Histological evaluation of sex differentiation and early sex identification in hatchery-produced greater amberjack (Seriola dumerili) reared in sea cages

Abstract

The histological process of gonadal differentiation, together with the endocrine changes of sex steroid hormones and some of their precursors was studied in hatchery-produced greater 32 amberjack (Seriola dumerili) from 101 until 408 days post-hatching (dph), with samplings conducted every 50 days. Histological processing showed that sex differentiation began at 34 101 dph with the formation of the ovarian cavity in females, while the presumptive males did not yet contain any germ cells in their gonad. At 150 dph we observed the first germ cells in 36 the developing testes. Sex differentiation in almost all sampled individuals was complete at 408 dph. No size dimorphism was observed between the sexes, and the sex ratio was 1:1, 38 suggesting that there was no influence of early rearing in captivity on sex differentiation.Plasma concentrations of adrenosterone (Ad), androstenedione (Δ4), 11-ketotestosterone 40 (11ΚΤ), testosterone (Τ), estradiol (Ε2), progesterone (P4) and 17,20β-dihydroxy-4-pregnen-3-one (17,20βP) were measured in males and females with the use of liquid chromatography 42 tandem mass spectrometry (LC-MS/MS) to examine their role in the sex differentiation process. From the seven hormones, the only one that exhibited differences between the sexes 44 was 11-KT and the plasma 11-KT concentration was found to be a useful indication of greater amberjack sex. Variations were observed in the mean values of Ad, Δ4, 11-KT, T, P4 46 and 17,20βP over time in one or both sexes, indicating their involvement in the sex differentiation process. 48

Sex-Inclined Piwi-Interacting RNAs in Serum Exosomes for Sex Determination in the Greater Amberjack (Seriola dumerili)

“…To accurately identify the sex of greater amberjack, the gonadal samples were used to make paraffin sections for hematoxylin-eosin staining [ 2 , 71 ]. The gonadal samples were firstly fixed by paraformaldehyde solution overnight, followed by gradient dehydration with ethanol.…”

“…The greater amberjack ( Seriola dumerili ) is economically valuable worldwide and mainly inhabits the deep sea environment, and is characterized by fast growth, good taste, and high nutritional value [ 1 , 2 , 3 , 4 ]. Owing to its high economic value, extensive studies have focused on the artificial domestication and breeding of greater amberjack since the 1990s [ 5 ].…”

“…For example, observations of the gonads (only at the stage of sexual maturity) and histological analyses cause fish damage or even death [ 18 ]. The estimation of the 11-ketotestosterone (11-KT) concentration and 11-KT/estradiol (E 2 ) ratio in the serum is not effective for young adults with very low blood hormone levels [ 2 ]. Sex-associated single nucleotide polymorphisms (SNPs) in greater amberjack are mainly found on chromosome 12 (approximately 7.1 Mbp) [ 1 , 19 ].…”

Assessing the Toxicity of Lagocephalus sceleratus Pufferfish from the Southeastern Aegean Sea and the Relationship of Tetrodotoxin with Gonadal Hormones

“…Besides TTX determination, the levels of steroid hormones were also measured in L. sceleratus specimens using the method of Papadaki et al [59] with some modifications. Due to the fact that fish blood sampling was not possible, the analysis of hormones had to be made on the available tissue samples.…”

“…Samples were evaporated to dryness (EZ-2 centrifugal evaporator, Genevac Ltd.; Ipswich, United Kingdom) at 35 • C for 2.5 h and reconstituted in 400 µL of 20% methanol. Subsequently, hormones separation was performed using the SPE method previously described for plasma samples by Papadaki et al [59]. In brief, microcartridges dry-packed with 10 mg of C18 sorbent (Strata-X 33 µm polymeric reversed phase; Phenomenex, Aschaffenburg Germany) were initially conditioned with 500 µL of methanol and 500 µL of water and, thereafter, the reconstituted samples were loaded.…”