BEHAVIOR OF CROCIDOLITE ASBESTOS DURING MITOSIS IN LIVING VERTEBRATE LUNG EPITHELIAL-CELLS

(1)Asbestos has been described as a physical carcinogen in that long t hin fibers are generally more carcinogenic than shorter thicker ones. It has been hypothesized that long thin fibers disrupt chromosome beha vior during mitosis, causing chromosome abnormalities which lead to ce ll transformation and neoplastic progression. Using high-resolution ti me lapse video-enhanced light microscopy and the uniquely suited lung epithelial cells of the newt Taricha granulosa, we have characterized for the first time the behavior of crocidolite asbestos fibers, and th eir interactions with chromosomes, during mitosis in living cells. We found that the keratin cage surrounding the mitotic spindle inhibited fiber migration, resulting in spindles with few fibers. As in interpha se, fibers displayed microtubule-mediated saltatory movements. Fiber p osition was only slightly affected by the ejection forces of the spind le asters. Physical interactions between crocidolite fibers and chromo somes occurred randomly within the spindle and along its edge. Crocido lite fibers showed no affinity toward chromatin and most encounters en ded with the fiber passively yielding to the chromosome. In a few enco unters along the spindle edge the chromosome yielded to the fiber, whi ch remained stationary as if anchored to the keratin cage. We suggest that fibers thin enough to be caught in the keratin cage and long enou gh to protrude into the spindle are those fibers with the ability to s nag or block moving chromosomes.