Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.662647
Title: The effect of oestrogens and androgens on mammalian oocyte maturation
Author: Swales, A.
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 2006
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Abstract:
Exposure to raised steroid levels in culture had a significant effect on the global DNA methylation levels of oocytes. Although, no alterations in gene expression were previously identified this did not rule out the possibility that the observed changes to DNA methylation levels were the result of an effect on DNMT proteins. To begin investigating this, the localisation of DNMT1o was assessed after exposure to high levels of androgens and oestrogens. Under physiological conditions the DNMT1o protein is present in the nucleus in growing oocytes and translocates to the cytoplasm as maturation progresses. Steroid exposure was found to alter the localisation profile of DNMT1o, making this a candidate mechanism by which the global DNA methylation levels are influenced by raised androgens and oestrogens. The mechanisms controlling genomic imprinting during oocyte and embryo development are still being investigated. An increased understanding of genomic imprinting during development has been achieved through analysis of the gametes, embryos and offspring of mice with null mutations for Dnmt or Mbd genes. Although, Mbd2-/- mice have been reported to have a reduced litter size, the cause of this maternal effect is currently unknown. This study did not find any significant difference between maternal genotypes in the number of oocytes ovulated, fertilisation rate or percentage of 2-cell embryos developing to the blastocyst stage during IVF. Thus, the observed phenotype of small litter size may not be the result of impaired oocyte maturation or early embryo development occurring in the absence of MBD2. The increasing use of assisted reproductive techniques means that a full understanding of the role of the environment on oocyte developmental competence is vital.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.662647  DOI: Not available
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