Abstract
Vol.17 No.1
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Effect of Oocyte Aging on Parthenogenetic Activation with Cycloheximide and Alteration of the Activity of Maturation Promoting Factor during Aging of Bovine Oocytes
JMOR, 17(1) 35-41, 2000
DOI: 10.1274/jmor.17.35
DOI: 10.1274/jmor.17.35
This study was carried out to examine the underlying mechanism for the high susceptibility of bovine aged oocytes to activation stimulus. The oocytes were matured for 21, 27, 33, and 39 h and were then parthenogenetically activated with different concentrations of cycloheximide (CHX); their activation rates were then assessed. Additionally, the p34cdc2 kinase activities in oocytes matured for different time periods were determined. The activation rates of oocytes treated with CHX increased with oocyte aging. In oocytes cultured for as long as 39 h in maturation medium, the treatment led to maximal activation rate of oocytes even in those with the lowest concentration of CHX. The p34cdc2 kinase activity in oocytes decreased progressively with prolonged incubation time and the activity of the oocytes cultured for 39 h was approximately 40% of that of oocytes cultured for 21 h. In conclusion, the sensitivity of bovine oocytes to activation stimulus increases during in vitro aging; also, the time dependent decline in the capacity of oocytes to synthesize the regulatory protein required for maintaining MII stage may contribute to a high susceptibility of aged oocytes to protein synthesis inhibitor (activation stimulus).
