Gametogenesis and vasa expression are seasonally regulated in yellow drum (Nibea albiflora)

Abstract

Seasonal reproduction is a strategy used by many marine fish to adapt to environmental changes. However, the composition of germ cells and environmental cues throughout the reproductive cycle in seasonal breeding fish is not well understood. This study investigated the gonadal development of Nibea albiflora at two ages during its annual reproductive cycle. We observed similar testicular development in 1-year-old and 2-year-old males, with two spermiation periods in spring and autumn. In contrast, 1-year-old females showed non-seasonal ovarian regression, while 2-year-old females had seasonally regulated development, with extended spawning from spring to autumn. Additionally, our correlation analysis between temperature and gonadal development revealed a close association of seasonal gametogenesis with water temperature. Notably, both testes and ovaries stagnated at the regression stage at the lowest winter temperature (10 ℃), resuming gametogenesis as temperatures increased in spring. Moreover, we analyzed and found that the expression levels of vasa, a specific marker for early germ cells, were seasonally regulated with peak levels in spring for the testis and in winter for the ovary. These findings enhance our understanding of germ cell activity under the seasonal reproductive cycle in teleosts, and provide a basis for the aquaculture and conservation management of N. albiflora.