Masa-Aki Okubo

Publications (2)2.66 Total impact

• Article: Regional Differentiation of Cortical Structures and Their Reorganization during Cell Division in Paramecium trichium

  Tadao Takahashi, Masa‐Aki Okubo, Hiroshi Hosoya
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  ABSTRACT: We observed the cell surface of Paramecium trichium using three different methods. A non-dividing paramecium's cell surface consisted of three major regions outside of the oral apparatus: a) an oral groove region, with 2-cilia-2-basal-body (2C-2BB) units; b) a posterior region, occupying 1/4 to 1/5 of the cell surface, with 1-cilium-l-basal-body (1C-1BB) units; c) the remainder, with l-cilium-2-basal-body (1C-2BB) units. Five kinds of region-specific cortical reorganization occurred prior to cytokinesis: the 2C-2BB and 1C-1BB units were not duplicated, while the 1C-2BB units were reorganized to 2C-2BB, 1C-2BB or 1C-1BB units. These reorganizations of the cell surface progressed from the fission line to the anterior in the prospective anterior daughter cell, and to the posterior in the prospective posterior daughter cell, and bilaterally from the old and also newly developing oral apparatus in both daughter cells. In contrast, the development of cilia and their associated structures in each of the cortical units always progressed from posterior to anterior. The present work also showed that two fission lines began to develop bilaterally from the oral primordium, and then they joined to become a single fission line at the dorsal surface.
  Journal of Eukaryotic Microbiology 05/2007; 45(4):369 - 380. · 2.66 Impact Factor
• Article: Small Heat Shock Protein 27 (HSP27) Associates with Tubulin/Microtubules in HeLa Cells

  Mizuki Hino, Kazuki Kurogi, Masa-Aki Okubo, Maki Murata-Hori, Hiroshi Hosoya
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  ABSTRACT: One of the monoclonal antibodies raised against mitotic HeLa cells (termed as mH3) recognized a 27-kDa protein and stained microtubules in the mitotic spindles of HeLa cells. Immunoscreening of a HeLa cDNA library revealed that mH3 antigen is a small heat shock protein, HSP27. Immunoprecipitation analysis using mH3 suggested that both α- and β-tubulin are associated with HSP27. Further, sucrose-cushioned ultra centrifugation revealed that HSP27 is co-sedimented with taxol-stabilized microtubules. These results indicate that HSP27 associates with tubulin/microtubules in HeLa cells.
  Biochemical and Biophysical Research Communications.