/manager/Index ${session.getAttribute("locale")} 5 Effect of aging on superovulation efficiency, aneuploidy rates, and sister chromatid cohesion in mice aged up to 15 months /manager/Repository/uon:21537 Tue 11 Aug 2020 15:03:41 AEST ]]> The Aurora kinase inhibitor ZM447439 accelerates first meiosis in mouse oocytes by overriding the spindle assembly checkpoint /manager/Repository/uon:11469 Sat 24 Mar 2018 08:11:09 AEDT ]]> Essential role of protein phosphatase 2A in metaphase II arrest and activation of mouse eggs shown by okadaic acid, dominant negative protein phosphatase 2A, and FTY720 /manager/Repository/uon:18116 2+-mediated activation of the anaphase-promoting complex/cyclosome (APC/C). Although the loss in activity of the M-phase kinase CDK1 is known to be an essential downstream event of this process, the contribution of phosphatases to arrest and meiotic resumption is less apparent, especially in mammals. Therefore, we explored the role of protein phosphatase 2A (PP2A) in mouse eggs using pharmacological inhibition and activation as well as a functionally dominant-negative catalytic PP2A subunit (dn-PP2Ac-L199P) coupled with live cell imaging. We observed that PP2A inhibition using okadaic acid induced events normally observed at fertilization: degradation of the APC/C substrates cyclin B1 and securin resulting from loss of the APC/C inhibitor Emi2. Although sister chromatids separated, chromatin remained condensed, and polar body extrusion was blocked as a result of a rapid spindle disruption, which could be ameliorated by non-degradable cyclin B1, suggesting that spindle integrity was affected by CDK1 loss. Similar cell cycle effects to okadaic acid were also observed using dominant-negative PP2Ac. Preincubation of eggs with the PP2A activator FTY720 could block many of the actions of okadaic acid, including Emi2, cyclin B1, and securin degradation and sister chromatid separation. Therefore, in conclusion, we used okadaic acid, dn-PP2Ac-L199P, and FTY720 on mouse eggs to demonstrate that PP2A is needed to for both continued metaphase arrest and successful exit from meiosis.]]> Sat 24 Mar 2018 08:04:35 AEDT ]]> Increased zona pellucida thickness and meiotic spindle disruption in oocytes from cigarette smoking mice /manager/Repository/uon:17909 Sat 24 Mar 2018 07:56:41 AEDT ]]> Reduced chromosome cohesion measured by interkinetochore distance is associated with aneuploidy even in oocytes from young mice /manager/Repository/uon:20166 Sat 24 Mar 2018 07:51:44 AEDT ]]>