Zona pellucida from fertilised human oocytes induces a voltage-dependent calcium influx and the acrosome reaction in spermatozoa, but cannot be penetrated by sperm

BACKGROUND: The functions of three zona glycoproteins, ZP1, ZP2 and ZP3 during the sperm-zona pellucida (ZP) interaction are now well established in mice. The expression of an additional zona glycoprotein, ZPB/4, in humans, led us to reconsider the classical mouse model of gamete interaction. We investigated the various functions of human ZP (hZP) during the interaction of spermatozoa with fertilised and unfertilised oocytes. RESULTS: 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. CONCLUSION: 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

Gene expression regulation in the context of mouse interspecific mosaic genomes

The testis transcriptome of mouse strains containing homozygous segments of Mus spretus origin in a Mus musculus background was analyzed

Fidgetin-Like1 Is a Strong Candidate for a Dynamic Impairment of Male Meiosis Leading to Reduced Testis Weight in Mice

Chantier qualité GAInternational audienceBACKGROUND: In a previous work, using an interspecific recombinant congenic mouse model, we reported a genomic region of 23 Mb on mouse chromosome 11 implicated in testis weight decrease and moderate teratozoospermia (∼20-30%), a Quantitative Trait Locus (QTL) called Ltw1. The objective of the present study is to identify the gene underlying this phenotype. RESULTS: In the present study, we refined the QTL position to a 5 Mb fragment encompassing only 11 genes. We showed that the low testis weight phenotype was due to kinetic alterations occurring during the first wave of the spermatogenesis where we could point out to an abnormal lengthening of spermatocyte prophase. We identify Fidgetin-like 1 (Fignl1) as the gene underlying the phenotype, since if fulfilled both the physiological and molecular characteristics required. Indeed, amongst the 11 positional candidates it is the only gene that is expressed during meiosis at the spermatocyte stage, and that presents with non-synonymous coding variations differentiating the two mouse strains at the origin of the cross. CONCLUSIONS: This work prompted us to propose Fignl1 as a novel actor in mammal's male meiosis dynamics which has fundamental interest. Besides, this gene is a new potential candidate for human infertilities caused by teratozoospermia and blockades of spermatogenesis. In addition this study demonstrates that interspecific models may be useful for understanding complex quantitative traits

Expression, localization and functions in acrosome reaction and sperm motility of Ca(V)3.1 and Ca(V)3.2 channels in sperm cells: an evaluation from Ca(V)3.1 and Ca(V)3.2 deficient mice.: Cav3.1/3.2 channel functions in sperm physiology

International audienceIn spermatozoa, voltage-dependent calcium channels (VDCC) have been involved in different cellular functions like acrosome reaction (AR) and sperm motility. Multiple types of VDCC are present and their relative contribution is still a matter of debate. Based mostly on pharmacological studies, low-voltage-activated calcium channels (LVA-CC), responsible of the inward current in spermatocytes, were described as essential for AR in sperm. The development of Ca(V)3.1 or Ca(V)3.2 null mice provided the opportunity to evaluate the involvement of such LVA-CC in AR and sperm motility, independently of pharmacological tools. The inward current was fully abolished in spermatogenic cells from Ca(V)3.2 deficient mice. This current is thus only due to Ca(V)3.2 channels. We showed that Ca(V)3.2 channels were maintained in sperm by Western-blot and immunohistochemistry experiments. Calcium imaging experiments revealed that calcium influx in response to KCl was reduced in Ca(V)3.2 null sperm in comparison to control cells, demonstrating that Ca(V)3.2 channels were functional. On the other hand, no difference was noticed in calcium signaling induced by zona pellucida. Moreover, neither biochemical nor functional experiments, suggested the presence of Ca(V)3.1 channels in sperm. Despite the Ca(V)3.2 channels contribution in KCl-induced calcium influx, the reproduction parameters remained intact in Ca(V)3.2 deficient mice. These data demonstrate that in sperm, besides Ca(V)3.2 channels, other types of VDCC are activated during the voltage-dependent calcium influx of AR, these channels likely belonging to high-voltage activated Ca(2+) channels family. The conclusion is that voltage-dependent calcium influx during AR is due to the opening of redundant families of calcium channels

Identification of Quantitative Trait Loci responsible for embryonic lethality in mice assessed by ultrasonography

Chantier qualité GAInternational audienceRecurrent Spontaneous Abortion (RSA) is a frequent pathology affecting 1 to 5% of couples. In ~50 % of cases, the aetiology is unknown suggesting a subtle interaction between genetic and environmental factors. Previous attempts to describe genetic factors using the candidate gene approach have been relatively unsuccessful due to the physiological, cellular and genetic complexity of mammalian reproduction. Indeed, fertility can be considered as a quantitative feature resulting from the interaction of genetic, epigenetic and environmental factors. Herein, we identified Quantitative Trait Loci (QTL) associated with diverse embryonic lethality phenotypes and the subsequent embryonic resorption in 39 inter-specific recombinant congenic mice strains, using in vivo ultrasound bio-microscopy. The short chromosomal intervals related to the phenotypes will facilitate the study of a restricted number of candidate genes which are potentially dysregulated in patients affected by RSA

Rôle de l’expérience professionnelle dans le milieu des soins sur les performances et la motivation des étudiants en soins infirmiers dans un dispositif hybride

Les dispositifs d’enseignement hybride dans la formation en soins infirmiers sont peu représentés dans la littérature scientifique (Li et al., 2019). Pourtant le public de cette formation est particulier puisque nombre d’étudiants ont une expérience professionnelle dans le milieu des soins avant même de débuter leur cursus. Cette étude se propose d’identifier les variables qui prédisent les performances des étudiants, notamment en prenant en compte leur expérience professionnelle. Dans un dispositif hybride alternant un enseignement sous la forme de capsules vidéo, accompagnées d’évaluations formatives en ligne et des travaux dirigés en présentiel, des variables liées à la motivation et à la participation sont mesurées auprès de 143 étudiants. Les résultats montrent que les comportements observables et la motivation des étudiants influencent différemment leurs performances selon qu’ils ont ou non une expérience professionnelle préalable. Ces résultats sont décrits et discutés et pourraient constituer un point d’ancrage à une littérature scientifique combinant l’enseignement hybride et la formation en soins infirmiers.Blended learning in nursing education is currently hardly represented in the scientific literature (McCutcheon et al., 2015). However, the public of this education is unusual, especially since many of them already have a professional background in the healthcare environment. Using multiple regression models, this study aims to identify predictive variables of student performance according to their professional background. Variables related to motivation and participation were measured among 143 students in a blended course alternating videos, online formative assessments, and face-to-face supervised exercises. Results showed that participation and motivation influence their performance differently depending on whether they have prior professional experience. These results are described and discussed and could be an anchor for a scientific literature combining blended and nursing education

Motivation, participation et performances des étudiants dans deux dispositifs hybrides

peer reviewedCette recherche vise à mieux comprendre le comportement des étudiants bénéficiant de cours dispensés dans un format hybride. Plus particulièrement, nous étudions la motivation, la participation et les performances des étudiants (N=156) dans deux dispositifs hybrides en condition réelle. Après avoir formalisé les deux dispositifs d’enseignement mis en place en formation de soins infirmiers, un examen des liens entre les caractéristiques des dispositifs et les différentes variables relatives à la motivation, la participation et les performances a été réalisé. En parallèle, une comparaison entre les deux dispositifs est proposée. Les résultats montrent que les deux dispositifs, qui se différencient essentiellement au niveau des activités en présentiel, permettent une augmentation des performances. Néanmoins, les variables qui prédisent les performances diffèrent selon le dispositif : les connaissances préalables et les buts de maitrise-approche dans le dispositif « situations » ; les buts de performance-approche et la régulation externe dans le dispositif « synthèses ». La participation en ligne des étudiants est relativement faible et ne prédit pas les performances. Ces résultats viennent compléter la littérature sur les relations entre ces différentes variables dans les dispositifs hybrides, et particulièrement sur les activités proposées en présentiel.This study aims to better understand the behavior of students taking blended courses. Specifically, we study the motivation, participation, and performance of students (N=156) in two blended courses under ecological conditions. After the formalization of two courses implemented in nursing schools, an analysis of the relationships between the characteristics of the courses and different variables related to motivation, participation and performance was conducted. In parallel, a comparison between the two courses is proposed. The results show that the two courses, which differ essentially in the face-to-face activities, improve student performance. However, the variables that influence performance are different in each of them: prior knowledge and mastery-approach goals in the "situations" course; performance-approach goals and external regulation in the "syntheses" course. Online participation is relatively low in both courses and does not predict student performance. These results complete the literature on the relationships between these different variables in blended learning, and particularly on the face-to-face activities."Investissements d'Avenir'' (16-IDEX-0001 CAP 20-25 - programme LIA

Refined mapping of a quantitative trait locus on chromosome 1 responsible for mouse embryonic death

Recurrent spontaneous abortion (RSA) is defined as the loss of three or more consecutive pregnancies during the first trimester of embryonic intrauterine development. This kind of human infertility is frequent among the general population since it affects 1 to 5% of women. In half of the cases the etiology remains unelucidated. In the present study, we used interspecific recombinant congenic mouse strains (IRCS) in the aim to identify genes responsible for embryonic lethality. Applying a cartographic approach using a genotype/phenotype association, we identified a minimal QTL region, of about 6 Mb on chromosome 1, responsible for a high rate of embryonic death (similar to 30%). Genetic analysis suggests that the observed phenotype is linked to uterine dysfunction. Transcriptomic analysis of the uterine tissue revealed a preferential deregulation of genes of this region compared to the rest of the genome. Some genes from the QTL region are associated with VEGF signaling, mTOR signaling and ubiquitine/proteasome-protein degradation pathways. This work may contribute to elucidate the molecular basis of a multifactorial and complex human disorder as RSA

Bat Rabies in Massachusetts, USA, 1985–2009

To investigate rabies in Massachusetts, we analyzed bat rabies test results before and after introduction of raccoon variant rabies and after release of revised 1999 US Advisory Committee on Immunization Practices recommendations for rabies postexposure prophylaxis. Bat submissions were associated with level of rabies awareness and specific postexposure recommendations