High developmental competence of pig oocytes after meiotic inhibition with a specific M-phase promoting factor kinase inhibitor, butyrolactone I.
Butyrolactone I specifically inhibits M-phase promoting factor activation and prevents the resumption of meiosis. These experiments were conducted to examine effects of butyrolactone I on pig oocytes in a serum-free maturation system. The first experiment was conducted to determine the effect of butyrolactone I (0-100 microM) on nuclear maturation. At concentrations of > or =12.5 microM, germinal vesicle breakdown was prevented in >90% of the oocytes after 24 h of culture. In the second experiment, the kinetics of in vitro maturation of butyrolactone I-treated oocytes was investigated. Oocytes were treated with 0 or 12.5 microM butyrolactone I and FSH for 20 h and then cultured with LH in the absence of butyrolactone I for another 24 h. Fewer butyrolactone I-treated oocytes reached MII stage at 36 h compared with controls (5.8% vs. 62.4%, P < 0.01). However, by 44 h, 83.4% of butyrolactone I-treated oocytes reached MII compared with 88.6% of controls. In the third experiment, butyrolactone I-treated oocytes were fertilized and cultured in vitro. No differences (P > 0.05) were found between controls and treated groups in cleavage rate, blastocyst rate, or mean number of cells per blastocyst. Effects of butyrolactone I on mitogen-activated protein kinase activation and localization of microfilaments and active mitochondria were examined by Western blot analysis and laser scanning confocal microscopy, respectively. The results suggested that although butyrolactone I reversibly inhibited germinal vesicle breakdown and mitogen-activated protein kinase activation, it did not affect mitochondrial and microfilament dynamics. Butyrolactone I is a potent inhibitor of nuclear maturation of porcine oocytes, and the inhibition is fully reversible.
Wu
Guang-Ming
GM
Department of Animal Sciences, University of Missouri-Columbia, Columbia, MO 65211, USA.
Sun
Qing-Yuan
QY
Mao
Jiude
J
Lai
Liangxue
L
McCauley
Tod C
TC
Park
Kwang-Wook
KW
Prather
Randall S
RS
Didion
Brad A
BA
Day
Billy N
BN
D015107:4-Butyrolactone / Q000031:analogs & derivatives* / Q000494:pharmacology*; D008841:Actin Cytoskeleton / Q000378:metabolism / Q000648:ultrastructure; D000818:Animals; D002467:Cell Nucleus / Q000502:physiology / Q000648:ultrastructure; D002843:Chromatin / Q000378:metabolism / Q000648:ultrastructure; D003593:Cytoplasm / Q000502:physiology / Q000648:ultrastructure; D005314:Embryonic and Fetal Development / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005260:Female; D005307:Fertilization in Vitro / Q000187:drug effects; D016200:Maturation-Promoting Factor / Q000037:antagonists & inhibitors / Q000378:metabolism*; D008540:Meiosis / Q000187:drug effects*; D018613:Microscopy, Confocal; D008928:Mitochondria / Q000378:metabolism / Q000648:ultrastructure; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D009865:Oocytes / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D010766:Phosphorylation; D013552:Swine
D002843:Chromatin; D004791:Enzyme Inhibitors; C082868:butyrolactone I; D016200:Maturation-Promoting Factor; D020928:Mitogen-Activated Protein Kinases; D015107:4-Butyrolactone