Oocyte maturation in mammals follows a highly conserved pattern of release from arrest through to the extrusion of the first polar body and formation of the second metaphase spindle. Oscillations in cytoplasmic @entity460 concentration precede the events of maturation in many species. These @entity460 ions interact with and activate @entity460 -binding proteins, including calmodulin, within the cell. Thus, it was of interest to us to examine whether @entity460 acted through calmodulin in the initial stages of maturation in @entity95 oocytes or whether calmodulin was required for continuation through metaphase I no to metaphase II. Using the calmodulin inhibitor W-7 we found a significant (p < 0.05) decrease in the percentage of oocytes that underwent germinal vesicle breakdown. Calmidazolium did not prevent germinal vesicle breakdown; however, it caused a significant (p < 0.05) decrease in the proportion of oocytes with fully elaborated spindles and @entity1311 -induced cytoplasmic asters. Both inhibitors caused a significant (p < 0.05) reduction in the proportion of oocytes that extruded their first polar bodies. The kinase inhibitor @entity20119 caused a significant reduction in the proportion of oocytes with spindles and condensed chromatin, indicating the necessity for phosphorylation events in the resumption of meiosis. In @entity95 oocytes calmodulin may play a role in the release from prophase arrest, and it is necessary for spindle preservation and continuation through metaphase I to metaphase II. The varying effects of the two inhibitor stems from their different binding sites on the calmodulin molecule thus causing a differential effect on its downstream effectors.

Oocyte maturation in XXXX : effects of calmodulin inhibitors.

@entity20119 :: ('MESH:C001020', 'Chemical') :: ['6-DMAP'] @entity1311 :: ('MESH:D017239', 'Chemical') :: ['taxol'] @entity95 :: ('9986', 'Species') :: ['rabbit'] @entity460 :: ('MESH:D002118', 'Chemical') :: ['calcium']
@entity95 :: (9986,Species) :: ['rabbits']
