Researcher Information



Biology for sex determination

Department of Biological Sciences, Reproductive and Developmental Biology


Molecular mechanism of sex determination in mammals and birds

FieldReproductive development, Genetics, Genome evolution
Keywordsex determination, gene, sex chromosome, Y chromosome, X chromosome, gonad, mammal, bird, spiny rat, chicken, Japanese quail, emu

Introduction of Research

My goal is to reveal molecular mechanism of sex determination in mammals and birds. In mammals, females have XX and males have XY sex chromosomes. The SRY gene determines male (testis) differentiation of embryo. SRY is a sex-determining gene located on the Y chromosome in placenta mammals. However, the Amami spiny rat (Tokudaia osimensis) which is a native wild rodent in Japan has no Y chromosome and SRY. I have studied two main topics in the spiny rat: why and how disappeared the Y chromosome, a new sex-determining mechanism independent of SRY.
On the other hand, birds have female heterogametic sex chromosomes (female: ZW, male: ZZ). It remains unknown mechanism of sex-determining in birds. The DMRT1 gene located on the Z chromosome is known as a testis determiner. However, the W-linked gene involved in female (ovary) determination has not found yet. I have tried to identify a novel W-linked gene using chicken, Japanese quail, and emu.

Juvenile of the Okinawa spiny rat. This species has been protected as a natural monument in Japan.
The section of gonads. The structure constructed by cells can be observed.
The Japanese quail used as an animal model of birds.

Representative Achievements

The neo-X does not form a Barr body but shows a slightly condensed structure in the Okinawa spiny rat (Tokudaia muenninki).
Kudo R, Yoshida I, Ceron LM, Mizushima S, Kuroki Y, Jogahara T, Kuroiwa A.
Cytogenet Genome Res. 162(11-12):632-643, 2023.
Turnover of mammal sex chromosomes in the Sry-deficient Amami spiny rat is due to male-specific upregulation of Sox9.
Terao M+, Ogawa Y+, Takada S, Kajitani R, Okuno M, Mochimaru Y, Matsuoka K, Itoh T, Toyoda A, Kono T, Jogahara T, Mizushima S, Kuroiwa A (+equally contribution)
Proc Natl Acad Sci U S A.119(49):e2211574119, 2022.
DOI: 10.1073/pnas.2211574119
Expression profiling of sexually dimorphic genes in the Japanese quail, Coturnix japonica.
Okuno M+, Miyamoto M+, Itoh T, Seki M, Suzuki Y, Mizushima S, Kuroiwa A (+equally contribution)
Sci Rep. 10:20073, 2020.
Spiny rat SRY lacks a long Q-rich domain and is not stable in transgenic mice.
Ogata Y, Nishikata M, Kitada K, Mizushima S, Jogahara T, Kuroiwa A
Dev Dyn. 248:784-794, 2019.
Chicken hemogen homolog is involved in the chicken-specific sex-determining mechanism.
Nakata T, Ishiguro M, Aduma N, Izumi H, Kuroiwa A
Proc Natl Acad Sci U S A., 110:3417-3422. 2013.
DOI: 10.1073/pnas.1218714110
Academic degreePh.D.
Academic background2001 Researcher of Japan Society for the Promotion Science
2003 Lcturer, Hokkaido University
2009 Associate Professor, Hokkaido University
2016 Professor, Hokkaido University
Affiliated academic societyThe Molecular Biology Society of Japan, The Society of Chromosome Research, The Genetic Society of Japan, The Society of Evolutionary Studies, Japan
Room addressFaculty of Science, Building 5 5-1105

1. Reproductive and Developmental Strategies; the Continuity of Life (eds: Kobayashi K, Kitano T, Iwao Y, Kondo M), Springer Japan
2. Avian Reproduction: From Behavior to Molecules (ed: Sasanami T), Springer Japan