@phdthesis{oai:tsukuba.repo.nii.ac.jp:00008433,
 author = {大場, 浩美 and Oba, Hiroyoshi},
 month = {},
 note = {Employment of mutants which have the defects in cell division makes it possible to elucidate the molecular mechanisms of cell division. I used cdaAl of a temperature-sensitive Tetrahymena mutant having a defect in the formation of fission zone where contractile ring is formed. I expected that the product of cdaA locus is a factor required for the formation of fission zone. In this study, I identified a protein showing a difference in electrophoretic mobility between wild-type and cdaAl cell as a possible gene product of cdaA locus. The product had a product of cdaA locus. The product had a molecular weight mass of 85,000, isoelectric point of 4.7, so that it was named p85. Expression of either wild-type p85 or cdaA p85   coincided with expression of respective phenotype in the descendants derived from the cross between cdaAl and wild-type cells, which strongly suggested that p85 is indeed a cdaA gene product. Furthermore, immunofluorescence staining demonstrated that specific localization of p85 occurred at equatorial basal bodies at the time just before the formation of fission zone which should be formed in front of the equatorial basal bodies. Such a localization must be prerequisite for cell division because the localization failed to occur in cdaAl cell at the restrictive temperature. It was found that contractile ring microfilaments ran along the basal bodies where p85 was localized. The fact suggested that p85 plays a important role in formations of both fission zone and contractile ring. Time and place of polymerization of contractile ring microfilaments were investigated in known-aged Tetrahymena cells by microinjecting skeletal muscle actin which might act as a functionally-incompatible analogue of Tetrahymena actin. The results suggested that the polymerization of contractile ring microfilaments occurred at cell equator in a 17-minutes-period before the onset of cell division. The polymerization of contractiloe ring microfilaments coincided with the fisson zone formation, and both events were only slightly preceded by the equatorial localization of p85. These facts lead a notion that p85 localization at equatorial basal bodies triggers both formation of fission zone and polymerization of contractile ring microfilaments, and that p85 provides the polymerizatiion nuclei for Tetrahymena action. It can be said that p85 identified as the gene product of cdaA locus is a crucial determinant factor for the time and place of division furrow constriction., 1991},
 school = {筑波大学, University of Tsukuba},
 title = {Studies on molecular mechanisms of division furrow formation in Tetrahymena},
 year = {1992}
}