bluuebunny/crossref_metadata_2025 huggingface dataset:
Molecular Modelling of the Interaction of Cyanoacrylate Inhibitors with Photosystem II Part 2. The Effect of Stereochemistry of Inhibitor Binding
Authors: Mackay Simon P. , O’Malley Patrick J.
Published: August 2018

The 2-cyanoacrylate inhibitors are a potent class of herbicides which block electron transfer in photosystem II. The spatial arrangement of different functional groups are an important factor in determining activity and a number of derivatives have been used as stereospecific probes of the secondary quinone binding site. More than one region of stereoselectivity in the binding site has been identified which influences the interaction with specific groups of the inhibitor. We have studied the interaction of various stereoisomers of the cyanoacrylates with the binding site in the D1 protein (residues Leu 210 to Val 280) by determining the nonbonded intermolecular energies between the modelled structures calculated by van der Waals and electrostatic interactions after energy minimization of the combined structures to reduce inter and intramolecular strain and have found that the results reflect the experimentally determined data
Complete Sequence of One Copy of the psbA Gene from the Thermophilic Cyanobacterium Synechococcus elongatus
Authors: Kloos Ralf , Stevens Edward , Oettmeier Walter
Published: August 2018

One copy of the psbA. gene which codes for the photosystem II reaction center D-1 protein from the thermophilic cyanobacterium Synechococcus elongatus has been sequenced. It is feas­ible that a disulfide bridge between D-1 Cys212 and D-2 Cys2I2 is reponsible for the thermo­ stability of the photosystem II reaction center from Synechococcus elongatus.
Linear Free Energy Relationships for N(7)-Substituted Guanosines as Substrates of Calf Spleen Purine Nucleoside Phosphorylase. Possible Role of N(7)-Protonation as an Intermediary in Phosphorolysis
Authors: Bzowska Agnieszka , Kulikowska Ewa , Shugar David
Published: August 2018

Quantitative structure-activity relationships (QSAR) for a series of N(7)-substituted guanosines as substrates for calf spleen purine nucleoside phosphorylase (PNP) were developed, and compared with those for acid hydrolysis of these analogues. There is no correlation between the rates for enzymatic phosphorolysis and acid hydrolysis, indicating that for the enzymatic reaction labilization of the glycosidic bond is not the only, nor the predominant, effect of N(7)-substitution. Multiple regression analysis of the enzymatic process revealed that optimal substrate properties (minimal Michaelis constant) are associated with the Taft electronic constant equal zero and a substituent size, parametrized by the Taft steric constant, smaller than that for a methyl group. These results support the hypothesis of protonation of the N(7)-position of the base by the enzyme as a catalytic mechanism for calf spleen PNP.

Attention is drawn to the postulated similar mechanism of action of other purine N-glycosidases, including plant antiviral proteins which function as RNAN-glycosidases, and possibly some DNA N-glycosidases which function as repair enzymes
Isolation and Properties o f Trimethylamine N-Oxide/Dimethylsulfoxide Reductase from the Purple Bacterium Rhodospirillum rubrum
Authors: Sajitz Paul , Klemme Jobst-Heinrich , Koch Hans-Georg , Molitor Michael
Published: August 2018

Among 4 strains of the purple bacterium Rhodospirillum rubrum only one did not contain trimethylamine N-oxide/dimethylsulfoxide reductase and was unable to grow under anaerobic dark conditions in fructose media supplemented with trimethylamine N-oxide (TMAO) or dimethylsulfoxide (DMSO ). By growing the bacteria in media treated with charcoal or supplemented with tungstate (2 mM ), TM AO/DMSO reductase activity was lowered to about 10% of the value of the untreated control. The enzyme was purified from the periplasmic protein fraction of strain S1 and was shown to contain 2 subunits (mol. wt. of 40,000 and 36,000, respectively) in a 1:1 stoichiometry. Although the affinity of the reductase to DMSO (Km - 0.67 mM) was much higher than to TMAO (Km = 24 m M ) , the catalytic activity with the latter substrate was about 10 times as high (90-110 μmol/min X mg protein) as with DMSO
Purification and Properties of Acridone Synthase from Cell Suspension Cultures of Ruta gvaveolens L.
Authors: Baumert Alfred , Maier Walter , Gröger Detlef , Deutzmann Rainer
Published: August 2018

Acridone synthase has been purified from cell suspension cultures of Ruta graveolens using a combination of gel filtration and ion exchange chromatography. The purified enzyme has an apparent molecular weight of 69 kDa on gel filtration and a subunit structure on SDS-PAGE of 40 kDa. The apparent Km-values are 10.64 μM and 32.8 μM for N-methylanthraniloyl-CoA and malonyl-CoA, respectively. Tryptic digestion of the homogeneous acridone synthase was performed. Seven of the peptides were chosen for microsequencing. The homology of the amino acid sequences from this particular polypeptide and corresponding peptides from chalcone synthase 3 from garden pea amounted to 76%.
Evidence for Nucleosomal Phasing and a Novel Protein Specifically Binding to Cucumber Satellite DNA
Authors: Fischer Thilo C. , Groner Sabine , Zentgraf Ulrike , Hemleben Vera
Published: August 2018

The nucleosomal organization and the protein-binding capability of highly repeated and methylated satellite DNA of cucumber (Cucumis sativus L.), comprising approx. 30% of the genome, were analyzed. Nucleosomal core DNA from satellite type I was prepared after micrococcal nuclease digestion of chromatin and sequenced. Most of the core sequences obtained could be grouped in two main (A and B) and two minor groups (C and D) indicating a specific and complex phasing of nucleosomes on this satellite DNA. In vitro, gel retardation assays with cloned satellite DNA repeats (types I-IV) demonstrated a specific binding of nuclear proteins. These specific binding effects are also obtained with genomic, in vivo methylated and sequence heterogeneous (1 to 10% diversity) satellite type I DNA. For the first time in plants, a satellite DNA-binding protein with an apparent molecular weight of 14 kDa (SAT 14) was identified.
Isolation and Partial Characterization of a Manganese and Chloride Binding Protein Present in Highly Purified Photosystem II Complexes of the Thermophilic Cyanobacterium Synechococcus sp.: The Protein Being Detected by Its L -Arginine Metabolizing Activity
Authors: Ruff Mathias , Pistorius Elfriede K.
Published: August 2018

Photosystem II complexes were solubilized with the detergent sulfobetaine 12 from thylakoid membranes of the thermophilic cyanobacterium Synechococcus sp. and purified by two sucrose gradient centrifugations and by chromatography on a Mono Q column. In such photosystem II complexes having a photosynthetic O2, evolving activity of 2938 μmol O2 evolved/mg chlorophyll x h, an ʟ-arginine metabolizing activity leading to ornithine and urea as major products, could be shown to be present. Besides ornithine and urea, a product (or products) of yet unknown structure is formed in addition - especially under aerobic conditions. This activity remained associated with photosystem II complexes even after substantial additional treatments to remove loosely bound proteins. On chlorophyll basis the maximal activity obtained under optimal assay conditions corresponded to 94 μmol ornithine formed/mg chlorophyll x h. This PS II associated, ʟ-arginine metabolizing enzyme was isolated (utilizing a manganese charged chelating Sepharose 6 B column) and partially characterized. It could be shown that this enzyme requires manganese and chloride for its ʟ-arginine metabolizing activity and that manganese becomes totally lost during purification indicating that manganese is bound to a fairly exposed site on the protein. Since it is rather unlikely that two different manganese and chloride binding proteins are present in such highly purified photosystem II complexes, the possibility of this protein being the water oxidizing enzyme will be discussed. Whether the manganese and chloride requiring ʟ-arginine metabolizing activity of this protein which provided a suitable assay for its isolation from photosystem II complexes, has any physiological significance, can not be answered at the present time.
Phosphatidylglycerol and ß-Carotene Bound onto the D 1-Core Peptide of Photosystem II in the Filamentous Cyanobacterium
Authors: Kruse O. , Radunz A. , Schmid G. H.
Published: August 2018

Photosystem II-particles from the cyanobacterium Oscillatoria chalybea were isolated by fractionating centrifugation. Purification of these particles was achieved by a 22 hours centrifugation over a linear sucrose density gradient at 217.500xg. The obtained particle fraction exhibited an oxygen evolution activity which corresponded to three times the rate of intact cells and to five times the rate of intact thylakoids. The chlorophyll protein ratio was 1:10 and the ratio manganese/chlorophyll 1:34.

SDS-polyacrylamide gel electrophoresis showed that the photosystem Il-fraction is composed of the core peptides D1 and D2, the chlorophyll-binding peptides CP 43 and CP 47, the extrinsic 33 kDa peptide (manganese stabilizing peptide, MSP) and phycobiliproteins with molecular masses between 16 to 20 kDa. Cyt b559 was not detected in our gel electrophoresis assay. Part of the peptides of the 30 kDa-region (D1, D2, MSP) occurred as aggregates with a molecular mass of 60 to 66 kDa.

The D 1-peptide was isolated from the PS Il-preparation by SDS-gel electrophoresis. The intrinisic peptide reacts in the Western blot procedure with the antiserum to phosphatidylglycerol and with the antiserum to β-carotene. Incubation of the peptide with the antisera to monogalactosyldiglyceride, sulfoquinovosyldiglyceride and zeaxanthine resulted negatively. The binding of phosphatidylglycerol onto the D 1-peptide was confirmed by lipid analysis in HPLC and fatty acid analysis by gas chromatography. Only this lipid, respectively the typical fatty acid mixture of this lipid was detected. The lipid is characterized by the fact that the hexadecenoic acid does not exhibit trans-configuration, as is true for phosphatidylglycerol of higher plants and algae, but occurs in cis-configuration.

With the antibody being directed towards the glycerol-phosphate residue and not towards the fatty acids, it can be concluded from the reaction of the antibodies with the bound lipid that the lipid is bound to the peptide via the fatty acid. The negatively charged phosphatidylglycerol increases the hydrophobicity of the peptide and leads to a negatively charged surface favouring binding of cations like calcium and magnesium. The fact that incubation of this PS Il-fraction with phospholipase inhibits photosynthetic activity by 25% which can be fully restored by addition of phosphatidylglycerol, shows that bound phosphatidylglycerol has a functional role.
Optical Multichannel Analysis of Protochlorophyllide Phototransformation in Detergent-Solubilized Etioplast Membranes of Wheat
Authors: Franck Fabrice , Ouazzani Mohammed Aziz , Dujardin Esther , Popovic Radovan
Published: August 2018

Extracts of wheat etioplast membranes obtained after treatment with 7 mᴍ n-octyl-β-ᴅ-glucopyranoside (OG), n-dodecyl-β-ᴅ-maltoside (DM) or Triton X-100 contained the three spectral forms of Pchlide (the photoactive Pchlide638 and Pchlide650 and the inactive Pchlide630) in various relative amounts . The OG extract had a Pchlide composition close to that of the intact membranes whereas the DM extract was enriched in Pchlide638 and the Triton extract was enriched in Pchlide630. Measurements of the kinetics of phototransformation and of timeresolved absorbance spectra during phototransformation in continuous light shows that the inactive Pchlide630 is in fact slowly transformed to Chlide, especially in the Triton extract where this form is more abundant. Addition of NADPH favours the phototransformation of Pchlide630 and the slow regeneration of Pchlide638 and Pchlide650 from Pchlide630 in darkness after illumination. No such regeneration was however observed in the Triton extract. NADPH had only slight effects on the Chlide shift towards shorter wavelengths after phototransformation in solubilized membranes.
Xanthanolides of Xanthium italicum Moretti and Their Biological Activity
Authors: Tsankova Elena T. , Trendafilova Antoaneta B. , Kujumgiev Athanas I. , Galabov Angel S. , Robeva Pepa R.
Published: August 2018

Seven xanthanolides were identified in the extract of X. italicum leaves. Antibacterial and cytotoxic activities were found for the total extract and its major constituents xanthinin and xanthatin.
A Novel Halogenated Compound Possessing Antibiotic and Cytotoxic Activities Isolated from the Fungus Resinicium pinicola (J. Erikss.) Erikss. & Hjortst
Authors: Becker Uta , Anke Timm , Sterner Olov
Published: August 2018

Pinicoloform, a novel unbranched acyclic compound containing a trichloromethyl group, has been isolated from extracts of the mycelia of the Basidiomycete Resinicium pinicola. It was isolated because of its ability to induce morphological and physiological differentiation of mammalian cells, although it also exhibits antibiotic and cytotoxic activities. The structure of pinicoloform was determined by spectroscopic methods.
Photoautotrophic Chenopodium rubrum Cell Suspension Cultures Resistant against Photosynthesis-Inhibiting Herbicides II. Physiological and Biochemical Properties
Authors: Thiemann Jutta , Barz Wolfgang
Published: August 2018

Eight photoautotrophic cell cultures of Chenopodium rubrum, which are resistant against the photosystem II inhibitor metribuzin, were characterized for their growth parameters, chlorophyll content and photosynthetic capacity. Herbicide resistance of the eight lines results from different mutations in the D 1 protein of photosystem II, which is the target for different photosystem II inhibitors. In the presence of 10-5 ᴍ metribuzin the eight lines showed substantial growth reduction depending on the degree of resistance, and this effect is explained by a reduced electron transport in photosystem II. The impaired photosynthetic capacity of the green cells in the presence of high metribuzin concentrations, leads to compensation effects similar to shade accommodation of plants. Adaptation includes an increase of the chlorophyll content, a decrease of the chlorophyll a/b ratios as well as an increase of thylakoid stacking and cell number per unit fresh weight. In the absence of the herbicide photosynthetic electron transport is not impaired, as indicated by measurements of electron transfer rates in photosystem II and flash-induced reduction kinetics of P-700+. In summary the alterations of the D 1 protein of the eight cell lines do not result in a reduced electron transport in photosystem II.
Free, Conjugated and Bound Polyamines during the Ceil Cycle in Synchronized Cultures of Scenedesmus obliquus
Authors: Kotzabasis Kiriakos , Senger Horst
Published: August 2018

The levels of free, conjugated and bound polyamines (PA) were analyzed during the cell cycle of the synchronized unicellular green alga Scenedesmus obliquus. The polyamines putrescine (PUT) and spermidine (SPD) in their free and conjugated forms accumulated per cell to a maximum in the cell cycle at about the 16 th hour after onset of illumination. The polyamines bound to macromolecules and membrane systems showed an additional peak around the 8-10 th hour of the cell cycle. The possible role of the different forms of polyamines in DNA replication, mitosis, cell division and development of the photosynthetic apparatus is discussed
c , T-Dependence of the Self Diffusion in Concentrated Aqueous Sucrose Solutions
Authors: Girlich D. , Lüdemann H.-D. , Buttersack C. , Buchholz K.
Published: August 2018

The self diffusion coefficients D of the water molecules and of sucrose have been determined by the pulsed field gradient NMR technique over a wide range of temperatures and concentrations (cmax: 70% w/w suc.). All temperature dependencies can be fitted to a Vogel- Tammann-Fulcher equation. The isothermic concentration dependence of D for the sucrose is given by a simple exponential concentration dependence
The Biflavonoid Pattern of Selaginella selaginoides
Authors: López-Sáez José Antonio , Pérez-Alonso María Jose , Negueruela Arturo Velasco
Published: August 2018

From Selaginella selaginoides the following three biflavonoids were isolated: amentoflavone, hinokiflavone and robustaflavone. The compounds were identified by means of spectroscopic methods
Reconstitution of an Allophycocyanin Trimer Complex Containing the C-Terminal 21-23 kDa Domain of the Core-Membrane Linker Polypeptide Lcm
Authors: Gottschalk Lothar , Lottspeich Friedrich , Scheer Hugo
Published: August 2018

Allophycocyanin (AP) was isolated from extracts of the cyanobacterium Mastigocladus laminosus. A fraction enriched in AP-associated polypeptides with apparent molecular masses of 21 -23 kD a in SDS-PAGE, was isolated on a preparative scale and identified as a homolo­gous mixture of C-terminal fragments of the core-membrane linker polypeptide Lcm. The complex (αAPβAP)3 ·21 -23 kD a was reconstituted and characterized by sucrose density gradient ultracentrifugation, absorption, fluorescence emission and circular dichroism spectroscopy. The 21 -23 kD a polypeptides were found to induce spectral changes in AP similar to those induced by the small core linker polypeptide Lc
8.9. Possible functions of the complex in phycobilisomes are discussed.
Resonance Effect of Low-Intensity Millimeter Waves on the Chromatin Conformational State of Rat Thymocytes
Authors: Belyaev Igor Ya. , Kravchenko Vyacheslav G.
Published: August 2018

The method of anomalous viscosity time dependencies (AVTD) was modified for the study of the changes in the chromatin conformational state (CCS) of rat thymocytes of the Wistar line. The response of the thymocytes of male rats to low-intensity millimeter waves (MMW) was examined. It was shown that MMW at power densities (PD) of 1 μW/cm2 produced a resonance effect on the CCS in the frequency range of 41.56-41.67 GHz. The resonance fre­quency of the cell response did not vary significantly among five examined rats and was deter­ mined to be 41.61 ±0.01 GHz. A halfwidth of resonances was averaged to 40 MHz. The power dependence of the resonance effect was measured in the range of 10-11-10-4 W/cm2. Statistically significant changes in CCS were registered, starting with 10-9 /cm2. Right-and left-handed circularly polarized MMW were shown to differ in efficiency at the resonance fre­quency.

The established regularities in the thymocyte response to low-intensity MMW was very similar to those which have been previously found for E. coli cells.
The Effects of Externally Applied Lithium and Strontium on the Arsenazo-Monitored Cytosolic Calcium Signal of the Limulus Ventral Photoreceptor
Authors: Stieve Hennig , Rüsing Gabriele , Yuan Weijia , Hennig H. Thomas
Published: August 2018

The intracellular arsenazo signal indicating the transient light-evoked change in cytosolic Ca2+ (or Sr2+) concentration was measured in Limulus ventral photoreceptor simultaneously with the receptor potential at 15 °C. The decline of the arsenazo signal has two phases (D1 and D2) when the photoreceptor is bathed in physiological saline.

1. When calcium is replaced by strontium in the superfusate both receptor potential and arsenazo signal are markedly increased in amplitude and the membrane potential is hyper­ polarized. The decline of the arsenazo signal is prolonged and becomes monophasic; the fast phase D1 of the decline disappears.

2. In strontium saline under voltage clamp conditions the slope of the monophasic decline of the arsenazo signal is the steeper the more negative the membrane voltage.

3. After replacing sodium by lithium in the superfusate the rise of the receptor potential and of the arsenazo signal are not much altered. The decline of the arsenazo signal, however, is slowed down more than 3-fold; this is due to the complete suppression of the fast phase D1 and the retardation of the slow phase D2 of the calcium re-decline.

Interpretation:

1. The Na-C a exchanger can accept strontium as a calcium substitute. Strontium has a weaker desensitizing action than calcium. Strontium is not-or only very little -taken up by the endoplasmic cisternae.

2. In sodium-free lithium saline the Na-C a exchanger, the Na-K ATPase and the calcium uptake system of the endoplasmic cisternae do not function. Therefore the intracellular calcium level rises.
Inhibition of Maize (Zea mays L.) Root Plasma Membrane-Bound Redox Activities by Coumarins
Authors: Lüthje Sabine , Gonzaléz-Reyes José A. , Navas Placido , Döring Olaf , Böttger Michael
Published: August 2018

Modulation of plasma membrane-bound NADH:hexacyanoferrate III oxidoreductase activities by dicumarol and warfarin was investigated with plasma membrane vesicles of Zea mays L. (cv. Sil Anjou 18) roots, prepared by aqueous two phase partitioning. Vesicles were about 65% right-side out orientated as demonstrated by enzyme latency of vanadate sensitive ATPase activity. Dicumarol or warfarin, respectively, inhibited NADH:hexacyanoferrate III oxidoreductase activity in a concentration-dependent manner and inhibition could be reversed partially by addition of quinones
Theoretical Studies on Molecular Determinants for Recognition at H3 Histamine Receptors
Authors: Mazurek Aleksander P. , Karpińska Grażyna
Published: August 2018

The determinants for recognition at H3 histamine receptors are considered. Findings based on quantum-chemical calculations suggest that H3 histamine receptor is less hydrophilic than the H2. The form most likely to be recognized by the H3 receptor is an intramolecularly hydrogen-bonded form of α-methylhistamine. Receptor environment and hydration effects of active form of histamine analogs are of crucial importance
Pheromonal Production of and Response to Optically Active Epoxydienes in Some Geometrid Moths (Lepidoptera: Geometridae)
Authors: Tóth M. , Szőcs G. , Francke W. , Schmidt F. , Philipp P. , Löfstedt C. , Hansson B. S. , Farag A. I.
Published: August 2018

In pheromone extracts of calling female Chiasma clathrata L. (Lepidoptera: Geometridae), a defoliator pest of alfalfa, (Z,Z,Z)-3,6,9-heptadecatriene and (Z,Z)-6,9-cis-3,4-epoxyheptadecadiene was identified. Chiral gas chromatography using a modified cyclodextrin and synthetic reference samples proved the natural epoxide to show (3R, 4S)-configuration. In field trapping tests, only the pure (3R, 4S)-enantiom er of the epoxide attracted males. The addition of the triene component was synergistic. Males of the sympatric species Tephrina arenacearia Hbn. (Lepidoptera: Geometridae) were caught only in traps with baits containing the (3S, 4R)-enantiomer [together with a previously described minor component, (Z,Z)-3,9-cis- 6,7-epoxyheptadecadiene]. In trapping tests conducted in a different biotope, Abraxas grossulariata L. (Lepidoptera: Geometridae) males were attracted by the (3S, 4R)-enantiomer, whereas the (3R, 4S)-enantiomer attracted a close relative, Abraxas sylvata Scop. (Lepidoptera: Geometridae). The present results suggest that one of the key mechanisms responsible for pheromone specificity among both the two alfalfa geometrids and the two A braxas species in their respective biotops, may be the use of different enantiomers of the same polyenederived epoxide as a sex pheromone component. It is probable that this discrimination mechanism is widespread among moth species utilizing epoxide pheromone components
β-Carboline Alkaloids from Ribes nigrum L.
Authors: Blech St. , Budzikiewicz H.
Published: August 2018

From Ribes nigrum L. two β-carboline alkaloids (deshydroxymethyl flazin (1) and flazin methyl ether (2)) could be isolated in minute amounts. The structure elucidation is described. The two compounds are present in the freshly pressed juice, but they are also formed during storage of the juice by condensation of tryptophane with ascorbic acid or its degradation products. This could be shown by adding 14C-labelled ascorbic acid to the juice. After four weeks’ incubation radioactive 1 and 2 could be isolated.
On the Mechanism of Metabolic Reactions of Amino Acids Catalyzed by Vitamin B6 and Related Aldehydes
Authors: Sivý J. , Kettmann V. , Krätsmár-Šmogrovič J.
Published: August 2018

The crystal structure of [(N-salicylidene-ᴅ,ʟ-glutamato)(pyridine)]copper(II), a model for vitamin B6-amino acid-related metal complexes, has been determined by an X-ray analysis. A close examination of the structural data on this and other related complexes combined with quantum-chemical (INDO/2) calculations enabled us to make a clear distinction between two mechanisms proposed earlier for metabolic reactions of amino acids catalyzed by the vitamin B6 (or salicylaldehyde)-metal system. The results are consistent with a transient formation of a carbinolamine species resulting from the addition of a solvent water or alcohol molecule to the Schiff base double bond, thus supporting the mechanism of the catalysis as proposed by Gillard and Wootton.
Light-Harvesting Complexes of Aerobic Bacteriochlorophyll-Containing Bacteria Roseococcus thiosulfatophilus, RB3 and Erythromicrobium ramosum, E5 and the Transfer of Excitation Energy from Carotenoids to Bacteriochlorophyll
Authors: Yurkov Vladimir , Gad’on Nasser , Angerhofer Alexander , Drews Gerhart
Published: August 2018

The spectral analysis of membrane fractions and a fraction enriched in light-harvesting (LH) complex I + reaction center (RC) of Roseococcus thiosulfatophilus, RB3 and of the membrane fraction and of the isolated LH II and LH I + RC complexes of Erythromicrobium

ramosum, E5 is reported. Quantum yields of singlet energy transfer between carotenoids and bacteriochlorophyll (light-harvesting function) were calculated from comparison of absorption and fluorescence excitation spectra of the respective preparations. The results indicate that the excess of carotenoids in the membrane does not contribute to the lightharvesting function of the LH complexes.
A Survey of Phytoalexin Induction in Leaves of the Rosaceae by Copper Ions
Authors: Kokubun Tetsuo , Harborne Jeffrey B.
Published: August 2018

The leaves of 130 species of Rosaceae were surveyed for phytoalexin induction. Both biotic and abiotic induction was examined and antifungal compounds were detected in 47 species. However, these compounds appeared to be constitutive metabolites, released from bound phenolic materials already present in the leaf. In Pyrus, hydroquinone was produced from the hydrolysis of arbutin present in the vacuole before inoculation. In most other species, the fungitoxic agents were mainly catechin-like derivatives, apparently released from the tannins present within the leaf. By contrast, the synthesis in the leaf of the characteristic biphenyl or benzofuran phytoalexins which are produced in sapwood, was confined to a very few species. The biphenyl aucuparin was identified as a phytoalexin from the leaves of Sorbus aucuparia.
Modulation of Cell-Mediated Immunity by Lithium Chloride
Authors: Kubera M. , Bubak-Satora M. , Holan V. , Krol W. , Basta-Kaim A. , Roman A. , Skowron-Cendrzak A. , Shanid J.
Published: August 2018

Immunomodulation of cell-mediated immunity was studied in mice treated with either lithium chloride (LiCl), anti-CD 8 monoclonal antibody or their combination. While 6-day LiCl treatment decreased the ability of their splenocytes to induce a local graft-versus-host reaction -anti-CD 8 abolished this effect. The proliferative response of spleen cells from those three groups of mice to concanavalin A stimulation in vitro was significantly increased. The natural killer (NK) cell toxicity of the mice was decreased by over 43% after the 6-day LiCl treatment, but was ×2.5 higher then the control value after a longer 21-d treatment. These results indicate that the immunomodulatory capacity of lithium is dependent on the type of cell population studied, and on the schedule of administration.
External Flavonoids of Ocotillo (Fouquieria splendens)
Authors: Wollenweber Eckhard , Yatskievych George
Published: August 2018

Leaves and stems of Fouquieria splendens were found to accumulate flavonoid aglycones on their surfaces. Three flavones and five flavonols have been identified.
Stereospecific Reduction of /R(+)-Thioctic Acid by Porcine Heart Lipoamide Dehydrogenase/Diaphorase
Authors: Schempp H. , Ulrich H. , Elstner E. F.
Published: August 2018

R(+)-thioctic acid is the naturally occurring cofactor in α-ketoacid dehydrogenases. We show both photo­ metrically by NADH + H+ oxidation and by HPLC prod­uct analysis that this enantiomer is rapidly reduced by NADH + H+ catalyzed by porcine heart lipoamide dehydrogenase/diaphorase. The racemate exhibits approxi­ mately 40% activity as compared to the R (+) form while the S (-) enantiomer photometrically shows little activity and yields no detectable reduced lipoic acid.
Arom atic Amino Acid and Amine Levels in the Hemolymph of Parasitized and Unparasitized Larvae of Mythimna separata
Authors: Shimizu T. , Takeda N.
Published: August 2018

The levels of aromatic amino acids and amines in the hemolymph of larvae of the common armyworm, My­ thimna separata, were analyzed after parasitization by the braconid wasp, Apanteles kariyai. Methyldopa, homovanillic acid, tryptophan and tyrosine remained unchanged in unparasitized and parasitized larvae. Dopamine and DOPA showed characteristic changes at pupation that were associated with the hardening and darkening of the cuticle; Dopamine in the hemolymph of unparasitized last instar larvae increased before pu­pation. Large increases in kynurenine and octopamine were detected in parasitized larvae. The increased level of octopamine in the hemolymph may be stress related.
Ribonucleosides in Human Milk. Concentration Profiles of These Minor Constituents as a Function of the Nursing Time
Authors: Schlimme Eckhard , Schneehagen Kirsten
Published: August 2018

Ribonucleosides are secreted as products of cellular RNA and ribonucleotide metabolism into physiological fluids such as blood, milk and urine. Unmodified and modified ribonucleo­sides have been detected in the micromolar range as minor constituents in the milk of differ­ent mammals. In addition to the common nucleosides adenosine, cytidine, guanosine, inosine and uridine, modified components such as 1-methyladenosine, 1-methylguanosine, 1-methylinosine, N2-methylguanosine, N2-dimethylguanosine, N6-carbamoyl-ʟ-threonyladenosine, pseudouridine and 5-aminoimidazole-4-carboxamide-N-ribofuranoside (AICAR) have been identified and most of them quantified in samples of human and/or bovine and/or goat’s milk. From these investigations it is known that nucleosides, in analogy to nucleotides, show a typical species-specific pattern. Longitudinal studies have been carried out to determine the concentration profiles of the individual ribonucleosides in the milk of humans as a function of the nursing time.
Dendryol A, B, C, and D, Four New Compounds Produced by a Weed Pathogenic Fungus Dendryphiella sp.
Authors: Tanaka Masayasu , Ohra Junko , Tsujtno Yasuko , Fujimori Takane , Ago Hideo , Tsuge Hideaki
Published: August 2018

Four novel anthraquinone derivatives, named Dendryol A, B, C, and D, were isolated from the culture filtrate of Dendryphiella sp. Their structures were elucidated from spectral data and single-crystal X-ray diffraction analysis. The four compounds showed phytotoxic activity against barnyardgrass at more than 1 μl application of 5000 μg/ml.
Induction of Secondary Metabolism by Environmental Pollutants: Metabolization of Pyrene and Formation of 6,8-Dihydroxy-3- methylisocoumarin by Crinipellis stipitaria JK 364
Authors: Lange Bettina , Kremer Stefan , Sterner Olov , Anke Heidrun
Published: August 2018

In submerged cultures, when grown in the presence of pyrene. the saprophytic and plant inhabiting basidiomycete Crinipellis stipitaria was found to produce 6,8-dihydroxy-3-methyl-isocoumarin. The amount of 6,8-dihydroxy-3-methylisocoumarin formed depended on the concentration of pyrene in the medium. In cultures incubated without pyrene or with less than 2.5 mg/l no formation of 6,8-dihydroxy-3-methylisocoumarin was observed. Besides pyrene, chrysene, another four ring polycyclic aromatic hydrocarbon, induced isocoumarin formation whereas anthracene, phenanthrene or fluoranthene were not effective. During metabolization experiments with [4,5,9,10-14C]pyrene (0.4 mCi (14.8 kBq)/mmol), labelled 6.8-dihydroxy-3-methylisocoumarin (specific activity 15 μCi (0.6 kBq)/mmol) was isolated, in addition labelled acetic acid (specific activity 0.1 μCi (4 Bq)/mmol) was identified. When C. stipitaria JK 364 was incubated for 14 days with 5 μCi (0.2 kBq) sodium [2-14C]acetate and 10 mg/l pyrene. labelled 6.8-dihydroxy-3-methylisocoumarin was isolated from the culture. The results are in agreement with the polyketide origin of the isocoumarin and proof the breakdown of pyrene to acetate which is a central intermediate in the pathway from pyrene to 6,8-dihydroxy-3-methylisocoumarin.
Interaction of Organophosphorus Insecticide Methylparathion with Calf Thymus DNA and a Synthetic DNA Duplex
Authors: Blasiak Janusz , Kleinwächter Vladimír , Walter Zofia , Žaludová Renata
Published: August 2018

The interaction of an organophosphorus insecticide methylparathion (O.O-dimethyl 0-4-nitrophenyl phosphorothioate) with double-stranded DNA was characterized by UV and circular dichroism (CD) spectroscopy. Two kinds of DNA were employed: calf thymus DNA (CT DNA) and a synthetic two-stranded oligomer of sequence 5′-d(TTGGATCCGAATT-CAAGCTT)-3′ Melting curves and CD spectra were taken for the DNAs in the presence of the insecticide at methylparathion/DNA base pair molar ratio of 0.5. The insecticide evoked a decrease of the melting temperature and a broadening of the transition range for CT DNA. Similar effects were observed for the synthetic oligomer but they were less pronounced than in the case of CT DNA. Methylparathion evoked a slight shift and an increase in the amplitude of the negative band in the CD spectra of both DNAs. Obtained results indicate that methylparathion may perturb the thermal stability and conformation of DNA, which is an evidence that the insecticide has an ability to interact directly with DNA.
Involvement of Oxidative Burst in Isoflavonoid Metabolism in Elicited Cell Suspension Cultures of Pueraria lobata
Authors: Park Hyung-Hwan , Hakamatsuka Takashi , Sankawa Ushio , Ebizuka Yutaka
Published: August 2018

Hydrogenperoxide exogenously administerd to the suspension-cultured cells of Pueraria lobata stimulated a rapid disappearance of the constitutive isoflavonoids (malonylglucosides of daidzein and genistein) from the methanol soluble fraction of the cells, in a similar manner as observed in the cells treated with yeast extract or glycoprotein preparation of Phyto­phthora megasperma f. sp. glycinea. Rapid generation of H2O2 was detected within 10 min after elicitation at the cell surface, presumably preceded by the activation of plasma membrane NAD(P)H-oxidases. Pretreatment of some representative NAD(P)H-oxidase inhibitors such as SHAM, DEDTC and KCN (1 mᴍ each) to the cells 1 h before elicitation resulted in almost complete inhibition of the elicitor-stimulated metabolism of isoflavonoids for 4 h, whereas treatment of the inhibitors at 1 h after elicitation showed no significant effect on the rapid isoflavonoid metabolism. These findings suggest that this type of response to elicitation could be regarded as a plausible initial defense strategy prior to the appearance of de novo synthesized defensive barriers such as phytoalexins and lignin in plant-pathogen interaction.
The Effect of Weak Permanent Magnetic Fields on the Electric Properties of Lipid-Bilayers
Authors: Pazur Alexander
Published: August 2018

Black lipid membranes were prepared on a Teflon septum separating electrically the two chambers of a Teflon cuvette, using the technique of Mueller et al., (Nature 194. 979 (1962)). An external, static magnetic field was applied, whose intensity varied from 0 G to 100 G at the membrane location. Field applications higher than 10 G are effecting higher leakage currents, increased capacity and faster breakdown of the bilayer state, as compared to the absence of a magnetic field. If bilayers were doped with chlorophyll a, these effects were increased. Quantum mechanical and thermodynamical phenomena on membranes will be discussed as possible origins of these effects.
Protective Effect of Amphiphilic Ammonium Salts on the Oxidation of Lecithin Liposomes
Authors: Gabrielska J , Kleszczyriska H , Przestalski S
Published: August 2018

The inhibition effect of selected amphiphilic quaternary alkyl-substituted ammonium salts on oxidation of the lecithin liposome membrane was studied, induced by ultraviolet light and Fe2+ ions with ascorbic acid added. The salts differed in alkyl chain length Ri having the following alkyl substitutents: R1 = C9H19; R2 = C10H21; R3 = C12H25; R4 = CH2OC14H29; R5 = CH2OC16H33.

It was found that all the salts used induced inhibition in oxidation of the liposome membrane, both that induced by UV light and ferrous ions. The antioxidant activity of the salts studied, dependent on the chain length and concentration, can be represented by the relation R1 < R2< R3 < R4 < R5. A similar dependence was obtained when the hemolytic activity

of compounds was studied. Activity of salts increase with alkyl chain length.
Notes: The Biflavonoid Pattern of the Moss Bartramia mossmanniana (Bartramiaceae, Musci)
Authors: López-Sáez José Antonio , Pérez-Alonso María José , Velasco-Negueruela Arturo
Published: August 2018

From Bartramia mossmanniana the following five biflavonoids were isolated: bartramiaflavone, anhydrobartramiaflavone, philonotisflavone, 2,3-dihydrophilonotisflavone and 5′,3‴-dihydroxyamentoflavone.
Notes: Flavonols from Cryptocarya alba
Authors: Timmermann Barbara N , Valcic Susanne , Liu Yong-Long , Montenegro Gloria
Published: August 2018

Ten flavonoids and chlorogenic acid were isolated from the leaves and stems of Cryptocarya alba (Lauraceae). The flavonoids were identified as isorhamnetin. kaempferol, quercetin and their glycosides isorhamnetin-3-O-rhamnoside, isorhamnetin-3-O-galactoside, isorhamnetin-3-O-glucoside, kaempferol-3-O-galactoside, quercetin-3-O-rhamnoside (quercitrin), quercetin-3-O- galactoside (hyperoside), and quercetin-3-O-glucoside (isoquercitrin).
Involvement of Thiol Groups in Blue-Light-Induced Phosphorylation of a Plasma Membrane-Associated Protein from Coleoptile Tips of Tea mays L.
Authors: Rüdiger Wolfhart , Briggs Winslow R.
Published: August 2018

Light-induced phosphorylation of a 114 kDa protein in plasma membranes isolated from the tips of maize coleoptiles was investigated in the presence of several thiol reagents at the concentration of 1 mᴍ. Dark phosphorylation of the protein was not affected but lightinduced phosphorylation was inhibited 50% with iodoacetamide, 75% with N-ethylmaleimide and 93% with N-phenylmaleimide. Previous incubation of the inhibitors with mercaptoethanol abolished the inhibitory activity completely. N-phenyl-maleimide showed the same inhibition whether it was applied before or after irradiation of the sample. Involvement of thiol group(s) in processes after photoexcitation is discussed.
Further Characterization of Aspartate Aminotransferase from Haloferax mediterranei: Pyridoxal Phosphate as Coenzyme and Inhibitor
Authors: García-Muriana Francisco J. , Alvarez-Ossorioa María C. , Sánchez-Garcés María M. , Rosa F. de la , Relimpio Angel M.
Published: August 2018

The enzyme aspartate aminotransferase has been isolated from the halophilic bacterium Haloferax mediterranei in its apoenzyme form. The interaction with its coenzyme (pyridoxal phosphate) has been investigated. For concentrations up to 0.05 mᴍ, the incubation with pyridoxal phosphate reconstituted the active complex (holoenzyme) following a second order kinetic with a k2 of 5.2 min-1mᴍ-1. This active complex showed a dissociation constant (Kd) of 7.8 x 10-6 ᴍ. For concentrations higher than 0.1 mᴍ, pyridoxal phosphate produced an inactivation process with a complex second order kinetic. This inactivation is partially reverted by dialysis or by lysine treatment. Thus, after 80% of inactivation, 55% of the original activity is recovered by a long-time dialysis, and with 50 mᴍ lysine also a partial reactivation (among 20-33%) is observed. The enzyme treated with 1 mᴍ pyridoxal phosphate has a different behavior in Sepharose chromatography indicating that the modified enzyme presents a smaller size due to a conformational change.
Plant Disease Resistance Inducing Activity of 7-Oxo- and 7-Hydroxysterols
Authors: Schabdach H. , Johne S. , Steiner U. , Seifert K.
Published: August 2018

The 7-oxosterols 1-2 and the 7-hydroxysterols 3-6 induce resistance toward the fungal pathogens Puccinia striiformis West, and Puccinia hordei Otth in barley and wheat. Primary leaves of the plants were sprayed with solutions of the compounds ( 10-4 mol/l in 1% aqu. ethanol) followed, 2 days later, by challenge inoculation with the fungal pathogens. The results indicate that 7α- and 7β-hydroxylated epimers of β-sitosterol and cholesterol show the highest value of induced resistance (39-49% reduction of infection sites). No enhanced resistance toward the fungi Erysiphe graminis DC f.sp. tricitic and hordei and Cochliobolus sativus Ito & Kuribayashi was observed.
The Mesenchyme-Like Layer of the Fiber Cells of Trichoplax adhaerens (Placozoa), a Syncytium
Authors: Buchholz Katja , Ruthmann August
Published: August 2018

The fiber cells of the middle layer of Trichoplax adhaerens are interconnected by slender extensions. Newly formed connections after mechanical disruption of the tissue studied in ultrathin sections revealed cytoplasmic continuity between the cell bodies, suggesting a syncytial organisation of the fiber cell layer. The slender extensions connecting the cell bodies are traversed by microtubules and microfilaments. The structure of rare osmiophilic cell contacts suggests a stage in the fusion of adjacent cell membranes.
Age Dependence of Murine Spermatogenesis
Authors: Hacker-Klom Ursula Beate
Published: August 2018

The dependence of spermatogenesis function on murine age shall be investigated. Thus, testicular samples of at least 10 NMRI mice per group aged 0 to 26 months are analysed by flow cytometry after staining the DNA with DAPI. The aim of this study is to be able to account for the influence of age on mice.

There are no changes in spermatogenesis in mice aged 11 weeks up to 16 months with respect to testis weight and to the frequency of different testicular cell types. From 16 months onwards, there is a tendency to a reduced spermatogenesis function; The frequency of round spermatids is decreased. In addition, there is an increased chromatin dispersion in elongated spermatids with age. Thus, older mice (>16 months) should not be used for experiments e.g. on radiation and drug effects any more. The frequency of abnormal diploid spermatozoa does not increase with age.
Limits of Natural Science: Brain Research and Computers
Authors: Stieve Hennig
Published: August 2018

The criterion that pure natural science can only investigate objective phenomena which can be observed by independent observers sets certain limits to our scientific understanding of brain functions. The methods and the present state of brain research and of computer development are described. The limitations of brain research are discussed by comparing the properties of brains and computers. At least for the time being we do not know of any natural scientific -i.e. physical or chemical -method which allows the objective measurement of consciousness, sensations, and emotions.
Pyoverdin, Ferribactin, Azotobactin -a New Triade of Siderophores from Pseudomonas chlororaphis ATCC 9446 and Its Relation to Pseudomonas fluorescens ATCC 13525
Authors: Hohlneicher U. , Hartmann R. , Taraz K. , Budzikiewicz H.
Published: August 2018

It is shown that Pseudomonas fluorescens ATCC 13525 and Pseudomonas chlororaphis ATCC 9446 produce identical pyoverdins and ferribactins. As the structures of these sidero­ phores are usually species or even strain specific this exception should be kept in mind in view of the reclassification of the genus Pseudomonas. From Pseudomonas chlororaphis an additional siderophore could be obtained which has the same peptide chain as the co-occur­ ring pyoverdins and ferribactin, but a chromophore which is typical for azotobactins from Azotobacter vinelandii.
Properties of a Dissimilatory Nitrate Reductase from the Halophilic Archaeon Haloferax volcanii
Authors: Bickel-Sandkötter Susanne , Ufer Martina
Published: August 2018

Grown under anaerobic conditions in presence of nitrate, Haloferax volcanii shows nitrate reduction and accumulation of nitrite in the culture medium. We found a membrane-associated nitrate reductase, which could easily be solubilized by gently stirring of isolated membranes. Surprisingly, this nitrate reductase requires no NaCl for its activity. A medium pH of 7.5 and high temperatures up to 80 °C are necessary for optimum activity. Kinetic studies showed that the apparent Kᴍ was 0.36 mmol/l for nitrate and 80 μmol/l for dithionite-reduced methyl viologen. The respiratory chain inhibitor cyanide effects nitrate reduction noncompe-titively with respect to nitrate with a Ki of 0.3 mmol/l. Azide was a strong inhibitor: The concentration required for half maximal inhibition was 60 μmol/l, whereas thiocyanate and chlorate were much weaker inhibitors. The isolated enzyme was partially purified by frac­tionated precipitation using polyethylene glycol. SDS gel electrophoresis resulted in three putative subunits of the nitrate reductase of molecular masses of about 100, 61, and 31 kDa.
The Role of Phosphatidylglycerol as a Functional Effector and Membrane Anchor of the D1-Core Peptide from Photosystem II-Particles of the Cyanobacterium Oscillatoria chalybea
Authors: Kruse O. , Schmid G. H.
Published: August 2018

The intrinsic polypeptide D1, isolated from photosystem (PS) Il-particles of the cyanobacterium Oscillatoria chalybea, was obtained by electroelution and fractionated extraction with organic solvents. Purification was demonstrated by Western blotting and amino acid sequenc­ing. By carrying out D1 -immunization in rabbits a polyclonal monospecific D1-antiserum was obtained.

For the qualitative characterization of D1 as a lipid-binding peptide, the effect of the lipids phosphatidylglycerol (PG), monogalactosyldiacylglyceride (MGDG) and phosphatidylcho­ line (PC) on PSII-oxygen evolution was analysed in reconstitution experiments. In these experiments purified photosystem II (PSII)-particle preparations were treated with the en­zyme phospholipase A2 and supplemented with lipid emulsions. We were able to show that the inhibition of electron transport, as the consequence of this lipase treatment, was only relieved, if phosphatidylglycerol was added to the preparation. A model was proposed, in which phosphatidylglycerol is a functional effector for the optimal conformation of D1 in the PSII core complex. Phosphatidylglycerol molecules are unusually tightly bound to the D1 peptide by hydrophobic interactions. A covalent binding seems not probable. The localisation of phosphatidylglycerol binding sites was found by trypsin treatment of D1 and analysis of the obtained oligopeptides with HPLC and immunoblotting. The binding sites could be confined to the hydrophobic amino acid section between arginine 27 and arginine 225, which is known to be the membrane anchor of D1. This has led us to the conclusion that the phospho­lipid phosphatidylglycerol plays an important role for anchoring the D1-peptide and for its orientation in the thylakoid membrane. Phosphatidylglycerol with its high amount of palmitic acid has in prokaryotic cyanobacteria apparently a role in stabilization and orientation.

The high turn-over of D1 and the spatial separation of the synthesis-and incorporation-site in the membrane, developed during evolution in eukaryotic organisms, might have changed the requirement on the mobility and the orientation of D1 in photosynthetic membranes.