bluuebunny/crossref_metadata_2025 huggingface dataset:
Molecular Evolution of H+-ATPases. I. Methanococcus and Sulfolobus are Monophyletic with Respect to Eukaryotes and Eubacteria
Authors: Gogarten Johann Peter , Rausch Thomas , Bernasconi Paul , Kibak Henrik , Taiz Lincoln
Published: August 2018

The classification of methanogenic bacteria as archaebacteria based on 16 s rRNA sequence analysis is currently in dispute. To provide an alternative molecular marker, the polymerase chain reaction technique was used to amplify a 930 bp fragment of Methanococcus thermolithotrophicus genomic DNA corresponding to the catalytic domain of the membrane H+ -ATPase. The deduced amino acid sequence was 54-58% identical to the ~ 70 kDa subunits of Sulfolobus acidocaldarius and the eukaryotic vacuolar-type H+-A T P ase, and only 29% identical to the beta subunit of the eubacterial-type F0F1-ATPases. Interestingly, a highly conserved aspartate residue in the phosphorylation domain of E 1 E 2-A TPases (P-type) is conserved in the Methanococcus sequence, but is absent from all other known vacuolar and F0F1-ATPases. This suggests that the H+-ATPase of M. thermolithotrophicus, like that of M. voltae, may have a phosphorylated intermediate, despite belonging to the vacuolar-type class of proton pumps. Phylogenetic analysis using Felsenstein’s maximum likelihood method and Lake’s evolutionary parsimony method confirmed that the H+- ATPases of the two archaebacteria, Methanococcus and Sulfolobus, when compared to eukaryotic vacuolar-type ATPases and eubacterial F0F1-ATPases, form a monophyletic group.
Inhibition of de novo Fatty Acid Biosynthesis in Isolated Etioplasts by Herbicides
Authors: Kobek Klaus , Lichtenthaler Hartmut K.
Published: August 2018

It is demonstrated that - similar to chloroplasts - etioplasts isolated from leaves of pea (Pisumsativum L.) and oat seedlings (Avena sativa L.) also possess a high capacity for de novo fatty acid biosynthesis starting from [1-14C]acetate. The etioplast system proved to be a suitable test system for inhibitors of de novo fatty acid biosynthesis such as cycloxydim , sethoxydim and diclofop. In contrast to the chloroplast test system , the etioplast system is independent of light and also permits screening of photosynthetic herbicides as potential inhibitors of fatty acid biosynthesis.
Cytostatic Activity of Aeroplysinin-1 against Lymphoma and Epithelioma Cells
Authors: Kreuter M. H. , Bernd A. , Holzmann H. , Müller-Klieser W. , Maidhof A. , Weißmann N. , Kljajić Z. , Batel R. , Schröder H. C. , Müller W.E.G.
Published: August 2018

(±)-Aeroplysinin-1, an optically active 1.2-dihydroarene-1.2-diol. was isolated from the marine sponges Verongia aerophoba (+-isomer) and lanthella ardis (--isomer). For the experiments presented we used the +-isomer from Verongia aerophoba. Here we describe the hitherto unknown biological and pharmacological property of this compound to display pronounced anticancer activity against L5178y mouse lymphoma cells (ED50: 0.5 μm). Friend erythroleukemia cells (ED50: 0.7μm) , human mamma carcinoma cells (ED50: 0.3μm) and human colon carcinoma cells (ED50: 3.0 μm) in vitro. Furthermore, aeroplysinin caused a preferential inhibition of [3H]thymidine (dThd) incorporation rates in L5178y mouse lymphoma cells if compared with murine spleen lymphocytes in vitro. At concentrations between 1.1 and 28.5 μm, the [3H]dThd incorporation rates in L5178y cells were suppressed to 28% -0% but only to 78% -18% in murine spleen lymphocytes. The same differential effect in vitro was found with the following epithelial cells: 14.70 μm of the compound were required to inhibit normal human fibroblasts to 50% , but only 2.9 μm in the assays with human malign keratinocytes or malignant melanoma cells to observe the same inhibitory effect. Moreover, aeroplysinin-1 displayed antileukemic activity in vivo using the L5178y cell/NMRI mouse system; administered at a dose of 50 mg/kg for five consecutive days, the T/C (% ) value was determined to be 338. Preliminary toxicology studies revealed an acute LD50 of 202 mg/kg and a subacute LD50 of 150 mg/kg. Aeroplysinin-1 is neither a direct mutagen nor a premutagen in the umu/Salmonella typhimurium test system.
New Hexaketides Related to Sordariol in Sordaria macrospora
Authors: Bouillant Marie Louise , Bernilion Jacques , Favre-Bonvin Jean , Salin Nadia
Published: August 2018

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.
New Phenolics from Baccharis Leaf Exudate
Authors: Wollenweber E. , Arriaga-Giner F. J. , Rumbero A. , Greenaway W.
Published: August 2018

Several lipophilic phenolics were found in leaf resins of Baccharis species, reported earlier to produce terpenoids and flavonoid aglycones. They were identified by NMR and GC/MS studies, respectively. The structure of 2′,4′β-trihydroxy-6′-methoxychalcone from B. salicifolia was confirmed by synthesis. Phenylethyl caffeate and benzyl caffeate were found in B. sarothroides.
Partial Proteolysis of Rice Phytochrome: Comparison with Oat Phytochrome
Authors: Schendel Rudolf , Tong Zhe , Rüdiger Wolfhart
Published: August 2018

Phytochrome was isolated from etiolated rice seedlings (Oryza sativa L.) by slight modification of the procedure for oat phytochrome. Spectral data of rice phytochrome are comparable with those of oat and rye phytochrome. Controlled proteolysis with endoproteinases Lys-C and Glu-C yielded defined fragments some of which were different for Pr and Pfr. The fragments were identified by comparison with the corresponding fragments of oat phytochrome and by comparison of the amino acid sequences of rice and oat phytochrome. Regions of the peptide chain which are differently exposed in Pr and Pfr were identified. A highly conserved sequence around residues 740-750 is discussed as candidate for an ‘‘active center’’ of signal transduction.
Regeneration des Cortex bei Stentor coeruleus / Regeneration of the Cortex in Stentor coeruleus
Authors: Schwartz Viktor
Published: August 2018

Treatment of Stentor with very acid culture medium (pH 2.8) results in delamination of the cortex from the endoplasm . This procures the possibility to strip off the cortex with all its acid resistant organelles at minimum loss of endoplasm. Acid sensitive organelles react with dissolution or more or less damage. The endoplast may survive giving rise to a thin plasma membrane, which may be (even several times) shed and renewed. 10.5% of the decorticated cells regenerated a complete cortex. The ball-shaped and apparently apolar endoplast may pass through an ameboid stage. The visible part of the regeneration process begins with the appearance of a chaotic line system , which in regaining the polar order turns out to be the pigment free interstripe spaces. The ubiquitous appearing of foot anlagen underline the apolar situation. Nevertheless, the problem of endoplasmic preservation of polarity requires further, presently running, experiments. Obvious polarity begins to restore with the development of first membranelies and - approximately in opposite position with these - the definitive foot develops with the holdfast organelle. The ordering of stripe pattern starts from the foot and proceeds to the cells apex. With respect to Tartar’s contradicting result (death o fall decorticated cells) the new experiments do not refute Tartars conclusions, since the technique is different from his only micro-surgical method. This will be discussed in a following paper in context with the results of some other experiments. The here described total regeneration of the cortex in Stentor is not consummated as cytotactic differentiation depending on preformed structure.
Notes: Specificity of anti-MHC Class II Antibody Binding to Synthetic Peptides
Authors: Chersi Alberto , Romano Teresa F. , Ruocco Emilio
Published: August 2018

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

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

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.
A New Ioxynil-Resistant Mutant in Synechocystis PCC 6714: Hypothesis on the Interaction of Ioxynil with the D1 Protein
Authors: Creuzet S. , Ajlani G. , Vernotte C. , Astier C.
Published: August 2018

A new Synechocystis 6714 mutant, loxIIA, resistant to the phenol-type herbicide ioxynil was isolated and characterized. The mutation found in the psbA gene (encoding the D1 photosystem II protein) is at the same codon 266 as for the first ioxynil-resistant mutant IoxIA previously selected [G. Ajlani. I. Meyer, C. Vernotte. and C. Astier, FEBS Lett. 246, 207-210 (1989)]. In IoxIIA, the change of Asn 266 to Asp gives a 3 × resistance, whereas in IoxIA, the change of the same amino acid to Thr gives a 10 × resistance. The effect of these different amino acid substitutions on the ioxynil resistance phenotype has allowed us to construct molecular models and calculate the hydrogen-bonding energies between the hydroxyl group of ioxynil and the respective amino acids at position 266.
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

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.
Herbicidal Inhibition of Carotenogenesis Detected by HPLC
Authors: Barry Paul , Pallett Ken E.
Published: August 2018

The target sites of three herbicides which inhibit carotenoid biosynthesis have been characterized using HPLC analysis of pigment extracts from two higher plant systems, carrot cell suspension cultures and barley seedlings. Diflufenican causes an accumulation of phytoene and phytofluene. Dichlormate causes accumulation of phytoene, phytofluene, ξ-carotene, neurosporene and β-zeacarotene. Amitrole causes accumulation of phytoene, phytofluene, β- γ- and δ-carotenes and lycopene. Significant differences in the geometric and hydroxylated natures of the accumulated precursors occurred between the carrot cell and dark- and light-grown barley. These differences are discussed with respect to both the target sites of the three carotenogenic herbicides and the biosynthetic pathway leading to carotenoid biosynthesis in higher plants.
Metabolism of Metolachlor by a Microsomal Fraction Isolated from Grain Sorghum ( Sorghum bicolor) Shoots
Authors: Moreland Donald E. , Corbin Frederick T. , Novitzky William P. , Parker Carol E. , Tomer Kenneth B.
Published: August 2018

A microsomal fraction isolated from the shoots of 3- to 4-day-old, dark-grown, grain sorghum (Sorghum bicolor cv. Funk G 522 D R ) seedlings was characterized. The preparations had a cytochrome P-450 content that varied from approximately 90 to 150 pmol P-450/mg protein with cytochrome P-420 varying from 0 to 3% of the P-450 content. Type I difference spectra were formed with cinnamic acid and metolachlor, and a type II spectrum was formed with tetcyclacis. In short-term assays with [14C]metolachlor as substrate, the preparations produced a single time-dependent product that separated on silica gel TLC plates developed in benzene/acetone (2:1, v/v). RF values for metolachlor and the metabolite were approximately 0.70 and 0.48, respectively. The microsomal reaction required N A D P H and oxygen, and was inhibited by carbon monoxide, with the inhibition being partially reversed by actinic light. Compounds known to inhibit the activity of cytochrome P-450 monooxygenases (piperonyl butoxide, tetcyclacis, and tridiphane) also prevented formation of the metabolite. Identity of the metabolite was confirmed by TLC and positive ion thermospray LC/MS to be 2-chloro-N-(2-ethyl-6- methylphenyl)-N-(2-hydroxy-l-methylethyl)acetamide. Hence, the reaction catalyzed by the sorghum microsomes involved O-demethylation of the methoxypropyl side chain of metolachlor.
Elicitor Recognition and Signal Transduction in Plant Defense Gene Activation
Authors: Scheel Dierk , Parker Jane E.
Published: August 2018

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

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

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

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

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

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

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

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

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.
Cellular Amino Acid Concentrations and Regulation of Aspartate Kinase in the Thermophilic Phototrophic Prokaryote Chloroflexus aurantiacus
Authors: Klemme Jobst-Heinrich , Laakmann-Ditges Gisela , Mertschuweit Jutta
Published: August 2018

Aspartate kinase (AK , EC 2.7.2.4) from the thermophilic, phototrophic prokaryote, Chloroflexus aurantiacus, was partially purified and separated from homoserine dehydrogenase (HSDH, EC 1.1.1.3). The molecular weights as determined by gel filtration were 130,000 and 46,000, respectively. HSDH had a moderately high thermal stability (50% inactivation at 84 °C) and displayed its activity optimum at 72 °C. By contrast, AK had its activity optimum at 52 °C (with a break-point in the Arrhenius plot at 42 °C) and was much less thermostable (50% inactivation at 67 °C). The Km-values for aspartate and ATP (determined in a pyruvate kinase-coupled test system) were 10.5 and 0.63 mM , respectively. The enzyme was strongly inhibited by L-threonine (Ki = 10 μm) and activated by alanine, isoleucine, valine and methionine. L-Threonine acted as a mixed-type inhibitor in respect to aspartate, and non-competitively in respect to ATP. Contrary to AKs from Rhodospirillaceae, the enzyme from Chloroflexus aurantiacus was not subject to a concerted feedback inhibition by two amino acids of the aspartate family. The regulatory properties of the aspartate kinase are discussed in relation to the cellular amino acid concentrations.
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

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

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

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

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.
The Sequence of Acheta Adipokinetic Hormone and the Variation in Corpus cardiacum Content and Hyperlipaemic Response with Age
Authors: Woodring Joseph , Das Subrata , Kellner Roland , Gäde Gerd
Published: August 2018

The principle neuropeptide separated by reversed-phase liquid chromatography RP -HPLC from extracts of the corpora cardica of Acheta domesticus showed strong adipokinetic activity when injected into Acheta. The N -terminal pyroglutamate of the peptide was removed by enzymatic digestion, and the remaining peptide sequenced. The structure is identical to the peptide Grb -AKH previously described from the corpus cardiacum (CC) of Gryllus bimaculatus ( pGlu - Val - Asn - Phe - Ser - Thr - Gly - Trp - NH2). The ED50 was (0.8 pmol) and saturation was achieved with injection of 2 pmol of synthetic Grb-AKH . The time to maximum hyperlipaemic response was 90 -120 min. The response of the fat body to injected synthetic Grb- AKH doubled in 4 days during the last stadium , but was never greater than half the maximum response of the adult stage. The adult adipokinetic response doubled from the first to the fourth day then gradually declined through day 16. The increased AKH response was timecorrelated to fat storage in the larvae and to lipid diposits in the oocytes in the adult. Synthetic Grb -AKH activated glycogen phosphorylase in the fat body of Acheta. The amount of Grb- AKH present in the CC changed very little throughout the last larval stadium and through the first 9 days of the adult stage, averaging about 15 pmol/gland pair. A second peptide (a hexadecapeptide) was isolated from the CC of Acheta and sequenced. Its structure is identical to a putative diuretic hormone previously described in Acheta.
Comparative Luminescence of Rat Liver Cu-thionein and Its Chemically Synthesized α-Domain
Authors: Li Yuejin , Zhang Lianshan , Bayer Ernst , Oelkrug Dieter , Weser Ulrich
Published: August 2018

A peptide corresponding to the α-domain of rat liver metallothionein-2 was chemically syn­thesized employing the solid phase peptide synthesis technique. Its luminescence properties that depend on the coordinated Cu(I) have been studied using luminescence spectrometric titration in the presence of Cu(I). Unlike the intact metallothionein which has been converted into the Cu species, the emission and excitation spectra of the Cu-α-fragment showed a red shift by 20 nm and 65 nm, respectively, suggesting a more compact and stable luminophore in the a-domain. Saturation of Cu(I) coordination was reached in the presence of 6.5 mol eq Cu(I) when the α-fragment was used and 12 mol eq Cu(I) were specifically bound by the intact metallothionein. The emission bands were homogeneous and no decline of the cluster struc­ture was observed when excessive Cu(I) was added after saturation. A rearrangement of the Cu-cluster in metallothionein during its formation seems to be plausible.
Automatic Control and Directed Cell Movement Novel Approach for Understanding Chemotaxis, Galvanotaxis, Galvanotropism
Authors: Gruler Hans , Franke Kurt
Published: August 2018

Abstract It is shown that chemotaxis, galvanotaxis, galvanotropism , etc. are functions of cells having a goal-seeking system. Even when the involved physicochemical signals are unknown, the cel­lular system can be treated phenomenologically like an automatic controller having a closed-loop feedback system. The model is verified by means of galvanotaxis and chemotaxis data of human granulocytes. The galvanotaxis and chemotaxis coefficient quantifying the cellular sensi­bility can be predicted from the coefficient which characterizes the deterministic part of the signal transduction/response system of the cell divided by the coefficient which characterizes the noise strength in the cellular signal transduction/response system. The model is not restricted to directed movement of granulocytes. It is very general and can be applied to any cell type for directed phenomena like chemotaxis, galvanotaxis, phototaxis, magnetotaxis, directed growth, etc. The virus-disturbed directed migration of granulocytes is discussed and it is shown that the virus alters the deterministic part of the cellular controller.
Enzymic Properties of Purified Myrosinase from Lepidium sativum Seedlings
Authors: Durham Paul L. , Poulton Jonathan E.
Published: August 2018

To establish the substrate specificity of the thioglucoside glucohydrolase myrosinase (EC 3.2.3.1), this enzyme was purified to homogeneity from light-grown cress (Lepidium sativum L.) seedlings by Sephadex gel filtration. Red Dye and anion exchange (FPLC Mono Q) chro­matography, and preparative isoelectric focusing. Hydrolytic activity was shown toward only 4 of the 29 synthetic and natural O-and S-glycosides tested. Highest activity was displayed with the endogenous glucosinolates benzylglucosinolate (Km, 295 μM) and sinigrin (Km, 300 μM) at an optimum pH of 5.5 in sodium citrate buffer. The synthetic glycosides PNPG (Km, 2.0 mM) and ONPG were poorer substrates at an optimum pH of 6.5 in potassium phos­phate buffer. The enzyme was inactive with all other nitrophenyl glycosides tested including PNP-a-D-glucoside and PNP-thio-β-D-glucoside, suggesting a requirement for O-β-D-glucose as the glycone moiety within these substrates. PNPG hydrolysis was stimulated 2.6-fold by ascorbate (1 mM). The enzyme exhibited no metal ion requirement and was strongly inhibited by lead nitrate, mercury chloride, and ferric chloride at 1 mM concentration. The metal chela­tors DIECA , EDTA , o-phenanthroline, and 2,2′-dipyridyl were not inhibitory, but the thiol reagents PCMS, PCMB, and N-ethylmaleimide (at 1mM) caused 50 -80% inhibition of enzyme activity.
Studies on the Biosynthesis of γ–Decalactone in Sporobolomyces odorus
Authors: Albrecht Wolfgang , Tressl Roland
Published: August 2018

Incubation of racemic ethyl [2,2-2H2]-(E)-3,4-epoxydecanoate and the corresponding acid with intact cells of Sporobolomyces odorus led to the formation of deuterium labeled γ-decalaetone. The detection of labeled 2-decen-4-olide and 4-oxodecanoic acid made it possi­ble to propose the biogenetic sequence leading to γ-decalactone. The determination of the en­ antiomeric ratio of the lactone revealed an unspecific metabolism of the precursor. In contrast to the (E)-isomer, after administration of ethyl [5,6-2H2]-(Z)-3,4-epoxydeeanoate no transfor­mation could be detected. These results indicate that (E)-3,4-epoxydecanoic acid, formed from (E)-3-decenoyl-CoA , an intermediate of the β-oxidation of linoleic acid, is the genuine precur­sor in the biosynthesis of γ-decalactone.
Carnivora: The Amino Acid Sequence of the Adult European Mink (Mustela lutreola, Mustelidae) Hemoglobins
Authors: Ahmed Aftab , Jahan Meeno , Braumtzer Gerhard
Published: August 2018

The complete amino acid sequences of the hemoglobins from the adult European mink (Mustela lutreola) are presented. The erythrocytes contain two hemoglobin components and three globin chains. The isolation of globin chains achieved by ion-exchange chromatography on a column of CM -cellulose in 8 M urea buffer. The primary structure of globin chains and of the tryptic peptides determined in liquid-and gas-phase sequenators. The alignment of the a-and β-chains with those of reported sequences from other carnivora species belonging to the family Mustelidae may give an insight into the evolution of this molecule.
Influence of High Steady Magnetic Fields on the Electrical Activity of the Electric Fish Apteronotus
Authors: Stojan L. , Sperber D. , Dransfeld K.
Published: August 2018

We have investigated the influence of strong dc. magnetic fields - ranging up to 10 Tesla - on the weak sinusoidal electric signals which the electro-fish Apteronotus is known to emit. We made the following observations:

1. The amplitude of the sinusoidal electric signals rises with the application of the dc. magnetic fields, increasing by about 8% in a field of 10 Tesla.

2. The frequency of the signals of about 570 Hz was not at all affected by the field but remained constant in fields up to 10 Tesla.

Since the electric signals of Apteronotus are of neural origin our experiments indicate an influence of strong dc. magnetic fields on the nervous system of this electric fish.
Effect of Antisera to RuBP-Carboxylase/Oxygenase of TV. tabacum and Spinacia oleracea on the Oxygenase-Function of the Enzyme
Authors: Beuttenmüller M. , Nespoulous C. , Radunz A. , Schmid G. H.
Published: August 2018

In the present paper we demonstrate that the conformational state of the Afunctional enzyme ribulose-1,5-bisphosphate carboxylase oxygenase is different in the tobacco mulanl Susu when compared to the wild type tobacco or spinach. The conformational state of the tobacco mu- tant enzyme is characterized by the presence of a higher number of antigenic determinants ac- cessible to antibody binding. This seems to be correlated to a higher oxygenase activity in the mutant. The Afunctional enzyme ribulose-1,5-bisphosphate carboxylase oxygenase of the wild type tobacco Nicotiana tabacum var. John William’s Broadleaf, of the tobacco mutant Su.su and of spinach (Spinacia oleracea) was characterized by comparative immunological methods. Although the enzyme of the tobacco mutant appears identical to the enzyme of the wild type, when analyzed in immunodiffusion tests and immuno electrophoretical analyses, it exhibits a higher oxygenase activity. On the other hand the spinach enzyme exhibits only par- tial serological identity to the two tobacco enzymes. For the comparative studies pure IgG-fractions were prepared from the respective antisera. RuBP-carboxylasc oxygenase was used as a 70% purified enzyme preparation. Determination of the antibody binding capacity showed that the enzymes bind from the homologous antisera the highest amount of antibodies, which means that the antisera reflect the complementary picture of the enzyme structure. The enzyme molecules of N. tabacum var. JWB and of spinach bind 9 antibody molecules each. I lowevcr, the binding capacity of the tobacco mutant enzyme exhibiting the higher oxygenase activity is 30% higher. Measurement of the oxygenase function under the influence of the homologous as well as of the non-homologous antisera has led to the result that the oxygenase activity of all enzymes is inhibited. However, it is the degree of inhibition which differs. The antiserum to the mutant enzyme causes with the spinach as well as with the JWB-enzyme a higher degree of inhibition than that produced by the homologous antiserum. Therefore, a correlation between inhibitory effect brought about by this antiserum and the amount of antibodies bound does not exist. Whereas the enzyme of the tobacco wild type binds 20% less antibodies out of this antiserum its oxygenase activity is 60% more inhibited and the function of the spinach enzyme is 20% stronger inhibited although binding of antibodies from the antiserum to the tobacco enzyme is 50% lower. These observations permit the conclusion that the antiserum towards the mutant enzyme contains more antibodies with a higher binding affinity towards reactive regions of the oxy- genase function. This in turn means that the structure of this enzyme or its conformation must be different in comparison to the wild type enzyme.
Characterization of RuBP Carboxylase/Oxygenase of the N. tabacum Mutant Series "Consolation" with Homologous and Non-Homologous Antisera
Authors: Georgi S. , Radunz A. , Schmid G. H.
Published: August 2018

The molar ratio of RuBP carboxylase/oxygenase to the CF1 complex was determined in the wild type N. tabacum var. JWB and in various N. tabacum mutants, which differ with respect to their chloroplast structure and their photosynthetic and photorcspiratory activity. It appears that the ratio RuBP carboxylase oxygenase, CF1 is not constant in the different mutants, and apparently depends on the chloroplast structure and the photosynthetic capacity. In the green phenotypes of N. tabacum var. Consolation, var. NC 95 and var. Xanthi. whose lamellar system consists of a balanced ratio of grana and intcrgrana regions the ratio is 3-4 RuBP car- boxylase/oxygenase molecules per CF1 complex. In chloroplasts of the yellow-green mutant Su/su, and the yellow mutant of N. tabacum var. Consolation, whose lamellar system consists of extended intergrana regions and low stacked grana the RuBP carboxylase oxygcnasc/CF1 ratio is reduced to about one half. The aurea mutant A. tabacum Susu var. aurea and the yel- low-green leaf patches of variegated tabacum var. Xanthi arc characterized by the fact that one molecule RuBP carboxylase oxygenase correlates to two CF1 complexes. Also in the two N. tabacum mutants Su/su and Consolation green, that exhibit a 30% higher photorespiration these molar ratios depend on the chloroplast structure. The determination of the maximal binding of antibodies out of homologous and non-homo- logous antisera onto RuBP carboxylase oxygenase of the N. tabacum mutant Consolation showed, that the enzyme of the green mutant, which exhibits a higher oxygenase activity, has in comparison to the yellow-green and yellow phenotype of this mutant series and also in comparison to the wild type a 30 per cent higher antibody binding capacity. These differences in antibody binding arc shown in both the region of enzyme antibody equivalence and that of antibody excess. With the methods of enzyme-antibody precipitation in agarose gels these differences of enzymes, exhibiting higher or lower oxygenase activities, cannot be detected. The native enzymes and the large subunits of the enzyme of the three Consolation mutants yield in these test reactions with the enzyme of the wild-type fusing precipitation bands. Treatment with the chemical agent hydroxylamine. as well as heat treatment at 50 °C alters the enzyme conformation to such an extent that the antibody binding capacity is increased by 70%. The difference in the higher antibody binding capacity of the enzyme of the green mutant of N. tabacum var. Consolation is maintained also after these chemical modifications.