Abstract
The structural and growth polarities of centrosomal and chromosomal microtubules were studied by analyzing the kinetics of growth of these microtubules and those initiated by flagellar seeds. By comparing rates of elongation of centrosomal and flagellar-seeded microtubules, we determined whether the centrosomal microtubules were free to grow at their plus ends only, minus ends ony, or at both ends. Our results show that centrosomal microtubules elongate at a rate corresponding to the addition of subunits at the plus end only. The depolymerization rate was also equivalent to that for the plus end only. Chromosomal microtubule elongation was similar to the centrosome-initiated growth. Since the data do not support the hypothesis that both ends of these spindle microtubules are able to interact with monomer in solution, then growth must occur only distal or only proximal to the organizing centers, implying tha the opposite ends in unavailable for exchange of subunits. Experiments with flagellar-seeded microtubules serving as internal controls indicated that the inactivity of the minus end could not be accounted for by a diffusible inhibitor, suggesting a structural explanation. Since there is no apparent way in which the distal ends may be capped, whereas the proximal ends are embedded in the pericentriolar cloud, we conclude that centrosomal microtubules are oriented with their plus ends distal to the site of nucleation. A similar analysis for chromosomal microtubules suggests that they too must be oriented with their plus ends distal to the site of initiation.
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Selected References
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- Allen C., Borisy G. G. Structural polarity and directional growth of microtubules of Chlamydomonas flagella. J Mol Biol. 1974 Dec 5;90(2):381–402. doi: 10.1016/0022-2836(74)90381-7. [DOI] [PubMed] [Google Scholar]
- Bajer A. S. Interaction of microtubules and the mechanism of chromosome movement (zipper hypothesis). 1. General principle. Cytobios. 1973 Nov;8(31):139–160. [PubMed] [Google Scholar]
- Bergen L. G., Borisy G. G. Head-to-tail polymerization of microtubules in vitro. Electron microscope analysis of seeded assembly. J Cell Biol. 1980 Jan;84(1):141–150. doi: 10.1083/jcb.84.1.141. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Borisy G. G., Marcum J. M., Olmsted J. B., Murphy D. B., Johnson K. A. Purification of tubulin and associated high molecular weight proteins from porcine brain and characterization of microtubule assembly in vitro. Ann N Y Acad Sci. 1975 Jun 30;253:107–132. doi: 10.1111/j.1749-6632.1975.tb19196.x. [DOI] [PubMed] [Google Scholar]
- Borisy G. G. Polarity of microtubules of the mitotic spindle. J Mol Biol. 1978 Sep 25;124(3):565–570. doi: 10.1016/0022-2836(78)90188-2. [DOI] [PubMed] [Google Scholar]
- Dietz R. Die Assembly-Hypothese der Chromosomenbewegung und die Veränderungen der Spindellänge während der Anaphase I in Spermatocyten von Pales ferruginea (Tipulidae, Diptera. Chromosoma. 1972;38(1):11–76. doi: 10.1007/BF00319955. [DOI] [PubMed] [Google Scholar]
- FORER A. LOCAL REDUCTION OF SPINDLE FIBER BIREFRINGENCE IN LIVING NEPHROTOMA SUTURALIS (LOEW) SPERMATOCYTES INDUCED BY ULTRAVIOLET MICROBEAM IRRADIATION. J Cell Biol. 1965 Apr;25:SUPPL–SUPPL117. doi: 10.1083/jcb.25.1.95. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Gould R. R., Borisy G. G. Quantitative initiation of microtubule assembly by chromosomes from Chinese hamster ovary cells. Exp Cell Res. 1978 May;113(2):369–374. doi: 10.1016/0014-4827(78)90377-4. [DOI] [PubMed] [Google Scholar]
- Gould R. R., Borisy G. G. The pericentriolar material in Chinese hamster ovary cells nucleates microtubule formation. J Cell Biol. 1977 Jun;73(3):601–615. doi: 10.1083/jcb.73.3.601. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Hyams J. S., Borisy G. G. Nucleation of microtubules in vitro by isolated spindle pole bodies of the yeast Saccharomyces cerevisiae. J Cell Biol. 1978 Aug;78(2):401–414. doi: 10.1083/jcb.78.2.401. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Inoué S., Ritter H., Jr Dynamics of mitotic spindle organization and function. Soc Gen Physiol Ser. 1975;30:3–30. [PubMed] [Google Scholar]
- Inoué S., Ritter H., Jr Mitosis in Barbulanympha. II. Dynamics of a two-stage anaphase, nuclear morphogenesis, and cytokinesis. J Cell Biol. 1978 Jun;77(3):655–684. doi: 10.1083/jcb.77.3.655. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Margolis R. L., Wilson L., Keifer B. I. Mitotic mechanism based on intrinsic microtubule behaviour. Nature. 1978 Mar 30;272(5652):450–452. doi: 10.1038/272450a0. [DOI] [PubMed] [Google Scholar]
- Mc2ntosh J. R., Cande Z., Snyder J., Vanderslice K. Studies on the mechanism of mitosis. Ann N Y Acad Sci. 1975 Jun 30;253:407–427. doi: 10.1111/j.1749-6632.1975.tb19217.x. [DOI] [PubMed] [Google Scholar]
- McGill M., Brinkley B. R. Human chromosomes and centrioles as nucleating sites for the in vitro assembly of microtubules from bovine brain tubulin. J Cell Biol. 1975 Oct;67(1):189–199. doi: 10.1083/jcb.67.1.189. [DOI] [PMC free article] [PubMed] [Google Scholar]
- McIntosh J. R., Cande W. Z., Snyder J. A. Structure and physiology of the mammalian mitotic spindle. Soc Gen Physiol Ser. 1975;30:31–76. [PubMed] [Google Scholar]
- Nicklas R. B., Brinkley B. R., Pepper D. A., Kubai D. F., Rickards G. K. Electron microscopy of spermatocytes previously studied in life: methods and some observations on micromanipulated chromosomes. J Cell Sci. 1979 Feb;35:87–104. doi: 10.1242/jcs.35.1.87. [DOI] [PubMed] [Google Scholar]
- Nicklas R. B. Mitosis. Adv Cell Biol. 1971;2:225–297. doi: 10.1007/978-1-4615-9588-5_5. [DOI] [PubMed] [Google Scholar]
- Oakley B. R., Heath I. B. The arrangement of microtubules in serially sectioned spindles of the alga Cryptomonas. J Cell Sci. 1978 Jun;31:53–70. doi: 10.1242/jcs.31.1.53. [DOI] [PubMed] [Google Scholar]
- Pickett-Heaps J. D., Tippit D. H. The diatom spindle in perspective. Cell. 1978 Jul;14(3):455–467. doi: 10.1016/0092-8674(78)90232-5. [DOI] [PubMed] [Google Scholar]
- Snyder J. A., McIntosh J. R. Initiation and growth of microtubules from mitotic centers in lysed mammalian cells. J Cell Biol. 1975 Dec;67(3):744–760. doi: 10.1083/jcb.67.3.744. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Subirana J. A. Role of spindle microtubules in mitosis. J Theor Biol. 1968 Jul;20(1):117–123. doi: 10.1016/0022-5193(68)90097-0. [DOI] [PubMed] [Google Scholar]
- Summers K., Kirschner M. W. Characteristics of the polar assembly and disassembly of microtubules observed in vitro by darkfield light microscopy. J Cell Biol. 1979 Oct;83(1):205–217. doi: 10.1083/jcb.83.1.205. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Telzer B. R., Moses M. J., Rosenbaum J. L. Assembly of microtubules onto kinetochores of isolated mitotic chromosomes of HeLa cells. Proc Natl Acad Sci U S A. 1975 Oct;72(10):4023–4027. doi: 10.1073/pnas.72.10.4023. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Weisenberg R. C., Rosenfeld A. C. In vitro polymerization of microtubules into asters and spindles in homogenates of surf clam eggs. J Cell Biol. 1975 Jan;64(1):146–158. doi: 10.1083/jcb.64.1.146. [DOI] [PMC free article] [PubMed] [Google Scholar]