Research Article

Roscovitine in combination with calcium ionophore induces oocyte activation through reduction of M-phase promoting factor activity in mice

Tomomi Iba^a2, Yuya Yano^a3, Mayumi Umeno^a4, Kenji Hinokio^a5, Akira Kuwahara^a5, Minoru Irahara^a5, Shuji Yamano^a6 and Toshiyuki Yasui^a1 c1

^a1 Department of Reproductive Technology, Course of Human Development, Human Development and Health Science, Institute of Health Biosciences, The University of Tokushima Graduate School, 3–18–15 Kuramoto, Tokushima 770–8503, Japan.

^a2 Graduate School of Health Science, The University of Tokushima Graduate School, 3–18–15 Kuramoto, Tokushima 770-8503, Japan.

^a3 Department of Obstetrics and Gynecology, Tokushima University Hospital, 3-18-15 Kuramoto, Tokushima 770-8503, Japan.

^a4 Biomedical Laboratory Sciences, Institute of Health Biosciences, The University of Tokushima Graduate School, 3-18-15 Kuramoto, Tokushima 770-8503, Japan.

^a5 Department of Obstetrics and Gynecology, Institute of Health Biosciences, The University of Tokushima Graduate School, 3-18-15 Kuramoto, Tokushima 770-8503, Japan.

^a6 Department of Reproductive Technology, Institute of Health Biosciences, The University of Tokushima Graduate School, 3-18-15 Kuramoto, Tokushima 770-8503, Japan.

Summary

The aim of the present study was to determine oocyte activation and change in M-phase promoting factor (MPF) activity induced by treatment with calcium ionophore and roscovitine in comparison with those induced by treatment with roscovitine alone and treatment with calcium ionophore and puromycin in mice. Freshly ovulated oocytes obtained from 6–8-week-old mice were divided into five groups (no activation treatment; 5 μM calcium ionophore A23187; 50 μM roscovitine; 5 μM calcium ionophore and 10 μg/ml puromycin; and 5 μM calcium ionophore and 50 μM roscovitine) and were incubated for 6 h. Oocyte activation, assessed by morphological changes, and changes in MPF activity in the five groups at 0, 2, 4 and 6 h of incubation were examined. Activated oocytes were defined as oocytes with at least one pronucleus. Oocytes treated with roscovitine alone were not activated during the 6-h incubation period. All of the oocytes in the calcium ionophore with puromycin group and in the calcium ionophore with roscovitine group were activated. The percentage activity of MPF in oocytes treated with roscovitine alone was decreased after 2 h and increased after 4 h of incubation. The percentage activity of MPF in oocytes treated with calcium ionophore and roscovitine was significantly decreased with suppression of MPF activity being maintained for 6 h, and this change was similar to that in oocytes treated with calcium ionophore and puromycin. Roscovitine with calcium ionophore is effective for induction of oocyte activation through suppression of MPF activity in mice.

(Received May 09 2011)

(Accepted August 16 2011)

(Online publication October 06 2011)

Keywords:

• Calcium ionophore;
• MPF;
• Oocyte activation;
• Roscovitine

Correspondence:

^c1 All correspondence to: Toshiyuki Yasui. Department of Reproductive Technology, Course of Human Development, Human Development and Health Science, Institute of Health Biosciences, The University of Tokushima Graduate School, 3–18–15 Kuramoto, Tokushima 770–8503, Japan. Tel: +81 88 633 9023. Fax: +81 88 631 2630. e-mail: yasui@medsci.tokushima-u.ac.jp