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Updated: Feb 7, 2026

Meiotic Spindle Assessment in Mouse Oocytes by siRNA-mediated Silencing
Published on: October 11, 2015
Spindle tubulin and MTOC asymmetries may explain meiotic drive in oocytes
Tianyu Wu1, Simon I R Lane2,3, Stephanie L Morgan1
1Biological Sciences, Faculty of Natural and Environmental Sciences, University of Southampton, Southampton, SO17 1BJ, UK.
Abstract:
In the first meiotic division (MI) of oocytes, the cortically positioned spindle causes bivalent segregation in which only the centre-facing homologue pairs are retained. 'Selfish' chromosomes are known to exist, which bias their spindle orientation and hence retention in the egg, a process known as 'meiotic drive'. Here we report on this phenomenon in oocytes from F1 hybrid mice, where parental strain differences in centromere size allows distinction of the two homologue pairs of a bivalent. Bivalents with centromere and kinetochore asymmetry show meiotic drive by rotating during prometaphase, in a process dependent on aurora kinase activity. Cortically positioned homologue pairs appear to be under greater stretch than their centre-facing partners. Additionally the cortex spindle-half contain a greater density of tubulin and microtubule organising centres. A model is presented in which meiotic drive is explained by the impact of microtubule force asymmetry on chromosomes with different sized centromeres and kinetochores.
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