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.     

Biogenesis of linear O-alkylfuranocoumarins: A new pathway involving 5-hydroxymarmesin

adioactivity from [³H] 5-hydroxymarmesin was incorporated into 5-methoxypsoralen by administration to leaves of Ficus carica and cut ends of Ruta graveolens. No other furanocoumarins were labelled. Trapping experiments, in which [³H]marmesin together with 5-hydroxymarmesin was administered to fig leaves and to cut ends of rue, provided good evidence that 5-hydroxymarmesin is formed by hydroxylation of marmesin. These results, together with those obtained previously with 8-hydroxymarmesin demonstrate that, in addition to the pathway which involves the hydroxylation of psoralen, the O-alkylfuranocoumarins are also formed by a pathway which involves the hydroxylation of marmesin.     

Directional Preferences in the Autumn Migration of the Red Admiral (Vanessa atalanta)

The paper describes the orientation performance of the red admiral in the course of its migratory movements through the Italian peninsula, a region where systematic studies of this butterfly species have not been carried out before. Our results show that red admirals exhibit seasonal bidirectional migratory movements between breeding and wintering grounds. Orientation performances, directional preferences in the autumn and spring were recorded and discussed; in addition, we have documented a progressive eastward shift of the main flight direction, during the autumn migratory season, which appears to be related to air temperature. Speculative explanations for this shift of flight direction, which has never been recorded before, are given.