The project will investigate the nature of the mitotic motility systems that move chromosomes. The specific aim is to distinguish between and characterize the different components that collectively generate motility in the aster, and to determine which are involved in chromosome movement. The transport properties of the aster will be examined at highest microscopic resolution, and then the effects of metabolic inhibitors on the polewards and antipolewards movements will be compared with the behaviour of prometaphase chromosomes. The principal investigator will ascertain whether the higher plant spindle, with its broad open poles, shows a response similar to the contraction of prometaphase chromosomes induced in the radially organized, centric mammalian spindle by metabolic inhibitors. Similar observations on the phragmoplast may show what its transport properties have in common with astral transport. The permeabilized cell model, successful in investigating anaphase A, will now be used in attempts to reactivate prometaphase chromosome activity and astral transport. Studies will examine chromosome movement, and any concurrent microtubule disassembly,by exposing PtK cells to ATP and various analogs and inhibitors. The mechanisms responsible for chromosome movement during cell division remain one of the least understood, but important issues in cell biology. Results obtained during the course of this project, on the comparative physiology of polar and antipolar transport, should substantially contribute to our understanding of these mechanisms.
