Cell Biology

Chromosome-Free Spindles

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Science  18 Apr 2003:
Vol. 300, Issue 5618, pp. 397
DOI: 10.1126/science.300.5618.397b

During mitosis, chromosomes are separated to daughter cells by the mitotic spindle, a bipolar arrangement of cellular microtubules. The relative contribution of the chromosomes themselves to spindle formation and dynamics has been the subject of debate.

Now Bucciarelli et al. have been able to observe spindle dynamics in a chromosome-free environment, while still looking at a living intact cell system. Using Drosophila mutants that produce secondary spermatocytes that lack chromosomes, morphologically normal spindles were observed in the absence of chromosomes. The anucleate cells possessed centrosomes that could act as spindle poles generating microtubule asters and spindles that underwent anaphase, and telophase-like elongation and disassembly. After the chromosomeless telophase, the cells underwent normal cytokinesis and cleavage. One of the proteins that would usually accumulate on partitioning chromosomes, aurora B kinase, still accumulated at the midzone, implying that chromosomes are not required for its localization to the central spindle.—SMH

J. Cell Biol. 160, 993 (2003).

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