title: Light-microscopic observations of individual microtubules reconstituted from brain tubulin.
abstract: The course of polymerization of individual brain microtubules could be observed with a light microscope employing dark-field illumination. Statistical analysis of the increase in microtubule length during the polymerization was in accordance with the time course of viscosity change of the tubulin solution. After a plateau level in viscosity was attained, there was no significant change in histograms showing length distribution. These observations were confirmed with fixed and stained microtubules, using a phase-contrast microscope. Observations with dark-field illumination revealed that reconstituted microtubules depolymerized and disappeared immediately upon exposure to buffer containing CaCl2 or sulphydryl reagents such as p-chloromercuriphenyl sulphonic acid (PCMPS) and p-chloromercuribenzoic acid (PCMB). They were also cold-labile. The growth of heterogeneous microtubules which were assembled by mixing purified tubulin dimers with ciliary outer fibres could also be followed with these optical systems.
mesh_terms: D002731:4-Chloromercuribenzenesulfonate / Q000494:pharmacology; D001921:Brain; D002122:Calcium Chloride / Q000494:pharmacology; D002729:Chloromercuribenzoates / Q000494:pharmacology; D002923:Cilia / Q000648:ultrastructure; D006023:Glycoproteins / Q000378:metabolism*; D008870:Microtubules / Q000187:drug effects / Q000648:ultrastructure*; D013768:Tetrahymena; D014404:Tubulin / Q000378:metabolism*
chemical_list: D002729:Chloromercuribenzoates; D006023:Glycoproteins; D014404:Tubulin; D002731:4-Chloromercuribenzenesulfonate; D002122:Calcium Chloride