Influence of biocontrol strain Pseudomonas fluorescens CHA0 and its antibiotic overproducing derivative on the diversity of root colonizing pseudomonads

Non-target effects of biocontrol strains of Pseudomonas on the population of resident pseudomonads should be assessed prior to their large scale application in the environment. The rifampicin resistant bacterium P. fluorescens CHA0-Rif and its antibiotic overproducing derivative CHA0-Rif/pME3424 were introduced into soil microcosms and the population of resident pseudomonads colonizing cucumber roots was investigated after 10 and 52 days. Both CHA0-Rif and CHA0-Rif/pME3424 displaced a part of the resident pseudomonad population after 10 days. To investigate the population structure, utilization of 10 carbon sources and production of two exoenzymes was assessed for 5600 individual pseudomonad isolates and 1700 isolates were subjected to amplified ribosomal DNA restriction analysis of the spacer region (spacer-ARDRA). After 10 days, only the proportion of pseudomonads able to degrade -tryptophan was reduced in treatments inoculated with either biocontrol strain. In parallel the phenotypic diversity was reduced. These effects were only observed 10 days after inoculation, and they were similar for inoculation with CHA0-Rif and CHA0-Rif/pME3424. Changes in the population structure of resident pseudomonads on cucumber roots during plant growth were more pronounced than changes due to the inoculants. The inoculants did not affect the genotypic diversity detected with spacer-ARDRA, but the genotypic fingerprints corresponded only partially to the phenotypic profiles. Overall CHA0-Rif had a small and transient impact on the population of resident pseudomonads and the effect was essentially the same for the genetically engineered derivative CHA0-

Self-similar community structure in a network of human interactions

We propose a procedure for analyzing and characterizing complex networks. We apply this to the social network as constructed from email communications within a medium sized university with about 1700 employees. Email networks provide an accurate and nonintrusive description of the flow of information within human organizations. Our results reveal the self-organization of the network into a state where the distribution of community sizes is self-similar. This suggests that a universal mechanism, responsible for emergence of scaling in other self-organized complex systems, as, for instance, river networks, could also be the underlying driving force in the formation and evolution of social networks.

L'Endimion de Gombauld ([Reprod.])

Collection : French books 1601-1700 ; 67.2

L'amaranthe de Gombauld : pastorale ([Reprod.])

Collection : French books 1601-1700 ; 66.4

Les épigrammes de Gombauld ([Reprod.])

Collection : French books 1601-1700 ; 66.5

Les poésies de Gombauld ([Reprod.])

Collection : French books 1601-1700 ; 66.6

Nouveau traité des arbres fruitiers... par Duhamel Du Monceau. Nouvelle édition... par MM. Veillard, Jaume Saint-Hilaire, Mirbel, Poiret et Loiseleur-Deslongchamps...

Mécénat texte imprimé : Cet ouvrage a été numérisé grâce à Pascal Séguin

Nouveau traité des arbres fruitiers... par Duhamel Du Monceau. Nouvelle édition... par MM. Veillard, Jaume Saint-Hilaire, Mirbel, Poiret et Loiseleur-Deslongchamps...

Mécénat texte imprimé : Cet ouvrage a été numérisé grâce à Pascal Séguin

[6 lettres autographes signées de Jules Barbier à Henri Heugel, 1897]

23 janvier 1897. Au sujet de ses droits d'auteurs. - 26 mars 1897. Demande une avance. - 1er avril 1897. A bien reçu son avance pour le mois de mai et redemande encore de l'argent à son éditeur. - 24 mai 1897. Demande à nouveau de l'argent. - 31 juillet 1897. Conteste une dette de 1700 francs qu'il aurait contractée avec Heugel. Lui demande de vérifier dans ses livres de caisse. - 29 octobre 1897. Papier bordé de noir. L'informe qu'il prononcera quelques mots à l'occasion de l'inauguration du monument d'Antonin Mercié