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

Developmental Biology 分野


Research in progress: 1) Molecular and cellular mechanisms of tail shaping during ascidian embryogenesis; 2) Molecular mechanisms of germline segregation in ascidian embryos; 3) Role of calcium signaling during oocyte maturation and fertilization; 4) Characterization of egg activating substance (sperm factor) from spermatozoa; 5) Mechanisms of light-induced spawning and oocyte meiotic maturation in hydrozoan jellyfish; 6) Developmental and evolutionary analysis of embryogenesis based on the comparison between direct and indirect development in sea urchins; and 7) Structure and function of gene regulation networks.

Lab-fig1 Fig 1. A) An adult of the ascidian, Halocynthia roretzi. B) Germline cells in the ascidian tailbud stage embryo. Their membranes and nuclei are visualized in green and red, respectively. C) Epidermal cells (green) in the ascidian neurula just before the start of tail formation.
Fig 2. Spatial expression of PjFoxA, a foxA-class gene of the direct developing sand dollar Peronella japonica revealed by whole-mount in situ hybridization. Expression of FoxA mRNA (blue) is observed in the presumptive adult rudiment.
Fig 3. Calcium changes in ascidian (Ciona savignyi) oocytes after fertilization. Each number shows the time in seconds after addition of sperm. (pb: 1st polar body)


Our laboratory is one of the research units in the Asamushi Research Center for Marine Biology, located in the local town of Asamushi in the “Mutsu” bay area of northern Japan, which is known as one of the richest place for marine life in the Tohoku area. Benefitting from our location in such a place, we are utilizing a variety of the marine invertebrate species available in the sea around us and are interested in understanding molecular and cellular mechanisms and evolutionary aspects of early development of these animals, ranging from oocyte maturation through fertilization, to embryogenesis. We are working on several issues in the above research field using techniques such as micro-manipulation, molecular biology, and live imaging, and hope to discover more of the surprising and beautiful logic of developmental and evolutionary processes behind the marine lives, as we are just beginning to understand these little-studied animals.


Professor Gaku Kumano
  • Molecular and Cellular mechanisms of tail shaping during ascidian embryogenesis
  • Molecular mechanisms of germline segregation in primitive chordate embryos
Associate Professor Keiichiro Kyozuka
  • Mechanism of oocyte maturation and fertilization in marine invertebrates, focusing on Ca2+ function in the oocyte
Associate Professor Takuya Minokawa
  • Sea urchin developmental mechanism
  • Marine invertebrate evolutionary developmental biology
Assistant Professor Ayaki Nakamoto
  • Cell polarity and morphogenesis of ascidian embryos

Awards Granted to Graduate Students


Thesis Titles

Master Degree


Ph.D. Degree


A Student’s View


Isao Takahashi 


Undergraduate University and Department

Nagahama Institute of Bio-Science and Technology

Research Subject

Study of the Ca2+ increase in the oocyte during fertilization in the starfish, Asterina pectinifera.

Our laboratory is located at the seashore facing Mutsu Bay in Asamushi, Aomori-city. The institute is about 400 kilometers north of our main campus in Sendai. We study oocyte maturation, fertilization, and morphogenesis in early development utilizing gametes and embryos from marine invertebrates such as ascidians, echinoderms, mollusks, annelids, and jellyfish. Many researchers who work with marine invertebrates, not only from other Institutes in Japan but also from abroad, visit our Institute frequently and we have the opportunity to talk with them without reserve.