International Journal of Aquaculture, 2025, Vol.15, No.4, 184-196 http://www.aquapublisher.com/index.php/ija 184 Research Insight Open Access Molecular Basis and Regulatory Network of Sex Determination in Groupers Liting Wang, Manman Li Hainan Institute of Biotechnology, Haikou, 570206, Hainan, China Corresponding authors: manman.li@hitar.org International Journal of Aquaculture, 2025, Vol.15, No.4 doi: 10.5376/ija.2025.15.0018 Received: 01 Jun., 2025 Accepted: 15 Jul., 2025 Published: 02 Aug., 2025 Copyright © 2025 Wang and Li, This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Preferred citation for this article: Wang L.T., and Li M.M., 2025, Molecular basis and regulatory network of sex determination in groupers, International Journal of Aquaculture, 15(4): 184-196 (doi: 10.5376/ija.2025.15.0018) Abstract Grouper is a category of important value among marine economic fish. Due to its unique reproductive characteristics of hermaphrodite and female premature reproductive characteristics, gender can undergo two-way conversion in its life cycle. This phenomenon makes grouper an ideal model for studying the mechanisms of gender determination and differentiation of fish, but also poses challenges to aquaculture breeding. This study reviews the molecular basis and overall regulatory network of grouper gender determination mechanism, including sexual conversion in gender type and life cycle, reproductive gonadal histological characteristics, endocrine regulation of gender differentiation, identification and expression patterns of key gender-related genes, the role of non-coding RNA and epigenetics in gender regulation, the mechanism of action of sex hormones and their signaling pathways, the impact of external environmental factors on gender determination, and the method of constructing a gender regulatory network model in combination with multiomics data. We focused on the functions and interactions of genes that play a key role in the transition process of male and female (such as dmrt1 in male pathway and Foxl2 in female maintenance, etc.), and explained the role of epigenetic regulators such as miRNA and long-chain non-coding RNA in gender plasticity, as well as the role of pituitary-godal axis hormone signal in inducing gender reversal. Research on grouper gender determination not only helps to deeply understand the plasticity mechanism of gender differentiation in vertebrates, but also provides theoretical basis and practical guidance for controlling gender through molecular means in aquaculture and improving production efficiency. Keywords Grouper; Gender differentiation; Non-coding RNA; Epigenetics; Sex hormones 1 Introduction Grouper (Epinephelus) is a warm-water reef fish widely distributed in tropical and subtropical waters of the Indian Ocean and the Pacific Ocean. It is an important marine aquaculture economic fish in China and Southeast Asia. Grouper has delicious meat, high nutritional value, strong market demand, and has huge economic value and development prospects. At the same time, there are many types of grouper, and different species have their own characteristics in body color patterns and growth rates. They are important resources for the marine fishery and ornamental aquarium industries (Qu et al., 2021). Most grouper belong to the hermaphrodite female premature type, that is, the individual first develops and matures into functional females during puberty, and then a gender reversal of transition from female to male can occur later in the life cycle (Shi et al., 2010). In natural groups, juvenile and subadult individuals are mostly females, and only a few individuals can develop into males, and are often induced by the dominant females in the population to become males by social factors when they lose their original males. Grouper gender conversion is usually irreversible and does not redirect back to females once an individual turns from female to male (Evliyaoğlu et al., 2019). However, under artificial induction conditions, there have also been studies that have reported cases of male individuals re-expressing female traits after special treatment. Grouper's unique two-way gender conversion mechanism provides valuable materials for scientific research, but also complicates its breeding and breeding management: the proportion of male individuals in breeding groups is low and the structure of the breeding group is unstable, which brings difficulties to artificial breeding and strain improvement. Among vertebrates, the gender determination and differentiation mechanisms of fish are the most diverse and plastic. Unlike higher vertebrates, fish are often significantly affected by environmental factors such as
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