Zeitschrift fur Naturforschung - Section C Journal of Biosciences
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Stimulation of Phosphatidylinositol Phosphorylation in the Sarcoplasmic Reticular Ca<sup>2+</sup>-Transport ATPase by Vanadate Vanadate increases the initial phosphatidylinositolphosphate formation rate as well as the steady state level of the above lipid phosphate when phosphatidylinositol associated with the isolated Ca2+ transport ATPase is phosphorylated either by the membrane bound endogeneously present phosphatidylinositol-kinase or by exogeneously added lipid kinase. Employing an ultrasonicated mixture of pure phosphatidylinositol and Triton X 100 (without membrane proteins) no vanadate effect can be seen. This vanadate effect is probably not mediated through the lipid kinase activity, but more likely, through conformational changes of the Ca2+ transport ATPase protein. Such conformational changes would lead to a higher degree of phosphatidylinositol exposed on the Ca2+ transport ATPase and thus a higher substrate concentration. Consequently, the initial phosphatidylinositolphosphate formation rate and steady state level increase.
Zeitschrift fur Naturforschung - Section C Journal of Biosciences - Tập 41 Số 3 - Trang 310-314 - 1986
Chemical Composition of the Essential Oil of Phlomis linearis Boiss. & Bal., and Biological Effects on the CAM-Assay: A Safety Evaluation Abstract
Phlomis linearis Boiss. & Bal. of the Lamiaceae family growing in central, east and southeast Anatolia is an endemic species for Turkey. The essential oil obtained from the aerial parts by hydro distillation was subsequently analyzed by GC/MS. The main components of the oil were found as β-caryophyllene (24.2%), germacrene D (22.3%) and caryophyllene oxide (9.2%), among 49 identified compounds, representing 94.5% of the total essential oil. The overall biological activity of the essential oil (100 μg/pellet) was tested on the chorioallantoic membrane (CAM) of the fertilized hen’s egg in order to examine the anti-angiogenic and anti-inflammatory activity. None of the tests showed pronounced activity, toxicity or irritation at the tested concentration.
Zeitschrift fur Naturforschung - Section C Journal of Biosciences - Tập 58 Số 11-12 - Trang 826-829 - 2003
A Simple Coding Procedure Enhances a Neuron's Information Capacity Abstract
The contrast-response function of a class of first order intemeurons in the fly's compound eye approximates to the cumulative probability distribution of contrast levels in natural scenes. Elementary information theory shows that this matching enables the neurons to encode contrast fluctuations most efficiently.
Zeitschrift fur Naturforschung - Section C Journal of Biosciences - Tập 36 Số 9-10 - Trang 910-912 - 1981
Epicuticular Leaf Flavonoids from Eucalyptus Species and from Kalmia latifolia Abstract
In young plants of Eucalyptus globulus the leaves are covered with a whitish epicuticular layer. This leaf wax contains small amounts of C-methylated flavones as aglycones. A novel flavone has now been identified as 5,4′-dihydroxy, 7-methoxy, 6-methyl-flavone (8-desmethyl-sideroxylin). Another minor external flavone is chrysin. On leaves of E. sieberi the flavanone pinocembrin could be detected. It is shown that the four C-methylated flavones, eucalyptin, 8-desmethyl-eucalyptin, sideroxylin, and 8-desmethyl-sideroxylin are present in the leaf wax of 8 species analyzed. The same flavones are present on leaves of Kalmia latifolia.
Zeitschrift fur Naturforschung - Section C Journal of Biosciences - Tập 36 Số 11-12 - Trang 913-915 - 1981
Targeted Deletion Mutagenesis of the β Subunit of Cytochrome b<sub>559</sub> Protein Destabilizes the Reaction Center of Photosystem II Abstract
Oligonucleotide-directed mutagenesis techniques were used to delete the psbF gene, encoding the β subunit of the cytochrom e b559 protein of the photosystem II complex in the cyano bacterium, Synechocystis 6803. Cyt b559 is an integral com ponent of PS II complex. However, its precise functional role in PS II remains to be determined. Previously, we created a mutant in which the psbF gene as well as three of its neighbouring genes, psbE , psbL and p sb i were simultaneously deleted from the chrom osom e of Synechocystis 6803 (Pakrasi, Williams and Arntzen, EMBO J. 7, 325 -332 , 1988). This mutant had no PS II activity. However, the role of any one of the four individual gene products could not be determined by studying this mutant. The newly generated mutant, T 256, had only one gene, p sbF , deleted from the genome. This mutant was also impaired in its PS II activities. In addition, it had barely detectable levels of two other protein com ponents, D1 (herbicide binding protein) and D2, of the reaction center of PS II, in its thylakoid membranes. In contrast, two other proteins of PS II, CP47 and CP43 were present in appreciable amounts. Fluorescence spectra (77 K) of the mutant showed the absence of a peak at 695 nm that was previously believed to originate from CP47. In addition, phycobilisomes, the light-harvesting antenna system of PS II, were found to be assembled normally in this mutant. We conclude that the presence of the β subunit of Cyt b559 in the thylakoid membranes is critically important for the assembly of PS II reaction center.
Zeitschrift fur Naturforschung - Section C Journal of Biosciences - Tập 45 Số 5 - Trang 423-429 - 1990
Effect of pH on xylitol production by <i>Candida</i> species from a prairie cordgrass hydrolysate Abstract
Using hydrolysates of the North American prairie grass prairie cordgrass buffered at pH 4.5, 5.0, 5.5 or 6.0, xylitol production, xylitol yield, cell biomass production and productivity were investigated for three strains of yeast Candida . Of the three strains, the highest xylitol concentration of 20.19 g xylitol (g xylose consumed)−1 and yield of 0.89 g xylitol (g xylose consumed)−1 were produced by Candida mogi ATCC 18364 when grown for 120 h at 30° C on the pH 5.5-buffered hydrolysate-containing medium. The highest biomass level being 7.7 g cells (kg biomass)−1 was observed to be synthesized by Candida guilliermondii ATCC 201935 after 120 h of growth at 30° C on a pH 5.5-buffered hydrolysate-containing medium. The highest xylitol specific productivity of 0.73 g xylitol (g cells h)−1 was determined for C. guilliermondii ATCC 20216 after 120 h of growth at 30°C on a pH 5.0-buffered hydrolysate-containing medium. Xylitol production and yield by the three Candida strains was higher on prairie cordgrass than what was previously observed for the same strains after 120 h at 30° C when another North American prairie grass big bluestem served as the plant biomass hydrolysate indicating that prairie cordgrass may be a superior plant biomass substrate.
Zeitschrift fur Naturforschung - Section C Journal of Biosciences - Tập 75 Số 11-12 - Trang 489-493 - 2020
The Dorsal Compound Eye of Simuliid Flies: Abstract
Compound Eye, Light-Quantum Noise The highly specialized dorsal compound eye of male Simuliids is especially adapted to detect during flight the females which are very small animals (1×3 mm). At dawn, the eye functions close to the physical limit imposed by the quantum fluctuations of light. In bright illuminations, light-qauntum noise is not a limiting factor as can be shown by behavioural experiments.
Zeitschrift fur Naturforschung - Section C Journal of Biosciences - Tập 31 Số 11-12 - Trang 764-765 - 1976
Factors Controlling Medium-Chain Fatty Acid Synthesis in Plastids from Maturing Cuphea Embryos Abstract
The colorless embryos of Cuphea wrightii A. Gray accumulate capric (about 30%) and lauric acid (about 50%) in their storage lipids. Fractionation studies show that the capacities for the synthesis of these medium-chain fatty acids (MCFA) from [1-14 C]acetate were strictly bound to intact plastids. These, in turn, obligately required the addition of ATP. ATP could partially be substituted by ADP. Reduction of the pyridine nucleotide pool, required for optimum MCFA formation within the plastids, was driven by glucose 6-phosphate. Under these conditions the plastids were capable of synthesizing MCFA like the intact tissue. The presence of CoA in the incubation medium induced acyl-CoA formation.
The observed accumulation of unesterified capric and lauric acid in the absence of CoA suggests that acyl-ACP thioesterase activity is involved in the chain termination. Treatment with cerulenin led to an unexpectedly small reduction of total fatty acid synthesis while the chain elongation of capric acid was clearly inhibited. A similar accumulation of capric acid at the expense of longer chain fatty acids has been observed after replacing ATP by ADP. These findings implicate that even the condensing enzymes are involved in the control of chain termination.
Zeitschrift fur Naturforschung - Section C Journal of Biosciences - Tập 48 Số 7-8 - Trang 616-622 - 1993
Cooperative Binding of the Organophosphate Paraoxon to the (Na<sup>+</sup> + K<sup>+</sup>)-ATPase Abstract
Paraoxon. the main active metabolite of the organophosphorus insecticide parathion. exerted a dose-dependent inhibitory effect on the activity of pig kidney (Na+ + K+ )-ATPase contained in microsomal fraction and purified from it. Substrate kinetics studies revealed the existence of two active sites with high and low affinity to ATP. The Dixon analysis of the mode of the inhibition indicated its noncompetitive character. The purified enzyme was more affected than enzyme contained in the microsomal fraction. The inhibition constant K, ranged from 73 to 246 μm depending on the type of preparation. The Hill coefficient (n) fulfilled the relationship 1<n<3. These properties of the interaction suggest the cooperative binding of paraoxon to the enzyme. An indirect mechanism of the interaction was proposed: paraoxon could inhibit the activity of the (N a+ + K+ )-ATPase by excluding the enzyme protein from its normal lipid milieu
Zeitschrift fur Naturforschung - Section C Journal of Biosciences - Tập 50 Số 9-10 - Trang 660-663 - 1995
Isolation and Characterization of a New Arthrospira Strain A filamentous microorganism, morphologically similar to the cyanobacterium Arthrospira, was isolated from Mangueira Lagoon in Brazil, from which Arthrospira has not previously been isolated. Random amplified polymorphic DNA (RAPD) comparison with the standard Arthrospira platensis strains LEB 52 and Paracas indicated that the organism isolated was an Arthrospira isolate, which we denominated strain LEB 18. The RAPD analysis showed conserved sequences which indicated that the three strains belonged to the same genus, and were all Arthrospira species, but there were sufficient differences between them suggesting that they were separate strains. The strain LEB 18 was cultivated in undiluted Zarrouk medium and in 60% and 20% (v/v) Zarrouk medium diluted with sterilized Mangueira Lagoon water (MLW) using illuminance rates of 32.5, 45.5 and 58.5 μmol m−2 s−1 according to a complete 32 factorial design with a triplicate central point. The strains LEB 52 and Paracas were cultived in the conditions central point. Our new isolate produced the highest specific growth rate (μmax = 0.22 d−1 ) in 60% Zarrouk medium diluted with MLW and illuminated with 58.5 μmol m−2 s−1 and the highest protein content (86.0% w/w).
Zeitschrift fur Naturforschung - Section C Journal of Biosciences - Tập 63 Số 1-2 - Trang 144-150 - 2008
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