bluuebunny/crossref_metadata_2025 huggingface dataset:
Phosphorylase Phosphatase Activity in Saccharomyces cerevisiae 257
Authors: Christova Nelly , Galabova Danka
Published: August 2018

Phosphorylase Phosphatase, Protein Phosphatase, Saccharomyces cerevisiae Aphosphatase, active towards phosphorylase a and phosphorylated proteins casein and histone II-A , was isolated from Saccharomyces cerevisiae 257. The enzyme dephosphorylated glycogen phosphorylase from commercial yeast rendering it inactive. The protein phosphatase activity was not influenced by any metal ions. Phosphorylase phosphatase activity was slightly stimulated by p -nitrophenyl phosphate and inhibited by heparin.
Determination of C/N Ratios Required for De-Repression of Nitrogenase in Rhodobacter capsulatus
Authors: Dörffler Michael , Steindorf Astrid , Oelze Jürgen
Published: August 2018

Phototrophic continuous and batch cultures of Rhodobacter capsulatus were employed to identify the C/N ratio above which nitrogenase is de-repressed. The cultures were grown with limiting amounts of ammonium as source of bound nitrogen and with ʟ-lactate or ʟ-malate as sources of carbon and reducing equivalents. De-repression of nitrogenase was determined on the basis of the occurrence of dinitrogen fixation, acetylene reduction and nifH promoter activities as well as on the basis of hydrogen evolution and nitrogenase poly­ peptides. In continuous culture, cells started to fix dinitrogen, to reduce acetylene, to activate the nifH promoter and to form nitrogenase polypeptides, when consuming lactate per ammonium at a C/N ratio of about 6 (this ratio represents the number of C and N atoms consumed). With malate as carbon source all of the activities becam e detectable above a C/N ratio of about 8. Essentially the same C/N ratios were determined with batch cultures for the occurrence of N -limitation of growth and hydrogen evolution. The experimentally deter­mined C/N ratios for nitrogenase de-repression essentially agreed with C/N ratio of 5.8 and 7.8 calculated for the assimilation of ammonium and either lactate or malate, into biomass of an elemental com position of CH1.83N0.183O0.5-This means that the occurrence of N -limitation and nitrogenase de-repression is defined by a threshold C/N ratio required for biomass production. As experimentally and theoretically shown, this ratio depends on the reduction state of the carbon source. It is concluded that the C/N ratio of nutrient consumption represents an intracellular signal which is directly translated into nitrogenase de-repression.
Interference by Nickel(II) Salts and Their 5-Methylimidazole-4-carboxylate Coordination Compounds on the Chloroplast Redox Chain
Authors: King-Díaz Beatriz , Barba-Behrens Nórah , Montes-Ayala Josefina , Castillo-Blum Silvia E. , Escartín-Guzmán Concepción , Iglesias-Prieto Roberto , Lotina-Hennsen Blas
Published: August 2018

Nickel(II) salts and their coordination com pounds with ethyl 5-m ethylim idazole-4-carboxylate (emizco), [Ni(emizco)2Cl2], [Ni(emizco)2Br2], [Ni(emizco)2(H2O)2] (NO3)2 H2O · Ni(NO3)2, inhibit photosynthetic electron flow (basal, phosphorylating and uncoupled) and ATP-synthesis, therefore behave as Hill reaction inhibitors. Coordination compounds are more potent inhibitors than the salts. It was found that the target for NiCl2; NiBr2 and Ni(NO3)2 is at the b6f level. On the other hand, the complexes [Ni(Emizco)2Cl2], [Ni(Emizco)2Br2] and [Ni(emizco)2(H2O )2] (NO3)2H2O binding sites are located at QB(D1)-protein and b6f level. Therefore, they have a common inhibition site located at b6f avoiding the PQH2 oxidation. The QB inhibition site was corroborated by variable chlorophyll a fluorescence yield [V(j)]. The emizco ligand has no activity on photosynthetic electron flow.
Correlation between Virulence of Various Strains of Mycobacteria and Their Susceptibility to Ethanolic Extract of Propolis (EEP)
Authors: Scheller Stan , Kawalski Henryk , Oklek Kazimierz , Dworniczak Szymon , Matsuno Tetsuya , Waldemar-Klimmek Krystian , Rajca Marek , Shani ashovam
Published: August 2018

extract of propolis (EEP) has antibacterial, antiviral, antiprotozoal and antifungal properties, in addition to many biological effects. Our laboratory has demonstrated a syner­gistic effect of EEP and antibiotics on the growth of Staphylococcus aureus, and suggested that the bactericidal effect of EEP was expressed mainly on virulent mycobacteria rather than on non-virulent (attenuated) ones. The present study was designed to reconfirm the latter finding, by subjecting 17 different mycobacteria strains to EEP, and evaluating whether there is a correlation between the virulence of the mycobacteria strains studied and their susceptibility to EEP. Our findings demonstrate that while the four non-virulent strains studied are not susceptible to EEP, out of the 13 virulent strains studied seven are susceptible and six are resistant to it. These results suggest that while there is no full correlation between virulence of the mycobacteria tested and their susceptibility to EEP, the few strains that were resistant to EE P were non-virulent.
Superoxide-Dependent and -Independent Nitrite Formation from Hydroxylamine: Inhibition by Plant Extracts
Authors: Rohnert Ute , Schneider Werner , Elstner Erich F.
Published: August 2018

Reactive oxygen species such as OH·, peroxynitrite and the non-radical, hypochlorous acid, play outstanding roles in many diseases. The formation of OH·(Fenton-)-type radicals is catalyzed by enzymes such as xanthine oxidase (XOD) via one-electron reduction of mo­lecular oxygen producing superoxide radical anions (O2·-). Subsequent transfer of one elec­ tron to hydrogen peroxide by Fe2+ or Cu+-ions yields OH-radicals measurable as ethene release from 1-keto-4 methylthiobutyrate (KMB). Xanthine oxidase or activated neutrophils are prominent sources of this strong oxidant produced at inflammatory sites. Many natural compounds such as salicylates or flavonoids interfere either with the pro­ duction of these activated oxygen species or function as radical scavengers and thus as antiox­ idants. Extracts from willow-bark (Salix spec.) and also other species such as ash-tree (Fraxi-nus spec.) or poplar (Populus spec.) have been used as antiinflammatory drugs since a long time. In this communication we wish to report on model reactions to demonstrate a) the radical scavenging activities of such plant extracts inhibiting ethene release from KMB induced by Fenton-type oxidants and b) the inhibition of the formation of nitrogen monoxide (NO) from hydroxylamine includ­ing XOD either in the presence or absence of myoglobin (MYO) measurable as nitrite forma­tion: In the absence of MYO, superoxide dismutase is an excellent inhibitor of nitrite forma­tion but is inactive in its presence. Extracts from the willow-bark or the drug PhytodolorR, however, are inhibitory both in the presence and absence of MYO. As active principle, the flavonoid rutin included in these extracts is likely to function as one inhibitor of the XOD-mediated reaction.
The Exogenous NADH Dehydrogenase of Heart Mitochondria Is the Key Enzyme Responsible for Selective Cardiotoxicity of Anthracyclines
Authors: Nohl H. , Gille L. , Staniek K.
Published: August 2018

The molecular mechanism of the anthracycline-dependent development of cardiotoxicity is still far from being clear. However, it is generally accepted, that mitochondria play a significant role in triggering this organ specific injury. The results presented in this study demonstrate that, in contrast to liver mitochondria, isolated heart mitochondria shuttle single electrons to adriamycin, giving rise to oxygen radical formation via autoxidation of adria­mycin semiquinones. This one electron reduction of anthracyclines is catalyzed by the exoge­nous NADH dehydrogenase associated with complex I of heart mitochondria, an enzyme which is lacking in liver mitochondria. Upon addition of NADH heart mitochondria generate significant amounts of adriamycin sem iquinones while liver mitochondria were ineffective. Adriamycin semiquinones undergo both autoxidation leading to superoxide radical release and complex reactions under formation of adriamycin aglycone. Due to the high lipophilicity adriamycin aglycones accumulate in the inner mitochondrial membrane where they interfere with electron carriers of the respiratory chain. Adriamycin aglycone sem iquinones emerging from an interaction with complex I were found to trigger homolytic cleavage of H2O2 which results in the formation of hydroxyl radicals. As demonstrated in this study the activation of adriamycin by the exogenous NADH dehydrogenase of cardiac mitochondria initiates a cas­cade of reaction steps leading to the establishment of oxidative stress. Our experiments sug­ gest the exogenous NADH dehydrogenase of heart mitochondria to play a key role in the cardiotoxicity of adriamycin. This organ-specific enzyme initiates a sequence of one electron transfer reactions ending up in the establishment of oxidative stress.
Production of Antibiotics by Collybia nivalis, Omphalotus olearius, a Favolaschia and a Pterula Species on Natural Substrates
Authors: Engler Michaela , Anke Timm , Sterner Olov
Published: August 2018

Collybia nivalis, Favolaschia sp. 87129, Pterula sp. 82168 and Omphalotus olearius were cultivated on natural substrates. The antibiotic metabolites oudemansin A, strobilurins A, D. illudin S and pterulone were isolated and identified. A new antifungal metabolite, pterulone B, was described from cultures of Pterula sp. 82168 on wood. Collybia nivalis was found to be the first species of this genus to produce strobilurins and oudemansin A. As compared to rich media the cultivation on natural substrates resulted in the production of fewer metabolites. The concentrations of the antibiotics, however, were sufficient to inhibit other saprophytic fungi.
Yeast Permeabilization as a Tool for Measurment of in situ Enzyme Activity: Localization of Alkaline Phosphatase
Authors: Spasova D. , Galabova D.
Published: August 2018

The biochemical and ultracytochemieal localization of alkaline phosphatases in permeabilized cells of Saccharomyces cerevisiae 257 has been studied. The treatment with non-ionic surfactant Triton X-100 allows the penetration of the substrate into intact yeast cells and thus provides detailed detection of the enzyme activity in ultracytochemical studies.
Nuclear Translocation of Tissue Type Transglutaminase during Sphingosine-Induced Cell Death: A Novel Aspect of the Enzyme with DNA Hydrolytic Activity
Authors: Takeuchi Yutaka , Ohashi Hiroshi , Birckbichler Paul J. , Ikejim Takashi
Published: August 2018

Tissue type (type 2) transglutaminase (TGase, EC 2.3.2.13) has been implicated in various cellular processes including cell death. In order to better understand the role of this enzyme in cell death, human melanocytic A375-S2 cells were treated with sphingosine, a cell-signaling mediator. During the rapid onset of cytotoxicity caused by this lipidic agent, tissue TGase was translocated from the cytoplasm to the cell nuclei. This observation was further remarked in relevance to its previously undescribed activity for DNA degradation. The DNA hydrolytic activity associated with tissue TGase was dependent on Mg2+ in contrast to the Ca2+ requirement for the classical cross-linking acrivity of TGase, and was inhibited by Zn2+. Based on the results shown here, we propose a novel aspect of tissue TGase in cell death.
A New Bromotyrosine Alkaloid from the Caribbean Sponge Aiolochroia crassa
Authors: Assmann Michael , Wray Victor , van Soest Rob W. M. , Proksch Peter
Published: August 2018

A detailed analysis of the chemical constituents of a Caribbean specimen of Aiolochroia crassa was performed. Five brominated products (1 -5) were isolated and one of these was a new bromotyrosine metabolite. The structure of the new compound 1 has been established from spectral studies. Compounds 1 and 2, which are the major brominated metabolites and have not been previously identified in any Aiolochroia species, could be usefully employed as chemotaxonomic markers.
Constituents of Brazilian Geopropolis
Authors: Bankova V. , Christov R. , Marcucci C. , Popov S.
Published: August 2018

Three samples of Brazilian geopropolis, collected by three indigenous bee species, were investigated by GC/MS. More than 50 compounds were identified, mainly terpenoids and phenolics. The chemical composition of propolis gathered by different bee species was different.
Choline Acetyltransferase from the Electric Organ of Electrophorus electricus (L.) – Physicochemical Characterization and Immunochemical Identification
Authors: Tavares N. Nunes , Hassón-Voloch A.
Published: August 2018

Acetylcholine Biosynthesis, Choline Acetyltransferase, Electrophorus electricus (L.), Electrocytes It is well known that the regulation of choline acetyltransferase (ChAT) activity, under physiological conditions, is important for the development and neuronal activities of cholinergic systems. The purification of ChAT has been obtained from many sources such as electric organs of fishes, Drosophila melonogaster, and mammals. We have prepared choline acetyl-transferase from a pool of supernatants obtained by differential centrifugation of electric organ homogenates from Electrophorus electricus (L.) in Tris-phosphate buffer, 0.05 m , pH 7.6. The first step of the enzyme purification was performed by ammonium sulfate precipitation at 40% and 80% . The precipitate at 80% was solubilized with sodium-phosphate buffer 0.05м , pH 7.6, dialyzed, chromatographed on DEAE-52 column and the active fraction submitted to FPLC system columns (Mono-Q: ion exchange -Superose-12: gel filtration). ChAT activity from the eluates was estimated by Fonnun’s method [Fonnun, 1975], with Acetyl-Coenzyme A tritium labelled ([3H ]AcCoA) as substrate, and the synthesis of 3HACh formed was measured. The peak from gel filtration showed a relative molecular mass of 80 kDa with highest activity in the order of 77,42 nmoles ACh/min/mg protein. This fraction was analyzed by SDS-PAGE and a band of 42 kDa was detected with Coomassie blue stain, indicating that the enzyme is formed by two subunits. Employing an antibody, the presence of ChAT was confirmed with the Western blotting technique. Isoelectrofocusing analysis demonstrated two isoforms with pI of 6,49 and 6,56, respectively.
An Architecture for Distributed Visual Memory
Authors: Jungclaus Nils , Heyde Markus von der , Ritter Helge , Sagerer Gerhard
Published: August 2018

The development of autonomous as well as situated robots is one of the great remaining challenges and involves a number of different scientific disciplines. In spite of recent dramatic progress, it remains worthwhile to examine natural systems, because their abilities are still out of reach. Motivated by research work done in the fields of cognitive systems, visual perception, and psychology of memory we designed and implemented a memory architecture for visual tasks. Structural and functional concepts of the memory architecture were modeled on the ones found in natural systems. We present an efficient implementation based on parallel programming techniques.

The memory module is integrated into a distributed system for speech and image analysis, which is currently developed in the Sonderforschungsbereich (SFB) 360, Situated Artificial Communicators, where a hybrid vision system combining neural and semantic networks is used.
How Can Adaptive Behavioural Plasticity Be Implemented in the Mammalian Brain?
Authors: Koch Michael
Published: August 2018

The adaptive control of behaviour requires brain mechanisms for the selection (i.e. activa­tion and suppression) of responses, as well as mechanisms for the modulation of the response vigour. The concept of motivation postulates the existence of brain centres that regulate the selection and strength of behavioural responses. The present paper provides examples from the behavioural neurosciences for brain mechanisms that lead to adaptive changes of an organisms responsiveness to external stimuli. The mammalian startle response is a simple defensive behaviour which is mediated by an oligosynaptic pathway located in the lower brainstem. The startle response is enhanced by aversive states (fear, anxiety) and attenuated by appetitive states (pleasure), which can be regarded as an example of motivational priming. Furthermore, the startle response is inhibited by a weak sensory stimulus presented shortly before the startling stimulus. The suppression of startle by a prepulse is an example of sen­ sorimotor gating, a principle that is important for the hierarchical organisation of behaviour. This paper describes the neuronal mechanisms underlying the modulation (prepulse inhibi­tion and fear potentiation) of the startle response in rats, and discusses the possible adaptive significance of these different phenomena of behavioural plasticity.
Simulation of Complex Movements Using Artificial Neural Networks
Authors: Cruse Hoik , Dean Jeffrey , Kindermann Thomas , Schmitz Josef , Schumm Michael
Published: August 2018

A simulated network for controlling a six-legged, insect-like walking system is proposed. The network contains internal recurrent connections, but important recurrent connections utilize the loop through the environment. This approach leads to a subnet for controlling the three joints of a leg during its swing which is arguably the simplest possible solution. The task for the stance subnet appears more difficult because the movements of a larger and varying number of joints (9 -18: three for each leg in stance) have to be controlled such that each leg contributes efficiently to support and propulsion and legs do not work at cross purposes. Already inherently non-linear, this task is further complicated by four factors: 1) the combination of legs in stance varies continuously, 2) during curve walking, legs must move at different speeds, 3) on compliant substrates, the speed of the individual leg may vary unpredictably, and 4) the geometry of the system may vary through growth and injury or due to non-rigid suspension of the joints. This task appears to require some kind of “motor intelligence”. We show that an extremely decentralized, simple controller, based on a combi­nation of negative and positive feedback at the joint level, copes with all these problems by exploiting the physical properties of the system.
Non-Linear Mechanisms in the Brain
Authors: Mayer-Kress Gottfried
Published: August 2018

Non-linear dynamical models of brain activity can describe the spontaneous emergence of large-scale coherent structures both in a temporal and spatial domain. We discuss a number of discrete time dynamical neuron models that illustrate some of the mechanisms involved. Of special interest is the phenomenon of spatio-temporal stochastic resonance in which co­herent structures emerge as a result of the interaction of the neuronal system with external noise at a given level punitive data. We then discuss the general role of stochastic noise in brain dynamics and how similar concepts can be studied in the context of networks of con­nected brains on the Internet.
Occurrence of 2,4-Dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA) and a β-Glucosidase Specific for Its Glucoside in Maize Seedlings
Authors: Ebisui Kenkichi , Ishihara Atsushi , Hirai Nobuhiro , Iwamura Hajime
Published: August 2018

2,4-Dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA) and its glucoside, DIMBOA - G, appeared concurrently with germination in maize (Zea mays L.), and their concentrations per fresh weight reached a maximum 24-36 hr after germination. The aglycone then decreased to disappear as the plants began autotrophic growth, and the glucoside to a concentration half that of the maximum. The level of DIMBOA-G was always higher than that of the aglycone. A β-glucosidase activity which hydrolyzes DIMBOA-G to DIMBOA and glucose was detected in crude enzyme extracts from the seedlings. Its activity per fresh weight varied concurrently with the occurrence of DIMBOA. The purification was performed to an apparent homogeneity by cryoprecipitation followed by cation exchange chromatography and gel filtration. The Km value for DIMBOA-G was 0.07 mᴍ, whereas that for DIBOA-G, that was substantially absent in the seedlings of the cultivar studied, was 0.52 mᴍ. The activity on salicin and esculin was too low to be detected. The set of results suggested that free DIMBOA occurs constitutively or in a programmed manner as defense compound at a seedling stage of growth, and a specific glucosidase is involved in this process.
Phytohormone-Mediated Induction of Red Colour in the Flower Florets of a Cultivar of Dyer’s Saffron (Carthamus tinctorius)
Authors: Saito Koshi , Miyakawa Ken-Ichi , Murata Takayuki , Enomoto Yuji
Published: August 2018

Gibberellic acid was fed to a homogenate of Mogami-Benibana, a cultivar of dyer’s saffron (Carthamus tinctorius), at a 100 μᴍ level. After incubation for 60 min at 25 or 37 °C, the effect of externally supplied gibberellic acid on enzyme activities and the glucose level were investigated. Gibberellic acid enhances the activity of glucose oxidase by about 52%. It induces also a weak (9%) increase of glucosidase activity. Gibberellic acid increases the glucose content by about 6% during the initial 30-min incubation. The results relate to the red colour appearance in Mogami-Benibana at the later stage of blooming.
Differential Changes in the Photosynthetic Pigments and Polyamine Content during Photoadaptation and Photoinhibition in the Unicellular Green Alga Scenedesmus obliquus
Authors: Kotzabasis Kiriakos , Dörnem Dieter
Published: August 2018

In the unicellular green alga Scenedesmus obliquus the level of photoinhibition and the recovery of the cells after reversal to the initial light conditions in relation to the pre-photoadaptation of the culture to low, medium and high light intensity was determined. The changes in the photosynthetic pigment content and in the intracellular polyamine concentration allowed to distinguish between photoadaptation and photoinhibition. In particular, the level of chlorophylls, xanthophylls and carotenoids decreased inversely proportional to the light intensity applied during photoadaptation, whereas their concentrations remained constant during photoinhibition. The violaxanthin/zeaxanthin and the loroxanthin/lutein cycle work only under photoinhibitory conditions, but not under photoadaptive premises. Changes in the level of these carotenoids in relation to the changes in the photosynthetic apparatus during photoadaptation are discussed. In addition, it was found that the intracellular polyamine level increased only under stress conditions, i. e. during photoinhibition, and decreased during recovery of the cells after reversal to the initial light conditions. The increase of the putrescine level during photoinhibition is inversely proportional to the light intensity used for pre-adaptation. This rise of the polyamine level in the cells photoadapted to high light conditions is an additional indication for the finding that photoadaptation and photoinhibition are different phenomena which are clearly distinguishable from each other. Finally, the changes of the chlorophyll, violaxanthin, zeaxanthin, loroxanthin, lutein and polyamine levels under photoadaptation in high light intensity (50 W m -2) in relation to the range of photoadaptation in Scenedesmus obliquus are discussed.
Peroxidase-Like Activity of Catalase Immobilized on Carbon Materials
Authors: Horozova E. , Dimcheva N. , Jordanova Z.
Published: August 2018

The immobilization of catalase was carried out from enzyme solutions in acid (pH < 3.5) and alkaline (pH > 11) medium on two kinds of soot differing by the average size of the particles. Under these conditions the peroxidase-like activity of immobilized catalase in the oxidation of phenol has been studied. The effect of the initial concentration of the substrate on the rate of the process catalysed by catalase immobilized on the soot of finer-grained structure has been studied. The relationships obtained are described by the equation of Michaelis- Menten. The kinetic parameters (the constant of Michaelis - Km, the maximum reaction rate - Vmax, the rate constant - k and the activation energy - Ea) of the process were calculated. It was found that catalase absorbed on the soot of larger globular particles does not take part in the peroxidase oxidation of phenol.
Citronellol and Citronellyl Esters from the Paracloacal Glands of the Broad-Snouted Caiman, Caiman latirostris (Crocodylia, Reptilia)
Authors: McDaniel C. J. , Dunn B. J. , Weldon P. J.
Published: August 2018

The secretions of the paracloacal glands of an adult male broad-snouted caiman (Caiman latirostris) were analyzed by GC/MS. 3,7-Dimethyl-6-octen-1-ol (citronellol) and four citronellyl esters, with acid moieties ranging from two to five carbons, were identified. Squalene, β-farnesene, and straight-chain esters also were observed.
Magnetoliposomes May Be Useful for Elimination of HIV from Infected Individuals
Authors: Babincová Melánia , Eva Machová Eva
Published: August 2018

A simple method is proposed for the treatm ent of the acquired immunodeficiency syndrome (AIDS) by introducing into the blood stream magnetoliposomes with coupled human immunodeficiency virus (HIV) receptor proteins. After some time lag, needed for binding of HIV and HIV-infected cells to magnetoliposomes, the arterio-venous shunt, as used with dialysis patients should be inserted and the patient’s blood should be passed through multiple tubes filled with stainless steel wool, each of which is surrounded by a coil producing a strong non-homogeneous magnetic field, which may result in a substantial reduction of HIV and HIV-infected cells in the infected body.
Rosa Taxonomy and Hierarchy of Markers Defined by ACT STATIS
Authors: Grossi C. , Raymond O. , Sanlaville-Boisson C. , Jay M.
Published: August 2018

The ACT STATIS method, a multi-table comparison, was applied to 62 Rosa species to be clustered into four sections (Carolinae, Cinnamomeae, Pimpinellifoliae and Synstylae); the data sets were dealing with morphology (15 criteria), anthocyanin pattern (10 compounds), flavonol heteroside pattern (26 compounds) and superoxide dismutase isozyme (SOD) polymorphism (11 bands). This method appeared very powerful to recognize the rose sections and to set up a marker hierarchy which places at the first level the flavonol hetero­ side pattern, then the morphological data, the SOD isozyme data and finally the anthocyanin pattern. The correlation studies between the markers underlined the relatively common view by means of flavonol patterns and the morphological features
A New psbA Mutation Yielding an Amino-Acid Exchange at the Lumen-Exposed Site of the D1 Protein
Authors: Schwenger-Erger C. , Böhnisch N. , Barz W.
Published: August 2018

In eight metribuzin-resistant photoautotrophic cell cultures of Chenopodium rubrum (Thiemann and Barz, 1994 a, b) sequence analyses of a part of the psbA gene coding for the photosystem -II D1 protein had revealed different double and triple mutations within the herbicide binding niche of the protein (Schwenger-Erger et al., 1993). Two pairs of the exam­ined cell lines carried identical mutations within this part of the protein, although their growth performance and their herbicide resistance patterns were different, both at the cellu­lar and the thylakoid level. Starting from the known part of the psbA gene we have amplified the remaining psbA sequences using inverse polymerase chain reaction. Thus the complete sequence of the coding part of the gene was elucidated. After sequence analyses we found an additional amino acid exchange at the position 184 (ile → asn) of the D1 protein in cell line L1. Metabolic consequences of this mutation are discussed. Partial sequence analyses of the psbD gene of the herbicide resistant cell culture lines revealed no mutation within that part o f the D2 protein, which is in direct contact with the D1 protein.
Visualization of Glutathione Conjugation and Inducibility of Glutathione S-Transferases in Onion {Allium cepa L.) Epidermal Tissue
Authors: Schröder Peter , Stampfl Andreas
Published: August 2018

Glutathione conjugation of 1-chloro-2,4-dinitrobenzene, 1,2-dichloro-4-nitrobenzene, NBD-Cl, monobromobimane and monochlorobimane was found to occur in epidermal tissue of onion bulbs (Allium cepa L.). Conjugation required the presence of glutathione S-transferases (GST). In order to follow glutathione conjugation microscopically, bimanes were utilized. Monochlorobimane was converted to a brightly fluorescing conjugate that was shown to be transported to the nucleus before sequestration in the vacuole occurred. GST activity was stimulated as well as induced by several electrophilic xenobiotics, by cycloheximide and by several glutathione conjugates. γ-Glutamylcysteine conjugates that are formed during enzymatic cleavage of glutathione conjugates in plants, were not active as inducers of enzyme activity. In the light of the stimulating effects of xenobiotic glutathione conjugates on GST activity, it is concluded that glutathione conjugates may act as signal molecules.
The Anticancer Drug Chlorambucil Interacts with the Human Erythrocyte Membrane and Model Phospholipid Bilayers
Authors: Suwalsky Mario , Hernández Pedro , Villena Fernando , Sotomayor Carlos P.
Published: August 2018

The plasma membrane has gained increasing attention as a possible target of antitumor drugs. It has been reported that they act as growth factor antagonists, growth factor receptor blockers, interfere with mitogenic signal transduction or exert direct cytotoxic effects. Chlorambucil (4-[p-(bis[2-chloroethyl]amino)phenyl]butyric acid) is an alkylating agent widely used in the treatment of chronic lymphocytic leukaemia. Contradictory reports have been published concerning its interaction with cell membranes. Whereas a decrease in the fluidity of Ehrlich ascite tumor cells has been adduced, no evidences were found that chlorambucil changes membrane lipid fluidity and alkylating agents had effects in these systems even at highly toxic concentrations. Our results showed that chlorambucil at a dose equivalent to its therapeutical concentration in the plasma (3.6 μm) caused the human erythrocyte membrane to develop cup-shaped forms (stomatocytes). Accordingly to the bilayer couple hypothesis, this means that the drug is inserted into the inner monolayer of the erythrocyte membrane, a conclusion supported by X-ray diffraction performed on multilayers of dimyristoylphosphatidylcholine (DMPC) and dimyristoylphosphatidylethanolamine (DMPE), representative of phospholipid classes located in the outer and inner monolayers of the erythrocyte membrane, respectively. It is concluded that the cytotoxic effect of chlorambucil might be due to alteration of the structure and therefore of the physiological properties of cell membranes such as fluidity, permeability, receptor and channel functions.
Pentacyclic Triterpenoid Alkanoates in Propolis
Authors: Santos Pereira Alberto dos , Mendes da Silva Joaquim Fernando , Kiltzke Renata , Cardoso Jari Nobrega , de Aquino Neto Francisco Radler
Published: August 2018

A series of high molecular mass pentacyclic terpenoid wax esters (TTFAE) were characterized for the first time in hexane extracts of Brazilian propolis (Carangola, Minas Gerais State). Identification was by HT-HRGC (High Temperature High Resolution Gas Chromatography) and HT-HRGC coupled to mass spectrometry (HT-HRGC-MS).
Instability of Three-Dimensional Structures in Ribosomal Cores Evidenced by Microcalorimetric Studies
Authors: Bonincontro Adalberto , Cinelli Stefania , Onori Giuseppe , Risuleo Gianfranco
Published: August 2018

In this paper we show a microcalorimetric investigation carried out on the so-called cores, i. e. ribosomes deprived of select proteins by LiCl treatment. Thermal degradation of native ribosomes gives rise to two thermal transitions occurring at different temperatures. In the cores the high temperature peak persists even after treatment at very high ion strength (2 м LiCl). This strongly suggests the existence of a very stable structure that was previously observed also in particles treated with agents that hydrolyze the RNA moiety. The low temperature peak gradually but dramatically decreases even though it never disappears completely This indicates that the treatment to obtain ribosomal cores does not cause complete unfolding of the particle but only the destabilization of a structural three-dimensional domain present in native ribosomes. These data are discussed in the light of previous results obtained by dielectric spectroscopy and microcalorimetric studies on ribosomal particles.
Localisation of a 3-Hydroxy-3-methylglutaryl-Coenzyme A Reductase in the Mitochondrial Matrix of Trypanosoma brucei Procyclics
Authors: Heise Norton , Opperdoes Fred R.
Published: August 2018

Contrary to Leishmania spp. and Trypanosoma cruzi, Trypanosoma brucei bloodstream forms do not synthesise their own sterols but take these compounds in the form of cholesterol directly from the mammalian host. However, procyclic insect stages synthesise ergosterol rather than cholesterol. Here the sub-cellular localisation of the first committed enzyme of this pathway of isoprenoid synthesis 3-hydroxy-3-methylglutaryl-coenzyme A reductase in T. brucei procyclics (0.9 nmol. min-1 . mg-1 protein) was carried out using both cell-fractionation by isopycnic centrifugation and digitonin-titration experiments. The majority of the NADP+- linked 3-hydroxy-3-methylglutaryl-coenzyme A reductase is a soluble enzyme present in the mitochondrial matrix with some additional membrane-associated activity in glycosomes and possibly in the endoplasmic reticulum. It is suggested that the active metabolism of threonine and/or leucine as preferred 2-carbon source for the incorporation of acetyl units into lipids and/or sterols in the mitochondrion of T. brucei procyclics is the explanation for a high 3- hydroxy-3-methylglutaryl-coenzyme A reductase activity in these protozoan organelles.
The in vitro Anti-Fungal and Anti-Bacterial Activities of β-Sitosterol from Senecio lyratus (Asteraceae)
Authors: Kiprono Paul C. , Kaberia Festus , Keriko Joseph M. , Karanja John N.
Published: August 2018

From a methanol extract of dried-ground aerial parts of Senecio lyratus, an anti-fungal and anti-bacterial active compound was isolated and identified as β-sitosterol by spectroscopic analysis.
Prevalence of Multi-Drug Resistant Salmonella typhi among Clinically Diagnosed Typhoid Fever Patients in Lagos, Nigeria
Authors: Akinyemi Kabir’ O. , Coker Akintoye O. , Olukoya Daniel K. , Oyefolu Akeeb O. , Amorighoye Eriwu P. , Omonigbehin Emmanuel O.
Published: August 2018

A total of 635 clinically diagnosed typhoid fever patients were bled from three different health institutions in the metropolis of Lagos, Nigeria over a period of 15 months, May 1997 to July 1998.

Out of the total blood cultured, 101 (15.9% ) isolates of Salmonella species were isolated of which 68 (67.3% ) were S. typhi, 17 (16.8% ) and 16 (15.8% ) were S. paratyphi A and S. arizonae respectively. The overall isolation rate of S. typhi among patients is 10.7% , with most isolates 45.9% found among the severely-ill young adults, age group 1 6 -30 years. All isolates were subjected to anti-microbial susceptibility testing using 12 different antibiotics: chloramphenicol, ampicillin, cotrimoxazole, gentamicin, colistin sulfate, nalidixic acid, nitrofurantoin, cefotaxime, tetracycline, streptomycin, ofloxacin and ciprofloxacin. All the S. typhi and S. paratyphi A isolates showed resistance to two or more of the 10 of 12 antibiotics tested particularly the 3-first-line antibiotics commonly used (chloramphenicol, ampicillin and cotrim oxazole) in the treatment of typhoid fever in Nigeria. No isolate showed resistance to ofloxacin and ciprofloxacin, however, nalidixic acid and gentamicin showed a moderate and appreciable inhibition to most of our isolates.
Betalains and Phenolics in Red Beetroot (Beta vulgaris) Peel Extracts: Extraction and Characterisation
Authors: Kujala Tytti , Loponen Jyrki , Pihlaja Kalevi
Published: August 2018

The extraction of red beetroot (Beta vulgaris) peel betalains and phenolics was compared with two extraction methods and solvents. The content of total phenolics in the extracts was determined according to a modification of the Folin-Ciocalteu method and expressed as gallic acid equivalents (GAE). The profiles of extracts were analysed by high-performance liquid chromatography (HPLC). The compounds of beetroot peel extracted with 80% aqueous methanol were characterised from separated fractions using HPLC- diode array detection (HPLC-DAD) and HPLC- electrospray ionisation-mass spectrometry (HPLC-ESI-MS) techniques. The extraction methods and the choice of solvent affected noticeably the content of individual compounds in the extract. The betalains found in beetroot peel extract were vulgaxanthin I, vulgaxanthin II, indicaxanthin, betanin, prebetanin, isobetanin and neobetanin. Also cyclodopa glucoside, N-formylcyclodopa glucoside, glucoside of dihydroxyindolcarboxylic acid, betalamic acid, ʟ-tryptophan, p-coumaric acid, ferulic acid and traces of unidentified flavonoids were detected.
Seasonal Variation of the Chemical Constituents from Croton Species
Authors: Santos Pereira Alberto dos , do Amaral Ana Claudia Fernandes , Araujo Silva Margareth de , Aquino Neto Francisco Radler de
Published: August 2018

The terpenes, sterols, alkaloid (glaucine) and α-tocopherol show seasonal variation for Croton hemiargyreus hemiargyreus and Croton echinocarpus. The amounts of triterpenes are higher during the tropical summer and in most samples the major sesquiterpene was characterized as caryophyllene. The seasonal variation of glaucine showed a maximum between June and October for C. hemiargyreus, and was present only in January and June in C. echinocarpus.
Effect of Membrane Fluidity on Photoinhibition of Isolated Thylakoids Membranes at Room and Low Temperature
Authors: Velitchkova Maya , Popova Antoaneta , Markova Tzvetelina
Published: August 2018

The relationship between thylakoid membrane fluidity and the process of photoinhibition at room and low (4 °C) temperature was investigated. Two different membrane perturbing agents - cholesterol and benzylalcohol were applied to manipulate the fluidity of isolated pea thylakoids. The photochemical activity of photosystem I (PSI) and photosystem II (PSII), polarographically determined, were measured at high light intensity for different time of illumination at both temperatures. The exposure of cholesterol- and benzylalcohol-treated thylakoid membranes to high light intensities resulted in inhibition of both studied photochemical activities, being more pronounced for PSII compared to PSI. Time dependencies of inhibition of PSI and PSII electron transport rates for untreated and membranes with altered fluidity were determined at 20 °C and 4 °C. The effect is more pronounced for PSII activity during low-temperature photoinhibition. The data are discussed in terms of the determining role of physico-chemical properties of thylakoid membranes for the response of photosynthetic apparatus to light stress.
Counterion Effects on Interaction of Amphiphilic Quaternary Ammonium Salts with Model Membranes
Authors: Różycka-Roszak Bożenna , Żyłka Romuald , Kral Teresa , Przyczyna Adriana
Published: August 2018

The micellization as well as the interaction with model membranes of dodecyltrimethylammonium halides (DTAX) and N-dodecyl-N,N-dimethyl-N-benzylammonium halides (DBeAX) were studied at 298K and 313K by means of titration calorimetry. The calorimetric curves reflect both the counterion and benzyl group effects on the interaction of the surfactants studied with the lipid bilayer. Bromide as counterion enhanced the interactions more than chloride of both DTAX and DBeAX compounds with model membranes.

Further, we studied the influence of DTAX and DBeAX on calcium ion desorption from the liposome membrane using a radioactive tracer method. DBeAX proved more efficient in desorption of calcium than DTAX. Iodides of these compounds enhanced this process more than bromides and chlorides.
Sex Pheromone of the Carpenterworm, Holcocerus insularis (Lepidoptera, Cossidae)
Authors: Jintong Zhang , Yan Han , Xianzuo Meng
Published: August 2018

By means of thin-layer chromatography (TLC), electroantennogram (EAG), gas chromatography (GC), gas chromatography-mass spectrometry (GC-MS) and field tests, (Z)-3-tetradecenyl acetate(Z3-14:Ac), (E)-3-tetradecen-1-ol(E3-14:OH), and (Z)-3-tetradecen-1-ol(Z3- 14:OH) at a ratio of 51:39:10 were identified from the female sex pheromone gland extracts of the carpenterworm, Holcocerus insularis Staudinger (Lepidoptera, Cossidae). The average amounts of Z3-14:Ac, E3-14:OH and Z3-14:OH in a single sex pheromone gland of calling moth were 7.29±2.72 ng, 5.72±2.43 ng and 1.44±0.56 ng, respectively. This is the first time that Z3-14:Ac was identified as a component of lepidopteran sex pheromone. Traps baited with rubber septa impregnated with Z3-14:Ac (500 μg / septum) were more effective than the traps baited with virgin female. The addition of the E3-14:OH and Z3-14:OH to rubber septa baited with Z3-14:Ac did not modify H. insularius male attraction, but E3-14:Ac slightly enhanced trap catch.
Tannins and Related Compounds: Killing of Amastigotes of Leishmania donovani and Release of Nitric Oxide and Tumour Necrosis Factor a in Macrophages in vitro
Authors: Kiderlen Albrecht F. , Kayser Oliver , Ferreira Daneel , Kolodziej Herbert
Published: August 2018

The antileishmanial and immunomodulatory potencies of a series of 28 polyphenols were evaluated in terms of extra- and intracellular leishmanicidal activity and macrophage activation for release of nitric oxide (NO), tumour necrosis factor (TNF) and interferon (IFN)- like properties. For this, several functional bioassays were employed including an in vitro model for leishmaniasis in which murine bone marrow-derived macrophages (BMMΦ) were infected with the obligate intracellular parasite Leishmania donovani, an extracellular Leishmania proliferation assay, a fibroblast-lysis assay (TNF-activity), and a biochemical assay for NO. Except for gallic acid, its methyl ester, shikimic acid and catechin (EC50 25.8-67.9 nᴍ) all polyphenols tested significantly inhibited the intracellular survival of L. donovani amastigotes (EC50 0.4 -13.9 nᴍ) when compared with the clinically used agent, sodium stibogluconate (EC50 10.6 nᴍ). In contrast, none of the samples proved to be directly toxic for the extracellular promastigote form of the parasite. Noteworthy, the phenolic samples showed only moderate or no cytotoxicity against the murine host cells (EC50 10 to >144 nᴍ). Although NO is an important effector molecule in macrophage microbicidal activity, the inducing potential of the test compounds for its release was found to be very moderate ranging from 7-54 μm (IFN-γ/LPS 119 μm). On the other hand, inhibition of NO production had no apparent effect on intracellular leishmanicidal activity of polyphenols. Their in vitro TNFinducing potential producing 50% lysis in murine L929 cells increased in the order of simple phenols and flavanols (34-48 U/ml) < A-type proanthocyanidins (53 -80 U/ml) < B-type proanthocyanidins (64-200 U/ml) < hydrolyzable tannins (287-350 U/ml) at the host cell subtoxic concentration of 50 μg/ml. Furthermore, gallic acid and some hydrolyzable tannins showed appreciable IFN-like activities ( 14-23 U/ml) as reflected by inhibition of the cytopathic effect of encephalomyocarditis virus on fibroblast L 929 cells. The results provide a rational basis for the recorded anti-infectious efficacy of traditionally used herbal medicines containing tannins in vivo, in the light of both only moderate direct antimicrobial activities of distinct polyphenols in vitro and the limited knowledge on their uptake in humans.
Editorial
Authors: Knack Eduardo Roberto Jordão , Poloni Rita Juliana Soares
Published: August 2018

Gaston Bachelard (2008, p.3), em sua obra "A poética do espaço", coloca aseguinte questão: "como uma imagem por vezes muito singular pode revelar-se como uma concentração de todo o psiquismo?". O filósofo assume que algumas imagens são tão fortes que causam um impacto profundo no observador, produzindo e despertando uma miríade de sentimentos que são desencadeados nessa relação entre o sujeito que observa e o objeto observado. Essas emoções só despertam nesse momento por guardarem uma íntima relação com a memória.
Evaluation of Cost Savings and Perceptions of an Open Textbook in a Community College Science Course
Authors: Fisher Matthew R.
Published: August 2018

Open textbooks are free, online resources that can replace traditional textbooks and save students money. The costs of traditional textbooks continue to increase, and this can particularly affect at-risk, low-income students. Few studies have analyzed student perceptions of open textbooks and how they influence academic achievement, but the emerging trend is positive. In the present study, I assessed student perceptions of an open textbook and calculated the subsequent cost savings. Although there were some limitations to my study, such as a low sample size, my results closely mirror previous studies in that most students had favorable opinions of the open textbook and would prefer to use them over traditional textbooks. The average cost savings per student was $81 for one course, determined using a novel method that does not assume all students buy new textbooks. These savings were likely important to the students, the majority of whom worked five hours or more and have received Pell Grants or other tuition waivers.
The Politics of Energy and Climate Change in Japan under Abe
Authors: Incerti Trevor , Lipscy Phillip Y.
Published: August 2018

Under what we call Abenergynomics, Japanese Prime Minister Abe Shinzō has used energy policy to support the growth objectives of Abenomics, even when the associated policies are publicly unpopular, opposed by utility companies, or harmful to the environment. We show how Abenergynomics has shaped Japanese policy on nuclear power, electricity deregulation, renewable energy, and climate change.
Retinoid Signaling Controlled by SRC-2 in Decidualization Revealed by Transcriptomics
Authors: Szwarc Maria Magdalena , Hai Lan , Gibbons William E , White Lisa D , Mo Qianxing , Kommagani Ramakrishna , Lanz Rainer B , DeMayo Francesco J , O'Malley Bert W , Lydon John P
Published: August 2018

Establishment of a successful pregnancy requires not only implantation of a healthy embryo into a receptive uterus but also progesterone receptor (PGR)-dependent transformation of endometrial stromal cells (ESCs) into specialized decidual cells. Decidual cells support the developing embryo and are critical for placentation. We have previously shown that a known transcriptional coregulator of the PGR, Steroid Receptor Coactivator-2 (SRC-2), is a critical driver of endometrial decidualization in both human and mouse endometrium. However, the full spectrum of genes transcriptionally controlled by SRC-2 in decidualizing ESCs has not been identified. Therefore, using an RNA- and chromatin immunoprecipitation-sequencing approach, we have identified the transcriptome of decidualizing human ESCs (hESCs) that requires SRC-2. We revealed that the majority of hESC genes regulated by SRC-2 are associated with decidualization. Over 50% of SRC-2-regulated genes are also controlled by the PGR. While ontology analysis showed that SRC-2-dependent genes are functionally linked to signaling processes known to underpin hESC decidualization, cell membrane processes were significantly enriched in this analysis. Follow-up studies showed that retinoid signaling is dependent on SRC-2 during hESC decidualization. Specifically, SRC-2 is required for full induction of the retinol transporter, Stimulated by Retinoic Acid 6 (STRA6), which is essential for hESC decidualization. Together our findings show that a critical subset of genes transcriptionally reprogramed by PGR during hESC decidualization requires SRC-2. Among the multiple genes, pathways, and networks that are dependent on SRC-2 during hESC decidualization, first-line analysis supports a critical role for this coregulator in maintaining retinoid signaling during progesterone driven decidualization.