... by the spindle assembly checkpoint (SAC) when chromosomes have not attached to spindle microtubules. Unattached kinetochores catalyze the formation of a diffusible APC/C CDC20 inhibitor that comprises BUBR1 (also known as BUB1B), BUB3, MAD2 (also known as MAD2L1) and a second molecule of CDC20. Recruitment...

...Jonathan W. Armond; Elina Vladimirou; Muriel Erent; Andrew D. McAinsh; Nigel J. Burroughs ABSTRACT 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...

... null mutation. NudE can associate with kinetochores, spindles and the nuclear envelope. In nudE mutant brain mitotic cells, centrosomes are often detached from the poles. Moreover, the centrosomes of mutant primary spermatocytes do not migrate from the cell cortex to the nuclear envelope, establishing...

... and thereby release telomere-containing arm segments (called acentric fragments because they lack kinetochores) from segregating chromosomes. Analysis of the movement of acentric fragments after their release provided clear evidence that previously conjoined partners were indeed tethered at their telomeres...

... to resist them. Recent evidence that the microtubule-stabilizing drugtaxol causes monooriented chromosomes to move to the periphery of an aster ( Ault et al., 1991 ) are consistent with this interpretation. An alternative hypothesis might pit opposite-acting motor molecules at the kinetochores (e.g. kinesin...

...Julia A. M. Swedak; Cynthia Leggiadro; Arthur Forer ABSTRACT We used an ultraviolet microbeam to irradiate kinetochores of chromosomes in crane-fly spermatocytes. We used one of two doses, low (0.106 ergμm −2 ) or high (0.301 ergμm −2 ), and then studied the microtubules in those spindles using...

... kinetochore microtubules was produced by incubating cells in 17 μ M nocodazole to block microtubule assembly. Under these conditions the spindle poles moved towards the metaphase plate at a rate of 3.6±0.4 μ mmin −1 (n=3). On the basis of anti-tubulin immunofluourescent staining of cells fixed after...

...Paula Wilson; Arthur Forer ABSTRACT Areas of reduced birefringence (ARBs) produced by ultraviolet microbeam irradiation are areas of depolymerized microtubules. ARBs probably move poleward either by microtubule subunit addition at the kinetochore and loss at the pole, or by microtubule subunit...