bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of the Light-Induced Oxygen Gas Exchange from the IC 2 Deletion Mutant of Synechocystis PCC 6803 Lacking the Photosystem II 33 kDa Extrinsic Protein
Authors: Boichenko V. A. , Klimov V. V. , Mayes S. R. , Barber J. 
Published: August 2018

Abstract
The absence of the extrinsic Mn-stabilizing 33 kDa protein in the IC 2 mutant of Synechocystis PCC 6803 disturbs the redox cycling of the water splitting system and retards the formation of its higher S-states (I. Vass, K. Cook, S. Deak, S. R. Mayes, and J. Barber, Biochim. Biophys. Acta 1102, 195-201 (1992)). We have performed analyses of the flashinduced oxygen exchange in the mutated cyanobacterium to clarify further the role of the 33 kDa protein. Under aerobic conditions, both the wild type and IC2 mutant show a relatively slow signal of oxygen rise on the first flash which is increased about twice by the addition of 10 μᴍ DCMU and significantly diminished by lowering the oxygen concentration in the medium. According to action spectra measurements, this mode of apparent oxygen release is mediated by PS I and can be attributed to a light induced inhibition of respiratory activity. In contrast to the wild type, having the usual oxygen evolution flash pattern with a periodicity of four, the IC2 mutant shows a binary oscillation pattern of flash-induced respiratory oxygen exchange at a flash frequency 10 Hz, being dampened with DCMU or by a lower flash frequency (< 1 Hz). Oxygen evolution due to water splitting is clearly seen in the IC2 mutant when background far-red illumination is applied to saturate the signal due to respiratory inhibition, but a quadruple oscillatory component of flash-induced oxygen evolution appears only in the presence of artificial electron acceptors under partial aerobic conditions. The mutant possesses a higher PS I/PS II ratio compared to the wild type, as judged from both the flashinduced yields and quantum efficiencies of the steady-state rates of the oxygen exchange reactions. Estimates of antenna sizes indicate about a 20% decrease of optical cross-section at 675 nm of the PS II unit in IC2 mutants in comparison with the wild type. It is suggested that the absence of the 33 kDa protein leads to a modification of the PS II assembly and because of the slowing down of the S-state cycle, the rate of cyclic electron flow around PS II is enhanced. It seems that the absence of the 33 kDa protein in Synechocystis 6803 also disturbs energy transfer between adjacent PS II core complexes and may also alter their association with the phycobilisomes.
Molecular Mobility of Sucrose in Aqueous Solution Studied by 13C NMR Relaxation
Authors: Girlich D. , Lüdemann H.-D 
Published: August 2018

Abstract
From the temperature and concentration dependence of the 13C spin lattice relaxation times of the 12 carbon atoms of the sucrose molecule the rotational dynamics of the sugar molecules are determined. No indication for conformational mobility of the rings is found. The exocyclic hydroxymethyl groups possess extra mobility. The models used for the description are critically discussed. The temperature dependence of the rotational mobility is described by a VTF equation. The concentration dependence of the ideal glass transition temperature To for this mobility is derived.
Uptake and Transport of Quinolizidine Alkaloids in Cuscuta reflex a Parasitizing on Lupinus angustifolius
Authors: Bäumel P. , Jeschke W. D. , Witte L. , Czygan F.-C. , Proksch P. 
Published: August 2018

Abstract
Cuscuta reflexa, Lupinus angustifolius, Quinolizidine Alkaloids, Parasitism During parasitism on Lupinus angustifolius the phanerogamic parasite Cuscuta reflexa takes up quinolizidine alkaloids from L. angustifolius via haustoria that tap xylem and phloem ves­sels of the host. The alkaloid pattern of the haustorial region of C. reflexa as revealed by GLC as well as by GLC-M S closely resembles that of infested lupin stems. With increasing distance from the haustoria towards the apex of C. reflexa the complex alkaloid pattern of the host is significantly reduced. Whereas alkaloid esters such as 13-benzoyloxylupanine and 13-cinnamoyloxy-lupanine are prominent peaks in the alkaloid profiles of the host as well as of the haustorial region of the parasite they are not detected in the apex of C. reflexa but are replaced by their respective alcohol com ponent 13-hydroxylupanine. This change of alkaloid profiles is accompanied by a strong decline of alkaloid concentration which drops from ap­ proximately 11 m g/g dry wt. in the haustorial region of C. reflexa to 0.2 m g/g dry wt. in the apex. Alkaloid analyses of xylem sap and phloem exudate from L. angustifolius suggest that uptake of host plant alkaloids by C. reflexa is mainly via the phloem even though a contribu­tion of xylem sap to the supply of alkaloids to the parasite can not be excluded.
Partial Purification and Characterization of Membrane-Associated 3-Hydroxy-3-methylglutaryl-Coenzyme A Lyase from Radish Seedlings
Authors: Weber Thomas , Bach Thomas J. 
Published: August 2018

Abstract
We solubilized from radish membranes and purified by 154-fold 3-hydroxy-3-methyl-glutaryl-CoA lyase (HMGL, EC 4.1.3.4) catalyzing the conversion of 3-hydroxy-3-methyl-glutaryl-(HMG -)CoA into acetyl-CoA and acetoacetate. The apparent molecular mass under non-denaturating conditions is 70 kDa. The enzyme has a broad pH optimum around 8.0 and its activation energy as determined from the linear part of an Arrhenius plot is 137.1 kJ/mol. The Km with respect to (5)-H MG-CoA is 40 μM . The enzyme is extremely unstable and rapidly loses activity even when kept on ice, but retains some activity over several weeks when stored at -80 °C.
Synthesis of Protoheme via Both, the C5-and the Shemin-Pathway, in the Pigment Mutant C-2 A′ of Scenedesmus obliquus
Authors: Drechsler-Thielmann Beate , Dörnemann Dieter , Senger Horst 
Published: August 2018

During greening of pigment mutant C-2A′ of Scenedesmus obliquus the iron tetrapyrrole protoheme is synthesized via 5-aminolevulinic acid (ALA). In this organism ALA can be formed either via the C5- or the Shemin-pathw ay. [14C]labeling with precursors of both pathways led to radioactive protoheme. [1-14C]glutamate, the substrate of the C5-pathway, labeled protoheme 7 times more efficiently than [2-14C ]glycine, a substrate most effective for the Shemin-pathway. Labeling experiments in the presence of different inhibitors were carried out to prove the specificity of the observed labeling. Gabaculine, a highly effective inhibitor of glutamate-1-semialdehyde aminotransferase, one of the enzymes of the C5-pathway, led to a decrease in [1-14C ]glutamate incorporation, and to an increase in [2-14C]glycine label, showing that the pathways work independently from each other. With DCMU only the incorporation of [1-14C ]glutamate was reduced, indicating that the C5-pathway activity is depending on plastidic energy supply.
The presented data confirm the existence of both pathways to 5-aminolevulinic acid in the pigment mutant C-2A′ of Scenedesmus and their involvement in protoheme formation. It is concluded that the C5-pathway provides the bulk of protoheme for the plastidic electron transport chain and the Shemin-pathway for the minor part of the hemes needed for the electron transport in the mitochondria.
Factors Controlling Medium-Chain Fatty Acid Synthesis in Plastids from Maturing Cuphea Embryos
Authors: Fuhrmann Jochen , Heise Klaus-Peter 
Published: August 2018

Abstract
The colorless embryos of Cuphea wrightii A. Gray accumulate capric (about 30%) and lauric acid (about 50%) in their storage lipids. Fractionation studies show that the capacities for the synthesis of these medium-chain fatty acids (MCFA) from [1-14C]acetate were strictly bound to intact plastids. These, in turn, obligately required the addition of ATP. ATP could partially be substituted by ADP. Reduction of the pyridine nucleotide pool, required for opti­mum MCFA formation within the plastids, was driven by glucose 6-phosphate. Under these conditions the plastids were capable of synthesizing MCFA like the intact tissue. The presence of CoA in the incubation medium induced acyl-CoA formation.
The observed accumulation of unesterified capric and lauric acid in the absence of CoA suggests that acyl-ACP thioesterase activity is involved in the chain termination. Treatment with cerulenin led to an unexpectedly small reduction of total fatty acid synthesis while the chain elongation of capric acid was clearly inhibited. A similar accumulation of capric acid at the expense of longer chain fatty acids has been observed after replacing ATP by ADP. These findings implicate that even the condensing enzymes are involved in the control of chain ter­mination.
Metabolie Reduction of Phenylpropanoid Compounds in Primary Leaves of Rye (Secale cereale L.) Leads to Increased UV-B Sensitivity of Photosynthesis
Authors: Reuber S. , Leitsch J. , Krause G. H. , Weissenböck G. 
Published: August 2018

Abstract
In the epidermal layers of rye primary leaves two flavone glycosides and several hydroxycinnamoyl esters are localized, whereas the mesophyll contains two flavone glucuronides and two anthocyanins. The concentrations of all these potential UV-B protective phenylpropanoid compounds could be reduced by application of 2-aminoindan-2-phosphonic acid (AIP), an efficient inhibitor of phenylalanine ammonia-lyase (EC 4.1.3.5). Photosystem II in the primary leaves of seven-days-old plants, grown in the presence of 20 μm AIP up to an age of 80 h, was more severely affected by UV-B than in control plants with the normal concentration of phenylpropanoid compounds. Damage of photosystem II in vivo was estimated by measuring the chlorophyll a fluorescence (parameter FJFm) of PS II. The results indicate an essential role of phenylpropanoid com pounds as UV-B protectants in rye primary leaves
Oxidative Stress of Crops Monitored by EPR
Authors: Stegmann Hartmut B. , Schuler Paul 
Published: August 2018

Abstract
Treatment of leaves of spinach, corn, and peas with the herbicides paraquat, amitrole or acifluorfen leads to oxidative stress resulting in a light driven drastically increased production of ascorbic acid radical (m̱onoḏehydroa̱scorbic acid, MDAA) which could be demonstrated by in vivo EPR analysis. A discrimination of the MDAA formation between the action of elec­tron uncouplers and catalase inhibitors can be achieved by observation of the radical rise kinetics. Significant MDAA signal intensities are detected in the darkness likewise. These signals are probably due to the action of ascorbic acid oxidase activated by membrane destruction.
4-Epidihydrocochlioquinone B and 14-Epicochlioqumone B, Antibiotics from Fermentations of the Ascomycete Neobulgaria pura: Structure Elucidation and Effects on Platelet Aggregation
Authors: Lorenzen Kirsten , Anke Timm , Anders Uwe , Hindermayr Hermann , Hansske Fritz 
Published: August 2018

Abstract
14-Epicochlioquinone B (1) and 14-epidihydrocochlioquinone B (2) were isolated from sub­ merged cultures of Neobulgaria pura (Pers. ex Fr.) Petrak. 14-Epicochlioquinone B is a potent inhibitor of hum an and bovine platelet aggregation stimulated by different inducers. 14-Epidihydrocochlioquinone B does not inhibit the aggregation of platelets. In addition, both 1 and 2 exhibited cytotoxic and antimicrobial activites.
Phylogeny and Biotransformation. Part 5*: Biotransformation of Isopinocampheol
Authors: Abraham Wolf-Rainer 
Published: August 2018

Abstract
Biotransformation of isopinocampheol with 100 bacterial and fungal strains yielded 1-, 2-, 4-, 5-, 7-, 8 - and 9-hydroxy-isopinocampheol besides three rearranged monoterpenes, one of them bearing the novel isocarane skeleton. A pronounced enantioselectivity between (+)- and (-)-isopinocampheol was observed. The phylogenetic position of the individual strains could be seen in their ability to form the products from (+)-isopinocampheol. The formation of 1,3-dihydroxypinane is a domain of bacteria, while 3,5- or 3,7-dihydroxypinane was mainly formed by fungi, especially those of the phylum Zygomycotina. The activity of Basidiomycotina towards oxidation of isopinocampheol was rather low. Such informations can be used in a more effective selection of strains for screening.
Spermatozoid Chemotaxis in Laminaria digitata (Phaeophyceae). III. Pheromone Receptor Specificity and Threshold Concentrations
Authors: Maier Ingo , Müller Dieter G. , Boland Wilhelm 
Published: August 2018

Abstract
The pheromone receptor specificity and threshold concentrations have been determined for spermatozoid chemotaxis in Laminaria digitata in structure-activity studies. The results are in agreement with the current concept on the pheromone receptor interaction in brown algae, which is based on mutually-induced dipole-dipole interaction, dispersion forces and hydrophobic forces. Comparison with the receptor specificity in pheromone-induced spermatozoid release in the same species indicates that different pheromone receptors are involved in these two functions.
Composition of the Epicuticular Wax Esters of Picea abies (L.) Karst
Authors: Sümmchen Peter , Markstädter Claus , Wienhaus Otto 
Published: August 2018

Abstract
The long-chain alkyl esters homologues of the cuticular needle wax of Picea abies consist of a series of isomers, which are formed by different n-fatty acids and n-alkanols of various chain lengths. Even-numbered esters are dominating. Methyl esters range from C27 to C37, even-numbered esters are only minor components. Furthermore, a new class of homologue wax esters was isolated. Examination by gas chromatography, mass spectroscopy and chemi­cal studies resulted in identification of pentenyl esters of triacontanoic, dotriacontanoic, tetratriacontanoic and hexatriacontanoic acid.
Changes in the Content of Chlorophyll and Redox Components of the Thylakoid Membrane during Development and Senescence of Beech (Fagus sylvatica) Leaves
Authors: Zhu Hua , Wild Aloysius 
Published: August 2018

Abstract
Leaves from 145-year-old and 44-year-old beech trees were harvested during 1991-1993. Chlorophyll (Chl) and redox components of the thylakoid membrane, including P-700, cytochrome f (Cyt f) and D1 protein, were determined with the following results. Chl a + b, P-700 and Cyt f per unit of fresh weight (FW), dry weight (DW) and leaf area (LA) increase significantly during leaf development. This can be attributed to a massive membrane syn­thesis and new thylakoid formation in the cells. The Chl a/Chl b ratio decreases with the synthesis of Chl during the development of beech leaves and is reduced further with Chl breakdown in the stage of senescence. When expressed on the basis of Chl, a reduction in the amount of P-700 and Cyt f is observed during the growth stage, indicating a marked enlargement of the functional photosynthetic unit. During senescence of beech leaves, Chl breaks down, and P-700 and Cyt f per unit of FW, DW and LA decrease dramatically with the decline in Chl levels. However, when expressed on the basis of Chl, P-700 remains rela­tively constant, while Cyt f shows a pronounced increase. The uncommon pattern of Cyt f change in senescent beech leaves and the relationship between the amount of Chi and the content of Cyt f throughout an entire growth period of beech leaves are discussed.
A New Clerodane Diterpenoid Isolated from Propolis
Authors: Matsuno Tetsuya 
Published: August 2018

Abstract
A physiologically active substance has been isolated from Brazilian propolis and charac­terized as a new clerodane diterpenoid, as indicated by human hepatocellular carcinoma HuH 13 cell cytotoxicity assays. This compound inhibited growth of the hepatoma cells at a concentration around 10 μg/ml and arrested the tumor cells at S phase as revealed by flow cytometry. At higher concentrations it exerted lethal damage. The compound showed cyto­toxicity on human lung carcinoma HLC-2, HeLa, KB and rat W3Y cells, whereas human diploid foreskin and primary rabbit kidney cells were less affected.
Purification and Partial Characterization of the Streptomyces viridochromogenes TÜ494 Phosphinothricin-N-acetyltransferase Mediating Resistance to the Herbicide Phosphinothricin in Transgenic Plants
Authors: Vinnemeier Josef , Dröge-Laser Wolfgang , Pistorius Elfriede K , Broer Inge 
Published: August 2018

Abstract
A purification scheme for the enzyme phosphinothricin-N-acetyltransferase (PAT) originating from Streptomyces viridochromogenes {pat-gene product from Streptomyces virido­chromogenes) and mediating herbicide resistance to transgenic plants was developed. The enzyme was isolated from a transformed and overproducing Escherichia coli strain. With a combination of ammonium sulfate fractionation, chromatography on DEAE-Sephadex A50-, Phenylsepharose-, Hydroxylapatite-and FPLC-Superose 12-columns it was possible to obtain PAT which was at least 90 % homogeneous on the basis of SDS-PAGE. The properties of the isolated PAT were compared with the properties of PAT from S. hygroscopicus (bar-gene product from S. hygroscopicus) previously isolated and characterisized by Botterman, J., Gossele, V., Thoen, C., Lauwereys, M. (1991), Gene 102, 33-37. Differences were observed in the molecular masses of the two native enzymes (PAT from S. viridochrogenes being a dimer of 40 kD and PAT from S. hygroscopicus being a monomer of 21 kD), and in the temperature sensitivity of the two enzymes (the PAT from S. viridochromogenes being slightly more temperature stable than PAT from S. hygroscopicus). However, since the pat and the bar-gene are to 85 % homologous, substantial similarities exist between the two enzymes especially in the kinetic values and the substrate specificity. The isolated S. virido­chromogenes PAT did not acetylate putative substrates present in the plant cell. Antibodies were raised against the isolated protein. This antiserum was able to detect PAT in transgenic plants and therefore is suitable to analyse the fate of the protein in such plants under various stress conditions.
Fungal Melanin Biosynthesis Inhibitors: Introduction of a Test System Based on the Production of Dihydroxynaphthalene (DHN) Melanin in Agar Cultures
Authors: Thines Eckhard , Daußmann Thomas , Sterner Olov , Semar Martin , Anke Heidrun 
Published: August 2018

In a screening for inhibitors of fungal melanin biosynthesis a novel test system was success­ fully employed. With this test system, based on the production of dihydroxynaphthalene melanin (DHN melanin) by a Lachnellula species in agar cultures, extracts of cultures of basidiomycetes, ascomycetes and deuteromycetes were tested. From fermentations of Col-lybia dryophila, 6-methylpurine (1) and 6-methyl-9-β-ᴅ-ribofuranosylpurine (2) were isolated as the active principles and 3,5-dichloro-4-methoxybenzoic acid (3) was obtained from cultures of Stropharia squamosa. The corresponding alcohol (4) and aldehyde (5) previously isolated from several basidiomycetes, were also active in this test system. In a screening of fungal metabolites, 1-methoxy-8-hydroxynaphthalene and 1,8-dimethoxynaphthalene inhibited biosynthesis of DHN melanin.
Among the inhibitors identified, compounds 3 -5 were the most selective ones. They were the only metabolites without cytotoxic activities.
Glycerol Inhibits or Uncouples the Plasma Membrane (Ca2++Mg2+)ATPase of Kidney Proximal Tubules Depending on the Ca2+ Concentration
Authors: Sola-Penna Mauro , dos Passos Lemos Adriana , Vieyra Adalberto 
Published: August 2018

In this report it is shown that glycerol (0.5-10% v/v) stimulate the C12-E9-solubilized renal (Ca2++Mg2+)ATPase in the presence of low concentrations of free Ca2+ (< 10-6ᴍ). At 4% (v/v), the polyol decreases the K0.5 for Ca2+ from 1.15 to 0.22 μᴍ
at the high-affinity site, and a very-high-affinity Ca2+ component appears. This component has a K0.5 ≤10-9 ᴍ and its maximal velocity is about one-third that of the fully activated enzyme (at 10-20 μᴍ Ca2+), which is not affected by glycerol (21.1 and 20.2 nmol·mg-1 ·min-1 in the absence and presence of the polyol, respectively). The low-affinity, inhibitory component of the Ca2+ curve (50-1000 μᴍ ) is also unaffected by glycerol. With 0.07 μᴍ free Ca2+ and soluble enzyme, the stimulatory effect of glycerol saturates at ≈10% (v/v). In contrast, with 17 μᴍ free Ca2+, glycerol has little effect up to 10% (v/v), and then progressively inhibits ATPase activity. These data indicate that the effect of the polyol is modulated by the occupancy of the high-affinity Ca2+ sites. In native vesicles, the stimulation promoted by low concentrations of glycerol at low concentrations of Ca2+ is accompanied by inhibition of active Ca2+ transport, indicating that, in these conditions, the polyol uncouples ATPase activity and ATP-driven Ca2+ influx.
Collybial, a New Antibiotic Sesquiterpenoid from Collybia confluens (Basidiomycetes)
Authors: Simon Brigitte , Anke Timm , Andersb U. , Neuhausb M. , Hansske F. 
Published: August 2018

Abstract
A new antibiotic was isolated from fermentations of an american strain of Collybia confluens. Its structure was elucidated by spectroscopic methods as 2,10,10-trimethal-4-oxo-tricyclo[7.2.0.02.5]undec-6-en-carbaldehyde (with the relative stereo chemistry IS, 2R, 5R, 9R) (1). The inhibitor, which was named collybial, is structurally related to koraiol, a sesquiterpenoid isolated from Pinus koraiensis (Khan V. A. (1979), Khim. Prir. Soedin 5, 652-658).
Collybial inhibited the growth of Gram-positive bacteria at concentrations starting from 21.5 μm . The propagation of vesicular stomatitis virus (VSV) in baby hamster kidney (BHK-21) cells was inhibited by 21.5 μm collybial. Cytotoxic effects on BHK cells were observed at 5 fold higher concentrations.
Effects of Pharmacological Agents on Ecdysteroid Synthesis in vitro in Ovaries and Abdominal Integument from Female Adult Crickets, Gryllus bimaculatus de Geer (Ensifera, Gryllidae)
Authors: Lorenz Judith , Lenz Margit , Hoffmann Klaus H. 
Published: August 2018

Abstract
In female adults of Gryllus bimaculatus, ovaries as well as the abdominal integument produce free and conjugated ecdysteroids in vitro (Hoffmann et al., 1992). The aim of the current study was to determine the influence of various potential ecdysteroid biosynthesis effectors (RH 5849, KK 42, diflubenzuron, ketoconazole, azadirachtin, acetylenic and allenic cholesteryl derivatives B1, B6, AL2), and also of the protein synthesis inhibitor cycloheximide, on net release of moulting hormones in vitro by the adult ecdysteroid sources. All the compounds examined can be divided into four groups due to their different effectiveness on both the ecdysiosynthetic tissues. The non-steroidal ecdysteroid agonist RH 5849 (group 1) enhanced ecdysteroid synthesis in ovaries, but inhibited hormone production in the abdominal integument. Treatment in vitro with diflubenzuron (dimilin) and cycloheximide (group 2) strongly reduced ovarian ecdysteroid synthesis whereas they were hardly effective on integumental hormone production. The group 3 compounds (ketoconazole, B1, B6, AL2, azadirachtin A) demonstrated a stronger inhibitory effect on the abdominal integument than on the ovary. The imidazole compound KK 42 (group 4) was a very potent effector of ecdysteroid biosynthesis in both hormone sources.
The Biflavonoid Pattern of the Moss Bartramia ithyphylla (Bartramiaceae, Musci)
Authors: López-Sáez José Antonio , Pérez-Alonso María José , Velasco-Negueruela Arturo 
Published: August 2018

Abstract
From Bartramia ithyphylla the following five biflavonoids were isolated: philonotisflavone, 2,3-dihydrophilonotisflavone, dicranolomin, 5′,3′′′-dihydroxyamentoflavone and 5′-hydroxyamentoflavone.