bluuebunny/crossref_metadata_2025_split huggingface dataset:
Enhanced Inducibility of Antioxidant Systems in a Nicotiana tabacum L. Biotype Results in Acifluorfen Resistance
Authors: Gullner Gábor , Kőmíves Tamás , Király Lóránt 
Published: August 2018

Abstract
Levels of non-protein thiols (mostly glutathione, GSH), ascorbic acid (AA), and activities of the enzymes ascorbate peroxidase (AP), glutathione reductase (GR) and GSH S-transferase (GST) were determined in cell-free leaf extracts of acifluorfen-resistant and -sensitive tobacco plants. These parameters were examined also in detached leaves of the above plants exposed to acifluorfen stress. In leaves of untreated plants the AA content was by 40% higher in the resist­ ant biotype as compared to the sensitive ones, but the levels of GSH, AP, GR, and GST did not differ significantly in the two biotypes. However, in the resistant leaves stressed by aci­fluorfen the activity of AP readily increased while in the sensitive leaves it did not change. The levels of GSH and the activities of GR and GST markedly increased in both biotypes after acifluorfen stress, but the induction in the resistant leaves was consistently stronger in each case. The AA contents were increased equally in both biotypes. These parameters were much less affected by paraquat stress. The only significant changes were observed at low concentra­tions of this herbicide (8 x 10-9 м): when the thiol content and the activity of GST increased in the resistant leaves.
Enhanced inducibility of antioxidant systems seems to be involved in resistance of tobacco to acifluorfen stress.
Naphthalic Anhydride Induces Imazethapyr Metabolism and Cytochrome P-450 Activity in Maize
Authors: Barrett Michael , Maxson Julie M. 
Published: August 2018

Abstract
Naphthalic anhydride is a seed-applied herbicide safener which reduces the toxicity of ima­zethapyr, an imidazolinone herbicide, to maize (Zea mays L.). Protection of maize from ima­zethapyr was dependent on the amount of naphthalic anhydride applied to the seed. Metabo­lism of imazethapyr by maize roots and shoots was increased by exposure of the roots to a solution containing naphthalic anhydride. Increased imazethapyr metabolism due to naph­thalic anhydride treatment of roots was observed within 4 h following safener exposure. Nitro­gen, carbon monoxide and tetcyclacis inhibited imazethapyr metabolism in maize coleoptiles grown from naphthalic anhydride treated seed. This suggests that imazethapyr is metabolized by a cytochrome P-450 monooxygenase.
Naphthalic anhydride application to maize seed increased the level of cytochrome P-450 in the seedling shoots. Microsomes isolated from coleoptiles grown from naphthalic anhydride treated seed, but not untreated seed, converted bentazon to hydroxy-bentazon but did not me­ tabolize imazethapyr. Protection of maize from imazethapyr damage by naphthalic anhydride is due to a safener-induced higher rate of imazethapyr metabolism associated with elevated cytochrome P-450 levels. However, this was not demonstrated in vitro for imazethapyr.
Influence of Safeners on the in vivo and in vitro Metabolism of Bentazon and Metolachlor by Grain Sorghum Shoots: a Preliminary Report
Authors: Moreland Donald E. , Corbin Frederick T. 
Published: August 2018

Abstract
Metabolism of bentazon and metolachlor by excised shoots and a microsomal fraction iso­lated from the shoots, of 3-day-old, dark-grown, grain sorghum (Sorghum bicolor cv. Funk G 522 DR) seedlings was studied. The effects of seed treatments, on the subsequent metabo­lism of the herbicides, with the safeners naphthalic anhydride, oxabetrinil, and CGA 133205 were compared against surface-sterilization and Captan-treatments. Bentazon was aryl hydroxylated in both in vivo and in vitro studies with the hydroxylated derivative undergoing glycosylation only under in vivo conditions. Both shoots and microsomes isolated from shoots of safener-treated seed showed enhanced metabolism of bentazon relative to the controls. In­ hibition by tetcyclacis, a potent inhibitor of plant cytochrome P-450 monooxygenases, in both the in vivo and in vitro studies, and a requirement for NADPH in the in vitro studies suggested that the formation of hydroxybentazon was mediated by a cytochrome P-450 monooxygenase. Metolachlor was metabolized to polar material and O-desmethylmetolachlor under in vivo conditions. Only the demethylated product was formed in vitro. Shoots isolated from safener-treated seed showed enhanced formation of polar com pounds which were assumed to have arisen from conjugation with glutathione. Tetcyclacis did not affect the formation of the polar components. However, the formation of O-desmethylmetolachlor was depressed in the shoots excised from safener-treated seed under both in vivo and in vitro conditions. Tetcyclacis completely prevented formation of the demethylated metabolite. Hence, formation of this meta­bolite is considered to be P-450 mediated. The differential response obtained with the safeners, i.e., stimulation of aryl hydroxylation of bentazon and depression of metolachlor demethylation, suggests that the reactions are probably catalyzed by different cytochrome P-450 mono­oxygenases.
Antagonistic Interactions of Mefenacet with Inhibitors of Monooxygenases
Authors: Fedtke Carl 
Published: August 2018

Abstract
The monooxygenase suicide inhibitor piperonyl butoxide (PBO) antagonizes the inhibitory activity of the herbicide mefenacet in a root regeneration test system with etiolated cut oat stems. When studying the behaviour of [14C]mefenacet [2-(2-benzothiazolyloxy)-N-methyl-N-phenylacetamide] in cut oat stems that had been pretreated with PBO for 24 h after cutting, an increased rate of uptake and increased concentrations of mefenacet in the tissue were found after PBO as compared to water pretreatment. Increased uptake rates and increased rates of metabolism after PBO pretreatment, supposedly by increased monooxygenation, were also observed with the substrates diuron, 2,4-D and cinnamic acid. Mefenacet induced the same responses as PBO in all systems.
The similar actions of mefenacet and PBO are interpreted to suggest that mefenacet might interfere with monooxygenase enzymes. Similar responses, i.e. stimulation of monooxygena­tion of suitable substrates, have been reported for herbicide safeners. An environmentally con­trolled regulatory response system is suggested to be triggered by the different classes of compounds, mefenacet and similar herbicides, monooxygenase inhibitors, and safeners, and to re­spond with increased enzyme activities in the monooxygenase and glutathione detoxification pathways.
Iridoid Glueosides from Plantago altissima L., Plantago lanceolata L., Plantago atrata Hoppe and Plantago argentea Chaix.
Authors: Handjieva Nedjalka , Saadi Houcine , Evstatieva Ljubka 
Published: August 2018

Abstract
Plantago altissima L., Plantago lanceolata L., Plantago atrata Hoppe and Plantago argentea Chaix. were examined for iridoids. In all four species aucubin and catalpol were found. Globularin and methyl ester of the desacetylasperulosidic acid were isolated for the first time from Plantaginaceae plants (P. altissima and P. lan­ceolata). Asperuloside was found for the first time in P. altissima as well as dihydroaucubin in P. atrata.
Phenolic Compounds from Lactuca viminea L.
Authors: Terencio Mari Carmen , Sanz María Jesús , Fonseca María Luisa , Máñez Salvador , Ríos José Luis 
Published: August 2018

Abstract
The aerial part of Lactuca viminea L. was examined for the presence of phenolic compounds. Six different flavonoids were isolated and identified by UV spectra, TLC, HPLCDAD , 1H NMR and 13C NMR. They were identified as apigenin, luteolin, quercetin, luteolin-7-O-glucoside, quercetin-3-O-glucoside and luteolin-7-O-glucuronide-6″methyl ester. Three phenolic acids were also detected: caffeic, ferulic and chlorogenic acid.
Composition of Iridals, Unusual Triterpenoids from Sword-Lilies, and the Seasonal Dependence of Their Content in Various Parts of Different Iris Species
Authors: Marner Franz-Josef , Kerp Bianca 
Published: August 2018

Abstract
The composition of iridals, new triterpenoids from sword-lilies, and their fatty acid esters in roots, rhizomes and leaves of I. germanica Linn., I. pseudacorus Linn, and two different varieties of I. pallida Lam. was determined. Quantitative analysis of their total content in the various parts of the plants in the course of the year showed specific seasonal changes in rhizomes and leaves. Based on these results the possible significance of these compounds for the plants is discussed.
Odor-Structure Relationships in n-Hexenols and n-Hexenais
Authors: Hatanaka Akikazu , Kajiwara Tadahiko , Horino Hiroshi , Inokuchi Kenichi 
Published: August 2018

Abstract
The relationships between the chemical structures and the odor characteristics were examined on a series of highly purified n-hexenols and n-hexenals (14 isomers). The C6-enals and the corresponding alcohols resembled in odor characteristics each other. However, the odor strength of the aldehydes was 100 - 1000 times higher than those of the alcohols. In the principal components analysis, the position of carbon-carbon double-bond in the C6-compounds was closely related to the scores of the first principal component, whereas the functional groups, hydroxy and formyl groups, were related to those of the second principal component except for (Z)-3-hexenol.
Potential Competency of Glucose Oxidase for Modification of Flower Colour in Carthamus tinctorius
Authors: Saito Koshi 
Published: August 2018

Abstract
Glucose was found to be a potential stimulator of carthamin formation in triturated florets of C. tinctorius. At a 10 mM glucose level, carthamin-producing activity was raised from 3.2- fold (upper) to 2.0-fold (lower) level compared with the control having no sugar. Glucose oxidase (β-D-glucose: oxygen 1-oxidoreductase, EC 1.1.3.4) from Aspergillus niger could catalyze the conversion of precarthamin to carthamin, indicative of flower colour modification in C. tinctorius. For optimum reaction, precarthamin, β-D-glucose, and oxygen were required. No manganese enhanced the catalytic enzyme process.
Analysis of Phenolics of Bud Exudates of Populus koreana, Populus maximowiczii and Populus suaveolens by GC-MS
Authors: Greenaway W. , English S. , May J. , Whatley F. R. 
Published: August 2018

Abstract
Analysis of GC-MS data revealed 76 components of bud exudates from Populus koreana, P. maximowiczii and P. suaveolens (Section Tacamahaca), of which 49 were phenolics. The bulk of the exudates were composed of phenones, pinobanksin-3-acetate and aliphatic esters of caffeic acid. Bud exudates of P. koreana and P. m aximowiczii were virtually identical in composition and closely resembled those of P. suaveolens. The three poplars were alike in having as major com ponents of their bud exudate pentanophenones, which do not occur in the bud exudates of most other poplars. These three Asiatic poplars appear more closely related chemotaxonomically to Section Aigeiros poplars than to those of Section Tacamahaca.
Impact of Aminotriazole and Paraquat on the Oxidative Defence System of Spruce Monitored by Monodehydroascorbic Acid
Authors: Westphal Stefan , Wagner Edgar , Knollmüller M. , Loreth W. , Schuler Paul , Stegmann Hartmut B. 
Published: August 2018

Keywords
Ascorbic acid radical, EPR, Herbicides, Damage to Forest, Antioxidative System
Different Forms of Fructose 1,6-Bisphosphatase in Chlorella
Authors: Grotjohann N. , Schneider G. , Kowallik W. 
Published: August 2018

In crude extracts of Chlorella kessleri two forms of fructosebisphosphatase can be separated by ion exchange chromatography or by acid precipitation. FBPase I is eluted from DEAE cellulose at 200mᴍ KC1 and precipitated at pH 4.5, FBPase II is correspondingly eluted at 310 mᴍ KC1 and soluble at pH 4.5. Both enzymes differ in substrate affinity and degree of cooperativity. Based on literature data, FBPase I is assumed to be of cytosolic and FBPase II of chloroplastic origin. The mole mass of FBPase I is identical (51-65 kDa) at pH 6.5 and pH 8.5. T hat of FBPase II is however, about four times larger at pH 6.5 (257 kDa) than at pH 8.5 (67 kDa). Other pH values have only been tried with crude cell extracts in which still larger mole masses of FBPase resulted at more acidic pH (1349 kD a at pH 6.0). The lower mole mass form of FBPase II shows three times higher catalytic activity. Reducing agents, such as DTT, also increase the activity of FBPase II in vitro.
In vivo, alkalization and production of reducing power occurs in the chloroplast stroma during illumination. If the above alterations exist in vivo, they would be a means to activate FBPase in the light.
Oligomerization of FBPase II to aggregates with altered catalytic activities and kinetic properties is discussed as result of the action of specific wavelengths and to be responsible for differences in carbohydrate metabolism of Chlorella exposed to red or blue light.
Inactivation and Reactivation of the Hydrogenases of the Green Algae Scenedesmus obliquus and Chlamydomonas reinhardtii
Authors: Urbig Thomas , Schulz Rüdiger , Senger Horst 
Published: August 2018

The hydrogenases of the green algae Scenedesmus obliquus and Chlamydomonas reinhardtii were activated under anaerobic conditions. Exposure of whole cells and cell-free homogenates to air lead to a complete inactivation of the hydrogenases. The inactivation in whole cells of Scenedesmus is faster than the inactivation of the cell-free homogenate. Inactivation of the hydrogenases could be reversed by anaerobic readaptation in whole cells. The inactivation of the hydrogenase in homogenates seems to be irreversible. Neither the removal of oxygen nor the addition of ATP, NAD(P)H, sodium dithionite, dithiothreitol, ferredoxin and thioredoxin to homogenates facilitated the reactivation of the hydrogenase.
The occurrence of a hydrogenase regulating factor is discussed.
1HNMR Assignments in Biflavonoid Spectra by Proton-Detected C-H Correlation
Authors: Geiger Hans , Seeger Tassilo , Hahn Hannelore , Zinsmeister Hans Dietmar , Markham Kenneth R. , Wong Herbert 
Published: August 2018

Abstract
The 1H and 13CNMR spectra of some representative biflavonoids have been reinvestigated by proton-detected C-H correlation. Some assignments made in earlier publications are revised. Rules for the influence of one flavonoid moiety upon the chemical shift of the other’s protons are given.
10-Hydroxymajoroside, an Iridoid Glucoside from Plantago cornuti Gouan L
Authors: Handjieva Nedjalka , Taskova Rilka , Popov Simeon 
Published: August 2018

Abstract
10-Hydroxymajoroside, a second representative of the rare majoroside type iridoid gluco-sides, along with the well known aucubin, has been isolated from Plantago cornuti.
Protein Modifications in the D 2 Protein of Photosystem II Affect Properties of the QB/Herbicide-Binding Environment
Authors: Kless Hadar , Oren-Shamir Michal , Ohad Itzhak , Edelman Marvin , Vermaas Wim 
Published: August 2018

Abstract
The D 2 protein contains an extended loop (the D-de loop) between helices D and de at the reducing side of photosystem II (PS II). Characterization of D 2 mutants of the cyanobacterium Synechocystis sp. PCC 6803 has indicated that the length and amino acid com position of the D-de loop are not critical for basic PS II functions, although most of the residues in that region are conserved phylogenetically. Here we show using herbicide binding and electron-flow inhibition measurements that drastic modifications in the D-de loop of the D 2 protein modify the interaction of some PS II-directed herbicides with their binding niche. The stability of (semi-)reduced QB in its binding pocket is altered in at least two of the mutants, as indicated by a shifted peak temperature of the thermoluminescence signal originating from charge recombination involving QB.
These results suggest a close functional association between the D-de loop of the D 2 protein and the QB/herbicide-binding environment, which is viewed as being coordinated mostly by residues of the D 1 protein. This represents one of the first examples of modification of the QB/ herbicide-binding domain by mutations in the D 2 protein.
Molecular Modelling of the Interaction between DCMU and the QB-Binding Site of Photosystem II
Authors: Mackay Simon P. , O ’Malley Patrick J. 
Published: August 2018

Abstract
The prefered binding orientations for the herbicide DCMU within the QB-binding site of the D 1 protein model from a photosystem II reaction centre have been determined. Calculation of the intermolecular energy between the herbicide and the binding site has been instrumental in obtaining optimum positions reinforced by experimental results from mutation studies and herbicide binding to analogous bacterial reaction centres. We have shown that two binding sites are possible, one involving a hydrogen bond to and the other to the Ser 264 residue. In both cases, which are more important for the stabilization of the interactions.
Photosystem II: Thermodynamics and Kinetics of Electron Transport from QA
- to QB(QB
- ) and Deleterious Effects of Copper(II)
Authors: Renger G. , Gleiter H. M. , Haag E. , Reifarth F. 
Published: August 2018

Studies on thermodynamics and kinetics of electron transfer from QA- to QB(QB
-) were performed by monitoring laser flash induced changes of the relative fluorescence emission as a function of temperature (220 K < T < 310 K) in isolated thylakoids and PS II membrane fragments.
In addition, effects of bivalent metal ions on PS II were investigated by measuring conventional fluorescence induction curves, oxygen evolution, manganese content and atrazine binding mostly in PS II membrane fragments. It was found: a) the normalized level of the fluorescence remaining 10 s after the actinic flash (Ft/F0) steeply increases at temperatures below -10 to - 20 °C, b) the fast phase of the transient fluorescence change becomes markedly retarded with decreasing temperatures, c) among different cations (Cu2+, Zn2+, Cd2+, Ni2+, Co2+) only Cu2+ exhibits marked effects in the concentration range below 100 μᴍ and d) Cu2+ decreases the normalized variable fluorescence, inhibits oxygen evolution and diminishes the affinity to atrazine binding without affecting the number of binding sites. The content of about four manganeses per functionally competent oxygen evolving complex is not changed by [Cu2+] < 70 μᴍ.
Based on these findings it is concluded: i) a temperature dependent equilibrium between an inactive (I) and active (A) state of QA
- reoxidation by QB(QB
- ) is characterized by standard enthalpies ΔH° of 95 kJ mol-1 and 60 kJ mol-1 and standard entropies ΔS° of 370 kJ K-1 mol-1 and 240 kJ K-1 mol-1 in isolated thylakoids and PS II membrane fragments, respectively, ii) the activation energies of QA
- reoxidation by plastoquinone bound to the QB site are about 30 kJ mol-1 (thylakoids) and 40 kJ mol-1 (PS II membrane fragments) in 220 K < T < 300 K, and iii) Cu2+ causes at least a two-fold effect on PS II by modifying the atrazine binding affinity at lower concentrations ( ~ 5 μᴍ) and interference with the redox active tyrosine Yz at slightly higher concentration ( ~ 10 μᴍ) leading to blockage of oxygen evolution.
HPLC and in vivo Spectrophotometric Detection of Porphyrins in Plant Tissues Treated with Porphyrinogenic Herbicides
Authors: Duke Stephen O. , Duke Mary V. , Lee Hee Jae 
Published: August 2018

Abstract
Protoporphyrinogen oxidase (Protox) inhibitors and other compounds which block or stimulate the porphyrin pathway can cause sufficient levels of porphyrins to accumulate in plant tissues for severe photo dynamic damage to occur. The gross symptomology for all of these por­phyrinogenic herbicides is similar. Porphyrin accumulation induced by three porphyrinogenic herbicides acifluorfen (AF), δ-aminolevulinic acid (ALA), and 2,2′-dipyridyl (DY) was determined by in vivo spectrophotometry and HPLC methods. The averaged in vivo difference spec­tra between untreated and AF-treated (30 μᴍ for 20 h in darkness) yellow cucumber cotyledon discs approximated the absorption spectra of protoporphyrin IX (Proto IX). There was also an enhanced peak near 503 nm. Treatment of cotyledon discs with ALA alone generated a difference spectrum of protochlorophyllide (PChlide) in combination with Mg -Proto IX or Mg-Proto IX monomethyl ester (Mg-Proto IX ME). With ALA and AF in combination , the PChlide and Mg-Proto IX portions of the difference spectrum were reduced and the Proto IX peak and peak near 503 nm were increased. DY treatment yielded a difference spectrum with peaks approximating those of Proto IX and Mg-Proto IX ME , along with a peak near 503 nm . The presence of all porphyrins detected by in vivo spectrophotometry except for the 503 nm peak was confirmed with HPLC . Proto IX monomethyl ester was found by HPLC to be espe­cially elevated in treatments with AF. The in vivo 503 nm peak and in vitro studies with Protox-containing barley etioplast preparations suggest that p rototetrahydroporphyrin IX (an oxida­tion state intermediate between protoporphyrinogen IX and Proto IX) may accumulate under some conditions. These data demonstrate that rapid in vivo spectrophotometric studies can provide much of the qualitative results of HPLC studies and can confirm that in vitro results correspond with the in vivo situation.
Inhibitory Action of Glufosinate on Photosynthesis
Authors: Wild Aloysius , Wendler Christine 
Published: August 2018

Glufosinate (phosphinothricin) irreversibly blocks the glutamine synthetase which subsequently gives rise to an accumulation of ammonium and to a strong decrease in some amino acids, especially glutamine and glutamate.
Under atmospheric conditions (400 ppm CO2, 21% O2) glufosinate causes a rapid inhibition of photosynthesis, too. H ow ever, under non-photo respiratory conditions (1000 ppm CO2, 2% O2) only a slight inhibition of photosynthesis occurs with glufosinate. Since under both conditions an accumulation of ammonium occurs, it is concluded that inhibition of photosynthesis is not induced by the higher concentrations of ammonium. The results rather suggest that the absence of amino donors in the glycolate pathway leads to a break-down of the transamination reaction of glyoxylate to glycine. This causes an inhibition of photorespiration and as a further consequence the inhibition of photosynthesis. There are two hypotheses for explaining this phenomenon. One of them supposes that the blockade in the glycolate pathway produces a lack of Calvin cycle intermediates which subsequently is the cause of the inhibition of photo synthesis. The other one suggests a direct inhibition of the ribulose-1,5-bisphosphate carboxylase by the accumulation of glyoxylate and P-glycolate.
After treatment with different intermediates of the Calvin cycle and photorespiration to gether with glufosinate no decrease in the inhibition of photosynthesis could be measured. This suggests that the inhibition of photosynthesis is not induced by a depletion of intermediates of the Calvin cycle.
Tests on the effect of glyoxylate and P-glycolate on ribulosebisphosphate carboxylase activity showed that in crude leaves extracts the enzyme activity can only be inhibited by high concentrations of these substances. However, in intact spinach chloroplasts the enzyme activity can be blocked by using much lower concentrations of glyoxylate. This may indicate that the ribulosebisphosphate carboxylase activase is affected by this metabolite and that this may be the reason for an inhibition of photosynthesis after treatment with glufosinate.