Several recent models for spindle length regulation propose an elastic pole to pole spindle matrix that is sufficiently strong to bear or antagonize forces generated by microtubules and microtubule motors. We tested this hypothesis using microneedles to skewer metaphase spindles in Xenopus laevis egg extracts. Microneedle tips inserted into a spindle just outside the metaphase plate resulted in...

The combination of multiple dye-DNA interactions, a fluorescence digital imaging system with a scientific CCD camera, and multivariate image analysis allows the rapid karyotyping of fluorescent human metaphase chromosome spreads. Chromosomes are stained with the bisbenzimidazole dye Hoechst 33342 and chromomycin A3, a dye pair used frequently in bivariate flow analysis and sorting of metaphase ...

Kinetochores regulate the dynamics of attached microtubule bundles (kinetochore-fibres, K-fibres) to generate the forces necessary for chromosome movements in mitosis. Current models suggest that poleward-moving kinetochores are attached to depolymerising K-fibres and anti-poleward-moving kinetochores to polymerising K-fibres. How the dynamics of individual microtubules within the K-fibre relat...

Mitosis requires dynamic attachment of chromosomes to spindle microtubules. This interaction is mediated largely by kinetochores. During prometaphase, forces exerted at kinetochores, in combination with polar ejection forces, drive congression of chromosomes to the metaphase plate. A major question has been whether kinetochore-associated microtubule motors play an important role in congression....

Centromere positions on the metaphase plate of 48 root-tip cells of four grass species were analysed using metaphases reconstructed from electron micrographs of serial thin sections. Centromere alignment was almost perfect on a plane in 15 untreated metaphases of cereals where 2n = 14; only 2% of the total variance in centromere position was out of the plane of the metaphase plate. In 23 simila...