Tatsuru Togo
University of California, Berkeley
Network
Latest external collaboration on country level. Dive into details by clicking on the dots.
Publication
Featured researches published by Tatsuru Togo.
The Biological Bulletin | 1995
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
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
Tatsuru Togo; Janet M. Alderton; Guo-Qiang Bi; Richard A. Steinhardt
Molecular Biology of the Cell | 2000
Tatsuru Togo; Tatiana B. Krasieva; Richard A. Steinhardt
Molecular Biology of the Cell | 2003
Tatsuru Togo; Janet M. Alderton; Richard A. Steinhardt
Zygote | 1999
Tatsuru Togo; Janet M. Alderton; Richard A. Steinhardt
Archive | 2014
Ikuko Yazaki; Toko Tsurugaya; Luigia Santella; Gabriele Amore; Shinichiro Kusunoki; Akiko Asada; Tatsuru Togo; Stazione Zoologica; A. Dohrn
Zoological Science | 2005
Toko Tsurugaya; Ikuko Yazaki; Tatsuru Togo; Hirosuke Fujisawa; Koji Akasaka
Zoological Science | 2004
Masaaki Morisawa; Kensuke Komatsu; Tatsuru Togo; Sachiko Morisawa; Kazuya Kikuchi; Tetsuo Nagano
Zoological Science | 2002
Tatsuru Togo; Masaaki Morisawa