A Deep Insight of Spermatogenesis and Hormone Levels of Aqua-Cultured Turbot (Scophthalmus maximus)

Abstract

Turbot (Scophthalmus maximus) is an important marine fish both in Europe and North China. Although there are plenty of studies on the reproduction of turbot, the complete cytological process of spermatogenesis remains unclear. In this study, we investigated the submicroscopic structure of total 23 types of male germ cells throughout the breeding season, with a relatively complete process of the primary spermatocytes. We found that the spermatid tail formed early at Spermatid II, and there were at least 16 spherical mitochondria in the spermatozoa. The hepatosomatic index (HSI) and gonadosomatic index (GSI) both peaked during the breeding season. Preliminary analysis showed that the vitality of mature sperm was negatively correlated with the proportion of sperm deformity. The serum 3,5,3′-triiodothyronine (T3), 5-hydroxytryptamine (5-HT), testosterone (T), 17α,20β-Dihydroxy-4-pregnen-3-one (17α,20β-DHP), and 17β-estradiol (E2) all increased during the maturity period, with the change of T content most noticeable. Whereas in the testis, an overall high level of 11-ketotestosterone (11-KT) was more remarkable. The expression and localization of androgen receptor (AR) mRNA showed that the AR was highly expressed at the stages of II (15 – 70 g), with a slight rebound at the mature stages [IV(2200 g) to V(2500 g)], whose change was ahead to the changes of T and 11-KT. Fluorescence in situ hybridization (FISH) analysis showed that the AR mainly distributed in but not limited to Sertoli cells. This study represents the most complete overview of the reproductive cycle and spermatogenesis of turbot, which provides an important reference for the reproduction research and the guidance of flatfish breeding.

Production of sterile mono-sex triploid yellow drum (Nibea albiflora): genotypic females and sex-reversed phenotypic males with emphasis on utilization as surrogate broodstock

“…However, only small amounts of SZ-like cells were produced in the lobules in triploid testes during the first spawning season. Compared with ultrastructural features of normal spermatogenesis in fish species (Yang et al 2021a , b ; Liu et al 2021 ; Papah et al 2013 ), triploid male yellow drum also had seven types of male germ cells including SPG, five types of SCs and SZ. However, a large number abnormal anaphase/telophase II SCs and ST varied in size and DSs were also observed in triploid testes.…”

Single-cell transcriptome unravels spermatogonial stem cells and dynamic heterogeneity of spermatogenesis in seasonal breeding teleost

“…In fish, testicular development is generally classified into six stages, from I to VI, based on the presence of main and typical spermatogenic cells (Chaves-Pozo et al, 2005; Siqueira-Silva et al, 2013; Schulz et al, 2010; Yan et al, 2022). Typically, the testis at stage I occurs only once in a fish’s lifetime, and is characterized by a large number of spermatogonia (Liu et al, 2021; Schulz et al, 2010; Yang et al, 2018). During spermatogenesis, these SPG undergo meiosis and gradually differentiate into millions of spermatozoa in the spawning season (Schulz et al, 2010; Wang et al, 2023).…”