Apoptosis-Like Death in Bacteria Induced by HAMLET, a Human Milk Lipid-Protein Complex

Background: Apoptosis is the primary means for eliminating unwanted cells in multicellular organisms in order to preserve tissue homeostasis and function. It is characterized by distinct changes in the morphology of the dying cell that are orchestrated by a series of discrete biochemical events. Although there is evidence of primitive forms of programmed cell death also in prokaryotes, no information is available to suggest that prokaryotic death displays mechanistic similarities to the highly regulated programmed death of eukaryotic cells. In this study we compared the characteristics of tumor and bacterial cell death induced by HAMLET, a human milk complex of alpha-lactalbumin and oleic acid. Methodology/Principal Findings: We show that HAMLET-treated bacteria undergo cell death with mechanistic and morphologic similarities to apoptotic death of tumor cells. In Jurkat cells and Streptococcus pneumoniae death was accompanied by apoptosis-like morphology such as cell shrinkage, DNA condensation, and DNA degradation into high molecular weight fragments of similar sizes, detected by field inverse gel electrophoresis. HAMLET was internalized into tumor cells and associated with mitochondria, causing a rapid depolarization of the mitochondrial membrane and bound to and induced depolarization of the pneumococcal membrane with similar kinetic and magnitude as in mitochondria. Membrane depolarization in both systems required calcium transport, and both tumor cells and bacteria were found to require serine protease activity (but not caspase activity) to execute cell death. Conclusions/Significance: Our results suggest that many of the morphological changes and biochemical responses associated with apoptosis are present in prokaryotes. Identifying the mechanisms of bacterial cell death has the potential to reveal novel targets for future antimicrobial therapy and to further our understanding of core activation mechanisms of cell death in eukaryote cells

Anti‑predatory chemical defences in Antarctic benthic fauna

Antarctic benthic communities are largely structured by predation, which leads to the development of mechanisms of repellence. Among those mechanisms, chemical defences are quite extensive, yet poorly understood. To increase knowledge about the role of chemical defences in the Southern Ocean ecosystems, we assessed the incidence of feeding repellents in sessile and vagile invertebrates from nine phyla: Porifera, Cnidaria, Nemertea, Annelida, Mollusca, Bryozoa, Echinodermata, Hemichordata, and Tunicata (Ascidiacea). Samples were collected at depths of 120–789 m in the eastern Weddell Sea and Bouvet Island, and at depths ranging 0–100 m in the South Shetland Islands. When possible, specimens were dissected to study anatomical allocation of repellents. The common, eurybathic sea star Odontaster validus was chosen to perform feeding repellence bioassays, using diethyl ether (lipophilic) and butanol (hydrophilic) extracts from these samples. Among the 75 species tested, 52 % were studied for the first time for anti-predatory properties. Results provide further evidence of the prevalence of defensive metabolites in Antarctic organisms, with 47 % of the species exhibiting significant repellence within their lipophilic extracts. They also suggest a wider use of nonpolar defensive chemicals. Sessile taxa displayed highest repellence activities, with ascidians, cnidarians, and sponges being the most chemically protected. Overall, the present study indicates that natural products by mediating trophic interactions between prey and their potential predators play an important role in structuring Antarctic benthic ecosystems.Versión del editor2,011

SOSORT consensus paper: school screening for scoliosis. Where are we today?

This report is the SOSORT Consensus Paper on School Screening for Scoliosis discussed at the 4th International Conference on Conservative Management of Spinal Deformities, presented by SOSORT, on May 2007. The objectives were numerous, 1) the inclusion of the existing information on the issue, 2) the analysis and discussion of the responses by the meeting attendees to the twenty six questions of the questionnaire, 3) the impact of screening on frequency of surgical treatment and of its discontinuation, 4) the reasons why these programs must be continued, 5) the evolving aim of School Screening for Scoliosis and 6) recommendations for improvement of the procedure