Institute for East China Sea Research, Organization for Marine Science and Technology, Nagasaki University, 1551-7 Taira-machi, Nagasaki, 851-2213, Japan.
Sesoko Station, Tropical Biosphere Research Center, University of the Ryukyus, 3422 Sesoko, Motobu, Okinawa, 905-0227, Japan.
Sci Rep. 2021 May 27;11(1):11117. doi: 10.1038/s41598-021-90691-9.
Vertebrates usually exhibit gonochorism, whereby their sex is fixed throughout their lifetime. However, approximately 500 species (~ 2%) of extant teleost fishes change sex during their lifetime. Although phylogenetic and evolutionary ecological studies have recently revealed that the extant sequential hermaphroditism in teleost fish is derived from gonochorism, the evolution of this transsexual ability remains unclear. We revealed in a previous study that the tunica of the ovaries of several protogynous hermaphrodite groupers contain functional androgen-producing cells, which were previously unknown structures in the ovaries of gonochoristic fishes. Additionally, we demonstrated that these androgen-producing cells play critical roles in initiating female-to-male sex change in several grouper species. In the present study, we widened the investigation to include 7 genera and 18 species of groupers and revealed that representatives from most major clades of extant groupers commonly contain these androgen-producing cells, termed testicular-inducing steroidogenic (TIS) cells. Our findings suggest that groupers acquired TIS cells in the tunica of the gonads for successful sex change during their evolution. Thus, TIS cells trigger the evolution of sex change in groupers.
脊椎动物通常表现为雌雄同体，其性别在整个生命周期中是固定的。然而，大约有 500 种（~2%）现存的硬骨鱼类会在其一生中改变性别。尽管系统发育和进化生态学的研究最近揭示了现存的硬骨鱼类顺序雌雄同体是从雌雄异体进化而来的，但这种变性能力的进化仍然不清楚。我们在之前的一项研究中表明，几个雌先雄体雌雄同体石斑鱼的卵巢被膜中含有功能性的雄激素产生细胞，这是以前在雌雄异体鱼类的卵巢中未知的结构。此外，我们证明这些雄激素产生细胞在几个石斑鱼物种的雌性到雄性的性别转变中发挥了关键作用。在本研究中，我们将调查范围扩大到包括 7 个属和 18 种石斑鱼，并发现大多数现存石斑鱼主要分支的代表都含有这些雄激素产生细胞，称为睾丸诱导类固醇生成（TIS）细胞。我们的研究结果表明，石斑鱼在其进化过程中为了成功的性别转变而在性腺的被膜中获得了 TIS 细胞。因此，TIS 细胞触发了石斑鱼性别转变的进化。
