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Featured researches published by Tatsuru Togo.


The Biological Bulletin | 1995

Existence of three mechanisms for blocking polyspermy in oocytes of the mussel Mytilus edulis

Tatsuru Togo; Kenzi Osanai; Masaaki Morisawa

We found the existence of a three-step mechanism to block polyspermy in the oocyte of the mussel Mytilus edulis. When the oocytes were inseminated within 30 min after spawning, they underwent monospermic fertilization over a wide range of sperm-oocyte ratios up to 5 x 103. A transient depolarization of the oocyte plasma membrane (fertilization potential) was observed immediately after insemination. Low-sodium seawater induced polyspermy and decreased the amplitude of the fertilization potential, suggesting the existence of a fast block to polyspermy that is dependent on depolarization of the plasma membrane. When the fertilized oocytes were inseminated again at a sperm-oocyte ratio that is great enough to give a high rate of polyspermy in initial insemination, many sperm could not undergo the acrosomal reaction and thus could not penetrate fertilized oocytes. The remaining sperm underwent an acrosomal reaction and the acrosomal process protruded through the vitelline coat, but it did not fuse with the oocyte plasma membrane. These findings suggest the existence of two strategies constituting a late polyspermy block: suppression of acrosomal reaction and block of contact or fusion between the plasma membranes of sperm and oocyte.


Journal of Experimental Zoology | 1999

Mechanisms for blocking polyspermy in oocytes of the oyster Crassostrea gigas

Tatsuru Togo; Masaaki Morisawa

We showed here the mechanisms to block polyspermy in the oocyte of the oyster Crassostrea gigas. When the fertilized monospermic oocytes were inseminated again with high sperm-oocyte ratio 15 min after the initial insemination, sperm could not penetrate into the oocytes; the oocytes were still monospermic. Insemination in low-sodium artificial seawater induced polyspermy, suggesting the occurrence of a fast polyspermy block caused by depolarization of the plasma membrane at fertilization. Requirement of external sodium ion for blocking polyspermy continued for 15 min after fertilization. Release of proteases from oocytes at fertilization was not observed. Electron microscopic observations showed that re-inseminated sperm could undergo acrosome reaction and bind to the fertilized oocytes, but acrosomal process did not fuse with the oocyte plasma membrane. These results suggest that blockage of contact or fusion of the plasma membrane between sperm and oocyte acts as a slow polyspermy block in Crassostrea. J. Exp. Zool. 283:307–314, 1999.


Journal of Cell Science | 1999

The mechanism of facilitated cell membrane resealing

Tatsuru Togo; Janet M. Alderton; Guo-Qiang Bi; Richard A. Steinhardt


Molecular Biology of the Cell | 2000

A Decrease in Membrane Tension Precedes Successful Cell-Membrane Repair

Tatsuru Togo; Tatiana B. Krasieva; Richard A. Steinhardt


Molecular Biology of the Cell | 2003

Long-Term Potentiation of Exocytosis and Cell Membrane Repair in Fibroblasts

Tatsuru Togo; Janet M. Alderton; Richard A. Steinhardt


Zygote | 1999

The mechanism of cell membrane repair.

Tatsuru Togo; Janet M. Alderton; Richard A. Steinhardt


Archive | 2014

localization, micromere induction signalling and the oral-aboral axis formation in early sea urchin embryos

Ikuko Yazaki; Toko Tsurugaya; Luigia Santella; Gabriele Amore; Shinichiro Kusunoki; Akiko Asada; Tatsuru Togo; Stazione Zoologica; A. Dohrn


Zoological Science | 2005

CA^ SIGNALING INVOLVED IN MICROMERE-SPECIFICATION IN THE SEA URCHIN DEVELOPMENT(Developmental Biology,Abstracts of papers presented at the 76^ Annual Meeting of the Zoological Society of Japan)

Toko Tsurugaya; Ikuko Yazaki; Tatsuru Togo; Hirosuke Fujisawa; Koji Akasaka


Zoological Science | 2004

ROLE OF ZINC ION ON THE INITIATION OF SPERM MOTILITY IN STARFISH(Cell Biology and Morphology,Abstracts of papers presented at the 75^ Annual Meeting of the Zoological Society of Japan)

Masaaki Morisawa; Kensuke Komatsu; Tatsuru Togo; Sachiko Morisawa; Kazuya Kikuchi; Tetsuo Nagano


Zoological Science | 2002

GPI-ANCHORED AMINOPEPTIDASE IS INVOLVED IN THE ACROSOME REACTION OF SPERM IN THE MUSSEL MYTILUS EDULIS(Developmental Biology)(Proceedings of the Seventy-Third Annual Meeting of the Zoological Society of Japan)

Tatsuru Togo; Masaaki Morisawa

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Guo-Qiang Bi

University of Science and Technology of China

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Ikuko Yazaki

Tokyo Metropolitan University

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Akiko Asada

Tokyo Metropolitan University

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