-210 Nottingham - Nottingham eTheses - The University of Nottingham

involves changes in the phosphorylation of various specific proteins. One of those is
MPF which leads to GVBD. Porcine oocytes require protein synthesis during the first
meiotic division. Kubelka et al. (1995) also reported 10 µg/ml CHX for 24 h of
culture prevented M-phase-associated increase in histone H1 kinase activity and
GVBD during the first meiotic division of porcine oocytes, although the condensation
of chromatin was not influenced. So CHX could block the synthesis of those proteins
and influence the nuclear and cytoplasmic maturation of oocytes.
Oocyte meiotic resumption is associated with decreased concentration of intracellular
cAMP (Tsafriri et al., 1983; Eppig and Downs, 1984; Schultz, 1991; Downs, 2002).
In this study, it was reported for the first time that cAMP proved to be more effective
in synchronising porcine oocyte maturation and more matured oocytes were obtained
in a shorter time window and at 44 hpm than CHX. Also, there were no visual
differences between control and cAMP group. The expansion of cumulus cells of
cAMP treated oocytes could be seen especially after 36 hpm. Kim et al. (2008)
reported that synchronising meiotic resumption by cAMP analogue, dbcAMP
treatment improved the developmental capacity and embryonic qualities of IVF and
SCNT embryos. This showed the potential of cAMP in synchronising porcine oocytes
to improve the development.
To gain an insight into the parthenogenetic development of porcine synchronised
oocytes by CHX and cAMP, a parthenogenetic activation system was developed (with
the frequency of blastocyst formation 28.3 ± 11.4% and total cell number 36.1 ± 3.3)
in the experiments presented in Chapter 4. No significant differences of cleavage
(81.4 ± 11.6% and 84.5 ± 5.7%, respectively) and parthenogenetic development (the
frequencies of blastocyst formation, 27.1 ± 5.7% and 32.8 t 5.3%, respectively)
existed between CHX and cAMP treated oocytes based on careful selection prior to
Parthenogenetic activation. According to greater expansion of the cumulus cells of the
COCs, the efficiency for synchronisation of porcine oocyte maturation and
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