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Search Results: 1 - 10 of 9505 matches for " Patricia Fauque "
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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
Introduire la dimension historique au collège en France
Review of Science, Mathematics and ICT Education , 2007,
Abstract: The introduction of historical elements within the secondary education of France actually tends to be generalized nowadays. Several activities that draw upon the history of science are proposed for 11-15 year-old students within the official teacher’s guide. The invention of Volta's battery in 1800, which is detailed here, is one of these. This activity is replaced in the context of the contemporary education system of France, as well as during the last thirty years when the introduction of the history of science in our secondary education has been evolving.
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.
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.
Scalable T^2 resistivity in a small single-component Fermi surface
Xiao Lin,Benoit Fauque,Kamran Behnia
Physics , 2015, DOI: 10.1126/science.aaa8655
Abstract: Scattering among electrons generates a distinct contribution to electrical resistivity that follows a quadratic temperature dependence. In strongly-correlated electron systems, the prefactor A of this T$^2$ resistivity scales with the magnitude of the electronic specific heat. Here, we show that one can change the magnitude of A by four orders of magnitude in metallic SrTiO3 by tuning the concentration of the carriers and consequently, the Fermi energy. The T$^2$ behavior persists in the single-band dilute limit despite the absence of two known mechanisms for T$^2$ behavior, distinct electron reservoirs and Umklapp processes. The results highlight the absence of a microscopic theory for momentum decay through electron-electron scattering in different Fermi liquids.
Field-induced polarisation of Dirac valleys in bismuth
Zengwei Zhu,Aurelie Collaudin,Benoit Fauque,Woun Kang,Kamran Behnia
Physics , 2011, DOI: 10.1038/nphys2111
Abstract: Electrons are offered a valley degree of freedom in presence of particular lattice structures. Manipulating valley degeneracy is the subject matter of an emerging field of investigation, mostly focused on charge transport in graphene. In bulk bismuth, electrons are known to present a threefold valley degeneracy and a Dirac dispersion in each valley. Here we show that because of their huge in-plane mass anisotropy, a flow of Dirac electrons along the trigonal axis is extremely sensitive to the orientation of in-plane magnetic field. Thus, a rotatable magnetic field can be used as a valley valve to tune the contribution of each valley to the total conductivity. According to our measurements, charge conductivity by carriers of a single valley can exceed four-fifth of the total conductivity in a wide range of temperature and magnetic field. At high temperature and low magnetic field, the three valleys are interchangeable and the three-fold symmetry of the underlying lattice is respected. As the temperature lowers and/or the magnetic field increases, this symmetry is spontaneously lost. The latter may be an experimental manifestation of the recently proposed valley-nematic Fermi liquid state.
Angle-resolved Landau spectrum of electrons and holes in bismuth
Zengwei Zhu,Benoit Fauque,Yuki Fuseya,Kamran Behnia
Physics , 2011, DOI: 10.1103/PhysRevB.84.115137
Abstract: In elemental bismuth, emptying the low-index Landau levels is accompanied by giant Nernst quantum oscillations. The Nernst response sharply peaks each time a Landau level intersects the chemical potential. By studying the evolution of these peaks when the field rotates in three perpendicular planes defined by three high-symmetry axes, we have mapped the angle-resolved Landau spectrum of the system up to 12 T. A theoretical model treating electrons at L point with an extended Dirac Hamiltonian is confronted with the experimentally-resolved spectrum. We obtain a set of theoretical parameters yielding a good but imperfect agreement between theory and experiment for all orientations of the magnetic field in space. The results confirm the relevance of the Dirac spectrum to the electron pockets and settle the longstanding uncertainty about the magnitude of the g-factor for holes. According to our analysis, a magnetic field exceeding 2.5 T applied along the bisectrix axis puts all carriers of the three electron pockets in their lowest($j=0$) spin-polarized Landau level. On top of this complex angle-dependent spectrum, experiment detects additional and unexpected Nernst peaks of unidentified origin.
Angle dependence of the orbital magnetoresistance in bismuth
Aurelie Collaudin,Benoit Fauque,Yuki Fuseya,Woun Kang,Kamran Behnia
Physics , 2015, DOI: 10.1103/PhysRevX.5.021022
Abstract: We present an extensive study of angle-dependent transverse magnetoresistance in bismuth, with a magnetic field perpendicular to the applied electric current and rotating in three distinct crystallographic planes. The observed angular oscillations are confronted with the expectations of semi-classic transport theory for a multi-valley system with anisotropic mobility and the agreement allows us to quantify the components of the mobility tensor for both electrons and holes. A quadratic temperature dependence is resolved. As Hartman argued long ago, this indicates that inelastic resistivity in bismuth is dominated by carrier-carrier scattering. At low temperature and high magnetic field, the threefold symmetry of the lattice is suddenly lost. Specifically, a $2\pi/3$ rotation of magnetic field around the trigonal axis modifies the amplitude of the magneto-resistance below a field-dependent temperature. By following the evolution of this anomaly as a function of temperature and magnetic field, we mapped the boundary in the (field, temperature) plane separating two electronic states. In the less-symmetric state, confined to low temperature and high magnetic field, the three Dirac valleys cease to be rotationally invariant. We discuss the possible origins of this spontaneous valley polarization, including a valley-nematic scenario.
Nernst effect and dimensionality in the quantum limit
Zengwei Zhu,Huan Yang,Benoit Fauque,Yakov Kopelevich,Kamran Behnia
Physics , 2009, DOI: 10.1038/nphys1437
Abstract: Nernst effect, the transverse voltage generated by a longitudinal thermal gradient in presence of magnetic field has recently emerged as a very sensitive, yet poorly understood, probe of electron organization in solids. Here we report on an experiment on graphite, a macroscopic stack of graphene layers, which establishes a fundamental link between dimensionality of an electronic system and its Nernst response. In sharp contrast with single-layer graphene, the Nernst signal sharply peaks whenever a Landau level meets the Fermi level. This points to the degrees of freedom provided by finite interlayer coupling as a source of enhanced thermoelectric response in the vicinity of the quantum limit. Since Landau quantization slices a three-dimensional Fermi surface, each intersection of a Landau level with the Fermi level modifies the Fermi surface topology. According to our results, the most prominent signature of such a topological phase transition emerges in the transverse thermoelectric response.
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