Monique de Saint Martin

Characterization of two members of the cryptochrome/photolyase family from Ostreococcus tauri provides insights into the origin and evolution of cryptochromes.

Cryptochromes (Crys) are blue light receptors believed to have evolved from the DNA photolyase protein family, implying that light control and light protection share a common ancient origin. In this paper, we report the identification of five genes of the Cry/photolyase family (CPF) in two green algae of the Ostreococcus genus. Phylogenetic analyses were used to confidently assign three of these sequences to cyclobutane pyrimidine dimer (CPD) photolyases, one of them to a DASH-type Cry, and a third CPF gene has high homology with the recently described diatom CPF1 that displays a bifunctional activity. Both purified OtCPF1 and OtCPF2 proteins show non-covalent binding to flavin adenine dinucleotide (FAD), and additionally to 5,10-methenyl-tetrahydrofolate (MTHF) for OtCPF2. Expression analyses revealed that all five CPF members of Ostreococcus tauri are regulated by light. Furthermore, we show that OtCPF1 and OtCPF2 display photolyase activity and that OtCPF1 is able to interact with the CLOCK:BMAL heterodimer, transcription factors regulating circadian clock function in other organisms. Finally, we provide evidence for the involvement of OtCPF1 in the maintenance of the Ostreococcus circadian clock. This work improves our understanding of the evolutionary transition between photolyases and Crys.

Towards a dynamic approach to reconversions

Although they are often analysed as forms of reproduction, reconversions have been characterized as forms of mobility in a number of works. Both options are not strictly contradictory and can equally be justified. However, trying to better circumscribe this notion seems utterly necessary today. Although not pretending to offer a precise definition, the author mainly leans on research on the élite conducted in different geographical (France, Hungary, Russia) and historical contexts, and proposes a better-grounded and more heuristic approach to reconversions that would also permit them to be clearly distinguished from conversions.

La noblesse russe à l'épreuve de la révolution d'Octobre: représentations et reconversions

La quasi-totalite des anciens nobles, femmes et hommes, restes en URSS ou ayant emigre en France apres la revolution d’Octobre 1917, ont tente des reconversions, de fait sous la contrainte ; les recits recueillis par entretiens approfondis ou dans les archives privees font apparaitre des parcours chaotiques. Ainsi avons-nous tente en developpant une approche sociologique, de suivre la logique pratique qui guide les efforts et les investissements personnels de ces nobles, en prenant surtout en compte les representations du temps et les differentes ressources convertibles et en nous interessant aussi a la genese des transformations de la noblesse russe depuis les annees 1880. En URSS, les anciens nobles ne se sont pas seulement plus ou moins « adaptes » a la societe sovietique, mais ont aussi contribue a la formation de la structure sociale de l’URSS, notamment du milieu de l’« ancienne intelligentsia », compose des descendants des familles cultivees d’avant la revolution. En France, l’identite russe est pour beaucoup devenue plus importante que l’identite noble, mais les hierarchies de l’ancienne societe russe ne s’en sont pas moins souvent reproduites, avec toutefois quelques distorsions.

Fronteiras, trajetórias e experiências de rupturas

This paper analyzes different individual and family paths rather marked by social, professional, geographical and residential discontinuities. Members of the different groups that constitute French society were interviewed by a research team, between 2004 and 2007, to seize how families and individuals play with social and spatial borders, displace them, overstep them or construct them in their activities. Our results show that breaking given borders, as that of diploma, for instance, which is much valued by some actors, helps develop tendencies to overstep social borders or at least, not to naturalize them as much or even more than social or professional mobility itself. Spatial borders (most particularly country or district borders) are often mentioned in these interviews. The fact that they are perceived and played with is closely linked to such experiences of displacement and rupture.

Les reconversions culturelles : l'exemple de la noblesse

Les premiers resultats d’une recherche exploratoire realisee dans l’edition et dans les nouvelles entreprises culturelles constituees autour des châteaux (montage de spectacles, d’expositions) peuvent permettre de proposer des hypotheses sur les modalites et les facteurs explicatifs des reconversions des descendants de la noblesse. Ceux-ci tentent en effet de reconvertir leurs ressources symboliques (nom, titre, prestige) et leurs ressources sociales (large reseau de relations, appartenance a de grandes familles, manieres) en ressources economiques. Le developpement de l’edition et des professions culturelles, les reactions souvent favorables des autres groupes en concurrence, le volume et la structure des differentes ressources que les aristocrates detenaient, les caracteristiques et l’histoire de la famille et des acteurs constituent quelques-uns des facteurs qui ont pu inciter les aristocrates aux reconversions.

Les facteurs de l'élimination et de la sélection différentielles dans les études de sciences@@@Les facteurs de l'elimination et de la selection differentielles dans les etudes de sciences

Monique de Saint Martin : Differentialausscheidungs — und Auslesungsfaktoren im wissenschaftlichen Studium. Die Statistiken zeigen, dass die Arbeitersohne in den wissenschaftlichen Fakultaten zahlreicher vertreten sind als in den andern. Betrachtet man jedoch die Gesamtheit des wissenschaftlichen Hochschulwesens, d.h. inbegriffen die Vorbereitungsklassen und technischen Hochschulen, so sieht man, dass der Prozentsatz der Arbeitersohne unter den Studenten immer ungefahr der gleiche ist, ob es sich um rein wissenschaftliche oder andere Fakultaten handelt. Eine bei 6 000 Wissenschaftstudenten des ersten und zweiten « cycle » an 12 Universitaten und akademischen Hochschulen durchgefuhrte Untersuchung beweisst, dass die wissenschaftlichen, genau wie die Studenten der anderen Facher, dem Einfluss unzahliger Auslese- und Ausscheidungsfaktoren unterworfen sind, die nie ganz unabhangig voneinander wirken. Um die Unterschiede in Laufbahn und Erfolg der Studenten wirklich zu verstehen, muss man ebenso das durch die Familie vermittelte Kulturgut, als die eigentliche Wirkung der Schule in Betracht ziehen.

Applications of radioactivity to the study of chromatographic analysis

With the help of radioactive elements the fixation of the ions Cl-, Br-, and I- on Chromatographic columns has been studied. A study lias also been made of the Chromatographic equilibria of systems containing a mixture of two of the above-mentioned ions. The observed order of the intensities of Chromatographic adsorption is the same as that obtained in the case of the amberlites. It is not in accordance with the law concerning ionic radii but may be interpreted by means of tlie electronegativities of PAULING.

Sur l'application de la radioactivité a l'étude de l'analyse chromatographique : Quelques remarques sur la fixation des ions halogénhydriques

With the help of radioactive elements the fixation of the ions Cl-, Br-, and I- on Chromatographic columns has been studied. A study lias also been made of the Chromatographic equilibria of systems containing a mixture of two of the above-mentioned ions. The observed order of the intensities of Chromatographic adsorption is the same as that obtained in the case of the amberlites. It is not in accordance with the law concerning ionic radii but may be interpreted by means of tlie electronegativities of PAULING.