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Growth line analysis of diagenetically altered scleractinians is only possible if carbonate diagenesis has followed the pathway of aragonite leaching and coeval formation of low magnesium calcite. All other possibilities of aragonite transformation into calcite exclude the preservation of this growth line banding. Examples of these diagenetic patterns are found in the Pleistocene of Barbados.  相似文献   
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Heterogeneity of high affinity LSD-binding sites was confirmed by displacement studies with 2-bromo (+)—LSD and with apamin, a peptide neurotoxin. In line with the concept of multiple binding sites, a number of fractions of putative endogenous ligands could be separated from rat brain extract. The LSD-displacing β-fraction was not detectable in tissues lacking high affinity LSD-binding sites. High affinity dopamine- and serotonin-binding was differentially affected by the β-fraction.  相似文献   
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PalZ - Hyperostotic fish bones from the presumable Pliocene phosphate-bearing deposits along Lake Manyara, Tanzania, are described. In contrast to marine occurrences of this kind, the pathological...  相似文献   
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The effect of hydroxyperoxyoctadecadienoic acid, e.g. 13-hydroperoxy-cis,9,trans-11-octadecadienoic acid, on the autooxidation of linoleic acid induced by superoxide radical was examined in a system containing xanthine oxidase, acetaldehyde, and diethylenetriaminepentaacetic acid dissolved in an aqueous phosphate buffer containing 10% ethanol. The superoxide radical is required for autooxidation, as shown by essentially complete inhibition on the addition of superoxide dismutase. Pure linoleic acid was not readily oxidized, but the addition of lipid hydroperoxide markedly stimulated the autooxidation. Addition of 2.8 microM FeCl3 did not produce an increase in the rate of xanthine oxidase-induced autooxidation. Spontaneous autooxidation, a process slower than xanthine oxidase-induced autooxidation, was detectable on the time scale of these observations but was slower than the xanthine oxidase-induced autooxidation. Initiation of linoleic acid autooxidation is postulated to result from a reaction between superoxide and lipid hydroperoxide. The nature of this reaction is uncertain, but it does not appear to depend on iron catalysis.  相似文献   
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Synaptosomal plasma membranes from mammalian brain contain protein kinase activity which phosphorylates endogenous membrane proteins and is stimulated by cyclic AMP. Using polyacrylamide gel electrophoresis it was shown that at least ten proteins in the synaptosomal plasma membrane fraction could be phosphorylated by endogenous cyclic AMP-stimulated protein kinase activity. The number of proteins whose phosphorylation was stimulated by cyclic AMP was strongly influenced by the pH and Mg2+ concentration used in the phosphorylation reaction. A complex pattern of cyclic AMP-stimulated protein phosphorylation was obtained only with synaptosomal plasma membranes and a crude microsomal fraction. Mitochondrial and myelin fractions exhibited no cyclic AMP-stimulated protein kinase activity. Investigation of the distribution of substrates for cyclic AMP-stimulated phosphorylation among various brain regions failed to reveal any regional differences.  相似文献   
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Synaptosomal plasma membranes from mammalian brain contain protein kinase activity which phosphorylates endogenous membrane proteins and is stimulated by cyclic AMP. Using polyacrylamide gel electrophoresis it was shown that at least ten proteins in the synaptosomal plasma membrane fraction could be phosphorylated by endogenous cyclic AMP-stimulated protein kinase activity. The number of proteins whose phosphorylation was stimulated by cyclic AMP was strongly influenced by the pH and Mg2+ concentration used in the phosphorylation reaction. A complex pattern of cyclic AMP-stimulated protein phosphorylation was obtained only with synaptosomal plasma membranes and a crude microsomal fraction. Mitochondrial and myelin fractions exhibited no cyclic AMP-stimulated protein kinase activity. Investigation of the distribution of substrates for cyclic AMP-stimulated phosphorylation among various brain regions failed to reveal any regional differences.  相似文献   
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