bluuebunny/crossref_metadata_2025_split huggingface dataset:
System Analysis of the Circadian Rhythm of Euglena gracilis, I. Linearities and Non-Linearities in the Response to Temperature Signals
Authors: Lork Wolfram , Kreuels Til , Martin Wolfgang , Brinkmann Klaus 
Published: August 2018

Abstract
The approach of control theory is used to describe the structure of the circadian system of Euglena gracilis. As a first step we discriminate linear and non linear properties of the dynamics.
The cellular motility as measured via long time records of sedimentation parameters in cultures is defined as the system output; sinusoidal temperature signals are used as input. By means of non stationary signal processing procedures we estimate gain and phase of the output signal. The problem of defining an appropiate gain of a cell suspension with an undefinite number of cells is solved by using the superimposition of two different input signals and by keeping one of them fixed as a reference signal.
Linear properties are shown with a linear frequency transfer and with the validity of the superposition principle at least within distinct regions of amplitude and frequency. Non linear properties are the signal distortion, the restriction of linear amplification to a distinct range of input temperature and the ambiguity of phase coupling near the circadian eigenfrequency.
The apparent lack of a limit of entrainment -an unexpected linear property - is explained by the masking effect of thermokinesis. A model is proposed describing the simultaneous control of motility by thermokinesis and the circadian system. On the base of that model further experiments are outlined.
Isolation of a b-Type Cytochrome Oxidase from Membranes of the Phototrophic Bacterium Rhodopseudomonas capsulata
Authors: Hüdig Hendrik , Drews Gerhart 
Published: August 2018

Abstract
A cytochrome oxidase (EC 1.9.3.1) was solubilized from the membrane fraction of aerobically grown cells of Rhodopseudomonas capsulata by treatment with Triton X-100. The enzyme was purified 160 fold by chromatography on DEAE-Sepharose CL-6B and affinity chromatography on cytochrome c-thiol activated Sepharose 4B.
The purified enzyme has a pH-optimum at 8.5 and a temperature optimum at 35 °C. The ap­ parent Km for reduced horse cytochrome c is 24 μм (at pH 8 and 30 °C). The purified cytochrome oxidase was 50% inhibited by 1.5 μм KCN and 10 μм NaN3. The purified enzyme contained one polypeptide of mr 65,000 and 6-type cytochrome.
Formation of Hydrocarbons by Photobleaching Cyanobacterium, A nacystis nidulans
Authors: Schmetterer Georg 
Published: August 2018

Abstract
The cyanobacterium Anacystis nidulans is bleached when subjected to both light and O2 to­ gether with suitable (pre)treatment o f the cells such as incubation at high (≧ 48 °C) or low (≦ 17 °C) temperatures, or in presence of metabolic inhibitors, or of substances forming com­ plexes with divalent cations. Concomitantly degradation o f the intracellular membranes is ob­ served (G. Schmetterer, G. A. Peschek, Biochem. Physiol. Pflanzen 176, 90-100 (1981)). The same three conditions cause formation of hydrocarbons, mostly ethane, a characteristic product of lipid peroxidation. Ethane production is unchanged and still light-sensitive even when no more pigments can be detected in the cells. In "white" cells light-dependent O2-uptake is also observed. The action spectrum of this process suggests that "completely" bleached cells retain very small amounts of residual chlorophyll, which must be unusually resistant to photooxidation.
Binding of Antibodies onto the Thylakoid Membrane VII. Localization of Coupling Factor of Photophosphorylation in the Lamellar System of Chloroplasts from Antirrhinum majus
Authors: Radunz Alfons , Meier Renate 
Published: August 2018

Abstract
The maximal binding of antibodies against the subunits of the coupling factor o f photo­ phosphorylation onto the ultrasonic sediment and to stroma-freed chloroplasts of Antirrhinum majus was determined. Different surfaces o f the thylakoid membrane are accessible to antibodies in both chloroplast preparations. Stroma-freed chloroplasts bind antibodies only at the outer surface, which is directed towards the stroma in intact chloroplasts. In the ultrasonic sediment, which is the product of ultrasonication and centrifugation, as was demonstrated by electronmicroscopy, the major part of the surface directed towards the inside of the thylakoids is accessible.
Both chloroplasts preparations are able to bind different amounts of antibodies to the five sub­ units of the coupling factor. While antigenic determinants of all five subunits are present on the surface directed to the outside, the δ-components seems to be lacking on the surface directed towards the inside. The α- and ε-component bind on both surfaces nearly the same amount of antibodies. Antigenic determinants of the β-subunit seem to exist in higher concentrations on the surface towards the outside and those of the γ-subunit on the surface towards the inside.
From the serological investigations it follows that coupling factor molecules span the thylakoid membrane from the outside to the inside. They are not only present in those parts of the thylakoid membrane, exposed in intact chloroplasts to the stroma, but also in stacked thylakoids. The differences between the results of other authors and the present results are discussed.
Use of Isolated Leaf Cells of A butilon theophrasti to Localize the Action of Two Aminotriazinone Herbicidal Derivatives
Authors: Hatzios Knton K. 
Published: August 2018

Abstract
The effects of the aminotriazinone herbicides metribuzin [4-amino-6-tert-butyl-3-(methylthio)-1,2,4,-triazin-5(4H)one] and metamitron [4-amino-3-methyl-6-phenyl-1,2,4-triazin-5(4H)-one] on the metabolism of enzymatically isolated leaf cells of Abutilon theophrasti Medic, were examined. Photosynthesis, protein, ribonucleic acid (RNA), and lipid synthesis were assayed by the in­ corporation of radioactive substrates such as NaH14CO3, [14C]leucine, [14C]uracil, and [14C]acetate, respectively, into the isolated cells. Photosynthesis was the most sensitive process inhibited by both herbicides, but metribuzin was a more potent inhibitor than metamitron. Protein synthesis was not affected by any herbicide. RNA synthesis was inhibited significantly by both herbicides and may be involved in their ultimate herbicidal action. Lipid synthesis was inhibited significantly only by the high concentrations of metribuzin, and it was not affected by any concentration of metamitron at any incubation time. Inhibition of lipid synthesis may be involved in the action of metribuzin as a herbicide.
Inhibition of Acetyl CoA Carboxylase by a High Molecular Weight Protein in Rat Liver
Authors: Abdel-Halim Mostafa N. , Yousufzai S. Y. K. 
Published: August 2018

Abstract
Acetyl CoA Carboxylase, Protein Inhibitor, Rat Liver A high molecular weight protein (approximately 1.5-2 × 106 daltons) has been found in rat liv­ er cytosol to inhibit acetyl CoA carboxylase activity. The protein inhibitor was purified by am­ monium sulfate precipitation, DEAE-cellulose chromatography and gel filtration. The inacti­ vation of the carboxylase is not attributable to either phosphorylation of the enzyme or to action on substrates or cofactors of the reaction. The activity of the inhibitor is destroyed by heating to 55 °C for 5 min, by treatment with trypsin, or by increasing bovine serum albumin in the reaction mixture. Hence it appears that the inhibitor is a regulatory protein that acts directly on acetyl CoA carboxylase.
Characterization of the Nuclear Lamina in an Insect by Differential Staining
Authors: Marx Ruth 
Published: August 2018

Abstract
The nuclear envelope of the larval fat body in the blow­ fly Calliphora vicina reveals a conspicuous nuclear lamina. It appears homogeneous, Fibrous or granular depending upon the fixing and staining methods. The best relative contrast for the nuclear lamina and the nuclear pore complex is obtained with a phosphotungstic acid staining procedure designed for proteins.
Versuche zur Synthese natürlich vorkommender prenylierter Naphthalinderivate. Nachweis eines neuen Prenylnaphthochinon- derivates in Galium mollugo / Synthesis of Naturally Occurring Prenylated Naphthalene Derivates. Isolation of a New Prenylnaphthoquinone from Galium mollugo
Authors: Heide Lutz , Leistner Eckhard 
Published: August 2018

Abstract
Several prenylated naphthalene derivatives were synthesized and characterized by spectroscopic methods. One of these compounds, 2-methoxycarbonyl-3-prenyl-1,4-naphthoquinone, was detected as a new natural product in the root system of Galium mollugo L. This new natural product is likely to be related to the biosynthesis of mollugin and anthraquinones.
Changes in the Fluorescence Emission Spectrum of Chlorella emersonii Induced by Cold Treatment; a Possible Regulative Feature of Energy Uptake
Authors: Harnischfeger G. , Jarry H. 
Published: August 2018

Abstract
Algae, when slowly cooled down to around -5 °C, undergo a change in the fluorescence emission spectrum subsequently taken at liqu. nitrogen temperature. This change resembles the magnesium effect described by Murata [BBA 189,171 - 181, (1969)] for isolated chloroplasts.
Evidence is shown, that both effects are indeed analogous. Cooling the organisms seems to in­ crease the permeability of the thylakoids for cations and, thus, a depletion with concomitant changes in membrane structure. The system serves as a model for the probable in vivo control of pigment interaction through alteration of membrane properties.
A Study of State Changes in Chlorella: The Effect of Uncoupler and Energy Transfer Inhibitors
Authors: Sane P. V. , Furtado D. , Desai T. S. , Tatake V. G. 
Published: August 2018

Abstract
Pre-illumination of Chlorella cells at room temperature with light primarily absorbed by PSII (650 nm) produces a state called state II. This is characterized by high fluorescence at 715 nm (high F715/F685) at liquid nitrogen temperature. Alternately if the cells are pre-illuminated by light primarily absorbed by PSI (710 nm) then state I with high fluorescence at 685 nm (low F715/ F685) at 77K is produced. We have investigated the role of photophosphorylation in the development of state I/II in chlorella cells using uncoupler and energy transfer inhibitors. The results suggested that the development of state I depends upon the energization of the membrane. Both DCCD and TPTC which permit build up of proton gradient block the adaptation to state I in­ dicating that proton gradient formation alone is not sufficient to develop state I. The data obtain­ ed by us as also published in the literature indicate that redox states o f the electron transport carriers are responsible for the development of state II.
Ca Entry and Contraction as Studied in Isolated Bovine Ventricular Myocytes
Authors: Isenberg Gerrit 
Published: August 2018

Abstract
Single bovine ventricular myocytes were superfused with Tyrode solution containing 1.8 mᴍ CaCl2. The cells did not bear external load and contracted isotonically. Contraction and relaxation were characterized by the shortening and relengthening of the sarcomeres which resembled in their time course the isometric twitches of bovine papillary muscles. Resemblance was also found in regard to positive inotropic interventions as increase in the stimulation frequency, exposure to elevated [Ca]0 or to adrenaline.
A two-microelectrode voltage-clamp technique was applied to the single myocyte. The trans­membrane Ca inward current ICa was defined as difference current sensitive to 5 mᴍ Ni or to 2 μᴍ D600. During a voltage step from -45 to + 5 mV, ICa peaked within 3 ms to -6 nA, afterwards it decayed to 15% of peak amplitude (incomplete inactivation with a 2 exponential time course). Experiments in Na-free media suggested that Na entry does not significantly contaminate ICa. Therefore, Ca entry could be calculated from ICa. The increment in total intra­ cellular Ca concentration (Δ[Ca]i
T) was estimated by referring Ca entry to the cell volume (50 pl).
Within 100 ms Δ[Ca]i
T came to 25 μᴍ at control conditions, to 55 μᴍ at [Ca]0 = 3.6 mᴍ and to 88 μᴍ when 0.1 μᴍ adrenaline were present. The Δ[Ca]i
T values were sufficient to activate contraction without the necessity of Ca-release from SR.
Despite the new data, the relationship between Ca entry and activation of contraction was complex: during the “positive Herztreppe” ICa slightly attenuated but contractility doubled. Therefore, the old EC-model (M. Morad and Y. Goldman, Progr. Biophys. Mol. Biol. 27, 257 (1973)) was adapted. The Ca-entry’s capability to load and to overload the intracellular Ca store (SR) is discussed.
Notizen: Synthesis of 6-Chlorogenistein
Authors: Lévai Albert , Tökés Adrienne L. 
Published: August 2018

Abstract
Chlorochalcone, Chloroisoflavone, Oxidation with Thallium(III) Nitrate An unambiguous synthesis of 6-chlorogenistein (5,7,4′-trihydroxy-6-chloroisoflavone) has been worked out via the oxidation of 2′-hydroxy-4,4′,6′-trimethoxy-5′-chlorochal-cone with thallium(III) nitrate followed by the demethylation of the 5,7,4′-trimethoxy-6-chloroisoflavone.
High-and Low-Affinity Binding of Photosystem II Herbicides to Isolated Thylakoid Membranes and Intact Algal Cells
Authors: Laasch Henrik , Pfister Klaus , Urbach Wolfgang 
Published: August 2018

Abstract
High- and low-affinity binding of photosystem II herbicides to isolated thylakoids of Spinacia oleracea and to intact cells of the unicellular green alga Ankistrodesmus braunii were investigated.
Complete mutual displacement of bound diuron-type herbicides (e.g. diuron, atrazine, terbutryn) by either diuron- or phenol-type herbicides (e.g. ioxynil, dinoseb) in thylakoids as well as in intact algal cells was found for herbicide concentrations (< 4 nmol bound herbicide/mg Chl) which gave almost saturated high-affinity binding. This demonstrates a high degree of specific binding of these herbicides towards their receptor sites even in intact algal cells. In contrast, phenol-type herbicides are largely unspecifically bound in algal cells.
The mechanism of binding of all photosystem II herbicides at the high-affinity (specific) binding site was found to be competitive. Within the group of diuron-type and of phenol-type herbicides as well as between these two groups, graphical and quantitative analysis of the Lineweaver- Burk plot and of the Dixon plot indicated competitive binding. From this a common binding site for both types of herbicides was concluded. The involvement of two different herbicide binding- proteins is discussed. Low-affinity (unspecific) binding was found to be irreversible in contrast to the easily reversible high-affinity binding. Irreversibility was indicated by a lack of displacement. It is proposed that low-affinity binding represents either a partitioning of the herbicides into the lipophilic parts of the membranes or an attachment to distinct receptor sites. Unspecifically bound herbicides might be responsible for several high concentration effects of the photosystem II herbicides, which are described in the literature. Evidences for the possible existence of a second binding site of these herbicides are presented.
A Cyanobacterial ATPase Distinct from the Coupling Factor of Photophosphorylation
Authors: Lockau Wolfgang , Pfeffer Susanne 
Published: August 2018

Abstract
A particle-bound, Mg2+ -dependent ATPase activity is investigated in cell-free extracts of the tyanobacterium Anabaena variabilis. The enzyme can be clearly distinguished from the cyanobacterial coupling factor of photophosphorylation and from the alkaline phosphatase. It requires low concentrations of Ca2+ for maximal activity and is inhibited by ortho-vanadate, indicating that the enzyme may form a phosphorylated intermediate in its catalytic cycle. The distribution of the ATPase in sucrose density gradients does not follow that of thylakoids. It is concluded from these characteristics that the enzyme is bound to the plasma membrane. The cytochrome oxidase activity of the extracts appears to be restricted to the thylakoids.
Sodium-Potassium Movement and the Regulation of Cardiac Muscle Activity
Authors: Daut Jürgen , Rüdel Reinhardt 
Published: August 2018

Abstract
The changes in intracellular sodium activity and contractility produced by short-lasting application of a fast-acting cardiac glycoside were measured in guinea-pig ventricular muscle. It was found that under certain conditions the change in twitch tension paralleled the change in sodium activity. It is suggested that the electrogenic sodium pump may be involved in the regulation of both the mechanical and the electrical activity of cardiac muscle.
The Intensity Dependence of the Receptor Potential of the Limulus Ventral Nerve Photoreceptor in Two Defined States of Light-and Dark Adaptation
Authors: Stieve H. , Bruns M. , Gaube H. 
Published: August 2018

Receptor potentials of Limulus ventral nerve photoreceptors were evoked in reproducible states of moderate light- and considerable dark adaptation (LA, DA) with light stimulus intensities from threshold to saturation values using a repeated flash sequence.
With increasing light intensities latent period and time-to-peak shortened in the state of both LA and DA The decrease-time is prolonged by increasing stimulus intensities (LA and DA) and continues to rise even when the amplitude of the receptor potential is already saturated.
The sigmoid response height vs. log stimulus intensity curve is shifted upon LA towards higher stimulus intensities, and its steepness is increased. LA prolongs latent period and time-to-peak at low light intensities; at high light intensities, however, the DA-values are longer. The decreasetime of the receptor potential is always shorter in the light-adapted state.
The results are discussed according to the assumption that size and duration of the receptor potential are primarily determined by the distribution of bum p latencies. Changes of the receptor potential parameters are explained by changes of bum p size and of bum p latency distribution due to light adaptation.
On a Quantitative Determination of Antibodies to Lipids and Proteins
Authors: Radunz A. 
Published: August 2018

The amount of precipitating antibodies in monospecific lipid- and protein antisera was determined by quantitative precipitation reactions according to the methods of Heidelberger and Kendall. Antisera were obtained by immunization of rabbits. Fragments of the thylakoid membrane from Antirrhinum chloroplasts were used as antigens for the binding of antibodies. These fragments had a diameter of 100 Å. They were composed of 51% proteins and 39% lipids.
It was found that antisera to the lipids mono-, tri- and digalactosyl diglyceride, sulfoquinovosyl diglyceride and phosphatidyl glycerol contained 20 to 92 μg precipitating antibodies per ml serum. In antisera to the coupling factor of photophosphorylation, cytochrome f, a polypeptide with the apparent MW 24000 and a serum to the total protein of the lam ellar system 23 to 99 (ig were found. In chloroplast antisera the amount of all precipitating lipid- and protein antibodies amounted to 765 μg per ml. The described antisera originated from blood that had been withdrawn from the test animals 4 to 10 week after antigen injection
Separation, Purification, and Characterization of Two Isoforms of Glutamine Synthetase from Chlamydomonas reinhardii
Authors: Florencio Francisco J. , Vega José M. 
Published: August 2018

Two isoforms of glutamine synthetase. GS1 and GS2, have been separated from Chlamydomonas reinhardii cells grown autotrophically with nitrate. The intracellular level of GS2 was higher than that of GS1. In cells under darkness, the GS1 peak increased markedly, whereas that of GS2 became negligible.
The two isoenzymes were purified to electrophoretic homogeneity by a method which included: a) DE-52 cellulose chromatography; b) ammonium sulphate fractionation: and c) affinity chromatography on ADP-sepharose. The specific activity was 114 and 63 U/mg for GS1 and GS2 respectively, and both enzymes (Mr = 380 000 and 373 000) are oligomeric proteins composed by 8 subunits of similar size (Mr = 48 000 in GS1, and 46 000 in GS2). The basic differences between GS1 and GS2 are: a) the effect of light on their intracellular level: b) their Km for ammonium (83 and 244 μᴍ, respectively). Both isoenzymes were inhibited in a similar extent by ʟ-alanine, ʟ-glycine and ʟ-arginine.
Variable Fluorescence and Fluorescence Spectra of Algae after Herbicide-Induced Pigment Bleaching
Authors: Karapetyan Navassard V. , Strasser Reto , Boger Peter 
Published: August 2018

Herbicides like norflurazon, oxadiazon, or oxyfluorfen affect the pigment apparatus of green algae. Their influence on variable (FmaK - F0) and initial fluorescence (F0) as well as on the state of chlorophylls were investigated. Two main modes of action of these herbicides on the photo­synthetic apparatus during growth have been found:
First: Scenedesmus cells grown with norflurazon. a carotene-biosynthesis inhibitor, show chlorophyll bleaching concurrently with decrease or inactivation of photosystem-II reaction centers, with small changes in fluorescence spectra. Further, electron transport is blocked at the acceptor side of photosystem II. Disappearance or inactivation of photosystem-II reaction centers after a 50% loss of chlorophyll is accompanied by a sharp increase of the F0 yield, with small changes in the chlorophyll state. The slow-decay phase in fluorescence induction of these cells, enhanced by dithionite, is ascribed to a reversible photobleaching of chlorophyll during the measurement.
Second: Oxadiazon and oxyfluorfen alter substantially the state of chlorophylls and cause strong bleaching, but reaction centers of photosystem II, although less than in control cells, are active even after an 80% disappearance of chlorophyll. The yields of F0 and (Fmax - F0) in treated cells are independent of the extent of chlorophyll bleaching. In contrast to norflurazon, the latter two herbicides do not inhibit carotenogenesis. Decrease of photosystem-II reaction centers may be due to non-specific pigment destruction (oxyfluorfen) or interference w'ith chlorophyll biosynthesis.
Cyclic AMP Is Not Involved as a Second Messenger in the Response of Soybean to Infection by Phytophthora megasperma f. sp. glycinea
Authors: Hahn Michael G. , Grisebach Hans 
Published: August 2018

Abstract
cAMP levels were monitored in soybean (Glycine max) infected with race 1 of Phytophthora megasperma f. sp. glycinea and in soybean cell suspension cultures treated with a glucan elicitor from P. megasperma. While cAMP could be readily detected in soybean hypocotyls using a radio ­ immunoassay, no correlation was observed between infection and cAMP levels. No cAMP was detected in suspension cultured soybean cells. These results suggest that cAMP does not play a significant role in the plant's response to fungal attack, or the response of suspension cultured cells to elicitor.