Abstract
Purified tubulin solutions stabilized and augmented the birefringence (BR) of isolated Chaetopterus spindles. Tubulin was extracted from pig brain tissue in cold PEG buffer (0.1 M piperazine-N-N'-bis[2-ethane sulfonic acid], 1 mM ethylene bis-[oxyethylenenitrilo]tetraacetate, [EGTA], 2.5 mM guanosine triphosphate, [GTP], pH 6.94, at 25°C), and purified by two cycles of a reversible, temperature-dependent assembly-disassembly procedure. The spindle BR of the meiotic metaphase-arrested oocytes of Chaetopterus decreased linearly at a rate of 1.5 nm/min when perfused with PEG buffer without tubulin. In this hypotonic, calcium-chelating solution, the cell lysed within 1.5 min, and after a brief, transient rise, the BR disappeared in ca. 4 min from the time of buffer application. Cells perfused with tubulin in PEG buffer also showed BR decay at the same rate until cell lysis. Immediately upon cell lysis the spindle BR increased, initially at ca. 2.3 nm/min and then more slowly until the BR attained or exceeded intact cell values. Spindle and asters grew considerably larger than those in intact cells. From the kinetics of the transient BR increase after lysis, we infer that, initially, Chaetopterus cytoplasmic tubulin contributes to increased BR; further augmentation required added pig brain tubulin and most probably reflects the addition and incorporation of heterologous porcine tubulin into the spindle and asters. Isolated, augmented spindles depolymerized rapidly at 6°C. Upon return to 23°C, spindle BR returned slowly in tubulin-PEG. The BR of the isolates also decayed in solutions containing calcium ions 2.5 mM in excess of the EGTA. However, the isolates did not respond, or responded very slowly, to 1 mM colchicine or Colcemid and to dilution of tubulin with PEG solution. Microinjection into Chaetopterus oocytes of tubulin-PEG, but not PEG alone, enhanced spindle and aster BR which reversibly disappeared upon chilling the cell.
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Selected References
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- Borisy G. G., Olmsted J. B., Marcum J. M., Allen C. Microtubule assembly in vitro. Fed Proc. 1974 Feb;33(2):167–174. [PubMed] [Google Scholar]
- Borisy G. G., Olmsted J. B. Nucleated assembly of microtubules in porcine brain extracts. Science. 1972 Sep 29;177(4055):1196–1197. doi: 10.1126/science.177.4055.1196. [DOI] [PubMed] [Google Scholar]
- Inoué S., Sato H. Cell motility by labile association of molecules. The nature of mitotic spindle fibers and their role in chromosome movement. J Gen Physiol. 1967 Jul;50(6 Suppl):259–292. [PMC free article] [PubMed] [Google Scholar]
- LOWRY O. H., ROSEBROUGH N. J., FARR A. L., RANDALL R. J. Protein measurement with the Folin phenol reagent. J Biol Chem. 1951 Nov;193(1):265–275. [PubMed] [Google Scholar]
- MAZIA D., MITCHISON J. M., MEDINA H., HARRIS P. The direct isolation of the mitotic apparatus. J Biophys Biochem Cytol. 1961 Aug;10:467–474. doi: 10.1083/jcb.10.4.467. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Mazia D., Dan K. The Isolation and Biochemical Characterization of the Mitotic Apparatus of Dividing Cells. Proc Natl Acad Sci U S A. 1952 Sep;38(9):826–838. doi: 10.1073/pnas.38.9.826. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Olmsted J. B., Borisy G. G. Characterization of microtubule assembly in porcine brain extracts by viscometry. Biochemistry. 1973 Oct 9;12(21):4282–4289. doi: 10.1021/bi00745a037. [DOI] [PubMed] [Google Scholar]
- Olmsted J. B., Borisy G. G. Microtubules. Annu Rev Biochem. 1973;42:507–540. doi: 10.1146/annurev.bi.42.070173.002451. [DOI] [PubMed] [Google Scholar]
- Rebhun L. I., Sander G. Ultrastructure and birefringence of the isolated mitotic apparatus of marine eggs. J Cell Biol. 1967 Sep;34(3):859–883. doi: 10.1083/jcb.34.3.859. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Shelanski M. L., Gaskin F., Cantor C. R. Microtubule assembly in the absence of added nucleotides. Proc Natl Acad Sci U S A. 1973 Mar;70(3):765–768. doi: 10.1073/pnas.70.3.765. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Sisken J. E., Wilkes E., Donnelly G. M., Kakefuda T. The isolation of the mitotic apparatus from mammalian cells in culture. J Cell Biol. 1967 Jan;32(1):212–216. doi: 10.1083/jcb.32.1.212. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Weisenberg R. C. Microtubule formation in vitro in solutions containing low calcium concentrations. Science. 1972 Sep 22;177(4054):1104–1105. doi: 10.1126/science.177.4054.1104. [DOI] [PubMed] [Google Scholar]