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See detailDo sex reversal procedures differentially affect agonistic behaviours and sex steroid levels depending on the sexual genotype in Nile tilapia?
Gennotte, Vincent ULg; Akonkwa, Balagizi; Mélard, Charles ULg et al

in Journal of Experimental Zoology. Part A, Ecological Genetics and Physiology (in press)

In Nile tilapia Oreochromis niloticus, phenotypic males and females with different sexual genotypes (XX, XY, YY) have particular behavioural and physiological traits. Compared to natural XX females and XY ... [more ▼]

In Nile tilapia Oreochromis niloticus, phenotypic males and females with different sexual genotypes (XX, XY, YY) have particular behavioural 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-oestradiol 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 behaviour of adults independently of their genotype. In both hypotheses (genotype or sex reversal influence), the causes of behavioural modifications have to be searched in an early modification of the brain sexual differentiation. [less ▲]

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See detailTemperature Preference and Sex Differentiation in African Catfish, Clarias gariepinus
Santi, Saïdou; Rougeot, Carole ULg; Toguyeni, Aboubacar et al

in Journal of Experimental Zoology. Part A, Ecological Genetics and Physiology (2017)

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 ... [more ▼]

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 (36.5°C) in African water points, we aimed to determine the thermal preference of sexually undifferentiated juveniles and investigate if they spontaneously move toward high masculinizing temperature. Experiments were carried out in an environmental continuum (28–28–28°C and 28–32–36.5°C) made up of three 50-L aquariums connected together. Four hundred larvae from 10 different full-sib progenies were reared successively from 2 to 14 dph in these facilities. Before and after thermal treatments, fish were reared at 28°C until sex ratio determination at 70 dph. In the control continuum, fish were nearly equally distributed in the three compartments. Conversely, in the thermal continuum, compartment occupation significantly differed with progeny and period. During the highly thermosensitive period, two of five progenies significantly preferred (54.7% and 39.8% occupation) the 36.5°C compartment. All tested progenies reared in thermal continuum and separated 36.5°C aquarium showed a skewed sex ratio toward the male phenotype (78–100%). Nevertheless, no correlation was found between 36.5°C compartment occupation and sex ratio in thermal continuum groups. As masculinization temperature could be encountered in African water points during the spawning season, we discussed the adaptive advantage for the African catfish to display a sex differentiation process controlled by a temperature effect. [less ▲]

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See detailEtude comparative des performances zootechniques d'une souche domestiquée de Clarias gariepinus (Burchell, 1822) et d'une souche sauvage de Clarias anguillaris (Linnaeus, 1758).
Compaore, Inoussa; Toguyeni, Aboubacar; Rougeot, Carole ULg et al

in International Journal of Biological and Chemical Sciences (2016), 10(5), 2138-2150

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See detailThermosensitivity of the sex differentiation process in the African catfish, Clarias gariepinus: Determination of the thermosensitive period
Santi, Saïdou ULg; Gennotte, Vincent ULg; Toguyeni, Aboubacar et al

in Aquaculture (2016), 455

Gonadal sex differentiation in gonochoristic fish is generally labile and under the control of two interacting processes: genetic sex determination (GSD) and environmental sex determination (ESD ... [more ▼]

Gonadal sex differentiation in gonochoristic fish is generally labile and under the control of two interacting processes: genetic sex determination (GSD) and environmental sex determination (ESD). Numerous experimental studies deal with temperature induced-sex differentiation in teleosts, but none focused on the African catfish Clarias gariepinus. The aim of this study was to confirm the thermosensitivity of the sex differentiation process and to determine the thermosensitive period during the African catfish development. Fish were exposed to high temperature (36 °C) for 3 days at different periods during ontogenesis. The treatment was applied every 3 days from fertilization until 29 days post-hatching (dph). Before and after the thermal treatment, fish were reared at 28 °C. Gonadal development was histologically characterized on fish sampled at 10, 15, 20, 25, 35, 45, 55 and 70 dph. Our results demonstrated that the African catfish displays a thermosensitivity of the sex differentiation process, with a masculinizing effect of high temperature (36 °C). The most thermosensitive period extended from 6 to 8 dph. Fish batches exposed to 36 °C during this period showed a sex-ratio skewed towards the male phenotype, ranging from 58 to 100% (high inter-familial variability). The African catfish gonads (male and female) stayed histologically undifferentiated until 20 dph. Obvious signs of gonadal differentiation clearly appeared at 25 dph in females and at 45 dph in males. Variability in sex-ratios between progenies and in the response to thermal treatment suggests a role of minor genetic factors and interactions between genomic and environmental determinants in the expression of the sexual phenotype. Statement of relevance: 1. This paper provides novel methods to control African catfish Clarias gariepinus sex differentiation through high temperature exposure and then to produce all-male populations. 2. Our work underlines the possibility to significantly reduce high temperature (masculinizing effect) treatment period to 3 days and consequently increase survival rate of progenies after treatment. 3. This study also shows the inter-family variability of thermosensitivity on the sex differentiation process in Clarias gariepinus. [less ▲]

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See detailMorphometric and Meristic Identification of Wild Populations of Clarias sp and their Hydro-geographical Structuring in Burkina Faso
Compaoré, Inoussa; Toguyéni, Aboubacar; Rougeot, Carole ULg et al

in American Journal of Agricultural Science (2015), 2(6)

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See detailFish as aquatic "sniffer dogs": Olfactory-mediated behaviors and conditioning of common carps to cadaver odors
Jamandre, Brian Wade ULg; Ferrari, Frederic; Joseph, Jean-Ronald et al

Conference (2015, September)

Even with the aide of modern technology, the search for cadaver or human remains underwater is still assisted by sniffer dogs mainly because of their superior sense of olfaction. However, dogs rely on ... [more ▼]

Even with the aide of modern technology, the search for cadaver or human remains underwater is still assisted by sniffer dogs mainly because of their superior sense of olfaction. However, dogs rely on volatile organic compounds in the air and that this may constraint their ability when searching for submerged cadavers. On the other hand, it has long been recognized that fishes use olfaction to sample odors from their surroundings to accomplish a task and are capable of acquiring new skills through training or conditioning. Despite decades of experimental and observational studies of the olfactory sensitivities of fishes, its potential application to forensic sciences has never been truly explored. In this pioneering research, we explore the possibility of using fish olfaction in detecting cadaver odors (porcine origin), using common carps Cyprinus carpio as model species in a series of experiments under laboratory conditions. We first observed the innate behavior of carps towards cadaver odors. Afterwards, the carps were trained in two-choice chamber experimental tanks by appetitive olfactory conditioning and odor masking methods. We also experimented on the effects of cadaver odors by early exposure using eggs and larval impregnation techniques, and observing the behaviors when they develop to early juveniles. In general, we found out that common carps are naturally repelled to cadaver odors. However using our devised conditioning protocol, results show that the conditioned carps were able to learn to be attracted to cadaver odors despite their innate aversion. The development of fish for cadaver detection is a simple but innovative idea and that it may present a cost-effective and reliable solution for the shortcomings of the existing methods in underwater cadaver search. We anticipate that this research will open up a variety of different studies in pursuit of developing fishes as biosensors and its application to forensic sciences. [less ▲]

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See detailBrief exposure of embryos to steroids or aromatase inhibitor induces sex reversal in Nile tilapia (Oreochromis niloticus)
Gennotte, Vincent ULg; Mafwila Kinkela, Patrick ULg; Ulysse, Bernard et al

in Journal of Experimental Zoology. Part A, Ecological Genetics and Physiology (2015), 323

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 ... [more ▼]

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-h immersion applied between 1 and 36 h post-fertilization (hpf). Concentrations of active substances were 1000 or 2000 µg l-1 in XX and XY, and 2000 or 6500 µg l-1 in YY. Masculinizing treatments of XX embryos achieved a maximal sex reversal rate of 10 % with an exposure at 24 hpf to 1000 µg l-1 of 11-ketotestosterone or to 2000 µg l-1 of Fadrozole. Feminization of XY embryos was more efficient and induced up to 91 % sex reversal with an exposure to 2000 µg l-1 of 17α-ethynylestradiol. Interestingly, similar treatments failed to reverse YY fish to females, suggesting either that a sex determinant linked to the Y chromosome prevents the female pathway when present in two copies, or that a gene present on the X chromosome is needed for the development of a female phenotype. [less ▲]

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See detailChapter 24: Performances of Hybrid Percid
Held, James A.; Mandiki, Syaghalirwa N.M; Rougeot, Carole ULg et al

in Biology and Culture of Percid Fishes - Principles and Practices. (2015)

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See detailChapter 23. Sex And Ploidy Manipulation in Percid Fish.
Rougeot, Carole ULg

in Kestemont, Patrick; Dabrowski, Konrad; Summerfelt, RC (Eds.) Biology and Culture of Percid Fishes - Principles and Practices. (2015)

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See detailSex determinism in Fish - the Belgian team case studies
Rougeot, Carole ULg; Gennotte, Vincent ULg; Santi, Saïdou ULg et al

Conference (2014, September 22)

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See detailThe sensitive period for male-to-female sex reversal begins at the embryonic stage in the Nile tilapia and is associated with the sexual genotype
Gennotte, Vincent ULg; Mélard, Charles ULg; D'Cotta, Helena et al

in Molecular Reproduction and Development (2014), 81

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 mg L-1) and YY (6500 mg L-1) Nile tilapia ... [more ▼]

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 mg L-1) and YY (6500 mg 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%. These results, together with the clearance profile of 17α-ethynylestradiol, confirmed the existence of an early sensitive period for sex determination that encompasses embryonic and larval development and is active prior to any sign of gonad differentiation. Estrogen treatment induced elevated expression of cyp19a1b and higher testosterone and 17β-estradiol concentrations at 4 dpf in both XY and YY individuals. foxl2 and amh were repressed at 4 dpf and their expression levels were not different between treated and control groups at 14 dpf, suggesting that foxl2 did not control cyp19a1b in the brains of tilapia embryos. Increased cyp19a1b expression in treated embryos could reflect early brain sexualization, although this difference alone cannot account for the observed sex reversal as the treatment was ineffective in YY individuals. The differential sensitivity of XY and YY genotypes to embryonic induced-feminization suggests that a sex determinant on the sex chromosomes, such as a Y repressor or an X activator, may influence sex reversal during the first steps of tilapia embryogenesis. [less ▲]

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See detailInfluence of domestication process on immune response to repeated emersion stressors in Eurasian perch (Perca fluviatilis L.)
Douxfils, Jessica; Lambert, S; Mathieu, Cédric et al

in Comparative Biochemistry and Physiology. A : Comparative Physiology (2014), 173

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See detailIMMUNE AND NEURO-ENDOCRINE RESPONSES OF GRAVID EURASIAN PERCH TO CHRONIC CONFINEMENT AND SOCIAL ISOLATION STRESS
Mandiki, SMN; Douxfils, Jessica; Massart, Sophie et al

Poster (2013, June)

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See detailCortisol is responsible for positive and negative effects in the ovarian maturation induced by the exposure to acute stressors in Nile tilapia, Oreochromis niloticus
Gennotte, Vincent ULg; Sawadogo, Philippe; Milla, Sylvain et al

in Fish Physiology and Biochemistry (2012), 38

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See detailSperm quality analysis in XX, XY and YY males of the Nile tilapia (Oreochromis niloticus).
Gennotte, Vincent ULg; François, Ekniel; Rougeot, Carole ULg et al

in Theriogenology (2012)

In Nile tilapia (Oreochromis niloticus), individuals with atypical sexual genotype are commonly used in farming (use of YY males to produce all-male offsprings), but they also constitute major tools to ... [more ▼]

In Nile tilapia (Oreochromis niloticus), individuals with atypical sexual genotype are commonly used in farming (use of YY males to produce all-male offsprings), but they also constitute major tools to study sex determinism mechanisms. In other species, sexual genotype and sex reversal procedures affect different aspects of biology such as growth, behaviour and reproductive success. The aim of this study was to assess the influence of sexual genotype on sperm quality in Nile tilapia. Milt characteristics were compared in XX (sex-reversed), XY and YY males in terms of gonadosomatic index, sperm count, sperm motility and duration of sperm motility. Sperm motility was measured by computer-assisted sperm analysis (CASA) quantifying several parameters: total motility, progressive motility, curvilinear velocity, straight line velocity, average path velocity and linearity. None of the sperm trait measured differed significantly between the three genotypes. Mean values of gonadosomatic index, sperm concentration and sperm motility duration of XX, XY and YY males respectively ranged from 0.92 to 1.33 %, from 1.69 to 2.22 × 10(9) cells mL-1 and from 18’04’’ to 27’32’’. Mean values of total motility and curvilinear velocity 1 min after sperm activation respectively ranged from 53 to 58 % and from 71 to 76 µm s-1 for the three genotypes. After 3 min of activity, all the sperm motility and velocity parameters dropped by half and continued to slowly decrease thereafter. Seven min after activation, only 9 to 13 % of spermatozoa were still progressive. Our results prove that neither sexual genotype nor hormonal sex reversal treatments affect sperm quality in male Nile tilapias with atypical sexual genotype. [less ▲]

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See detailPhysiological and proteomic evidences that domestication process differentially modulates the immune status of juvenile Eurasian perch (Perca fluviatilis) under chronic confinement stress.
Douxfils, J.; Mathieu, Cédric; Mandiki, S. N. et al

in Fish and Shellfish Immunology (2011), 159(1), 92-9

The current study aimed to evaluate the influence of domestication process on the stress response and subsequent immune modulation in Eurasian perch juveniles (Perca fluviatilis) submitted to chronic ... [more ▼]

The current study aimed to evaluate the influence of domestication process on the stress response and subsequent immune modulation in Eurasian perch juveniles (Perca fluviatilis) submitted to chronic confinement. Briefly, F1 and F4 generations were confined into small-size tanks and sampled 7 and 55 days after stocking. Cortisol and glucose levels as well as lysozyme activity and immunoglobulin level were evaluated in the serum. Spleen Somatic Index and spleen ROS production were also measured. A proteomic analysis was performed on serum sampled on day 7. Finally, both generations were genetically characterized using a microsatellite approach. Globally, results revealed that chronic confinement did not elicit a typical stress response but resulted in a prolonged immune stimulation. Proteomic results suggested that domestication process influenced the immune status of perch submitted to chronic confinement as the F1 confined fish displayed lower abundance of C3 complement component, transferrin and Apolipoprotein E. Microsatellite data showed a strong genetic drift as well as reduced genetic diversity, allelic number and heterozygosity along with domestication process. The present work is the first to report that fish under domestication can develop an immune response, assessed by a combined approach, following recurrent challenges imposed by captive environment despite a reduced genetic variation. [less ▲]

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