety OAC Triton were transferred into four German winter oilseed rape lines and two cultivars of double-low quality by means of protoplast fusion. X-irradiation has been used to reduce the amount of nuclear D N A of the spring type cultivar and to promote cybrid formation. RFLP-analysis showed that some regenerants and their progeny carried both types of chloroplasts. In some instances regenerants and progeny containing mixtures of both chloroplasts not kept under selective conditions lost their triazine-resistant chloroplasts completely during further plant growth. Preliminary results of greenhouse and field experiments indicate that volunteer plants can be eliminated by application of 150-300 g/ha metribuzin (SencorR, Bayer AG) in a stand of triazine-resistant oilseed rape of double-low quality.
Cloning a Gene Coding for Norflurazon Resistance in Cyanobacteria
Authors: Chamovitz Daniel , Pecker Iris , Sandmann Gerhard , Böger Peter , Hirschberg Joseph
Published: August 2018

The herbicide norflurazon inhibits carotene biosynthesis in photosynthetic organisms by blocking the enzyme phytoene dehydrogenase (= phytoene desaturase). We have isolated norflurazon-resistant mutants of the cyanobacterium Synechococcus PCC7942. The herbicide- resistance gene from the mutant NFZ4 has been cloned by genetic complementation of the resistance trait in wild type cells. The experiment described here illustrates the usefulness of employing cyanobacteria to clone herbicide-resistance genes in a quick and simple way.
Typical Peroxidative Parameters Verified with Mung-Bean Seedlings, Soybean Cells and Duckweed
Authors: Sandmann Gerhard , Nicolaus Beate , Böger Peter
Published: August 2018

Peroxidation is indicated by several physiological parameters: (1) leakage of cell membranes and production of short-chain hydrocarbons, (2) degradation of cell constituents, (3) inhibition of chlorophyll biosynthesis, (4) accumulation of tetrapyrroles (protoporphyrin IX). (5) inhibition of protoporphyrinogen oxidase by peroxidizers, (6) alleviation of peroxidation by inhibitors of chlorophyll biosynthesis. (7) alleviation of peroxidation by photosynthesis inhibitors (“diuron effect”), (8) counteraction of the diuron effect by glucose (heterotrophic conditions). Such parameters, described and elaborated with microalgae and higher plants, arc verified in this study with soybean cells, duckweed and mung beans. Preliminary data indicate lack of quantitative relationship between inhibition of protoporphyrinogen oxidase, protoporphyrin (IX) formation and peroxidative consequences.
Effect of Thiolactomycin on de novo Fatty Acid Biosynthesis in Plants
Authors: Focke Manfred , Feld Andrea , Lichtenthaler Hartmut K.
Published: August 2018

Thiolactomycin was shown to be a potent inhibitor of de novo fatty acid biosynthesis in intact isolated chloroplasts (measured as [14C]acetate incorporation into total fatty acids). In our attempt to further localize the inhibition site we confirmed the inhibition with a fatty acid synthetase preparation, measuring the incorporation of [14C]malonyl-CoA into total fatty acids. From the two proposed enzymic targets of the fatty acid synthetase by thiolactomycin we could exclude the acetyl-CoA: ACP transacetylase. It appears that the inhibition by thiolactomycin occurs on the level of the condensing enzymes, i.e. the 3-oxoacyl-ACP synthases. We also demonstrated that the two starting enzymes of de novo fatty acid biosynthesis, the acetyl-CoA synthetase and the acetyl-CoA carboxylase, are not affected by thiolactomycin.
Ribulose-1,5-bisphosphate Carboxylase-Binding Chloroplast Thylakoid Membrane Proteins. In vitro Evidence that H+ -ATP Synthase may Serve as a Membrane Receptor
Authors: Süss Karl-Heinz
Published: August 2018

Affinity binding to Sepharose 4 B-immobilized ribulose-1,5-bisphosphate carboxylase (Rubisco) and its isolated small (SSU) and large (LSU) subunits of Nonidet P40-solubilized chloroplast thylakoid proteins has been performed to search for Rubisco membrane receptors in vitro. It was found that Rubisco and both of its isolated subunit types specifically bind the same proteins including H+-ATP synthase, cytochrome ƒ/b6 complex, ferredoxin-NADP+ reductase (FNR) and components of photosystem (PS) II which presumably form multienzyme complexes. PS I was not recognized by Rubisco components. of the Rubisco-binding thylakoid proteins, at least coupling factor 1 (CF1) is shown to form specific complexes with the enzyme as revealed by affinity chromatography and protein hybridization on nitrocellulose filters. Employing the latter approach, the SSU and LSU of Rubisco were observed to bind independently to isolated α and β, but not to γ, δ and ε subunits of CF1. The results indicate that H+-ATP synthase may serve as a Rubisco membrane receptor at least in vitro and suggest that the irreversible inhibition of photophosphorylation by Rubisco [R. T. Furbank et al., Biochim. Biophys. Acta 852,46-54 (1986)] is mainly due to its binding to the α/β subunit pairs of CF1.
X-Ray Induced Inactivation of the Sulfhydryl Enzyme Malate Synthase in the Presence of Various Additives Probing the Extent of Primary and Post-Irradiation Inactivation and Repair by Rapid Screening on the Microlevel
Authors: Durchschlag Helmut , Zipper Peter
Published: August 2018

The sulfhydryl enzyme malate synthase was inactivated by X-irradiation in air-saturated aqueous solution, in the absence or presence of a variety of additives (thiols, antioxienzymes, typical radical scavengers, inorganic salts, buffer components, substrates, products, analogues). Radiation-induced changes of enzymic activity were registered immediately after stop of irradiation and in the post-irradiation period. Repair experiments were initiated by postirradiation addition of dithiothreitol. Additionally, post-irradiation inactivation was modulated by some further additives. Probing the extent of primary and post-irradiation inactivation and repair was accomplished effectively by screening experiments on the microlevel, and by derivation of normalized efficiency parameters which allowed quick comparisons of the various additives with respect to their protective and repair-promotive efficiencies. Correlations between the efficiency parameters were studied by means of binary and ternary diagrams. Most of the substances added before irradiation were found to protect the enzyme against primary and post-irradiation inactivation and to increase the reparability of the enzyme by dithiothreitol, the extent of the effects depending on the nature (and concentration) of the additives used. Our results indicate that both specific protection (by substrates, products, analogues, and by sulfhydryl agents) and scavenging are responsible for the radioprotective efficiencies of the additives.
Ribonucleoside in Milch: Charakterisierung und Bestimmung des Konzentrationsprofils dieser minoren Komponenten über eine Laktationsperiode / Ribonucleosides in Milk: Characterization and Determination of the Concentration Profile of these Minor Components throughout a Lactation Period
Authors: Raezke Kurt-Peter , Schlimme Eckhard
Published: August 2018

The ribonucleosides adenosine, cytidine, guanosine, inosine and uridine as well as the modified components N 1-methyladenosine and N 6 -carbamoylthreonyladenosine were characterized and determined quantitatively as minor constituents in raw bovine milk by use of an automated high performance liquid chromatography system. The studies have shown that except for the colostral phase the ribonucleoside levels are constant throughout the whole lactation period. That means, there is a typical ribonucleoside pattern which is assumed to be speciesspecific.
On the Problem of Season and Cold Dependence of Calcium Transport by Skeletal Muscle Sarcoplasmic Reticulum
Authors: Agostini Bruno , De Martino Luisa , Hasselbach Wilhelm
Published: August 2018

Calcium transport of skeletal muscle sarcoplasmic reticulum from golden hamsters was studied in January and in June on animals kept at 22 °C under natural photoperiod and in January after cold-acclimation at ±2 °C in the dark for 55 days. Crude homogenates from psoas and soleus muscles and from mixed skeletal muscles were used.

No differences were observed in the calcium storing capacity of sarcoplasmic reticulum among the three groups of animals. Kinetic studies on the dependence of the calcium uptake rate on the concentration of free calcium revealed a significant increase of the uptake rates and a decrease of the calcium affinity in the control animals sacrificed in winter as compared to those killed in June. Cold-acclimation in winter leads to a further small reduction of the calcium affinity.

This shift of calcium uptake rate and affinity in the sense of that of a fast-twitch muscle may be related to the functional demands of the cold season and cold-acclimation respectively.
14-Deoxyecdysteroids in an Insect ( Gryllus bimaculatus)
Authors: Hoffmann Klaus H. , Thiry Edeltraud , Lafont Rene
Published: August 2018

Following injection or ingestion of [3H]ecdysone and [3H]2O-hydroxyecdysone, respectively, considerable quantities of 14-deoxyecdysteroids could be extracted from gut and faeces of female adult crickets. The compounds were identified as 14-deoxyecdysone and 14-deoxy-20-hydroxyecdysone on the basis of comigration with reference substances in two HPLC systems and by its mass spectrum (only 14-deoxy-20-hydroxyecdysone). The 14-dehydroxylation is most probably caused by bacteria from the gut lumen. Feeding of [3H]ecdysone resulted in the appearance of labelled 14-deoxyecdysone also in ovaries, fat body, muscles, and rest of the body.
Production of β-Carboline Alkaloids in Transformed Root Cultures of Peganum harmala L.
Authors: Kuzovkina I. N. , Gohar A. , Alterman I. E.
Published: August 2018

Peganum harmala, Hairy Root Cultures, β-Carboline Alkaloids Hairy root cultures of Peganum harmala were established by genetic transformation with Agrobacterium rhizogenes strain A4. In contrast to suspension cultures the root cultures contained high levels of β-carboline alka­ loids (1 -1.5% of dry mass).
Ascorbinsäure-Radikale als Indikator für Waldschäden - EPR-spektroskopische Untersuchungen an Fichtennadeln in vivo / Ascorbic Acid Radicals as Indicator of Damage to Forest - EPR Investigations o f Spruce Needles in vivo
Authors: Stegmann Hartmut B. , Schuler Paul , Ruff Hans-J.
Published: August 2018

Ascorbic Acid Radicals as Indicator of Damage to Forest -EPR Investigations of Spruce Needles in vivo Hartmut B. Stegmann, Paul Schuler
New Flavonoids from the Moss Bryum pseudotriquetrum
Authors: Stein Wolfgang , Zinsmister H. Dietmar
Published: August 2018

Fifteen flavonoids have been isolated from the moss Bryum pseudotriquetrum . The new natural products kaempferol 3-O-galactoside-4 ′-O-glucoside, scutellarein 7-O-glucoside-6′′-malonyl ester, pigenin 7-O-neohesperidoside-6′′-malonyl ester and luteolin 7-O -neohesperi-doside-6″-malonyl ester were amongst them . Flavonols were found for the first time in mosses.
Enzymatic Synthesis of Di-O-Phenylcarboxyl-ß-D-glucose Esters by an Acyltransferase from Oak Leaves
Authors: Gross Georg G. , Denzel Klaus
Published: August 2018

Leaves from oak (Quercus robur) contain an acyltransferase that catalyzes the conversion of β-glucogallin (1-O-galloyl-β-D-glucose) to 1,6-di-O-galloylglucose, an intermediate in the biosynthesis of gallotannins. Substrate specificity studies revealed th at this enzyme was also active with several structurally related 1-O-phenylcarboxyl-β-D-glucoses; appreciable reaction rates, however, were observed only in the form ation of 1,6-di-O-protocatechuoyl-β-D-glucose. This to date unknown ester, as well as its digalloyl analog, was synthesized using acyltransferase immobilized on phenyl-Sepharose, and characterized by UV and 1H NMR spectroscopy. In addition, the 1,2-di-O-β-D-glucose esters of benzoic and anisic acid were obtained in this investigation.
Properties of Purine Nucleoside Phosphorylase (PNP) of Mammalian and Bacterial Origin
Authors: Bzowska Agnieszka , Kulikowska Ewa , Shugar David
Published: August 2018

Purine nucleoside phosphorylase (PNP), from calf spleen, human erythrocytes and E. coli have been examined with regard to structural requirements of substrates and inhibitors. Kinetic parameters (Km, Vmax/Km) for a variety of N(1) and/or N(7)-methylated analogues of guanosine, inosine and adenosine have been evaluated for all three enzym es. The substrate and/or inhibitor properties of purine riboside, 1,6-dihydropurine riboside, some deazapurine nucleosides: 3-deaza- and 7-deazainosine, 1,3-dideazapurine riboside (ribobenzimidazole), and a variety of acyclonu cleosides, have been determined with mammalian and bacterial enzymes. Overall results indicate distinct similarities of kinetic properties and structural requirements of the two mammalian enzymes, although there are some differences as well. The N(1) and O6 of the purine ring are necessary for substrate-inhibitor activity and constitute a binding site for the mammalian (but not the bacterial) enzymes. Moreover, nucleosides lacking the N(3) undergo phosphorolysis and those lacking N(7) are inhibitors (but not substrates). Methylation of the ring N(7) leads to two overlapping effects: labilization of the glycosidic bond, and impediment to proton ation at this site by the enzyme, a postulated prerequisite for enzymatic phosphorolysis. It is proposed that a histidine interacts with N(1) as a don or and O6 as an acceptor. Alternatively N(1)−H and C(2)−NH2, may serve as donors for hydrogen bonds with a glutam ate residue.

The less specific E. coli enzyme phosphorolyses all purine ring modified nucleosides but 7-deazainosine which is only an inhibitor. On the other hand, the bacterial enzyme exhibits decreased activity towards N(7)-methylated nucleosides and lack of affinity for a majority of the tested acyclonu cleoside inhibitors of the mammalian enzymes. The foregoing results underline the fundamental differences between mammalian and bacterial enzymes, including variations in the binding sites for the purine ring.
Hydrophilic Interactions between Charged Amino Acids and the Effect of Ions on the Strength of Interaction
Authors: Cserháti Tibor , Szögyi Mária
Published: August 2018

The interaction between oppositely charged amino acids was studied by charge-transfer reversed- phase thin-layer chromatography. The dependence of the lipophilicity of Arg, Lys and Orn on the concentration of G lu , Asp, Gln and Asn in the eluent was considered to be related to the strength of interaction. The interaction of dibasic amino acids with Glu and Asp was stronger than with Gln and Asn. Mono- (Li+, Na+, K+, Rb+ and Cs+) and divalent (Mg2+ and Ca2+) cation s decreased the strength of interaction suggesting the electrostatic character of the interaction. Their inhibitory effect mainly depended on their concentration and to a lesser extent on the ion charge and hydrated ion radii. Stepwise regression analysis proved that the strength of interaction depends on the polarity parameters of amino acids and is independent of their chemical structure.
Effect of Different Cyclohexane-1,3-dione Derivatives on the de novo Fatty-Acid Biosynthesis in Isolated Oat Chloroplasts
Authors: Kobek K. , Lichtenthaler H. K.
Published: August 2018

In the test system of isolated oat chloroplasts various structurally different cyclohexane-1.3- dione derivatives were investigated for their inhibitory effect on de novo fatty-acid biosynthesis. Cycloxydim proved to be the most efficient inhibitor in the group of the tested cyclohexane-1,3-diones. The alkoxyimino side-chain appears to be essential for the herbicidal activity. Compounds with variations in other substituents of the cyclohexanedione structure were less inhibitory. The I50-values of most of the applied substances for a 50% inhibition of de novo fatty-acid biosynthesis were in the range of 0.15 μM to 100 μM . Some compounds, however, showed no inhibitory effect.
1,25-Dihydroxyvitamin D3 Affects the Synthesis, Phosphorylation and in vitro Calmodulin Binding of Myoblast Cytoskeletal Proteins
Authors: Brunner Alicia , Boland Ana R. de
Published: August 2018

Incubation of chick embryo myoblasts with 1,25-dihydroxyvitam in D3 [1,25(OH)2D3] (10-10 M , 24 h). markedly stimulated the incorporation of [3H]leucine into total cytoskeletal proteins and this effect was abolished when the sterol treatment was performed in the presence of cycloheximide or actinomycin D. 1,2 5 (OH)2D3 selectively stimulated the de novo synthesis of several proteins with apparent molecular masses (isoelectric points) of 220 kDa (6.1 and 9.7), 150 kDa (7.5), 110 kDa (7.2), 68 kDa (9.5, 7.5 and 4.5), 50 kDa (8.5), 44 kDa (6.3), 27 kDa (7.8) and 15 kDa (5.5). Labelling of proteins with [125I]calmodulin after their separation on SDS-polyacrylamide gels showed that 1,25(O H)2D3-dependent protein of 110 kDa is the major calmodulin-binding component of myoblasts cytoskeleton.

In addition , the sterol increased the phosphorylation of several cytoskeletal proteins including that of 110 and 15 kDa whose synthesis potentiates.
Rat Liver DNase I - Like Activity and Its Interaction with Actin
Authors: Malicka-Błaszkiewicz Maria
Published: August 2018

Monomeric G actin, total actin and the F :G actin ratio were determined in the rat liver cytosol and nucleoplasm by measuring the inhibition of standard crystalline DNase I. Actin was purified from rat liver nucleoplasm by Sephadex filtration. Accompanying the considera­ble amount of actin an endogenous DNase I like activity was found in rat liver cytosol and nucleoplasm. It was shown, that similarly to DNase I from bovine pancreas the liver DNase was inhibited by mammalian and avian skeletal muscle actin as well as by endogenous liver actin, as verified by electrophoresis of DNase containing extracts on polyacrylamide gels with incorporated DNA .
Differential in vitro Anti-HIV Activity of Natural Lignans
Authors: Schröder Heinz C , Merz Helmut , Steffen Renate , Müller Werner E. G. , Sarin Prem S. , Trumm Susanne , Schulz Jutta , Eich Eckart
Published: August 2018

Abstract Two naturally occurring lignanolides, isolated from the tropical climbing shrub Ipomoea cairica, (-)-arctigen in and (-)-trachelogen in , were found to inhibit strongly replication of human immunodeficiency virus type 1 (HIV-1; strain HTLV-III B) in vitro. At a concentration of 0.5 (μм , (-)-arctigenin and (-)-trachelogenin inhibited the expression of HIV-1 proteins p 17 and p24 by 80 -90 % and 60 -70 % , respectively. The reverse transcriptase activity in the cul­ture fluids was reduced by 80 -90 % when the cells (HTLV-III B/H 9) were cultivated in the presence of 0.5 μм (-)-arctigen in or 1 μм (-)-trachelogenin . At the same concentrations, the formation of syncytia in the HTLV-III B/H 9-Jurkat cell system was inhibited by the compounds by more than 80%. A series of other lignan type compounds displayed no anti-HIV activity. Studying the molecular mechanism of action of (-)-arctigenin and (-)-trachelogenin we found that both compounds are efficient inhibitors of the nuclear matrix-associated DNA topoisomerase II activity, particularly of the enzyme from HIV -1-infected cells. Our results suggest that both compounds prevent the increase of topoisomerase II activity, involved in virus replication, after infection of cells with HIV -1.
Membrane Conductance Changes Associated with the Response of Motion Sensitive Insect Visual Neurons
Authors: Gilbert Cole
Published: August 2018

Abstract Intracellular recordings and impedance measurements from directionally-selective visual interneurons of the lobula plate of flies show that during motion, transmembrane conductance increases during both depolarizing responses to preferred directions and hyperpolarizing re­sponses to anti-preferred directions. This provides direct evidence that these interneurons are postsynaptic to two separate populations of excitatory and inhibitory input elements.
Synthesis and Use of Radiolabelled Cyanoacrylate Probes of the Photosystem II Herbicide Binding Site
Authors: McFadden Helen G. , Phillips John N.
Published: August 2018

Cyanoacrylates are potent inhibitors of photosynthetic electron transport (PET) and are potentially useful probes of the photosystem II herbicide binding site. A series of cyanoacrylates was synthesized and the Hill inhibition activities evaluated in order to select compounds suita­ble for radioactive synthesis. A cyanoacrylate, 2-(2-nitrophenoxy)ethyl 3-benzylamino-2-cyano-2-pentenoate, was found to displace diuron from the photosystem II herbicide binding site. For this compound the dissociation constant of the inhibitor/binding site complex was found to be 2 × 10-8 M with an active site concentration of 2 nmol/mg chlorophyll. In a similar system the corresponding figures for diuron were 1.2 × 10-8 m and 1.3 nmol/mg chlorophyll. Photoaffinity labelling of 1% II thylakoid proteins with 2-(2-azidophenoxy)ethyl 3-[7-14C]-benzylamino-2-cyano-2-pentenoate showed weak binding in the 32 and 28 kD mass regions, consistent with binding to the D, peptide.
Excretion into the Culture Medium of a Bacillus ß-Glucanase after Overproduction in Escherichia coli
Authors: Riethdorf Sabine , Ulrich Andreas , Völker Uwe , Hecker Michael
Published: August 2018

The β-glucanase gene (bgl) from Bacillus amyloliquefaciens was expressed in E. coli CSH 55 under the control of the PR promoter of phage λ that is repressed by the thermosensitive repressor C1857. Production of β-glucanase was drastically stimulated by a temperature shift to 42 C. This overexpression of the bgl gene (about 20% of the total cellular protein) led to an almost complete excretion of the otherwise periplasmic protein into the extracellular medium, β-glucanase accounted for more than 50% of the extracellular proteins. Col E 1 related plasmid (pEG 1) are amplified in E. coli relA strains in response to an amino acid limitation leading to a 10-fold increase in the activity of plasmid encoded genes. In this work we intended to maximize the expression of the bgl gene by a concerted action of a plasmid amplification and temperature induction. Surprisingly we could not increase the β-glucanase production above the level reached by plasmid amplification or temperature in­duction alone. The reasons for this unexpected result will be discussed. Under all conditions tested the expression of the bgl gene was much lower in the E. coli rel A strain NF 162 than in E. coli CSH 55; the low β-glucanase production was accompanied by a reduced excretion rate of the enzyme.
The Effect of Phytohormones and Sucrose Supply on the Induction of Tryptophan Decarboxylase in Developing Embryos of Juglans regia L
Authors: Lachmann Kay Uwe , Grosse Wolfgang
Published: August 2018

The de novo synthesis of tryptophan decarboxylase (TDC) (EC 4.1.1.27) in cotyledons of Juglans regia L. was accelerated at an earlier stage of development by harvesting immature fruits. After a lag phase of 6 h TDC activity became detectable in isolated cotyledons and reached values of about 5 nkat · g FW-1 following a 24 h incubation in double-distilled water. The TDC synthesis was suppressed to about 20% by supplying the incubation medium with 2 to 6% sucrose. Phytohormones were also involved in the regulation of TDC synthesis. A highly sensitive reaction was observed with a 50% suppression resulting from an external supply of 1 x 10-8
M gibberellic acid (GA3). Abscisic acid (ABA) was much less effective, reaching a similar level of suppression only at an unphysiologically high concentration of about 6 x 10-5
M. ABA, however, became one order of magnitude more effective when supplied together with sucrose. In contrast to GA3 and ABA, an exogenous supply of indole-3-acetic acid (IAA) stimulated TDC synthesis significantly at a concentration of 1 x 10-7
M. From these in vitro studies and earlier measurements of internal ABA concentrations as well as incorporation of [3H]tryptophan into IAA. we hypothesize a regulatory effect of assimilate supply and phyto- hormones on TDC biosynthesis in developing embryos of walnut (Juglans regia L.).
Surface Structure and Chemical Composition of Leaf Waxes from Quercus robur L., Acer pseudoplatanus L. and Jug Ians regia L
Authors: Prasad R. B. N. , Gülz Paul-Gerhard
Published: August 2018

The leaves of three deciduous broadleaf trees namely Quercus rohur L. (oak), Acer pseudo- platanus L. (maple) and Juglans regia L. (walnut) have different wax surface structures with different chemical compositions. On both the upper and lower side of the oak leaf, crystalloid platelets with sharp fringed edges were observed. Maple and walnut leaf surfaces showed quite different crystalloid arrangements on the upper and the lower side of the leaves. On the lower side of the maple leaf crystalloid platelets in form of lumps were found, whereas the upper side showed no crystalloids. Walnut leaves exhibited dense platelets with rounded edges on the upper side but not on the lower side.