公募研究

https://www.mext.go.jp/content/20260714_mxt_gakjokik-000043238_04.pdf (See the section for this research area, p. 26)

In organisms with sex, stably maintaining males and females is essential for species persistence. Sex determination by sex chromosomes is a common mechanism because it stabilizes sex ratios. However, due to their unique evolutionary properties, sex chromosomes tend to degenerate over time, creating a paradox: they sustain sex but also risk its eventual loss. To resolve this paradox, we propose the concept of a “sex chromosome cycle,” in which organisms maintain sex by repeatedly replacing sex chromosomes during evolution. This research aims to elucidate the mechanisms and biological significance of maintaining sex at each stage of this cycle through integrated approaches combining observation, theory, and experimental validation.

[Research area A03: Diverse sex chromosomes across organisms]
Planned Research focuses on organisms such as the Amami spiny rats, frogs, Drosophila, Silene latifolia, humans, mice, medaka, sticklebacks, and guppies, while also welcoming Publicly Offered Research on a broader range of species. Research on diverse systems (e.g., XY, ZW, and UV), plants at different stages of the cycle, and fungi or yeasts with mating types is encouraged; however, we also welcome other diverse studies on sex chromosomes. Projects elucidating evolutionary mechanisms or aiming at applications in agriculture, livestock, and fisheries are also within scope.

[Research area B04: Diverse functions of sex chromosomes and their genetic basis]
In sex chromosomes with suppressed recombination, the genes linked to sex-determining loci are known to have diverse functions beyond sex determination, while accumulated transposable elements may have deleterious effects. We aim to tackle these advantages and disadvantages of sex chromosomes in Planned Research, and we also invite proposals addressing these aspects of sex chromosomes, including those with medical applications. Studies on autosomes are also welcome if they address mechanisms shared with sex chromosomes, such as structural variation, recombination suppression, linkage disequilibrium, epigenomic regulation, dosage compensation, and transcriptional regulation.

[Research area C04: Theory and empirical validation of the sex chromosome cycle and diverse systems of sex determination]
We invite proposals that experimentally demonstrate the sex chromosome cycle (e.g., experimental evolution or semi-natural experiments), as well as theoretical studies. Proposals estimating turnover rates or exploring ecological factors that determine the turnover rates are also encouraged. This research area also seeks the possibility that other sex-determination systems (e.g., environmental sex determination, haplodiploidy, and parthenogenesis) function as backups of the cycle. Therefore, we also invite proposals targeting diverse sex-determination systems that do not rely on sex chromosomes. Studies predicting the evolution and population dynamics of sex-determination systems under fluctuating environments or developing new methodologies (e.g., chromosome engineering or genome structure manipulation) are also welcome.

All proposals are required to clearly describe their relevance to the concept of the sex chromosome cycle. Contributions to the advancement of this research area through collaborations within the program are highly desirable. Across all research areas, proposals utilizing genome informatics and AI-based approaches are welcome. Applications from early-career researchers are strongly encouraged. Applicants should apply either for Experimental Research (4.3 million JPY/year), or for Theoretical/Informatics Research or Exploratory Experimental Research (2.2 million JPY/year) under one of the above research areas.