209 research outputs found
Control of the cell cycle during meiotic maturation of mouse oocytes
The overall aim of the work presented in this thesis is to better understand the molecular
mechanisms underlying the progression of the meiotic division in mammalian oocytes.
The first goal of this project was to investigate the relative contribution of securin and
cyclin B1 to the control of the protease separase during the indeterminate period of
metaphase II arrest. I found here that although there are conditions in which either
securin or MPF can prevent chromosome disjunction, such as during meiosis I, securin is the predominant inhibitor of separase during metaphase II arrest. Thus, CDK1
pharmacological inhibition as well as antibody inhibition of CDK1/cyclin B1 binding to separase, both failed to induce sister chromatid disjunction. Instead, securin morpholino knockdown induced sister chromatid separation, which could be rescued by injection of securin cRNA.
I also examined the effect of CDK1 and MAPK activities on securin stability. Inhibition of both kinases, but not either one alone, using roscovitine and UO126, induced the
premature destruction of securin during prometaphase of meiosis I. However, this effect
is not dependent on securin phosphorylation, given that mutagenesis of CDK1 and
MAPK phosphorylation sites on securin did not affect its stability.
Finally, I found that CDK1 and MAPK inhibition also causes the premature degradation of other APC/C substrates, such as cyclin B1 and geminin. Interestingly, only the D-box containing substrates and not Ken-box substrates were subject to such effect. However, this prometaphase I instability of the D-box substrates was apparently not mediated by APC/CCdc20 or APC/CCdh1, given that Cdc20 was also targeted for destruction and morpholino-knockdown of both Cdc20 and Cdh1 failed to rescue securin stability. Also, the inhibition of SCFÎČ-TrCP using the dominant negative mutant of its F-box protein (ÎČ-TrCPÎ) could not restore securin levels, suggesting it is not SCFÎČ-TrCP-dependent. Future
work will explore whether this effect could be attributed to activation of some meiosis-specific
APC/C co-activators or the core APC/C, which was recently reported of being
able to directly interact with the D-box containing substrates independently of Cdc20 and
Cdh1 (Passmore et al., 2003; Yamano et al., 2004)
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Effect of some Pseudomonas strains and Agave americana L. on wheat germination under salt stress
Currently, several efforts focus remedying the problem of agricultural soil salinity using eco-friendly strategies. This study aimed particularly the study of Triticum durum (durum wheat) seeds germination in the presence of Pseudomonas strains and hydro-alcoholic extract of Agave americana L. under saline stress conditions. The preliminary phytochemical screening of A. americana, phylogenetic identification and production of indole-3-acetic acid (IAA) by Pseudomonas strains, in vitro impact of hydro-alcoholic extract and Pseudomonas strains combination on salt stress resistance, preliminary effects of A. americana on Triticum durum germination and phytopathogenic fungi inhibition under salt stress were carried out using corresponding protocols. In in vitro trials, phytochemical screening revealed the richness of A. americana in polyphenols (1014.062±161.017 mM GA equivalent/g FW) and flavonoids (51.065±27.391 mg quercetin equivalent/g FW). The ability of Pseudomonas strains to produce the phytohormone indole-3-acetic acid (IAA) varied from 116.67±8.25 ”g/ml to 857.14±80.50 ”g/ml. The leaf extract of A. americana is an effective osmoprotectant that improves the resistance of the strain P1 Pseudomonas plecoglissicida to saline stress. In in vivo experiments, the extract of A. americana did not show any effect on the germination of wheat seeds. However, it effectively inhibited the contamination of seeds by phytopathogenic fungi during germination and saline conditions. Findings of the study revealed that Pseudomonas plecoglissicida and A. americana extract are very promising for the inhibition of phytopathogenic fungi and the alleviation of salt stress
Direct Power Control for AC/DC/ACConverters in Doubly Fed Induction Generators Based Wind Turbine
In this paper direct power control (DPC) strategy is applied to control a doubly fed induction generator (DFIG) based wind energy generation system. A three level NPC ac/dc/ac converter is controlled by direct power control method. The rotor side converter is controlled by a novelle switching table based a double active power hysteresis band method. The selects appropriates voltage vector based on the instantaneous errors between the reference and estimated values of active and reactive powers and rotor flux position. Also the grid side is controlled by direct power control based a grid voltage position to ensures a constant DC voltage, Simulation results on a demonstrate robust, precise, and fast dynamic behavior of system.DOI:http://dx.doi.org/10.11591/ijece.v2i3.284
Le mussem de MeknĂšs. Le dĂ©clin dâune tradition spirituelle
RĂ©sumĂ©Les mussem-s sont des fĂȘtes saisonniĂšres, Ă la fois foires et pĂšlerinages cĂ©lĂ©brĂ©s aux environs du sanctuaire dâun saint personnage. Au Maroc, lors des festivitĂ©s annuelles cĂ©lĂ©brant le jour de la naissance du prophĂšte Muhammad, le Palais royal organise Ă MeknĂšs le mussem du Chaykh al-KĂąmil, censĂ© reprĂ©senter le pĂšlerinage des disciples de la confrĂ©rie soufie des AĂŻssĂąwa. Cet article dĂ©crit et analyse lâorganisation et le fonctionnement de ce mussem dans le champ culturel et religieux du Maroc. Les donnĂ©es de lâauteur proviennent dâune enquĂȘte de terrain menĂ©e auprĂšs du public pĂšlerin, des membres de la confrĂ©rie des AĂŻssĂąwa, des hauts responsables de lâordre religieux et des autoritĂ©s publiques. Par une approche socio-anthropologique et historique, le but est de saisir la signification et les enjeux de ce mussem dans la sociĂ©tĂ© marocaine contemporaine pour conclure sur son dĂ©clin depuis les annĂ©es 1980.The mussem of MeknĂšs : The Decline of a Spiritual TraditionAbstractThe mussem-s are seasonal festivals, both celebrated pilgrimages and fairs around the shrine of a holy man. In Morocco, during the annual festivities celebrating the day of birth of the prophet Muhammad, the government organizes in MeknĂšs the mussem of the Shaykh al-Kamil, the pilgrimage for the members of the sufi brotherhood of AĂŻssĂąwa. This article describes and analyzes the organization and the functioning of this mussem in the field of culture and religion of Morocco. The Data of the author comes from an investigation conducted among the pilgrim audience, members of the brotherhood of AĂŻssĂąwa, senior officials of the religious order and public authorities. With a socio-anthropological and historical approach, the goal is to capture the meaning and the implications of this mussem in contemporary Moroccan society to conclude on the wane since the 80âs
Quelle didactique pour lâenseignement / apprentissage de la langue amazighe?
Mon propos porte sur les aspects didactiques de lâenseignement /apprentissage de la langue amazighe. Plus prĂ©cisĂ©ment, il est question des mĂ©thodes utilisĂ©es depuis lâintroduction de cette langue dans le systĂšme Ă©ducatif. Il nâest pas nĂ©cessaire de sâappesantir sur les aspects sociolinguistiques qui caractĂ©risent cette langue et qui constituent des « travers1 » pour les praticiens en charge de cet enseignement car « cette langue est non amĂ©nagĂ©e et Ă©clatĂ©e en dialectes2 » dont chacun dâeux a le statut de langue maternelle dans son aire gĂ©ographique qui lui est propre. Face Ă cette situation inĂ©dite dans lâinstitution scolaire, de nombreuses questions assez dĂ©licates ont alors surgi. Quelle variante enseignĂ©e et dans quelle rĂ©gion ? Avec quels outils didactiques ? Avec quels contenus ? Quelle mĂ©thode choisir ? Et quelle graphie utilisĂ©e
Analyse du manuel de langue amazighe de 7e A.F.
Je me propose dâanalyser le nouveau manuel de langueamazighe destinĂ© aux apprenants de 7 annĂ©e. Mon analyse seracentrĂ©e aussi bien sur les contenus linguistiques que sur lessoubassements des choix sociolinguistiques et didactiques. Pour ce faire, je commencerai par dresser un Ă©tat des lieux pour mieux situer le public visĂ© puis je procĂ©derai Ă un rapide descriptif avant de passer à lâanalyse proprement dite
Des soufis en banlieue parisienne
Cet article dĂ©crit et analyse lâorganisation et le fonctionnement dâune zÄwiya française de la confrĂ©rie soufie marocaine QĂądiriyya-BĂ»dchichiyya. Les donnĂ©es de lâauteur proviennent de lâobservation participante, dâentretiens libres et semi-directifs appliquĂ©s Ă une enquĂȘte de terrain Ă lâintĂ©rieur de lâune des zÄwiya-s de cette confrĂ©rie situĂ©e en banlieue parisienne. Par une approche microsociologique, le but est de saisir, dâune part, les modalitĂ©s selon lesquelles une confrĂ©rie maghrĂ©bine contemporaine sâimplante en France, et, dâautre part, ce que la doctrine mystique reprĂ©sente aux yeux dâadeptes vivant dans une sociĂ©tĂ© laĂŻque de tradition catholique.This article is a microsociological study of a French zÄwiya of the Moroccan soufi brotherhood QĂądiriyya-BĂ»dshishiyya. The data of the author come from the participating observation, of free and semi-directing interviews applied to an investigation inside one of the zÄwiya-s of the brotherhood located in Parisian suburbs. The aim is to discover how a contemporary North-African brotherhood takes root in France and what the mystical doctrine represents for the disciples who lives in a secular society of catholic tradition.Este artĂculo describe y analiza la organizaciĂłn y el funcionamiento de una zĂąwiya francesa de la cofradĂa sufi marroquĂ QĂądiriyya-BĂ»dshishiyya. Los datos del autor provienen de la observaciĂłn participante, de entrevistas abiertas y semi-dirigidas aplicadas a una investigaciĂłn de campo de tres semanas (febrero de 2004) dentro de una de las zĂąwiya-s de esta cofradĂa situada en la periferia de Paris. Desde un enfoque microsociolĂłgico, el objetivo es comprender, por un lado, las modalidades a travĂ©s de las cuales una cofradĂa magrebĂ contemporĂĄnea se implanta en Francia, y, por otro lado, lo que la doctrina mĂstica representa a los ojos de adeptos que viven en una sociedad laica de tradiciĂłn catĂłlica
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