Chromatid separation independent of the spindle apparatus

The chromatid separation process has also remained mysterious. It is an autonomous process that does not directly depend on the mitotic spindle (Wilson 1925, Mazia 1961). This is most vividly seen in cells whose spindles have been destroyed by spindle poisons such as colchicine. In many organisms, in particular in plant cells, the cell cycle delay induced by colchicine is only transient and chromatids eventually split apart in the complete absence of a mitotic spindle (Mole-Bajer 1958, Rieder & Palazzo 1992) (Fig. 2). Mitosis in the presence of colchicine or colcemid (known as c-mitosis) leads to the production of daughter cells with twice the normal complement ofchromosomes. This process is routinely used for manipulating plant genomes and may contribute to the therapeutic effects of taxol in treating breast cancer.

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