ABSTRACT
Sodium chloride stimulated catalysis of oxidation of phosphatidylcholine liposomes by the soluble fraction of mackerel muscle. Chloride was determined to be the active component of the salt in this system. Sulfate also stimulated lipid oxidation. No difference was observed with either anion among sodium, potassium, or lithium cations. Redox iron was involved in the chloride stimulation of lipid oxidation by the press juice. Part of the chloride stimulation of the press juice was mediated through the high molecular weight (greater than 5 kdalton) fraction. Chloride improved the pro-oxidative effect of ascorbate on rat liver ferritin in vitro. It did not appear that production of chlorine radical by peroxidase was involved in the stimulatory effect of chloride.
Subject(s)
Lipid Peroxidation/drug effects , Muscles/metabolism , Sodium Chloride/pharmacology , Acetylcysteine/pharmacology , Animals , Calcium Chloride/pharmacology , Catalysis/drug effects , Ceruloplasmin/pharmacology , Fishes , Liposomes/metabolism , Muscles/drug effects , Solubility , Strontium/pharmacologyABSTRACT
The purification procedure for isolating sn-glycerol-3-phosphate dehydrogenase (EC 1.1.1.8) from Saccharomyces cerevisiae was improved by the introduction of an ion-exchange step. Enzyme yields were doubled and the specific activity was increased as compared to the original procedure. A new value of 42,000 was obtained for the molecular weight by several denaturing methods. By native gel chromatography the molecular weight appears to be 31,000 as reported earlier. Michaelis constants were found to be 0.37 mM with dihydroxyacetone phosphate as the variable substrate and 0.018 mM for NADH as the variable substrate.
Subject(s)
Glycerolphosphate Dehydrogenase/isolation & purification , Saccharomyces cerevisiae/enzymology , Chemical Precipitation , Chromatography , Electrophoresis, Polyacrylamide Gel , Glycerolphosphate Dehydrogenase/metabolism , Kinetics , Molecular WeightABSTRACT
Organ cultures of the guinea pig hypothalamo-neurohypophysial complex could be maintained for periods as long as 3 weeks. Morphological studies using conventional light microscopy as well as electron microscopy indicate that neurosecretory cells remain viable during this time. Biochemical studies show that the capability of the cultures to synthesize a normal spectrum of cellular RNA species is impaired during the initial day in culture, but that this capability is restored after 4-5 days. Similarly, protein synthesis proceeds at low levels during initial days of culture, but increases after 5 days. These phenomena appear to be independent of changes in the specific radioactivity of precursor pools and were also observed when outgrowth of non-neuronal cells is inhibited with fluorodeoxyuridine. The content of vasopressin, a product of a specific class of neurosecretory neurons, was found to decrease in the posterior pituitary during 7 - 10 days in culture by 50-70 percent; the levels then plateaued and were maintained for up to 3 weeks. The hypothalamic content of the hormone was relatively constant throughout the culture period. Of most importance was the demonstration that the organ cultures were capable of vasopressin biosynthesis. This capability paralleled the biosynthetic activity of RNA and gross protein metabolism in that there was an initial refractory period of several days duration.
Subject(s)
Hypothalamo-Hypophyseal System , Organ Culture Techniques , Animals , Cell Survival , DNA/metabolism , Floxuridine/pharmacology , Guinea Pigs , Hypothalamo-Hypophyseal System/anatomy & histology , Hypothalamo-Hypophyseal System/metabolism , Hypothalamus/metabolism , Hypothalamus/ultrastructure , Male , Nerve Tissue Proteins/biosynthesis , Pituitary Gland/ultrastructure , Pituitary Gland, Posterior/metabolism , RNA/biosynthesis , RNA/metabolism , Time Factors , Vasopressins/biosynthesis , Vasopressins/metabolismSubject(s)
Hypothalamus/metabolism , Nerve Tissue Proteins/metabolism , Neuroglia/metabolism , Pituitary Gland, Posterior/metabolism , RNA/metabolism , Animals , Autoradiography , Body Weight , Buffers , Carbon Isotopes , DNA/metabolism , Hypothalamo-Hypophyseal System , In Vitro Techniques , Microscopy, Electron , Neurosecretion , Nucleotidyltransferases/metabolism , Rats , Ribonucleases/metabolism , Starvation/metabolism , Tritium , Uracil Nucleotides/metabolism , Vasopressins/metabolism , Water DeprivationABSTRACT
Fragments of the anterior hypothalamus that contain supraoptic nuclei and short axonal segments from adult guinea pigs have been kept in organ culture for up to 15 days. Electron micrographs displayed intact nuclei, Nissl substance, Golgi bodies, and an ultrastructure characteristic of viable neurosecretory cells; by contrast, the surrounding neurophil showed extensive degeneration. The cultured hypothalamic tissues of the guinea pig that were pulsed with [(3)H]uridine incorporated label into the RNA of neurosecretory neurons, as determined by radioautography and chemical analysis. Furthermore, and most important, these cells retained a complement of hormones and the ability to incorporate (3)H- and (35)S-labeled amino acids into vasopressin, neurophysin, and other polypeptides. This incorporation was inhibited by either puromycin or cycloheximide.
