Chromosome flexion: potential for assessing the state of spindle assembly.

A novel measurement, that of chromosome flexion, has been used to assess the degree of spindle polymerization at metaphase in human lymphocytes. It was found that this measurement showed a highly repeatable quantitative response to nocodazole exposure. Thus this measurement could be used to assess the potential for chemicals to depolymerize spindles. Under controlled conditions, individual differences were observed between the subjects which might be related to their age. However, the response to nocodazole-induced spindle depolymerization, as measured by flexion, was uniform for all subjects. 4 chemicals reported to induce aneuploidy in mammalian cells were used in a flexion assay. Only substances known to depolymerize microtubules reduced chromosome flexion.