Phylogénie de champignons responsables des charbons des végétaux à partir de l'analyse des séquences ITS

Phylogenetic relationships among fungi belonging to the family of Ustilaginaceae (genera Microbotryum, Sphacelotheca, Ustilago, Sporisorium) are inferred from a parsimony analysis using the ITS sequences of nuclear ribosomal genes. The introduction in the phylogeny of sequences from species of Suillus, Puccinia and Taphrina as outgroup shows the polyphyletism of this family. These results support the division of this taxon into two groups: Ustilaginaceae s. str. formed only by the pathogens of Poaceae, and Microbotryaceae constituted by the pathogens of Dicotyledons. Furthermore, we proposed to extend the host plant spectrum of Ustilaginaceae s. str. to all the Monocotyledons. Several discriminating characteristics are listed to support this distinction.     

Contribution nouvelle à l'étude des ferrobacteriacées

Sans résumé     

Structure granaire,réduction du NADP et photophosphorylation des chloroplastes isolés de feuilles d'orge

Summary Barley chloroplasts (Hordeum vulgare L.) have been isolated in aqueous medium by previously described techniques which preserve the outer plastid membrane in numerous chloroplasts. Thus intact chloroplasts are concentrated in Class I fraction and non intact in Class II fraction. A third type, broken Class I, is obtained by the action of a very dilute buffer solution.The observation of freeze-etched preparations has shown that the main distinctive character between the two classes is not so much the presence or the absence of the outer plastid membrane, as it was assumed, as the state of the thylakoids. In Class I chloroplasts grana are shrunken, in those of Class II, grana are swollen. In both cases the outer membrane may or may not be preserved.The breakage of chloroplasts resulting from treatment with osmotic shocks is due to the dilatation of the extra-lamellar matrix. The swelling of intra-thylakoidal volumes resulting from such a treatment is much less important.It is shown that Class I chloroplasts have a very low NADP reductase activity which is strongly increased after the chloroplasts are broken by osmotic shocks. Such a treatment is without any effect on Class II chloroplasts, which always exhibit a low NADP reductase activity.The situation is rather different in regard to photophosphorylation. It is also lower in Class II than in Class I, but after breakage by osmotic shocks the increase of this activity is weak, and much less significant than the increase observed in NADP reduction. The compression and cohesion of the thylakoids is not required for high photophosphorylation activity with artificial electron acceptors such as PMS. In this case cyclic photophosphorylation is higher in Class II than in Class I.

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Abbreviations ADP, ATP adénosine di et triphosphate - EDTA éthylène diamine trétaacétate - NAD, NADP, NADPH₂ nicotinamide adénine dinucléotide, d° phosphate (formes oxydée et réduite) - PMS phénazine méthosulfate - Pi phosphate inorganique     

Sur quelques propriétés physico-chimiques des protéines séparées des sérums par la méthode à l'acétone

Sans résuméCes diverses études conduisent toutes à cette conclusion que la séparation des protéines effectuée à basse température par la méthode dite à l'acétone de MM.Piettre etVila respecte l'intégrité des molécules protéiques.     

Contribution à la connaissance des Desmidiées du Sud-est de la Province de Québec et de la Gaspésie

Sans résumé     

Cultures de tissus d'insectes a l'aide de sérum de mammifères

Summary The comparative study of cultures of the tissues of the ovary sheath of the female gonad and of the hemocytes of Lepidopterous by means of varying proportions of insect serum and calf serum, has revealed that the serum of mamalians can to a great extent take the place of insect serum. Nevertheless the incorporation of a small amount of insect serum is beneficial to the culture. The principle which is described makes it possible, in particular, to cultivate the tissues of very small insects.      

Etude des migrations verticales journalières du phytoplancton à l'aide d'enceintes placées dans un Rang peu profond

Two enclosures without a bottom were placed in a shallow non-stratified pond. One of these enclosures (B) had a transparent plastic wall and was open at the top. The second enclosure (N) was painted in black and covered over. The vertical distribution and daily migration of Ceratium hirundinella, Trachelomonas spp., Gomphosphaeria naegeliana and Aphanizomenon flos-aquae were studied. Investigations were carried out during a 24 h period both in the pond and inside the two enclosures. Vertical migration was shown by the four algae, even within the water column N. Differences between the behaviour patterns of the different algae are described.

     

Résumés des communications orales et affichées

XVIème Congres de la Societe d’Andrologie de Langue Francaise Issy-Les-Moulineaux 9-11 Décembre 1999

Résumés des communications orales et affichées     

Analyse des courbes de survie clonale obtenues chez des Chlorelles aprés irradiation gamma à divers débits de doses

Résumé Les courbes de survie sont obtenues par irradiation gamma, fractionnée ou non, à débit de dose élevé ou faible. Elles portent sur des Chlorelles à l'état quiescent par rapport au cycle cellulaire (cellules en G₀). Elles s'expliquent en envisageant trois catégories de lésions par irradiation: les lésions létales d'emblée, les lésions sublétales non restaurables et les lésions sublétales restaurables.

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Analysis of clonal survival curves obtained on -irradiated Chlorella cells at several dose rates

Summary The survival curves have been obtained after split or unsplit doses at high or low dose-rate. The living material wasChlorella cells in G₀ stage (non-dividing cells). It is possible to explain these curves by the effects of three types of damage: directly lethal damage, repairable sublethal damage and non-repairable sublethal damage.