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

Analysis of Sex Chromosome Evolution in the Clade Palaeognathae from Phased Genome Assembly.
Okuno M., Mizushima S., Kuroiwa A., Itoh T.
Genome Biol. Evol., 2021, 13, evab242.
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.
Sci. Rep., 2020, 20073. * Equally contribution.
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., 2019, 248, 784-794.
Over-expression of DMRT1 induces the male pathway in embryonic chicken gonads.
Lambeth L.S., Raymond C.S., Roeszler K.N., Kuroiwa A., Nakata T., Zarkower D. and Smith C.A.
Dev. Biol., 2014, 389, 160-172.
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., 2013, 110, 3417-3422.
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