bluuebunny/crossref_metadata_2025_split huggingface dataset:
Latitude Dependent Circadian Rhythms of Carabid Beetles
Authors: Leyk Gisela , Martin Wolfgang 
Published: August 2018

Abstract
Comparative studies of circadian activity rhythms were performed with three stocks of the species Pterostichus rhaeticus Heer (from Southern Europe, Central Europe, and the Subarctic) and with one Central European stock of the sibling species Pterostichus nigrita Paykull. The hehaviour was investigated in various LD conditions, constant conditions including LL with changes of the illumination intensity and constant darkness with light pulses. The data were analysed with the program system “Timesdia” containing various techniques like power spectrum estimation, periodogram analysis and complex demodulation. This allowed to reveal the time course of rhythms and to determine the number of phase jumps as a measure for precision. With the help of these methods, the activity patterns are classified in different types of behaviour: synchronization, temporarily synchronization, aperiodic behaviour, free run, temporarily free run, relative entrainment, and relative coordination. Besides graduated differences between the populations in south-to-north direction (e.g. in the tendency to rhythmic behaviour) the analysis revealed splitting of rhythms into two or even three components of different frequencies and transitions from rhythmic to aperiodic behaviour or vice versa after arbitrarily chosen light pulses in constant darkness. This behaviour cannot be explained by a system which is composed of one single limit cycle oscillator, but the results rather support a multi-oscillator model.
A Simple Analysis of Purine and Pyrimidine Nucleotides in Plant Cells by High-Performance Liquid Chromatography
Authors: Ashihara Hiroshi , Mitsui Kaori , Ukaji Toshiko 
Published: August 2018

Abstract
Purine and pyrimidine nucleotides, extracted from cultured plant cells with 6 % perchloric acid, were separated directly with HPLC using anion-exchange Shimpack WAX -1 column. More than fifteen nucleoside mono-, di-, and triphosphates and nucleotide sugars were clearly separated and quantified without any interference from plant phenolic compounds.
A Vitamin D3 Steroid Hormone in the Calcinogenic Grass Trisetum flavescens
Authors: Rambeck W. A. , Weiser H. , Zucker H. 
Published: August 2018

Abstract
The grass Trisetum flavescens (golden oat grass, Goldhafer) causes soft tissue calcification in cattle and in sheep. The calcinogenic principle of the plant is the active vitamin D steroid hormone 1,25-Dihydroxyvitamin D3, the major physiological regulator of calcium homeostasis in higher animals. From comparison with synthetic vitamin D metabolites in different bioassays, it is concluded that T. flavescens contains the 25-glucoside of 1,25(OH)2D3. This compound, or rather the 1,25(OH)2D3 liberated by ruminal fluid, is the calcinogenic factor of the grass.
In vivo Screening of Glutathione Related Detoxification Products in the Early State of Drug Development
Authors: Prox A. , Schmid J. , Nickl J. , Engelhardt G. 
Published: August 2018

Abstract
Glutathione (GSH) adducts and consecutive degradation products thereof are indications of reactive intermediates during drug metabolism. As demonstrated with the analgesic SX-PP 16 (4-amino-3,5-dibromacetanilide), however, interactions of a drug with GSH can be detected by labelling the GSH-stores with labelled cysteine, and consecutive administration of the unlabelled drug even at therapeutic doses. The GSH-adducts are sensitively and specifically traced by HPLC, applying column-switching and a combination of diode array-and radioactivity detection. This approach seems to be much more sensitive than a classical GSH-depletion study. The structure of the main metabolite of SX-PP 16 (46% of urinary excretion) was elucidated as 3-bromo-4-amino-5-mercapturyl-acetanilid.
The 14β-Hydroxylation in the Biosynthesis of Cardenolides in Digitalis purpurea. The Role of 3β-Hydroxy-5β-pregn-8(14)-en-20-one
Authors: Deluca Mónica E. , Seldes Alicia M. , Gros Eduardo G. 
Published: August 2018

Abstract
Labelled 3β-hydroxy-5β-pregnan-20-one was incorporated by Digitalis purpurea plants into digitoxin while 3β-hydroxy-5β-pregn-8(14)-en-20-one was not. This result excluded the intermediary role of the latter compound as precursor of cardenolides in the mentioned plant.
A New Method of Solvation Analysis: Applications to Quinones
Authors: Keske Jonathan M. , Bruce J. Malcolm , Dutton P. Leslie 
Published: August 2018

Abstract
A new method of analysis of the factor contributing to solvation of small molecules is described. Approximations of the energetic contributions to the entry of a molecule into water have been derived from partition coefficient data of solutes and selected derivatives from a multiplicity of solvents. These include taking separate account energy of the cost of introduction of a molecular cavity in water, the strength of solute-water dipolar interactions, and the strengths of hydrogen bond formation with water of the lone pairs and hydroxylic hydrogens associated with the molecule. In this report the solvation-free energies of benzoquinone and hydroquinone in water are described. We also consider the solvation of the sem iquinone anion and show it to be fundamentally different from that of either the quinone or hydroquinone; this is discussed as a potentiality for selective binding (“solvation”) of quinone, sem iquinone and hydroquinone in sites of redox catalysis such as those found in the photosynthetic reaction center.
Re-Activation of the Expression of Glyoxysomal Genes in Green Plant Tissue
Authors: Birkhan Ralf , Kindl Helmut 
Published: August 2018

Abstract
Biochemie, Fachbereich Chemie, Universität Marburg, Hans-Meerwein-Straße, D-3550 Marburg, Bundesrepublik Deutschland Z. Naturforsch. 45c, Isocitrate Lyase c DNA, Malate Synthase c DNA, Glyoxysome, Leaf Peroxisome, Transition of Organelles Glyoxysomes are being replaced by leaf-type peroxisom es during the greening of dark-grown cucumber cotyledons. Light functions in this process as negative modulator of the gene expression of glyoxylate cycle enzymes but as positive regulator for the activation of glycollate oxidase formation. The differential gene expression was investigated at the level of m RNA amounts using c DNA probes hybridizing with malate synthase m RNA, isocitrate lyase m RNA, and glycollate oxidase m RNA. Hybrid ization probes were obtained from a c DNA library complementary to the germinationspecific m RNA s of cucumber cotyledons. The process of replacem ent of glyoxysomal proteins by leaf peroxisom al proteins was reversed to a certain extend when greened cotyledons were brought back in the dark. Hybridization on Northern b lots provided evidences that in greened cotyledons the amount of malate synthase m RNA and isocitratelyase m RNA starts to increase up on dark treatment.
Alkaloid Composition of Lupinus albescens (Fabaceae) from South America
Authors: Planchuelo-Ravelo A. M , Wink M. 
Published: August 2018

Abstract
Alkaloid extracts of leaves and seeds of the South American taxon Lupinus albescens Hooker & Arnott were analyzed by capillary gas-chromatography (G LC ) and G LC-mass spectrometry. Multiflorine and albine figured as major, and ammodendrine, lupanine, 11,12-seco-12,13-didehydromultiflorine 13a-hydroxyultiflorine and 13-tigloyloxymultiflorine as minor alkaloids. Three new alkaloids were tentatively identified as a dehydromultiflorine, N -formylalbine and 13-methoxymultiflorine.
Hysteresis and Reversible Cold-Inactivation of ADP-Glucose Pyrophosphorylase From Barley Seeds
Authors: Kleczkowski Leszek A. , Villand Per , Olsen Odd-Arne 
Published: August 2018

Abstract
ADP-glucose pyrophosphorylase (AGP) from barley (Hordeum vulgare L.) seed endosperm showed a lag in activity when assayed after storage at -20 °C. The cold-stored enzyme could regain most, or all, of its activity during 40-60 min following exposure to ambient tempera­tures. The lags were not observed when 2 mM MgCl2 was added to the storage buffer before freezing. Storage at -20 °C, in the absence of MgCl2, led to the appearance of a low activity A GP form which was activated up to 3-fold by 3-phosphoglycerate (PGA) and had high Km values with ATP of 0.3 and 1.2 mM (with and without PGA, respectively). In contrast, storage at -20 °C in the presence of MgCl2 or incubation at +20 °C resulted in an active enzyme which was only weakly activated by PGA (up to 30%) and had the respective Km values with ATP of 0.1 and 0.3 mM . It is suggested that low temperature may induce a change in the conformation and/or oligomerization state of the AGP protein, resulting in a low activity enzyme form which has distinct regulatory and kinetic properties.
Preferential Deactivation of the S3 State of the Water-Oxidizing Complex, Favoured by Plastoquinone Reduction in Barley Chloroplasts
Authors: Franck Fabrice , Schmid Georg H. 
Published: August 2018

Abstract
Departement de Botanique, Service de Photobiologie, Universite de Liege, Sart-Tilman, Belgium and Georg H. Schmid
Triterpenes and a Novel Natural Xanthone as Lipophilic Glandular Products in Hypericum balearicum
Authors: Wollenweber Eckhard , Dörr Marion , Roitman James N. , Arriaga-Giner F. Javier 
Published: August 2018

Abstract
Leaves and young twigs of Hypericum balearicum L. exhibit lipophilic glandular products that can be re­ covered by rinsing green aerial parts with acetone. Major components of the resinous material are the triterpenes lupeone and lupeol. The intensely yellow col­ our of the acetone solution is due to a novel natural product, identified as 1,2,5-trihydroxyxanthone.
Lipogenic Enzymes of Rat Liver and Adipose Tissue. Dietary Variations and Effect of Polychlorinated Biphenyls
Authors: Boll Meinrad , Weber Lutz W. D. , Stampfl Andreas , Messner Burkhard 
Published: August 2018

Abstract
The lipogenic enzymes fatty acid synthase (FAS; EC 2.3.1.85), citrate cleavage enzyme (CCE; EC 4.1.3.8), malic enzyme (ME; EC 1.1.1.40), glucose-6-phosphate dehydrogenase (G6PDH; EC 1.1.1.49) and 6-phosphogluconate dehydrogenase (PGDH; EC 1.1.1.44) were investigated in liver and in brown adipose tissue (BAT) of Wistar rats under various dietary conditions and in the presence of 15 to 250 ppm (approximately 0.045-0.75 μmol/kg chow) polychlorinated biphenyls (PCBs).
In response to refeeding starved animals, enzyme activities in both tissues increased to above normal levels and thereafter exhibited pronounced oscillations of their activities. The extent of increase depended on the carbohydrate and fat content of the diet. The lipogenic enzymes could be grouped in two categories according to their sensitivity to dietary carbohydrate: FAS and CCE responded faster to smaller changes in dietary composition, while ME, G6PDH and PGDH required larger changes and more time to respond.
Diet-induced alterations of enzyme activities were of the same order of magnitude in liver and BAT. They were age-dependent, being more pronounced in young animals. Independent of the type of dietary manipulations, activities changed in a coordinate fashion, i.e., the changes of the activities of all 5 enzymes occurred at similar ratios to each other with an identical time course.
Feeding PCB-containing diets resulted in a considerable increase of the activities of the lipogenic enzymes in liver, which was significantly greater with ME, G 6PD H and PGDH. The effect was dose-dependent but transient. In liver the response to PCB feeding was iden­tical in male and female animals, whereas in BAT lipogenic activities increased in females, but decreased in males.
Refeeding starved animals with a PCB-containing diet led to an additional stimulation of the normal refeeding-induced increase of the enzyme activities in liver and BAT. This PCB-induced increase was 2-fold for FAS and CCE, but up to 15-fold for the other enzymes. All PCB-induced effects were significantly less pronounced in old than in young animals.
In primary hepatocytes activities increased in hormone-free medium in the presence of PCBs. While activity was induced in insuline-and triiodothyronine-containing medium, this increase was significantly greater with PCBs present.
Effect of Modification of Arginine Residues on the Activity of Soybean Lipoxygenase-1
Authors: Matsui Kenji , Shinta Hiroyuki , Kajiwara Tadahiko , Hatanaka Akikazu 
Published: August 2018

Abstract
Arginine residues of soybean lipoxygenase-1 was modified with an arginine-directed chemical modifier, 2,3-butanedione. Although inactivation was not visible if the enzyme reaction was monitored under the standard assay condition (83.3 μᴍ linoleic acid dispersed in 200 mᴍ sodium borate, pH 9.0), rapid inactivation was observed with 5 mᴍ sodium borate, pH 8.0. The inactivation was protected by the addition of a substrate, linoleic acid, in the modification mixture. Kinetic analyses indicated that one arginine residue accounted for the inactivation. Enzymological analyses showed that the modification narrowed the pH-activity profile of L-1 and made L-1 sensitive to salt concentration of the assay solution. Strong inactivation by modification was found at low salt concentration and low pH. This was not due to a physical change of the linoleic acid. On the other hand, product specificity of L-1 was not altered after modification. Taken together, the modified arginine residue(s) was thought to be not essential to the catalysis but have an important role in supporting an ideal electrostatic interaction within L-1 and/or between L-1 and a substrate even in sub-optimal reaction conditions.
Why 43 Codons?
Authors: Ferreira Ricardo 
Published: August 2018

Abstract
An attempt is made to answer the question posed by the title of this paper. First we show that in primitive self-replicating oligoribotide systems, selection depended from the very start on the existence of 4 kinds of ribotides, forming 2 complementary pairs. Further selection required that the condensation reactions involving the two last positions of the 3′-end of a growing oligoribotide fragment and the first position of the 5′-end of another fragment were catalyzed by randomly synthesized peptides. This established a codon - amino acid concen­tration correlation and clinched triplet segments as the basis of the translation process. Finally, physical arguments are given to show that the monochirality of the ribotides arose from stereochemical reasons, as firstly described by Wald, but that of the amino acids is the result of natural selection acting during the peptide-assisted stage of oligoribotide growth.
4-Pentadecylpyridine: A Metabolite from Taphrina pruni
Authors: Fuchs Claus T , Spiteller Gerhard 
Published: August 2018

Contrary to normal fruit, plums infected with Taphrina pruni show various disease symptoms. A comparative study of chemical constituents has proved, by means of GC and GC/MS. that only infected plums contain 4-penta-decylpyridine. Its structure was confirmed by synthesis: a phosphinenickel complex catalyzed the reaction between 4-bromopyridine and penta-decylmagnesium bromide.
Extraction and chromatography of the cultivated fungus have demonstrated that the com­pound is a fungal metabolite.
Relationship between Activities of Enzymes for the Removal of O2
·- and H2O2 and Nitrogenase in Root Nodules of Phaseolus vulgaris L.
Authors: Epping Bernhard , Hansen Alexander P. , Martin Peter 
Published: August 2018

Abstract
Nodules of Rhizobium leguminosarum bv. phaseoli in symbiosis with Phaseolus vulgaris were compared with regard to their nitrogenase activity and activities of enzymes involved in the removal of O2·- and H2O2 as well as total ascorbate content. Activities of catalase (EC 1.11.1.6), ascorbate peroxidase (EC 1.11.1.11), and total ascorbate content were consist­ently higher in nodules inhabited by bacterial strains with higher nitrogenase activity. Values for superoxide dismutase (EC 1.15.11), and guaiacol peroxidase activity did not differ for the bacterial strains compared. On the other hand, when different plant cultivars were inoculated with the same bacterial strain, high nitrogenase activity did not correlate with a higher activ­ity of the oxygen scavenging enzyms or a higher content of total ascorbate. In this case, values for guaiacol peroxidase activity were greatly enhanced in nodules with lower nitrogen­ ase activity. This may be part of a hypersensitive reaction of the plant cultivar against the bacterial symbiotic partner.
Inhibition of catalase activity in the nodules by addition of triazole to the nutrient solution did not alter nitrogenase activity within the first nine hours after addition. It can be concluded that the activity of catalase, ascorbate peroxidase, and superoxide dismutase is not generally coupled to nitrogenase activity in root nodules of P. vulgaris.
A Receptor Interaction Model for Phenylcarbamate Local Anesthetics
Authors: Kettmann V. , Sivý J. 
Published: August 2018

Abstract
We report here a molecular modeling study of selected conformationally constrained phenylcarbamate local anesthetics in relation to the available pharmacological data that enabled us to develop a receptor-interaction model for this class of drugs. The validity of the model was confirmed on other semirigid analogues prepared for this study. The results suggest that the phenyl ring is most likely involved in a stacking interaction with a complementary receptor site and the tertiary ammonium group is capable of both hydrogen bonding and lipophilic interactions.
Electron Spin Resonance Study of Semiquinones Formed during the Autoxidation of 6-Hydroxy-dopamine (2,4,5-Trihydroxy-phenyl-ethylamine)
Authors: Köhle Heidrun , Schuler Paul , Stegmann Hartmut B. , Roginsky Vitaly A. , Brucheltc Gernot 
Published: August 2018

Abstract
6-Hydroxy-dopamine is easily oxidized in aqueous solutions within a pH range of 7-14. Depending on this parameter and the starting concentration of this catechol at least seven different paramagnetic species can be detected. Cyclization to two different indole derivatives of aminochrome type could be demonstrated and the mechanism of formation is discussed. The indoloquinones can easily be reduced to the corresponding semiquinone by an excess of 6-hydroxy-dopamine. All radicals observed react with ascorbic acid in a redox reaction, forming the corresponding catechol and the ascorbic acid semidione
Effect of Platinum(II) Complexes of Benzoic and 3-Methoxybenzoic Acid Hydrazides on Saccharomyces cerevisiae
Authors: Tabakova Svoboda , Dodoff Nicolay 
Published: August 2018

Abstract
The inhibitory effect of benzoic acid hydrazide (bah) and 3-methoxybenzoic acid hydrazide (mbah) on Saccharomyces cerevisiae strains has been compared to that of their platinum(II) complexes: cis-[Pt(bah)2X2], cis- [Pt(NH3)(bah)Cl2]-0.5 H2O. cis-[Pt(mbah)2X2] and cis- [Pt(NH3)(mbah)Cl2] (X = Cl, Br = I), and cis- [Pt(NH3)2Cl2]. The minimal inhibitory concentrations for bah and mbah were 5000-20.000 μm whereas for their Pt(II) complexes they were much less (25-800 jam) and did not exceed these of cisplatin (100-800 μm ) . The activity of the Pt(II) complexes of bah and mbah varied in wide ranges for the different yeast strains tested. Osmotically unstable mutants were found to be more susceptible. The most active complexes were [Pt(NH3)(bah)Cl2] · 0.5 H2O and [Pt(NH3)(mbah)Cl2
Chemical Structure-Odor Correlation in Series of Synthetic Methylene Interrupted n-Nonadien-1-ols
Authors: Sakoda Yasunobu , Matsui Kenji , Akakabe Yoshihiko , Suzuki Jun , Hatanaka Akikazu , Kajiwara Tadahiko 
Published: August 2018

Abstract Chemical structure-odor correlations in the isomers of n-C9-methylene interrupted dienols were explored using synthetic nine isomers of these alcohols. The synthetic dienols were purified by recrystallization or column chromatography of their 3,5-dinitrobenzoate de­ rivatives.
Chemical structure-odor correlations in all the isomers of the purified n-nonadien-1-ols were analyzed by treating the data obtained statistically with the principal component analysis method (Sakoda et al., 1995; Cramer et al., 1988) in comparison with those of n-nonen-1-ols. The odor profiles of the n-nonadien-1-ols were attributable largely to the geometries of the isomers, compared with n-nonen -1-ols (Sakoda et al., 1995). With the principal component analysis, the odor profiles of the series of the dienols were successfully integrated into the first and the second principal components. The first component (PC 1) consisted of combined characteristics of fruity, fresh, sweet, herbal and oily-fatty, and the second component (PC 2) leaf or grassy and vegetable-like. Of the methylene interrupted dienol isomers, (2E ,6Z)-and (3Z,6Z)-nonadien-1-ols which are natural products and have (6Z) in the same, deviated markedly from the other isomers as seen in (6Z)-nonen -1-ol of n-nonen-1-ols. That suggests that the double bond of (ω3Z) was an important factor for natural characteristic odor.
Lipoxygenases in Plants -Their Role in Development and Stress Response
Authors: Rosahl Sabine 
Published: August 2018

Abstract
Lipoxygenases catalyze the hydroperoxidation of polyunsaturated fatty acids and thus the first step in the synthesis of fatty acid metabolites in plants. Products of the LOX pathway have multiple functions as growth regulators, antimicrobial compounds, flavours and odours as well as signal molecules. Based on the effects of LOX products or on the correlation of increases in LOX protein and the onset of specific processes, a physiological function for LOXs has been proposed for growth and development and for the plant response to patho­gen infection and wound stress.
Magnesium Starved Cells of Euglena gracilis - a Possible Model System for Studying Mg2+ Influx?
Authors: Scholten-Beck Gabriele 
Published: August 2018

Abstract
In order to obtain a model which allows to directly study Mg2+ influx into the cell, Mg2+ deficiency was induced in the unicellular photoautotrophic flagellate Euglena gracilis. Lack of Mg2+ in the culture medium leads to a number of morphological, biochemical, and physio­ logical changes in E uglena gracilis. The rate of cell division was reduced under Mg2+-free conditions. Subsequently an enlargement of the cells was observed and they changed from spindle-like to oval shape. The Mg2+-starved cells were well filled with paramylon granules, while their motility and vitality was not impaired. Concurrently with the larger cell size the protein-, carbohydrate-, and chlorophyll content of the cells increased. Further changes were observed in the surface carbohydrates. The proportion of cells with galactose, N-acetyl-galac-tosamine and mannose on the cell surface rose in the Mg2+-starved cultures, shown in a lectin-binding assay. Fucose was found on the pellicle of Mg2+-starved cells only. Cultivation of E uglena gracilis in Mg2+-free medium induced a drastic reduction of the intracellular Mg2+ concentration already after 24 h (from 233 nmol/106 cells to 82 nmol/106 cells). When Mg2+ was made available again, the Mg2+-starved cells took them up rapidly and the intracellular concentration of free Mg2+ rose. As Mg2+ depletion could be induced in Euglena gracilis easily by manipulating the culture conditions and as the cells remained viable, it was con­ cluded that this flagellate can be used as a model organism for studying the Mg2+ uptake of eukaryotic cells.