Phage inducible islands in the gram-positive cocci

The SaPIs are a cohesive subfamily of extremely common phage-inducible chromosomal islands (PICIs) that reside quiescently at specific att sites in the staphylococcal chromosome and are induced by helper phages to excise and replicate. They are usually packaged in small capsids composed of phage virion proteins, giving rise to very high transfer frequencies, which they enhance by interfering with helper phage reproduction. As the SaPIs represent a highly successful biological strategy, with many natural Staphylococcus aureus strains containing two or more, we assumed that similar elements would be widespread in the Gram-positive cocci. On the basis of resemblance to the paradigmatic SaPI genome, we have readily identified large cohesive families of similar elements in the lactococci and pneumococci/streptococci plus a few such elements in Enterococcus faecalis. Based on extensive ortholog analyses, we found that the PICI elements in the four different genera all represent distinct but parallel lineages, suggesting that they represent convergent evolution towards a highly successful lifestyle. We have characterized in depth the enterococcal element, EfCIV583, and have shown that it very closely resembles the SaPIs in functionality as well as in genome organization, setting the stage for expansion of the study of elements of this type. In summary, our findings greatly broaden the PICI family to include elements from at least three genera of cocci

Phage-inducible chromosomal islands are ubiquitous within the bacterial universe

Phage-inducible chromosomal islands (PICIs) are a recently discovered family of pathogenicity islands that contribute substantively to horizontal gene transfer, host adaptation and virulence in Gram-positive cocci. Here we report that similar elements also occur widely in Gram-negative bacteria. As with the PICIs from Gram-positive cocci, their uniqueness is defined by a constellation of features: unique and specific attachment sites, exclusive PICI genes, a phage-dependent mechanism of induction, conserved replication origin organization, convergent mechanisms of phage interference, and specific packaging of PICI DNA into phage-like infectious particles, resulting in very high transfer frequencies. We suggest that the PICIs represent two or more distinct lineages, have spread widely throughout the bacterial world, and have diverged much more slowly than their host organisms or their prophage cousins. Overall, these findings represent the discovery of a universal class of mobile genetic elements

Accountability AA1000 Series Of Standards

Uno de los principales estudios del Proyecto al que se vincula la presente obra es el análisis de los estándares propios a los que se adhieren las entidades financieras para probar que son socialmente responsable, y uno de los estándares es el que se analiza en este artículo, las normas y principios AccountAbility. Se realiza un profundo estudio del origen de la Norma AA1000, así como del proceso de desarrollo de la Norma y de la evolución de los Principios de AccountAbility. Se indican cuales son los propósitos, características y ventajas de la Norma AA1000. Asimismo, una parte de la aportación se encarga del estudio del ámbito de aplicación y estructura de la Norma AA1000, analizando el Estándar de aseguramiento y explicando que debemos entender por Norma de grupos de interés. También se estudian los Principios de AccountAbility AA1000: el principio de inclusividad; el principio de relevancia; el principio de capacidad de respuesta; y el principio de impacto. Se indica cómo pueden las empresas adherirse a estas normas y principios, y qué compromisos supone esa adhesión, así como cuáles son los mecanismos de control que se utilizan en cada uno de los principios