The cyanobacterial cell division factor Ftn6 contains an N-terminal DnaD-like domain

<p>Abstract</p> <p>Background</p> <p>DNA replication and cell cycle as well as their relationship have been extensively studied in the two model organisms <it>E. coli </it>and <it>B. subtilis</it>. By contrast, little is known about these processes in cyanobacteria, even though they are crucial to the biosphere, in utilizing solar energy to renew the oxygenic atmosphere and in producing the biomass for the food chain. Recent studies have allowed the identification of several cell division factors that are specifics to cyanobacteria. Among them, Ftn6 has been proposed to function in the recruitment of the crucial FtsZ proteins to the septum or the subsequent Z-ring assembly and possibly in chromosome segregation.</p> <p>Results</p> <p>In this study, we identified an as yet undescribed domain located in the conserved N-terminal region of Ftn6. This 77 amino-acids-long domain, designated here as FND (Ftn6 N-Terminal Domain), exhibits striking sequence and structural similarities with the DNA-interacting module, listed in the PFAM database as the DnaD-like domain (pfam04271). We took advantage of the sequence similarities between FND and the DnaD-like domains to construct a homology 3D-model of the Ftn6 FND domain from the model cyanobacterium <it>Synechocystis </it>PCC6803. Mapping of the conserved residues exposed onto the FND surface allowed us to identify a highly conserved area that could be engaged in Ftn6-specific interactions.</p> <p>Conclusion</p> <p>Overall, similarities between FND and DnaD-like domains as well as previously reported observations on Ftn6 suggest that FND may function as a DNA-interacting module thereby providing an as yet missing link between DNA replication and cell division in cyanobacteria. Consistently, we also showed that Ftn6 is involved in tolerance to DNA damages generated by UV rays.</p

Une équation non linéaire intervenant en solidification

résum

Effects of Insecticide and Tolerant Alfalfa Cultivars on Potato Leafhopper (\u3cem\u3eEmpoasca fabae\u3c/em\u3e) Populations and Forage Yields in Quebec (Canada)

The potato leafhopper [PLH, Empoasca fabae (Harris)], which affects several crops including alfalfa (Medicago sativa L.), is a recurrent problem in several regions of Quebec. The objective was to evaluate alfalfa management tools in order to reduce yield losses caused by this pest. An experiment was conducted at two sites in Quebec over three field seasons to evaluate the impact of insecticide applications and the use of PLHtolerant cultivars on forage yield and PLH populations. Foliar insecticide applications in the seeding year reduced PLH populations but generally failed to impact alfalfa yields compared to untreated alfalfa. However, in one experiment at one site, applications done in the seeding year resulted in increased first-cut alfalfa yields in the post-seeding year compared to untreated alfalfa, even if PLH populations were low. Differences in yields between PLH-tolerant and PLH-susceptible cultivars were minimal in the seeding and post-seeding years regardless of the PLH population levels. However, two PLH-tolerant cultivars produced lower yields compared to other cultivars in the post-seeding year at one site. Preliminary results suggest that foliar insecticide applications could be a more effective way to reduce PLH populations than PLH-tolerant cultivars. However, more data will be required to confirm these results and determine the impact of these management tools on alfalfa yields

Agressivité du Simulium du complexe ornatum (Diptera, Simuliidae) en Catalogne (Espagne). Premiere mention

A l'heure actuelle, en Espagne, même si des Simulies sont incriminées chez l'homme, dans des lésions dues à des insectes hématophages, le lien direct entre ces piqûres et une espèce donnee de Simulie n'avait pas encore été éetabli pour ce pays. Une invasion récente (1993) de ces insectes dans la région de l'Alt Penedès, au nord-est de la province de Tarragone, permet aujourd'hui de combler cette lacune