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This Article Full Text Full Text (PDF) All Versions of this Article: 74/4/691    most recent biolreprod.105.043885v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Lee, J.-H. Articles by Campbell, K. H.S. Search for Related Content PubMed PubMed Citation Articles by Lee, J.-H. Articles by Campbell, K. H.S. Agricola Articles by Lee, J.-H. Articles by Campbell, K. H.S.

Effects of Enucleation and Caffeine on Maturation-Promoting Factor (MPF) and Mitogen-Activated Protein Kinase (MAPK) Activities in Ovine Oocytes Used as Recipient Cytoplasts for Nuclear Transfer¹

Animal Development and Biotechnology Group, Division of Animal Physiology, School of Biosciences, The University of Nottingham, Sutton Bonington, Loughborough, Leicestershire LE12 5RD, United Kingdom

ABSTRACT

In general, oocytes arrested at metaphase of the second meiotic division (MII) are used as recipient cytoplasts for nuclear transfer (NT) procedures. MII oocytes contain high levels of maturation-promoting factor (MPF) and mitogen-activated protein kinase (MAPK), which cause nuclear envelope breakdown (NEBD) and premature chromosome condensation (PCC) in the transferred nucleus and have been implicated in nuclear reprogramming. However, the occurrence of NEBD and the extent of PCC are variable between individual oocytes and species and are dependent on donor cell type and cell cycle stage. Enucleation, which removes oocyte cytoplasm, may reduce MPF and MAPK activities and reduce reprogramming; conversely, increasing kinase activities may increase reprogramming. We compared the effects of enucleation of ovine oocytes at anaphase/telophase of the first meiotic division (AI-TI) and at MII. MPF and MAPK activities were maximal at MII; blind enucleation at AI-TI was more efficient than at MII and removed a smaller volume of cytoplasm. Neither protocol significantly affected the activity of either kinase and the fate of the donor nucleus; however, enucleation per se significantly reduced the occurrence of NEBD in NT embryos. Treatment with 10 mM caffeine significantly increased the activities of both kinases and the occurrence of NEBD but did not affect the frequency of development to the blastocyst stage; however, a significant increase in total cell numbers was observed. The results show that caffeine can increase MPF and MAPK activities in ovine oocytes and that this may contribute to an increased reprogramming in NT embryos.

embryo, kinases, meiosis, oocyte development, phosphatases

¹ Supported by the University of Nottingham.

² Correspondence: Keith Campbell, University of Nottingham, School of Biosciences, Sutton Bonington, Loughborough, Leicester LE12 5RD, United Kingdom. FAX: 44 115 951 6302; keith.campbell{at}nottingham.ac.uk

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