Polewards microtubule flux in the mitotic spindle: evidence from photoactivation of fluorescence - PubMed (original) (raw)

Polewards microtubule flux in the mitotic spindle: evidence from photoactivation of fluorescence

T J Mitchison. J Cell Biol. 1989 Aug.

Abstract

I have synthesized a novel derivative of carboxyfluorescein that is nonfluorescent, but can be converted to a fluorescent form by exposure to 365-nm light. This photoactivable, fluorescent probe was covalently attached to tubulin and microinjected into mitotic tissue culture cells, where it incorporated into functional spindles. To generate a fluorescent bar across the mitotic spindle, metaphase cells were irradiated with a slit microbeam. This bar decreased in intensity over the first minute, presumably due to turnover of nonkinetochore microtubules. The remaining fluorescent zones, now presumably restricted to kinetochore microtubules, moved polewards at 0.3-0.7 microns/min. This result provides strong evidence for polewards flux in kinetochore microtubules. In conjunction with earlier biotin-tubulin incorporation experiments (Mitchison, T. J., L. Evans, E. Schulze, and M. Kirschner. 1986. Cell. 45:515-527), I conclude that microtubules polymerize at kinetochores and depolymerize near the poles throughout metaphase. The significance of this observation for spindle structure and function is discussed. Local photoactivation of fluorescence should be a generally useful method for following molecular dynamics inside living cells.

PubMed Disclaimer

Similar articles

Cited by

References

    1. J Cell Biol. 1967 Jun;33(3):713-20 - PubMed
    1. Adv Cell Biol. 1971;2:225-97 - PubMed
    1. Chromosoma. 1976 Mar 10;54(4):363-85 - PubMed
    1. Anal Biochem. 1976 May 7;72:248-54 - PubMed
    1. J Mol Biol. 1976 Nov;108(1):139-50 - PubMed

Publication types

MeSH terms

Substances

LinkOut - more resources