bluuebunny/crossref_metadata_2025 huggingface dataset:
Sequestration, N-Oxidation and Transformation of Plant Pyrrolizidine Alkaloids by the Arctiid Moth Tyria jacobaeae L
Authors: Ehmke Adelheid , Witte Ludger , Biller Andreas , Hartmann Thomas
Published: August 2018

Larvae of the arctiid moth Tyria jacobaeae reared on Senecio jacobaea or S. vulgaris take up and store pyrrolizidine alkaloids (PAs) from their host plants. Individual PAs are taken up without preference. The PA patterns found in the insect bodies correspond to the PA composi­tion of their host plants. Like plants the insects store PAs as N-oxides, and larvae as well as pupae are specifically able to N -oxidize any tertiary PA. Callimorphine (O9-(2-methyl-2-acetoxybutanoyl)-retronecine), an insect PA well known from several arctiids, was found in pupae and imagines of Tyria which as larvae had been fed on S. jacobaea. It is accompanied by small amounts of its isomer O7-(2-methyl-2-acetoxybutanoyl)-retronecine named isocallimor-phine. The callimorphines may well account for 45% of total PAs found in the insect. Only small amounts of callimorphine were detected in pupae of Tyria which as larvae had been fed on S. vulgaris. [14C]Callimorphine N -oxide was isolated and identified from Tyria pupae which as larvae received [14C]retronecine. It is suggested that Tyria is able to esterify retronecine, derived from hydrolysis of ingested plant PAs with a necic acid produced by the insect. During metamorphosis the formation of callimorphine is restricted to the early stage of pupa­tion.
The Interaction between Hydrogen Peroxide and the DNA -Cu (I) Complex: Effects of pH and Buffers
Authors: Prütz Walter A.
Published: August 2018

Abstract The rate of interaction between H2O2 and the DNA -Cu (I) complex increases with pH and with salt (NaCl) concentration, suggesting that HO2
- is involved. The pH dependence can be fitted, assuming k(DNA - Cu(I) + H2O2) = 1 м -1 s-1 and k (DNA -Cu(I) + HO2
-) = 105 м-1 s-1 (at low salt concentrations). These interactions cause DNA damage, probably due to the for­mation of ·OH radicals near the site of Cu(I) fixation at DNA bases. About 70% of the inter­mediates DNA ·OH , formed by free ·OH radicals, were found capable of reducing Cu(II) to regenerate DNA -Cu (I); thus a (limited) reaction chain involving “reductive propagation” by DNA ·OH species appears feasible upon reaction of H2O2 with DNA -Cu (I). ·OH-induced in­termediates of poly(C) are more efficient (about 80%), those of poly(A) and poly(G) are less efficient (about 38%), in reducing Cu(II). Certain organic buffers, particulary HEPES and PIPES, promote autoxidation in DNA /Cu (II)/H2O2 systems, and it is shown that ·OH-induced buffer intermediates as well as secondary stable buffer products can engage in “reductive propagation” of redox cycles.
Ovipositional Host Plant Preference of Sepia officinalis
Authors: Denucé J. Manuel
Published: August 2018

Abstract The present study was undertaken to verify ancient data in the literature on ovipositional preference of the cuttlefish Sepia officinalis for the terrestrial plant Pistacia lentiscus (mastic tree). -Adult specimens of Sepia were placed in basins together with aerial parts not only of P. lentiscus, but also of Artemisia arborescens, Centaurea alba var. deusta, Quercus ilex and Laurus nobilis. The egg masses deposited on the plants were quantified on a daily basis during the 16 day observation period. By far the largest amounts of eggs were found attached to the stems and petioles of P. lentiscus (51.8%), but Q. ilex and A. arborescens also scored high as ovipositional host plants (23.1 and 20.2% respectively). L. nobilis and C. alba var. deusta ranked very low (3.6 and 1.3% respectively). Considering the extremely divergent shape of the three preferred oviposition substrates, which excludes affinity for a uniform type of plant, the possibility of chemical attraction cannot be ruled out.
Kaempferol Glycosides in Asplenium scolopendvium Newm
Authors: Mizuno Mizuo , Kyotani Yosuke , Iinuma Munekazu , Tanaka Toshiyuki , Kojima Hiroyuki , Iwatsuki Kunio
Published: August 2018

Five kaempferol glycosides in the fronds of Asplenium scolopendrium were isolated . The structures of three novel flavonol glycosides were determined to be kaempferol 3-O -β-D -glucopyranosyl-( 1→3 )-β -D -(2 -O -caffeoyl)glucopyranoside 7 -O -α -L -rhamnopyranoside , kaempferol 3 -O -β -D -glucopyranosyl-(1→3 )-β -D -glucopyranoside 7 -O -α -L -rhamnopyranoside and kaempferol 3 -O -(2 -O -caffeoyl)-β -D -glucopyranoside 7 -O -α -L -rhamnopyranosideby means of spectral data (FAB-M S, 1H-1H, 1H -13C COSY and 1H-13C long range COSY), respectively.
The Essential Oil of Coleonema album (Rutaceae) and of a Photomixotrophic Cell Culture Derived thereof
Authors: Berger R. G. , Akkan Z. , Drawert F.
Published: August 2018

The volatile shoot oil of Coleonema album was found to be composed of monoterpenes, ses­quiterpenes and phenylpropanoids. Heterotrophic and photom ixotrophic callus cultures were established from green parts of the plant. A photom ixotrophic cell line contained a heteroge­neous population of plastids and synthesized an essential oil, which differed qualitatively and quantitatively from the green parts of the intact plant. Substitution of 2,4-D and pCPA by a lower amount of NAA and high kinetin concentrations favoured the formation of essential oil. The heterotrophic callus, when grown on the same nutrient medium, was devoid of any differ­ entiated plastids and of essential oil constituents. Thus, a close correlation of light-induced plastid differentiation and essential oil synthesis was concluded.
Elicitation of ß-l,3-Glucanase and Chitinase Activities in Cell Suspension Cultures of Ascochyta rabiei Resistant and Susceptible Cultivars of Chickpea ( Cicer avietinum)
Authors: Vogelsang Ralph , Barz Wolfgang
Published: August 2018

β-1,3-Glucanase and chitinase activities have been analyzed in cell suspension cultures of an A scochyta rabiei resistant ILC 3279 and a susceptible ILC 1929 cultivar of chickpea (Cicer arietinum) following treatment with an elicitor derived from this fungal pathogen. A facile method to determine both hydrolase activities in the cell culture medium was established. Significantly higher constitutive and elicitor-induced levels of both hydrolase activities were found in the medium of the ILC 3279 cell culture. The release of these enzyme activities is not due to cell lysis, but rather the consequence of a secretion mechanism. The cells of the resistant line contained a 5 times higher level of chitinase activity in comparison to the ILC 1929 cell culture, whereas the latter cells possessed a 3 times higher β -1,3-glucanase activity. The results are interpreted that accumulation of extracellular hydrolase activities may play an important role among the various plant defense mechanisms previously determined for the incompatible interaction between the resistant cultivar and its fungal pathogen.
The "Additional Subunit" CF0II of the Photosynthetic ATP-Synthase and the Thylakoid Polypeptide, Binding Ferredoxin NADP Reductase: Are they Different?
Authors: Meyer Helmut E.
Published: August 2018

Evidence is presented to support the notion that the 16 kDa thylakoid polypeptide, called CF0II, is an essential subunit of the photosynthetic ATP-synthase complex CF0CF1: It is co-isolated with the other subunits of CF0CF1 in preparations either using octylgluco- side/cholate or Triton X-100. It is co-precipitated by antibodies together with the other CF0CF1 subunits. It is immunochemically not related to thylakoid polypeptides of higher molecular weight nor to some thylakoid polypeptides with similar apparent molecular weight be- tween 16 and 18 kDa: CF1ɛ, CF0I, subunit IV of the b6f complex, the 16.5 kDa peripheral poly- peptide of the oxygen evolving complex of PS II, and the intrinsic ferredoxin NADP reductase binding protein. The N-terminal amino acid sequences of CF0II and the reductase binding protein is determined by Edman degradation and compared: The two sequences arc different and not identical to other characterized thylakoid polypeptides. Monospecific antibodies against CF0II inhibit rebinding of CF1 to EDTA treated thylakoid membranes, H+ efflux from EDTA treated membranes and cyclic photophosphorylation. Thus the additional polypeptide CF0II qualifies for a functional subunit of the photosynthetic ATP-synthase.
The 5.6-Kilodalton Protein in Isolated Chlorosomes of Chloroflexus aurantiacus Strain Ok -70-fl is a Degradation Product
Authors: Griebenow Kai , Holzwarth Alfred R. , Schaffner Kurt
Published: August 2018

Chlorosomcs containing BChl a790 have been isolated from Chloroflexus aurantiacus on sucrose density gradients using the detergents Miranol. Deriphat. N.N-dimethyldodecyl- aminc-N-oxidc, and dodecyl-p-D-rnaltoside. All freshly prepared samples cither lack the poly- peptide of approximately 5 kDa. which appears identical with the 5.6-kDa protein previously assigned the role of BChl c-binding [R. G. Feick and R. C. Fuller. Biochemistry 23, 3693- 3700 (1984)]. or they contain only a minor amount thereof. This polypeptide accumulates in the chlorosomcs in vitro at room temperature within 24 h after isolation. The reaction cannot be prevented simply by addition of the protease inhibitors benzamidinc. F.-caproic ac|d. and phenylmethylsulfonyl fluoride. However, upon denaturation, as required lor gel electrophore- sis, of the freshly isolated chlorosome sample the formation of the 5-kDa polypeptide is inhibit- ed. We conclude that this species, viz. 5.6-kDa protein, is a degradation product of another - as yet unidentified - protein present in the chlorosome preparations. Despite the pronounced proteolytic activity which affords the 5-kDa fragment, the native absorption and fluorescence properties of BChl c and BChl a arc essentially not changed in these chlorosome preparations.
Oviposition Deterrent from Larval Frass of Spodoptera littoralis (Boisd.)
Authors: Klein Birgit , Schildknecht Hermann , Hilker Monika , Bombosch Siegfried
Published: August 2018

A synthetic mixture containing 1-indanone, 2-pentanone, 2-methyl-3-pentanone, 3-mcthyl- 2-pentanone, 2-methylcyclopentanone. 1-hydroxy-propanone. acetophenone, benzaldehyde. n-nonanal, n-decanal, nerolidol, eugenol, thymol, carvacrol and phythol deters oviposition of the Egyptian cotton leaf worm, Spodoptera littoralis (Boisd.). All compounds were identified from larval frass of S. littoralis.
The Kinetics of Hydroxyl-Radical-Induced Strand Breakage of Hyaluronic Acid. A Pulse Radiolysis Study Using Conductometry and Laser-Light-Scattering
Authors: Deeble David J. , Bothe Eberhard , Schuchmann Heinz-Peter , Parsons Barry J. , Phillips Glyn O. , Sonntag Clemens von
Published: August 2018

Hydroxyl radicals were generated radiolytically in N2O -and N2O / O2(4: 1)-saturated aqueous solutions of hyaluronic acid. The hydroxyl radicals react rapidly with hyaluronic acid mainly by abstracting carbon-bound H atom s. As a consequence of subsequent free-radical reactions, chain breakage occurs the kinetics of which has been followed using the pulse radio­ lysis technique.

In the absence of oxygen, strand breakage was followed by the change in conductivity in­ duced by the release of cationic counterions condensed at the surface of hyaluronic acid which is a polyanion consisting of subunits of glucuronic acid alternating with N-acetyl-glucosamine. It appears that strand breakage is not due to one single first-order process, however, the con ­ tributions of the different com ponents cannot be adequately resolved. At pH7 the overall half-life is 1.4 ms, in both acid and basic solutions the rate of free-radical induced strand breakage is accelerated (at pH 4.8, t1/2 = 0.6 ms; at pH 10, t1/2 = 0.18 ms). In the absence of oxygen there is no effect of dose rate on the kinetics of strand breakage.

In the presence of oxygen in addition to conductom etric detection, strand breakage was also followed by changes in low-angle laser light-scattering. These two techniques are complementary in that in this system the conductometry requires high doses per pulse while the light-scat­ tering technique is best operated in the low -dose range. In the presence of oxygen a pro­ nounced dose-rate effect is observed, e.g. at pH 9.7 after a dose of 9.4 Gy the overall half-time is approx. 0.5 s, while after a dose of 6.6 Gy the half-time is approx. 0.23 s. Both the yield and the rate of strand breakage increase with increasing pH, e.g. at pH 7 G(strand breaks) = 0.7 × 10-7 mol J-1 and at pH 10.4, 4.8 × 10-7 mol J-7.

The radiolytic yields of CO2, H2O2, organic hydroperoxides, O2
·- and oxygen consum ption have been determined in y-irradiated N2O/ 0 2(4: 1)-saturated solutions of both hyaluronic acid and β-cyclodextrin.
Fate of Circulating Serotonin in the Hemolymph of the Crayfish, Orconectes limosus
Authors: Hoeger U.
Published: August 2018

The fate of injected [14C]serotonin (0.1 μCi/1.6nmol per animal) was investigated in the crayfish Orconectes limosus after injection. Specific radioactivities reached highest values in the green gland, followed by intestine, gills, nervous tissue and digestive gland. Label accumulation was lowest in the tail muscle.

Cold serotonin injected into the hemolymph (50 nmol/100 g wet wt) was cleared with a mean half life of 12.9 +/- 2.6 min (15°C; N = 5). By HPLC separation of hemolymph samples taken at intervals after the injection of [14C]serotonin, the formation of a metabolic product could be demonstrated. The formation of the metabolite was not, however, detectable by native fluorescence, suggesting the metabolic breakdown of the indole ring. The combined amounts of acid soluble radioactivity recovered from hemolymph, green gland, digestive gland and intestine yielded 80-100%, 50-70% and 30-50% of the injected dose after 7 min, 1 h, and 4 h, respectively. Since other tissues did not account for the balance and less than 5% of the injected label had been excreted into the medium after 4 h the results suggest the gradual incorporation of the metabolites into the tissues
Chemical Constituents of the Lichen Cladina macaronesica
Authors: González Antonio G . , Barrera Jaime Bermejo , Ma Rodríguez Pérez Elsa , Hernández Padrón Consuelo E.
Published: August 2018

Column chromatography of the acetone extract of the lichen Cladina macaronesica (Sephadex LH-20, silica gel and silver nitrate-im pregnated silica gel) afforded eight triterpenes identified by chemical and spectral m eans. α-Amyrenone, lupenone, taraxerol, taraxerone and /so-arborinol acetate were isolated for the first time from lichens and (-)-usnic acid and five mononuclear phenolic compounds were also obtained, four for the first time as natural products. The possible transformation of perlatolic acid into these phenolic compounds is briefly outlined.
Growth and Secondary Product Formation of in vitro Cultures from the Liverwort Reboulia hemisphaerica
Authors: Morais Rui M. S. C. , Becker Hans
Published: August 2018

Reboulia hemisphaerica has been cultivated on Gamborg B5 medium with various sugars. Differentiated cultures grew best on agar medium with the addition of 0.5% sucrose and a light regime of 18 h light/6h dark . Callus was induced either by a combination of phytohor­mones (2 mg/l α-naphthylacetic acid + 1 mg/l kinetin) or by 4% glucose. The differentiated cultures on agar produced sesquiterpenes in a tenfold increased amount compared to undiffer­ entiated suspension cultures. Cultures kept in da rk produced no sesquiterpenes, but 5-hydroxy-7,8,4′-trimethoxyflavone was present whereas apigenin-7,4′-dimethylether was the only flavonoid in cultures cultivated in the light.
Characterization of Pectic Enzymes from the Chickpea Pathogen Ascochyta rabiei
Authors: Tenhaken Raimund , Barz Wolfgang
Published: August 2018

The chickpea pathogenic fungus Ascochyta rabiei when growing in a pectin containing min­eral medium secretes an exo-polygalacturonase (PG) and a pectin methyl esterase into the cul­ture medium. The induction of the PG is controlled by catabolite repression. The PG was puri­fied to apparent homogeneity from the culture fluid by acetone precipitation and chromato­graphy on a Mono S and a Mono Q column. The molecular weight of the purified glycoprotein enzyme in SD S-PAGE was about 70 kDa, whereas the Mr by gelfiltration it was estimated to be 53 kDa. Polygalacturonic acid is the only substrate of the PG whereas pectin is not degraded. The PG releases only galacturonic acid from polygalacturonic acid and no oligogalacturonides which might elicitate chickpea plants and trigger plant defense response. The enzyme is not inhibited by pectin, the released proteins or phenolics.
Omphalone, an Antibiotically Active Benzoquinone Derivative from Fermentations of Lentinellus omphalodes [1]
Authors: Stärk Andreas , Anke Timm
Published: August 2018

Omphalone, a new antibiotic, cytotoxic, and phytotoxic pigment has been isolated from fermentations of a Canadian strain of Lentinellus omphalodes. Its structure has been established as 2-(4-methylfuran-2-yl)-l,4-benzoquinone (1) by spectroscopic investigations and conversion into leuco-acetate 2.
Studies on Porphobilinogen-Deaminase from Saccharomyces cerevisiae
Authors: García Susana Raquel Correa , Rossetti Maria Victoria , del Carmen Batlle Alcira María
Published: August 2018

Porphobilinogen-deaminase from Saccharomyces cerevisiae has been isolated and partially purified 80-and 230-fold in the absence or presence of phenylmethylsulphonyl fluoride, respectively.

Some properties of the isolated enzyme were studied. Porphyrin formation was linear with time and protein concentration. Optimum pH was about 7.5-7.8. Molecular mass of the protein was 30,000 ± 3000 Dalton when the enzyme was purified in the presence of phenylmethyl­ sulphonyl fluoride. A less active and unstable 20,000 Da molecular mass species was obtained when purification was performed in the absence of the protease inhibitor.

Porphobilinogen-deaminase exhibited classical Michaelis-Menten kinetics. The apparent Km for uroporphyrinogen formation was 19 μм; Vmax was 3.6 nmol uroporphyrin/h and the Hill coefficient was n = 1.

Also the action of several reagents on the activity was studied. Protective thiol agents had no effect. Heavy metals inhibited both porphyrin formation and porphobilinogen consumption, but known sulphydryl inactivating chemicals inhibit the former without modifying the latter. Ammonium ions had no effect on the activity while hydroxylamine completely inhibited both porphyrin formation and porphobilinogen consumption.
The Flash Pattern of Photosynthetic Oxygen Evolution after Treatment with Low Concentrations of Hydroxylamine as a Function of the Previous S1/S0-Ratio Further Evidence that NH2OH Reduces the Water Oxidizing Complex in the Dark
Authors: Messinger J. , Pauly S. , Witt H. T.
Published: August 2018

Flash induced oxygen evolution patterns of isolated PS II complexes from the cyanobacterium Synechococcus were measured with a Joliot-type electrode. By suitable preflash and dark adaptation procedures, samples were prepared in the state S1 (100%), as well as enriched in S0 (60% S0, 40% S,). After treatment with low concentrations of NH2OH (≤ 100 μм), the two flash patterns were identical. This is further evidence for a reduction of the water oxidizing complex by hydroxylamine in the dark. Two reduced states (S-1 and S-2) below S0 are formed by this reduction.
Functional Complementation in Escherichia coli of Different Phytoene Desaturase Genes and Analysis of Accumulated Carotenes
Authors: Linden Hartmut , Misawa Norihiko , Chamovitz Daniel , Pecker Iris , Hirschberg Joseph , Sandmann Gerhard
Published: August 2018

Three different phytoene desaturase genes, from Rhodobacter capsulatus, Erwinia uredovora, and Synechococcus PCC 7942, have been functionally complemented with a gene construct from E. uredovora which encodes all enzymes responsible for formation of 15-cis phytoene in Escherichia coli. As indicated by the contrasting reaction products detected in the pigmented E. coli cells after co-transformation, a wide functional diversity of these three different types of phytoene desaturases can be concluded. The carotenes formed by the phytoene desaturase from R. capsulatus were trans-neurosporene with three additional double bonds and two cis isomers. Furthermore, small amounts of three ζ-carotene isomers (2 double bonds more than phytoene) and phytofluene (15-cis and all-trans with + 1 double bond) were detected as inter- mediates. When the subsequent genes from E. uredovora which encode for lycopene cyclase and β-carotene hydroxylase were present, neurosporene, the phytoene desaturase product of R. capsulatus, was subsequently converted to the monocyclic β-zeacarotene and its mono- hydroxylation product. The most abundant carotene resulting from phytoene desaturation by the E. uredovora enzyme was trans-lycopene together with a cis isomer. In addition, bisdehy-drolycopene was also formed. The reaction products of Synechococcus phytoene desaturase were two cis isomers of ζ-carotene and only small amounts of trans-ζ-carotene including 15-cis. The I50 values for flurtamone and diphenylamine to inhibit phytoene desaturation were determined and differential inhibition was observed for diphenylamine.
Uresiphita reversalis (Lepidoptera: Pyralidae): Carrier-Mediated Uptake and Sequestration of Quinolizidine Alkaloids Obtained from the Host Plant Teline monspessulana
Authors: Wink Michael , Montllor Clytia B. , Bernays Elizabeth A. , Witte Ludger
Published: August 2018

Larvae of Uresiphita reversalis feed almost exclusively on legumes of the tribe Genisteae, whose characteristic secondary metabolites are quinolizidine alkaloids (QA). Aposematic larvae store host plant-derived QA in their integument, while the pupae are almost alkaloid-free. In the last instar larvae, alkaloids were concentrated in the larval head, possibly in the silk glands. About 80% of the alkaloids were transferred to the cocoon silk and 19% were lost with larval exuviae.

The larval alkaloid pattern was characterized by capillary GLC and GLC-MS and compared to that of the host plant, Teline monspessulana. Whereas the host plant contained mainly epiaphylline, dehydroaphylline and aphylline, larvae selectively accumulated N-methylcytisine, a relatively minor component of the plant QA; the faeces contained mainly epiaphylline and dehydroaphylline. Thus uptake and sequestration must be selective processes. Uptake by isolated larval midguts was time-, pH- and temperature-dependent and displayed an activation energy between 50 and 80 kJ/mol. Furthermore the in vitro uptake of 13-hydroxylupanine was competitively inhibited by cytisine. All these data provide evidence that QA uptake does not proceed by simple diffusion but instead with the aid of a carrier mechanism; this could explain the differential alkaloid uptake observed in living larvae.
Lepistirones, Major Volatile Metabolites from Liquid Cultures of Lepista irina (Basidiomycotina)
Authors: Abraham Wolf-Rainer , Hanssen Hans-Peter , Urbasch Irene
Published: August 2018

The basidiomycete Lepista irina (F r.) Bigelow (strains CBS 366.47 and CBS 458.79) was cultivated on a biomalt (2% )-liquid medium for 28 days. The steam distillate was analyzed by GLC and GLC-S. The structure elucidation of the predominant constituent resulted from spectroscopic methods, particularly from its 13CNMR spectrum, nuclear Overhauser enhancement 1HNMR data, and from 2d 1H homonuclear shift correlation. The bisabolane derivative was nam ed lepistirone and is described for the first time as a natural product. Two minor related com pounds could be characterized by their MS data.
Time-Course Studies of Phytoalexins and Glucosinolates in UV-Irradiated Turnip Tissue
Authors: Monde Kenji , Takasugi Mitsuo , Lewis Jenny A. , Fenwick G. Roger
Published: August 2018

Sliced turnip root (Brassica campestris L. ssp rapa) was irradiated for a total of 20 min with a 15 W germicidal lamp and the tissue incubated at 25 °C. The effects of such treatment on indole phytoalexins (methoxybrassinin (I); brassinin (II); cyclobrassinin (III); spirobrassinin (IV) and glucosinolates were determined using high performance liquid chromatography procedures. Accumulation of phytoalexins I - III was evident within 8 h of irradiation, whilst formation of spirobrassinin was evident only after 24 h. Maximal levels of III and IV (> 100 μg g-1 freeze dried tissue) were greater than those of I and II (27 and 17 μg g-1, respectively). The individual glucosinolate levels were affected in a complex manner; whilst most glucoinolates decreased on storage, the levels of indole glucosinolates, glucobrassicin (XI) and 1-methoxyglucobrassicin (XIII), increased until 5 to 6 days after irradiation and thereafter declined. Whilst structural features of I - IV , XI and XIII suggest close biosynthetic relationships between these classes of biologically-active indoles, further studies are needed to establish this point unambiguously.
Analysis of Light-Induced Absorbance Changes in the Near-Infrared Spectral Region I. Characterization of Various Components in Isolated Chloroplasts
Authors: Klughammer Christof , Schreiber Ulrich
Published: August 2018

Light-induced absorbance changes in the near-infrared (NIR ) spectral region (700-950 nm) are analyzed in isolated spinach chloroplasts using pulsed light-emitting diodes as modulated measuring light sources. With chloroplasts under coupled conditions the light-induced signal is dominated by a relatively slow scattering change displaying a flat difference spectrum. More specific changes can be distinguished by faster induction and relaxation kinetics and in the presence of valinomycin/nigericin which prevents scattering changes. Besides the dominant P700 change, with a narrow bleaching band around 703 nm and a broad absorbance increase between 750 and 850 nm (peak at 815 nm) the following absorbance changes were identified in the NIR:

1) An absorbance increase caused by plastocyanin (PC) oxidation, with a relatively flat spectrum.

2) An absorbance decrease gaining amplitude towards longer wavelengths, which reflects reduction of a low potential acceptor of PSI different from ferredoxin.

3) A field indicating absorbance decrease peaking around 730 nm, the properties of which correspond to those of P515. 4) An uncoupler insensitive absorbance decrease stimulated by dark adaptation and anaerobic conditions, the difference spectrum of which resembles that of ferredoxin reduction.

The relative contributions of P700 and PC to the overall oxidized-reduced difference spectrum are determined by redox titration. At 706 nm, 815 nm and 950 nm the P 700/PC is - 119/ 19, 67/37 and 31/69, respectively. From these ratios and the molar extinction coefficients a molar P 700/PC stoichiometry of 1 /3 is determined.
Accumulation of the Phytoalexin Glyceollin I in Soybean Nodules Infected by a Bradyrhizobium japonicum nifA Mutant
Authors: Parniske Martin , Fischer Hans-Martin , Hennecke Hauke , Werner Dietrich
Published: August 2018

The mutation of the nifA gene of Bradyrhizobium japonicum leads to a pathogenic-like response of the host plant. Soybean nodules induced by the nifA mutant A9 exhibited symptoms of a hypersensitive reaction (HR) normally observed in plant pathogen interactions as localized death of infected cells and the accumulation of the phytoalexin glyceollin I. Little or no glyceollin I was present in nodules elicited by wild type B. japonicum 110 spc 4.
Novel Bisabolanoids In Rosa Rugosa Leaves
Authors: Hashidoko Yasuyuki , Tahara Satoshi , Mizutani Junya
Published: August 2018

Bisaborosaol A (1), a novel sesquiterpene belonging to the bisabolane class, was isolated from Rosa rugosa leaves. The absolute configuration of 1 at C-4 was shown to be inverted in comparison with bisabolanoids from Compositae. Bisaborosaol A (1) and its corresponding carboxylic acid (2) may be biogenetically related to the carotanoids which constitute the major sesquiterpenes of R. rugosa leaves
Hydroxyphenylpyruvate Reductase From Cell Suspension Cultures Of Coleus Blumei Benth.
Authors: Häusler Elisabeth , Petersen Maike , Alfermann August W.
Published: August 2018

Cell suspension cultures of Coleus blumei Benth. producing high amounts of rosmarinic acid were used to study the biosynthetic pathway of this caffeic acid ester. One of the involved enzymes, the hydroxyphenylpyruvate reductase (HPPR), is characterized in this paper. HPPR catalyzes the NAD (P)H dependent reduction of p-hydroxyphenylpyruvate to p-hydroxyphenyllactate. The enzyme developed maximal activity at an incubation temperature of 37 °C and at a pH of 6.5 to 7.0. The reaction proceeded linearly for an incubation time of 60 min and up to a protein concentration of 0.2 mg per assay. As electron donor HPPR accepted NADH and NADPH with Km-values of 190 µm and 95 µm respectively. The enzyme reduced differently substituted hydroxyphenylpyruvates but not β-phenylpyruvate. The apparent Km-values for the various substrates were at 10 µM for p-hydroxyphenylpyruvate, at 130 µm for 3,4-dihydroxyphenylpyruvate and at 250 µM for 3-methoxy-4-hydroxyphenylpyruvate. HPPR was competitively inhibited by rosmarinic acid and pyruvate with Ki-values of 210 µM and 200 µM respectively. Caffeic acid, p-coumaric acid and cinnamic acid did not affect the enzyme activity but p-coumaroyl-CoA inhibited HPPR
Oligomeric Forms Of Pyruvate Kinase From Chlorella With Different Kinetic Properties
Authors: Ruyters G. , Grotjohann N. , Kowallik W.
Published: August 2018

Fast protein liquid chromatography on Superose 6 of crude extracts from the chlorophyllfree mutant no. 20 of the unicellular green alga Chlorella kessleri reveals two possibly oligomeric forms of pyruvate kinase (2.7.1.40). Their occurrence is markedly altered in the course of heterotrophic growth with changing levels of exogenous glucose as carbon source with only one enzyme species with a MW of 400 kDa existing in growing cells, two forms of 400 and 580 kDa in resting cells. Substrate affinity towards PEP of the 400 kDa form is better than that of the 580 kDa species; responses to the effector AMP are different as well. In vitro, addition of PEP or of AMP leads to the formation of higher MW enzyme species with MW of 730, 1050 and 1400 kDA without affecting the total activity. In vivo alterations in the levels of several metabolites including PEP upon addition of glucose have been shown to occur. Therefore, it is discussed, whether changes in the concentration of intermediates and effectors may provide the mechanism for the increased rate of carbohydrate degradation by affecting the occurrence and/or ratio of the various PK forms with different kinetic and regulatory properties. Upon blue light irradiation, which also stimulates carbohydrate breakdown of the Chlorella mutant cells, the distribution of PK is shifted towards the species with higher substrate affinity, a result being in accordance with the above conception
Podoscyphic Acid, A New Inhibitor Of Avian Myeloblastosis Virus And Moloney Murine Leukemia Virus Reverse Transcriptase From A Podoscypha Species [1]
Authors: Erkel Gerhard , Anke Timm , Velten Robert , Steglich Wolfgang
Published: August 2018

A novel enzyme inhibitor of RNA -directed DNA -polym erases of avian myeloblastosis and murine leukemia virus was isolated from fermentations of an tasmanian Podoscypha species. Its structure was elucidated by spectroscopic methods and oxidative degradation as (E)-4,5- dioxo-2-hexadecenoic acid (1). The enzyme inhibitor, which was named podoscyphic acid, did not inhibit DNA and RNA synthesis in permeabilized L 1210 cells nor did it affect RNA synthesis in isolated nuclei of L 1210 cells. 1 inhibits protein synthesis in whole L 1210 cells and rabbit reticulocyte lysate and shows very weak antimicrobial and cytotoxic properties. The testing of ethyl (E) 4,5-dioxo-2-hexadecenoate (2) and (E)-4-oxo-2-tetradecenoic acid (11) revealed the importance of the free y-oxoacrylic acid unit for the biological activities of 1
Single Photon-Evoked Events Of The Ventral Nerve Photoreceptor Cell Of Limulus Facilitation, Adaptation And Dependence Of Lowered External Calcium
Authors: Stieve H. , Reuß H. , Hennig H. T. , Klomfaß J.
Published: August 2018

Bumps, the elementary excitatory events of the Limulus ventral nerve photo receptor following a weak flash of light were recorded under voltage clamp conditions. The statistical distribution of various bump parameters and their changes caused by weak conditioning pre-illumination are described, and the influence of lowered external Ca2+-concentration together with normal or raised Mg2+-concentration (15 °C).

1) Weak conditioning pre-illumination causes desensitization: the bump current amplitude, bump duration , bump area (current-integral), and the bump latency are diminished, the more, the stronger the conditioning flash, i.e. the light adaptation. Very weak conditioning pre-illumination causes facilitation, expressed by an increase in number and size of the observed bumps. The average bump latency, however, is already shortened under these conditions.

2) Lowering the external Ca2+-concentration from 10 mmol/l to 250 (µmol/1 has its primary effect on the dark -adapted photoreceptor (without substantially reducing the ability for light adaptation ). It causes the following average changes: the amplitudes, durations, current-integrals, and the latencies of current bumps are greatly enlarged and the number of bumps is raised.

3) Raised magnesium concentration from 50 to 100 mmol/l can partially compensate for the lack of calcium ; however, it enhances the effect of calcium deficiency on the latency, i.e. it further enlarges the average latencies. The results can be explained on the basis of our model of bump generation by two assumptions.

1) Lowering the external calcium concentration causes a decrease in the cytosolic Ca2+-level without substantially reducing the intracellular calcium stores from which the light-adapting calcium release is fed. The lowered cytosolic Ca2+-concentration induces an “extra” dark adaptation resulting in greater bumps and more bumps exceeding the threshold of recognition. The bump latency, however, which behaves differently from all other bump parameters, is determined by a separate calcium -dependent reaction where magnesium competes with calcium antagonistically.

2) Facilitation is due to cooperativity of transmitter binding in order to open the ion channels
Squaric Acid Diethylester: A Simple And Convenient Coupling Reagent
Authors: Glüsenkamp K.-H. , Drosdziok W. , Eberle G. , Jähde E. , Rajewsky M. F.
Published: August 2018

A new method for the covalent modification of polymers in a two-step process is described. Squaric acid diethylester reacts with primary or secondary aliphatic amines selectively to ester amides. It is shown for the first time that this class of compounds react with polymeric systems containing amine functionalities (e.g. ε-amino groups of proteins) in aqueous solution, forming stable squaric acid diamide linkages. Three different monoamides were synthesized and the reaction rates of diamide formation versus hydrolysis were determined. Detailed kinetic studies revealed that unwanted hydrolytic side-reactions are more than ten times slower than the formation of squaric acid diamides
Pseudobactin-und Pseudobactin A-Varianten: Neue Peptidsiderophore vom Pyoverdin-Typ aus Pseudomonas fluovescens "E2" / Variants of Pseudobactin and Pseudobactin A: New Pyoverdin Type Peptide Siderophores from Pseudomonas fluorescens "E2"
Authors: Taraz K. , Seinsche D. , Budzikiewicz H.
Published: August 2018

From a strain of Pseudomonas fluorescens pseudobactin and several related compounds were isolated and their structures were elucidated. In this way a reference compound (5) could be obtained for the unambiguous determination of the absolute configuration of C-1 of the pyoverdin chromophore in newly isolated representatives of this class.
A Contact Site between the Two Reaction Center Polypeptides of Photosystem II Is Involved in Photoinhibition
Authors: Trebst A.
Published: August 2018

A new contact site between the two reaction center polypeptides D 1 and D 2 of photosystem II close to arg 238 and arg 234 respectively is proposed. The amino acid sequences involved are between the 4 th transmembrane and a connecting parallel helix. The sequence includes a tryp­ sin sensitive site in both polypeptides, the likely cleavage site in the rapid turnover of the D 1 polypeptide and part of the herbicide binding site. The contact site is oriented towards both quinone binding sites Q A and Q B. A folding of the backbone of the amino acid sequences involved is proposed.
Flüchtige Inhaltsstoffe von Crotalaria ochroleuca und deren Wirkung auf Schadinsekten / Volatile Constituents from Crotalaria ochroleuca and Their Effect on Pest Insects
Authors: Bestmann H. J. , Pietschmann M. , Steinmeier K. , Vostrowsky O.
Published: August 2018

By means of GC -FTIR , GCMS and GC analysis more than 70 components of the steam distillate of seeds and leaves from Crotalaria ochroleuca (Fabaceae, Papilionaceae) were found and partially identified, most of them being aliphatic hydrocarbons, aldehydes and fatty acids. Weak, but significant repellency of the seeds, its steam distillate as well as of the seed oil com ponent 2-isopropyl-3-methoxypyrazine, 2-isobutyl-3-methoxypyrazine and 2-pentylfuran was observed with the curculionid beetle Sitophilus zeamays. Furthermore, no attractivity of fresh leaves was found for a number of test insects.
Basis for Differential Chemical Selectivity of MG-191 Safener against Acetochlor and EPTC Injury to Maize
Authors: Jablonkai Istvan
Published: August 2018

The influence of MG-191 safener on the uptake, translocation and metabolism of [14C]acetochlor and [14C]EPTC was studied. The amounts of absorbed radioactivity by maize seedlings at 3, 6, 24, and 72 h after applications of [14C]labeled herbicides and [14C]MG-191 were different. Plants treated with [14C]acetochlor took up 30-to 50-fold more radiolabel with­in 72 h than [14C]EPTC-or [14C]MG-191-treated plants. Addition of MG-191 caused only mi­nor changes in the rate of herbicide absorption. EPTC and MG-191 and/or their metabolites moved quickly acropetally and partitioned equally between root and shoot tissues up to 72 h. The amount of acetochlor and/or its labeled metabolites translocated to shoot tissues was less than 10%. MG-191 practically had no influence on herbicide translocation rates. With all chemicals the amounts of water-soluble and unextractable fractions increased while the ratio of hexane-extractable metabolites decreased with time. TLC analyses of both water-and hex­ane-soluble metabolites confirmed the fast metabolism of acetochlor. The acetochlor metabo­lism took place via GSH conjugation and more polar, non-conjugated metabolites compared to parent molecule were detected in hexane-soluble fraction. MG-191 enhanced acetochlor metabolism by decreasing the portion of non-metabolized acetochlor. EPTC metabolism re­sulted in water-soluble metabolites having similar chromatographic properties to those of ace­tochlor. However, there was no safener effect on non-metabolized EPTC content of plants. It appears that MG-191 protects maize against EPTC by enhancing the early rate of conjugation with GSH after initial oxidative metabolism.
Metabolism of the Aryloxyphenoxypropanoate Herbicide, CGA 184927, in Wheat, Barley and Maize: Differential Effects of the Safener, CGA 185072
Authors: Kreuz Klaus , Gaudin John , Stingelin Jürg , Ebert Edith
Published: August 2018

The influence of the safener, CGA 185072 (5-chloro-8-quinolinoxy-acetic acid-1-methylhexyl-ester), on the metabolism of the aryloxyphenoxypropanoate herbicide, CGA 184927 (2-propynyl-R-2-[4-(5-chloro-3-fluoro-2-pyridinyloxy)-phenoxy]-propionate), was studied in excised leaves of wheat, barley, and maize. In wheat and barley, CGA 184927 readily under­went ester hydrolysis followed by hydroxylation at the pyridinyl moiety as well as ether cleav­age between the pyridinyl and the phenyl ring. Ether cleavage constituted the minor pathway in both species. All metabolites were subject to glycosyl conjugation. Tetcyclacis strongly in­hibited pyridinyl-ring hydroxylation in wheat. Metabolism by hydroxylation and ether cleav­age was more rapid in wheat than in barley, and was found to be accelerated in the presence of the safener CGA 185072 in both wheat and, to a lesser degree, in barley. Moreover, the safener increased the capacity for O-glycoside formation in wheat as suggested from studies using the ,4C-labelled pyridinyl-ring hydroxylated metabolite as a precursor. In maize, which is highly susceptible to CGA 184927, rapid ester hydrolysis of CGA 184927 and partial conversion of the corresponding carboxylic acid to glycosyl ester conjugate(s) occurred. However, no further transformation of the herbicide was found in maize, both in the absence or presence of CGA 185072. It is concluded that the ability of CGA 185072 to protect wheat from injury by the herbicide, CGA 184927, and to confer partial protection to barley, is related to the ability of the safener to stimulate herbicide metabolism in these crop species.
Effect of the Safener Dichlormid on Maize Peroxygenase and Lipoxygenase
Authors: Blée Elizabeth
Published: August 2018

S-Ethyl-N,N-dipropylthiocarbamate (EPTC) was oxidized into its corresponding sulfoxide by microsomal fractions from etiolated maize seedlings. This reaction is catalyzed by a hydroperoxide-dependent enzyme, identified as a peroxygenase. The hydroperoxides formed from fatty acids by a lipoxygenase are efficient co-substrates of the EPTC sulfoxidation. The effects of the safener dichlormid on the peroxygenase and lipoxygenase activities were studied in vitro and in vivo. In vitro, the safener is not an inhibitor of these enzymes. Dichlormid seems to act, in vivo, by modulating the amounts of peroxygenase and lipoxygenase in treated plants.
Production and Release of Isoflavonoids by Lupin Cell Cultures
Authors: Hallard Didier , Bleichert Ernst , Gagnon Hubert , Tahara Satoshi , Ibrahim Ragai
Published: August 2018

Cell cultures derived from white lupin (Lupinus albus) radicles consist of a mixture of friable cell aggregates and finely divided cells. Both types of tissue accumulate two isoflavonoid aglucones, genistein and 2′-hydroxygenistein, their 7-O-glucosides, and their respective 6-, 8-, and 3′-monoprenyl-, as well as the 6,3′-diprenyl derivatives. Most of these metabolites are differentially released in the culture medium. The relative amounts of aglucones, glucosides and prenylated derivatives that are produced by the aggregates and cells, as well as those excreted into the medium, are discussed in relation to culture growth.
Effect of Salt on the Activity and Stability of Aspartate Aminotransferase from the Halophilic Archaebacterium Haloferax mediterranei
Authors: Muriana Francisco J. G. , Alvarez-Ossorio María C. , Sánchez-Garcés María M. , Rosa Francisco F. de la , Relimpio Angel M.
Published: August 2018

The aspartate aminotransferase from Haloferax mediterranei, which is in the cell mainly as apoenzyme, requires high concentrations of salt for both activity and stability. The maximum activity is reached with 3.5 ᴍ KCl in the assay. The effect of different cations and anions has been studied using several types of salts. Monovalent cations show a significant difference in effectiveness of promoting the activity with the following order: K+ > Rb+ > Na+ > NH4
+. Mg++ and polyvalent cations with organic character cause partial activity with maximum effectiveness at 0.1 ᴍ, an inhibition at higher concentration is observed. Anions, added as potassium salts, promote enzyme activity with the following order: Cl- > NO3
- > I- > SCN-. Like activity, the enzyme stability depends on salt concentrations. Incubation of the enzyme with a low salt concentration leads to inactivation following pseudofirst order kinetics. The inactivated enzyme is partially reactivated by high concentrations of KC1 following second order kinetics. Taking into account the dimeric structure of this enzyme, high concentrations of salt could stabilize the dimer, which is the active form. The salt effects on halophile aspartate am inotransferase are discussed considering hydrophobic and electrostatic interactions.
Study on the Parameters Affecting Oxygen Release Time Measurements by Amperometry
Authors: Schulder R. , Burda K. , Strzałka K. , Bader K. P. , Schmid G. H.
Published: August 2018

The amperometric analysis of photosynthetic oxygen evolution in thylakoid membrane preparations of tobacco, sedimented on a large surface electrode, shows that the oxygen signal is preceded by a lag phase of 1.2 ms. As the used tobacco lamellar systems have an average diameter of 4 - 5 μm this lag phase is interpreted to be due to an average distance of 2.4 μm between oxygen emitting sources and the electrode surface. This interpretation of the lag phase is substantiated by the fact that photosystem I-mediated oxygen uptake in the same preparation measured with the same amperometric technique exhibits the same lag phase although the kinetic uptake parameters are considerably slower than those of oxygen evolution due to the water-splitting reaction. The analysis of the oxygen evolution signal shows that the sedimentation time i.e. the quality of the contact of the source with the electrode is decisive for the measured value for the oxygen release time, which with this method without much effort comes out to be certainly not longer than 1.5 ms. A computer simulation shows that the distance of the oxygen emitting layer from the electrode as well as its thickness and the actual release time are variables which influence practically all parameters (signal shape, amplitude etc.) of such amperometric signals. From this it appears that the determined apparent experimental parameters of oxygen evolution kinetics contain deformations due to the thickness of the sample and the diffusion distance from the electrode. An extrapolation calculated for a sample of infinite thinness separated from the electrode by a minimal distance of 0.001 μm with τ of 5.5 ms yields a lower limit value for the half-rise time of 0.5 ms, a value which has been experimentally determined by EPR oximetry (K. Strzalka, T. Walczak, T. Sarna, and H. M. Swartz, Arch. Biochem. Biophys. 281, 312 (1990)).
Studies on the Chemistry of the Lichen Genus Umbilicaria Hoffm.
Authors: Posner B. , Feige G. B. , Huneck S.
Published: August 2018

The aromatic compounds of more than 400 specimens of 33 species of the lichen genus Umbilicaria have been investigated by HPLC. Additionally to gyrophoric, hiascic, lecanoric, ovoic and umbilicaric acids, atranorin, norstictic and stictic acids, the new depside crustinic acid has been found. Structure elucidation of crustinic acid was made by means of HPLC cochromatography, NMR , UV and mass spectrometry. Now the secondary product patterns of Umbilicaria species are discussed and their significance for systematic purposes is shown.
Modulation of the Activities of Membrane Enzymes by Cereal Grain Resorcinolic Lipids
Authors: Kozubek Arkadiusz , Nietubyc Malgorzata , Sikorski Aleksander F.
Published: August 2018

Resorcinolic lipids, amphiphilic compounds from cereal grains show strong effects upon the activity of membrane enzymes. The concentrations for 50% inhibition of erythrocyte membrane acetylcholinesterase were in the range of 18 -90 μᴍ and were dependent on the length of the aliphatic side chain of the homologue and on the modification of hydroxyl groups in the benzene ring. Sulfonation of OH groups resulted in a drastic decrease of the inhibitory potency. The effect of resorcinolic lipids on the activity of Ca2+(calmodulin)-ATPase was the opposite. Up to concentrations of 50 μᴍ alk(en)ylresorcinols stimulated the activity of this enzyme and only slight inhibition (approx. 30%) was observed above 100 μᴍ. The results suggest that the effect of resorcinolic lipids might depend on their ability to alter the bilayer properties. Most probably these compounds decrease the mobility of membrane phospholipid molecules.