REAL-TIME OBSERVATION OF MICROTUBULES ATTACHED TO MICROTUBULE ORGANIZING CENTERS INVITRO

The dynamics and organization of microtubules associated with axonemes and kinetochores in vitro were visualized using video microscopy tech niques. Microtubules attached either at the ends of axonemes or to mit otic chromosomes behave according to dynamic instability in our condit ions. Microtubules attached to kinetochores showed lower rates of elon gation and shortening than those nucleated by axonemes in the same con ditions. In addition, elementary bundles of microtubules appeared spon taneously in association with kinetochores, with microtubules elongati ng along previously attached microtubules at even lower rates. Such si de interactions, either spontaneous or stabilized by factors such as M APs, might affect microtubule dynamics directly.