bluuebunny/crossref_metadata_2025 huggingface dataset:
Research on Biochemistry of Herbicides: An Historical Overview
Authors: Moreland Donald E.
Published: August 2018

Otto Warburg, the father of cellular bioenergetics, seems to have been the first investigator to report on inhibition of a plant biochemical reaction by a progenitor of a selective herbicide. The year was 1920 and the compound was phenylurethane (ethyl N-phenylcarbam ate or EPC). Warburg found that it strongly inhibited photosynthesis in Chlorella. EPC did not develop into a commercial herbicide, but the isopropyl derivatives (propham and chlorpropham) which were introduced in the late 1940s became selective herbicides. The phenylureas (monuron and diuron) were introduced in the early 1950s and shortly thereafter, interference with the Hill reaction by both phenylureas and phenylcarbamates was reported. During the latter part of the 1950s, into the 1960s, and even now, additional herbicidal chemistry was and is being announced that interferes with the Hill reaction. Duysens, in 1963, identified the site of action of diuron, i.e., on the acceptor side of PS II. Corwin Hansch, in 1966 introduced the SAR or QSAR concept in which inhibitory action of Hill inhibitors was related to various chemical and physical parameters.

Because of differential responses to partial, thylakoid-associated reactions, the Hill inhibitors were subsequently divided into two groups: pure electron transport inhibitors (phenylureas, s-triazines, triazinones, and uracils) and inhibitory uncouplers (acylanilides, dinitrophenols, benzimidazoles, dinitroanilines, and benzonitriles). The inhibitory uncouplers (dinoseb-types), unlike the diuron-types, uncoupled photophosphorylation by interacting with the coupling factor complexes in both chloroplasts and intact mitochondria. Additionally, the bi-pyridyliums were shown to be reduced by PS I, hence, diverted electrons from the native acceptor.

Field observations of triazine resistance were reported in 1970 and resistance was subse­ quently demonstrated at the thylakoid level. Application of the techniques of genetic engineering and biotechnology resulted in identification of the 32 kD a herbicide-binding protein and determination of its amino acid sequence. Crystallization and X-ray examination of the photosynthetic reaction center from Rhodopseudomonas by Michel et al. in the mid-1980s provided new models to account for interactions of herbicides with the D -1 protein.

During the 1980s, herbicides were identified that interfered with biochemical machinery in chloroplasts that is not involved in electron transport and light harvesting: inhibition of lipid biosynthesis by aryloxyphenoxypropionates and cyclohexanediones, aromatic amino acid bio­ synthesis by glyphosate, branched chain amino acid biosynthesis by sulfonylureas and imidazolinones, carotenoid biosynthesis by pyridazinones, and porphyrin biosynthesis by diphenylethers and oxadiazoles. The current status of research in most, if not all, of the above areas was reported through oral and poster presentations at this Omiya Symposium.
N-Methylanilinocyanoacrylate Photosystem II Inhibitors. Structure-Activity Relationships
Authors: Banham Wendy K. , Huppatz John L. , Phillips John N .
Published: August 2018

Many 3-N-methylanilino cyanoacrylate derivatives are potent inhibitors of photosynthetic electron transport at the PS II level in a thylakoid system isolated from Pisum sativum. These inhibitors are somewhat unusual in that they take more than 15 min to equilibrate with the binding site in contrast to most classical PS II inhibitors which tend to equilibrate rapidly i.e. within the mixing time of seconds. The effects of mono-and disubstituents in the aryl nucleus on inhibitory activity were studied. The nature and position of the substituent had no detectable influence on equilibration rate but a pronounced influence on inhibitory activity as measured by equilibrium pI50 values. Substituent position enhanced inhibitory activity in the order 3′ > 2′ ⋙ 4′ . As regards the nature of the substituent, size appeared to be the most important parameter -the smaller the substituent the greater the activity. Such influences were in contrast to those in analogous 3-anilino-and 3-benzylamino-2-cyano-acrylate series where the comparable order of substituent position effect was 3′ and 4′ ⋙ 2′ and where substituent hydro-phobicity rather than size was the most important factor. Disubstituted fluoro derivatives have given interesting insights into the preferred orientation of these inhibitors at the binding site with the 2′-and 5′-positions interacting positively, the 4′-position, negatively, and the 3′-position neutrally.
On the Orientation of Photosystem II Inhibitors in the QB-Binding Niche: Acridones, Xanthones and Quinones
Authors: Oettmeier Walter , Masson Klaus , Kloos Ralf , Reil Ellen
Published: August 2018

The orientation of acridones, xanthones, 1,4-benzo-and naphthoquinones within the photosystem II QB herbicide-binding niche was studied by means of mild trypsination and by estimation of pI50-values in Chlamydomonas reinhardtii D 1 mutants (Val219 > lie, Ala251 > Val, Phe255 > Tyr, Ser264 > Ala, Asn266 > Thr, and Leu275 > Phe). As judged from the R/S-values (ratios of I50 -values resistant versus susceptible type) close to 1 in all mutants, the acridones and xanthones do not have strong interactions with the parent amino acids. Contrary, the quinones exhibit extreme low R/S-values down to 0.003 (for 2,5-dibromo-3-methyl-6-isopropyl-1,4-benzoquinone; DBMIB) in the Ser264 mutant. This extreme negative cross resistance or supersensitivity indicates that the quinones do not form a hydrogen bond to the serine hydroxyl group.
Photosystem II Inhibition by Phloroglucinol Derivatives Having Both Phenol and Urea Functionalities
Authors: Honda Ichiro , Sibagaki Makoto , Yoneyama Koichi , Nakajima Yoshihiro , Konnai Makoto , Takahashi Nobutaka , Yoshida Shigeo
Published: August 2018

Esters of 3-nitrophloroglucinecarboxylic acid were found to be active photosystem II (PS II) inhibitors, as were the amides, indicating that, in their structures, the substituted phloroglucinol nuclei themselves plays a major roles in PS II inhibition. Among the phenylureidoalkyl esters tested, 3,4-dichlorophenylurea compound having two amino hydrogen atoms showed high activities. Optimal activity was associated with compounds in which the oxygen atom and the urea structure in the ester side chain were connected via an ethylene group.
Comparison of Experimental and Calculated Hydrogen Bonding Properties of Some Urea and Triazine Inhibitors of Photosystem II
Authors: Creuzet Sophie , Miranda Teresa
Published: August 2018

Previous studies of structure/activity relationships of photosystem II inhibitors, including comparisons of their inhibitory power in herbicide-resistant and susceptible chloroplasts, have led to predict the role of hydrogen bonding, associated to hydrophobicity, in the binding onto the QB site. The crystallographic structures of bacterial reaction centers now allow these bonds to be identified. In order to be able to understand the binding of various herbicides and the effects of resistance mutations within the QB site, a reliable estimation of hydrogen bonding strengths is needed. We show here, by calculating interactions with model compounds, controlled by physicochemical measurements, that the hydrogen bonding properties of the C = X nucleophilic moiety present in most PS II inhibitors are different for triazines as compared to urea or amide derivatives. Semiempirical methods (AM 1) fail to reproduce the energies of hy­drogen bonds between a triazine ring nitrogen and a phenolic proton. An empirical method (SIBFA), designed to reproduce interaction energies, has been adapted with the aim of calculating the binding energies of various herbicides with models of the QB site.
Structural Analysis of the QB Pocket of the D 1 Subunit of Photosystem II in Synechocystis PCC 6714 and 6803
Authors: Astier Chantal , Perewoska Irene , Picaud Martine , Kirilovsky Diana , Vernotte
Published: August 2018

Various herbicides inhibit photosynthesis by displacing the second electron acceptor QB from its binding site at the D 1 protein. Different amino acid substitutions within this binding site have been found to reduce herbicide affinities, thereby conferring herbicide resistance. In Synechocystis PCC 6714 we have selected 7 single mutants and 6 double mutants resistant to various herbicides due to amino acid substitutions at different positions in the QB pocket. Characterization of these mutants consists in molecular determination of the mutations in the psbAl genes and in transformation of Synechocystis PCC 6803 by the cloned mutated genes to analyze the role of the mutations in the mutant phenotypes. Comparison with equivalent Chlamydomonas mutants is presented. These studies allow us to specify the interactions of several amino acid residues with herbicides and QB and with each other. Furthermore some Synechocystis mutants present additional characteristics such as an increased sensitivity to photoinhibition, or resistance to formate or modification of the oscillatory pattern of oxygen evolution. Among the 6 point-mutations giving herbicide resistance, only those located at the limit of the loop and the parallel helix produced additional effects on photosystem II function.
Effects and Absorption of Sethoxydim on Excised Root Tips of Corn ( Zea mays) and Pea (Pisum sativum)
Authors: Takagi Masae (Kubota) , Hosaka Hideo
Published: August 2018

The mechanism of selective herbicidal action of sethoxydim was investigated by using cultured root tips of corn and pea. Sethoxydim inhibited the growth of susceptible corn root at concentrations of 3 nᴍ and above, but did not affect that of pea at 0.1 mᴍ. Meristematic cells in cultured roots were arrested at the G1 and G2 stages of the cell division cycle by sucrose starvation, and resumed growth and cell division (proliferation) upon sucrose addition. Corn root growth was not inhibited by sethoxydim even at 0.01 mᴍ when the roots were arrested by sucrose starvation. Corn roots that resumed growth upon sucrose provision were more sensitive to sethoxydim than those kept in constant growth condition. Better absorption of [14C]sethoxydim into the meristematic region of corn roots was observed when cells were in the proliferative condition, which was not observed when cells were arrested by sucrose starvation. No stronger uptake of the herbicide was observed into pea meristems in either growth condition. In the cell cycle study, stronger absorption of [14C]sethoxydim into the corn root meristem took place at a certain limited period prior to the S (DNA synthesis) stage. The physiological effects and the better absorption of sethoxydim clearly depended on cell cycle progression of the corn root meristem, while fatty acid synthesis, as well as its inhibition by sethoxydim, was neither associated with cell cycle progression nor with stronger absorption of the herbicide. The selective herbicidal action of sethoxydim may be caused by interference with selected stages (G1 and/or the transition step between G1 and S stages) of the cell division cycle, where affinity sites for the herbicide might be expressed.
Molecular Aspects of Herbicide Action on Protoporphyrinogen Oxidase
Authors: Nicolaus Beate , Sandmann Gerhard , Böger Peter
Published: August 2018

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

The crystal structure of 3-(4-chloro-5-cyclopentyloxy-2-fluorophenyl)-5-isopropylideneoxazolidine- 2,4-dione (BW -4), chlorophthalim and oxyfluorfen were determined by X -ray analysis. The molecular size of these compounds was almost the same, but the angle between the oxazolidine and the phenyl ring (BW -4), the imide and phenyl ring (chlorophthalim ) and between the two phenyl rings (oxyfluorfen) differed.

The phytotoxic activities, determined by growth inhibition of Scenedesmus cells, loss of chlorophyll, and peroxidative destruction of photosynthetic pigments, were different among these compounds. The angle and length of BW-3, BW-4 and oxyfluorfen showing best phytotoxic activity were found approximately 65 -95 ° and 11 - 13 Å, respectively. These preliminary findings indicate that both angle and length of the molecule have some bearing on peroxidative activity.
Vinylogous Sulfonylureas: A New Class of Acetohydroxyacid Synthase Inhibitors Incorporating a Large Bridging Moiety
Authors: McFadden Helen G. , Huppatz John L. , Kennard Colin H. L
Published: August 2018

Several acrylic acid derivatives incorporating elements of sulfonylurea structure around a central vinylogous core were synthesized and found to be moderate inhibitors of the enzyme, acetohydroxyacid synthase (AHAS). Some com pounds showed post-emergence herbicidal activity against mustard. Biological activity was found to be markedly influenced by the nature of the 2-arylcarbamoyl group. When this group contained a phenyl ring the compounds were inactive. A 4,6-dim ethoxypyrimidin-2-ylcarbamoyl function resulted in the best activity but this activity was highly dependent on the nature of the 4,6-substituents on the pyrimidine ring, with 4,6-dim ethylpyrimidines showing very little activity. The structures of the most active compound, ethyl 3-(2-chlorophenyl)sulfonylamino-3-m ethylthio-2-[(4,6-dimethoxypyrimidin- 2-yl)carbam oyl]acrylate, and an inactive analogue, 4,6-dimethylpyrimidin-2-yl-3-(2-chlorophenyl) sulfonylamino-3-methylthio-2-cyanoacrylate, were determined by X -ray crystallography. The resulting structures showed several conformational differences which may play an important role in inhibitor binding to AHAS and the resultant herbicidal activity.
A Herbicidal Inhibitor of Isopropylmalate Isomerase
Authors: Hawkes T. R. , Cox J. M. , Fraser T. E. M. , Lewis T.
Published: August 2018

Nitronate compounds resembling the aci-carboxylate reaction intermediate in the reaction catalyzed by isopropylmalate isomerase were investigated as enzyme inhibitors and potential herbicides. The nitronic acids of 1-hydroxy-2-nitrocyclopentane-1-carboxylic acid, nitroisopropylmalate and of 1-hydroxy -2-nitrocyclohexane-1-carboxylic acid were all potent inhibitors of isopropylmalate isomerase. The nitroalkane/nitronate pK a values of these were 7.3, 9.5 and 11.1, respectively. The perturbed pK a values of the first and last compound were und erstandable on the basis of the opposing effects of 5- and 6-membered ring strain on the ionization of the nitro group. As the only compound significantly in the nitronate form at physiological pH , it was not surprising that 1-hydroxy-2-nitrocyclopentane-1-carboxylic acid was the best herbicide. Its specific mode of action was confirmed by the fact that 1-hydroxy-2-nitrocyclopentane- 1-carboxylic acid inhibited the growth of carrot cells in liquid culture and was specifically reversed by leucine.
Differential Response of Two Soybean Cultivars to Paraquat
Authors: Kim Sangho , Hatzios Kriton K.
Published: August 2018

The soybean cultivars “ Kwangkyo” and “ Hood ” are differentially sensitive to the bipyridylium herbicide paraquat (1,1′-dimethyl-4 ,4′-bipyridiniumion). This was confirmed by visible injury observations, measurements of desiccation levels and chlorophyll content, and tracings of chlorophyll fluorescence induction of fully expanded first trifoliate leaves of these two cultivars after exposure to a wide range of paraquat concentrations. The margin of this intraspecific differential tolerance to paraquat was narrow an d the ratio of the paraquat concentrations causing 50% injury to the tolerant Kwangkyo and to the susceptible Hood soybean (approximate tolerance factor) was found to be 10. Paraquat at 1 μᴍ or higher inhibited rapidly the CO2 fixation capacity of leaf mesophyll cells, isolated enzymatically from both cultivars. Thus, the tolerance of Kwangkyo soybean to paraquat does not appear to result from any differences at the site of paraquat action in chloroplast membranes. At early time periods (30 min to 2 h) after treatment with 100 μᴍ of paraquat, chlorophyll fluorescence induction was completely suppressed in first trifoliate leaves of Hood, but not in those of Kwangkyo soybean. At longer time periods (≧ 3 h), paraquat suppressed chlorophyll fluorescence induction similarly in leaves of both soybean cultivars. These results suggest that reduced mobility or a delayed release of paraquat in the mesophyll cells of Kwangkyo may be involved in the observed tolerance of this soybean cultivar to this herbicide.
Phytoalexin Accumulation in Omithopus sativus as a Response to Elicitor Treatment
Authors: Seifert K. , Härtling S. , Porzel A. , Johne S.
Published: August 2018

An isoflavanoid derivative has been isolated as a phytoalexin from intact plants and cell suspension cultures of Ornithopus sativus after treatment with CuSO4, yeast elicitor, or a spore suspension of Colletotrichum trifolii. Based on its physical and spectroscopic properties the substance was identified as glabridin. After induction, the transient in crease in the content of this phytoalex in was preceded by a transient increase in the activities of PAL and CHS.
A Protein Cross-Reacting with Anti-Spectrin Antibodies is Present in Higher Plant Cells
Authors: Sikorski Aleksander F. , Swat Wojciech , Brzezińska Małgorzata , Wróblewski Zdzisław , Bisikirska Brygida
Published: August 2018

Proteins that react with anti-hum an spectrin antibodies raised in rabbit were found in pea seedlings and leaves. The immunoreactive proteins seem to be associated with the membranes and can be extracted with low ionic strength solutions.
Study on the Influence of Temperature on the Mortality of Tribolium confusum J. du Val. Exposed to Carbon Dioxide or Nitrogen
Authors: Buscarlet Louis A.
Published: August 2018

In the pest control of stored products like grain and flour, treatment with gases like CO2 or nitrogen plays an increasing role, as this type of treatment leaves no residues in the food product and is less questionable than treatment with ionizing radiation. An important pest of stored grain is the beetle Tribolium confusum. T. confusum pupae, youn g and aged adults were exposed to pure nitrogen, CO2 or air at different temperatures between 38 and 46 °C. In nitrogen as well as in CO2 pupae were the most resistant. Nitrogen efficacy on adult mortality was much higher than CO2 which was higher than air. For pupae CO2 was more efficient than nitrogen or air in the range 38 - 45 °C. The temperature dependence of the sensitivity to both gases was noticeable in every stage, particularly below a given specific temperature. It was concluded that the combination controlled-atmosphere-temperature could be a valuable time saving and non aggressive technique for the stored-foods insects control.
Characterization of NO2 Bound to the Plant Cuticle by FT-IR Spectroscopy
Authors: Luque Patricia , Heredia Antonio , Ramírez Francisco J. , Bukovac Martin J.
Published: August 2018

Nitrogen oxide binding to isolated tomato fruit cuticles has been characterized using Fourier transform infrared spectroscopy. The performed infrared analysis indicates that nitration occurs in the flavonoids of mature tomato cuticles.
3 α-Hydroxysteroid-5β-oxidoreductase in Tissue Cultures of Digitalis lanata
Authors: Stuhlemmer Ursel , Haussmann Werner , Milek Frank , Kreis Wolfgang , Reinhard Ernst
Published: August 2018

Putative intermediates of cardenolide biosynthesis, namely progesterone, pregnenolone, 5β-pregnane-3,20-dione or 5β-pregnan-3β-ol-20-one, were administered to light- or darkgrown shoot cultures of Digitalis lanata. The unsaturated com pounds were reduced to their respective 5 a-pregnanes, 5β-pregnane-3,20-dione was reduced to 5β-pregnan-3α-ol-20-one and 5β-pregnan-3β-ol-20-one was isomerized to the respective 3α-pregnane.

Suspension cultures of Digitalis lanata, on the other hand, accumulated both the 3α- and the 3β-isom er of 5β-pregnan-3-ol-20-one when incubated in the presence of 5β-pregnane- 3.20-dione. When 5β-pregnan-3α-ol-20-one was administered the cultured cells accumulated large amounts of the 3β-isomer together with small amounts of 5β-pregnane-3,20-dione, which may be regarded as an intermediate during the isomerization reaction.

Cell-free, buffered extracts from light-grown shoots were shown to reduce 5β-pregnane- 3.20-dione almost exclusively to 5β-pregnan-3α-ol-20-one when 0.05 m MgCl2 were present in the incubation mixture. Under these conditions the formation of 5β-pregnan-3β-ol-20-one was inhibited. The enzyme activity could be recovered from m em brane-free supernatants. Optimum enzyme activity occurred at pH 7.0 and 42 °C. The energy of activation was 56.2 kJ/mol and the enzyme reaction was found to be NADPH -dependent. SH reagents were essential for enzyme activity. The enzyme seems to be specific for 5β-pregnan-3-ones since neither 5 a-pregnane-3-ones nor Δ4/Δ5-pregnenes were reduced.

The NADPH : 5β-pregnane 3α-hydroxysteroid-5β-oxidoreductase described here may play a role in the regulation of cardenolide biosynthesis by removing precursors, such as 5β-pregnane-3,20-dione, from the pathway
Effect of Different Condensed Tannins on Trichoplusia ni Performance
Authors: González-Coloma Azucena , Wisdom Charles S. , Rundel Philip W.
Published: August 2018

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

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

Cultures of the green alga Scenedesmus obliquus were grown in the presence of either the chelating reagent EDTA or NiCl2 in various concentrations and assayed for hydrogenase catalyzed photohydrogen evolution after an anaerobic dark adaptation period. Cultivation of algae in the presence of 100 μm EDTA inhibited the formation of hydrogenase activity by 37%. After a cultivation of the cells in the presence of 5-20 μm NiCl2 photohydrogen evolution was increased by 20-40% . Addition of EDTA up to a final concentration of 1.5 mᴍ had no effect on the activity of hydrogenase in cell-free hydrogenase preparations.

Cultures grown in the presence of radioactive 63NiCl2 incorporated 63Ni in a parallel fashion to the cell growth. In radioactive labeled hydrogenase preparations a co-elution of radioactivity and hydrogenase activity could be observed using gel filtration chromatography.
Proteolysis in Heterocyst-Forming Cyanobacteria: Characterization of a Further Enzyme with Trypsin-Like Specificity, and of a Prolyl Endopeptidase from Anabaena variabilis
Authors: Strohmeier Ulrike , Gerdes Christian , Lockau Wolfgang
Published: August 2018

Soluble extracts of the cyanobacterium Anabaena variabilis ATCC 29413 and an engineered mutant that lacks an intracellular protease cleaving after Lys and Arg (Maldener, Lockau, Cai, and Wolk, Mol. Gen. Genet. 225, 113-120 (1991)) were separated by ion exchange chromatography, and protease profiles determined using azocasein, Nα-benzoyl-ᴅ,ʟ arginine- 4-nitroanilide and N-carbobenzoxy-glycyl-ʟ-proline-4-nitroanilide as substrates. A second enzyme cleaving at the carboxyl side of lysine and arginine, and a prolyl endopeptidase were detected, enriched and characterized. Both proteolytic enzymes appear to be located in the periplasm.
A Study on the Life Time of the S3-State in the Filamentous Cyanobacterium Oscillatoria chalybea
Authors: Schmid G. H. , Bader K. P. , Schulder R.
Published: August 2018

In the filamentous cyanobacterium Oscillatoria chalybea deactivation of the S-states starting from steady-state conditions in which S0 = S1 = S2 = S3 = 25% reveals that S3 deactivates to a finite level of approx. 10%. This level is reached under normal conditions between 10-15 seconds. This quasi metastable S3 meets all requirements for S3 in that one flash eliminates this redox conditions to give S4 and therewith molecular oxygen. An analysis of the cyanobacterial S-state system in the 5-state Kok model shows that the S-state population in the dark adapted sample contains no contribution from S-1 or a more reduced condition which under normal conditions is the case for Chlorella or higher plant chloroplasts. Hence under standard conditions, the Oscillatoria condition is a pure Kok-4-condition in which S0 is the most reduced state. Under these conditions S2 seems to deactivate to S1 and S3 to S2 and to a smaller extent to S0. In the presence of the ADRY-reagent Ant-2-p (2-(3-chloro-4-trifluoromethyl)- anilino-3,5-dinitrothiophene) introduced by Renger (Biochim. Biophys. Acta 256,428,1972), which is supposed to specifically act on the S3-state (and thereby on S2), not only the deactivation kinetic of S3 (and S2) is accelerated (hence the life time of the S3-state is shortened), but also the level of metastable S3 becomes practically zero. An analysis of the deactivation pattern shows that the agent changes the mode of deactivation of the entire system. Thus, it is seen that after deactivation of a sample in presence of this agent the dark population of S-states contains the more reduced redox condition S-1 It looks as if in this condition S2 deactivates not only to S1 but also to an appreciable extent by two steps to S-1 Another agent ABDAC (alkyl-benzyl-dimethyl-ammoniumchloride) seems to lengthen the lifetime of the S2 and S3 condition in this cyanobacterium by apparently acting on the membrane condition.
Correlation between Microwave-Induced Lipid Peroxidation and Liposome Leakage
Authors: Babincová Melánia
Published: August 2018

A direct correlation has been found for the microwave-induced phosphatidylcholine peroxidation and 6-carboxy-fluorescein leakage from liposomes.
Phosphate Starvation and a Glycolytic Bypass Catalyzed by Phosphoenolpyruvate Carboxylase in Suspension-Cultured Catharanthus roseus Cells
Authors: Nagano Mayumi , Hachiya Akiko , Ashihara Hiroshi
Published: August 2018

Pathways involved in the conversion of phosphoenolpyruvate (PEP) to pyruvate, the final step in glycolysis, were investigated after transfer of stationary-phase cells from suspension cultures of Catharanthus roseus to fresh complete or phosphate (Pi)-deficient Linsmaier and Skoog medium. In addition to pyruvate kinase (PK). enzymes that can function in an alternative pathway, namely, PEP carboxylase (PEPC), NAD-malate dehydrogenase and NAD-malic enzyme, were present in significant amounts in C. roseus cells. The activity of PEPC in Pi-starved cells was more than twice that in cells in the complete medium (Pi-fed cells), while that of PK in Pi-starved cells was lower than that in Pi-fed cells. No significant differences were observed in the levels of NAD-malate dehydrogenase and NAD-malic enzyme between these two types of cell. At cytosolic pH, the Km value of PEP (45 μᴍ ) for PEPC was lower than that for PK (100 (μᴍ). The activity of PEPC was inhibited by malate, citrate, aspartate and ATP. The activity of PK was also inhibited by ATP, but to a lesser extent. The cellular levels of PEP, adenylates and malate, which are substrates and effectors of PK and PEPC, in Pi-fed and Pi-starved cells suggest that the contribution of PEPC to the metabolism of PEP increased in Pi-starved cells in vivo. Evidence for operation of a bypass from malate to pyruvate in vivo was supported by the rapid release of 14CO2 from organic compounds derived from fixed NaH14CO3 and from [4-14C]malate.
Pheromones 98* Olfactory Electroantennogram Responses of the Formicine Ants Lasius niger and Formica Species (Hymenoptera: Formicidae) to 3,4-Dihydroisocoumarins
Authors: Kern Friedrich , Bestmann Hans Jürgen
Published: August 2018

Electroantennogram (EAG) studies of the formicine genera Lasius and Formica (Hymenoptera, Formicidae) were carried out with 3,4-dihydroisocoumarins, recently identified as trail pheromones within this ant subfamily. The here investigated formicine species Lasius

niger, Formica rufa, F. fusca and F. sanguinea were all responsive towards stimuli of synthetic 3,4-dihydroisocoumarins. Synthesized samples of natural 3,4-dihydroisocoumarins, found in the hindgut of these species evoke the highest electrophysiological responses while structure analogues were less efficient. Number and position of the methyl groups of test substances were important factors for structure activity in EAG. F. fusca and L. niger showed a stereoisomeric differentiation in EAG responses between (R)- and (S)-isomers of 8-hydroxy-3,5,7- trimethyldihydroisocoumarin, a component in the hindgut of both species. Higher electrophysiological activity for (R)-8-hydroxy-3,5,7-trimethyl-3,4-dihydroisocoumarin in comparison to the (S)-isomer agrees with better behavior responses of previous trail following tests in the case of Lasius niger.
Secretion and Metabolism of Ecdysteroids by Oenocyte-Fat Body Complexes (OEFC) in Adult Males of Gryllus bimaculatus DEG (Insecta)
Authors: Römer Franz , Bressel Hans-Ulrich
Published: August 2018

Extracts of whole adult males of Gryllus bimaculatus show distinct maxima of free ecdysteroids on the 8th, 12th and 14th day after imaginal moult at a breeding temperature of 25 °C. Isolated OEFC of 11 days old males secrete in vitro free as well as conjugated ecdysteroids, although the latter predominate. The bulk of free ecdysteroids seem s to consist of E and 20 E according to their retention times in two HPLC systems. Apart from the polar ones, apolar m etabolites appear during incubation. By esterase the apolar metabolites are mostly split into polar ones, partly into 20 E and E. Further treatment of the polar metabolites with helicase leads again to E and 20 E. OEFC transform [3H]E preferably into apolar and polar conjugates, with dominance of the apolar ones at the beginning and of polar ones in the further course of incubation. Only a small quantity of free 20 E is found during this experiment, but it can be produced in significant quantities by splitting the polar conjugates. N o conversion of [3H]cholesterol into [3H]ecdysteroids could be detected.
Disproportionating Transglycosylase (D-Enzyme) in Green Algae and Cyanobacteria. Partial Purification and Characterization
Authors: Fuchs Birgit , Suttner Petra , Sterner Sabine , Wastlhuber Robert , Loos Eckhard
Published: August 2018

D-Enzyme (4-a-glucanotransferase, EC 2.4.1.25) from cultured symbiotic Nostoc and Chlorella has been partially purified and characterized. The enzyme catalyzes the disproportionation of maltooligosaccharides and is able to form maltooligosaccharides from soluble starch and D-glucose. The properties of D-enzyme from Nostoc and Chlorella are similar with respect to substrate specificity, KM values and pH dependence, but differ with respect to temperature optimum and molecular weight (40 °C/50 kDa and 50 °C/230 kDa for the enzyme from Nostoc and Chlorella, respectively). D-enzyme activity has been demonstrated also in freeliving Anabaena, Chlorella and Chlamydomonas. Its physiological role in symbiotic Nostoc is briefly discussed
The Molar Mass of an Active Photosystem I Complex from the Cyanobacterium Synechococcus PCC 7002
Authors: Tziatzios C. , Schuck P. , Schubert D.
Published: August 2018

The molar mass of photosystem I (PS I) from the cyanobacterium Synechococcus PCC 7002 was determ ined by sedim entation equilibrium analysis in the analytical ultracentrifuge. For that purpose, the “trimeric” form of PS I was isolated and studied in three different nonionic detergents. After determining the partial specific volume of the protein/pigment complex, from the ultracentrifuge data, as (0.788 ± 0.010) ml g-1, Mr was obtained as 830,000 ± 60,000
Elastosis and Cancer
Authors: Lohmann Wolfgang , Schill Wolf-Bernhard , Bucher Dieter , Peters Theofried , Nilles Martin , Schulz Andreas , Bohle Rainer
Published: August 2018

Recently we have shown that the autofluorescence within or just outside of a malignant tumor is rather small or large resp. in com parison to healthy tissue when excited at 365 nm. Studies with unfixed, unstained cryosections of skin with melanom as have revealed bulky fiber-like structures with a high fluorescence intensity just outside of a malignant tum or. Using polarized light, the structures could be identified as elastic fibers. This was also confirmed by studies on arterial walls
Influence of Anti-Inflammatory Flavonoids on Degranulation and Arachidonic Acid Release in Rat Neutrophils
Authors: Tordera María , Ferrándiz María Luisa , Alcaraz María José
Published: August 2018

We assessed the effects of 24 flavonoid derivatives, reported as anti-inflammatory, on lysosomal enzyme secretion and arachidonic acid release in rat neutrophils. Amentoflavone, quercetagetin- 7-O -glucoside, apigenin, fisetin, kaem pferol, luteolin and quercetin were the most potent inhibitors of β-glucuronidase and lysozyme release. The first com pound was also able to inhibit basal release. These flavonoids besides chrysin and to a reduced extent, naringenin, significantly inhibited arachidonic acid release from membranes. A correlation between degranulation and arachidonic acid release was found for this series of compounds. Structureactivity relationships and implications for the anti-inflammatory effects of these flavonoids were discussed
Directed Cell Movement in Pulsed Electric Fields
Authors: Franke K. , Gruler H.
Published: August 2018

Human granulocytes exposed to pulsed electric guiding fields were investigated. The trajectories were determined from digitized pictures (phase contrast). The basic results are: (i) No directed response was induced by pulsed electric guiding fields having a zero averaged field, (ii) A directed response was induced by pulsed electric guiding fields having a non-zero averaged field, (iii) The directed response was enhanced for pulse sequencies having a repetition time of 8 s. (iv) The lag-time between signal recognition and cellular response was 8 - 10 s. The results are discussed in the framework of a self-ignition model
Glassy State in Plant Cuticles during Growth
Authors: Luque Patricia , Heredia Antonio
Published: August 2018

The existence of a glassy state in isolated tomato fruit cuticles was investigated using differential scanning calorimetry. Tomato fruit cuticular membranes showed a glass transition temperature at -30 °C and an additional second order transition temperature near 30 °C. Changes in these temperatures during fruit growth were also studied
Pheromone 97*. Der Sexualpheromonkomplex Des Weiblichen Blutbär Thyria Jacobaeae (Lepidoptera, Arctiidae) /Pheromones, 97*. The Sex Pheromone Complex of the Female Arctiid Moth Thyria jacobaeae (Lepidoptera, Arctiidae)
Authors: Bestmann Hans Jürgen , Janssen Edelgard , Kern Friedrich , Schäfer Doris , Vostrowsky Otto
Published: August 2018

By means of gas chromatographic, mass spectrometric methods and combined GC-electroantennogramm techniques as well as activity comparison with pheromones of related species (3Z,6Z)-c/s-9,10-epoxyeicosadiene 1 and (3Z,6Z)-cis-9,10-epoxyheneicosadiene 2 were identified as the biological active components of the sex pheromone complex of the female arctiid moth Thyria jacobaeae
The Oligomeric Arrangement of the Light-Harvesting Chlorophyll a/6-Protein Complex of Photosystem II
Authors: Jackowski Grzegorz , Kluck Ewa
Published: August 2018

The light-harvesting chlorophyll a/b-protein complex of photosystem II (LHC II) was isolated from carnation (Dianthus caryophyllus L.) leaves by K+-induced aggregation of n-hep-tylthioglucoside-treated photosystem II particles. When solubilized with a mixture of lithium docedyl sulphate, octyl-β-D-glucopyranoside and dodecyl-β-D-maltoside the LHC II was re­ solved by mild sodium dodecyl sulphate-polyacrylamide gel electrophoresis into four oligo­meric forms and a monomeric one. LHC II contained five major polypeptides only two of which (27 and 26 kDa) were found to be its authentic components. The oligomeric forms of LHC II were found to differ in the stoichiometric ratios of the polypeptides present. The 26 kD a polypeptide was enriched in the largest oligomeric forms while the 27 kDa polypep­tide tended to form a monomer or to assemble as lower oligomeric states of LHC II.
Inhibition of the Plastidic Pyruvate Dehydrogenase Complex in Isolated Plastids of Oat
Authors: Golz Andrea , Lichtenthaler Hartmut K.
Published: August 2018

The activity of the plastidic pyruvate dehydrogenase complex (pPDHC) is one source of acetyl-CoA in plastids of higher plants needed for de novo fatty acid biosynthesis. This plastidic enzyme reaction is specifically inhibited by acetylmethylphosphinate (AMPI), a com ­ pound which had hitherto been known only as an inhibitor of the mitochondrial pyruvate dehydrogenase complex (mPDHC). In the test system of isolated intact oat plastids (Avena sativa) [2-14C]pyruvate was used for de novo fatty acid biosynthesis. The incorporation of label from [2-14C]pyruvate in fatty acids was inhibited by AMPI in a dose-dependent manner. The inhibition rose with increasing preincubation time of plastids with the inhibitor. I50 values for the inhibition of de novo fatty acid biosynthesis from [2-14C]pyruvate by AMPI for iso­lated etioplasts and chloroplasts were 4.5 and 80 μm , respectively. The activity of the pPDHC decreased during greening of oat seedlings, as is seen from the decreasing incorporation of [2-14C]pyruvate into fatty acids during the light-induced transformation of etioplasts into chloroplasts. In contrast to the decreasing pPDHC activity, the activity of the plastidic acetyl-C oA synthetase (ACS), which transfers acetate to acetyl-CoA, rose parallel to the transfor­mation of etioplasts into chloroplasts. During the assay time of 20 min we could not detect an incorporation of radiolabel from pyruvate or acetate into β-carotene or any other carotenoid
Hypothesis on the Control of D 1 Protein Turnover by Nuclear Coded Proteins in Chlamydomonas reinhardtii
Authors: Bracht E. , Trebst A.
Published: August 2018

A hypothesis is presented on the events in the degradation of the D 1 protein of photosys­tem II in the light. It proposes the existence of a nuclear encoded cleavage system that is turning over and which is modulated by its phosphorylation state. A new experimental approach is presented in which the D 1 protein degradation under photoinhibitory light is tested in Chlamydomonas reinhardtii grown under phosphate deficiency and pretreated with cyclo-heximide.

Under these conditions the degradation of the D 1 protein is delayed whereas in Chlamydomonas reinhardtii grown in full medium the D 1 protein is rapidly disappearing in high light upon addition of chloramphenicol (CAP) or lincomycin for inhibiting the resynthesis of the D 1 protein . Cycloheximide (CHI) has little effect on photoinhibition in such control cells. In cells grown, however, for 20 h in phosphate deficiency - such that there is not yet loss of photosynthesis capacity -pretreatment with cycloheximide or canavanine in low light the degradation of the D 1 protein even in 6 h high light is prevented to an appreciable extent. Further addition of CAP or lincomycin has only a small effect. [14C]leucine incorporation was used to show that there is no resynthesis and that the presence of the D 1 protein is due to a delay of degradation.

The results are interpreted to show that excess high light which converts the D 1 protein into a potentially, degradable mode is not sufficient for degradation of the D 1 protein. A cleavage system is needed as well. It is postulated that under phosphate deficiency and pre-treatment with CHI or canavanine a nuclear coded cleavage system for the D 1 protein is depleted, i.e. the cleavage system for the rapidly turning over D 1 is also turning over.

It is shown that under phosphate deficiency an alkaline phosphatase activity in the chloroplast and the thylakoid membrane of Chlamydomonas reinhardtii is increased. It is proposed that the ratio of kinase/phosphatase converts an active, stable phosphorylated cleavage system into a labile unphosphorylated and turning over state
Nostodione A, a Novel Mitotic Spindle Poison from a Blue-Green Alga Nostoc commune
Authors: Kobayashi Akio , Kajiyama Shin-ichiro , Inawaka Kunifumi , Kanzaki Hiroshi , Kawazu Kazuyoshi
Published: August 2018

A novel antimitotic compound named Nostodione A (Nd A) was isolated from a terrestrial blue-green alga Nostoc commune. Nostodione A disturbed the mitotic spindle formation of sea-urchin eggs and gave small spindles with low birefringence density. Nostodione A. how­ever, had no phytotoxicity on the germination of a dicotyledonous plant Medicago sativa. Based on the spectral analysis and chemical degradation, the structure of Nostodione A was elucidated
In vitro and in vivo Binding of Epirubicin to Red Blood Cells and Human Plasma Proteins
Authors: Bandak Suzan , Czejka Martin , Schüller Johann
Published: August 2018

In this study, the in vitro interaction of epirubicin (EPR), a cytostatic antibiotic, with plasma proteins (PP), namely α-HSA, γ-HSG, α+β-HSG and with isolated human red blood cells (RBCs) was investigated and further correlated with the in vivo pharmacokinetics and binding of EPR and two of its metabolites, 13-dihydroepirubicin and 7-deoxydoxorubicinone to RBCs. The in vitro encapsulation rate in isolated erythrocytes amounts to 52.9 ± 2.8% and remains constant within the range of studied concentrations (2.5-20 μg/ml). EPR was found to bind differently to the various PP in vitro. Binding to α-HSA amounted up to 51.0 ± 7.10%, to α + β-HSG 79.45 ± 2.7%, to γ-HSG 57.1 ± 2.8%. The in vivo-binding rate of EPR, dihydroepirubicin and deoxydoxorubicinone to RBCs after 5 min of injection was 32 ± 6.96%, 11.6 ± 3.1% and 10.05 ± 3.5% respectively, their availability in serum was 42.6 ± 11.8%, 2.4 ± 0.4% and 1.2 ± 0.67% respectively
Olfactory Male Sensitivity and Its Variation in Response to Fluoranalogs of the Main Pheromone Component of Female Mamestra brassicae
Authors: Nikonov A. A. , Tyazhelova T. V. , Nesterov Ye. A. , Rastegayeva V. M. , Ilyasov F. E. , Mashkin P. V. , Kovalyov B. G.
Published: August 2018

According to the EAG study and the field trapping tests, fluoranalogs of the main phero­mone component of Mamestra brassicae females have been found to possess disguising properties for males when used together with the main pheromone component itself. In males, at low concentrations of the above substances the diminishing of attractivity of these blends correlates with the absence of EAG responses to them. An unequal action of these substances has been revealed in different concentration ranges of odours. The mechanisms of the action of these substances are under discussion
Oxyfunctionalization of α-and β-Pinene by Selected Basidiomycetes
Authors: Busmann Dagmar
Published: August 2018

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

The effects of end-of-day light pulses on thallus expansion, cell size, pigmentation and intracellular accumulation of C and N in the red alga Porphyra umbilicalis were analysed. Red (R) light pulses applied at the end of 12 h white light photoperiod for 14 d stimulated thallus expansion and produced an increase in cell size. Growth rate was higher after red (R) than after blue (B) light pulses. Red or blue light affect thallus expansion, but not the thallus weight, and was partially reversed by far-red (FR) light pulses.

Red light pulses promoted chlorophyll a accumulation whereas B light pulses stimulated the accumulation of phycoerythrin, phycocyanin and soluble protein. The effects of R or B light pulses on pigmentation were partially reversed by FR light, except for phycocyanin. Intracellular C content was similar under both R and B light treatments and higher than after FR light pulses and non-irradiated control. However, intracellular N content was higher after end-of-day R than after end-of-day B light pulses. Total absorptance (400-760 nm) of the thalli was higher after B than R light pulses. However, the ratio of total absorptance and concentration of total pigments (chlorophyll and biliproteins), used as index of light absorp­ tion efficiency, was higher after R than after end-of-day B light pulses. The efficiency of light absorption decreased after the application of FR light pulses. These observations explain the higher growth rate, in terms of thallus expansion, after R than after B end-of-day light pulses and FR treatments. The possible action of phytochrome and a B light photoreceptor in the control of growth and pigmentation in Porphyra umbilicalis is suggested.