Precocious maturation in male tiger pufferfish Takifugu rubripes: genetics and endocrinology

Abstract

Testes of the tiger pufferfish Takifugu rubripes are a delicacy in Japan, and selective breeding for a male precocious phenotype, i.e., with early initiation of testes development, is desirable. However, it is unknown if precocious gonad development in this species is under genetic control. Here, we investigated genetic involvement in precociousness by using progeny tests with sires from two cultured populations, including a family line anecdotally known for its precociousness, and a wild population. Progeny derived from the “precocious” line consistently had greater testes weight than that from the other lines, even after accounting for effects of body weight, which indicates that precociousness is truly heritable. We also compared chronological changes in plasma steroid hormones between progenies sired by males from the precocious line and a wild population, and found that the precocious family line had higher levels of plasma estradiol-17β (E2) prior to the initiation of testicular development. Our findings suggest that selective breeding for testes precociousness in the tiger pufferfish is feasible, and that plasma E2 may be an indicator of this phenotype, which would allow for phenotype evaluation without the need to sacrifice specimens.