Characterization of atypical Listeria innocua isolated from swine slaughterhouses and meat markets

Atypical Listeria innocua strains presenting phenotypic characteristics similar to those of Listeria monocyto genes were recently isolated from food and the environment. These isolates also tested positive for virulence genes specific to L. monocytogenes. Here we report the isolation of atypical hemolytic L. innocua strains from the environment of pork processing plants in Brazil. The strains were positive for L. monocytogenes virulence genes hly, inlA and inlB by PCR and presented genotypic similarities with human isolates of L. monocytogenes via the AFLP technique using HindIII single enzyme protocol. Phenotypic and genotypic similarities suggest that these atypical L. innocua may be pathogenic strains. (C) 2012 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

Shifts in phylogenetic diversity of archaeal communities in mangrove sediments at different sites and depths in southeastern Brazil

This study focused on the structure and composition of archaeal communities in sediments of tropical mangroves in order to obtain sufficient insight into two Brazilian sites from different locations (one pristine and another located in an urban area) and at different depth levels from the surface. Terminal restriction fragment length polymorphism (T-RFLP) of PCR-amplified 16S rRNA gene fragments was used to scan the archaeal community structure, and 16S rRNA gene clone libraries were used to determine the community composition. Redundancy analysis of T-RFLP patterns revealed differences in archaeal community structure according to location, depth and soil attributes. Parameters such as pH, organic matter, potassium and magnesium presented significant correlation with general community structure. Furthermore, phylogenetic analysis revealed a community composition distributed differently according to depth where, in shallow samples, 74.3% of sequences were affiliated with Euryarchaeota and 25.7% were shared between Crenarchaeota and Thaumarchaeota, while for the deeper samples, 24.3% of the sequences were affiliated with Euryarchaeota and 75.7% with Crenarchaeota and Thaumarchaeota. Archaeal diversity measurements based on 16S rRNA gene clone libraries decreased with increasing depth and there was a greater difference between depths (<18% of sequences shared) than sites (>25% of sequences shared). Taken together, our findings indicate that mangrove ecosystems support a diverse archaeal community; it might possibly be involved in nutrient cycles and are affected by sediment properties, depth and distinct locations. (C) 2012 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

The nature of extremely red galaxies in the local universe

We investigate the nature of extremely red galaxies (ERGs), objects whose colours are redder than those found in the red sequence present in colour–magnitude diagrams of galaxies. We selected from the Sloan Digital Sky Survey Data Release 7 a volume-limited sample of such galaxies in the redshift interval 0.010 < z < 0.030, brighter than Mr = −17.8 (magnitudes dereddened, corrected for the Milky Way extinction) and with (g − r) colours larger than those of galaxies in the red sequence. This sample contains 416 ERGs, which were classified visually. Our classification was cross-checked with other classifications available in the literature. We found from our visual classification that the majority of objects in our sample are edge-on spirals (73 per cent). Other spirals correspond to 13 per cent, whereas elliptical galaxies comprise only 11 per cent of the objects. After comparing the morphological mix and the distributions of Hα/Hβ and axial ratios of ERGs and objects in the red sequence, we suggest that dust, more than stellar population effects, is the driver of the red colours found in these extremely red galaxies.