UNASSIGNED: In oocytes, where centrosomes are absent, the chromosomes direct the assembly of a bipolar spindle. Interactions between chromosomes and microtubules are essential for both spindle formation and chromosome segregation, but the nature and function of these interactions is not clear. We have examined oocytes lacking two kinetochore proteins, @entity68759 and @entity68760 , and a centromere-associated motor protein, @entity68761 , to characterize the impact of kinetochore-microtubule attachments on spindle assembly and chromosome segregation in @entity238 oocytes. We found that the initiation of spindle assembly results from chromosome-microtubule interactions that are kinetochore-independent. Stabilization of the spindle, however, depends on both central spindle and kinetochore components. This stabilization coincides with changes in kinetochore-microtubule attachments and bi-orientation of homologs. We propose that the bi-orientation process begins with the kinetochores moving laterally along central spindle microtubules towards their minus ends. This movement depends on @entity68760 , can occur in the absence of @entity68759 , and is antagonized by plus-end directed forces from the @entity68761 motor. End-on kinetochore-microtubule attachments that depend on @entity68759 are required to stabilize bi-orientation of homologs. A surprising finding was that @entity68760 but not @entity68759 is required for co-orientation of sister centromeres at meiosis I. Together, these results demonstrate that, in oocytes, kinetochore-dependent and -independent chromosome-microtubule attachments work together to promote the accurate segregation of chromosomes.

Lateral and End-On Kinetochore Attachments Are Coordinated to Achieve Bi-orientation in XXXX Oocytes.

@entity238 :: ('7227', 'Species') :: ['Drosophila'] @entity68760 :: ('40300(Tax:7227)', 'Gene') :: ['SPC105R'] @entity68761 :: ('53561(Tax:7227)', 'Gene') :: ['CENP-E'] @entity68759 :: ('32316(Tax:7227)', 'Gene') :: ['NDC80']
@entity238 :: (7227,Species) :: ['Drosophila']
