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2026


30 October, 2026

Identification of OMC1, a Factor Required for Long-Term Maintenance of Chromosome Cohesion in Oocytes

In mammalian oocytes, chromosome cohesion weakens with age, leading to chromosome segregation errors and aneuploidy. However, how the longevity of chromosome cohesion is determined has remained unclear. In collaboration with the Ishiguro laboratory at Chiba University and Kumamoto University, we identified OMC1, a novel factor required for the long-term maintenance of cohesin, the protein complex responsible for chromosome cohesion. OMC1 colocalizes with cohesin on chromosomes, and oocytes from OMC1-deficient mice prematurely lose cohesin and exhibit premature chromosome separation, resembling that observed in aged mice. The Omc1 gene is homologous to the human premature menopause-associated gene CCDC201. These findings are expected to advance our understanding of age-related infertility and may contribute to future developments in assisted reproductive technologies.
Iisaka S, Yoshida S, Shimada R, Mishina T, Fujiyama S, Koshiguchi M, Kimura R, Oki S, Araki K, Kitajima TS, Ishiguro K, "Oocyte-specific OMC1 is required for maintaining chromosome cohesion through reproductive life", Nature Aging, doi:10.1038/s43587-026-01245-5.
・Nature Aging
・Chiba University News "Understanding How Eggs Keep Their Chromosomes Intact Over Decades"


30 October, 2026

"Dynamic Reproductive Lifespan" Next Generation Scientist Meeting

Tomoya Kitajima, Shuhei Yoshida, So Shimamoto, Manami Koshiguchi, and Tao Pan attended the Next Generation Scientist Meeting of Grant-in-Aid for Transformative Research Areas（A) "Dynamic Reproductive Lifespan" held in Nagareyama from October 21 to 23, 2026 and presented their researches.


20 October, 2026

EMBO Workshop on the Cell Cycle

At EMBO Workshop on the Cell Cycle: Exploring Conservation and Divergence in Life’s Engine, held in Lisbon, Portugal from October 5 to 7, 2026, Tomoya Kitajima delivered an invited lecture.


20 October, 2026

FASEB SRC Consequences of Aneuploidy

At FASEB SRC Consequences of Aneuploidy, held in Melbourne, USA from September 28 to October 1, 2026, Tomoya Kitajima delivered an invited lecture.


20 October, 2026

NIH-NHLBI CDBC Seminar

At the NIH-NHLBI CDBC Seminar, held in Bethesda, USA, on September 23, 2026, Tomoya Kitajima delivered an invited lecture.

CDBC Seminar
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1 October, 2026

The 119th SRD Meeting

Remi Kanemura and Emiko Ichihara attended the 119th SRD Meeting held in Morioka from September 24 to 26, 2026 and presented their researches.


11 September, 2026

RIKEN Summer School

MeiAkiko Mukose and Tae Akizuki attended RIKEN Summer School 2026 held in Wako from September 10 to 11, 2026 and presented their researches. Tae won the poster award. Congratulations!


11 September, 2026

NIBS

At the 3rd Mini-Symposium on Early Embryology hosted by National Institute of Biological Sciences（NIBS), held in Beijing, China, on September 8, 2026, Tomoya Kitajima delivered an invited lecture.


4 September, 2026

S-HIGO Cutting-Edge Seminar

At the S-HIGO Cutting-Edge Seminar at Kumamoto University, held in Kumamoto on September 2, 2026, Tomoya Kitajima delivered an invited lecture.


8 July, 2026

Paper Celebration

We held a lab party to celebrate the publication of papers by Eishi Aizawa, So Shimamoto, and Hirohisa Kyogoku.

Paper Celebration
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12 June, 2026

The 59th Annual Meeting of the Japanese Society of Developmental Biologists

At the 59th Annual Meeting of the Japanese Society of Developmental Biologists, held in Hiroshima, from June 9 to 12, 2026, Tomoya Kitajima delivered an invited lecture.


9 June, 2026

International Symposium on Chromosome Dynamics

Miho Sakuma attended International Symposium on Chromosome Dynamics：from Structure to Cellular Function, held in Awaji Island, from 31 May to 3 June, 2026 and gave a poster presentation.


15 May, 2026

MAYosis2026

At MAYosis2026 2026, held online on May 12, 2026, Tomoya Kitajima delivered an invited lecture.


30 April, 2026

Cytoplasmic competition between pronuclei supports early embryonic development

In mammalian zygotes, maternal and paternal genomes are enclosed in separate pronuclei. Here, we show that these pronuclei compete for limited cytoplasmic factors, which constrains nuclear size and maintains proper epigenetic states. When both genomes are combined into a single pronucleus, this competition is lost, leading to nuclear enlargement, epigenetic dysregulation, and reduced developmental potential. These findings demonstrate that pronuclear separation is a fundamental mechanism supporting early embryonic development.

Kyogoku H, Tarama M, Matsuwaka M, Mishina T, Harada A, Nakagawa R, Kumon M, Shimizu Y, Ohkawa Y, Shibata T, Inoue A, Kitajima TS, "Cytoplasmic competition between separate parental pronuclei in zygotes", Nature, doi:10.1038/s41586-026-10417-7.
・Pubmed
・Nature
・Research Briefings in Nature
・News in Science


22 April, 2026

Live imaging of mammalian oocyte formation

In mammals, oocyte formation occurs within the fetus, and thus its process have remained largely elusive. In this study, we have established a technique for ex vivo culture of mouse fetal gonads combined with optical live imaging. Using this technique, we discovered stage-specific membrane blebbing of germ cells. Moreover, we observed no detectable intercellular transfer of organelles, unlike non-mammalian species, suggesting the existence of a mammal-specific mechanism underlying oocyte formation.

Aizawa E, Shimamoto S, Kajikawa E, Hara J, Abe T, Shibuya H, Kitajima TS, "Dynamic blebbing and absence of organelle transfer during mouse oocyte formation", The EMBO Journal, doi:10.1038/s44318-026-00780-6.
・Pubmed
・The EMBO Journal


21 April, 2026

Mitotic Spindle: From living and synthetic systems to theory

At Mitotic Spindle: From living and synthetic systems to theory, held in Dubrovnik, Croatia, from April 12 to 15, 2026, Tomoya Kitajima delivered an invited lecture.


10 April, 2026

Welcome party

We held a welcome party to celebrate Tao Pan, Tae Akizuki, and Mizuki Morihashi joining our lab.

Welcome Party
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2 April, 2026

New members joined

Tao Pan (Postdoctoral Researcher), and Tae Akizuki and Mizuki Morihashi (Trainees; Doctoral Students in the Graduate School of Biostudies at Kyoto University), joined our team in April.


30 March, 2026

RIKEN BAIHO Award

Our team has been awarded the RIKEN BAIHO Award, which is presented to researchers who have made outstanding contributions to research and development support. Congratulations!!

Tomoya Kitajima, Yuanzhuo Zhou, Kohei Asaki, and Hirohisa Kyogoku “Development of technologies to prevent age-associated egg aneuploidy”

RIKEN BAIHO Award
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24 March, 2026

PhD degree conferred

Yuanzhuo Zhou was awarded a PhD in Life Sciences at the Kyoto University Graduate School Degree Conferral Ceremony. Congratulations!!
・Kyoto University News

Doctoral Degree
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24 March, 2026

Welcome and farewell party

We held a welcome/farewell party and a bowling event to celebrate Hou joining us, Asai and Zhou starting their new jobs, and Wei entering graduate school.

Welcome and farewell party
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6 February, 2026

MASSIV 1.0

At MASSIV 1.0, held in Vancouver, Canada, from 19 to 22 January, 2026, Tomoya Kitajima delivered an invited lecture, and Kohei Asai presented a poster.


3 February, 2026

A new member joined

Shengqun Hou (Research Associate) joined our lab in February.


23 January, 2026

"Dynamic Reproductive Lifespan" Next Generation Scientist Meeting

Tomoya Kitajima, So Shimamoto, Manami Koshiguchi, Mihoko Fushii, and Remi Kanemu attended the Next Generation Scientist Meeting of Grant-in-Aid for Transformative Research Areas（A) "Dynamic Reproductive Lifespan" held in Kumamoto on 13 January, 2026 and presented their researches. So and Remi won the Best Poster Awards.

NGS Meeting
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23 January, 2026

SOKENDAI Life Science Retreat 2025

Tomoya Kitajima was invited to present our research at SOKENDAI Life Science Retreat 2025 held in Minamitsuru from 8 to 9 January, 2026.

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