bluuebunny/crossref_metadata_2025 huggingface dataset:
The Formation of Phosphate End Groups in the Radiolysis of Polynucleotides in Aqueous Solution
Authors: Murthy Cherla P. , Deeble David J. , Sonntag Clemens von
Published: August 2018

The polynucleotides poly(U), poly(C), poly(A) and poly(G) have been y-irradiated in N2O- and N2O/O2 (4:1)-saturated aqueous solutions. Hydroxyl radicals from the radiolysis of water react with the polynucleotides thereby producing among other lesions strand breaks. Strand breakage is connected with the formation of phosphomonoester end groups. Such end groups have been determined by measuring inorganic phosphate after a three hour incubation at 37 °C with acid or alkaline phosphatase.

In the absence of oxygen G(phosphomonoester end groups) (in units of μmol J-1) are 0.47 (poly(U)), 0.17 (poly(C)) and ≤ 0.04 (poly(A) and poly(G)). In the case of poly(U) and poly(C) on heating the sample for one hour at 95 °C prior to incubation with phosphatases the above values increased by 0.14 and 0.07 μmol J-1, resp., whereas such treatment of the purine polynucleotides still did not produce a measurable yield of phosphomonoester end groups. Comparing these values with G values for strand breakage taken from the literature, about two phosphomonoester end groups are formed per strand break in poly(U) while for poly(C) this ratio is about unity. The purine polynucleotides show very low yields of strand breakage in agreement with the negligible phosphomonoester yields.

In the presence of oxygen G(phosphomonoester end groups) are 0.46 (poly(U)), 0.21 (poly(C)), and ≤ 0.04 (poly(A) and poly(G)). On heating, these values increase, most markedly for poly(U) and poly(C). This is possibly linked to the decomposition of unstable hydroperoxides which are formed in high yields in poly(U) and poly(C) (G = 0.7 and 0.19 μmol J-1 resp.).

It is known that at least in the case of poly(U), base radicals attack a sugar moiety and are the main precursors of these lesions. G(phosphomonoester end groups) are considerably lower in the case of the purine polynucleotides. Whether this is due to an inability of the base radicals to attack a sugar moiety or has other reasons must remain an open question.
X-Ray Studies on Phospholipid Bilayers. VIII. Interactions with Chlorpromazine · HCl
Authors: Suwalsky M. , Gimenez L. , Saenger V. , Neira F.
Published: August 2018

Chlorpromazine is a widely used phenothiazine tranquilizer known to alter the shape of normal erythrocytes and their osmotic fragility. In order to understand the nature of the interactions chlorpromazine · HCl (CPZ · HCl) was made to interact with phospholipid bilayers formed by dimyristoylphosphatidylethanolamine (DMPE) and dimyristoylphosphatidylcholine (DMPC). This study was carried out by X-ray diffraction on crystalline powders of various molar mixtures of CPZ · HCl with DMPE and DMPC, with and without water. It was found that CPZ · HCl significatively affects the bilayer structure of DMPC in the presence of water, but not that of DMPE.
Identifizierung und Synthese von Dimethylalkanen als Sexuallockstoffe weiblicher Miniermotten (Lyonetiidae) / Identification and Synthesis of Dimethylalkanes as Sex Attractants of Female Leaf Miner Moths (Lyonetiidae)
Authors: Francke W. , Toth M. , Szöcs G. , Krieg W. , Ernst H. , Buschmann E.
Published: August 2018

5,9-Dimethylheptadecane and 5,9-dimethylpentadecane represent major components of the sex pheromones of females of the leafminer moths Leucoptera scitella and Perileucoptera coffeella respectively; 5,9-dimethylhexadecane was found in both species as a minor component. These branched chiral hydrocarbons represent a new type of Lepidopteran pheromones, for which simple syntheses are described.
Electrophoresis and Electrofocusing of Phytochrome from Etiolated Avena sativa L.
Authors: Schendel Rudolf , Rüdiger Wolfhart
Published: August 2018

Phytochrome from etiolated oat seedlings (Avena sativa L.) was investigated by “native” gel electrophoresis and by isoelectric focusing. At pH 8 . 8 the Pfr form migrated faster than the Pr form in electrophoresis. We assume a difference in the surface charge rather than a difference in shape for the phytochrome forms. This assumption was confirmed by isoelectric focusing which clearly showed relatively more negative charge in the Pfr form than in the Pr form. The role of the peptide region from residue 323 to 360 is discussed in this connection. It carries 9 negatively charged residues, it is exposed only in the Pfr form and it has already been described as a signal region for rapid protein degradation (PEST sequence, see Rogers et al., Science 234, 364-368, 1986). The experiments on electrofocusing revealed a microheterogeneity of phytochrome which was present in the native state as well as in the completely unfolded state. The most probable reason could be either posttranslational modification or genetic polymorphism of phytochrome in oat.
Hyperthermia Induced Polyphosphate Changes in Propionibacterium acnes as Studied by 31P NMR
Authors: Kjeldstad B. , Johnsson A . , Furuheim K. M. , Bergan A . Schie , Krane J.
Published: August 2018

The polyphosphate component in MP NMR spectra of the Gram-positive Propionibacterium acnes increased after hyperthermia treatment. The cells were exposed to temperatures in the interval from 15 °C to 45 °C. The amount of polyphosphate increased with increasing temperature. There were no temperature induced changes in the other phosphorous components seen in the spectra with exception of a decrease in ATP for higher temperatures. The increase in polyphosphates was less than that obtained from cells irradiated by near ultra-violet light.
Co-Resistance of Atrazine-Resistant Chenopodium and Amaranthus Biotypes to other Photosystem II Inhibiting Herbicides
Authors: Solymosi P. , Lehoczki E.
Published: August 2018

Biotypes of Amaranthus retroflexus L ., A. hybridus L., A. bouchonii Thell. and Chenopodium album L. insensitive to atrazine were collected from maize monoculture where atrazine had been applied extensively. Atrazine-resistant biotypes of A. retroflexus and A. hybridus showed phenmedipham and lenacil co-resistance and atrazine-resistant biotype of C. album showed fenuron co-resistance. An atrazin-resistant biotype of A. bouchonii with co-resistance to diuron was not resistant to fenuron, lenacil and phenmedipham.
Ethyl 6-Bromo-3-indolcarboxylate and 3-Hydroxyacetal-6-bromoindole, Novel Bromoindoles from the Sponge Pleroma menoui of the Coral Sea
Authors: Guella G. , Mancini I. , Duhet D. , Richer de Forges B. , Pietra F.
Published: August 2018

The demosponge Pleroma menoui (order Lithistida, suborder Trienosina (= Desmophorina), family Pleromidae), collected in the Coral Sea south-east of Noum ea at a depth of 500 m, is proven here to contain the novel alkaloids ethyl 6-brom o-3-indolcarboxylate and 3-hydroxyacetyl-6-brom oindole.
Enzymatic Conversion of Sex Pheromones in Olfactory Hairs of the Male Silkworm Moth Antheraea polyphemus
Authors: Kasang Gerhard , Nicholls Michael , Keil Thomas , Kanaujia Sudha
Published: August 2018

The sex pheromone compound [6,7-3H]-6,ll-hexadecadienyl acetate is enzymatically converted to its corresponding fatty alcohol, aldehyde and acid in living and homogenized olfactory hairs and in other parts of the antennae of the male silk-moth Antheraea polyphemus. The pheromone is metabolized in vitro mainly in the inner hydrophilic compartments, but scarcely in the outer hydrophobic cuticle of the olfactory hairs.
Cellular and Subcellular Localization of Peroxidase Isoenzymes in Plants and Cell Suspension Cultures from Lupinus polyphyllus
Authors: Perrey Ralf , Hauser Marie-Theres , Wink Michael
Published: August 2018

, leaf protoplasts and cell suspension cultures of Lupinus polyphyllus and isolated vacuoles were studied for cellular and subcellular localization of peroxidase isoenzymes. Isoelectric focusing revealed 16 peroxidase isoenzymes. The basic peroxidase isoenzymes are predominantly localized in the vacuole and, to a minor degree, unbound in the intercellular space. The acidic isoenzymes are cell wall-bound in plants and not detectable in suspension-cultured cells. Large amounts (up to 11.0 U/ml) of a single basic isoenzyme are detectable in the spent medium of cell suspension cultures.
Inhibition of de novo Fatty-Acid Biosynthesis in Isolated Chloroplasts by Different Antibiotics and Herbicides
Authors: Feld Andrea , Kobek Klaus , Lichtenthaler Hartmut K.
Published: August 2018

Two natural antibiotics, cerulenin and thiolactomycin, were tested for their inhibitory efficacy on de novo fatty-acid biosynthesis of chloroplasts isolated from oat and spinach seedlings and compared with that of known herbicides. With both antibiotics a strong dose-dependent inhibition of the incorporation of [l-14C]acetate into the fatty-acid fraction of the isolated plastids was detected. The l50-values for the inhibition of acetate incorporation into fatty acids are about 4 µM in the case of thiolactomycin and about 50 µM in the case of cerulenin for both mono-and dicotyledonous plants. These values are much higher than those of the particular graminicides cycloxydim and diclofop (0.15 and 0.1 µM), which were developed to control grass weeds in dicotyledonous crop cultures.
Rapid Responses of Cultured Carrot Cells and Protoplasts to an Elicitor from the Cell Wall of Pythium aphanidermatum (Edson) Fitzp
Authors: Schnitzler Jörg-Peter , Seitz Hanns Ulrich
Published: August 2018

, Allgem eine Botanik und Pflanzenphysiologie, Auf der Morgenstelle Suspension cultured cells of an anthocyanin-containing cell line (DCb) from Daucus carota L. ssp. sativus respond very rapidly to treatment with a soluble carbohydrate elicitor from the wall of the oom ycete Pythium aphanidermatum by synthesizing 4-hydroxybenzoic acid which is incorpo­ rated into the plant cell wall. Enzym es of phenol m etabolism , phenylalanine am m onia-lyase (P A L) and chalcone synthase (C H S), respond to elicitor treatment in different ways. Both the catalytic activity of PAL and its subunit concentration, measured by means of immunoblotting, show a transient increase upon elicitation, whereas CHS the initial enzyme of the flavonoid pathway, is inhibited after administration of the elicitor. and consequently anthocyanin accum ula­ tion ceases. In protoplasts derived from the cultured cells a very similar elicitor-induced response has been observed. Lacking a cell wall, the protoplasts secrete the 4-hydroxybenzoic acid into the culture fluid. The carrot protoplasts isolated by wall degrading enzym es retain their responsive­ ness to the fungal carbohydrate elicitor. The value of the protoplast system for studying the im m ediate events following elicitor treatment is discussed.
The Ability of Ethanolic Extract of Propolis (EEP) to Protect Mice against Gamma Irradiation
Authors: Scheller Stanislaw , Gazda Grazyna , Krol Wojciech , Czuba Zenon , Zajusz Aleksander , Gabrys Janusz , Shani Jashovam
Published: August 2018

Ethanolic extract of propolis (EEP) was tested as a protective agent against gamma irradiation in mice. The mice were exposed to 6 Gy gamma irradiation from a 60Co source, and were treated intraperitoneally with EEP, administered before and after their irradiation. While the non-treated mice expired within 12 weeks, the mice that received a series of EEP treatments survived the irradiation, and their leucocyte count as well as their spleens’ plaque-forming activity returned to normal. It is suggested that an antioxidant and a free radical scavanger in the EEP are responsible for the radiation protective effect of the extract of this natural product.
Effects of Permeabilization on the Biotransformation of Phenylalanine by Immobilized Tobacco Cell Cultures
Authors: Berlin Jochen , Martin Bernd , Nowak Jerzy , Witte Ludger , Wray Victor , Strack Dieter
Published: August 2018

Im mobilized tobacco cells excreted only a small proportion of their main secondary metabolite caffeoylputrescine into the culture medium . Experiments designed to release more of the com ­ pound by permeabilization caused the loss of caffeoylputrescine, probably by oxidative reactions. Moreover, rather mild treatments with permeabilizing agents (e.g. n-propanol) resulted in severe growth inhibition. The ability of permeabilized cells to form caffeoylputrescine and other hy-droxycinnam oyl conjugates from phenylalanine decreased considerably even when such cells were still able to metabolize phenylalanine into various ethyl acetate extractable com pounds (e.g. hydroxycinnamic acids and acetophenones). The formation of new biotransformation products suggests that permeabilized cells could be used as a tool for testing the enzymatic capabilities of a cell culture.
A New-Type Photosystem II Inhibitor which Blocks Electron Transport in Water-Oxidation System
Authors: Koike H. , Asami T. , Yoshida S. , Takahashi N. , Inoue Y.
Published: August 2018

The mode of action of three types of conjugated enamine compounds was investigated by means of thermoluminescence measurement. Cyanoacrylate and 2-(l-ethoxyethylam inom ethylidene)- 4-dodecyl-5,5-dim ethyl-cyclohexane-1,3-dione (ACm12) converted the B-band (30 °C) arising from S2QB
- charge recombination to a downshifted 6 °C-band. This band was proved to be identical with the DCM U-induced Q-band (6 °C) arising from S2QA
- recombination, indicating that these two compounds block QA to QB electron transport. 3-(1-dodecylam inopropyridene)-6- methyl-2H-pyran-2,4-dione (APp12 ), on the other hand, induced an abnormal band peaking at 15 °C between the Q-band and B-band. From the gradual downshift of its peak temperature in titration experiments, this band was assigned to arise from a modified S2QB
- charge pair, in which the properties of either QB
- or S2 is altered. The 15 °C-band showed normal oscillation during the first 2 flashes, but the oscillation was interrupted thereafter. Another therm oluminescence analysis by use of post flash low temperature illumination protocol revealed that APp12 affects neither QA to QB nor QB
2- to PQ electron transport, but specifically blocks S3 to S0 transition. These results indicate that APp12 is a new-type PS II inhibitor.
Chagas' Disease and its Insect Vector. Effect of Azadirachtin A on the Interaction of a Triatomine Host (Rhodnius prolixus) and its Parasite (Trypanosoma cruzi)
Authors: Garcia E. S. , Gonzalez M. S. , Azambuja P. , Rembold H.
Published: August 2018

The ED50 for moulting inhibition by injected azadirachtin A is for fourth instar larvae of all the triatomines, Triatoma vitticepes, T. pseudomaculata, T. maculata, T. brasiliensis, T. lecticularis, T. matogrossensis, T. infestans, Rhodnius prolixus, R. neglectus, R. robustus, Panstrongvlus megi-stus, and P. herrera in the range of 10-25 ng/larva. In Rhodnius prolixus, the survival of T. cruzi was studied after treatment with the drug. If the trypomastigotes were fed in presence of 1.0 (.μg aza­ dirachtin A/ml blood, the number of parasites decreased near to the limit of detection within 30 days. If the drug was applied 20 days after T. cruzi infection, it still completely abolished the parasite in the host’s gut within the subsequent 20 days. The same holds true if the insect larvae were pretreated with azadirachtin A 20 days before the subsequent infection with T. cruzi. Azadirachtin A, if applied at the dose of 1 (μg/ml, did not affect the hemolytic activity of the crop contents or the proteinase content of the intestine. A parallel between azadirachtin effects on the hormone balance of the host and growth inhibition of the parasite is discussed on the basis of the present results.
Cephalic Volatiles Identified in Workers of Mourella caerulea, a Rare Stingless Bee Recently Rediscovered in Southern Brazil
Authors: Wittmann Dieter , Lübke Günther , Francke Wittko
Published: August 2018

From workers of Mourella caerulea, an extremely rare and primitive species of neotropical stingless bees, 101 cephalic volatiles were identified by GC/MS analyses.
Die Biflavonoidausstattung von Philonotis fontana (Hedw.) Brid. (Bartramiaceae) / The Biflavonoid Pattern of Philonotis fontana (Hedw.) Brid. (Bartram iaceae)
Authors: Geiger Hans , Bokel Michael
Published: August 2018

From gam etophytes of Philonotis fontana six biflavonoids have been isolated. Two of them - philonotisflavone and 2,3-dihydrophilonotisflavone - were hitherto unknow; their structures have been elucidated spectroscopically.
Tetra-and Pentacyclic Triterpenoids from Epicuticular Wax of Euphorbia cyparissias L., Euphorbiaceae
Authors: Hemmers Herbert , Gülz Paul-Gerhard , Marner Franz-Josef
Published: August 2018

The epicuticular wax of Euphorbia cyparissias contains pentacyclic triterpenoids (34%) and primary alcohols (31%) as major com ponents. The major triterpenoids are triterpenols (23%) consisting of α-and β-amyrin, glutinol, 24-m ethylenecycloartenol and ψ-taraxasterol. The triter­ penones (10.5%) are com posed of taraxerone. a -and β-amyrinone, lupenone, glutinone, ψ-taraxasterone, β-fernenone and three further unidentified triterpenes. α-Amyrin was found esterified with hom ologous series of fatty acids. Minor components are alkanes, wax esters, aldehydes and free fatty acids.
Biochemical Identification of Sideritis serrata X S. bourgaeana Hybrids by HPLC Analyses of Flavonoids
Authors: Ferreres Federico , Tomás-Lorente Francisco , Tomás-Barberán Francisco A. , Rivera Diego
Published: August 2018

The existence of sympatric interspecific hybrids of Sideritis serrata Cav. ex Lag. and S. bou r­ gaeana Boiss. Reut, has been shown by HPLC analysis of the flavonoid glycosides accumulated in the cell sap, and by the methylated flavonoid aglycones exudated by the plants and deposited onto the plant surfaces. The hybrids tend to produce in a single plant the compounds characteristic of the parental taxa. This “complementation” effect in the hybrids permitted relatively easy detec­tion of F1 hybrids. Generally, there was a close correlation between the biochemical results and a morphological analysis which used the Anderson’s index, although a specimen which morphologi­cally was a hybrid, showed a flavonoid pattern as S. bourgaeana. The external flavonoids analysis has revealed that the activity of sideritoflavone O -methyltransferases is much more important in S. serrata than in S. bourgaeana, while the hybrids show intermediate values. M oreover, S. bour­gaeana accumulates sideritoflavone 3′-m ethylether whereas S. serrata accum ulates the 4′-methylether. The hybrids produce both com pounds in similar amounts. In this study, external flavonoids have proved more useful than vacuolar flavonoid glycosides in the biochemical documentation of hybridization. This is probably due to the fact that methylated flavonoid aglycones are physiologi­cally more stable as they are externally located and therefore preserved from the action of enzymes.
Soluble and Particulate Porphobilinogen-Deaminase from Dark-Grown Euglena gracilis
Authors: Rossetti M. V. , Juknat A. A. , Batlle A. M. del C.
Published: August 2018

A highly efficient method employing NaSCN as a chaotropic agent was used to dissociate the membrane-bound porphobilinogen-deaminase.

The same sequence of steps was applied for purifying both soluble and membrane dissociated porphobilinogen-deam inase. The chromatographic behaviour of both proteins was quite similar. Euglena gracilis deam inase appears to exist in an equilibrium mixture of two active species of relative molecular masses of 40000 and 20000.
Comparative Immunological Studies on the CF1-Complex in Mutants of N. tabacum, Exhibiting Different Capacities for Photosynthesis and Photorespiration and Different Chloroplast Structures
Authors: Radunz A. , Schmid G. H.
Published: August 2018

We have compared by means of rocket immunoelectrophoresis the amount of CF1-complex in N. tabacum mutants with that in the wild type N. tabacum var. John William’s Broadleaf. Some of these mutants differ from the wild type not only by higher photosynthetic and photorespiratory activities but also by their chloroplast structure. The amount of CF1, present was related to the chlorophyll content. However, no correlation between the amount of CF1, present and a higher photosynthetic and photorespiratory activity was found. On the other hand the molar ratio of CF1, to chlorophyll seems to depend in these tobacco mutants on the morphological structure of the chloroplasts. In chloroplasts of green phenotypes, in particular in those of the mutants N. tabacum var. Consolation, var. NC 95 and var. Xanthi with high grana stacking as well as in those of the wild type N. tabacum var. JWB one CF1-complex occurs per 470-770 chlorophyll molecules. Whereas in chloroplasts of the yellow-green phenotypes with relatively more stroma thylakoids the amount of CF1 seems to be increased only by a factor of 3-4. The yellow phenotypes contain on the average 1 CF1-complex per 60 chlorophyll molecules. The CF1-complex in the investigated chlorophyll-deficient tobacco mutants is immunochemically identical to that of the wild type N. tabacum var. John William’s Broadleaf as demonstrated by means of the tandem-crossed immunoelectrophoresis. However, between the CF1-complex of tobacco and that of other higher plants such as spinach Spinacia oleracea, only partial identity is observed. Comparative quantitative determinations have shown that one CF1-complex binds on the average 8-9 CF1-antibodies which shows that the CF1-complex of the ATPase is fully exposed in the thylakoid membrane, offering a large adsorption surface to the antibodies. Furthermore, it appears that in the immediate vicinity of the CF1-complex large amounts of monogalactolipids are located. Thus, we have calculated that in the variegated NC 95 mutant, chloroplasts of the yellow leaf areas, in which only stroma thylakoids occur, exhibiting only photosystem I activity, as well as in chloroplasts of green leaf areas with a normal ratio of grana and intergrana thylakoids, the molar ratio of monogalactolipids to CF1-complex is the same. It looks as if the functionality and activity of the coupling factor of photophosphorylation depended on a certain quantity of monogalactolipid molecules.
Composition of Lipids of Beech (Fagus sylvatica L.) Seed Oil
Authors: Prasad R. B. N. , Gülz Paul-Gerhard
Published: August 2018

The lipid composition of beech (Fagus sylvatica) seeds is reported in the present study. Triacylglycerols (94.8% ) were found to be the major component in the oil followed by sterols (0.9% ) diacylglycerols (0.8% ), phospholipids (0.7% ), free fatty acids (0.5% ) and monoacylglycerols (0.3% ) in minor quantities. The composition of molecular species of triacylglycerols was analyzed by GC on the basis of chain length and C-57 was found to be the major species followed by C-55, C-59, C-53 and C-61. The sterol fraction constituted β-sitosterol and stigmasterol with 89.3 and 10.7% respectively. Phosphatidylinositol and phosphatidylethanolamine were the two phospholipids with 55 and 45% present in the phospholipid fraction of the beech seed oil. Oleic, linoleic and palmitic acids were found to be the major fatty acids in all the acyl lipid classes with small variations in quantities.
Microbial Formation of Substituted Styrenes
Authors: Arfmann Hans-Adolf , Abraham Wolf-Rainer
Published: August 2018

Various mono- and disubstituted cinnamic acid derivatives and aromatic carboxylic acids with saturated side chains were incubated mainly with Bacillus, Candida, Hansenula, and Saccharomyces strains. The cinnamic acids carrying a hydroxy- and/or a methoxy group at the 3- and/or 4-position of the benzene ring were decarboxylated with high yields. Most of the reactions were terminated within 24 to 48 h. Substitution at other ring positions afforded also decarboxylation, but at much lower yields. Derivatives with other residues like methyl, chloride, or bromide were not transform ed to the respective styrene. None of the saturated aromatic carboxylic acids could be decarboxylated by the strains used.
Reduction in Symptom Expression of Belladonna Mottle Virus Infection on Tobacco Plants by Boron Supply and the Antagonistic Action of Silicon
Authors: Bengsch E. , Korte F. , Polster J. , Schwenk M. , Zinkernagel V.
Published: August 2018

Boron and silicon have a dramatic influence on the expression of symptoms caused by plant virus infections. For tobacco plants, boron decreases and silicon enhances symptom expression after belladonna mottle virus infection. Infected leaf tissues are highly enriched on both trace elements. Boron supply stimulates the silicon accumulation. In the applied concentrations the trace elements have no phytotoxic effects on the host. Except endogeneous β-interferones, this could be the first example of antiviral action without any cytotoxicity.
Singlet Oxygen Mediated Photobinding of 8-Methoxypsoralen to DNA and Genotoxicity in E. coli
Authors: Henegouwen Gerard M. J. Beijersbergen van , Wijn Edith T. , Schoonderwoerd Simon A. , Vries Henk de , Dall’Acqua Francesco
Published: August 2018

Although oxygen dependent photoreactions of 8-methoxypsoralen (8-MOP) are known, damage to DNA is mostly considered to proceed via photocycloaddition to this biomacromolecule. In this study the survival of colony forming ability of E. coli K 12/343, which is deficient in DNA-repair capability, appeared to be lower in D2O than in H2O after exposure to the combination of 8-MOP and UV-A . Photobinding to bacterial DNA was ∼40% higher in D2O than in H2O. How ever this last difference was found only when the bacteria were kept in the reaction medium for 1 h at 37 °C after the irradiation was stopped and not when they were plated out immediately afterwards. The results indicate that in this bacterial test system 1O2 mediated photobinding of 8-MOP to DNA contributes to the genotoxic effect observed.
First Glance on the Three-Dimensional Structure of the Photosynthetic Reaction Center from a Herbicide-Resistant Rhodopseudomonas viridis Mutant
Authors: Sinning I. , Koepke J. , Schiller B. , Michel H.
Published: August 2018

A first model of the three-dimensional structure of the photosynthetic reaction center of the mutant T1 (SerL 223 → Ala, ArgL 217 → His) from Rhodopseudomonas viridis, resistant toward the triazine herbicide terbutryn (2-methylthio-4-ethylamino-6-f-butylamino-5-triazine), has been developed from X-ray data measured to a resolution of 2.5 Å. The secondary quinone, QB, which in T1 binds better than in the wild type, is present in the crystals. Both substituted residues are clearly visible in the difference fourier map. The replacement of these two residues in the QB site causes only minor changes in the overall structure of the protein.
Mode of Action of Herbicides Affecting Acetyl-CoA Carboxylase and Fatty Acid Biosynthesis
Authors: Lichtenthaler Hartmut K.
Published: August 2018

The mode of action of cyclohexane-l,3-dione-type (cycloxydim, clethodim, sethoxydim, tralkoxydim) and aryloxyphenoxypropanoate-type herbicides (diclofop, fenoxaprop, haloxyfop, fluazifop) is summarized in this review. Both herbicide classes, though structurally completely different, specifically block the same target enzyme i.e. the plastid acetyl-CoA carboxylase (ACC) (EC 6.4.1.2). Most members of the Poaceae are sensitive towards both herbicide groups, whereas other monocotyledonous plants as well as the dicotyledonous plants appear to be resistant. This resistance, which can be found on the level of whole plants, in isolated chloroplasts and also on the level of ACC-enzyme preparations, is apparently due to a modification of the target enzyme ACC. Within the sensitive grass family some members (Festuca and Poa species) are partially tolerant against both graminicide groups. In the case of cyclohexanedione herbicides the tolerance seems to be due to a reduced sensitivity of the target enzyme. In the case of aryloxyphenoxypropionic acid herbicides the tolerance is apparently based on a combined action of cytoplasmic factors (metabolization?) and a slightly reduced sensitivity of the target enzyme. From differences in the sensitivity of certain grasses against the two herbicide classes it is concluded that both graminicide groups bind to the same binding domaine of the ACC enzyme but possess different subsites. The consequences of the block of de novo fatty acid biosynthesis in the plastids of sensitive plants is the lack of glycerolipid and biomembrane formation which finally causes cell death in the meristematic tissues.
Acetolactate Synthase and Ketol-Acid Reductoisomerase: Targets for Herbicides Obtained by Screening and de novo Design
Authors: Schloss John V. , Aulabaugh Ann
Published: August 2018

Several major classes of herbicides, discovered by conventional screening techniques, have been found to inhibit the first common enzyme of branched-chain amino acid biosynthesis, acetolactate synthase, as their mode of action. These herbicides seem to bind to an evolutionary vestige of a quinone-binding site, extraneous to the active site, that is present due to the evolutionary history of this enzyme. Besides their herbicidal effect on sensitive plants, these compounds can effect stasis in the growth of bacteria and yeast. Recently is has been reported that an experimental herbicide from Hoechst. Hoe 704. that was discovered by conventional screening techniques, inhibits the second common enzyme of branched-chain amino acid bio- synthesis [Schultz etal., FEBS Lett. 238, 375-378 (1988)]. We have also recently designed novel reaction-intermediate analogs (e.g. N-isopropyl oxalylhydroxamate) that arc exceptionally potent (Ki = 22 pM: half-time for release approximately six days) and selective inhibitors of the second common enzyme, ketol-acid reductoisomerase. Both of these selective inhibitors of the second common enzyme will kill sensitive plants, but will only inhibit the growth (without killing) of bacteria. The effects in bacteria parallel those obtained by mutations in the relevant genes, where loss of either the first or second common enzyme in the pathway gives an organ- ism that is auxotrophic for branched-chain amino acids, but does not result in a conditionally lethal phenotype. Higher plant mutants have only been obtained to date that arc deficient in functional leucine-specific gene products (as yet uncharacterized), threonine deaminase (isoleucine specific), and dihydroxyacid dehydratase (common). The phenotypes of these mutants. at least at the level of cell culture, are similar to those of their bacterial counterparts, in that auxotrophy, but not conditional lethality, is obtained. These results highlight the potential non-equality of the enzymes of branched-chain amino acid biosynthesis as targets in herbicide design.
Adenylate Kinase from Maize Leaves: True Substrates, Inhibition by P1 , P5-di(adenosine-5′) pentaphosphate and Kinetic Mechanism
Authors: Kleczkowski Leszek A. , Randall Douglas D. , Zahler Warren L.
Published: August 2018

Purified maize leaf adenylate kinase (AK) was shown to use one molecule each of free ADP and Mg-ADP as well as free AM P and Mg-ATP as substrates in the forward and reverse reaction, respectively. This was deduced from substrate kinetic studies which were carried out under conditions of strictly defined concentrations of free and Mg-complexed adenylate species and under controlled free magnesium levels. Apparent Km values of the substrates of AK were 3 and 6 μM for ADP and Mg-ADP, respectively (forward reaction), and 69 and 25 μM for free AMP and Mg-ATP, respectively (reverse reaction). The enzyme was competitively inhibited by P1,P5-di(adenosine-5′)pentaphosphate (Ap5A), a bisubstrate analog of AK reaction, with apparent Ki values in the range of 11 -80 nM , depending on variable substrate. Substrate kinetic studies and inhibition patterns with Ap5A suggested a sequential random kinetic mechanism in both directions of the reaction. These properties of a higher plant AK are similar or analogous to those previously established for the enzyme from yeast and non-plant tissues.
Bioavailability of Iron and Cyanide from 59Fe-and 14C-Labelled Hexacyanoferrates(II) in Rats
Authors: Nielsen Peter , Dresow Bernd , Fischer Roland , Heinrich Hellmuth C.
Published: August 2018

“Soluble” (KFeIII[FeII(CN )6]) and “insoluble Prussian blue” (FeIII
4[FeII(CN)6]3 labelled with 59Fe either in the ferric (FeIII) or ferro (FeII) position and 14C in the cyanide group were synthesized and administered intraperitoneally or orally to adult female rats with normal body iron stores.

Following i.p. injection of KFe[Fe(CN)6], the colloidal complex is disintegrated into ferric iron and hexacyanoferrate(II) anion almost completely. About 96% of the ferric iron was retained in the body. Nearly 90% of both ferrous iron and cyanide were excreted with the urine within 7 days after i.p. injection, indicating that most of the undissociated hexacyanoferrate(II) anion ([Fe(CN)6]4-) was excreted through the kidney. Only 9% of the ferrous iron from [Fe(CN)6]4- was found mainly in carcass, liver and gut. As the 59Fe/14C-ratios in organs were found close to 1.0, the dissociation of the hexacyanoferrate(II) anion can only be small in vivo. No detectable 14CO2-activity (< 0.01 %) was monitored in the breath of rats after i.p. injection of the 14C-labelled KFe[Fe(CN)6], also indicating that no significant amounts of cyanide were released after parenteral administration.

After oral administration of the soluble and insoluble Prussian blue, 0 .3 -0 .7% of the ferric iron was absorbed and retained mainly in carcass, liver and blood. Only 0.06-0.18% of the ferrous iron was absorbed and mostly excreted with the urine (0.05-0.15%), so that only 0.01-0.03% of the oral ferrous 59Fe was retained in the body after 7- 10 days. Very small fractions of 14C-label from the 14CN-group of the soluble and insoluble hexacyanoferrate(II) were observed in the exhaled air (0.04-0.08% of the oral dose). From the 14CO2-exhalation, the 14Curine excretion and the distribution of iron in blood and organs it can be concluded that the hexacyanoferrate(II) moiety disintegrated only to a small extent in the intestinal tract after oral administration. From a dose of 36 mg hexacyanoferrate(II)/kg, an amount of free (non complex bound) cyanide can be calculated which is in maximum two orders of magnitude below the LD100-level. Thus, the very low bioavailability of iron and cyanide from hexacyanoferrate(II) compounds after oral application is demonstrated in rats. In the case of a severe nuclear accident, appropriate doses of “soluble” and “insoluble” Prussian blue can be used as safe and effective antidote against radiocaesium contamination.
Anticytokinin Activity of N-Phenyl-and N-Pyridylcarbamates
Authors: Shimizu Ryo , Iwamura Hajime , Fujita Toshio
Published: August 2018

A new class of non-adenylate anticytokinins, alkyl and phenyl N-phenylcarbamates and related phenyl N-pyridylcarbamates, has been developed. They have a structure that has an immediate resemblance to the non-adenylate class of cytokinins, N ,N′-diphenylureas, and N-pyridyl-N′-phenylureas, and the design of the molecule was made based on insight into the bioisoteric nature between the previous, non-adenylate s-triazine anticytokinins and the carbamate and urea structures. The activity in terms of the I50 value of the most potent members, 4-fluoro- and 4-chlorophenyl N-(2-chloro-4-pyridyl)carbamates, was 0.3 - 0.5 x 10-6 M when examined by the tobacco (Nicotiana tabacum L.) callus assay in the presence of 0.05 x 10-6 M kinetin.
Influence of Oxime Ether Safeners on Glutathione Content and Glutathione-Related Enzyme Activity in Seeds and Seedlings of Grain Sorghum
Authors: Yenne Samuel P. , Hatzios Kriton K.
Published: August 2018

The influence of the oxime ether safeners, oxabetrinil and CGA-133205, on glutathione content, glutathione reductase (EC 1.6.4.2), and glutathione-S-transferase (EC 2.5.1.18) activity in seeds and seedlings of grain sorghum (Sorghum bicolor (L.) Moench. var. Funk G-522-DR) was investigated. Plant material for these experiments was derived from seed that was either untreated, or treated with 1.25 or 0.4g ai/kg seed of oxabetrinil or CGA-133205, respectively. Measurements were conducted at 0, 1, 2, 4, 8 , 12, 24, 36, and 72 h after the initiation of germination. In safener-treated sorghum seeds, the levels of total and reduced glutathione decreased gradually after the initiation of germination reaching a low at 8 to 12 h and then increased continuously reaching a maximum at 48 h. The greatest increases in glutathione levels were observed in oxabetrinil-treated sorghum seedlings. Glutathione reductase activity was consistently higher in untreated seeds of grain sorghum for the first 24 h of imbibition, but at 36 to 72 h glutathione reductase activity increased in the safener-treated tissues. CGA-133205 appeared to have a greater stimulatory influence on the activity of glutathione reductase than did oxabetrinil. For the first 8 h after germination was initiated, glutathione-S-transferase activity in oxabetrinil- and CGA-133205-treated seeds remained enhanced compared to that of untreated seeds, but was at or below the levels of the activity of glutathione-S-transferase extracted from untreated seeds for the remainder of the experiment. Non-enzymatic conjugation of metolachlor with reduced glutathione increased as the pH of the reaction solution increased from 6.0 to 8.0. Oxabetrinil at 1 to 40 μM and CGA-133205 at 1 to 160 μm enhanced nonenzymatic conjugation of m etolachlor with glutathione. At 80 and 160 |j.m , oxabetrinil reduced the am oun t of non-enzym atic conjugation of metolachlor. Oxabetrinil conjugated with reduced glutathione at low rates either enzymatically or non-enzymatically at pH 8.0 while CGA-133205 did not at any pH. In the presence of metolachlor, the amount of non-enzymatic conjugation of oxabetrinil was decreased, indicating that metolachlor is more reactive towards glutathione than is oxabetrinil. Overall, these data suggest that during the early stages of seed germination and seedling development of grain sorghum , oxim e ether safeners can enhance the detoxication of the herbicide, metolachlor, through enzymatic or non-enzymatic conjugation to reduced glutathione by enhancing either the level of reduced glutathione and/or the activity of glutathione-related enzymes.
Carbohydrate Tolerance Status in Patients with Myocardial Infarction
Authors: Rahman M. Ataur , Begum Hasna , Samad Abdus , Shahjehan S.
Published: August 2018

Hyperglycemia is an important independent risk factor in the development of coronary artery disease. Sixty one patients suffering from chronic and acute myocardial infarction out of which 12 patients were diabetic and 10 normal control subjects were investigated. The patients without diabetes and control subjects were subjected to oral and intravenous glucose tolerance tests. It was observed that the post load glucose level of most of the patients and fasting insulin level of patients without diabetes were higher as compared with control subjects. From the intravenous glucose tolerance test, half life of glucose and glucose assimilation coefficient were determined. Half life of glucose was increased significantly and glucose assimilation coefficient was decreased in the patients with myocardial infarction as compared with those of control subjects. The observations confirm that carbohydrate intolerance in myocardial infarction is not due to suppression of insulin secretion but due to peripheral utilization.
Alterations in 1,4-Benzoxazinone Levels Following Inoculation with Stem Rust in Wheat Leaves Carrying Various Alleles for Resistance and Their Possible Role as Phytoalexins in Moderately Resistant Leaves
Authors: Bücker Claudia , Grambow Hans J.
Published: August 2018

The contents of 1,4-benzoxazinone derivatives in wheat plants infected with Puccinia graminis Pers. f. sp. tritici Ericss. & Henn, race 32, and in uninfected controls were examined in four near-isogenic lines of different infection types: Triticum aestivum L., cultivar Prelude Sr5 (highly resistant), Sr24, Sr26 (moderately resistant), and srx (susceptible). In all infection types the contents of DIMBOA -glc and HMBOA -glc decrease with time in the uninfected controls as well as in the infected plants. However, following inoculation, the synthesis of HDIBOA -glc is drastically increased in the moderately resistant cultivars. The results suggest that this fully methylated 1,4-benzoxazinone may function as a phytoalexin in this type of interaction. The benzoxazolinone MBOA which has been described as an in vitro conversion product of the benzoxazinones mentioned above is not detected in inoculated or uninoculated leaves.
Tracing the Human Metabolism of Stable Isotope-Labelled Drugs by ex vivo NM R Spectroscopy A Revision of S-Carboxymethyl-ʟ-cysteine Biotransformation
Authors: Meese Claus O. , Fischer Peter
Published: August 2018

A direct structural identification, and quantitative assessment below the 50 nmol/ml level, of the full pattern of renally excreted metabolites is made possible by 13C NMR measurements of untreated urine samples when stable isotope-labelled (13C) drug analogues are administered to humans. The full potential of the new ex vivo NMR approach is exemplified by a study, for a group of volunteers, of S-carboxymethyl-ʟ-cysteine metabolism. The metabolic sulphoxidation pathway of S-Carboxymethyl-ʟ-cysteine in man, accepted so far, needs to be profoundly revised on the basis of the 13C NMR results.
High Oleic Sunflower: Studies on Composition and Desaturation of Acyl Groups in Different Lipids and Organs
Authors: Sperling Petra , Hammer Ute , Friedt Wolfgang , Heinz Ernst
Published: August 2018

A selection of lipids from achenes, cotyledons after germination, roots and leaves of normal and high oleic varieties of sunflower were analyzed with regard to their fatty acid profiles. The lipids included triacylglycerol and phosphatidylcholine as ER-made components and mono-and digalactosyl diacylglycerol as plastid-localized glycolipids. A comparison of fatty acid pat­ terns showed that the block in oleate desaturation of the high oleic variety is confined to the ER of fat accumulating embryos, but that upon germination the oleate desaturation in the cotyledonary ER is rapidly derepressed. These data are supported by enzymatic experiments. In microsomes from maturing fruits of the high oleic variety oleoyl-phosphatidylcholine desaturase could not be detected, whereas o leoyl-CoA : lyso-phosphatidylcholine acyltransferase and components of the microsomal electron transport chains were not affected. A correlation in the expression of desaturation blocks in seed and root fatty acids as observed in mutants of other species was not observed which, therefore, cannot be generalized. Our data are discussed in terms of the existence of two ER-specific oleate desaturase activities.
Light-Induced Oxidation-Reduction Reactions of Photosystem II in Dichlorophenyl-dimethyl Urea (DCM U) Inhibited Thylakoids
Authors: Nemson Jeff A. , Melis Anastasios
Published: August 2018

Illumination of thylakoid membranes in the presence of 3-(3′,4′-dichlorophenyl)-1,1-dimethyl urea (DCMU) causes the reduction of the primary quinone acceptor QA of photosystem II (PS II) and the storage of a positive charge on the donor side of the photochemical reaction center. These oxidation-reduction reactions are accompanied by characteristic changes of absorbance in the ultra-violet region of the spectrum. The PS II-related absorbance difference spectra (250 -350 nm) were compared in control and hydroxylamine-treated thylakoid membranes, and in thylakoids suspended in the presence of carbonyl cyanide-p-(trifluoromethoxy)- phenylhydrazone (FCCP). The light minus dark difference spectra were dominated by the Q-
A minus QA difference spectrum. Qualitatively, the three spectra were identical in the 300 - 350 nm region, however, they showed distinct differences in the 250 - 300 nm region. The latter arose because of different contributions from the donor side of PS II in the thylakoid membrane of the three samples. The result suggested that FCCP acts as the ultimate electron donor in DCMU - poisoned chloroplasts. Therefore, the absorbance difference spectrum in the presence of FCCP reflected a contribution from the Q-
A minus QA component only. Deconvolution of the absorbance difference spectra of control and hydroxylamine-treated thylakoids yielded difference spectra attributed to the oxidation of a component on the donor side of PS II. This component did not conform with the known Mn(III) → Mn(IV) transition. Rather, it indicated the oxidation of a modified form of Mn in the presence of DCMU , probably a Mn(II) → Mn(III) transition. The results are discussed in terms of the use of DCMU - poisoned thylakoid membranes in the quantitation of the primary quinone acceptor QA by spectrophotometric approaches.
X-Ray and Fluorescence Studies on Phospholipid Bilayers. IX. Interactions with Pentachlorophenol
Authors: Suwalsky M. , Espinoza M. A. , Bagnara M. , Sotomayor C. P.
Published: August 2018

Pentachlorophenol (PCP) is a widely used and highly toxic fungicide. Its toxicity is mainly expressed at the cell membrane level. It is, therefore, of interest to test its ability to alter the lipid bilayer organization. The present study was performed by X-ray diffraction techniques on dimyristoylphosphatidylethanolamine (DMPE) and dimyristoylphosphatidylcholine (DMPC) bilayers and by fluorescence on DMPC liposomes. These two phospholipids are respectively found at the inner and outer monolayers of human erythrocyte membranes. Each type of phospholipid was made to interact with different concentrations of the sodium form of PCP in absence and in presence of water. It was found that PCP significatively affected the structure of both phospholipids, being the damage much higher in DM PC bilayers.
Directed Growth of Fungal Hyphae in an Electric Field
Authors: Gruler Hans , Gow Neil A. R.
Published: August 2018

The galvanotropic response of the mycelial fungus Neurospora crassa is investigated. The angle distribution function of growing hyphae is described by a generating function which contains two non-trivial terms; one for directional growth and one for bidirectional growth. The following results were obtained, (i) Germ tubes grew towards the anode, (ii) The cellular response was linear for small sized cells and weaker electric fields. The galvanotropic constant, KGROW, which describes the linear response, was small for short germ tubes or hyphae (AGROW
-1 = -20 V -cm-1 for I0 = 10 |am) and large for longer cells (AGROW
-1 = -1 -7 V ·cm-1 for I0 = 100 μm). The growth coefficient KP of (-18.5 mV) describes the response independent of cell size. The linear response is explained by the field-induced distribution of charged membrane- bound proteins essential for galvanotropism. (iii) For E > E0 = 3.8 V ·cm-1, the linear response is inhibited (inhibition coefficient K1 = 1.11). The inhibition is explained by field-induced changes of the membrane potential, (iv) The galvanotropic response of longer hyphae was bidirectional. The cells grew on average perpendicular to the applied field. The bidirectional response is proportional to Er with a bidirectional growth coefficient K2 of -(0.25 V)-2. The bidirectional growth is explained by the inhibition of the directed growth process. The transition from anode-directed to bidirectional growth was a function of the applied electric field as well as of the tube length (directed growth for E2-l0< 4.4V2·cm-1 and bidirectional growth for E2·l0> 4.4 V2· cm-1).