bluuebunny/crossref_metadata_2025_split huggingface dataset:
Lipid and Fatty Acid Composition of Synchronized Synechococcus leopoliensis
Authors: Döhler Günter , Datz Günter 
Published: August 2018

Abstract
The cyanobacterium Synechococcus leopoliensis (Anacystis nidulans, strain L 1402-1) grown at 39 °C and 2 vol. % CO : could be synchronized by a light/dark regime of 3:5 h (white light intensity 1.5 × 104 erg cm-2 sec-1). Content of pigments (chlorophyll a. phycocyanin and carotenoids), R N A and proteins increased linearly up to 100% at the end of the light period while DNA synthesis was lower. Chlorophyll a synthesis was correlated to the photosystem I activity of the isolated thylakoids and to the formation of MGD G . Galacto lipids were synthesized in the light period, only. A lag phase of 2h was observed in the biosynthesis of SQDG and PG. No significant differences were found between the cell and thylakoid fractions. Palmitic (C16:0), hexadecenoic (C16:1) and octadecenoic (C18:1) acid as major com ponents accounted for more than 90% of total fatty acids in MGD G , DGDG and SQDG . PG contains a small amount of stearic (C18:0) and heptadecenoic (C17:1) acid. No significant variations in the fatty acid distribution of all lipids could be detected in the cell fraction during the division cycle. Changes in the ratio of saturated to unsaturated fatty acids were found in isolated thylakoids. only. In experiments with [14C]bicarbonate main radioactivity was measured in galacto lipids while using [14C]acetate SQDG and PG were markedly [14C]labelled. Results were discussed with reference to the findings of eucaryotic algae and the formation of photosynthetic membranes.
Oxidative Ring-Cleavage of Catechol in meta-Position by Superoxide
Authors: Müller Rudolf , Lingens Franz 
Published: August 2018

Abstract
Superoxide reacts with catechol in dimethylsulfoxide to form a yellow product. The structure of this product was established by different methods. UV-spectra of the yellow compound corresponded under all circumstances to those of enzymatically produced 2-hydroxymuconic acid semialdehyde. In the presence of ammonia the product was converted to picolinic acid. The UV - spectra, the retention times in GC and HPLC and the mass spectra after methylation corresponded to those of authentic picolinic acid. Thus, the yellow reaction product was unequivocally identified as 2-hydroxymuconic acid semialdehyde. The formation of the me/a-cleavage product was only observed at low catechol concentrations (<2 mM) , at higher concentrations the product was not formed. The reaction was complete within 10 min at room temperature. Spectroscopic data suggest a first intermediate in the reaction with λmax = 804 nm, 772 nm and 660 nm.
New Hexaketides Related to Sordariol in Sordaria macrospora
Authors: Bouillant Marie Louise , Bernilion Jacques , Favre-Bonvin Jean , Salin Nadia 
Published: August 2018

Abstract
Broths extracts of the fungus Sordaria macrospora afforded new hexaketides related to sordariol: sordarial, the corresponding aldehyde, heptacyclosordariolone and cyclosordariolone, two cyclic compounds. The structure of these substances has been established by spectrometric methods.
Notes: Specificity of anti-MHC Class II Antibody Binding to Synthetic Peptides
Authors: Chersi Alberto , Romano Teresa F. , Ruocco Emilio 
Published: August 2018

Abstract
This study indicates that antibodies raised against a DR4 , w6; DQw 1,3 positive cell line may bind to synthetic peptides selected from the polymorphic amino acid se­quences 51 -59 and 63 -79 on the DQw 2 beta chain. This cross-reaction may be explained by the relatively high sequence homology of these sequences in the beta chains of class II histocompatibility antigens, and suggests that anti­ body binding to small peptides may be scarsely selective. Based on the observations of the reactivity of the anti­ bodies with several cell lines, and comparison of the amino acid sequences of beta chains of DR and DQ molecules, an attempt to identify the cross-reacting epitope is presented.
Photoinactivation of Photosystem II and Degradation of the D1 Protein are Reduced in a Cytochrome b6/f -Less Mutant of Chlamydomonas reinhardtii
Authors: Shochat Susana , Adir Noam , Gal Alma , Inoue Yorinao , Mets Laurence , Ohad Itzhak 
Published: August 2018

Abstract
The effect of unoccupancy of the QB site by plastoquinone on the photoinactivation of reaction center II in a Cyt b6/f-less mutant of Chlamydomonas reinhardtii, B6, was investigated. In these cells the oxidation of plastoquinol generated by electron flow via RC II to plastoquinone and thus the turnover of PQH2/PQ via the QB site are drastically reduced. Reaction center II of the mutant cells was resistant to photoinactivation relative to the control cells as demonstrated by measurements of light-induced destabilization of S2-QB charge recombination, rise in in­ trinsic fluorescence and loss of variable fluorescence. These parameters relate to functions in­ volving the reaction center II D1 protein. The light-induced degradation of D1 in the mutant cells was also considerably reduced, with a t 1/2 value of 7 h as compared, under similar conditions, to about 1.5 h for the control cells. These results indicate that the photoinactivation of RC II and turnover of the D1 protein are related and require occupancy of the QB site by PQ and its light-driven reduction.
Free Radical Scavengers Inhibit Light-Dependent Degradation of the 32 kDa Photosystem II Reaction Center Protein
Authors: Sopory Sudhir K. , Greenberg Bruce M. , Mehta Roshni A. , Edelman Marvin , Mattoo Autar K. 
Published: August 2018

Abstract
Involvement of oxygen-free radicals in the rapid, light-dependent degradation of the 32 kDa photosystem II reaction center protein was investigated. The free radical scavengers propyl-gallate and uric acid inhibited 32 kDa protein degradation without affecting linear electron flow. The involvement of singlet oxygen was excluded. Protection from degradation was also afforded under ultra-violet and far-red radiations. These data implicate free-radical damage as a common step in the degradation process, and emphasize the oxygen environment as a causative factor in destabilization of the 32 kDa protein.
Conserved Kinetics at the Reducing Side of Reaction-Center II in Photosynthetic Organisms; Changed Kinetics in Triazine-Resistant Weeds
Authors: Jansen Marcel A. K. , Pfister Klaus 
Published: August 2018

The decay of chlorophyll variable fluorescence after a “single turnover” flash is generally assumed to represent the reoxidation of the reduced quinone Qa. We have observed that the kinetics of this decay are very similar in a wide variety of species. Comparing 28 different species, we found an average half decay time of 314 ± 46 μsec. No systematic correlations were found between the decay rate and biochemical or physiological specializations such as C2, C4 or CAM. This indicates that structural as well as functional factors controlling photosystem II electron transfer between Qa and Qb are highly conserved. Apparently, the freedom for natural structural variations in this region is very limited.
Triazine resistant plants, characterized by an altered amino acid sequence of the D1 protein, have clearly decreased rates of Qa/Qb electron transfer. We found an average half decay time of 946 ± 100 (isec (5 species). However, this three-fold decrease is much less than previously reported. Therefore, if alterations of photosystem II electron transfer efficiency contributes to an often reported reduction of “ecological fitness”, this contribution is smaller than was hitherto assumed.
Differential Pleiotropy in a psbA Gene Mutant of Brassica napus Implies Altered Temporal Photosynthesis and Thermal Tolerance
Authors: Dekker Jack , Burmester Ronald G. 
Published: August 2018

Abstract
Studies were conducted to test the hypothesis that the mutation to the psbA. plastid gene that confers s-triazine resistance (R) also results in an altered diurnal pattern of photosynthetic carbon reduction (CER) relative to that of the susceptible (S) wild-type. In all experiments CER approximated the increasing and decreasing light levels during the diurnal. S C ER exceeded that of R during the midday period, but R CER was greater early and late in the diurnal at 25 °C. R CER exceeded that of S for most of the diurnal at 35 °C and in older, crowded, nitrogen-starved plants. These studies support the stated hypothesis and indicate a more complex model of photosynthetic productivity than previously observed. An assessment of the photosynthetic competence of either biotype may be a function of the time of day or the environmental conditions the plants are exposed to, especially temperature.
Elicitor Recognition and Signal Transduction in Plant Defense Gene Activation
Authors: Scheel Dierk , Parker Jane E. 
Published: August 2018

Abstract
Plants defend themselves against pathogen attack by activating a whole set of defense responses, most of them relying on transcriptional activation of plant defense genes. The same responses are induced by treatment of plant cells with elicitors released from the pathogen or from the plant surface. Several plant/elicitor combinations have been used successfully as experimental systems to investigate the molecular basis of plant defense responses. Receptor-like structures on the plasma membrane of plant cells appear to bind the elicitors. Thereby, intracellular signal transduction chains are initiated which finally result in the activation of plant defense genes. A better understanding of the molecular mechanisms of early processes in plant defense responses, as provided by these studies, may in the long term help to develop environmentally safe plant protection methods for agriculture.
Porin of Rhodobacter capsulatus: Biochemical and Functional Characterization
Authors: Woitzik Daniela , Weckesser Jürgen , Benz Roland , Stevanovic Stefan , Jung Günther , Rosenbusch Jürg P. 
Published: August 2018

Abstract
The major outer membrane protein of Rhodobacter capsulatus 37 b4 (capsule-free) was iso­lated. Strong porin-activity was observed after reconstitution into artificial lipid bilayer mem­branes with a single channel conductance of 3.15 nS in Im KC1. The porin migrated as a broad, single band (Mr above 90,000) on sodium dodecyl sulfate polyacrylamide gel electro­ phoresis and dissociated into a single species of polypeptides (Mr 36,000) on treatment with EDTA (10 mM at 30 °C, 20 min) or by heating (100 °C, 5 min). Analytical ultracentrifugation studies demonstrated the native porin to be a trimer. The monomers chromatofocused as a single, sharp peak on fast performance liquid chromatography and only one band, corre­ sponding to an isoelectric point of about 4.0, was obtained on isoelectric focusing. Gas-phase sequencing of the 23 N-terminal residues revealed Glu-Val-Lys-Leu-Ser-Gly-Asp-Ala-Arg-Met-Gly-Val-Met-Tyr-Asn-Gly-Asp-Asp-X-Asn-Phe-Ser-Ser.
The Biflavonoid Pattern of Rhytidiadelphus squarrosus (Hedw.) Warnst.
Authors: Seeger Tassilo , Zinsmeister Hans Dietmar , Geiger Hans 
Published: August 2018

Abstract
From Rhytidiadelphus squarrosus the hitherto unknown biflavone 5′-hydroxyrobustaflavone and the three known biflavonoids 5′-hydroxyamentoflavone,5′,3′′′-dihydroxyamentoflavone and 2,3-dihydro-5′-hydroxyamentoflavone have been isolated.
Phenolic Composition of Bud Exudates of Populus deltoides
Authors: Greenaway W. , English S. , Whatley F. R. 
Published: August 2018

Abstract
Bud exudate of Populus deltoides clones originating from six central and eastern American states was examined by gas chromatography/mass spectrometry and the components were identified. The principal components of the bud exudate were the flavone galangin, the flavanone pinocembrin and the flavanonol pinobanksin, together with the related compounds pinocembrin chalcone, pinobanksin methyl ether and pinobanksin-3-acetate. The bud exudate composition was very different from that seen in a North American poplar of the section Tacamahaca, P. balsamifera.
The bud exudates from all P. deltoides specimens were similar excepting that from Vermont.
UVA-Induced Genetic Effects of Thioridazine, Mesoridazine and Sulforidazine: an in vitro Study
Authors: Schoonderwoerd Simon A. , van Henegouwen Gerard M. J. Beijersbergen , Panday Ivan R. 
Published: August 2018

Abstract
This in vitro study focuses on the UVA-induced reactions with DNA of thioridazine (TRZ), and two of its major metabolites (TRZ-2-sulfoxide or mesoridazine, MRZ ; and TRZ- 2-sulfone or sulforidazine, SRZ). TRZ binds covalently to DNA upon UVA-irradiation. Under comparable irradiation conditions, MRZ binds to a lesser extent and almost no binding was observed with SRZ. Besides, photo-induced genetic effects were investigated by means of a differential DNA repair test in E. coli. The photo-induced genetic effects in E. coli decreased from TRZ, MRZ to SRZ, which corresponds with their capacity for UVA-induced binding to DNA. TRZ, MRZ and SRZ differed in their rate of photodecomposition rather than in the intrinsic reactivity towards DNA of the instable intermediates formed.
Irreversible binding to DNA was also observed upon treatment with peroxidase, which is known to oxidize phenothiazines via the formation of reactive radical cation species. As both the colour of the intermediate and its reactivity towards DNA were comparable for peroxidase treatment and exposure to UVA, we assume that the radical cation is the reactive species in the latter case as well.
Stimulation of Calmodulin Binding to Skeletal Muscle Membrane Proteins by 1,25-Dihydroxy-Vitamin D 3
Authors: Massheimer Virginia , Fernandez Luis M. , de Boland Ana R. 
Published: August 2018

Abstract
Previous work has shown that 1,25-dihydroxy-vitamin D 3 rapidly increases calmodulin levels of skeletal muscle membranes without altering the muscle cell calmodulin content. Therefore, the effects of the sterol on the binding of calmodulin to specific muscle membrane proteins were investigated. Soleus muscles from vitamin D-deficient chicks were treated in vitro for short intervals (5-15 min) with physiological concentrations of 1,25-dihydroxy-vitamin D3. Proteins of mitochondria and microsomes isolated by differential centrifugation were separated on sodium dodecyl sulfate polyacrylamide gels. Calmodulin-binding proteins were identified by a [125I]calmodulin gel overlay procedure followed by autoradiography. 1,25-Dihydroxy- vitamin D3 increased the binding of labelled calmodulin to a major, calcium-independent, calmodulin-binding protein of 28 Kda localized in microsomes, and to minor calmodulin- binding proteins of 78 and 130 Kda proteins localized in mitochondria. The binding of [125I]calmodulin to these proteins was abolished by flufenazine or excess non-radioactive calmodulin. 1,25-Dihydroxy-vitamin D3 rapidly increased muscle tissue Ca uptake and cyclic AM P levels and stimulated the phosphorylation of several membrane proteins including those whose calmodulin-binding capacity potentiates. Analogously to the sterol, forskolin increased membrane calmodulin content, calmodulin binding to the 28 Kda microsomal protein and 45Ca uptake by soleus muscle preparations. Forskolin also induced a similar profile of changes in muscle membrane protein phosphorylation as the hormone. These results suggest that 1,25- dihydroxy-vitamin D 3 affects calmodulin distribution in muscle cells through cyclic AMP-dependent phosphorylation of membrane calmodulin-binding proteins. These changes may play a role in the stimulation of muscle Ca uptake by the sterol.
Bestimmung der relativen Flüchtigkeit von Sexualpheromonen von Schmetterlingen mittels Closed Loop Stripping* / Determination of Relative Volatility of Lepidoptera Sex Pheromones by Closed Loop Stripping
Authors: Bestmann Hans Jürgen , Erler Joachim , Vostrowsky Otto 
Published: August 2018

Abstract
By means of closed loop Stripping the relative evaporation rates of monounsaturated C10-C16-acetates and C10-C12-alcohols have been determined. The results of stimulus released demonstrate the different volatilities of pheromone compounds which should be taken in account with certain biotests and physiological studies.
Growth and Terpenoid Production of an Axenic Culture from the Liverwort Ricciocarpos natans
Authors: Wurzel Gerald , Becker Hans 
Published: August 2018

Abstract
Ricciocarpos natans grows best on Gamborg B5 medium supplemented with 2% sucrose. Six other mineral media were less effective on the growth. During a culture period, pH of the media changed depending on the ammonium and nitrate content of the respective media. In media of a molar ratio of ammonium to nitrate of 1:1 or 1:1.9, pH first dropped from 6.0 to about 3.5 and then rose again. In media where nitrate is the only nitrogen source or where there is a ratio of ammonium to nitrate of 1:12.5, pH rose during the first two weeks and after this dropped. Differences in the light intensity (2000 an d 6000 lx) and light regime (14 h light/ 10 h dark) had no effects on the growth. The cultures produced a variety of terpenoids. The same pattern of compounds was seen in field-collected material as well as in cultivated material. The content of the terpenoids decreased on nitrogen and phosphorous-deficient media.
Hysteresis and Reversible Cold Inactivation of Maize Phosphoenolpyruvate Carboxylase
Authors: Kleczkowski Leszek A. , Edwards Gerald E. 
Published: August 2018

Abstract
Maize (Zea mays L.) leaf phosphoenolpyruvate (PEP) carboxylase (PEPCase) (EC 4.1.1.31) showed a lag in activity when assayed after storage at 0-4 °C. The lag was promoted by high pH on storage (7.8 -8.5) and was observed over a range of assay pH (7.1 -8.5). Thermal reacti­vation of the cold-stored enzyme by assay temperature (18 °C) accounted for most of the hysteretic effect, but presence of PEP in the reaction mixture was required to completely eliminate the lag. Based on steady-state rates after the lag, stability of PEPCase in the cold was inde­pendent of protein concentration . It is suggested that low temperature and high pH induce a change in the oligomerization state of PEPCase, resulting in a less active but relatively stable form of the enzyme. The lag probably reflects a reversal of this process, promoted by assay temperature and presence of PEP.
Organ Specific Storage of Dietary Pyrrolizidine Alkaloids in the Arctiid Moth Creatonotos transiens
Authors: Egelhaaf A. , Cölln K. , Schmitz B. , Buck M. , Wink M. , Schneider D. 
Published: August 2018

Abstract
Larvae of the arctiid moth Creatonotos transiens obtained each 5 mg of heliotrine, a pyrrolizidine alkaloid, via an artificial diet. 7 S-H eliotrine is converted into its enantiomer, 7 R1-heliotrine, and some minor metabolites, such as callimorphine. 7 S- and 7 R-heliotrine are present in the insect predominantly (more than 97%) as their N-oxides. The distribution of heliotrine in the organs and tissues of larvae, prepupae, pupae and imagines was analyzed by capillary gas-liquid chromatography. A large proportion of the alkaloid is stored in the integument of all developmental stages, where it probably serves as a chemical defence compound against predators. Female imagines had transferred substantial amounts of heliotrine to their ovaries and subsequently to their eggs; males partly directed it to their pheromone biosynthesis.
Closure of a Rapidly Exchanging Calcium Compartment in Rat Cardiac Myocytes by Lanthanum
Authors: Hartl Christoph , Fischer Sabine , Hasselbach Wilhelm 
Published: August 2018

Abstract
Enzymatically isolated myocytes from adult rats were used to measure 45Ca-uptake from salt media of reduced Ca2+-content (0.1 mM) with normal (4 mM) or elevated (20 mM) potas­sium concentrations. Ca2+-uptake was interrupted by filtration followed by rapid chasing the filter with salt solutions containing no Ca2+, 2 mM Ca2+ or 2 mM La3+.
Rate and extent of 45Ca-uptake of resting cells were found to be 3-fold enhanced when chas­ing was performed with La3+-containing media. In contrast La3+ does not affect Ca2+-exchange of depolarized cells, the fluxes of which approximate rates sufficiently high for contraction activation and that are sensitive to Ca2+-channel blockers. The effect of La3+ on resting cells suggests the existence of a small rapidly exchanging La3+-sensitive Ca2+-compartment lo­cated adjacent to the plasma membrane. This compartment is though to be either closed or has become La3+-insensitive in activated cells. The subsarcolemmal cysternae of the SR, the so-called “peripheral couplings” are most likely the morphological substrate of this compart­ment.
Sclerotization of Insect Cuticle in a Cell-Free System
Authors: Agrawal Om P. , Scheller Klaus 
Published: August 2018

Abstract
Incubation of deproteinized larval cuticle (chitin flakes) with purified arylphorin (calliphorin) or larval haemolymph of Calliphora vicina resulted in the formation of a chitin-protein complex. Enzymatic oxidation of N-β-alanyldopam ine (NDAB) in the presence of chitin flakes or the chitin-protein complex, resulted in various degrees of cross-linking of NBAD-quinone formed with chitin. This study confirms the involvement of arylphorin in the process of quinone tanning of insect cuticle.
Changes of Acuity during Light and Dark Adaptation in the Dragonfly Compound Eye
Authors: Warrant Eric J. , Pinter Robert B. 
Published: August 2018

Abstract
Intracellular recordings of angular sensitivity from the photoreceptors of Aeschnid dragonflies (Hemianax papuensis and Aeschna brevistyla) are used to determine the magnitude and time course of acuity changes following alterations of the state of light or dark adaptation. Acuity is defined on the basis of the acceptance angle, Δρ (the half-width of the angular-sensitivity function). The maximally light-adapted value of Δρ is half the dark-adapted value, indicating greater acuity during light adaptation. Following a change from light to dark adaptation, Δρ increases slowly, requiring at least 3 min to reach its dark-adapted value. In contrast, the reverse change (dark to light) induces a rapid reduction of Δρ , and at maximal adapting luminances, this reduction takes place in less than 10 sec.
Herbicide Cross-Resistance and Mutations of the psbA Gene in Chlamydomonas reinhardtii
Authors: Wildner Günter F. , Heisterkamp Ursula , Trebst Achim 
Published: August 2018

The resistance against herbicides (inhibitors of the electron accepting side) of photosystem II originates from mutations of the psb A gene, coding for the D 1 or QB binding protein. Each of the five mutants used in the present study had single base changes in the psbA gene that resulted in a unique amino acid substitution at a different residue of the D1 protein (Val-219, Ala-251, Phe-255, Ser-264, Leu-275). The differences of the I50-values in the electron transfer reaction of H2O to dichlorophenolindophenol were used to analyze the correlation of these amino acid residue changes to their impact on the binding of diverse chemical classes of inhibitors. The binding domains on the D1 protein of the inhibitors overlap, but are nevertheless distinct. Even minor changes in the chemical structure of the inhibitors resulted in changes of the resistance toward a specific amino acid residue.
A pattern of response of the inhibitors to the amino acid substitutions evolves that allows easy differentiation between the groups of PS II inhibitors. Two principally different response curves emerge for two different families of PS II inhibitors, that had been proposed earlier already on functional studies with wild types. But the response pattern of newly described inhibitors, like ketonitrile and quinolone derivatives, in the mutants allows to group them with confidence and in turn generalize the phenol type family. In none of the five mutants, studied here, is there a marked cross-resistance to the new phenol type inhibitors. Just the opposite, in several cases, there is negative cross-resistance (or supersensitivity). Because of this response pattern this group of inhibitors cannot be oriented with certainty in the three dimensional folding model of the D1 protein.