References of "Mélard, Charles"
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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; Ulysse, Bernard et al

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

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 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 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 detailLaboratory validation of a lateral flow device for the detection of CyHV-3 antigens in gill swabs
Vrancken, Robert; Boutier, Maxime ULg; Ronsmans, Maygane ULg et al

in Journal of Virological Methods (2013), 193

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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 detailEffect of feeding regimes on growth and survival of Clarias gariepinus larvae: replacement of Artemia by a commercial feed
Vandecan, M.; Diallo, A.; Mélard, Charles ULg

in Aquaculture Research (2011), 42(5), 733-736

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See detailSkin mucus of Cyprinus carpio inhibits cyprinid herpesvirus 3 binding to epidermal cells
RAJ, Victor; Fournier, Guillaume ULg; Rakus, Krzysztof ULg et al

in Veterinary Research (2011), 42(92),

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See detailElevated amh Gene Expression in the Brain of Male Tilapia (Oreochromis niloticus) during Testis Differentiation
Poonlaphdecha, S.; Soler, P.; Sheng-Hui, H. et al

in Sexual Development (2011), 5(1), 33-47

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See detailDoes domestication process affect stress response in juvenile Eurasian perch Perca fluviatilis ?
Douxfils, Jessica; Mandiki, S. N. M.; Marotte, Grégory et al

in Comparative Biochemistry and Physiology. A : Comparative Physiology (2011), 159

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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 & 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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See detailEffect of Chronic confinement stress on growth, survival, blood cortisol and glucose of perch (Perca fluviatilis)
Rougeot, Carole ULg; Tomson, Thomas; Vandecan, Michaël et al

Poster (2011)

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See detailEffect of partial or total replacement of forage fish by a dry diet on the quality of reproduction in pikeperch, Sander lucioperca
Wang, Neil; Mandiki, S. N. M.; Henrotte, Emilie et al

in Aquaculture Research (2009), 40(3), 376-383

The aim of this preliminary study was to evaluate the influence of different feeding regimes on the quality of reproduction in pikeperch. Three diets were tested: forage fish (FF), a commercial dry feed ... [more ▼]

The aim of this preliminary study was to evaluate the influence of different feeding regimes on the quality of reproduction in pikeperch. Three diets were tested: forage fish (FF), a commercial dry feed (DD) and a mix of both (FD). The diets were given to fish throughout a complete reproductive cycle. During the spawning season, couples were injected with human chorionic gonadotropin (hCG) and let to spawn on nests. Proportion of running males, spawning and hatching success and larval quality (weight, length, body protein, total lipid, fatty acid and lipid class compositions and resistances to osmotic shock and starvation stress tests at hatching) were evaluated. The proportion of running male was lower in the DD group than in the FF and FD groups (54% for DD against 76-89% for FF and FD). In addition, 25%, 62.5% and 75% of injected couples gave spawning that hatched in DD, FF and FD groups respectively. Larval quality parameters were not significantly different between treatments. The results indicate that overall quality of reproduction was higher in FF and FD treatments than in DD. It suggests that the dry feed used was not totally adequate for pikeperch reproduction. Relations between breeder reproductive performances and the feed compositions are discussed. [less ▲]

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See detailOvarian steroidogenesis inhibition by constant photothermal conditions is caused by a lack of gonadotropin stimulation in Eurasian perch
Milla, S.; Mandiki, S. N. M.; Hubermont, P. et al

in General and Comparative Endocrinology (2009), 163(3), 242-250

In fish, the reasons for the inhibition of reproduction by constant photothermal conditions of rearing are far from clear. In an in vivo experiment, two groups of females reared under natural (4-28 ... [more ▼]

In fish, the reasons for the inhibition of reproduction by constant photothermal conditions of rearing are far from clear. In an in vivo experiment, two groups of females reared under natural (4-28 degrees C) or constant photothermal conditions (20-22 degrees C, photoperiod 12/12) were investigated for gonad development, sex-steroids (testosterone-T, 17-beta-estradiol-E2 and 11 Keto-Testosterone-11KT) dynamics and brain aromatase activity in January, February and March. Two days before each sampling date, a group of females reared under constant conditions was injected with HCG (Human Chorionic Gonadotropin: 100 Ul/kg) and evaluated for the same parameters. In addition, in vitro ovarian steroidogenesis capacity for each female was determined with or without stimulation by HCG and/or IGF-1 (insulin-like Growth Factor-1). The results indicate that vitellogenesis stage is the limit ovarian stage never reached in females submitted to constant photothermal conditions. This was associated with gonadogenesis delay and low levels of circulating sex-steroids (T, E2 and 11KT). Nevertheless, HCG injections partly counteracted the plasma steroid deprivation, indicating that ovaries from fish reared under constant photothermal conditions suffer from a lack of gonadotropin stimulation, maybe caused by plasma LH suppression. Such finding was confirmed by the in vitro ovary incubation test. HCG and IGF-1 treatments induced broad testosterone and 17-beta-estradiol elevations and the exposure to constant photothermal conditions, in some cases, decreased that response to HCG. In conclusion, we show that the inhibition of reproductive cycle in Eurasian perch females by constant photothermal conditions of rearing may be related to lower sex-steroid levels and to an inhibition of ovarian regulation by gonadotropins (at least LH), probably stopping gonadogenesis before vitellogenesis stage. (C) 2009 Elsevier Inc. All rights reserved. [less ▲]

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See detailSexual dimorphism in two pure cichlid species, Oreochromis niloticus and Sarotherodon melanotheron, and their intergeneric hybrids
Toguyeni, A.; Fauconneau, B.; Mélard, Charles ULg et al

in African Journal of Aquatic Science (2009), 34

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