Dans cet article, nous présentons le corpus « Multicultural Paris French » (MPF), en en montrant les enjeux théoriques et méthodologiques, ainsi que quelques directions d’exploitation. En visant des données non-standard illustrant ce qu’il est de coutume d’appeler « parler jeune », MPF repose sur une réflexion quant à la façon d’appréhender les situations propices à leur émergence, au-delà d’informations généralement retenues, d’ordres sociodémographiques ou ethniques, ou du degré de formalisme de l’échange. Si ces considérations ne sont évidemment pas évacuées, (...) elles sont combinées à d’autres qui concernent les effets de la relation entre locuteurs au moment de l’enregistrement. De ce fait, MPF apparaît comme un corpus original dans le champ des corpus de français parlé contemporain, tant du point de vue de la nature des données recueillies que de celui du traitement rendu possible par cette spécificité. (shrink)

Mos, a protein kinase, is specifically expressed and functions during meiotic maturation (or G2/M progression) of vertebrate oocytes. When expressed ectopically, however, it can also readily induce oncogenic transformation (or uncontrolled G1/S transitions) in somatic cells. In both of these cell types, Mos activates mitogen‐activated protein kinase (MAPK), which seems largely to mediate its different functions in both oocyte maturation and cellular transformation. In oocyte maturation, the Mos‐MAPK pathway probably serves to activate and stabilize M‐phase promoting factor (MPF) (possibly by (...) inhibiting some negative regulator(s) of this factor), while in cellular transformation, it seems to stabilize and activate the nuclear oncoprotein c‐Fos as well as to induce transcription of its gene. Thus, the different functions of Mos in oocytes and somatic cells may arise chiefly from its different MAPK‐mediated targets in the respective cell types. This review discusses the cellular basis that may enable Mos to act differently in oocytes and somatic cells. (shrink)

Mammalian oocytes exhibit a series of cell cycle transitions that coordinate the penultimate events of meiosis with the onset of embryogenesis at fertilization. The execution of these cell cycle transitions, at G2/M of meiosis‐I and metaphase/anaphase of meiosis I and II, involve both biosynthetic and post‐translational modifications that directly modulate centrosome and microtubule behavior. Specifically, somatic cells alter the signal transduction pathways in the oocyte and influence the expression of maturation promoting factor (MPF) and cytostatic factor (CSF) activity through a (...) microtubule‐dependent mechanism. The regulation of the oocytes' cell cycle machinery by hormone‐mediated somatic cell signals, involving both positive and negative stimuli, ensures that meiotic cell cycle progression is synchronized with the earliest pivotal events of mammalian reproduction. (shrink)

L’Action catholique spécialisée a donné naissance pendant le deuxième tiers du XXe siècle au Mouvement populaire des familles (MPF) et à ses dérivés. Ces Mouvements se donnaient pour but la formation et la promotion du monde ouvrier par lui-même, notamment par le biais de la famille. Les mères de famille au foyer prenaient en charge les intérêts de leur quartier et de toutes les familles ouvrières, assumant ainsi une maternité sociale. Elles organisaient des délégations auprès des mairies, créaient et géraient (...) des services (Femmes de prisonniers pendant la Seconde Guerre mondiale, services de machines à laver, travailleuses familiales pendant les trente glorieuses…). Le modèle d’action du MPF entre en déclin avec la modernisation du pays puis, dans les années 1970 avec l’accès généralisé des femmes au travail. (shrink)

A hypothesis for the control of eukaryotic DNA replication at the chromosomal level is proposed. The specific regulatory problem arises from the subdivision of the genome into thousands of individually replicating units, each of which must be duplicated a single time during S‐phase. The hypothesis is based on the finding of direct repeats at replication origins. Such repeats can adopt, beyond the full‐length double helical structure, another configuration exposing two single‐stranded loops that provide suitable templates for the initiation of DNA (...) replication. Any further initiation at the same origin is excluded as the single strandedness is eliminated by the replication process. Restoration of the initiable loop structure is proposed to occur by DNA‐protein rearrangements involved in chromosome condensation and duplication of the chromosomal protein backbone during mitosis. A possible role of the maturation promoting factor (MPF) is suggested. (shrink)

One of the profound changes in cellular morphology during mitosis is a massive alteration in the organization of microfilament cytoskeleton. It has been recently discovered that nonmuscle caldesmon, an actin and calmodulin binding microfilament‐associated protein of relative molecular mass Mr = 83000, is dissociated from microfilaments during mitosis, apparently as a consequence of mitosis‐specific phosphorylation. cdc2 kinase, which is a catalytic subunit of MPF (maturation or mitosis promoting factor), is found to be responsible for the mitosis‐specific phosphorylation of caldesmon. Because (...) caldesmon is implicated in the regulation of actin myosin interactions and/or microfilament organization, these results suggest that cdc2 kinase directly affects microfilament re‐organization during mitosis. (shrink)

One distinguishing feature of vertebrate oocyte meiosis is its discontinuity; oocytes are released from their prophase I arrest, usually by hormonal stimulation, only to again halt at metaphase II, where they await fertilization. The product of the c‐mos proto‐oncogene, Mos, is a key regulator of this maturation process. Mos is a serine‐threonine kinase that activates and/or stabilizes maturation‐promoting factor (MPF), the master cell cycle switch, through a pathway that involves the mitogen‐activated protein kinase (MAPK) cascade. Oocytes arrested at prophase I (...) lack detectable levels of Mos, which must be synthesized from a pool of maternal mRNAs for proper maturation. While Mos is necessary throughout maturation in Xenopus, it seems to be required only for meiosis II in the mouse. The translational activation of c‐mos mRNA at specific times during meiosis requires cytoplasmic polyadenylation. Cis‐ and trans‐acting factors for polyadenylation are, therefore, essential elements of maturation. (shrink)

Whilst the role of Maturation or M‐phase Promoting Factor (MPF) as a universal M‐phase regulator is well documented, much less attention has been paid to its role in nuclear transplantation experiments and especially to its influence upon remodelling of transplanted nuclei. There is currently wide acceptance that successful nuclear transplantation using differentiated nuclei is possible only in a cytoplasmic environment that is capable of inducing rapid nuclear de‐differentiation to a pronuclear‐like form. In this review our purpose is firstly, to outline (...) the conditions under which such remodelling can be induced, and secondly, to extend the debate to include a consideration of whether complete nuclear remodelling is an absolute necessity for clonal development. (shrink)

Mitotic entry and exit are switch‐like transitions that are driven by the activation and inactivation of Cdk1 and mitotic cyclins. This simple on/off reaction turns out to be a complex interplay of various reversible reactions, feedback loops, and thresholds that involve both the direct regulators of Cdk1 and its counteracting phosphatases. In this review, we summarize the interplay of the major components of the system and discuss how they work together to generate robustness, bistability, and irreversibility. We propose that it (...) may be beneficial to regard the entry and exit reactions as two separate reversible switches that are distinguished by differences in the state of phosphatase activity, mitotic proteolysis, and a dramatic rearrangement of cellular components after nuclear envelope breakdown, and discuss how the major Cdk1 activity thresholds could be determined for these transitions. (shrink)