Effect of high temperatures on sex ratio and differential expression analysis (RNA-seq) of sex-determining genes in from different river basins in Benin.

The high temperature sex reversal process leading to functional phenotypic masculinization during development has been widely described in Nile tilapia () under laboratory or aquaculture conditions and in the wild. In this study, we selected five wild populations of from different river basins in Benin and produced twenty full-sib families of mixed-sex (XY and XX) by natural reproduction. Progenies were exposed to room temperature or high (36.

Correction: Temperature preference of Nile tilapia (Oreochromis niloticus) juveniles induces spontaneous sex reversal.

[This corrects the article DOI: 10.1371/journal.pone.

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

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.

Temperature Preference and Sex Differentiation in African Catfish, Clarias gariepinus.

The African catfish Clarias gariepinus has a genetic sex determination system in which high temperature induces masculinization. The thermosensitive period for sex differentiation is short and occurs very early (from 6 to 8 days posthatching [dph]). As young juveniles can encounter high masculinizing temperature (36.

The sensitive period for male-to-female sex reversal begins at the embryonic stage in the Nile tilapia and is associated with the sexual genotype.

In this study, we sought to determine the mechanism of early sex reversal in a teleost by applying 4 hr feminization treatments to XY (17α-ethynylestradiol 2000 μg L(-1) ) and YY (6500 μg L(-1) ) Nile tilapia embryos on the first day post-fertilization (dpf). We then searched for changes in the expression profiles of some sex-differentiating genes in the brain (cyp19a1b, foxl2, and amh) and in sex steroids (testosterone, 17β-estradiol, and 11-ketotestosterone) concentrations during embryogenesis and gonad differentiation. No sex reversal was observed in YY individuals, whereas sex-reversal rates in XY progeny ranged from 0-60%.

Brief exposure of embryos to steroids or aromatase inhibitor induces sex reversal in Nile tilapia (Oreochromis niloticus).

This study aimed to develop sex reversal procedures targeting the embryonic period as tools to study the early steps of sex differentiation in Nile tilapia with XX, XY, and YY sexual genotypes. XX eggs were exposed to masculinizing treatments with androgens (17α-methyltestosterone, 11-ketotestosterone) or aromatase inhibitor (Fadrozole), whereas XY and YY eggs were subjected to feminizing treatments with estrogen analog (17α-ethynylestradiol). All treatments consisted of a single or double 4-hr immersion applied between 1 and 36 hour post-fertilization (hpf).

Physiological and proteomic responses to single and repeated hypoxia in juvenile Eurasian perch under domestication--clues to physiological acclimation and humoral immune modulations.

We evaluated the physiological and humoral immune responses of Eurasian perch submitted to 4-h hypoxia in either single or repeated way. Two generations (F1 and F5) were tested to study the potential changes in these responses with domestication. In both generations, single and repeated hypoxia resulted in hyperglycemia and spleen somatic index reduction.

Cortisol is responsible for positive and negative effects in the ovarian maturation induced by the exposure to acute stressors in Nile tilapia, Oreochromis niloticus.

The aim of the present study was to evaluate the effect of acute stress and cortisol injection on oocyte final maturation process in female Nile tilapia (Oreochromis niloticus). Handling followed by a prophylactic treatment (0.3 mL L(-1) H(2)O(2), 5 g L(-1) NaCl solution during 30 min) and an environmental change (transfer from a 2 m(3) fibreglass square tank to 50 L aquaria) were used as acute stressors and compared to a single cortisol injection (0.

Comparative study of the reproductive characteristics of XY male and hormonally sex-reversed XX male Eurasian perch, Perca fluviatilis.

In order to compare the reproductive capacity of XY male versus XX male (neomales) Eurasian perch (Perca fluviatilis), we determined the sperm quality (sperm concentration and motility) and reproductive characteristics such as gonadosomatic index (GSI), fertilization rate and sex steroid levels (testosterone, T; 17beta-estradiol, E2 and 11-ketotestosterone, 11KT) during the reproductive season. Median GSI was not significantly different between XY males (7.9%) and XX males (7.