-210 Nottingham - Nottingham eTheses - The University of Nottingham

in vitro substrates.
In pigs, Naito and Toyoda (1991) were the first to report a MPF kinase assay followed
by development of other protocols by Christmann et al. (1994), Kubelka et al. (1995),
Wehrend and Meinecke (2001), Kubelka et al. (2002), Kanayama et al. (2002), Goto
et al. (2002), Ye et al. (2003), Okada et al. (2003) and Susor et al. (2007). MAPK in
porcine oocytes was first assayed by Inoue et al. (1995).
Since the birth of "Dolly",
animal cloning from somatic cells has been achieved in
many species. Although exposure of donor nuclei to the egg cytoplasm can reverse the
process of differentiation and convert the somatic nuclei into an embryonic state, the
efficiency of successful development is still very low (Wilmut et al., 1997; Cibelli et
al., 1998; Wakayama et al., 1998). Inadequate reprogramming of the donor nucleus is
considered to be the principal reason for developmental failure of clones. As
discussed in Chapter 1, nuclear reprogramming of the donor nucleus is affected by a
range of biological and technical factors.
The cell cycle and quality of the recipient oocyte is a major factor contributing to the
success of SCNT. MII oocytes are generally accepted to be optimal for
reprogramming to occur and these events are most probably related either directly or
indirectly to the activities of MPF and MAPK. In these studies, porcine oocyte
maturation was manipulated in several ways in an attempt to improve somatic cloning
efficiency. To produce a more biochemically homogenous population, oocyte
maturation was synchronised (Chapter 3 and 4).
Having determined the maturation timing (particularly the optimum time point
for TI
enucleation) of porcine oocytes synchronised by cAMP and the percentage of oocytes
enucleated at TI (Chapter 4), further studies were carried out to combine TI
enucleation of porcine oocytes with subsequent treatment using caffeine to improve
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