Presence of actin during chromosomal movement

Abstract

Actin was shown to be present in the nucleoli, kinetochore and centriolar regions, and in the mitotic spindle of rat kangaroo cells which were stained with fluorescently labeled heavy meromyosin. The actin in the spindle is confined to the fibers that connect the chromosomes with the centriolar region. Actin was not present in astral fibers, in the continuous spindle fibers that connect the poles, or in non kinetochore regions of the chromosomes. The specific localization of actin in chromosomal spindle fibers suggests an actin myosin interaction as the force producing mechanism for chromosomal movement.