bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Sensitivity of the Ventral Nerve Photoreceptor of Limulus Recovers after Light Adaptation in Two Phases of Dark Adaptation
Authors: Claßen-Linke I. , Stieve H. 
Published: August 2018

The time course of the recovery of the sensitivity of the Limulus ventral nerve photoreceptor was measured during dark adaptation following light adaptation by a bright 1 or 5 s illumination. The stimulus intensity ICR of a 300 μs light flash evoking a response of criterion amplitude (receptor potential or receptor current under voltage clamp conditions) was used as measure of sensitivity.
The time course of dark adaptation shows two phases with time constants in the range of 5-9 s and 300-500 s (15 °C). Only the first of the two phases is significantly changed when the extracel- lular Ca2+-concentration is varied.
The power function ICR = a·Io-tDA
-b gives a good data fit for each of the two phases of dark adaptation. In the first phase the factor ax and the exponent bx are decreased when the external calcium is lowered from 10 mmol/1 to 250 μmol/1. Conversely a1 and b1 are increased when the Ca2+-concentration is raised to 40 mmol/1. For the second phase neither a2 nor b2 is changed significantly upon the changes in calcium concentration in the same experiments.
The two phases of dark adaptation reflect the behaviour of the two components C1 and C2 of the electrical light response (receptor potential or receptor current). Under the conditions described here C, determines the size of the light response during the first phase of dark adaptation whereas C2 mainly influences the size of the response during the second phase.
Interpretation: The fast first phase of dark adaptation is determined by the change in intracellu- lar Ca2+-concentration. The slower second phase of dark adaptation is not primarily calcium- controlled.
A Furanoheliangolide in Helianthus debilis; Implications for a Chemotaxonomy of the Genus Helianthus
Authors: Spring Otmar , Klemt Volker , Albert Klaus , Hager Achim 
Published: August 2018

Abstract
Leaves from Helianthus debilis subsp. cucumerifolius yielded the furanoheliangolide 17,18-dihydrobudlein A . The same compound has been previously isolated from Viguiera hemsleyana, V. procumbens and Helianthus strumosus. 17,18-dihydrobudlein A revealed strong antimicrobial, insecticidal and plant growth inhibiting activity. Its distribution within the plant is restricted to the leaves. Implications for the chemotaxonomy of the genus Helianthus are discussed.
Substrate-Dependent Arylsulfatase Activity in the Cyanobacterium Plectonema 73110
Authors: Müller Sonja , Schmidt Ahlert 
Published: August 2018

Abstract
Plectonem a, Arylsulfatase. Thiosulfate R eductase, Substrate Induction, Cyanobacteria Arylsulfatase activity of the cyanobacterium P lectonem a 73110 is detected during growth on p-nitrophenyl sulfate as only sulfur source. A 60-fold purification of the soluble arylsulfatase yields a protein with an pH-optim um around 10 and K m data for p-nitrophenyl sulfate of 9.5 × 10" 5 and for nitrocatechol sulfate of 3.4 × 10-5. The enzym atic activity is not effected by the cations Mg2-, M n2+, K 2+ or Na + used as chloride salts. The anions SO3
2- and SO4
2-did not inhibit this activity, how ever EDTA , thiols and triton X -100 decreased this activity to about 25% w here­ as SDS inhibited com pletely. Sulfate limitation is necessary for the developm ent of arylsulfatase activity in the presence of its substrate p-nitrophenyl sulfate. This arylsulfatase activity is partly bound to m embranes.
Diethyldithiocarbamate, a New Photosystem I Electron Donor of Mehler-Type Hill Reactions
Authors: Upham Brad L. , Hatzios Kriton K. 
Published: August 2018

Abstract
Diethyldithiocarbamate (DEDTC) does not accept electrons from the photosynthetic electron transport (PET) but can donate electrons to a photosystem I (PSI) Mehler reaction in the pres­ence of the following PET inhibitors: DCMU. DBMIB, and bathophenanthroline. It cannot photoreduce PSI in the presence of cyanide, a PET inhibitor. These data indicate that the site of electron donation is after the plastoquinone pool. Ascorbate is not required for the ability of DEDTC to donate electrons to PSI. There is no photoreductant activity by DEDTC inferredoxin/NADP Hill reactions. Superoxide dismutase inhibits DEDTC/DCMU or bathophenanthroline→methylviologen/O2 Mehler reaction. Catalase does not recover the consumed O2 from a DEDTC/DCMU→methylviologen/O2 Mehler reaction, indicating O2
- has not been dismutating into H2O2. These results indicate that superoxide is required for DEDTC ability to donate electrons, therefore DEDTC is limited only to Mehler-type reactions.
Phenolic Herbicides: Correlation between Lipophilicity and Increased Inhibitory Sensitivity of Thylakoids from Higher Plant Mutants
Authors: Durner Jörg , Thiel Andreas , Böger Peter 
Published: August 2018

Abstract
Pheonlic herbicides, being quite hydrophilic as compared to classical photosystem-II inhibitors do not exhibit a correlation between inhibitory activity and partition coefficient. Sensitivity against phenolic herbicides, however, as observed with atrazine-resistant thylakoids from higher plants mutants (Brassica napus) is increased by higher partition coefficients.
On the Direct Observation of Water-FIuxes in Tissues and Leaves
Authors: Hirth Ulrich-Andreas , Lawaczeck Rüdiger 
Published: August 2018

Abstract
Based on the different absorption spectra of H2O and D2O in the near infrared (NIR, 800-2200 nm) a strategy is developed to measure H2O/D2O-fluxes in thin sections. The physical background of the method is presented. Results on the H2O/D2O-fluxes in filter paper and plant leaves together with both the physical and biological limitations of the new method are discussed.
Induction and Characterization of a NADPH-Dependent Flavone Synthase from Cell Cultures of Soybean
Authors: Kochs Georg , Grisebach Hans 
Published: August 2018

Microsomal preparations from osmotically stressed soybean cells catalyze the conversion of (2S)-naringenin to apigenin in presence of NADPH. In contrast, such preparations from normal soybean cells or from elicitor-challenged cells catalyze the conversion of (2S)-naringenin to genistein (isoflavone synthase). It is concluded that osmotic stress of the cells causes a switch from isoflavone to flavone synthesis. The flavone synthase from osmotically stressed cells corresponds in its properties to the microsomal flavone synthase found in several flowers (G. Stotz and G. Forkmann, Z. Naturforsch. 36c, 737-741 (1981)) and differs from the flavone synthase I from parsley cell cultures which is a soluble Fe2+ and 2-oxoglutarate dependent dioxygenase.
Flavone synthase II from soybean has an absolute requirement for NADPH and oxygen. It is inhibited by carbon monoxide in presence of oxygen and this inhibition is reversed by light. It is also inhibited by cytochrome c and by a number of cytochrome P-450 inhibitors. This and other properties show that flavone synthase II is a cytochrome P-450 dependent monooxygenase.
Fermentation of D-Xylose to Ethanol by Bacillus macerans
Authors: Schepers Hans-Jürgen , Bringer-Meyer Stephanie , Sahm Hermann 
Published: August 2018

Abstract
In the absence of oxygen Bacillus macerans is able to ferment xylose. The principal products are ethanol, formate,CO2, acetone and H2. The yield of ethanol was 61% based on the theoretical value of 0.51 g per g xylose consumed. The cells could grow in the presence of up to 4% (v/v) of added ethanol but the growth rate was already reduced to about 50% by 1% (v/v) of alcohol. Glucose and the pentoses arabinose and xylose were sequentially utilized when initially present as a mixed substrate. Enzymatic studies indicate that xylose was metabolized via the pentosephos-phate and Embden-Meyerhof pathways. At an oxygen concentration of 1-2% air saturation 42 g/l xylose were completely fermented within 160 h and 10 g/l ethanol were produced.
Site Directed Antisera to the D-2 Polypeptide Subunit of Photosystem II
Authors: Geiger R. , Berzborn R. J. , Depka B. , Oettmeier W. , Trebst A. 
Published: August 2018

Three synthetic oligopeptides were used for preparation of antibodies against the D-2 polypeptide of thylakoid membranes. Their sequence was chosen from a model of the folding of the amino acid sequence of the D-2 polypeptide subunit through the membrane that predicted these sequences to be exposed at the membrane surface. For the Merrifield solid-phase method on a fully automated synthesizer the Na-amino group was protected by a fluorenyl-9-methylcarbonyl group. The oligopeptides were coupled to serum albumin by EDAC for immunizations in rabbits.
Antisera with high titer were obtained for the two oligopeptides that contained the amino acid sequence of the D-2 protein from amino acid 230 to 235 and from 235 to 241. The antisera reacted with the D-2 polypeptide, separated on SDS gel and agglutinated the thylakoid membrane.
It is known that certain photosystem II functions are impaired by short time trypsin treatment of the membrane. The antisera were used to show that under these conditions the D-2 polypeptide in the membrane is very sensitive. The trypsination yielded two cleavage products detected by the two antisera, a 20 kDa fragment blotted by antiserum against amino acids 230 to 235 and a 10 kDa fragment blotted by the antiserum against amino acids 235 to 241. As the polypeptide cleavage occurs between the two epitopes, the trypsin cut is therefore at arginine 234. This supports the prediction that the sequence containing this arginine is the most exposed part of the D-2 polypeptide on the membrane (matrix) surface. It is proposed that the high sensitivity of the D-2 polypeptide accounts for the known effect of membrane trypsination on QA accessibility in photosystem II.
Über die ätherischen Öle von Chrysanthemum balsamita L. / On the Essential Oils from Chrysanthemum balsamita
Authors: Strobel Harald , Knobloch Karl , Ziegler Erich 
Published: August 2018

Abstract
The production of essential oil in Chrysanthemum balsamita L. reveals a seasonal dependence. – We conclude that, in blossoms, a dominant influence due to the ontogenetic development of head flowers regulates the production of essential oil. – Freshly harvested head blossoms produced 5 times the amount of oil when compared to fully developed head flowers. Dried leaves contain 5 to 7 times the amount of oil compared to fresh leaves. The composition of the oil from leaves changes more distinctly during the season than the oil from head flowers. Main components of the oil from flowers and leaves are carvon and thujon. During spring and fall, the percentage of sesquiterpenoid hydrocarbons is increased mainly in the oil from leaves. The component β-cubeben can no longer be detected in dried leaves.
Epoxy-trans-isodihydrorhodophytin, ein neuer Metabolit aus Laurencia obtusa / Epoxy-trans-isodihydrorhodophytin, a New Metabolit from Laurencia obtusa
Authors: Imre Sedat , Lotter Hermann , Wagner Hildebert , Thomson Ronald H. 
Published: August 2018

Abstract
Laurencia obtusa, Red Algae, Rhodomelaceae, Acetylenic Ether Epoxy-trans-isodihydrorhodophytin, a new halogenated acetylenic bicyclic ether, has been isolated from a Laurencia obtusa variety, collected in the Marmara sea. Its structure was determined by spectroscopic methods and X-ray diffraction analysis.
Isolation and Characterization of Herbicide Resistant Mutants in the Cyanobacterium Synechococcus R2
Authors: Hirschberg Joseph , Ohad Nir , Pecker Iris , Rahat Ana 
Published: August 2018

A variety of mutants which are resistant to triazine - and urea - classes of herbicides have been isolated in the cyanobacterium Synechococcus R2.
All the mutants that have been analyzed, show some cross-resistance to different herbicides suggesting that these herbicides share a common binding site in photosystem II.
Three psbA genes have been identified in Synechococcus R2. The psbA-copy I gene was cloned from three mutants and used in DNA-mediated genetic transformation. It was found that in all three mutants this gene could transfer the mutation for herbicide resistance indicating that this gene codes for the herbicide resistant protein.
Methylation of Guanine in vivo by the Organophosphorus Insecticide Methamidophos*
Authors: Zayed Salah M . A . D . , Mahdi Fathya M. 
Published: August 2018

Abstract
The methylating capability of methamidophos, assayed by the formation of [7-14C]methylguanine in mouse liver, was investigated using a 14C-insecticide labelled at the O -CH3 group. Following i.p. administration of the toxicant, [7-14C]methylguanine could be isolated from liver nucleic acids of treated mice. The amount of 14C-label reached its maximum 6 h follow ing administration of the insecticide. At maximum 14C-labelling, the amount of 7-methylguanine calculated as fraction of applied dose, was 20-22 × 10-4 and 98 -104 x-4, for DNA and RNA , respectively. The results obtained indicate also, that an appreciable amount of I4C-activity is incorporated via the C-1 pool.
Biotransformation of Humulene by Fungi and Enantioselectivity of the Strains Used
Authors: Abraham Wolf-Rainer , Stumpf Burghard 
Published: August 2018

Abstract
Humulene was transform ed by strains of Chaetomium cochlioides and Diplodia gossypina ATCC 10936 affording 33 new humulanes. The first step is a non-enantioselective epoxidation of the 1,2-double bond, whereas the subsequent hydroxylations were performed preferably at the 1R ,2R -epoxide. To proof these results the anti-1,2;8,9-diepoxide was synthesized and used as substrate. While the 1R ,2R ,8S,9S-antipode of this diepoxide was hydroxylated the other one was recovered unchanged. Diplodia gossypina ATCC 10936 gave the same products but differing in relative and absolute configurations.
PAPS-Reductase from Escherichia coli: Characterization of the Enzyme as Probe for Thioredoxins
Authors: Schwenn Jens D . , Schriek Ulrich 
Published: August 2018

Abstract
PAPS-reductase from Escherichia coli was em ployed to detect thioredoxins from pro- and eukaryotic organisms. A simple method for the isolation of this enzyme and properties of the enzymatic assay were described. A comparison betw een thioredoxins detected by the PAPS-reductase and the Fructose-bisphosphatase or NADP malate dehydrogenase was used to assess the validity of the test. The high cross-reactivity of the bacterial enzyme was useful in the purification of heterologous thioredoxins from spinach, Synechococcus, and Saccharomyces cerevisiae.
A GC/MS Study of the Propolis Phenolic Constituents
Authors: Bankova V. , Dyulgerov Al. , Popov S. , Marekov N. 
Published: August 2018

Abstract
Silylated phenolic fraction from two propolis samples was investigated by capillary GC/MS. Fifteen phenolic acids (seven of them new for propolis), two ketones, new for propolis, eight esters of phenolic acids, new for propolis, six flavanones and two flavonols, were tentatively detected.
Recognition of HLA Class II Molecules by Antipeptide Antibodies Elicited by Synthetic Peptides Selected from Regions of HLA-DP Antigens
Authors: Chersi Alberto , Houghten Richard A. , Morganti Maria C. , Muratti Eleonora 
Published: August 2018

Repeated immunizations of rabbits with chemically synthesized peptides from selected regions of HLA-DP histocompatibility antigens resulted in the production of specific antibodies that were then isolated from the immune sera by chromatography on Sepharose-peptide immunoadsorbents.
The purified antibodies, when tested with an enzyme-linked immunosorbant assay, specifically bound to the inciting fragments; moreover, two of them recognized glycoproteins extracted by nonionic detergents from human chronic lymphocytic leukemia cells, as revealed by binding assays.
The results suggest that amino acid stretches 51 - 61 of the alpha chain and 80-90 of the beta chain of HLA-DP histocompatibility antigens are likely exposed on the surface of the protein molecule.
The specific recognition of DP regions is strongly suggested by the difference in the binding of those antibodies to soluble membrane proteins, as compared to the binding of monomorphic anti-Class II monoclonal antibodies to the same antigens.
A Novel Caffeic Acid Derivative and Other Constituents of Populus Bud Excretion and Propolis (Bee-Glue)
Authors: Wollenweber Eckhard , Asakawa Yoshinori , Schillo Detlef , Lehmann Ulrich , Weigel Heidrun 
Published: August 2018

Abstract
The bud exudates of Populus nigra, P. trichocarpa, and P. grandidentata × tremuloides were analyzed for the presence of phenolics and flavonoids. A novel natural product, caffeic acid y.y-dimethylallyl ester, was identified from P. nigra, along with further phenolics such as ρ-hydroxy-acetophenone, dimethyl caffeic acid, cinnamoyl cinnamata and vanillin. The flavonoid aglycones correspond to those reported earlier. Propolis samples from the Sonoran Desert were shown to exhibit the flavonoid pattern that is typical for poplar bud exudates, thus confirming this material as the major source for bee-glue. Only a single flavonoid might originate from the leaf exudate of a desert shrub.
Polyunsaturated Pheromones: Semi-Synthesis of-(Z,Z)-6,9-Alkatrienes and (Z,Z,Z)-3,6,9-Alkatrienes from Naturally Occurring Fatty Acids
Authors: Mangold H. K. , Becker H . , Schulte E. 
Published: August 2018

Abstract
Chain elongation of the methyl esters of linoleic and linolenic acids by one, two, or three methylene groups followed by elimination of the functional groups leads to (Z,Z)-6,9-alkadienes and (Z,Z,Z)-3,6,9-alkatrienes that function as pheromones in various insects. All of the simple reactions involved proceed in excellent yield, they do not require expensive reagents, high pressure or high temperature. The route of synthesis is applicable on a large scale. Rigorous analyses prove the purity of the hydrocarbons prepared.
Dimers of Altersolanol A from Alternaria solani
Authors: Lazarovits George , William R. , Stoessl Albert 
Published: August 2018

Abstract
Weakly phytotoxic, water-soluble pigments from culture filtrates of the potato early blight organism Alternaria solani have been identified by 1H NMR, UV, mass spectrometric, and acetylation studies as the pair of rotamers represented by structure 1a.
Chemical Analysis of Peptidoglycans from Species of Chromatiaceae and Ectothiorhodospiraceae
Authors: Meißner Joachim , Jürgens Uwe J. , Weckesser Jürgen 
Published: August 2018

Abstract
Rigid layer (sodium dodecylsulfate(SDS)-insoluble cell wall) and peptidoglycan fractions were obtained from the Chromatiaceae (Thiocysüs violacea and Chromatium tepidum) and from Ectothiorhodospira vacuolata. Chemical composition of rigid layers from all three species indicated the presence of peptidoglycan-bound protein.
Qualitative and quantitative composition of isolated peptidoglycan indicate an Aly-type. meso-Diaminopimelic acid was the only diamino acid found. Direct cross-linkage of peptide sidechains was confirmed by separation of respective dipeptides (M-A;pm-D-Ala) from partial acid hydrolysates of peptidoglycan. GlcN and MurN of the sugar strands are completely N-acetylated. All peptidoglycan fractions contained small amounts of Gly.
Enzymatic Studies on the Reversible Synthesis of Nicotinic Acid-N-glucoside in Heterotrophic Parsley Cell Suspension Cultures
Authors: Upmeier Barbara , Thomzik Jürgen E. , Barz Wolfgang 
Published: August 2018

Abstract
A soluble enzyme catalyzing the transfer of the glucose moiety from UDP-glucose to the nitrogen atom of nicotinic acid was detected in protein preparations from heterotrophic cell suspension cultures of parsley (Petroselinum hortense Hoffm.). Enzyme activity was enriched 22-fold by ammonium sulfate precipitation, gel filtration and ion exchange chromatography. The UDP-glucose : nicotinic acid-N-glucosyltransferase showed a pH-optimum at pH 7.8-8.2 and a temperature optimum at 30 °C. The apparent KM values were determined to be 170 μM for nicotinic acid and 1.2 mM for the cosubstrate. The native enzyme had a molecular mass of about 46 kDa. The glucosyltransferase reaction was shown to be reversible. The transfer of the glucose molecule from nicotinic acid-N-glucoside to uridinediphosphate yielding uridinediphosphoglucose and nicotinic acid could be demonstrated indicating that nicotinic acid-N-glucoside has a high group-transfer potential.
Do Monoclonal Antibodies Recognize Linear Sequential Determinants?
Authors: Camera Matildé , Muratti Eleonora , Trinca Maria Luisa , Chersi Alberto , Elena Regina 
Published: August 2018

Abstract
A group of 19 anti-class II monoclonal antibodies produced in different laboratories were tested in ELISA for their ability to bind to a panel of synthetic peptides selected from HLA-DQ alpha and beta chains. No one of the antibodies tested was found to react with the synthetic fragments, thus confirming the common finding that MoAbs generally fail to recognize fragments of the native antigen. The possibility that this result might be partly due to the procedure used for screening hybridoma supernatants is discussed.
A Competitive Inhibition Enzyme Immunoassay for Detection and Quantification of Organophosphorus Compounds
Authors: Schmidt Peter , Kühlmann Reiner , Lösch Uli 
Published: August 2018

A sensitive and specific method for detection and quantification of methyl phosphonic acid, paminophenyl 1,2,2,-trimethyl-propyl diester (MATP) as a model substance for organophosphorus compounds is described.
Different procedures for coupling the haptenic group for immunization, purification and immobilization allowed the detection of hapten-specific antibodies.
The competitive inhibition enzyme immunoassay (CIEIA), using purified chicken and rabbit IgG-antibodies, was able to detect MATP-concentrations as low as 10-10 mol/1.
Based upon our results, we postulate that the CIEIA represents a good alternative to the customary diagnosis of organophosphate intoxications, measuring blood Cholinesterase activity.
Solution Conformations of Some Acyclo Nucleoside and Nucleotide Analogues of Antiviral Acyclonucleosides, and Their Substrate/Inhibitor Properties in Several Enzyme Systems
Authors: Stolarski Ryszard , Lassota Piotr , Kazimierczuk Zygmunt , Shugar David 
Published: August 2018

Chemical and enzymatic procedures have been employed for the preparation of various phosphorylated derivatives of the acyclonucleoside 9-(1,3-dihydroxy-2-propoxymethyl)adenine, an analogue of the active antiviral agent 9-(1,3-dihydroxy-2-propoxymethyl)guanine (DHPG). In combination with the previously reported 2′,3′-seco nucleosides and their phosphates and cyclic phosphates (Stolarski et al., Z. Naturforsch. 41c, 758-770, 1986), this made available a broad class of acyclonucleosides and nucleotides, the acyclic moieties of which are capable of mimicing the ribose and 2′-deoxyribose rings.
The solution conformations of the foregoing were determined with the aid of 1H, 13C and 31P NMR, and compared with those of DHPG and 9-(hydroxyethoxymethyl)guanine (Acyclovir, ACV). Particular attention was devoted to conformations about C-O bonds in different acyclic fragments, which demonstrated well-defined differences between 2′,3′-seco derivatives on the one hand (conformational “rigidity”) and derivatives with DHP and AC acyclic chains on the other (rotation about the C(1′)-O(4′) bond). The overall results are in good general agreement with reported crystal structures, and are compared with those obtained by quantum mechanical calculations.
The conformational features of the various compounds are also discussed in relation to their substrate and/or inhibitor properties in a number of enzyme systems, including adenosine deaminase, phosphodiesterases, nuclease P1, 3′-nucleotidase and herpes virus type 1 thymidine kinase.