Project description:Cumulus cells provide an interesting biological material to perform analyses to understand the molecular clues determining oocyte competence. The objective of this study was to analyze the transcriptional differences between cumulus cells from oocytes exhibiting different developmental potentials following individual in vitro embryo production by RNA‐seq. Cumulus cells were allocated into three groups according to the developmental potential of the oocyte following fertilization: (1) oocytes developing to blastocysts (Bl+), (2) oocytes cleaving but arresting development before the blastocyst stage (Bl-), and (3) oocytes not cleaving (Cl-).
Project description:Cumulus cells surrounding the oocyte were sampled at the following stages: developmentally incompetent or poorly competent prophase I oocytes (NC1 oocytes), developmentally competent prophase I oocytes (C1 oocytes), and developmentally competent metaphase II oocytes (C2 oocytes). NC1 samples were collected from immature, unexpanded cumulus-oocytes complexes (COC) from prepubertal (3-week-old) mice, C1 samples from immature, unexpanded cumulus-oocytes complexes (COC) from adult (8-week-old) and C2 samples from mature, expanded COCs obtained from the oviduct from 8-week-old mice after standard superovulation protocol. Global transcriptional profiling was performed using cumulus cells collected from murine ovarian follicles during in vivo oocyte developmental competence acquisition. Cumulus cells were collected at 3 stages: early stage follicles (prophase I arrested oocytes, meiotically competent but developmentally incompetent, n=5), late stage follicles (prophase I arrested oocytes, meiotically competent and developmentally competent, n=5) and ovulatory follicles collected in vivo (metaphase II arrested oocytes, developmentally fully competent, n=5).
Project description:Somatic cells surrounding the oocyte were sampled at the following stages: developmentally incompetent or poorly competent prophase I oocytes (NC1 oocytes), developmentally competent prophase I oocytes (C1 oocytes), and developmentally competent metaphase II oocytes (C2 oocytes). NC1 cumulus cells (CC) were sampled from immature calf oocytes, C1 samples from immature cow oocytes, and C2 samples from in vivo matured cow oocytes. Global transcriptional profiling was performed using cumulus cells collected from bovine ovarian follicles during in vivo oocyte developmental competence acquisition. Cumulus cells were collected at 3 stages: early stage follicles (prophase I arrested oocytes, meiotically competent but developmentally incompetent, n=6), late stage follicles (prophase I arrested oocytes, meiotically competent and developmentally competent, n=6) and ovulatory follicles collected by ovum pick-up (OPU) in vivo (metaphase II arrested oocytes, developmentally fully competent, n=5).
Project description:Besides the established selection criteria based on embryo morphology and blastomere number, new parameters for embryo viability are needed to improve the clinical outcome of in vitro fertilization (IVF) and more particular of elective single embryo transfer (eSET). The aim of the study was to analyse genome-wide whether the embryo viability was reflected by the expression of genes in the oocyte surrounding cumulus cells. Early cleavage (EC) was chosen as a parameter for embryo viability. Experiment Overall Design: Consenting patients visiting the IVF clinic underwent an IVF or ICSI treatment. Immediately following ultrasound-guided cumulus-oocyte-complex (COC) retrieval, a proportion of the cumulus cells surrounding the oocyte were removed. Gene expression in cumulus cells from eight oocytes resulting in an early cleavage embryo (EC-CC; n=8) and from eight oocytes resulting in a non-EC embryo (NEC-CC; n=8) derived from six patients were analysed using microarrays (n=16). To exclude a differential gene expression due to differences in patient characteristics, samples were paired. From four patients both an EC-CC and a NEC-CC sample were used. From two additional patients two EC-CC as well as two NEC-CC samples were used.
Project description:Cumulus cells, surrounding the oocyte, play a key role in the acquisition of oocyte competence to be fertilized and to sustain early embryo development. Cumulus cells contribute to oocyte development by metabolizing energy substrates such as glutathione that may protect the oocyte from oxidative stress damages. The aim of our study was to compare transcriptomics profiles of cumulus enclosed (CEO) and cumulus denuded (CDO) oocytes after in vitro maturation. Global transcriptional profiling was performed using cumulus enclosed and cumulus denuded oocytes after in vitro maturation. Matured oocytes were obtained after 22h of maturation with (CEO) or without (CDO) cumulus cells and four replicates of 25 oocytes were collected for RNA extraction. Gene expression analysis was performed by comparing CDO versus CEO oocytes that represents a total of 8 slides using a dye swap hybridisation protocol.
Project description:Germ cells of most animals critically depend on piRNAs and Piwi proteins. Surprisingly, piRNAs in mouse oocytes are relatively rare and dispensable. We present compelling evidence for strong Piwi-piRNA expression in oocytes of other mammals. Human fetal oocytes express PIWIL2 and transposon-enriched piRNAs. Oocytes in adult human ovary express PIWIL1 and PIWIL2, while those in bovine ovary just express PIWIL1. In human, macaque and bovine ovaries we find piRNAs that resemble testis-borne pachytene piRNAs. Isolated bovine follicular oocytes were shown to contain abundant, relatively short piRNAs that preferentially target transposable elements. Using label-free quantitative proteome analysis we show that these maturing oocytes strongly and specifically express the thus-far uncharacterized PIWIL3 protein, alongside other known piRNA-pathway components. In bovine early embryos these piRNAs are still abundant, revealing a potential impact of piRNAs on mammalian embryogenesis. Our results reveal unexpected, highly dynamic piRNA pathways in mammalian oocytes and early embryos. Analyses of multiple small RNA libraries obtained from fetal/adult oocytes, cumulus cells, ovary, testis and 2-4 cell stage ivf embryos of multiple mammalian species.
Project description:Maturation of oocytes under in-vitro conditions (IVM) results in impaired developmental competence compared to oocytes matured in-vivo. Oocytes are closely coupled to their cumulus complex (COC) with a bidirectional exchange of metabolites. Therefore, elucidation of aberrations in cumulus metabolism in-vitro is crucial for a better mimicking of physiological maturation conditions. The aim of this study was the analysis of the equine cumulus cells proteome of single cumulus complexes of metaphase II oocytes matured either under in-vivo (n=8) or in-vitro (n=7) conditions. For in-vivo COC collection mares were slaughtered 30 hours after injection and cumulus complexes from the dominant follicle were harvested for analysis. For in-vitro maturation COCs were recovered from mares out of oestrous and matured for 30 hours in-vitro. COCs were separated in cumulus complexes and oocytes, and only cumulus of successfully matured oocytes was analyzed for this study. All cumulus samples were washed, snap frozen and stored in liquid nitrogen until preparation for analysis.
Project description:The oocyte forms a complex with their somatic cumulus cells within the follicle throughout the preovulatory maturation steps. Cumulus cells support their oocyte not only through mechanical protection but also with a close bidirectional exchange of metabolites. Analysis of the oocytes cumulus gives the opportunity to explore non-invasively oocytal well-being and quality. In vitro maturation (IVM) is the first rate-limiting step in in vitro embryo production. Analysis of protein expression in cumulus cells around this critical step helps to explore the impact of maturation conditions and to examine an influence on maturational competence of the oocyte. The goal of this study was the comparison of the cumulus proteome of oocytes with and without maturational competence matured under in vivo and in vitro conditions. Therefore twenty cumulus samples corresponding to single oocytes were analysed. Half of the samples were matured in vivo and the other half in vitro. For each maturation group, cumulus from oocytes matured successfully (SM; n=5) and failed to mature (FM; n=5) were analysed.
Project description:The maturation of an oocyte, the female gamete, during folliculogenesis is highly dependent on the molecular interaction with the somatic cells. Here we generated transcriptome data of single oocytes and the surrounding cumulus cells from antral follicles, and developed an analytical framework to unveil their inter-cellular communication. We identified hundreds of ligand-receptors pairs that can transduce paracrine signaling between oocyte and cumulus. Several of the ligand-coding genes expressed in oocytes and cumulus cells are also functionally associated with regulation of transcription. Ligand-coding genes expressed in oocytes or cumulus showed distinct enrichment for biological functions that are likely associated with a coordinated formation of the transzonal projections from the cumulus that reach the oocyte’s membrane. Finally, there were thousands of gene pairs with non-trivial linear co-expression pattern between oocytes and cumulus cells. Our analyses revealed a complex and functional regulatory circuit between the oocyte and surrounding cumulus cells.
Project description:Cytoplasmic and nuclear maturation of oocytes as well as interaction with the surrounding cumulus cells are important features relevant to the acquisition of developmental competence. We used brilliant cresyl blue (BCB) to distinguish oocytes with low activity of the enzyme Glucose-6-Phosphate Dehydrogenase, and thus separated fully grown (BCB+) oocytes from those in the growing phase (BCB-). The BCB+ oocytes are twice as likely to produce a blastocyst in vitro compared to BCB- oocytes (P<0.01). We analyzed mitochondrial DNA (mtDNA) copy number in single oocytes and determined that BCB- oocytes have 1.3-fold more copies than BCB+ oocytes (P=0.004). We also interrogated the transcriptome of oocytes and surrounding cumulus cells of BCB+ versus BCB- oocytes. There was no differential transcript abundance of genes expressed in oocytes, but we identified 172 genes in cumulus cells with differential transcript abundance (FDR<0.05) based on the BCB staining of their oocyte. Differential gene co-expression analysis between BCB+ and BCB- oocytes and their surrounding cumulus cells revealed dynamic coordination of transcript abundance between both compartments of the cumulus-oocyte complex. We identified a subset of genes whose co-expression in fully grown oocytes (n=75) and their surrounding cumulus cells (n=108) compose a unique profile of the cumulus-oocyte complex. In conclusion, as oocytes transition from growing to fully grown, there is an increase in the likelihood of producing a blastocyst, a reduction of mtDNA copies and no systematic variation of transcript abundance. Cumulus cells present changes in transcript abundance, which reflects in a dynamic co-expression between oocyte and cumulus cells.