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Search Results: 1 - 10 of 10892 matches for " Pierre Jouannet "
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Zona pellucida from fertilised human oocytes induces a voltage-dependent calcium influx and the acrosome reaction in spermatozoa, but cannot be penetrated by sperm
Catherine Patrat, Jana Auer, Patricia Fauque, Roger L Leandri, Pierre Jouannet, Catherine Serres
BMC Developmental Biology , 2006, DOI: 10.1186/1471-213x-6-59
Abstract: The hZP of fertilised oocytes retained their ability to bind sperm (albeit less strongly than that from unfertilised oocytes), to induce an intraspermatic calcium influx through voltage-dependent channels similar to that observed with hZP from unfertilised oocytes and to promote the acrosome reaction at a rate similar to that induced by the ZP of unfertilised oocytes (61.6 ± 6.2% vs60.7 ± 9.1% respectively). Conversely, the rate of hZP penetrated by sperm was much lower for fertilised than for unfertilised oocytes (19% vs 57% respectively, p < 0.01). We investigated the status of ZP2 in the oocytes used in the functional tests, and demonstrated that sperm binding and acrosome reaction induction, but not ZP penetration, occurred whether or not ZP2 was cleaved.The change in ZP function induced by fertilisation could be different in human and mouse species. Our results suggest a zona blocking to polyspermy based at the sperm penetration level in humans.Sperm interaction with the extracellular matrix surrounding the oocyte, the zona pellucida (ZP), is a key step in mammalian fertilisation. The structure and function of the ZP were first studied in mice in the 1980s [1-3]. Mouse ZP contains three glycoproteins: ZP1, ZP2 and ZP3. ZP3 binds to primary receptors on capacitated spermatozoa, inducing a cascade of intraspermatic events including the biphasic calcium influx leading to the acrosome reaction (AR). Following the AR, spermatozoa remain bound to the ZP via ZP2; they then penetrate the ZP and fuse with the egg plasma membrane [4]. The fertilisation is followed by the fusion of peripheral cortical granules with the vitelline membrane, resulting in the discharge of the contents of these granules into the perivitelline space. This exocytosis modifies the ZP matrix such that sperm no longer bind to or penetrate ZP, preventing polyspermy.Our understanding at a molecular level of gamete interaction in humans is much more restricted than for mice and other mammalian species
Assisted Reproductive Technology affects developmental kinetics, H19 Imprinting Control Region methylation and H19 gene expression in individual mouse embryos
Patricia Fauque, Pierre Jouannet, Corinne Lesaffre, Marie-Anne Ripoche, Luisa Dandolo, Daniel Vaiman, Hélène Jammes
BMC Developmental Biology , 2007, DOI: 10.1186/1471-213x-7-116
Abstract: In this study, different experimental groups were established to obtain embryos from superovulated and non-superovulated females, either from in vivo or in vitro fertilized oocytes, themselves grown in vitro or not. The embryos were cultured either in M16 medium or in G1.2/G2.2 sequential medium. The methylation status of H19 Imprinting Control Region (ICR) and H19 promoter was assessed, as well as the gene expression level of H19, in individual blastocysts. In parallel, we have evaluated embryo cleavage kinetics and recorded morphological data.We show that:1. The culture medium influences early embryo development with faster cleavage kinetics for culture in G1.2/G2.2 medium compared to M16 medium.2. Epigenetic alterations of the H19 ICR and H19 PP are influenced by the fertilization method since methylation anomalies were observed only in the in vitro fertilized subgroup, however to different degrees according to the culture medium.3. Superovulation clearly disrupted H19 gene expression in individual blastocysts. Moreover, when embryos were cultured in vitro after either in vivo or in vitro fertilization, the percentage of blastocysts which expressed H19 was higher in G1.2/G2.2 medium compared to M16.Compared to previous reports utilizing pools of embryos, our study enables us to emphasize a high individual variability of blastocysts in the H19 ICR and H19 promoter methylation and H19 gene expression, with a striking effect of each manipulation associated to ART practices. Our results suggest that H19 could be used as a sensor of the epigenetic disturbance of the utilized techniques.Many studies have focused on the effects of Assisted Reproductive Technology (ART) on children's health. ART babies now account for approximately 2.2% and 0.6% of all births in France and in the United States, respectively [1]. Singleton pregnancies obtained after ART are at a higher risk for adverse perinatal outcomes than natural pregnancies. These risks include perinatal mortality, p
Optimal Timing for Oocyte Denudation and Intracytoplasmic Sperm Injection
Catherine Patrat,Aida Kaffel,Lucie Delaroche,Juliette Guibert,Pierre Jouannet,Sylvie Epelboin,Dominique De Ziegler,Jean-Philippe Wolf,Patricia Fauque
Obstetrics and Gynecology International , 2012, DOI: 10.1155/2012/403531
Abstract: Objectives. To analyze the impact of oocyte denudation and microinjection timings on intracytoplasmic sperm injection (ICSI) outcomes. Study Design. We included ICSI cycles with the following parameters: rank 1 or 2, female age years, male factor infertility, long protocol using GnRH agonist and rFSH for ovarian stimulation, and use of freshly ejaculated sperm ( ). Several ICSI parameters were analyzed according to the time between oocyte retrieval and denudation ( ) and the time between denudation and ICSI ( ) using a statistical logistic regression analysis. Results. Neither nor had a significant influence on the Metaphase II (MII) rate but the fertilisation rate (FR) showed a significant improvement when was longer (optimal results at hours) while FR significantly decreased with the increase of . Optimal implantation (IR) and pregnancy (PR) rates were obtained when was around 2 hours. Conclusion. Incubation of oocytes around 2 hours between retrieval and denudation may not increase MII rate but appears to lead to the optimal combination of FR and IR. 1. Introduction Intracytoplasmic sperm injection (ICSI) is the treatment of choice for couples with severe male infertility. The microinjection technique has been completely standardized but there is no common standard for the precise timings of all the procedures. No more than 7 studies focusing on the influence of ICSI procedure timings on the outcoming results were published [1–8], with discrepancies in the conclusions. Although it has been shown that incubation of oocytes for 2–6?h prior to IVF (In Vitro Fertilization) improves fertilization and pregnancy rates [9–12], there are some conflicting results regarding the timing of ICSI. It has been reported that a preincubation period between oocyte retrieval and injection in ICSI cycles improved the percentage of mature oocytes [5, 6], the fertilization rate [1, 6, 7], and the embryo quality [1, 2]. A long oocyte preincubation (9–11 hours) prior to ICSI is thought to have bad effects on embryo quality [2], probably due to oocyte ageing. However, other studies supported different results as no statistically significant differences in the fertilization [3, 4] or the pregnancy rates [2, 6] were found in preincubated oocytes during ICSI cycles. In theory, some problems may be associated with the injection time. Oocytes are retrieved prior to ovulation in the procedure of IVF or ICSI. According to some reports [13, 14], preovulatory oocytes are not fully mature, even though a first polar body is present. It is so called the cytoplasmic immaturity.
DEMOCRACIA CRISTIANA Y CONCERTACIóN: LOS CASOS DE CHILE, ITALIA Y ALEMANIA
WALKER,IGNACIO; JOUANNET,ANDRéS;
Revista de ciencia política (Santiago) , 2006, DOI: 10.4067/S0718-090X2006000200004
Abstract: is it only a coincidence that presently christian democracy -or sectors that belonged to it- form part of political coalitions with the social democrats or socialists in chile, italy and germany? without dismissing such a possibility due to the volatility of italian politics and the special circumstances that led to the formation of the coalition between merkel and spd in germany, the authors argue that perhaps there are more profound reasons that explain these political alliances. this is especially clear in the experience of the "concertación" in chile (1990-2010). based on a historic-descriptive approach, the authors argue that the crisis of the welfare state and the need for a new impulse in terms of economic growth, competitiveness and innovation, in europe, and the pervasive reality of poverty, inequality and exclusion, in latin america, call for a different kind of alliances to give political expression to the social majority. both processes should be understood within the broader context of the post cold war period, post-authoritarianism and globalization. to transform the social majority into a political majority, which is the true meaning of the experience of the "concertación", in chile, could well be what explains the current political alliances of christian democracy in these three countries. in addition, the rather secular character of christian democracy, in europe and latin america -contrary to what is usually thought- has facilitated this coming together of christian democracy and social democracy. finally, the diminishing ideological intensity, the dynamics of electoral competition and the existence of certain favourable and special circumstances, would help to explain the emergence of these political coalitions
DEMOCRACIA CRISTIANA Y CONCERTACIóN: LOS CASOS DE CHILE, ITALIA Y ALEMANIA
IGNACIO WALKER,ANDRéS JOUANNET
Revista de Ciencia Política , 2006,
Abstract: Será tan sólo una coincidencia que la Democracia Cristiana -o sectores de la misma- gobierne actualmente con la izquierda socialista o socialdemócrata, en Chile, Italia y Alemania? Sin descartar tal posibilidad, especialmente en consideración a la volatilidad político-electoral de Italia, y el carácter aparentemente coyuntural de la alianza entre la Merkel y la Social Democracia en Alemania, los autores sostienen que tal vez existan razones más profundas para explicar este tipo de coaliciones, teniendo particularmente en cuenta la experiencia de la "Concertación" en Chile (1990-2010). Basados en un enfoque histórico-descriptivo, se alan que la crisis del Estado de Bienestar, en Europa, y la necesidad de un nuevo impulso en términos de crecimiento económico, competitividad e innovación, y la realidad extendida de la pobreza, la desigualdad y la exclusión, en América Latina, en el contexto más global de la post-Guerra Fría y la globalización, hacen necesario algún tipo de alianza capaz de darle un cauce de expresión política a la nueva mayoría social. Transformar la mayoría social en una mayoría política, que es lo central de la experiencia de la Concertación en Chile, bien pudiera ser la fórmula que explica la actual política de alianzas de la democracia cristiana en los tres países mencionados. El carácter más secular que religioso de la Democracia Cristiana, tanto en Europa como en América Latina, contrariamente a lo que se piensa, facilitaría este encuentro entre Democracia Cristiana y Social Democracia. Finalmente, la menor intensidad ideológica, la dinámica de la competencia electoral y la existencia de ciertas coyunturas favorables, ayudarían a explicar el surgimiento de este nuevo tipo de coaliciones políticas Is it only a coincidence that presently Christian Democracy -or sectors that belonged to it- form part of political coalitions with the social democrats or socialists in Chile, Italy and Germany? Without dismissing such a possibility due to the volatility of Italian politics and the special circumstances that led to the formation of the coalition between Merkel and SPD in Germany, the authors argue that perhaps there are more profound reasons that explain these political alliances. This is especially clear in the experience of the "Concertación" in Chile (1990-2010). Based on a historic-descriptive approach, the authors argue that the crisis of the Welfare State and the need for a new impulse in terms of economic growth, competitiveness and innovation, in Europe, and the pervasive reality of poverty, inequality and exclusion, in Latin Americ
In Vitro Fertilization and Embryo Culture Strongly Impact the Placental Transcriptome in the Mouse Model
Patricia Fauque,Fran?oise Mondon,Franck Letourneur,Marie-Anne Ripoche,Laurent Journot,Sandrine Barbaux,Luisa Dandolo,Catherine Patrat,Jean-Philippe Wolf,Pierre Jouannet,Hélène Jammes,Daniel Vaiman
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0009218
Abstract: Assisted Reproductive Technologies (ART) are increasingly used in humans; however, their impact is now questioned. At blastocyst stage, the trophectoderm is directly in contact with an artificial medium environment, which can impact placental development. This study was designed to carry out an in-depth analysis of the placental transcriptome after ART in mice.
Seeing Spots: Photo-identification as a Regional Tool for Whale Shark Identification
K Brooks, D Rowat, SJ Pierce, D Jouannet, M Vely
Western Indian Ocean Journal of Marine Science , 2010,
Abstract: The identification of individual animals over temporal and spatial scales can provide robust estimates of population size and distribution. While marker tagging can provide an option to achieve this, it can be problematic both in terms of tag loss and the associated difficulties and effects of attaching the tags. Photo-identification of distinctive characteristics which remain stable over time has replaced tagging in some species but usage at regional scales has been hampered by a lack of standardisation of matching methods. We describe the use of a semi-automated computer program (I3S) for matching the spot patterns of whale sharks, Rhincodon typus, in the Seychelles aggregation and compare this to images captured from other areas in the Western Indian Ocean. Sharks totalling 443 individuals were uniquely identified in the Seychelles from 2001 – 2009, 109 of which were seen in multiple years. Conventional open mark-recapture models for 2004 – 2009 gave an abundance estimate of 469 to 557 sharks (95% C.I.). I3S digital fingerprints were shared with researchers in Djibouti, Mozambique, and Tanzania and, while no matches were found between locations, the ease with which regional comparisons were made will help to define whether the shark populations in these areas are distinct, enabling long-term and broad-scale regional comparisons.
Breakpoint Features of Genomic Rearrangements in Neuroblastoma with Unbalanced Translocations and Chromothripsis
Valentina Boeva, Stéphanie Jouannet, Romain Daveau, Valérie Combaret, Cécile Pierre-Eugène, Alex Cazes, Caroline Louis-Brennetot, Gudrun Schleiermacher, Sandrine Ferrand, Ga?lle Pierron, Alban Lermine, Thomas Rio Frio, Virginie Raynal, Gilles Vassal, Emmanuel Barillot, Olivier Delattre, Isabelle Janoueix-Lerosey
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0072182
Abstract: Neuroblastoma is a pediatric cancer of the peripheral nervous system in which structural chromosome aberrations are emblematic of aggressive tumors. In this study, we performed an in-depth analysis of somatic rearrangements in two neuroblastoma cell lines and two primary tumors using paired-end sequencing of mate-pair libraries and RNA-seq. The cell lines presented with typical genetic alterations of neuroblastoma and the two tumors belong to the group of neuroblastoma exhibiting a profile of chromothripsis. Inter and intra-chromosomal rearrangements were identified in the four samples, allowing in particular characterization of unbalanced translocations at high resolution. Using complementary experiments, we further characterized 51 rearrangements at the base pair resolution that revealed 59 DNA junctions. In a subset of cases, complex rearrangements were observed with templated insertion of fragments of nearby sequences. Although we did not identify known particular motifs in the local environment of the breakpoints, we documented frequent microhomologies at the junctions in both chromothripsis and non-chromothripsis associated breakpoints. RNA-seq experiments confirmed expression of several predicted chimeric genes and genes with disrupted exon structure including ALK, NBAS, FHIT, PTPRD and ODZ4. Our study therefore indicates that both non-homologous end joining-mediated repair and replicative processes may account for genomic rearrangements in neuroblastoma. RNA-seq analysis allows the identification of the subset of abnormal transcripts expressed from genomic rearrangements that may be involved in neuroblastoma oncogenesis.
Bending Fuchsian representations of fundamental groups of cusped surfaces in PU(2,1)
Pierre Will
Mathematics , 2011,
Abstract: We describe a family of representations of $\pi_1(\Sigma)$ in PU(2,1), where $\Sigma$ is a hyperbolic Riemann surface with at least one deleted point. This family is obtained by a bending process associated to an ideal triangulation of $\Sigma$. We give an explicit description of this family by describing a coordinates system in the spirit of shear coordinates on the Teichm\"uller space. We identify within this family new examples of discrete, faithful and type-preserving representations of $\pi_1(\Sigma)$. In turn, we obtain a 1-parameter family of embeddings of the Teichm\"uller space of $\Sigma$ in the PU(2,1)-representation variety of $\pi_1(\Sigma)$. These results generalise to arbitrary $\Sigma$ the results obtained in a previous paper for the 1-punctured torus.
Two Generator groups acting on the complex hyperbolic plane
Pierre Will
Mathematics , 2015,
Abstract: This is an expository article about groups generated by two isometries of the complex hyperbolic plane.
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