La dissertation philosophique est un manuel qui traduit la nécessité de la maîtrise de la méthodologie et répond aux attentes des apprenants par rapport à cet exercice qu'est la dissertation. Il se présente aux yeux de l'auteur, le Dr Salif Coly, comme un moyen de partager avec les élèves, les étudiants, les enseignants et les intellectuels férus de philosophie un certain nombre de réflexions sur la dissertation philosophique. Au-delà des conseils pour éviter certains pièges, l'auteur passe en revue (...) les points essentiels de la dissertation philosophique et procède à une petite révision du programme à travers quelques dissertations complètes. (shrink)

Comment philosopher en classe de terminale? Réflexions sur le commentaire de textes est un manuel qui traduit la nécessité de la maîtrise de la méthodologie dans l'entreprise philosophique. Il se présente aux yeux de l'auteur, le Dr Salif Coly, comme un moyen de partager avec les élèves, les étudiants, les enseignants et les intellectuels férus de philosophie un certain nombre de réflexions sur la méthodologie du commentaire de texte philosophique. C'est donc un manuel de méthodologie entièrement consacré au (...) commentaire. Au-delà des conseils pour éviter certains pièges, l'auteur passe en revue les points essentiels du commentaire et procède à une analyse approfondie de certaines parties du programme à travers une étude rigoureuse de quelques textes. (shrink)

This essay situates Gentile in the debate over the meaning and value of 'modernity' as interpreted by post-War commentators such as Hannah Arendt, Jürgen Habermas and Leo Strauss. Coli shows how Gentile drew upon his predecessors as he developed his actual idealist conception of the relation between thinking, the thinker and the world. Gentile's response to themulti-faceted problem of modernity combines reactionary and progressive elements: the central threads of western culture, he believes, can and should be retained, though updated, refined (...) and reconfigured to rid them of the untenable falsehoods inwhich the old traditions, with their 'methods of transcendence', had left them tangled. (shrink)

O presente artigo aborda alguns textos fundamentais de Vilém Flusser adotando como eixo central a comparação entre o funcionamento das sociedades póshistóricas e o mecanismo da “caixa-preta”, o que permite articular questões específicas dos códigos de comunicação e seus produtos com questões que tratam das consequências das tecno-imagens para o funcionamento das sociedades caracterizadas por Flusser como sociedades de massa ou pós-históricas.

Conhecido como último assistente e mais importante colaborador de Husserl, Eugen Fink foi uma figura decisiva no desenvolvimento final da fenomenologia husserlianas. Mas muito ainda se discute se sua obra posterior à morte de Husserl poderia ou não ser considerada um projeto propriamente fenomenológico. A hipótese deste trabalho é de que o pensamento que Fink desenvolve após a Segunda Guerra pode ser entendida como uma fenomenologia que todavia se volta ao um conceito radicalmente distinto de ‘fenômeno’. Essa radicalidade, por sua (...) vez, se deixa compreender à luz de um projeto fundamental, que caracterizo como contrametafísica. (shrink)

While avoiding taking part in the discussion of whether Fink’s philosophy should or not be considered from two different moments, the intention of the present contribution is to follow the track given by an evident readjustment in the interpretation of Hegel proposed by Fink in two different moments of his intellectual production. The thematic frame concerning his interpretation of Hegel privileges the concepts of absolute and identity, in order to show how they were articulated in two different ways throughout the (...) development of what we here refer to as Fink’s philosophical project. (shrink)

The central focus of this research is the fast and crucial impact of the COVID-19 pandemic, and its exceptionally serious consequences in terms of healthcare, state intervention and impositions, radical changes in people’s life, on a crucial psychological, relational, and political construct: trust. In this survey, addressed to 4260 Italian citizens, we tried to analyze and measure such impact, focusing on various aspects of trust. This attention to multiple dimensions of trust constitutes the key conceptual advantage of this research, since (...) trust is a complex and layered construct, with its own internal dynamics. In particular, the analysis focuses on how citizens attribute trust to Public Authorities, in relation to the management of the health crisis: with regard to the measures and guidelines adopted, the purposes pursued, the motivations that determine them, their capacity for involvement and their effectiveness for the containment of the virus itself. A pandemic creates a bilateral need for trust, both in Public Authorities (they have to rely on citizens’ compliance, and must try to promote and maintain their trust in order to be effective), and in citizens, since they need to feel that somebody can do something, can (has the power) to protect them, to act at the needed collective level. We are interested to explore how this need for trust affects the attributional process, regarding both attitudes and the corresponding decisions and actions. The most striking result of this survey is the very high level of institutional trust expressed by respondents: 75% of them trust Italian public authorities to be able to deal with the COVID-19 emergency. This is in sharp contrast with the relatively low levels of institutional trust characteristic of Italy, both historically and in recent surveys. Moreover, the survey allowed to discriminate several potential predictors for trust, thus emphasizing factors that, during this crisis, are exhibiting an anomalous impact on trust. (shrink)

Focusing on the new theories of human motivation that emerged during the transition from feudalism to the modern period, this is the first book of new essays on the relationship between politics and the passions from Machiavelli to Bentham. Contributors address the crisis of moral and philosophical discourse in the early modern period; the necessity of inventing a new way of describing the relation between reflection and action, and private and public selves; the disciplinary regulation of the body; and the (...) ideological constitution of identity. The collection as a whole asks whether a discourse of the passions might provide a critical perspective on the politics of subjectivity. Whatever their specific approach to the question of ideology, all the essays reconsider the legacy of the passions in modern political theory and the importance of the history of politics and the passions for modern political debates. Contributors, in addition to the editors, are Nancy Armstrong, Judith Butler, Riccardo Caporali, Howard Caygill, Patrick Coleman, Frances Ferguson, John Guillory, Timothy Hampton, John P. McCormick, and Leonard Tennenhouse. (shrink)

The hemolysin toxin (HlyA) is secreted across both the cytoplasmic and outer membranes of pathogenic Escherichia coli and forms membrane pores in cells of the host immune system, causing cell dysfunction and death. The processes underlying the interaction of HlyA with the bacterial and mammalian cell membranes are remarkable. Secretion of HlyA occurs without a periplasmic intermediate and is directed by an uncleaved C‐terminal targetting signal and the HlyB and HlyD translocator proteins, the former being a member of a transporter (...) superfamily central to import and export of a wide range of substrates by prokaryotic and eukaryotic cells. The separate process by which HlyA is targetted to mammalian cell membranes is dependent upon fatty acylation of a non‐toxic precursor, proHlyA. This is achieved by a novel mechanism directed by the activator protein HlyC, which binds to an internal proHlyA recognition sequence and provides specificity for the transfer of fatty acid from cellular acyl carrier protein. (shrink)

A first year graduate student, Ann Dee Margulies, changed my research career in 1962 by challenging me to direct her in the isolation of recombination‐deficient mutants of Escherichia coli K‐12. She succeeded in isolating two mutants, which conjugated with donor strains and received the donor DNA, but could not recombine that DNA with their own chromosomes. Ann Dee showed that both mutants were much more sensitive to UV radiation than was the wild type. Furthermore, she showed that one of these (...) mutants carried a single mutation affecting both recombination and resistance. This work, published in 1965, was the first demonstration of the recA gene of E. coli. Subsequent work led to the discovery of many more recombination genes, the phenomenon of post replication‐recombination repair, the invention of the SOS hypothesis and the discovery of genes encoding proteins with similar primary structure and function in all major groups of organisms. This article honors the memory of Ann Dee. (shrink)

This article concerns the elaboration of epigenetic models for differentiation. I discuss how results and conclusions arising from studies of prokaryotes were extrapolated to explain differentiation during metazoan development. In this respect, I focus on the presentation of a multi-stable biochemical model by Delbrück in 1949, and on a series of works dealing with enzyme adaptation in Escherichia coli that culminated in Jacob and Monod's operon model. These influential contributions are discussed in the context of debates on nuclear versus cytoplasmic (...) heredity, on the regulation of gene expression, as well as on the mechanisms at the basis of cell differentiation. (shrink)

Single‐stranded DNA binding proteins have been known for some time to be crucial in many DNA metabolic reactions in both prokaryotes and eukaryotes. Despite a wealth of studies on these proteins we still do not understand their biochemical mechanism of action. Recent studies of the Escherichia coli single stranded DNA binding protein (SSB) are beginning to provide some insight into how this and similar proteins might function.

Upon first reading, the beginning of Chapter 2 of Difference and Repetition, with its talk of ―contemplative souls‖ and ―larval subjects,‖ seems something of a bizarre biological panpsychism. Actually it does defend a sort of biological panpsychism, but by defining the kind of psyche Deleuze is talking about, I‘ll show here how we can remove the bizarreness from that concept. First, I will sketch Deleuze‘s treatment of ―larval subjects,‖ then show how Deleuze‘s discourse can be articulated with Evan Thompson‘s biologically (...) based intervention into cognitive science, the ―mind in life‖ or ―enaction‖ position. Then I will then show how each in turn fits with contemporary biological work on E. coli chemotaxis (movement in response to changes in environment). (shrink)

Proteinaceous stalks produced by Gram‐negative bacteria are often used to adhere to environmental surfaces. Among them, chaperone‐usher (CU) fimbriae adhesins, related to prototypical type 1 fimbriae, interact in highly specific ways with different ligands at different stages of bacterial infection or surface colonisation. Recent analyses revealed a large number of potential and often “cryptic” CU fimbriae homologues in the genome of commensal and pathogenic Escherichia coli and closely related bacteria. We propose that CU fimbriae form a yet unexplored arsenal of (...) lectins, carbohydrate‐binding proteins involved in various aspects of bacterial surface adhesion and tissue tropism. Combined efforts of molecular and structural biologists will be required to unravel the biological contribution of the bacterial lectome, however, current progress has already opened up new perspectives in the design of novel anti‐infective strategies. (shrink)

If rapid growth (rap) mutants of Escherichia coli could be obtained, these might prove a valuable contribution to fields as diverse as growth rate control, biotechnology and the regulation of the bacterial cell cycle. To obtain rap mutants, a dnaQ mutator strain was grown for four and a half days continuously in batch culture. At the end of the selection period, there was no significant change in growth rate. This result means that selecting rap mutants may require an alternative strategy (...) and a number of such alternatives are discussed. (shrink)

The genes involved in methionine biosynthesis are scattered throughout the Escherichia coli chromosome and are controlled in a similar but not coordinated manner. The product of the metJ gene and S‐adenosylmethionine are involved in the repression of this ‘regulon’.

During the process of E. coli nucleotide excision repair, DNA damage recognition and processing are achieved by the action of the uvrA, uvrB, and uvrC gene products. The availability of highly purified proteins has lead to a detailed molecular description of E. coli nucleotide excision repair that serves as a model for similar processes in eukaryotes. An interesting aspect of this repair system is the protein complex's ability to work on a vast array of DNA lesions that differ widely in (...) their chemical composition and molecular architecture. Here we propose a model for damage recognition in which the UvrB protein serves as the component that confers enhanced specificity to a preincision complex. We hypothesize that one major determinant for the formation of a stable preincision complex appears to be the disruption of base stacking interactions by DNA lesions. (shrink)

Evolutionary theory assumed that mutations occur constantly, gradually, and randomly over time. This formulation from the “modern synthesis” of the 1930s was embraced decades before molecular understanding of genes or mutations. Since then, our labs and others have elucidated mutation mechanisms activated by stress responses. Stress‐induced mutation mechanisms produce mutations, potentially accelerating evolution, specifically when cells are maladapted to their environment, that is, when they are stressed. The mechanisms of stress‐induced mutation that are being revealed experimentally in laboratory settings provide (...) compelling models for mutagenesis that propels pathogen–host adaptation, antibiotic resistance, cancer progression and resistance, and perhaps much of evolution generally. We discuss double‐strand‐break‐dependent stress‐induced mutation in Escherichia coli. Recent results illustrate how a stress response activates mutagenesis and demonstrate this mechanism's generality and importance to spontaneous mutation. New data also suggest a possible harmony between previous, apparently opposed, models for the molecular mechanism. They additionally strengthen the case for anti‐evolvability therapeutics for infectious disease and cancer. (shrink)

Evolution has shaped all living organisms on Earth, although many details of this process are shrouded in time. However, it is possible to see, with one's own eyes, evolution as it happens by performing experiments in defined laboratory conditions with microbes that have suitably fast generations. The longest‐running microbial evolution experiment was started in 1988, at which time twelve populations were founded by the same strain ofEscherichia coli. Since then, the populations have been serially propagated and have evolved for tens (...) of thousands of generations in the same environment. The populations show numerous parallel phenotypic changes, and such parallelism is a hallmark of adaptive evolution. Many genetic targets of natural selection have been identified, revealing a high level of genetic parallelism as well. Beneficial mutations affect all levels of gene regulation in the cells including individual genes and operons all the way to global regulatory networks. Of particular interest, two highly interconnected networks—governing DNA superhelicity and the stringent response—have been demonstrated to be deeply involved in the phenotypic and genetic adaptation of these experimental populations. BioEssays 29:846–860, 2007. © 2007 Wiley Periodicals, Inc. (shrink)

After the completion of RecA protein‐mediated recombinational repair of daughter‐strand gaps in E. coli, participating chromosomes are held together by Holliday junctions. Until recently, it was not known how the cell disengages the connected chromosomes. Accumulating genetic data suggested that the product of the ruv locus participates in recombinational repair and acts after the formation of Holliday junctions. Molecular characterization of the locus revealed that there are three genes – ruvA, ruvB and ruvC; mutations in any one of the genes (...) confer the same phenotype. Recently, the RuvC protein was found to be a Holliday junction resolvase. At first glance, the resolving activity of RuvC alone would appear to be sufficient for the separation of recombining chromosomes. However, in vitro studies show that the filament of RecA protein is unable to dissociate from the products of the recombination reaction. Thus, in vivo, even if the Holliday junctions are resolved by RuvC, RecA filament must be holding two DNA duplexes together. New findings about enzymatic activities of RuvA and RuvB proteins foster the hope that the machinery for removing the RecA filament from DNA has been found. (shrink)

Inhibiting the progress of replication forks in E. coli makes them susceptible to breakage. Broken replication forks are evidently reassembled by the RecBCD recombinational repair pathway. These findings explain a particular pattern of DNA degradation during inhibition of chromosomal replication, the role of recombination in the viability of mutants with displaced replication origin, and hyper‐recombination observed in the Terminus of the E. coli chromosome in rnh mutants. Breakage and repair of inhibited replication forks could be the reason for the recombination‐dependence (...) of inducible stable DNA replication. A mechanism by which RecABCD‐dependent recombination between very short inverted repeats may help E. coli to invert an operon, transcribed in the direction opposite to that of DNA replication, is discussed. (shrink)

DNA polymerases which duplicate cellular chromosomes are multiprotein complexes. The individual functions of the many proteins required to duplicate a chromosome are not fully understood. The multiprotein complex which duplicates the Escherichia coli chromosome, DNA polymerase III holoenzyme (holoenzyme), contains a DNA polymerase subunit and nine accessory proteins. This report summarizes our current understanding of the individual functions of the accessory proteins within the holoenzyme, lending insight into why a chromosomal replicase needs such a complex structure.

Threonine is an essential amino acid for mammals and birds and an adequate supply is necessary for growth and maintenance. Its production has become the aim of metabolic bioengineering and genetic manipulations. We propose in this paper a rational approach for increasing threonine production in anE. coli strain based on metabolic control theory. We have derived a way to measure the control coefficients of threonine pathwayin vivo. The method consists in modelling the results of presteady-state experiments. Thein vivo concentrations and (...) activities of the enzymes can then be measured and introduced into the model, so that thein vivo steady-state of the pathway can be evaluated. With such a model it is possible to calculate the theoretical values of the control coefficients of the threonine synthesis fluxin vivo. (shrink)

The postulate that a stalled/collapsed replication fork will be generated when the replication complex encounters a UV‐induced lesion in the template for leading‐strand DNA synthesis is based on the model of semi‐discontinuous DNA replication. A review of existing data indicates that the semi‐discontinuous DNA replication model is supported by data from in vitro studies, while the discontinuous DNA replication model is supported by in vivo studies in Escherichia coli. Until the question of whether DNA replicates discontinuously in one or both (...) strands is clearly resolved, any model building based on either one of the two DNA replication models should be treated with caution. BioEssays 27:633–636, 2005. © 2005 Wiley Periodicals, Inc. (shrink)

Research in infection biology aims to understand the complex nature of host–pathogen interactions. While this knowledge facilitates strategies for preventing and treating diseases, it can also be intentionally misused to cause harm. Such dual-use risk is potentially high for highly pathogenic microbes such as Risk Group-3 (RG3) bacteria and RG4 viruses, which could be used in bioterrorism attacks. However, other pathogens such as influenza virus (IV) and enterohemorrhagic Escherichia coli (EHEC), usually classified as RG2 pathogens, also demonstrate high dual-use risk. (...) As the currently approved therapeutics against these pathogens are not satisfactorily effective, previous outbreaks of these pathogens caused enormous public fear, media attention and economic burden. In this interdisciplinary review, we summarize the current perspectives of dual-use research on IV and EHEC, and further highlight the dual-use risk associated with evolutionary experiments with these infectious pathogens. We support the need to carry out experiments pertaining to pathogen evolution, including to gain predictive insights on their evolutionary trajectories, which cannot be otherwise achieved with stand-alone theoretical models and epidemiological data. However, we also advocate for increased awareness and assessment strategies to better quantify the risks-versus-benefits associated with such evolutionary experiments. In addition to building public trust in dual-use research, we propose that these approaches can be extended to other pathogens currently classified as low risk, but bearing high dual-use potential, given the particular pressing nature of their rapid evolutionary potential. (shrink)

Over 80% of the genes in the E. coli chromosome express fewer than a hundred copies each of their protein products per cell. It is argued here that transcription of these genes is neither constitutive nor regulated by protein factors, but rather, induced by the act of replication. The utility of such replication‐induced (RI) transcription to the temporal regulation of synthesis of determinate quantities of low copy number (LCN) proteins is described. It is suggested that RI transcription may be necessitated, (...) as well as facilitated, by the folding of the bacterial chromosome into a compact nucleoid. Mechanistic aspects of the induction of transcription by replication are discussed with respect to the modulation of transcriptional initiation by negative supercoiling effects, promoter methylation status and derepression. It is shown that RI transcription offers plausible explanations for the constancy of the C period of the E. coli cell cycle and the remarkable conservation of gene order in the chromosomes of enteric bacteria. Some experimental tests of the hypothesis are proposed. (shrink)

DNA transfer directly from cell to cell (conjugation) is common among prokaryotes, particularly Gram‐negative bacteria like Escherichia coli. The phenomenon invariably requires a set of plasmid genes in the DNA donor cell. In addition, E. coli itself makes limited and specific contributions to the donor activity of strains carrying the conjugative plasmid F. These contributions have yet to be defined biochemically, but it is already clear that the cell envelope is an importan nexus between plasmid‐ and chromosome‐encoded proteins required for (...) the establishment and maintenance of DNA donor activity. (shrink)

This article outlines aconceptual framework for examining recentoutbreaks of E. coli O157:H7 infectionassociated with the consumption of beef in theUnited States. We argue that beef produced inthis country is generally safer frombacteriological contamination than in the past.Paradoxically, increasing intensification andconcentration in the meat subsector since theearly 1980s has (a) altered agro-food ecology,including characteristics of foodborne bacteriaand human physiology; (b) created conditionsfavorable for the rapid amplification of lowconcentrations of pathogens; and (c) reducedthe beef industry's flexibility to introducechanges necessary to preclude and/or (...) controlthe rapid spread of pathogens in meat and meatproducts. As a result, beef industry currentlyis capable of producing large quantities ofbacteriologically safe meat whilesimultaneously becoming more vulnerable to foodcontaminations that can be fatal in some cases.The limitations and effectiveness of a newregulatory regime, the HACCP (Hazard Analysisand Critical Control Points) system as well asother efforts to decontaminate the beef supplyare discussed. (shrink)

This paper deals with the application of the metabolic control theory, especially the measurement of control coefficients, to the threonine pathway inE. coli. The control coefficient of a step on a metabolic flux quantitatively assesses the flux response to the step variations. This concept is particularly relevant both in pathological situations (decrease in the activity of an enzymatic step in the metabolism) and in biotechnologies, where, on the contrary steps are amplified.Measurement of the control coefficients of the steps of a (...) metabolic network makes it possible to know those whose amplification should lead to a simultaneous increase in the fluxes. (shrink)