Our studies focus on spindle and chromosome dynamics, and the mechanisms that ensure proper chromosome transmissions and inheritance. Several years ago we identified a kinesin-related microtubule motor protein, Ncd, that is required for normal chromosome distribution in Drosophila. Our current efforts are to determine the mechanism of Ncd function in chromosome segregation and the molecular basis of the unexpected reversed polarity of Ncd movement on microtubules, relative to kinesin.
We have localized the Ncd motor to meiotic and mitotic spindle fibers and spindle poles, and have shown that Ncd mutants exhibit highly abnormal meiotic spindles and frequent centrosome loss from mitotic spindle poles. These findings imply that the Ncd motor is needed for assembly of normal meiotic spindles and attachment of centrosomes to poles in mitotic spindles.
Using a fusion of Ncd to GFP, the jellyfish green fluorescent protein, we have followed spindle dynamics in live oocytes and embryos. These studies have allowed us to visualize the meiotic divisions in oocytes for the first time, as well as follow the mitotic divisions in wild-type and mutant embryos. Microtubule motors similar to Ncd probably exist in most or all eukaryotes, where they perform roles in meiosis and mitosis that include spindle pole formation, attaching centrosomes to spindle poles, and mediating poleward chromosome movement by sliding microtubules and kinetochores poleward.
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