Molecular biology, a widely used expression for a changeable meaning

The present article is the on-line equivalent of Preprint 310 of the Max-Planck-Institut für Wissenschaftsgeschichte (Berlin) and has been contributed as an oral communication in September 2005.On my side, I believe that I first encountered the expression “molecular biology” at the very beginning of my thesis work, in October 1964, when seeing an issue of the Journal of Molecular Biology, a journal then considered in the laboratory the smartest of the best journals in modern biology. However, even in Monod's and Jacob's laboratories, the words “molecular biology” were not in routine use among us, whereas bacterial genetics, gene expression, negative and positive regulation, models, biophysics, operon, replication and replicon, etc were much more frequently used to speak of what was going on. In my opinion, the stepwise generalization of the use of “molecular” and “molecular biology” reflects distinct periods of doing science through molecular approaches, but does not attribute a unified meaning to the expression “molecular biology”

Créationnisme contre théorie de l'évolution : Vraie controverse ou faux débat ?

Cet article est destiné à La Science au Présent, Editions de l'Encyclopaedia Universalis, Paris.Il est de la liberté de chacun de tenir le créationnisme pour la vérité. Le point important commun aux tentatives créationnistes est de tenter de donner à une explication religieuse, le même statut épistémologique qu'une théorie scientifique et par conséquent de tenter de l'imposer comme un enseignement scientifique. C'est cette entreprise que les scientifiques et les philosophes des sciences contestent. Le créationnisme a un statut métaphysique inhérent à la révélation ; le statut privilégié de l'évolution humaine suppose l'existence d'un projet divin, ce qui ne constitue pas une théorie scientifique. La théorie de l'évolution assemble les données acquises par les sciences du vivant en un ensemble ordonné et prédictif : elle a un statut de théorie scientifique. Dogme religieux et théorie scientifique n'ont pas le même statut épistéomologique et ceci devrait suffire à clarifier le problème. Il n'en reste pas moins que le bon accueil persistant fait aux différentes formes du créationnisme traduit le fait qu'une théorie scientifique a bien de la peine à être comprise lorsqu'elle ne va pas dans le sens de l'évidence sensible et surtout lorsqu'elle bouscule certaines notions fondatrices d'une des bases de la culture occidentale

De l'animal expérimental au modèle en recherche biomédicale.

Cet article est destiné à la Revue PhilosophiqueSince the beginning of experimentation in biology, animals have been used to study processes that cannot be approached on human beings. The developement since 1985, of techniques aimed at precisely inactivationg mouse genes suspected to be involved in human diseases, has produced mice « model of human diseases », under the implicit assumption of an identity of physio-pathological processes in man and mouse. The passage from model for... to model of... is discussed in the present paper, along with the compulsory come back of a kind of experimentation on man, so as to take into account human specificities.Depuis le début de l'expérimentation en biologie, les animaux sont utilisés pour étudier des phénomènes inabordables chez l'homme. Le développement depuis 1985, de procédures d'inactivation chez la souris de gènes suspects d'un rôle en pathologie humaine, a produit des souris dites « modèles de maladies humaines » avec l'implicite d'une identité des processus physiopathologiques entre homme et souris. Le passage du modèle pour. au modèle de.. est discuté dans cet article ainsi que le retour nécessaire à une forme d'expérimentation sur l'homme pour tenir compte des spécificités de ce dernier

The designing of anti-diphtheria serotherapy at the Institut Pasteur (1888-1900) : the role of a supranational network of microbiologists

The development of anti-diphtheria serotherapy at the Institut Pasteur immediately follows the crisis known as the Pasteur-Koch debate. Research on diphtheria in Paris is indicative of the importance granted by Pasteurian scientists to Koch's school criticisms. After 1887, relations between French and German bacteriologists become more relaxed. A scientific and social network develops between them. It later extends to other fields of research at the Institut Pasteur, particularly therapeutic chemistry. The evolution of Franco-German relations at the Institut Pasteur is placed in the general framework of the way French universities considered German science

Le retour de la normalisation hygiéniste ?

Cet article est destiné à La Science au Présent, Editions de l'Encyclopaedia universalis, Paris.Ce débat porte sur l'application au 1er janvier 2008 du décret d'interdiction de fumer dans les lieux publics. En France, elle n'a provoqué que peu de protestations, des propos désabusés des buralistes et la faillite de bars à chicha. Comment a-t-on réussi à faire accepter, du moins en apparence, l'interdiction d'une pratique sociale triomphante il y a encore 30 ans ? Il ne s'agit pas de contester la nocivité des substances de toutes espèces contenues dans le tabac et les papiers à cigarettes. Mais, le point qui nous intéresse ici est d'examiner comment on est passé de la valorisation sociale d'une pratique à une politique de prévention ciblée puis à un jeu de mesures qui paraissent relever du même objectif mais qui concernent finalement la construction d'une nouvelle norme sociale

Multi-stage Friend murine erythroleukemia: molecular insights into oncogenic cooperation

The Friend virus SFFV (Spleen Focus Forming Virus) provokes an acute erythroblastosis in susceptible strains of mice that progresses to overt erythroleukemia by a multi-step process. For virologists, the Friend virus-induced disease has provided deep insights into the host mechanisms influencing susceptibility to retroviral infection and viremia. These insights have contributed to the understanding of HIV and other human retroviral infections. For cell biologists and oncologists, this leukemia has been a powerful experimental model to identify critical oncogenes involved in a multi-stage process, to understand the contribution of host genes to cancer development, and to investigate the mechanisms leading to cell growth autonomy. This model also provided an example of oncogenic reversion since Friend tumor cells can reinitiate their erythroid differentiation program when exposed in vitro to some chemical inducers. This review highlights recent findings demonstrating that the leukemic progression depends on the cooperation of at least two oncogenic events, one interfering with differentiation and one conferring a proliferative advantage. The Friend model of leukemia progression recapitulates the two phases of human acute myeloid leukemia (AML). Coupling of insights from studies on the Friend erythroleukemia with knowledge on AML might allow a better understanding of the molecular mechanisms involved in the evolution of leukemia in mice and men

Turning bacteria suspensions into a "superfluid"

The rheological response under simple shear of an active suspension of Escherichia coli is determined in a large range of shear rates and concentrations. The effective viscosity and the time scales characterizing the bacterial organization under shear are obtained. In the dilute regime, we bring evidences for a low shear Newtonian plateau characterized by a shear viscosity decreasing with concentration. In the semi-dilute regime, for particularly active bacteria, the suspension display a "super-fluid" like transition where the viscous resistance to shear vanishes, thus showing that macroscopically, the activity of pusher swimmers organized by shear, is able to fully overcome the dissipative effects due to viscous loss

Delocalization of the multifunctional RNA splicing factor TLS/FUS in hippocampal neurones: exclusion from the nucleus and accumulation in dendritic granules and spine heads.

International audienceLong-term synaptic change in the cortex and the hippocampus is believed to require the highly localized delivery and translation of mRNAs in the dendritic shafts and spines. The molecular interactions that underlie local signalling between synapses and mRNAs are still largely undefined. After purification from total brain extracts, the NMDA receptor is known to be associated with numerous proteins, including the multifunctional RNA-binding factor TLS (also called FUS). In non-neural tissue, TLS is a vital nuclear protein with roles in DNA repair, homologous recombination, transcriptional regulation and pre-mRNA processing. We have examined the distribution of TLS in hippocampal neurones, both in the adult brain and in mature primary cultures, using subcellular fractionation and immunofluorescence techniques. TLS immunoreactivity is largely excluded from the neuronal nucleus and is found in the cytosol and in somatodendritic particles. In some of these particles, TLS colocalizes with Sam68, a nuclear RNA-binding protein that we previously showed is incorporated into dendritic RNA granules. Some of the TLS clusters also colocalize with NMDA receptor clusters. Finally, TLS clusters are occasionally seen within spine heads. The apparent removal of TLS from the nucleus might result in specific patterns of mRNA transcription or splicing in hippocampal neurones. TLS may also contribute to steering, anchoring or regulating mRNAs at synaptic sites

Un aperçu du lexique de l’anglais dialectal

Le lexique de l’anglais dialectal a fait l’objet de nombreuses descriptions et de nombreuses études dialectologiques. Cet article montre la place qu’occupent les dialectes par rapport à la langue standard et à la langue de la Bible. Il s’arrête également sur la façon dont le lexique de l’anglais dialectal s’est constitué, à savoir par dérivation, composition et emprunt aux différentes langues avec lesquelles les locuteurs étaient en contact. De nombreux exemples illustrent la démonstration.The lexicon of dialectal English has been the subject of many descriptions and dialectological studies. This article shows the place of dialects in relation to the standard language and the language of the Bible. He also dwells on how the lexicon of dialectal English was constituted, namely by derivation, composition and borrowing from the different languages with which the speakers were in contact. Many examples illustrate the demonstration