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Role of Spo13 during Meiosis in Saccharomyces cerevisiae
  • julie
julie
Max Planck Institute of Biochemistry

Corresponding Author:[email protected]

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Abstract

Accurate chromosome segregation requires that all kinetochores attach to spindle microtubules in a tension-generating manner before sister chromatid cohesion is destroyed at entry into anaphase. In both mitosis and meiosis, kinetochore-microtubule attachments are monitored by the spindle-assembly checkpoint (SAC): kinetochores that fail to generate tension or lack microtubules activate a signalling cascade that prevents the activation of APC/C-Cdc20. However the first meiotic division drastically differs from Mitosis and Meiosis II as it segregates homologous chromosomes and not sister chromatids. How the SAC can distinguish between monopolar and bipolar attachment remains unknown; but our results show that biorientation of chromosomes in meiosis I activates the SAC, therefore delaying the cells in metaphase I. Our aim is to understand in which way the SAC pathway is modified to recognize monopolar attachment as correct in Meiosis I. Intriguingly, we found that in absence of the meiosis-specific protein Spo13, the SAC remains abnormally active, causing a dramatic delay in metaphase I. Moreover, we confirmed that SAC inactivation rescue spo13\textDelta\ absence of second division. Further investigation shows that this phenotype is independent of Spo13 function in monopolar attachment. An attractive possibility is that Spo13 might directly regulate the SAC.