Tubular Heads in Bacteriophages from Lactic Streptococci

Tubular bacteriophage heads were observed in the lysate of two phages from Streptococcus lactis obtained from single plaques without mutagenesis. The frequency of appearance of the tubular heads was 2.5 and 16%.     

La 5′-méthoxybilobétine,une biflavone extraite du Ginkgo biloba

A new biflavone, I-5′-methoxybilobetin has been isolated from Ginkgo biloba leaves. ¹H and ¹³C NMR spectral data show that it is a II-4′, I-5, II-5, I-7, II-7-pentahydroxy-I-4′, I-5′-dimethoxy- [I-3′, II-8] biflavone.     

Étude comparée de vibrions de haute mer et de leurs homologues non marins: biochimie,nutrition et taxonomie numérique

Résumé Sept souches ont été isolées d'eau de mer (Atlantique Nord) par 400 m de fond. 17 souches de référence (14 Vibrio et 3 Aeromonas) provenant des collections CIP et NCMB ont été également étudiées. 215 caractères biochimiques et nutritionnels sont définis pour chaque souche et les coefficients de similitude sont calculés sur ordinateur. Le dendrogramme représente l'assemblage des souches par liaisons pondérées.Les sept souches marines sauvages sont des biotypes d'une même espèce de Vibrio. Ces souches sont très semblables à V. marinus et V. noctiluca également isolées de l'eau de mer. Ces 9 germes forment un groupe dont le spectre nutritionnel est beaucoup plus étroit que celui des vibrions pathogènes et de plus, nécessitent une température inférieure à 20° C et une salinité comprise entre 1% et 7% de NaCl. V. anguillarum et V. piscium semblent appartenir à une même espèce; V. proteus et V. metschnikovii sont également très proches l'un de l'autre.

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A comparative study of pelagic Vibrio species and their nonmarine homologous strains: Biochemical and nutritional characters and numerical taxonomy

Summary Seven strains were isolated from deep-sea atlantic seawater (4,000 m). Seventeen reference strains (14 Vibrio and 3 Aeromonas) coming from CIP and NCMB collections were added. 215 biochemical and nutritional features were determinated for each isolate and similarity coefficients were obtained by computer analysis. The dendrogram was obtained by moderate linkage.The seven marine wild strains are biotypes of one species of Vibrio. V. marinus and V. noctiluca are close to these strains; they have also been isolated from seawater. The numerical range of organic compounds utilisable as sole sources of carbon and energy by the seawater group of these bacteria is smaller than that of the pathogenic group of strains. Specific conditions of temperature and salinity are required by the marine bacteria. V. anguillarum and V. piscium seem to be the same species; also V. proteus and V. metschnikovii are grouped relatively together.

     

Staining Sections Coated with Radiographic Emulsion; A Nuclear Fast Red, Indigo-Carmine Sequence

The radioautographs consisting of emulsion-coated sections, after development, fixation and washing, are stained 3 min (uncritical) by an aqueous solution of 5% aluminium sulfate containing 0.1% nuclear fast red, then washed 2-5 min, and stained 5-10 sec by a saturated aqueous solution of picric acid to which 0.25% of indigo-carmine had been added. This technic stains differentially cell nuclei, cytoplasm, muscle fibers, connective tissues and borders of some epithelial cells. It is unnecessary to subject the slides to differentiating solutions.     

A phosphoglucose isomerase gene is involved in the Rag phenotype of the yeast Kluyveromyces lactis

Summary The rag2 mutant of Kluyveromyces lactis cannot grow on glucose when mitochondrial functions are blocked by various mitochondrial inhibitors, suggesting the presence of a defect in the fermentation pathway. The RAG2 gene has been cloned from a K. lactis genomic library by complementation of the rag2 mutation. The amino acid sequence of the RAG2 protein deduced from the nucleotide sequence of the cloned RAG2 gene shows homology to the sequences of known phosphoglucose isomerases (PGI and PHI). In vivo complementation of the pgi1 mutation in Saccharomyces cerevisiae by the cloned RAG2 gene, together with measurements of specific PGI activities and the detection of PGI proteins, confirm that the RAG2 gene of K. lactis codes for the phosphoglucose isomerase enzyme. Complete loss of PGI activity observed when the coding sequence of RAG2 was disrupted leads us to conclude that RAG2 is the only gene that codes for phosphoglucose isomerase in K. lactis. The RAG2 gene of K. lactis is expressed constitutively, independently of the growth substrates (glycolytic or gluconeogenic). Unlike the pgi1 mutants of S. cerevisiae, the K. lactis rag2 mutants can still grow on glucose, however they do not produce ethanol.     

An exported kinase (FIKK4.2) that mediates virulence-associated changes in Plasmodium falciparum-infected red blood cells

Alteration of the adhesive and mechanical properties of red blood cells caused by infection with the malaria parasite Plasmodium falciparum underpin both its survival and extreme pathogenicity. A unique family of parasite putative exported kinases, collectively called FIKK (Phenylalanine (F) – Isoleucine (I) – Lysine (K) – Lysine (K)), has recently been implicated in these pathophysiological processes, however, their precise function in P. falciparum-infected red blood cells or their likely role in malaria pathogenesis remain unknown. Here, for the first time, we demonstrate that one member of the FIKK family, FIKK4.2, can function as an active kinase and is localised in a novel and distinct compartment of the parasite-infected red blood cell which we have called K-dots. Notably, targeted disruption of the gene encoding FIKK4.2 (fikk4.2) dramatically alters the parasite’s ability to modify and remodel the red blood cells in which it multiplies. Specifically, red blood cells infected with fikk4.2 knockout parasites were significantly less rigid and less adhesive when compared with red blood cells infected with normal parasites from which the transgenic clones had been derived, despite expressing similar levels of the major cytoadhesion ligand, PfEMP1, on the red blood cell surface. Notably, these changes were accompanied by dramatically altered knob-structures on infected red blood cells that play a key role in cytoadhesion which is responsible for much of the pathogenesis associated with falciparum malaria. Taken together, our data identifies FIKK4.2 as an important kinase in the pathogenesis of P. falciparum malaria and strengthens the attractiveness of FIKK kinases as targets for the development of novel next-generation anti-malaria drugs.     

Effects of selenium supplementation on thyroid hormone metabolism in phenylketonuria subjects on a phenylalanine restricted diet

Type I 5′-deiodinase was recently characterized as a selenocysteine-containing enzyme in humans and other mammals. Up to now, the effect of selenium (Se) supplementation on thyroid hormone metabolism in humans has only been reported in the very peculiar nutritional environment of Central Africa, where combined severe iodine and Se deficiency occurs. In this study, a group of phenylketonuria subjects with a low selenium status, but a normal iodine intake were supplemented with selenium to investigate changes in their thyroid hormone metabolism. After 3 wk of selenium supplementation (1 μg/kg/d), both the concentrations of the prohormone thyroxine (T4) and the metabolic inactive reverse triiodothyronine (rT3) decreased significantly. Clinically, the phenylketonuria subjects remained euthyroid before and after selenium supplementation. The individual changes of plasma Se and glutathione peroxidase activity were closely associated with individual changes of plasma T4 and rT3.