bluuebunny/crossref_metadata_2025 huggingface dataset:
Seasonal Variations In Epicuticular Wax Ultrastructures Of Quercus Robur Leaves
Authors: Gülz P.-G. , Boor G.
Published: August 2018

Already the very young leaflets of oak (Quercus robur L.), newly emerging from their buds, are covered by a thin wax layer, but at this time it lacks any wax sculptures or crystalloids. Both in its amount and its composition this wax layer is quite different to that of mature leaves. After leaf unfolding a dynamic biosynthesis of wax lipids is started. Ten days after the leaf has emerged from its bud, wax crystalloids are seen for the first time, developing out of the wax layer in the form of platelets. These crystalloids increase in size and quantity within the next weeks and are present on both leaf surfaces. On the adaxial side a dense and uniform arrangement of fringed edged platelets is observed. Similar dense arrangements of platelets are found on the abaxial leaf side, but with an intensive concentration and orientation around the stomata. All platelets are composed of tetracosanol, the main wax component, accounting for more than 40% of wax. Variations in surface wax ultrastructures are observed in July. Well formed platelets and melted away crystalloids are found close together in distinct parts of the same leaf, both on the adaxial and on the abaxial sides of the leaf. These observations pertain to preparations made from July to November with a trend toward recrystallization in October. High temperature and essential oils may be the reasons for the melting away or solution of the platelets
Plant Metabolism Of Xenobiotics. Comparison Of The Metabolism Of 3.4-Dichloroaniline In Soybean Excised Leaves And Soybean Cell Suspension Cultures
Authors: Gareis Christine , Rivero Christiane , Schuphan Ingolf , Schmidt Burkhard
Published: August 2018

Excised leaves and cell suspension cultures of soybean (Glycine max L.) were incubated with [UL-14C]-3,4-dichloroaniline. The compound was almost completely metabolized after 48 h in both systems; it was apparent that the major detoxification pathways present in the excised leaves were also present in the cultured cells. Besides considerable amounts of insoluble residues, the N-glucosyl and the N-malonyl conjugates of 3,4-dichloroaniline, and a yet unknown metabolite was formed in the excised leaves; tentatively the latter was identified with the 6′-O-malonylester of N-glucosyl-3,4-dichloroaniline. The cell suspension cultures produced predominantly the N-malonyl conjugate, besides negligible amounts of the N-glucosyl conjugate, and insoluble residues; the majority of the N-malonyl compound was excreted into the medium. It was shown, that the metabolism of 3,4-dichloroaniline in excised leaves and cell suspension cultures of soybean was directed towards different end products: the excised leaves were able to make extensive use of cell wall structures as a deposit for xenobiotic bound residues, resembling plants in this respect; lack of these structures in the cultured soybean cells resulted in a soluble end product, namely the N-malonyl conjugate
Properties Of The Plasma Membrane Atpases Of The Halophilic Archaebacteria Haloferax Mediterranei And Haloferax Volcanii
Authors: Dane Michaela , Steinert Kerstin , Esser Kordula , Bickel-Sandkötter Susanne , Rodriguez-Valera Francisco
Published: August 2018

Both, Haloferax mediterranei and Haloferax volcanii membranes contain ATPases which are capable of hydrolyzing ATP in presence of Mg2+ or Mn2+. The ATPases require high concentrations of NaCl, a pH value of 9, and high temperatures up to 60 °C. Free manganese ions inhibited the enzyme activity of either ATPase. The ATPases of Hf. mediterranei and Hf. volcanii, respectively, show different sensitivities to inhibitors of ATP hydrolysis. ATP hydrolysis of isolated Hf. mediterranei ATPase was inhibited by NaN3, which was reported to be specific for F-ATPases, by nitrate and N-ethylmaleimide (NEM), which are specific inhibitors of V-ATPases. ATP hydrolysis of Haloferax mediterranei membranes was not inhibited by DCCD , but [14C]DCCD was bound to a 14 kDa peptide of the isolated, partially purified enzyme. Furthermore, the ATPase was inactivated by preincubation with 7-chloro-4-nitrobenzofurazan (NBD-Cl). The ATPase activity of Hf. volcanii membranes was inhibited by NEM but not by nitrate and NaN3. SDS gel electrophoresis of the partially purified enzyme of Haloferax mediterranei showed putative ATPase subunits of 53.5, 49, 42, 22, 21, 14, 12, and 7.5 kDa. Immunoblots showed cross reactivity between a 53 kDa peptide and anti-β (chloroplast F1), as well as between 53, 50 and 47 kDa peptides and an ATPase antibody of Methanosarcina barkeri. The results will be discussed in context with the placement of the archaebacterial ATPases (A-ATPases) between F- and V-ATPases
A New Triterpene Acid From The Fern Notholaena Grayi
Authors: Arriaga-Giner F. J. , Bruix Marta , Wollenweber E.
Published: August 2018

In addition to several previously reported flavonoid aglycones, the white farinose material accumulating on the lower leaf surface of Notholaena grayi contains as major constituent a triterpene. This product has now been identified by detailed NMR spectroscopic studies as the novel (24R)-3ɑ, 24,25-trihydroxylanost-9(11)- en-28-oic acid
Spontaneous Bumps Of The Limulus Photoreceptor Cell Are Probably Triggered By The Spontaneous Activation Of Single G-Protein Molecules
Authors: Reuß Helmut , Rack Michael , Stieve Hennig
Published: August 2018

The elementary responses, the “bumps”, of the ventral photoreceptor of Limulus polyphemus were studied under voltage clamp conditions. We compared spontaneous bumps with those induced by light and we applied the G-protein activator A1F4
-. The amplitude of the spontaneous bumps is on the average 7 - 8 times smaller than that of the light-induced bumps. Bumps induced by A1F4
- have identical size and time parameters when compared with spontaneous bumps. Thus at least a large part of the spontaneous bumps is probably triggered by the activation of single G-protein molecules. However, if the next step of the transduction chain is gainless, it is also possible the spontaneous bump originate from this step. The different size of spontaneous and light-induced bumps can be explained assuming that a light-activated metarhodopsin molecule leads to the activation of 3 to 12 G-protein molecules
Odor-Structure Relationships in n-Hexenols and n-Hexenais
Authors: Hatanaka Akikazu , Kajiwara Tadahiko , Horino Hiroshi , Inokuchi Kenichi
Published: August 2018

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

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

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.
Analysis of Phenolics of Bud Exudate of Populus tristis by GC/MS
Authors: English S. , Greenaway W. , Whatley F. R.
Published: August 2018

Analysis of bud exudate of Populus tristis by GC/MS revealed 61 phenolic components representing 55 phenolic compounds. Caffeic acid esters and chalcones made up the bulk of the exudate.
Isolierung und Strukturaufklärung von Bartramia-Triluteolin, Bartramiasäure und einigen Biflavonoiden aus dem Laubmoos Bartramia pomiformis / Isolation and Structure Elucidation of Bartramia-Triluteolin, Bartramic Acid and Biflavonoids from the Moss Bartramia pomiformis
Authors: Seeger Tassilo , Geiger Hans , Zinsmeister Hans Dietmar
Published: August 2018

From Bartramia pomiformis bartramic-acid (luteolin-8,2′′-protocatechuic acid), bartramiatriluteolin, the first triflavone and six known biflavonoids (bartramiaflavone, anhydrobartramiaflavone, 2,3-dihydrophilonotisflavone, philonotisflavone, dicranolomin and 5′,3′′′-dihydroxyamentoflavone) could be isolated. The structures of the new compounds were elucidated spectroscopically.
Localization of Prenylated Flavonoids in Sophora flavescens var. angustifolia Plants
Authors: Yamamoto Hirobumi , Ichimura Masahiko , Ishikawa Noriko , Tanaka Toshiyuki , Iinuma Munekazu , Mizuno Mizuo
Published: August 2018

A histochemical analysis was carried out on the distribution of flavonoid derivatives in Sophora flavescens var. angustifolia plant. Prenylated flavonoids such as kushenol I, kurarinone, sophoraflavanone G and des-O-methylanhydroicaritin were mainly localized in the periderm (cork layers, and cork layer-like tissues scattered in parenchymatous tissues of the root system). Pterocarpan derivatives, maackiain, maackiain-3-O-glucoside (trifolirhizin) and its 6′-O-malonyl ester, were distributed in the cortex, cambium and pith as an ester form. In the aerial parts of the plant, neither pterocarpan nor prenylated flavonoid derivatives, but only flavone monoglucosides such as luteolin-7-O-glucoside and apigenin-7-O-glucoside were detected.
Degradation of Pentachlorophenol by Mycena avenacea TA 8480 - Identification of Initial Dechlorinated Metabolites
Authors: Kremer Stefan , Sterner Olov , Anke Heidrun
Published: August 2018

Cultures of the basidiomycete Mycena avenacea TA 8480 were shown to metabolize entachlorophenol (PCP), 2,3,5,6-tetrachloro-p-hydroquinone (TeCHQ), and 2,3,5,6-tetrachloro-p- benzoquinone (TeCBQ). The first metabolite of the PCP degradation pathway was identified as TeCBQ which in a second reaction is reduced to the hydroquinone TeCHQ. Subsequently dechlorination of TeCHQ yielded 3,5,6-trichloro-2-hydroxy-p-benzoquinone (TCOHBQ). The specific degradation rate for PCP was 1.4 mg x g dry m ycelia-1 x day-1. The initial dechlorination rate of TeCHQ was 5.9 mg x g dry mycelia-1 x hour-1. None of the compounds supported growth of the fungus.
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
Amines in the Marking Fluid and Anal Sac Secretion of the Tiger, Panthera tigris
Authors: Banks Glyn R. , Buglass Alan J. , Waterhouse John S.
Published: August 2018

Analysis of the marking fluid of two tigers (one Bengal and one Sumatran) by GC using an amine-specific column and a nitrogen-specific detector has shown the presence of the following amines: ammonia, methylamine, dimethylamine, trimethylamine, triethylamine, propylamine, and butane-1,4-diamine (putrescine). In contrast to previously published reports, we were unable to detect 2-phenylethylamine. The anal sac secretion was found to have a similar amine content.
Substrate Specificity of Tea Leaf Hydroperoxide Lyase
Authors: Hatanaka Akikazu , Kajiwara Tadahiko , Matsui Kenji , Toyota Hiromitsu
Published: August 2018

Substrate specificity of tea leaf fatty acid hydroperoxide lyase was systematically investigated using an entire series of ω 6-(5)-hydroperoxy-C14-C24 dienoic and trienoic acids as substrates. Unexpectedly, the hydroperoxides of C22 but not natural substrates, i.e., those of C18, showed the highest reactivities for the lyase. The reactivities of the hydroperoxides of trienoic acids were always four to ten times higher than those of the dienoic acids.
Red Blood Cell Partitioning of the [6 S]- and the [6R]-Isomer of N5-Formyltetrahydrofolic Acid
Authors: Czejka Martin J. , Schüller Johann , Scheithauer Werner
Published: August 2018

The in vitro interaction of the [6S]- and [6R]-stereoisomers of CHO-THFA with human RBCs was investigated in the (therapeutically comparable) concentration range from 1.0 to 12.5 μg/ml. Both compounds are bound to RBCs with a kRBC ranging from 0.13 to 0.75 for [6S]-CHO-THFA and from 0.06 to 0.33 for [6R]-CHO-THFA, respectively. The interaction of the [6S]-form with RBCs is about two times higher than of the [6R]-form. Incubation of CHO-THFA with RBCs over 24 h showed an accelerated disappearance from the test solution for [6R]-CHO-THFA with a mean t1/2 of 49.9 h in compare to t1/2 = 58.2 h for the [6S]-enantiomer. The results indicate that RBCs may play a major role for the pharmacokinetics and metabolism of CHO-THFA and may act as an intravasal depot especially for [6S]-CHOTHFA.
Micromorphometric Evaluation of Changes in Symmetry of Sarcoplasmic Reticulum Membranes Induced by Vanadate
Authors: Kranzhöfer Kristine , Agostini Bruno , De Martino Luisa , Hasselbach Wilhelm
Published: August 2018

Electron micrographs of light sarcoplasmic vesicles fixed with glutaraldehyde and osmium tetroxide followed by contrasting with uranyl acetate and lead citrate have been evaluated by registering their membrane profiles with a microdensitometer. The asymmetric arrangement of the two layers of the vesicular membrane could be ascertained by demonstrating a ratio of 1.5 for the thickness of the outer versus the inner membrane layer which is in general agreement with the proposed protein structure of the calcium transport enzyme. Treatment of the vesicles with low concentrations of vanadate (0.1 mM) results in a significant lowering of the symmetry ratio by 20% by reducing mainly the thickness of the outer membrane leaflet. Removal of the membrane lipids by treating the vesicles with phospholipase A2 and bovine serum albumin diminishes the membrane surface by 50% resulting in a significant increase of both the membrane thickness and the asymmetry ratio by 30 and 12% respectively. The vanadate induced reduction of membrane asymmetry is accentuated after delipidation indicating that the membrane lipids are not essential for the asymmetric appearance of the native membrane. The stability of the spherical form of the vesicles to delipidation implies that the transport molecules are conically shaped allowing strong mutual interactions. At a measured height of the molecule of 80 Å in the membrane, the vanadate induced change in symmetry would be brought about by compensatory changes of less than 3 Å of the outer (35 Å) and the inner (25 Å) diameter of the cone.
5-Hydroxyaloin A in the Genus Aloe Thin Layer Chromatographic Screening and High Performance Liquid Chromatographic Determination
Authors: Rauwald Hans W. , Beil Anette
Published: August 2018

By a comparative thin layer chromatographic screening of the methanol-soluble leaf exudates from more than 400 Aloe plants (183 species), 5-hydroxyaloin A was identified in 20 species. Whilst 13 of the 20 species revealed interindividual variations concerning to the occurrence of 5-hydroxyaloin A, this anthrone-C-glucosyl was unambiguously detected in each individual of 6 Aloe species. In the leaf exudates from A. marlothii Berger 5-hydroxyaloin A was only traceable in the aloin-containing chemivars. The complete anthrone-C-glucosyl pattern of these 7 clearly characterized species has been determined additionally by qualitative and quantitative high performance liquid chromatography: The results obtained demonstrate that 5-hydroxyaloin only occurs in the more stable A-configuration (10 R, 1′S), thus being till now the only anthrone-C-glycosyl which has not been found as diastereomeric pair genuinely in plants. As well, 5-hydroxyaloin A characterizes a quantitatively significant hydroxylating pathway in biosynthesis of anthranoids. It is discussed as a chemotaxonomic marker of the genus Aloe, especially of the sections Pachydendron and Eualoe.
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

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

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.
Diurnal Fluctuations of Cocaine and Potential Precursors in Leaves of Erythroxylum coca
Authors: Johnson Emanuel L.
Published: August 2018

Cocaine is abundant in leaves of Erythroxylum coca var. coca Lam. Consequently, cocaine and two of its early biosynthetic precursors were monitored for 24 h to determine whether they fluctuated diurnally. E. coca was grown under controlled environmental conditions in a growth chamber in soil at pH 3.5. After 17.5 months of growth, leaves not less than 35 days old were harvested every 2 and 4 h for 24 h for arginine, phenylalanine and cocaine content, respectively. The content of cocaine was determined by GC/MS and amino acid content by HPLC. Diurnal fluctuation of cocaine occurred during the 24 h cycle. Cocaine was highest in leaves of E. coca at 8 and 16 h where its content was 7.67 and 9.45 mg·g-1 dry weight, respectively. Arginine and phenylalanine in leaves of E. coca also displayed diurnal rhythmic patterns of fluctuation. The content of arginine declined from hours 6 to 12 and increased to the highest content at 13 h (21.8 mg·g-1 dry weight). Overall, phenylalanine content was lower than arginine, but had two peak periods of accumulation during the 24 h cycle, occurring at 8 and 14 h. The content of phenylalanine in leaves of E. coca during the peak hours was 6.98 and 6.54 mg·g-1 dry weight, respectively.
Modification of Histidine Residues of Photosystem II by Diethyl Pyrocarbonate Inhibits the Electron Transfer between the Primary (QA) and Secondary (QB) Quinone Acceptors
Authors: Hegde U. , Padhye S.
Published: August 2018

The effect of diethyl pyrocarbonate (DEPC) on the photosynthetic electron transport was investigated in isolated spinach thylakoids by partial electron transport rate and thermolumi- nescence measurements. Incubation of thylakoids at pH 6.5 with 5 mм DEPC for 15 min resulted in a considerable inhibition of electron transport from water to dichlorophenolindo- phenol. The inhibition was only partially releaved by addition of the donor, diphenylcarbazide indicating the effect of DEPC both on the donor and acceptor sides of PS II. In the thermoluminescence glow curve DEPC-treatment abolished the B band (S2QB
- radiative charge recombination) at 30 °C with a concomitant appearance of the Q band (S2QA
- charge recombination) at 10 °C. This suggests that in isolated thylakoids possessing an active water-splitting system DEPC affects the electron transfer from QA to QB but does not inhibit the electron transport from manganese to QA during the S,→S2 transition of the water-splitting system. At the acceptor side of PS II the targets of DEPC are probably the histidines which are coordinated to the non-heme iron. Illumination of thylakoids at -80 °C following DEPC addition after two preflashes at 5 °C resulted in the replacement of the A(AT) thermoluminescence band at -30 °C with a band appearing at -15 °C. This observation can be explained by the effect of DEPC on a donor side histidine component participating in the generation of the A(AT) band. Consequently, in the interpretation of results obtained by DEPC treatment of PS II, both the donor and acceptor side effects of DEPC should be considered.
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

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

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.
Mutational Analysis of the PsbL Protein of Photosystem II in the Cyanobacterium Synechocystis sp. PCC 6803
Authors: Anbudurai P. R . , Pakrasi Himadri B.
Published: August 2018

The psbL gene is a member of the psbEFLJ gene cluster in the cyanobacterium Synechocystis sp. PCC 6803 and higher plants. psbL, a 4.5 kDa protein encoded by this gene, is a component of the photosystem II complex. The amino acid sequence of this protein indicates that it has a single membrane-spanning a-helical domain. We have used a targeted mutagenesis technique to delete the coding region of the psbL gene in Synechocystis 6803. The resultant mutant strain T345 did not show any PSII-mediated oxygen evolution activity and, as a result, could not grow under photoautotrophic conditions. However, it had normal PSI activity. The chlorophyll to phycobilin ratio in the T345 cells was significantly lower than that in the wild type cells. Fluorescence emission spectra (77 K) of the mutant cells showed the absence of a 695 nm band that usually originates from the PSII complex. Binding assays with radioactive diuron demonstrated that the mutant cells did not have any herbicide binding activity. However, immunostaining experiments showed that both the D 1 (the herbicide binding protein) and the D 2 proteins of the PSII reaction center were present at > 25 % of their normal levels in the thylakoid membranes of the T345 mutant cells. Our data indicate that the PsbL protein is essential for the normal functioning of PSII.
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

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.
Localization of Target-Site of the Protoporphyrinogen Oxidase-Inhibiting Herbicide, S-23142, in Spinacia oleracea L.
Authors: Che Fang-Sik , Takemura Yoko , Suzuki Naoko , Ichinose Katsunori , Wang Jim-Ming , Yoshida Shigeo
Published: August 2018

Effects of S-23142 on protoporphyrin IX (Proto IX) biosynthesis in chloroplasts isolated from Spinacia oleracea L. were examined using reverse phase HPLC with fluorescence monitoring. The synthesis of Proto IX was inhibited to a level of 50% by 10-9 ᴍ of S-23142 in this system. The effects of S-23142 was also tested in chloroplasts isolated from two types of photomixotrophic tobacco cells, wild type and S-23142 tolerant cells. The biosynthesis of both the wild type cells and YZI-1 S cells were inhibited at 50% by 10-9 ᴍ and 10-7 ᴍ of S-23142, respectively. It is, therefore evident that the mutation in the tolerant cell is associated with the Protox. To investigate the localization of Proto IX biosynthesis and the target site of S-23142, spinach chloroplasts were osmotically broken and separated into stroma and membrane (thylakoid and envelope) fractions. A very active Proto IX synthesis from ALA was found in the stromal fraction, while no activity of Proto IX synthesis was observed in the membrane fraction. These results suggest that most Proto IX synthetic activity and a target-site of S-23142 exist in the stromal fraction.
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.
Chlorophyll Fluorescence Applied in the Analysis on Vertical Movement of Herbicides in Soil
Authors: Yanase D. , Andoh A. , Chiba M , Yoshida S.
Published: August 2018

Five photosynthesis inhibiting herbicides were compared for their mobility in soil columns used as the penetration model. The vertical movement of these compounds in soil was analyzed by a newly developed technique in which herbicide distribution was determ ined by the intensity of chlorophyll fluorescence in Chlorella cells suspended in aqueous extracts of soil samples from various depths. With the aid of a fluorescence microplate scanner, measurement of chlorophyll fluorescence was performed with great efficiency. Photosynthesis inhibiting activity of tested herbicides was determined beforehand by the same method and served in calculating herbicide concentrations in sample extracts. Among tested compounds, hexazinone showed the greatest mobility and diuron the smallest, suggesting water solubility is one of the factors which govern the soil mobility of herbicides.
Asymmetrie Reduction of Synthetic Ketones by Marine Microorganisms
Authors: Yamazaki Yoshimitsu , Maruyama Akihiko , Hosono Kuniaki , Higashihara Takanori , Kobayash Harumi
Published: August 2018

Three strains of bacteria reducing (trifluoroacetyl)ferrocene (3) to optically pure (R)-2,2,2-trifluoro-l-hydroxyethylferrocene (4) and one bacterial strain reducing 3 to (S)-4 of moderate optical purity were isolated from sea-water collected at the coastal areas in Ibaraki prefecture of Japan. The former three strains were identified as Micrococcus lylae, Micrococcus luteus, and Deleya marina and the latter as Bacillus licheniformis. These strains also asymmetrically reduced some other synthetic ketones, e.g., 2,2,2-trifluoroacetophenone (7) and phenyl trimethylsilyl ketone (9). Further screening of microorganisms capable of reducing 3 was done with bacteria isolated from sea-water of the deep sea (Okinawa trough, Japan trench, and Mariana trough) and of the pelagic areas (Indian Ocean and South China Sea). Most of these marine strains preferentially reduced 3 to (R)-4 similar to the coastal strains, but the frequency of finding very highly enantioselective strains (i.e., those forming 4 of > 90% e.e.) was remark­ ably high in several sites of the deep sea and pelagic areas as compared with the coast and terrestrial environment.
Molecular Modelling of the Interactions between Optically Active Triazine Herbicides and Photosystem II
Authors: Mackay Simon P. , O' Malley Patrick J.
Published: August 2018

The QB binding site of photosystem II in green plants displays stereoselectivity for the (S′) stereoisomer of the α-methylbenzyl derivative of atrazine but not for derivatives with smaller substituents such as sec-butyl. We have shown that interactive models reflect the experimental data by determining the intermolecular energies between the D1 protein binding region (resi­dues Leu 210 to Val 280) and the triazine analogs. The intermolecular energy was calculated by van der Waals and electrostatic interactions after energy minimization of the combined structures to reduce inter and intramolecular strain. On the basis of these assumptions the role of stereoselectivity for optically active triazines was site responsible such stereoselectivity was identified.
Photoproduction of Hydrogen by Purple Bacteria: A Critical Evaluation of the Rate Limiting Enzymatic Steps
Authors: Klemme J.-H.
Published: August 2018

The enzymatic mechanisms and energetics of nitrogenase-catalyzed photoproduction of hydrogen from organic C-compounds by purple bacteria are discussed in respect to the question of which of the following three enzymes or enzyme systems are rate limiting for H2-production: (a) the nitrogenase-complex; (b) the enzymes and electron transport proteins involved in hydrogen transfer from the organic substrate(s) to nitrogenase; and (c) the system of photosynthetic ATP-regeneration. Calculations of maximum in vivo rates of photosynthetic ATPregeneration (gATP-values derived from growth rates), and of ATP-consumption by nitrogenase- catalyzed H2-production, and comparison of these rates with the specific activities of the enzymes of hydrogen or electron transfer from the C-substrate to the nitrogenase-complex, make it very likely that, in Rhodospirillum rubrum, nitrogenase-catalyzed H2-formation is limited by the availability of ATP and, possibly, of reducing power. In two other nonsulfur purple bacterial species (Rhodobacter capsulatus and Rhodobacter sphaeroides), H2-photoproduction is probably not energy-limited.
Spin Label Study of Apomembranes and Purple Membranes
Authors: Lazarova Tzvetana R. , Velitchkova Maya Y.
Published: August 2018

Three spin-labelled fatty acids were used to detect the dynamics of lipid bilayer of apomem branes and purple membranes. It was found that ESR spectra of spin labels bound to apo­ membranes showed a temperature-induced changes rather similar to those seen with purple membranes. At the same time, however, the values of hyperfine splitting parameter 2Tm were lower as compared to purple membranes. The results pointed out that the removal of the retinal from purple membranes affects the dynamics of lipid bilayer and apomembranes were more rigid structure than those of purple membranes.
Monte Carlo Simulation of Shot Noise Analysis for Reconstructing Elementary Events: Quantum Bumps in Photoreceptor Cells
Authors: Joeken Stephan , Schnakenberg Jürgen
Published: August 2018

Shot noise analysis is a frequently applied method for reconstructing elementary events from experimental data of noisy signals. The subject of this paper is the reconstruction of single photon responses in photoreceptors, the so-called quantum bumps, from experimental data which have been obtained at high light intensities where the quantum bumps can no longer be observed as individual events. The application of this method requires some basic prerequisites which are very likely not satisfied in photoreceptor cells. This situation makes the results of the method questionable. In order to estimate the reliability of shot noise reconstruc­tion in photoreceptors we directly compare the reconstruction results with well known input parameters by using a simulation model for the elementary mechanisms in the cell membrane which cause the response to light stimulation. The comparison shows that the reconstruction method starts to yield errors already at low intensities if only a few percent of the light con­ trolled ionic channels in the cell membrane are open on average. The errors of the method become about 100 percent in the light intensity regime between 10 percent open channels and the onset of bump speck contact on the membrane. The anticipation that the reconstruction method yields single channel events at high light intensities is disproved at least for physiologi­cally realistic intensities.
Das Biflavonoidmuster des Laubmooses Bartramia halleriana / The Biflavonoid Pattern from the Moss Bartramia halleriana
Authors: Salm Rudolf , Seeger Tassilo , Zinsmeister Hans Dietmar
Published: August 2018

From the moss Bartramia halleriana six biflavonoids have been isolated. Their structure was elucidated by chromatographic and spectroscopic methods. The compounds are bartramiaflavone, anhydrobartramiaflavone, philonotisflavone, 2,3-dihydrophilonotisflavone, 5′,3‴-dihydroxyamentoflavone and 5′,3‴dihydroxyrobustaflavone.
Exudate Flavonoids from Grindelia tarapacana of Chile
Authors: Wollenweber Eckhard , Dörr Marion , Timmermann Barbara N. , Strand Jennifer , Fuentes EduardoR.
Published: August 2018

Ten methylated flavonols have been identified in the lipophilic resinous exudate found on aerial parts of Grin­ delia tarapacana, a gum weed species of Chile.
Identification and Cytogenetic Analysis of an Abnormal Pig Chromosome for Flow Cytometry and Sorting
Authors: Hausmann Michael , Popescu C. Paul , Boscher Jeannine , Kerboœf Dominique , Dölle Jürgen , Cremer Christoph
Published: August 2018

For cytogenetics of pig (Sus scrofa domestica) and the influence of chromosome aberrations on pig production, high interest exists in flow sorted chromosomes for gene mapping, to estab­lish DNA-libraries, or to produce DNA-probes. Flow karyotyping and sorting as well as slit scan flow analysis of metaphase chromosomes of an abnormal cell type carrying a translocation marker chromosome 6/15 are described. Flow sorting of the largest chromosomes of these cells was performed. After sorting the chromosomes still had a well preserved morphology and were identified microscopically by G-banding. The quality of the band pattern of the sorted chromosomes was compatible to that of isolated chromosomes not subjected to flow cytometry. The sorted fraction showed an enrichment of chromosom e 6/15 and chromosome 1 which have quantitatively about the same integrated fluorescence intensity. Slit scan flow analysis was performed to discriminate these two chromosomes. Metacentric and submetacentric chromosom es were analyzed according to their bimodal slit scan profiles. Profiles of the largest chromosomes were distinguished by their different centromeric indices. Two groups were interpreted as the normal chromosome 1 and the translocation chromosom e 6/15.
Quinolizidine Alkaloid Profiles of South American Lupins: Lupinus linearis and the Lupinus gibertianus Complex
Authors: Planchuelo-Ravelo Ana , Witte Ludger , Wink Michael
Published: August 2018

The alkaloid composition of leaves of Lupinus linearis Desr. (3 ecotypes) and L. gibertia­ nus Smith (6 ecotypes) from Argentina and Brazil were studied by capillary gas-liquid chromatography and GLC-mass spectrometry (EI-MS). Both species are closely related according to morphological criteria. This view is supported by the alkaloid profiles which are very similar and share a series of new and uncommon alkaloids. Main alkaloids are lupanine, 13-hydroxylupanine, esters of 13-hydroxylupanine (e.g. 13-angeloyloxylupanine, 13-tigloyloxylupanine, 13-benzoyloxylupanine, 13-cis/trans-cinnamoyloxylupanine). Minor alkaloids are: sparteine, 11,12 -dehydrosparteine, ammodendrine, tetrahydrorhom bifoline, angustifoline, α-isolupanine, 5,6-dehydrolupanine, 11,12-dehydrolupanine, N-formylangustifoline, 13-cis-cinnamoyloxymultiflorine. New minor alkaloids which have been tentatively identified by GLC-MS are 13-hydroxy-17-oxolupanine and corresponding esters (13-an-geloyloxy-17-oxolupanine, 13-tigloyloxy-17-oxolupanine, 13-benzoyloxy-17-oxolupanine, 13-cis-cinnamoyloxy-17-oxolupanine, and 13-trans-cinnamoyloxy-17-oxolupanine).
6β-Hydroxylation of 17α-Acetoxycortexone by Flavobacterium
Authors: Spassov Grigor , Abraham Wolf-Rainer
Published: August 2018

Fermentation of a mixture of 3,17α,21-triacetoxy-3,5-pregna-diene-20-one and 17α ,21- diacetoxy-4-pregnene-3,20-dione with Flavobacterium dehydrogenans ATCC 13930 led to 17α-acetoxy-21-hydroxy-4-pregnene-3,20-dione as the main product and the novel 17 aacetoxy- 6β,21-dihydroxy-4-pregnene-3,20-dione and 17α-acetoxy- 6α ,21-dihydroxy-4-pregnene- 3,20-dione as the minor ones. 6 -Hydroxylation was not found so far with this strain. The finding is in good accordance with the model of 6 -hydroxylation of steroids proposed for fungi by Holland et al
The Unexpected Reduction of the Vinyl Group of Chlorophyll b by Sodium Borohydride in Methanolic Extracts of Maize Leaves and Its Inhibition by 8-Hydroxyquinoline
Authors: Porra R. J. , Schäfer W. , Cmiel E. , Katheder Ingrid , Scheer H.
Published: August 2018

During rapid extraction of chlorophylls from maize leaves under reducing conditions with methanol containing NaBH4, chlorophyll a remained unchanged but chlorophyll b yielded [7-hydroxymethyl]-chlorophyll b. The 3-vinyl group of chlorophyll b was also reduced forming significant am ounts, up to 60%, of [3-ethyl]-[7-hydroxymethyl]-chlorophyll b. This was unexpected since this reduction of the 3-vinyl group does not occur when isolated chlorophyll b is treated in an identical manner with methanolic borohydride. The vinyl-group of chlorophyll a is not reduced during the same extraction conditions suggesting that the presence of a formyl or hydroxyethyl group at C-7 is necessary. The presence of 8-hydroxyquinoline and NaBH4 in equimolar (16.5 m M) concentrations strongly inhibits the reduction of the 3-vinyl group of chlorophyll b in leaf extracts