Do sex reversal procedures differentially affect agonistic behaviors and sex steroid levels depending on the sexual genotype in Nile tilapia?

Abstract

In Nile tilapia Oreochromis niloticus, phenotypic males and females with different sexual genotypes (XX, XY, YY) have particular behavioral and physiological traits. Compared to natural XX females and XY males, XY and YY females and XX males expressed higher level of aggressiveness that could be related to higher levels of 17β-estradiol and 11-ketotestosterone, respectively. Our results suggest that the presence of a Y chromosome increases aggressiveness in females. However, since the same relationship between aggressiveness and the Y chromosome is not observed in males, we can hypothesize that the differences in aggressiveness are not directly dependent on the genotype but on the sex reversal procedures applied on young fry during their sexual differentiation to produce these breeders. These hormonal treatments could have permanently modified the development of the brain and consequently influenced the behavior of adults independently of their genotype. In both hypotheses (genotype or sex reversal influence), the causes of behavioral modifications have to be searched in an early modification of the brain sexual differentiation.

Identification and Comparison of microRNAs in the Gonad of the Yellowfin Seabream (Acanthopagrus Latus)

“…In addition, the putative target genes were significantly enriched in eight KEGG pathways, including “steroid biosynthesis”, “endocytosis”, and “phosphatidylinositol signaling system”. Sex steroids are tightly associated with sexual differentiation, gonadal development, and sexual reversal [ 58 , 59 , 60 ]. Endocytosis is required for the cellular uptake of sex steroids and yolk during oogenesis [ 61 , 62 ].…”

Gonadal Transcriptome Analysis of Sex-Related Genes in the Protandrous Yellowfin Seabream (Acanthopagrus latus)

“…The most DEG enriched sex-related KEGG pathways were associated with steroid production, including the steroid hormone biosynthesis (ko00140), steroid biosynthesis (ko00100), and ovarian steroidogenesis (ko04913) pathways ( Table 3). It is known that sex determination and maintenance are dependent steroid hormones (Senthilkumaran, 2015;Gennotte et al, 2017), the production of which is regulated by cytochrome P450 (cyp), steroid sulfatase, and hydroxysteroid dehydrogenases (hsd; Uno et al, 2012;Hilborn et al, 2017). The expression of seven cyp members (cyp7b, cyp21a, cyp11b1, cyp11a, cyp17a, cyp51, and cyp27b) and hsd17b2 were significantly downregulated during sex reversal, whereas the expression of cyp3a, cyp2j, cyp19a, hsd17b1, and hsd17b12 were significantly upregulated.…”

“…Sex reversal is tightly regulated by steroid hormones, such as estrogen and testosterone (Gennotte et al, 2017;Otani et al, 2017;Han et al, 2018). Steroid hormones are synthesized through a series of isomerization and hydroxylation reaction catalyzed by many enzymes, such as cyp, and hydroxysteroid dehydrogenases families (Hilborn et al, 2017).…”

Sex-ratio, early sex steroid profiles and cyp19a1b, dmrt1 and foxl2 gene expressions upon high temperature treatment of undifferentiated African catfish juveniles (Clarias gariepinus)

“…In teleosts, aromatase expression is high in the brain compared to mammals, resulting in high production of neuroestrogens (Blazquez and Somoza, 2010;Le Page et al, 2010). The brains aromatase cyp19a1b gene is specifically regulated there, suggesting early sexualization of the brain (Gennotte et al, 2017;Senthilkumaran et al, 2015). Its expression is more elevated in HT-induced male pejerrey (Diotel et al, 2010).…”