| Budget Amount *help |
¥4,550,000 (Direct Cost: ¥3,500,000、Indirect Cost: ¥1,050,000)
Fiscal Year 2010: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
Fiscal Year 2009: ¥2,860,000 (Direct Cost: ¥2,200,000、Indirect Cost: ¥660,000)
|
|---|
| Research Abstract |
In mammals, a sperm-induced intracellular Ca^<2+> signal ([Ca^<2+>]i) mediates both exit of meiosis and oocyte activation during fertilization. Recently, it was demonstrated in mouse oocytes that the phosphorylation levels of inositol 1,4,5 trisphosphate receptor type1 (IP_3R1), the channel responsible for Ca^<2+> release and oscillations during fertilization, changed during maturation and fertilization (Ito et al., 2008, Dev. Biol). However, kinetics of IP3R1 is not well understood in other species, especially domestic species which have low developmental ability of oocytes when intracytoplasmic sperm injection (ICSI) and somatic cell nuclear transfer (SCNT) are applied. Therefore, we examined the expression, phosphorylation and localization of IP_3R1 during in vitro maturation of pig oocytes. Here, our present study shows that expression of IP_3R1 protein did not change during maturation, although the phosphorylation status of the receptor was dramatically upregulated beyond germinal vesicle break down (GVBD). At the GV stage, IP_3R1 was observed throughout the cytoplasm. Following oocyte maturation, concentration of IP_3R1 protein at the cortex of the oocyte was confirmed. In matured oocytes, large clusters of IP_3R1 were formed in the cortex of the oocyte except in a ring-shaped band of cortex adjacent to the spindle. Taken together, our results show that IP_3R1 undergoes dynamic phosphorylation and localization during maturation and this might underlie the generation of oscillations at fertilization. Our findings will contribute to improve the efficiency of ICSI and SCNT in domestic species.
|
