BDR researchers coming from diverse research fields are working together to achieve higher goals.

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About Us

About Us

Exploring the scientific foundations of life through interdisciplinary approaches to address society’s problems.

Photo of Team Leader

Team Leader
Tomoya Kitajima Ph.D.

Laboratory for Chromosome Segregation

Location Kobe / Developmental Biology Buildings

E-mail tomoya.kitajima[at]riken.jp

Please replace [at] with @.

Recruiting graduate students

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.

Research Theme

  • Analysis of the mechanisms underlying meiotic chromosome segregation in mammalian oocytes
  • Study of the mechanisms underlying chromosome segregation during mitosis in fertilized eggs
  • Age-related errors in oocytes and fertilized eggs

Selected Publications

Ogonuki N, Kyogoku H, Hino T, et al.
Birth of mice from meiotically arrested spermatocytes following biparental meiosis in halved oocytes.
EMBO Reports 23(7), e54992 (2022) doi: 10.15252/embr.202254992

Mori M, Yao T, Mishina T, et al.
RanGTP and the actin cytoskeleton keep paternal and maternal chromosomes apart during fertilization.
The Journal of Cell Biology 220(10), e202012001 (2021) doi: 10.1083/jcb.202012001

Mishina T, Tabata N, Hayashi T, et al.
Single-oocyte transcriptome analysis reveals aging-associated effects influenced by life stage and calorie restriction.
Aging Cell 20(8), e13428 (2021) doi: 10.1111/acel.13428

Hamazaki N, Kyogoku H, Araki H, et al.
Reconstitution of the oocyte transcriptional network with transcription factors.
Nature 589, 264-269 (2021) doi: 10.1038/s41586-020-3027-9

Courtois A, Yoshida S, Takenouchi O, et al.
Stable kinetochore-microtubule attachments restrict MTOC position and spindle elongation in oocytes.
EMBO Reports 22(4), e51400 (2021) doi: 10.15252/embr.202051400

Yoshida S, Nishiyama S, Lister L, et al.
Prc1-rich kinetochores are required for error-free acentrosomal spindle bipolarization during meiosis I in mouse oocytes.
Nature Communications 11, 2652 (2020) doi: 10.1038/s41467-020-16488-y

Ding Y, Kaido M, Llano E, et al.
The post-anaphase SUMO pathway ensures the maintenance of centromeric cohesion through meiosis I-II transition in mammalian oocytes.
Current Biology 28(10), 1661-1669 (2018) doi: 10.1016/j.cub.2018.04.019

Kyogoku H, Kitajima TS.
Large cytoplasm is linked to the error-prone nature of oocytes.
Developmental Cell 41(3), 287-298 (2017) doi: 10.1016/j.devcel.2017.04.009

Sakakibara Y, Hashimoto S, Nakaoka Y, et al.
Bivalent separation into univalents precedes age-related meiosis I errors in oocytes.
Nature Communications 6, 7550 (2015) doi: 10.1038/ncomms8550

Kim J, Ishiguro K, Nambu A, et al.
Meikin is a conserved regulator of meiosis-I-specific kinetochore function.
Nature 517(7535), 466-471 (2015) doi: 10.1038/nature14097

Solc P, Kitajima TS, Yoshida S, et al.
Multiple requirements of PLK1 during mouse oocyte maturation.
PLOS ONE 10(2), e0116783 (2015) doi: 10.1371/journal.pone.0116783

Yoshida S, Kaito M, Kitajima TS.
Inherent instability of correct kinetochore-microtubule attachments during meiosis I in oocytes.
Developmental Cell 33(5), 589-602 (2015) doi: 10.1016/j.devcel.2015.04.020

Kitajima TS, Ohsugi M, Ellenberg J.
Complete kinetochore tracking reveals error-prone homologous chromosome biorientation in mammalian oocytes.
Cell 146(4), 568-581 (2011) doi: 10.1016/j.cell.2011.07.031


Tomoya Kitajima

Team Leader

Shuhei Yoshida

Senior Scientist

Eishi Aizawa

Research Scientist

Osamu Takenouchi

Special Postdoctoral Researcher

Tappei Mishina

Special Postdoctoral Researcher

Hinako Takase

Visiting Researcher

Hirohisa Kyogoku

Visiting Scientist

Kohei Asai

Junior Research Associate

Kaori Hamada

Technical Staff II

Yuanzhuo Zhou

Student Trainee

Haruki Morioka

Student Trainee

MeiAkiko Mukose

Student Trainee