פרסומים

Finding optimal markers for microorganisms important in the medical, agricultural, environmental or ecological fields is of great importance. Thousands of complete microbial genomes now available allow us, for the first time, to exhaustively identify marker proteins for groups of microbial organisms. In this work, we model the biological task as the well-known mathematical “hitting set” problem, solving it based on both greedy and randomized approximation algorithms. We identify unique markers for 17 phenotypic and taxonomic microbial groups, including proteins related to the nitrite reductase enzyme as markers for the non-anammox nitrifying bacteria group, and two transcription regulation proteins, nusG and yhiF, as markers for the Archaea and Escherichia/Shigella taxonomic groups, respectively. Additionally, we identify marker proteins for three subtypes of pathogenic E. coli, which previously had no known optimal markers. Practically, depending on the completeness of the database this algorithm can be used for identification of marker genes for any microbial group, these marker genes may be prime candidates for the understanding of the genetic basis of the group's phenotype or to help discover novel functions which are uniquely shared among a group of microbes. We show that our method is both theoretically and practically efficient, while establishing an upper bound on its time complexity and approximation ratio; thus, it promises to remain efficient and permit the identification of marker proteins that are specific to phenotypic or taxonomic groups, even as more and more bacterial genomes are being sequenced.

2-Aminoacetophneone (2-AA) is a volatile molecule produced in high amounts by the opportunistic pathogen Pseudomonas aeruginosa. We have previously shown that 2-AA activates the quorum sensing (QS) LuxR receptor of Aliivibrio fischeri. In the present study we were able to improve LuxR's affinity and detection limit for 2-AA by genetic modification of three amino acids within the binding pocket of the receptor. Expression of the modified LuxR receptor in a luminescent bacterial biosensor provided an efficient detection assay of 2-AA in clinical P. aeruginosa strains isolated from blood and lung infections, as well as in phlegm samples obtained from subjects suffering from lung infections.

Waterborne pathogens are a major health threat and must be eliminated to guarantee safe usage of water for potable purposes. For this purpose, a new carbon-based nanomaterial composed of single-walled carbon nanotubes (SWCNTs) and iron oxides was constructed for bacterial inactivation. Owing to its magnetic properties, the SWCNT–iron oxide nanocomposite may serve as a reusable antimicrobial agent. The nanocomposite material exhibited high antimicrobial activity against Escherichia coli. Successful reuse of the nanocomposite material was achieved by washing with calcium chloride and distilled water, which restored its performance for several successive cycles. To investigate the cytotoxicity mechanisms of the nanocomposite material, we exposed it to single-gene knockout mutant strains of E. coli. Mutants bearing shorter lipopolysaccharide (LPS) layers in the outer membrane (ΔrfaC and ΔrfaG) demonstrated an increased sensitivity in comparison to the wildtype strain, exemplified in enhanced removal by the nanocomposite material. This finding suggests that the LPS acts as a protective shield against the nanocomposite material. Inactivation of mutants impaired in specific oxidative stress defense mechanisms (ΔsodA, ΔkatG and ΔsoxS) emphasized that oxidative stress plays a significant role in the inactivation mechanism of the nanocomposite. This study sheds light on the mechanisms of bacterial inactivation by carbon-based nanomaterials and advances their potential implementation for water disinfection.

Waterborne pathogens are a major health threat and must be eliminated to guarantee safe usage of water for potable purposes. For this purpose, a new carbon-based nanomaterial composed of single-walled carbon nanotubes (SWCNTs) and iron oxides was constructed for bacterial inactivation. Owing to its magnetic properties, the SWCNT–iron oxide nanocomposite may serve as a reusable antimicrobial agent. The nanocomposite material exhibited high antimicrobial activity against Escherichia coli. Successful reuse of the nanocomposite material was achieved by washing with calcium chloride and distilled water, which restored its performance for several successive cycles. To investigate the cytotoxicity mechanisms of the nanocomposite material, we exposed it to single-gene knockout mutant strains of E. coli. Mutants bearing shorter lipopolysaccharide (LPS) layers in the outer membrane (ΔrfaC and ΔrfaG) demonstrated an increased sensitivity in comparison to the wildtype strain, exemplified in enhanced removal by the nanocomposite material. This finding suggests that the LPS acts as a protective shield against the nanocomposite material. Inactivation of mutants impaired in specific oxidative stress defense mechanisms (ΔsodA, ΔkatG and ΔsoxS) emphasized that oxidative stress plays a significant role in the inactivation mechanism of the nanocomposite. This study sheds light on the mechanisms of bacterial inactivation by carbon-based nanomaterials and advances their potential implementation for water disinfection.

 The role of bacteriolysis in the pathophysiology of microbial infections dates back to 1893 whenBuchner and Pfeiffer reported for the first time the lysis of bacteria by immune serum and relatedthis phenomenon to the immune response. Later on, basic anti-microbial peptides and certainbeta-lactam antibiotics have been shown not only to kill microorganisms but also to induce bacteriolysisand the release of cell-wall components.In 2009, a novel paradigm was offered suggesting that the main cause of death in sepsis is dueto the exclusive release from activated human phagocytic neutrophils (PMNs) traps adheringupon endothelial cells of highly toxic nuclear histone. Since activated PMNs also release a plethoraof pro-inflammatory agonists, it stands to reason that these may act in synergy with histoneto damage cells. Since certain beta lactam antibiotics may induce bacteriolysis, it is questionedwhether these may aggravate sepsis patient’s condition. Enigmatically, since the term bacteriolysisand its possible involvement in sepsis is hardly ever mentioned in the extensive clinicalarticles and reviews dealing with critical care, we hereby aim to refresh the concept of bacteriolysisand its possible role in the pathogenesis of post infectious sequelae. 

This article presents a study that examined beliefs about violent husbands and about helping battered women among Palestinian women living in Israel from the perspective of patriarchal ideology. A convenience sample of 701 married women was obtained, and a self-report questionnaire was administered. The findings reveal that the majority of participants held violent husbands accountable for their behavior; however, the majority of them did not support punishing violent husbands through formal agencies (i.e., the police) or through informal social institutions (i.e., the family). In addition, contrary to expectations, the majority of women perceived wife beating as a social problem rather than as a private one that should be dealt with within the family. Regression and multiple regression analysis revealed that women’s endorsement of patriarchal ideology was found to influence all three above-mentioned beliefs about violent husbands and battered women, over and above the amount of variance in each of these beliefs that could be attributed to the women’s sociodemographic characteristics. The limitations of the study and its implications for future research are discussed.

How does the European Union integrate new values into the text of its treaties? A growing body of literature indicates that, in the past three decades, new norms and values have entered the EU's discourse, resulting in what is usually termed ‘normative power Europe’. Yet the research and knowledge to‐date about the EU's discursive assimilation of new values and norms is surprisingly poor. As any institutional change, such integration has the potential to undermine the coherence of the EU's identity and thus also its objective to ‘speak with one voice’. This article explores the EU's discursive management of the continuity‐versus‐change imperative by analysing the integration of new values into the text of its treaties. This issue is addressed based on a quantitative content analysis on the full texts of European founding treaties between the 1950s and 2009. Findings show that the distribution of the EU's values in the text is not uniform: while the language of market economy and democracy is pervasive, the values of peace, European identity, rights and social justice are mentioned less frequently and in restricted linguistic environments. To account for the differences in the integration of values into the EU's treaty discourse, the article develops the notion of a discursive mechanism of differentiated value integration (MDVI). This rationale echoes the logic of differentiation in policy implementation employed by the EU. It is claimed here that, applied in the European discursive arena, MDVI allows radically different readings of the same text. This helps the EU to maintain a coherent value identity while at the same time enabling change.