Mieko Oguro
University of Tokyo
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Featured researches published by Mieko Oguro.
Biochemical and Biophysical Research Communications | 1980
Mieko Oguro; Masaki Shioda; Hiroshi Nagano; Yoshitake Mano; Fumio Hanaoka; Masa-atsu Yamada
Abstract Aphidicolin (a specific inhibitor of DNA polymerase-α) inhibited DNA synthesis in isolated nuclei from sea urchin embryos but ddTTP (an inhibitor of DNA polymerases-β and -γ) did not, indicating that DNA polymerase-α was responsible for DNA synthesis in isolated nuclei. DNA synthesis in isolated nuclei was inhibited by aphidicolin noncompetitively with respect to each of dNTPs indicating that properties of in situ DNA polymerase activity in isolated nuclei are different from those of the purified DNA polymerase-α which was inhibited by aphidicolin competitively with respect to dCTP and noncompetitively with respect to the other 3 dNTPs. Similar results were obtained using HeLa cell nuclei.
Development Growth & Differentiation | 1979
Susumu Ikegami; Takahiko Taguchi; Mochihiko Ohashi; Mieko Oguro; Hiroshi Nagano; Yoshitake Mano
Aphidicolin at 2 μg/ml caused 90% inhibition of mitotic cell division of sea urchin embryos at the I‐cell stage. However, at 40 μg/ml it did not affect meiotic maturational divisions of starfish oocytes, which do not involve DNA replication. At 2 μg/ml it caused 90% inhibition of incorporation of tritiated thymidine into DNA of sea urchin embryos but did not affect protein or RNA synthesis even at a higher concentration. At 2 μg/ml it also caused 90% inhibition of the activity of DNA polymerase α, obtained from the nuclear fraction of sea urchin embryos, but did not affect the activity of DNA polymerase β or γ. These findings suggest that DNA polymerase α is responsible for replication of DNA in sea urchin embryos.
Journal of Biochemistry | 1983
Mieko Oguro; Hiroshi Nagano
We succeeded in reconstituting the endogenous nuclear DNA synthesis of the sea urchin. Endogenous DNA synthesis of isolated nuclei was reconstituted by mixing the salt-treated nuclei (chromatin exhibiting essentially no endogenous DNA synthesis) and the salt extract containing DNA polymerase-alpha. DNA synthesis in this reconstitution system showed a level of activity and a mode of inhibition by aphidicolin similar to those of the original isolated nuclei (noncompetitive with respect to dCTP). On the other hand, the inhibitory mode was competitive with respect to dCTP in DNA synthesis in the reconstituted system obtained from the chromatin and purified DNA polymerase-alpha, indicating that some other factor(s) in addition to DNA polymerase-alpha is necessary for the reconstitution with reference to the inhibitory mode of aphidicolin. We also studied the template activity of the chromatin. When chromatin was used as a template, inhibition by aphidicolin of DNA polymerase-alpha was noncompetitive and uncompetitive with respect to the template at high and low concentrations, respectively. Treatment of chromatin with 5 M urea gave urea-treated chromatin (nonhistone protein-deprived chromatin) and the extract (mainly nonhistone protein fraction). Inhibition by aphidicolin of DNA polymerase-alpha was uncompetitive with respect to the urea-treated chromatin. However, when chromatin reconstituted from the urea-treated chromatin and the extract was used as a template, the inhibitory mode by aphidicolin was similar to that with original chromatin, indicating that the nonhistone protein fraction contained factor(s) which modified the inhibitory mode of aphidicolin. Thus, the inhibitory mode of aphidicolin is a useful parameter for monitoring the resolution and reconstitution of endogenous DNA synthesis of isolated nuclei.
Nature | 1978
Susumu Ikegami; Takahiko Taguchi; Mochihiko Ohashi; Mieko Oguro; Hiroshi Nagano; Yoshitake Mano
FEBS Journal | 1979
Mieko Oguro; Chiyo Suzuki-Hori; Hiroshi Nagano; Yoshitake Mano; Susumu Ikegami
Journal of Cellular Physiology | 1979
Susumu Ikegami; Shonan Amemiya; Mieko Oguro; Hiroshi Nagano; Yoshitake Mano
Nucleic Acids Research | 1983
Tokuko Haraguchi; Mieko Oguro; Hiroshi Nagano; Akitami Ichihara; Sadao Sakamura
Nucleic Acids Research | 1984
Mieko Oguro; Tadashi Yamashita; Hiroyoshi Ariga; Hiroshi Nagano
Journal of Biochemistry | 1982
Mieko Oguro; Hiroshi Nagano
Journal of Biochemistry | 1982
Mieko Oguro; Hiroshi Nagano