A physiological dose of estradiol with progesterone affects striatum biogenic amines

The acute effect of estradiol and progesterone on dopamine and serotonin metabolism in rat striatum was studied. One subcutaneous injection of 17 beta-estradiol (300 ng) and progesterone (150 micrograms) into intact male rats increased plasma levels of these steroids, while testosterone, corticosterone, and estrone remained unchanged. Dehydroepiandrosterone, androstane-3 beta, 17 beta-diol and dihydrotestosterone remained undetectably low. Prolactin decreased and androstane-3 alpha, 17 beta-diol, and 17-OH progesterone increased, but less than estradiol and progesterone. Peak levels of striatal dopamine, dihydroxyphenylacetic acid, and homovanillic acid were observed 15-45 min after steroid injection with a return to control values after 45-60 min, while serotonin and 5-hydroxyindoleacetic acid levels were slightly decreased. An injection of estradiol (70 ng) with progesterone (70 micrograms) to ovariectomized female rats left plasma prolactin levels unchanged, while striatum dopamine and serotonin as well as their metabolite concentrations peaked 15-60 min after steroid injection and returned to control values after 45-75 min. To allow for a better comparison of the action of these steroids, the effect of estradiol or progesterone alone and in combination on the brain of ovariectomized rats was compared in the same experiment. A similar increase in metabolites of dopamine levels was observed after these steroids alone or in combination, while dopamine levels were increased only after progesterone alone or in combination with estradiol. An injection of estradiol or progesterone to ovariectomized rats led to peak steroid concentrations at approximately the same time in the brain and plasma. In addition, plasma and brain steroid levels were significantly correlated.(ABSTRACT TRUNCATED AT 250 WORDS)     

Proton-induced grana formation in chloroplasts. Distribution of chlorophyll-protein complexes and Photosystem II photochemistry

Lowering the pH of the incubation medium to pH 5.4 leads to grana formation morphologically similar to that induced by metal cations. The same phenomenon is observed in EDTA-washed chloroplasts, indicating that it is not due in part to electrostatic ‘masking’ by residual cations associated with the membranes. Digitonin fractionation studies have indicated that the distribution of the major chlorophyll-protein complexes between granal and stromal membrane regions is similar at pH 5.4 in the absence of Mg²⁺, and at pH 7.4 in the presence of Mg²⁺. Chlorophyll fluorescence induction studies have indicated that the primary photochemistry of Photosystem II (PS II) is stimulated by lowering the pH to 5.4, just as it is upon metal cation addition at higher pH values. The failure to observe such an increase at pH 5.4 by measuring electron transport to ferricyanide is attributed to a combination of an inhibition by this pH of electron transport at a site after Q reduction and an increase in the number of PS II centres detached from the plastoquinone pool. We conclude that the stacked configuration of chloroplast membranes leads to increased PS II primary photochemistry, which is most simply explained in terms of a redistribution of excitation energy towards PS II.     

Effect of Kainic Acid, Glutamate, and Aspartate on CO2 Production by Goldfish Tectal Slices

For a study of the excitatory effect of kainate, glutamate, and aspartate in the goldfish optic tectum, these substances were tested on the production of CO2 from radioactive glucose in tectal slices incubated in Krebs-Ringer medium for fish. Kainate increased the rate of CO2 production for up to 30 min in a dose-related manner, the effect being maximum at 0.1 mM concentration and decreasing at higher doses. The effect was blocked by ouabain (1 mM) as well as by the substitution of choline for Na+ in the incubation medium. Glutamate and aspartate exerted a less pronounced excitatory effect on CO2 production at higher concentration than kainate. This effect was also abolished by ouabain. Glutamate, added to the medium at a concentration at least 100-fold higher than kainate, partially reversed the increase in CO2 production induced by kainic acid. No similar effect was noticed for aspartate. The supposed glutamate antagonists glutamic acid diethylester (1 mM) and proline (5 mM) did not affect the excitatory action of kainic acid or exert an antagonistic effect towards glutamate. At higher concentration (10 mM) glutamic acid diethylester increased CO2 production, an effect that was, however, ouabain insensitive. Methyltetrahydrofolic acid (1 mM), a substance reported to compete for the kainate receptor, did not inhibit the effect of kainic acid or increase CO2 production.     

Amino acid transport in pig lymphocytes Enhanced activity of transport system asc following mitogenic stimulation

Changes in neutral amino acid transport activity caused by addition of phytohaemagglutinin-P to quiescent peripheral pig lymphocytes have been evaluated by measurements of ¹⁴C-labelled neutral and analogue amino acids under conditions approaching initial entry rates. Utilizing methylaminoisobutyric acid, the best model substrate of System A, we confirmed our previous report (Borghetti, A.F., Kay, J.E. and Wheeler, K.P. (1979) Biochem. J. 182, 27–32) on the absence of this transport system in quiescent cells and its emergence following stimulation. Furthermore, we demonstrated the presence in quiescent cells of an Na⁺-dependent transport system for neutral amino acids that has been characterized as System ASC by several criteria including intolerance to methylaminoisobutyric acid, strict Na⁺-dependence, the property of transtimulation and specificity for pertinent substrates such as alanine, serine, cysteine and threonine. Analysis of the relationship between influx and substrate concentration revealed that two independent saturable components contribute to entry of alanine in quiescent cells: a low affinity ($\text{K}{}_{\mathrm{<mtext>m</mtext>}}\text{= ≈4}\text{mM}$) and a high affinity ($\text{K}{}_{\mathrm{<mtext>m</mtext>}}\text{= ≈0.2}\text{mM}$) component. The high affinity component could be inhibited in a competitive way by serine, cysteine and threonine, but methylaminoisobutyric acid did not change appreciably its constants. The enhanced activity of alanine transport through the ASC system observed in activated cells resulted from a large increase in the capacity ($\text{V}$) of the high affinity component without any substantial change in the apparent affinity constant ($\text{K}{}_{\mathrm{<mtext>m</mtext>}}$).     

Stimulation of poly(dT) transcription by Bacillussubtilis RNA polymerase in the presence of adenosine monophosphate

The rate of synthesis of poly(A) on a ply(dT) template by $\text{Bacillus}\text{subtilis}$ RNA polymerase is a function of ATP concentration and is expressed as a sigmoidal curve. The addition of millimolar concentration of AMP to low concentrations of ATP stimulates synthesis of poly(A) twenty fold and raises the rate of synthesis to the levels obtained at high ATP concentrations. The reaction is completely dependent upon the presence of poly(dT) and requires the complementary mononucleotide. Stimulation of poly(A) synthesis by AMP is more evident with the holoenzyme. Analysis of poly(A) products by acrylamide gels showed that the poly(A) synthesized in the presence of AMP has an higher molecular weight than poly(A) synthesized in the absence of AMP.     

Etude de la dynamique des populations de cilies d'un torrent experimental pendant deux annees

The sampling of Ciliates performed in a little experimental torrent through two years, showed a great similarity of the two annual cycles. This similarity concerns both the species composition as well as the dynamics of the Ciliates populations. The basic species which affect the community structure are as follows: Ctedoctema acanthocrypta, Mesodinium acarus, Cyclidium glaucoma, Cinetochilum margaritaceum, Pleuronema coronatum, Lacrymaria pupula, Aspidisca costata and Holosticha vernalis. The dynamics of the ciliated Protozoa living in this environment seem to be influenced by the speed of the current, the temperature and the amount of dissolved organic matter in the water.

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Etude de la dynamique des populations de cilies d'un torrent experimental pendant deux annees

     

Interrelationship between oxygen consumption,superoxide anion and hydrogen peroxide formation in phagocytosing guinea pig polymorphonuclear leucocytes

The paper presents an experimental procedure for a simultaneous assay of oxygen consumption, O2- release and H2O2 accumulation at a very early stage of the respiratory burst that is induced by phagocytosis in guinea pig polymorphonuclear leucocytes. The main findings are as follows: (a) The oxygen consumption that is measurable does not correspond to all oxygen that is reduced. The relationship between the actual oxygen consumed and the amount that is reduced depends on the fate of the intermediate products O2- and H2O2. (b) O2- is measurable extracellularly by the reduction of cytochrome c. When cytochrome c oxidizes the extracellular O2-, molecular oxygen is formed. This fact is shown by a decrease of oxygen consumption. The molar ratio between the O2- detected and the oxygen given back is 1. (c) The amount of O2- released from the cells accounts for only a small part of oxygen actually reduced. (d) H2O2 is detectable only in the presence of NaN3. In this condition almost all oxygen consumed is recovered in the form of H2O2. The molar ratio O2/H2O2 is near unity. The amount of H2O2 derived from dismutation of O2- released is only an aliquot of the total H2O2 accumulated. Thus, most of H2O2 is derived from intracellular sources. (e) In the absence of inhibitors of H2O2 degrading reactions, no detectable accumulation of peroxide occurs. Under these conditions, the main part of H2O2 formed is degraded in almost equal amount by catalase and myeloperoxidase, while only a small aliquot is degraded by NaN3 insensitive reactions.     

On the fungitoxicity of some new thiocyanatopyrazole derivatives: Electron microscopical study in trichophyton mentagrophytes

Four thiocyanatopyrazole derivatives were synthesized and their fungistatic activity was demonstrated in vitro against a number of dermatophytic fungi. In Trichophyton mentagrophytes, the most active compound induced an unusual increase of the plasma membrane with production of intra and extracytoplasmic complexes, a deterioration of nuclear and mitochondrial membranes and a formation of autophagic-like vacuoles. Plasmolysis, accompanied by an almost complete disorganization of cytoplasmic structures, seemed to be the final event. A possible mechanism of action of the compounds was discussed.Investigation supported by a grant from Consiglio Nazionale delle Ricerche of Italy (Contract No. 7500536).     

Chromosome constitution of in vitro segregated haploid and diploid cells of the mouse

The composition in segregated haploid sets of paternal and maternal chromosomes has been studied in order to verify whether their composition is uniparental of mixed, fixed or variable. Primary cultures where prepared using kidneys from hybrids of strains of Mus musculus in which the parental chromosomes are distinguishable; the maternal set consists of 20 teleocentric chromosomes, the paternal set of 9 metacentric chromosomes, derived by Robertsonian fusion and 2 telocentrics. Applying Seabright's banding technique, an analysis of segregated haploid and diploid cells, which have originated spontaneously through polyploidisation-segregation processes was carried out. It was concluded that the haploid sets have a variable composition of paternal and maternal chromosomes.