Change in the nuclear phase and kinase activity during in vitro maturation of the porcine oocytes

It aimed at investigating a relation with maturity of the cytoplasm which made the index the maturation promoting factor (MPF) and mutagens activated protein (MAP) kinase activity which participate in nuclear and the cell of the porcine oocytes. Changes in the nuclear phase of porcine oocytes were examined in 4 time intervals during maturation, beginning with the in vitro culture stage and ending 48 hours after cultivation. We also examined the activity of histone H1 kinase (H1k) and MAP kinase (MAPk) which are markers for the MPF and their correlation to the nuclear phase transition and culture time. Since activity might change delicately when many ova are required to measure kinase activity and the sample changed, the activity of both kinase of the same sample was measured at once. The results showed that at 0hr, the start of the culture process, all ova were at the germinal vesicle stage (GV) of the nuclear phase. At 12hr, most ova were still at the GV stage of the nuclear phase, however the incidence rate began to decrease at 16hr, and at 24hr decreased even more until at 32hr it was almost nil. A decrease in the percentage of nuclear phase ova appeared 16 hours after the start of the culture process. This period was designated as the first metaphase (M1) and by 24hr, about 80% of the ova were at the M1 stage of the nuclear phase. The ratio during the anaphase to the telophase (A1-T1) of the nuclear phase was 4.2% and 18.2% respectively with the times for each recognized at 28hr and 32hr. The second metaphase (M2) of the overacts nuclear phase was designated at 24hr, however at 32hr it increased to 23.4% and at 36hr began to increase more rapidly to 73.9% reaching its highest level of 86.4% at 48hr. H1k activity progressed from a low level at the GV stage, increasing during dyakines (Pro M1) and continuing to rise during the initial M1 stage from 16hr to 20hr until it reached its highest level at 24hr and 28hr of the M1 stage. At 32hr when the M2 stage of the nuclear phase began, it momentarily decreased, but rose again at 36hr which was the highest level for the M2 stage and continued at this fixed rate. At 12hr, MAPk activity was low just as H1k activity was at the same time, but began to increase during the ProM1 and M1 stage, or from 16hr to 20hr, reaching its highest level between 24hr and 28hr and maintaining this level until 48hr. The above results clarify the necessity for a 36 hour-culture for in vitro maturation of porcine oocytes and that ch