Department of Developmental Biology and Neurosciences
Division of Developmental and Cell Biology

Developmental Biology 分野

Keiichiro Kyozuka
キャンパス 浅虫海洋生物学教育研究センター(青森市浅虫)
専攻分野 Developmental biology, Reproductive Biology
連絡先 017-752-3397

Oocytes and sperm are single cells that do not maintain their activity as a single cell for long. I am interested in how these cells prolong their lives by successful fertilization. Gametes from marine invertebrates have excellent characteristics for the study of oocyte maturation and fertilization. I plan to introduce the benefits of these organisms as experimental materials in my lectures and marine biology courses.

1978-1982 Research Assistant, Faculty of Science, Tohoku University
1982-2000 Assistant Professor, Faculty of Science/Graduate School of Science, Tohoku University
2000-2004 Assistant Professor, Graduate School of Science, Tohoku University
2005-present Associate Professor, Graduate School of Life Sciences, Tohoku University
1992,1993, and 1994 Part-time Faculty, Department of Physiology, School of Medicine, Wayne State University, Detroit,; Lecturer
1999, 2002 Teaching staff UNESCO-ICRO International Training Course

Intracellular calcium signaling in the fertilized eggs of Annelida.
Nakano T, Deguchi R, Kyozuka K.
Biochem Biophys Res Commun. 450:1188-1194 (2014)

Mitochondrial activation and nitric oxide (NO) release at fertilization in echinoderm eggs.
Mohri T., Kyozuka K.
Chapter in book 187-190, "Sexual Reproduction in Animals and Plants", Sawada H., Inoue N, Iwao M eds. Springer, Tokyo Heidelberg New York Dordrecht London (2014).

Guanine nucleotides in the meiotic maturation of starfish oocytes: regulation of the actin cytoskeleton and of Ca(2+) signaling.
Kyozuka K, Chun JT, Puppo A, Gragnaniello G, Garante E, Santella L.
PLoS One. 20: e6296 (2009)

Nitric oxide (NO) increase at fertilization in sea urchin eggs upregulates fertilization envelope hardening.
Mohri T, Sokabe M, Kyozuka K.
Dev Biol. 322: 251-262 (2008)

Actin cytoskeleton modulates calcium signaling during maturation of starfish oocytes.
Kyozuka K, Chun JT, Puppo A, Gragnaniello G, Garante E, Santella L.
Dev Biol. 320: 426-435 (2008)

Novel two-step Ca2+ increase and its mechanisms and functions at fertilization in oocytes of the annelidan worm Pseudopotamilla occelata.
Nakano T, Kyozuka K, Deguchi R.
Dev Growth Differ. 50: 365-379 (2008)

Two phases of calcium requirement during starfish meiotic maturation.
Tosuji H, Seki Y, Kyozuka K.
Comp Biochem Physiol A Mol Integr Physiol. 147:432-437 (2007)

Serotonin stimulates [Ca2+]i elevation in ciliary ectodermal cells of echinoplutei through a serotonin receptor cell network in the blastocoel.
Katow H, Yaguchi S, Kyozuka K.
J Exp Biol. 210: 403-412 (2007)


Japanese Society of Developmental Biologists
The Zoological Society of Japan


Marine Biology and PracticeII (Faculty of Science)
Advanced Lecture on Developmental Cell Biology, Advanced Cell Biology


Intracellular Ca2+ changes during fertilization in the ascidian, Ciona savignyi

We study the mechanism of oocyte maturation and fertilization, using ascidians, echinoderms, mollusks, annelids, and jellyfish as experimental models. Our research projects are categorized in three primary topics, which are: 1) how an oocyte obtains the ability for the re-initiation of meiosis and further development by the spermatozoon; 2) how the fertilizing spermatozoon enters the oocyte; and 3) how the fertilizing spermatozoon activates the oocyte.

During re-initiation of oocyte maturation by maturation inducing hormones and the activation of the oocyte at fertilization by the spermatozoon, the increase in intracellular Ca2+ plays an important role. In most cases, artificial induction of Ca2+ increase in the oocyte is sufficient to trigger the re-initiation of meiosis and egg action in many species. Therefore, we are going to clarify how Ca2+ is involved in those events.


Our laboratory is located far from the main campuses in Sendai, but Mutsu Bay around our Institute offers an abundance of nature and marine organisms. We can collect and work with a variety of interesting animals such as cnidarians (left), annelids, and mollusks (right) as shown in the pictures below, and more.

Lab members

Asuka Komatsu (M2)
Miyagi University of Education
Mechanism of spermatogenesis and spawning in jellyfish, Cladonema pacificum.

Isao Takahashi (D3)
Nagahama Institute of Bio-Science and Technology,
Study for the Ca2+ increase in the oocyte during fertilization in starfish, Asterina pectinifera.