Microtubules are involved in chromosome segregation, but their role in the spindle function is not well understood. Transport of particles is superimposed on chromsome movements in all types of cells. This overlooked transport is an expression of the spindle function and results in the distribution of spindle inclusions randomly but always in a statistically predicted direction/manner. Thus the behavior of particles can be used as a convenient direct probe for the microtubule function during mitosis. We propose to correlate particle transport with the spacial distribution of the spindle microtubules. Both undefined endogenous particles and defined pressure injected probes (colloidal gold particles, inert and coated with antibodies, such as antitubulin) will be analyzed. Latest technology allows us to locate single 40 nm colloidal gold particles within the cells by video enhanced light microscopy. The correlation of particle distribution with the arrangement of microtubules in the same cells will be done with immuno-methods (immuno-gold and immuno-gold-silver enhanced) and in vivo. Quantitative analysis of translocation of gold probes in controls and in experimental conditions) where only certain classes of microtubules persist, on under the influence of metabolic inhibitors), will relate particle transport to specific arrays of microtubules (kinetochore vs. non-kinetochore) and characterize the particle transport within small domains of the spindle in different stages of mitosis. Experiments will determine whether the "molecular motor" distributing particles drives also chromosomes to the poles, or is not related to the chromosome distribution. The observations on particle transport within anucleated fragments, which contain arrays of sponstaneously reorganized microtubles, will bridge directly in vitro and in vivo data necessary for the molecular understanding and control of mitosis. Our preliminary data demonstrate the feasibility of the proposed experiments, and recent improvements and developments of techniques make our system (Haemanthus endosperm) uniquely suited for the proposed studies.