Search results for "Imprinting"
showing 10 items of 124 documents
340 EPIGENETIC ANALYSIS OF DEVELOPMENTALLY IMPORTANT GENES IN BOVINE OOCYTES OF DIFFERENT ORIGINS
2010
A critical step in assisted reproductive technologies (ART) is the IVM of oocytes. The quality of the oocyte is crucial for successful fertilization and subsequent embryo development. Studies in bovine ART, and epidemiological studies in children from ART, reveal a degree of abnormal development thought to be primarily caused by aberrant DNA methylation patterns in imprinted and non-imprinted genes. Due to the inherent similarities in bovine and human preimplantation embryonic development, bovine oocyte and embryo development is increasingly being used as a model for human development. The goal of this project is to investigate the effects of specific IVM conditions on the DNA methylation …
Conserved synteny of mammalian imprinted genes in chicken, frog, and fish genomes
2006
Conservation of synteny of mammalian imprinted genes between chicken and human suggested that highly conserved gene clusters were selected long before these genes were recruited for genomic imprinting in mammals. Here we have applied in silico mapping of orthologous genes in pipid frog, zebrafish, spotted green and Japanese pufferfish to show considerable conservation of synteny in lower vertebrates. More than 400 million years ago in a common ancestor of teleost fish and tetrapods, ‘preimprinted’ chromosome regions homologous to human 6q25, 7q21, 7q32, 11p15, and 15q11→q12 already contained most present-day mammalian imprinted genes. Interestingly, some imprinted gene orthologues which are…
Extreme Methylation Values of Imprinted Genes in Human Abortions and Stillbirths
2010
Imprinted genes play an important role in fetal and placental development. Using quantitative bisulfite pyrosequencing assays, we determined the DNA methylation levels at two paternally methylated (H19 and MEG3) and four maternally methylated (LIT1, NESP55, PEG3, and SNRPN) imprinted regions in fetal muscle samples from abortions and stillbirths. Two of 55 (4%) spontaneous abortions and 10 of 57 (18%) stillbirths displayed hypermethylation in multiple genes. Interestingly, none of 34 induced abortions had extreme methylation values in multiple genes. All but two abortions/stillbirths with multiple methylation abnormalities were male, indicating that the male embryo may be more susceptible t…
261 INFLUENCE OF IN VITRO MATURATION ON EPIGENETIC MARKS AND GENE EXPRESSION IN BOVINE OOCYTES
2011
In cattle, in vitro maturation (IVM) of oocytes is an integral part of assisted reproduction technology. However, only 30% of in vitro matured bovine oocytes develop to the blastocyst stage after fertilization (compared with 60% for in vivo matured oocytes), indicating critical involvement of maturation conditions in the developmental competence of oocytes. Oocytes for IVF and intracytoplasmic sperm injection in humans are typically allowed to mature in vivo after superovulation because IVM is not considered to be a safe medical procedure. Several studies have shown that assisted reproduction technology involving prolonged in vitro culture of human and ruminant embryos can be associated wi…
Imprint switching on human chromosome 15 may involve alternative transcripts of the SNRPN gene
1996
Imprinting on human chromosome 15 is regulated by an imprinting centre, which has been mapped to a 100–kb region including exon 1 of SNRPN. From this region we have identified novel transcripts, which represent alternative transcripts of the SNRPN gene. The novel exons lack protein coding potential and are expressed from the paternal chromosome only. We have also identified intragenic deletions and a point mutation in patients who have Angelman or Prader–Willi syndrome due to a parental imprint switch failure. This suggests that imprint switching on human chromosome 15 may involve alternative SNRPN transcripts.
Genomic conflicts and sexual antagonism in human health: Insights from oxytocin and testosterone
2015
We review the hypothesized and observed effects of two of the major forms of genomic conflicts, genomic imprinting and sexual antagonism, on human health. We focus on phenotypes mediated by peptide and steroid hormones (especially oxytocin and testosterone) because such hormones centrally mediate patterns of physical and behavioral resource allocation that underlie both forms of conflict. In early development, a suite of imprinted genes modulates the human oxytocinergic system as predicted from theory, with paternally inherited gene expression associated with higher oxytocin production, and increased solicitation to mothers by infants. This system is predicted to impact health through the i…
Genomic imprinting and neurodevelopment
2021
Abstract During mammalian development, most genes are equally expressed from both the maternal and the paternal alleles. However, a minority of genes known as “imprinted genes’” are expressed or silenced from either the maternal or the paternal homologue, resulting functionally monoallelic. This process known as “genomic imprinting” is essential for normal development and shows tissue and developmental-stage specificity, suggesting a key role in gene dosage fine-tuning. Furthermore, genomic imprinting is highly prevalent in the brain, and many genes with a key role in pre- and postnatal neurodevelopment are expressed in a parent-of-origin specific manner in the central nervous system. This …
Screening of oxazepine indole enantiomers by means of high performance liquid chromatography with imprinted polymer stationary phase.
2004
Chromatographic enantiomer separations of different oxazepine indole derivatives were performed using a molecularly imprinted polymer. A 5aR,12R,13S-trans-6,6-dimethyl-12,13-dihydro-6H-5a, 1 3-methanoindolo[2,1-b][1,3]naphthoxazepine-12-carboxamide enantiomerderivative was used as a template and the resultant polymer has shown enantiomer recognition for series of template related compounds. The mechanistic description of the chiral discrimination process is scrutinised, comparing the discrimination between the different conformations and substituents of the oxazepine indoles.
Health outcomes of children born after IVF/ICSI: a review of current expert opinion and literature
2014
The Sixth Evian Annual Reproduction (EVAR) Workshop Group Meeting was held to evaluate the impact of IVF/intracytoplasmic sperm injection on the health of assisted-conception children. Epidemiologists, reproductive endocrinologists, embryologists and geneticists presented data from published literature and ongoing research on the incidence of genetic and epigenetic abnormalities and congenital malformations in assisted-conception versus naturally conceived children to reach a consensus on the reasons for potential differences in outcomes between these two groups. IVF-conceived children have lower birthweights and higher peripheral fat, blood pressure and fasting glucose concentrations than …
Ovulation induction and epigenetic anomalies
2013
In this systematic review of ovulation induction and epigenetic control, studies mainly done in the mouse model highlight how hormone treatments may be prejudicial to the epigenetic reprogramming of gametes as well as early embryos. Moreover, the hormone protocols used in assisted reproduction may also modify the physiologic environment of the uterus, a potential link to endometrial epigenetic disturbances. At present, the few available data in humans are insufficient to allow us to independently determine the impact of a woman's age and infertility problems and treatment protocols and hormone doses on such processes as genomic imprinting.