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Marcandre Sirard - One of the best experts on this subject based on the ideXlab platform.
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fsh withdrawal improves developmental Competence of Oocytes in the bovine model
Reproduction, 2012Co-Authors: Annelaure Nivet, Audrey Bunel, Remi Labrecque, Josee Belanger, Christian Vigneault, Patrick Blondin, Marcandre SirardAbstract:Combinations of genetic, environmental, and management factors are suspected to explain the loss in fertility observed for over 20 years in dairy cows. In some cases, IVF is used. When compared with in vivo embryo production, IVF resulted in low success rates until the FSH coasting process (FSH starvation after superstimulation) was introduced in 2002. Increased Competence associated with FSH withdrawal of aspirated Oocyte for in vitro maturation and IVF has not been optimized nor explained yet. The goal here was to determine and characterize the optimal Oocyte Competence acquisition window during the coasting period by determining blastocyst rates and follicular cohort development. Commercial milking cycling cows (n=6) were stimulated with 3 days of FSH (6×40 mg NIH Folltropin-V given at 12 h intervals) followed by a coasting period of 20, 44, 68, or 92 h. Each animal was exposed to the four conditions and served as its own control. At the scheduled time, transvaginal aspirations of immature Oocytes were performed followed by IVF of half the Oocytes. The outcomes were as follows: i) FSH coasting was optimal at a defined period: between 44 and 68 h of coasting; ii) The best estimated coasting duration was ∼54±7 h; iii) Under these conditions, the best statistical blastocyst rate estimation was ∼70%; iv) Between 44 and 68 h of coasting, follicle size group proportions were similar; v) Follicle diameter was not linearly associated with Competence. In conclusion, coasting duration is critical to harvest the Oocytes at the right moment of follicular differentiation.
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cumulus cell gene expression following the lh surge in bovine preovulatory follicles potential early markers of Oocyte Competence
Reproduction, 2010Co-Authors: Mourad Assidi, S J Dieleman, Marcandre SirardAbstract:Cumulus cells (CCs) are essential for Oocytes to reach full development competency and become fertilized. Many major functional properties of CCs are triggered by gonadotropins and governed by the Oocyte. Consequently, cumulus may reflect Oocyte quality and is often used for Oocyte selection. The most visible function of CCs is their ability for rapid extracellular matrix expansion after the LH surge. Although unexplained, LH induces the final maturation and improves Oocyte quality. To study the LH signaling and gene expression cascade patterns close to the germinal vesicle breakdown, bovine CCs collected at 2 h before and 6 h after the LH surge were hybridized to a custom-made microarray to better understand the LH genomic action and find differentially expressed genes associated with the LH-induced Oocyte final maturation. Functional genomic analysis of the 141 overexpressed and 161 underexpressed clones was performed according to their molecular functions, gene networks, and cell compartments. Following real-time PCR validation of our gene lists, some interesting pathways associated with the LH genomic action on CCs and their possible roles in Oocyte final maturation, ovulation, and fertilization are discussed. A list of early potential markers of Oocyte competency in vivo and in vitro is thereafter suggested. These early biomarkers are a preamble to understand the LH molecular pathways that trigger the final Oocyte Competence acquisition process in bovine.
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identification of potential markers of Oocyte Competence expressed in bovine cumulus cells matured with follicle stimulating hormone and or phorbol myristate acetate in vitro
Biology of Reproduction, 2008Co-Authors: Mourad Assidi, Isabelle Dufort, Atef Ali, Melanie Hamel, Omran Algriany, Steph Dielemann, Marcandre SirardAbstract:Oocyte Competence is the ability of the Oocyte to complete maturation, undergo successful fertilization, and reach the blastocyst stage. Cumulus cells are indispensable for this process. Their removal significantly affects the blastocyst rates. Moreover, the properties and functions of cumulus cells are regulated by the Oocyte. They also reflect the Oocyte’s degree of maturation. Our study was aimed at identifying markers of Oocyte Competence that are expressed in bovine cumulus cells. In a previous study in our laboratory, the blastocyst yield following FSH or phorbol myristate acetate (PMA) treatment was 45%. Therefore, we tested four sets of conditions during the first 6 h of in vitro maturation (IVM): FSH (0.1 lg/ml), PMA (0.1 lM), FSH + PMA, and negative control. Extracts from each IVM treatment were hybridized against the same negative control on a microarray containing a partial library of differentially expressed transcripts in the cumulus of competent Oocytes collected at 6 h after LH in vivo. Common positive clones between diffentially treated cells were selected, and 15 candidates were validated by real-time PCR. Based on this, the main candidates expressed in cumulus cells and that could be valuable and indirect markers of Oocyte Competence are hyaluronan synthase 2 (HAS2), inhibin b A( INHBA), epidermal growth factor receptor (EGFR), gremlin 1 (GREM1), betacellulin (BTC), CD44, tumor necrosis factor-induced protein 6 (TNFAIP6), and prostaglandin-endoperoxide synthase 2 (PTGS2). These biomarkers could be potential candidates to predict Oocyte Competence and to select higher-quality embryos for transfer. Additionally, these indirect predictors of Oocyte Competence and follicular health could improve our knowledge of gene expression patterns in the cumulus and yield insights into the molecular pathways controlling Oocyte Competence.
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contribution of the Oocyte to embryo quality
Theriogenology, 2006Co-Authors: Marcandre Sirard, Patrick Blondin, Francois Richard, Claude RobertAbstract:The ability of a bovine embryo to develop to the blastocyst stage, to implant and to generate a healthy offspring is not a simple process. To clarify the importance of the contribution of the Oocyte to the embryo quality, it is important to define more precisely the different types of Competence expressed by Oocytes. The ability to resume meiosis, to cleave upon fertilization to develop into a blastocyst, to induce pregnancy and to generate an healthy offspring are all separate events and succeeding in the first events does not ensure the success of subsequent ones. Furthermore, these events are associated with the three types of maturation processes observed in the Oocyte: meiotic, cytoplasmic and molecular. These abilities vary also upon the type of follicle the Oocytes is removed from. Larger or slow-growing follicles have been shown to foster better eggs than small or actively growing follicles. Hormonal stimulation can also affect Oocyte Competence with the nature of the effect (positive or negative) depending on timing and dose. This complex situation requires better definition of the contribution of each factor affecting the Oocyte Competence and the resulting embryo quality.
George W Smith - One of the best experts on this subject based on the ideXlab platform.
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evidence supporting a functional requirement of smad4 for bovine preimplantation embryonic development a potential link to embryotrophic actions of follistatin
Biology of Reproduction, 2014Co-Authors: Kyung Bon Lee, Kun Zhang, Joseph K Folger, Jason G Knott, George W SmithAbstract:Transforming growth factor beta (TGFbeta) superfamily signaling controls various aspects of female fertility. However, the functional roles of the TGFbeta-superfamily cognate signal transduction pathway components (e.g., SMAD2/3, SMAD4, SMAD1/5/8) in early embryonic development are not completely understood. We have previously demonstrated pronounced embryotrophic actions of the TGFbeta superfamily member-binding protein, follistatin, on Oocyte Competence in cattle. Given that SMAD4 is a common SMAD required for both SMAD2/3- and SMAD1/5/8-signaling pathways, the objectives of the present studies were to determine the temporal expression and functional role of SMAD4 in bovine early embryogenesis and whether embryotrophic actions of follistatin are SMAD4 dependent. SMAD4 mRNA is increased in bovine Oocytes during meiotic maturation, is maximal in 2-cell stage embryos, remains elevated through the 8-cell stage, and is decreased and remains low through the blastocyst stage. Ablation of SMAD4 via small interfering RNA microinjection of zygotes reduced proportions of embryos cleaving early and development to the 8- to 16-cell and blastocyst stages. Stimulatory effects of follistatin on early cleavage, but not on development to 8- to 16-cell and blastocyst stages, were observed in SMAD4-depleted embryos. Therefore, results suggest SMAD4 is obligatory for early embryonic development in cattle, and embryotrophic actions of follistatin on development to 8- to 16-cell and blastocyst stages are SMAD4 dependent.
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molecular determinants of Oocyte Competence potential functional role for maternal Oocyte derived follistatin in promoting bovine early embryogenesis
Endocrinology, 2009Co-Authors: Kyung Bon Lee, Anilkumar Bettegowda, J J Ireland, Gabbine Wee, George W SmithAbstract:Previous studies established a positive relationship between Oocyte Competence and follistatin mRNA abundance. Herein, we used the bovine model to test the hypothesis that follistatin plays a functional role in regulation of early embryogenesis. Treatment of early embryos with follistatin during in vitro culture (before embryonic genome activation) resulted in a dose-dependent decrease in time to first cleavage, increased numbers of blastocysts, and increased blastocyst total and trophectoderm cell numbers. To determine the requirement of endogenous follistatin for early embryogenesis, follistatin ablation/replacement studies were performed. Microinjection of follistatin small interfering RNA into zygotes reduced follistatin mRNA and protein and was accompanied by a reduction in number of embryos developing to eight- to 16-cell and blastocyst stages and reduced blastocyst total and trophectoderm cell numbers. Effects of follistatin ablation were rescued by culture of follistatin small interfering RNA-injected embryos in the presence of exogenous follistatin. To investigate whether follistatin regulation of early embryogenesis is potentially mediated via inhibition of endogenous activin activity, the effects of treatment of embryos with exogenous activin, SB-431542 (inhibitor of activin, TGF-beta, and nodal type I receptor signaling) and follistatin plus SB-431542 were investigated. Activin treatment mimicked positive effects of follistatin on time to first cleavage and blastocyst development, whereas negative effects of SB-431542 treatment were observed. Stimulatory effects of follistatin on embryogenesis were not blocked by SB-431542 treatment. Results support a functional role for Oocyte-derived follistatin in bovine early embryogenesis and suggest that observed effects of follistatin are likely not mediated by classical inhibition of activin activity.
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identification of novel bovine cumulus cell molecular markers predictive of Oocyte Competence functional and diagnostic implications
Biology of Reproduction, 2008Co-Authors: Anilkumar Bettegowda, Osman V Patel, Kyung Bon Lee, Kieun Park, Mohamed Salem, Jianbo Yao, J J Ireland, George W SmithAbstract:The present study was undertaken to discover molecular markers in bovine cumulus cells predictive of Oocyte Competence and to elucidate their functional significance. Differences in RNA transcript abundance in cumulus cells harvested from Oocytes of adult versus prepubertal animals (a model of poor Oocyte quality) were identified by microarray analysis. Four genes of interest encoding for the lysosomal cysteine proteinases cathepsins B, S, K, and Z and displaying greater transcript abundance in cumulus cells surrounding Oocytes harvested from prepubertal animals were chosen for further investigation. Greater mRNA abundance for such genes in cumulus cells of prepubertal Oocytes was confirmed by real-time RT-PCR. Elevated transcript abundance for cathepsins B, S, and Z also was observed in cumulus cells surrounding adult metaphase II Oocytes that developed to the blastocyst stage at a low percentage following parthenogenetic activation versus those that developed at a high percentage. Functional significance of cumulus cell cathepsin expression to Oocyte Competence was confirmed by treatment of cumulus-Oocyte complexes during in vitro Oocyte maturation with a cell-permeable cysteine proteinase (cathepsin) inhibitor. Inhibitor treatment decreased apoptotic nuclei in the cumulus layer and enhanced development of parthenogenetically activated and in vitro-fertilized adult Oocytes to the blastocyst stage. Stimulatory effects of inhibitor treatment during meiotic maturation on subsequent embryonic development were not observed when Oocytes were matured in the absence of cumulus cells. The present results support a functional role for cumulus cell cathepsins in compromised Oocyte Competence and suggest that cumulus cell cathepsin mRNA abundance may be predictive of Oocyte quality.
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functional genomics studies of Oocyte Competence evidence that reduced transcript abundance for follistatin is associated with poor developmental Competence of bovine Oocytes
Reproduction, 2007Co-Authors: Osman V Patel, Anilkumar Bettegowda, J J Ireland, Paul M Coussens, P Lonergan, George W SmithAbstract:Poor Oocyte Competence contributes to infertility in humans and livestock species. The molecular characteristics of such Oocytes are generally unknown. Objectives of the present studies were to identify differences in RNA transcript abundance in Oocytes and early embryos associated with reduced Oocyte Competence and development to the blastocyst stage. Microarray experiments were conducted using RNA isolated from germinal vesicle stage Oocytes collected from adult versus prepubertal animals (model of poor Oocyte Competence). A total of 193 genes displaying greater mRNA abundance in adult Oocytes and 223 genes displaying greater mRNA abundance in prepubertal Oocytes were detected. Subsequent gene ontology analysis of microarray data revealed significant overrepresentation of transcripts encoding for genes in hormone secretion classification within adult Oocytes and such genes were selected for further analysis. Real-time PCR experiments revealed greater abundance of mRNA for betaA and betaB subunits of inhibin/activin and follistatin, but not the alpha subunit in germinal vesicle stage Oocytes collected from adult versus prepubertal animals. Cumulus cell follistatin and betaB subunit mRNA abundance were similar in samples collected from prepubertal versus adult animals. A positive association between time of first cleavage (Oocyte Competence) and follistatin mRNA abundance was noted. Follistatin, betaB, and alpha subunit mRNAs were temporally regulated during early bovine embryogenesis and peaked at the 16-cell stage. Collectively, results demonstrate a positive association of follistatin mRNA abundance with Oocyte Competence in two distinct models and dynamic regulation of follistatin, betaB, and alpha subunit mRNAs in early embryos after initiation of transcription from the embryonic genome.
P J Hansen - One of the best experts on this subject based on the ideXlab platform.
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follicular fluid exosomes act on the bovine Oocyte to improve Oocyte Competence to support development and survival to heat shock
Reproduction Fertility and Development, 2019Co-Authors: T A Rodrigues, Jin Koh, P J Hansen, Kubra M Tuna, Abdel A Alli, Paula Tribulo, F F PaulalopesAbstract:Addition of follicular fluid to Oocyte maturation medium can affect cumulus cell function, increase Competence of the Oocytes to be fertilised and develop to the blastocyst stage and protect the Oocyte from heat shock. Here, it was tested whether exosomes in follicular fluid are responsible for the effects of follicular fluid on the function of the cumulus-Oocyte complex (COC). This was accomplished by culturing COCs during Oocyte maturation at 38.5°C (body temperature of the cow) or 41°C (heat shock) with follicular fluid or exosomes derived from follicular fluid and evaluating various aspects of function of the Oocyte and the embryo derived from it. Negative effects of heat shock on cleavage and blastocyst development, but not cumulus expansion, were reduced by follicular fluid and exosomes. The results support the idea that exosomes in follicular fluid play important roles during Oocyte maturation to enhance Oocyte function and protect it from stress.
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effect of season and exposure to heat stress on Oocyte Competence in holstein cows
Journal of Dairy Science, 2002Co-Authors: Y M Alkatanani, F F Paulalopes, P J HansenAbstract:Two experiments were conducted to evaluate seasonal variation in Oocyte Competence in Holstein cows and to test whether Oocyte quality in summer is affected by the magnitude of heat stress. In the first experiment, ovaries of Holstein cows were collected from a slaughterhouse and used to harvest Oocytes over 1 yr (n = 18 replicates). After in vitro maturation, fertilization, and culture, proportions of Oocytes and cleaved embryos that developed to blastocysts by d 8 were lower in the warm season compared with the cool season. In the second experiment, nonlactating Holstein cows were housed in one of the following three environments for 42 d before slaughter: heat stressed (housed with shade cloth in summer; n = 14); cooled (housed in a free-stall barn with foggers and fans in summer; n = 14); and winter (housed similar to the heat-stressed group; n = 12). Cows were slaughtered at d 18 to 19 of the estrous cycle. Oocytes from the two largest follicles per cow were aspirated and cultured individually. Ovaries were then dissected to collect additional Oocytes that were processed in a group for in vitro maturation, fertilization, and culture. Cleavage rates were similar among treatments, but none of the individually cultured Oocytes developed to blastocysts. For other Oocytes cultured in groups, proportions of Oocytes and cleaved embryos that developed to blastocysts by d 8 were lower in summer than winter with no difference between the heat-stressed and the cooled treatment groups. Summer depression in Oocyte quality in Holstein cows was evident, but cooling cows for 42 d did not alleviate that seasonal effect.
John De Vos - One of the best experts on this subject based on the ideXlab platform.
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human cumulus cells molecular signature in relation to Oocyte nuclear maturity stage
PLOS ONE, 2011Co-Authors: Z G Ouandaogo, D Haouzi, Said Assou, H Dechaud, Issac Jacques Kadoch, John De VosAbstract:The bi-directional communication between the Oocyte and the surrounding cumulus cells (CCs) is crucial for the acquisition of Oocyte Competence. We investigated the transcriptomic profile of human CCs isolated from mature and immature Oocytes under stimulated cycle. We used human Genome U133 Plus 2.0 microarrays to perform an extensive analysis of the genes expressed in human CCs obtained from patients undergoing intra-cytoplasmic sperm injection. CC samples were isolated from Oocyte at germinal vesicle, stage metaphase I and stage metaphase II. For microarray analysis, we used eight chips for each CC category. Significance analysis of microarray multiclass was used to analyze the microarray data. Validation was performed by RT-qPCR using an independent cohort of CC samples. We identified differentially over-expressed genes between the three CC categories. This study revealed a specific signature of gene expression in CCs issued from MII Oocyte compared with germinal vesicle and metaphase I. The CC gene expression profile, which is specific of MII mature Oocyte, can be useful as predictors of Oocyte quality.
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Involvement of BCL2 family members in the regulation of human Oocyte and early embryo survival and death: gene expression and beyond
Reproduction, 2011Co-Authors: Imène Boumela, D Haouzi, Said Assou, H Dechaud, John De Vos, Abdel Aouacheria, Alan H Handyside, Samir HamamahAbstract:In women, up to 99.9% of the Oocyte stockpile formed during fetal life is decimated by apoptosis. Apoptotic features are also detected in human preimplantation embryos both in vivo and in vitro. Despite the important consequences of cell death processes to Oocyte Competence and early embryonic development, little is known about its genetic and molecular control. B cell lymphoma-2 (BCL2) family proteins are major regulators of cell death and survival. Here, we present a literature review on BCL2 family expression and protein distribution in human and animal Oocytes and early embryos. Most of the studies focused on the expression of two antagonistic members: the founding and survival family member BCL2 and its proapoptotic homolog BAX. However, recent transcriptomic analyses have identified novel candidate genes related to Oocyte and/or early embryonic viability (such as BCL2L10) or commitment to apoptosis (e.g. BIK). Interestingly, some BCL2 proteins appear to be differentially distributed at the subcellular level during Oocyte maturation and early embryonic development, a process probably linked to the functional compartmentalization of the ooplasm and blastomere. Assessment of BCL2 family involvement in regulating the survival of human Oocytes and embryos may be of particular value for diagnosis and assisted reproductive technology. We suggest that implications of not only aberrant gene expression but also abnormal subcellular protein redistribution should be established in pathological conditions resulting in infertility.
F F Paulalopes - One of the best experts on this subject based on the ideXlab platform.
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follicular fluid exosomes act on the bovine Oocyte to improve Oocyte Competence to support development and survival to heat shock
Reproduction Fertility and Development, 2019Co-Authors: T A Rodrigues, Jin Koh, P J Hansen, Kubra M Tuna, Abdel A Alli, Paula Tribulo, F F PaulalopesAbstract:Addition of follicular fluid to Oocyte maturation medium can affect cumulus cell function, increase Competence of the Oocytes to be fertilised and develop to the blastocyst stage and protect the Oocyte from heat shock. Here, it was tested whether exosomes in follicular fluid are responsible for the effects of follicular fluid on the function of the cumulus-Oocyte complex (COC). This was accomplished by culturing COCs during Oocyte maturation at 38.5°C (body temperature of the cow) or 41°C (heat shock) with follicular fluid or exosomes derived from follicular fluid and evaluating various aspects of function of the Oocyte and the embryo derived from it. Negative effects of heat shock on cleavage and blastocyst development, but not cumulus expansion, were reduced by follicular fluid and exosomes. The results support the idea that exosomes in follicular fluid play important roles during Oocyte maturation to enhance Oocyte function and protect it from stress.
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effect of season and exposure to heat stress on Oocyte Competence in holstein cows
Journal of Dairy Science, 2002Co-Authors: Y M Alkatanani, F F Paulalopes, P J HansenAbstract:Two experiments were conducted to evaluate seasonal variation in Oocyte Competence in Holstein cows and to test whether Oocyte quality in summer is affected by the magnitude of heat stress. In the first experiment, ovaries of Holstein cows were collected from a slaughterhouse and used to harvest Oocytes over 1 yr (n = 18 replicates). After in vitro maturation, fertilization, and culture, proportions of Oocytes and cleaved embryos that developed to blastocysts by d 8 were lower in the warm season compared with the cool season. In the second experiment, nonlactating Holstein cows were housed in one of the following three environments for 42 d before slaughter: heat stressed (housed with shade cloth in summer; n = 14); cooled (housed in a free-stall barn with foggers and fans in summer; n = 14); and winter (housed similar to the heat-stressed group; n = 12). Cows were slaughtered at d 18 to 19 of the estrous cycle. Oocytes from the two largest follicles per cow were aspirated and cultured individually. Ovaries were then dissected to collect additional Oocytes that were processed in a group for in vitro maturation, fertilization, and culture. Cleavage rates were similar among treatments, but none of the individually cultured Oocytes developed to blastocysts. For other Oocytes cultured in groups, proportions of Oocytes and cleaved embryos that developed to blastocysts by d 8 were lower in summer than winter with no difference between the heat-stressed and the cooled treatment groups. Summer depression in Oocyte quality in Holstein cows was evident, but cooling cows for 42 d did not alleviate that seasonal effect.
