Localization of serotonin within tanycytes of the rat median eminence

Summary Formaldehyde and glyoxylic acid histochemical methods were employed to examine monoamine fluorescence of the rat median eminence. Tanycytes of the median eminence contained a yellow histofluorescence which was verified with microspectrofluorometry as due to the presence of serotonin. Catecholamine-containing varicosities, arranged in linear profiles throughout the depth of the median eminence, were observed. These linear profiles appeared to follow the contours of serotonin-containing tanycytes. Organculture experiments supported the hypothesis that the serotonin associated with tanycytes is localized within the tanycytes and does not arise from an extrahypothalamic source of nerve terminals. These data provide evidence that a tanycytic catecholamine-indoleamine morphological juxtaposition occurs in a manner reminiscent of that of another circumventricular organ, the pineal.Supported by USPHS Grants NS11642 and AM-19761USPHS Career Development Awardee NS-00259     

Studies on growth hormone secretion IX. Prostaglandins do not act like ionophores

To gain further insight on the mechanism of GH secretion in general and on the stimulation of this process by prostaglandins in particular, we compared the effects of PGE₁ and PGE₂ on hormone release and cyclic nucleotide levels with those of the ionophores A23187 and X537A under a variety of experimental conditions. All these substances (in the presence but not in the absence of calcium) enhanced GH release in incubated rat anterior pituitaries , prostaglandins being considerably more potent than ionophores. However, while PGE₂ caused a dose-dependent rise in pituitary cyclic AMP levels (from doubling at 10⁻⁷ M to a two-hundred fold increase at 10⁻⁵ M), the ionophores had no effect on the concentrations of this nucleotide. Neither PGE₂ nor the ionophores had any measurable effect on cyclic GMP levels. Exposure of tissues to ionophores for 60 minutes rendered them refractory to subsequent stimulation by PGE₁ or to ionophores themselves, whereas preincubation with PGE₁ did not diminish GH responses during a second incubation period. On the other hand, 60-minute preincubation of hemipituitaries in the presence of ionophores (10⁻⁵ M) did not suppress subsequent PGE₁-promoted cyclic AMP accumulation. Metabolic blockers inhibited PGE₂ and A23187-promoted GH-release but failed to suppress GH-response to X537A. Verapamil partially inhibited PGE₂ but not ionophore induced GH secretion. Ionophores particularly X537A, accelerated 45Ca efflux while PGE₁ did not influence this. Electronmicroscopy revealed extensive vacuolization localized chiefly at the Golgi apparatus when tissues were incubated with X537A. PGE₁ and A23187 had no such morphological effect. It is concluded that prostaglandins E and ionophores promote GH secretion by different mechanisms.     

Potential of ultraviolet radiation for control of american cockroach populations

Populations of Periplaneta americana (L.) were exposed for 8–20 week periods in specially designed rooms to 254 nm UV at low intensity (50–115 ergs sec^–1cm^–2), high intensity (160–220 ergs sec^–1cm^–2), or to white light. The rooms contained tables and chairs to simulate occupied space, with food and water placed in positions exposed to UV radiation. General irradiation (where the whole room was exposed to UV) at 115 ergs sec^–1cm^–2 and above was effective in producing high mortality in all stages except 8–10th instar nymphs and adults. Hot-spots irradiation (where UV lamps were placed behind table and chair harborages) produced high mortality only in 1 st-3rd instar nymphs which would result in slower elimination of a population. Crude aggregation pheromone was not successful in holding cockroaches close to radiation sources or substantially increasing mortality under the conditions of the experiments.

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Zusammenfassung Populationen von Periplaneta americana (L.), die hinsichtlich ihrer Alterszusammensetzung (2.–3.; 5–6.; 8.–10. und adultes Stadium) und der Anzahlen in jedem Stadium festgelegt waren, wurden für 8–20 Wochenperioden in speziell dafür entworfenen Räumen einer 254 nm UV-Bestrahlung mit geringer (50–115 erg sec^–1cm^–2) oder hoher (160–220 erg sec^–1cm^–2) Intensität oder weißem Licht (als Kontrolle) ausgesetzt. Die Räume enthielten Tische und Stühle, um bewohnten Raum mit natürlichen Zufluchtsstätten mit Nahrung und Wasser an Stellen, die der UV-Bestrahlung unterlagen, zu simulieren. Ganzraumbestrahlung mit 115 erg sec^–1cm^–2 und darüber erzeugte hohe Mortalität bei 1.–3. und 5.–6.-Larvenstadien, örtliche Bestrahlung (UV-Lampen hinter Tisch- und Stuhl-Zufluchtsstätten) dagegen nur beim 1.–3.-Stadium, was zu einer langsameren Ausrottung einer Population führen würde. Ungereinigtes Aggregationspheromon als Zusatz, um Schaben dicht an die UV-Quellen zu locken und sie hier zu halten, war offenbar unwirksam, da eben die Mortalität nicht signifikant zunahm. Dieses Versagen war in erster Linie auf die Konkurrenz mit der Fülle von natürlichem Pheromon, das von den gewohnten Zufluchtsstätten ausging, zurückzuführen, verbunden mit der dem UV-Licht innewohnenden Abschreckung. Dennoch darf man annehmen, daß UV-Bestrahlung einen bedeutsamen Wert für die Verhinderung eines Populationswachstums (durch Ausschalten junger Larvenstadien) besitzt, besonders dort, wo chemische Bekämpfung aus Gesundheits- und Sicherheitsgründen oder wegen gesetzlichen Einschränkungen nur begrenzt möglich ist.

     

Quinaldine sulphate, a new anaesthetic formulation for tropical marine fishes

Quinaldine sulphate is demonstrated in this study to be a convenient and safe anaesthetic for use with tropical marine fishes. Both onset of anaesthesia and recovery are significantly more rapid than with the parent compound, quinaldine.     

SUBCELLULAR DISTRIBUTION OF A HEAT-STABLE PROTEIN INHIBITOR OF CYCLIC AMP-DEPENDENT PROTEIN KINASE IN RAT BRAIN

Abstract— Cyclic AMP (cAMP)-dependent protein kinase catalyzes the phosphorylation of polypeptidic serine and threonine residues according to the following chemical equation: ATP + protein → phospho-protein + ADP. A heat stable, trypsin labile factor present in brain, skeletal muscle and other tissues inhibits enzymatic phosphorylation of some proteins and enhances that of others. Since brain is one of the richest sources of adenylate cyclase, cAMP, cAMP-dependent protein kinase and the heat stable protein kinase inhibitor and because they may play a role in neurotransmission, an investigation of the subcellular distribution of the heat stable factor in rat brain was undertaken. Although present in the nuclear, mitochondrial and microsomal fractions, the highest activity of protein kinase inhibitor is in the soluble fraction: its activity parallels that of the cytoplasmic enzyme marker, lactate dehydro-genase. The inhibitory activity is also found in the synaptosome or pinched-off nerve ending fraction. Following osmotic lysis of this fraction, about 90% of the factor occurs in the soluble fraction. On the other hand, only 40% of the cAMP-dependent protein kinase is solubilized and 60% remains membrane-bound. Using this membrane-bound protein kinase, phosphorylation of endogenous substrate is unaltered by inhibitor, but phosphorylation of added histone substrate is decreased.     

Diurnal response in endogenous amino acid oxidation of meal-fed rats.

A model has been developed to measure the effects of dietary protein on daily fluctuations in the rate of endogenous amino acid oxidation in meal-fed and starved rats. In addition, N tau-methylhistidine and hydroxyproline were utilized to determine changes in the rate of degradation of myofibrillar and collagen proteins. In rats meal-fed a normal diet of 18% (w/w) casein, a diurnal response was observed in rate of oxidation of radioactive amino acids contained in endogenous labelled body protein, with a nadir 16--20 h and maximum 4--8 h after beginning the feeding. This observation in part may be related to alterations in flux of amino acids from non-hepatic tissues to site of oxidation in liver, as well as alterations in rates of amino acid oxidation after a protein meal. When meal-fed a 70% protein diet, the maximal rates of endogenous amino acid oxidation were significantly increased by 4--8 h after meal-feeding, with no change in fractional rates of degradation of myofibrillar- or collagen-protein breakdown. This could suggest increases in activities of enzymes involved in amino acid oxidation, in rats meal-fed 70% compared with 18% dietary protein. In contrast, meal-feeding of a protein-free diet muted the diurnal response in the rate of oxidation of endogenously labelled amino acids, which correlated with a decrease in the fractional rate of degradation of myofibrillar or collagen protein. Thus dietary protein is apparently responsible for the observed diurnal rhythm rhythms in the rate of amino acid oxidation, whereas carbohydrates tend to mute the response.     

Growth of Iron-Oxidizing Thiobacilli in the Presence of Chalcopyrite and Galena

Iron-oxidizing thiobacilli were adapted to grow on a chalcopyrite and a galena ore concentrate. When grown on the chalcopyrite concentrate, the bacteria exhibited a doubling time of 38.4 ± 2.9 h, with a final cellular protein concentration of 185 μg/ml and solubilization of 10.3 g of copper per liter. When grown on the galena ore concentrate, the generation time was 39.6 ± 2.7 h, with a final cellular protein concentration of 120 μg/ml. Galena was converted to lead salts soluble in 1 M ammonium acetate to a concentration of 20.2 g of lead per liter. X-ray diffraction and refractive-image analysis indicated that the smaller-sized particles were favored in this process. Galena was converted to anglesite, and soluble copper was liberated from chalcopyrite with the concurrent formation of jarosite.