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RIKEN Center for Biosystems Dynamics Research Laboratory for Chromosome Segregation

Team Leader: Tomoya Kitajima (Ph.D.)

Research Summary

Tomoya  Kitajima(Ph.D.)

The oocyte becomes an egg through meiosis. The egg fertilizes with a sperm and undergoes repeated cell divisions to give rise to an entire body. We study chromosome segregation during meiosis in oocytes and during mitosis in fertilized eggs, taking advantage of techniques for high-throughput and high-resolution live imaging of mouse oocytes combined with micromanipulation and genetic engineering methods. The first cell division that oocytes undergo is meiosis I. Chromosome segregation in this division is error-prone and the rate of errors increases with maternal age. Subsequently, chromosomes are segregated in meiosis II upon fertilization, and then segregated again in mitosis after DNA replication. We will reveal distinct mechanisms for chromosome segregation during these subsequent but fundamentally different cell divisions. By uncovering the mechanism of chromosome segregation during meiosis I in oocytes, we understand why oocyte meiosis I is error-prone and related to age. Comparing the mechanisms in meiosis I with those found in meiosis II and mitosis may provide insights into the capacity of cells to flexibly use different strategies for chromosome segregation. The findings will be exploited to collaborative studies with reproductive medicine.

Main Research Fields

  • Biology

Related Research Fields

  • Biological Sciences


  • Chromosome
  • Meiosis
  • Oocyte
  • Egg, ova

Selected Publications

Papers with an asterisk(*) are based on research conducted outside of RIKEN.

  • 1.Kyogoku, H. and Kitajima, T.S.:
    "Large cytoplasm is linked to the error-prone nature of oocytes."
    Developmental Cell 41(3), 287-298 (2017)
  • 2.Sakakibara Y, et al.:
    "Bivalent separation into univalents precedes age-related meiosis I errors in oocytes."
    Nature Communications 6:7550 (2015)
  • 3.Yoshida S, et al.:
    "Inherent instability of correct kinetochore-microtubule attachments during meiosis I in oocytes."
    Developmental Cell 33(5), 589–602 (2015)
  • 4.Kim J, et al.:
    "Meikin is a conserved regulator of meiosis-I-specific kinetochore function."
    Nature 517(7535):466-471 (2015)
  • 5.Solc P, et al.:
    "Multiple requirements of PLK1 during mouse oocyte maturation."
    PLOS ONE 10(2): e0116783 (2015)
  • 6.Kyogoku H, et al.:
    "Nucleolus Precursor Body (NPB): A Distinct Structure in Mammalian Oocytes and Zygotes."
    Nucleus 5(6):493-498 (2014)
  • 7.*Kitajima TS, et al.:
    "Complete kinetochore tracking reveals error-prone homologous chromosome biorientation in mammalian oocytes."
    Cell 146, 568-81 (2011)

Recent Research Results

Related Links

Lab Members

Principal investigator

Tomoya Kitajima
Team Leader

Core members

Shuhei Yoshida
Research Scientist
Aurelien Courtois
Research Scientist
Masashi Mori
Research Scientist
Hirohisa Kyogoku
Special Postdoctoral Researcher
Yi Ding
Research Associate
Kaori Hamada
Technical Staff II


Position Deadline
Seeking a Research Scientist (CS1901) Open until filled

Contact Information

4F, RIKEN BDR Developmental Biology Bldg.C,
2-2-3 Minatojima-minamimachi, Chuo-ku
Kobe, Hyogo
650-0047 Japan
Email: tkitajima [at] cdb.riken.jp