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32 results on '"Chevassus Bernard"'

1. Enhanced individual selection for selecting fast growing fish: the 'PROSPER' method, with application on brown trout (Salmo trutta fario)

Author

Vandeputte Marc, Hiseux Jean-Pierre, Fauré André, Labbé Laurent, Mambrini Muriel, Hollebecq Marie-Gwénola, Krieg Francine, Quillet Edwige, and Chevassus Bernard

Subjects
Salmo trutta, selective breeding, aquaculture, genetics, individual selection, Animal culture, SF1-1100, Genetics, QH426-470
Abstract

Abstract Growth rate is the main breeding goal of fish breeders, but individual selection has often shown poor responses in fish species. The PROSPER method was developed to overcome possible factors that may contribute to this low success, using (1) a variable base population and high number of breeders (Ne > 100), (2) selection within groups with low non-genetic effects and (3) repeated growth challenges. Using calculations, we show that individual selection within groups, with appropriate management of maternal effects, can be superior to mass selection as soon as the maternal effect ratio exceeds 0.15, when heritability is 0.25. Practically, brown trout were selected on length at the age of one year with the PROSPER method. The genetic gain was evaluated against an unselected control line. After four generations, the mean response per generation in length at one year was 6.2% of the control mean, while the mean correlated response in weight was 21.5% of the control mean per generation. At the 4th generation, selected fish also appeared to be leaner than control fish when compared at the same size, and the response on weight was maximal (≈130% of the control mean) between 386 and 470 days post fertilisation. This high response is promising, however, the key points of the method have to be investigated in more detail.

Published
2004
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12. Microsatellites Cross-Species Amplification across Some African Cichlids

Author

Bezault, Etienne, Rognon, François, Gharbi, Karim, Baroiller, Jean-François, Chevassus, Bernard, Bezault, Etienne, Rognon, François, Gharbi, Karim, Baroiller, Jean-François, and Chevassus, Bernard

Abstract

The transfer of the genomic resources developed in the Nile tilapia, Oreochromis niloticus, to other Tilapiines sensu lato and African cichlid would provide new possibilities to study this amazing group from genetics, ecology, evolution, aquaculture, and conservation point of view. We tested the cross-species amplification of 32 O. niloticus microsatellite markers in a panel of 15 species from 5 different African cichlid tribes: Oreochromines (Oreochromis, Sarotherodon), Boreotilapiines (Tilapia), Chromidotilapines, Hemichromines, and Haplochromines. Amplification was successfully observed for 29 markers (91%), with a frequency of polymorphic (P95) loci per species around 70%. The mean number of alleles per locus and species was 3.2 but varied from 3.7 within Oreochromis species to 1.6 within the nontilapia species. The high level of cross-species amplification and polymorphism of the microsatellite markers tested in this study provides powerful tools for a wide range of molecular genetic studies within tilapia species as well as for other African cichlids.

Published
2012

13. Analysis of the Meiotic Segregation in Intergeneric Hybrids of Tilapias

Author

Bezault, Etienne, Rognon, François, Clota, Frédéric, Gharbi, Karim, Baroiller, Jean-François, Chevassus, Bernard, Bezault, Etienne, Rognon, François, Clota, Frédéric, Gharbi, Karim, Baroiller, Jean-François, and Chevassus, Bernard

Abstract

Tilapia species exhibit a large ecological diversity and an important propensity to interspecific hybridisation. This has been shown in the wild and used in aquaculture. However, despite its important evolutionary implications, few studies have focused on the analysis of hybrid genomes and their meiotic segregation. Intergeneric hybrids between Oreochromis niloticus and Sarotherodon melanotheron, two species highly differentiated genetically, ecologically, and behaviourally, were produced experimentally. The meiotic segregation of these hybrids was analysed in reciprocal second generation hybrid (F2) and backcross families and compared to the meiosis of both parental species, using a panel of 30 microsatellite markers. Hybrid meioses showed segregation in accordance to Mendelian expectations, independent from sex and the direction of crosses. In addition, we observed a conservation of linkage associations between markers, which suggests a relatively similar genome structure between the two parental species and the apparent lack of postzygotic incompatibility, despite their important divergence. These results provide genomics insights into the relative ease of hybridisation within cichlid species when prezygotic barriers are disrupted. Overall our results support the hypothesis that hybridisation may have played an important role in the evolution and diversification of cichlids.

Published
2012

18. L'Institut national de la recherche agronomique et l'environnement

Author

Chevassus, Bernard, Legrand, Patrick, MAYER, Pierre-Henri, and France Nature Environnement (FNE)

Subjects
[SDE.ES] Environmental Sciences/Environmental and Society, [SDE.ES]Environmental Sciences/Environmental and Society
Abstract

International audience; Deux des neuf missions dévolues à l'INRA par le décret qui en 1984, en fit un Etablissement Public à caractère Scientifique et Technique touchent à des questions d'environnement.Font en effet explicitement partie des compétences de l'Institut :- l'inventaire des ressources du milieu physique (sol, microclimat et réserves hydriques) et l'étude de leur exploitation,- la protection, la sauvegarde et la gestion rationnelle des ressources naturelles et de l'espace rural.Dans le contexte actuel, l'INRA se devait de présenter la façon dont il remplit ces missions et les perspectives de l'évolution de son investissement dans le domaine de l'environnement.

Published
1990

25. Enhanced individual selection for selecting fast growing fish: the ”PROSPER” method, with application on brown trout (Salmo trutta fario</it>)

Author

Chevassus, Bernard, Quillet, Edwige, Krieg, Francine, Hollebecq, Marie-Gwénola, Mambrini, Muriel, Fauré, André, Labbé, Laurent, Hiseux, Jean-Pierre, and Vandeputte, Marc

Abstract

Growth rate is the main breeding goal of fish breeders, but individual selection has often shown poor responses in fish species. The PROSPER method was developed to overcome possible factors that may contribute to this low success, using ([see full textsee full text]) a variable base population and high number of breeders ($Ne >100$), ([see full textsee full text]) selection within groups with low non-genetic effects and (3) repeated growth challenges. Using calculations, we show that individual selection within groups, with appropriate management of maternal effects, can be superior to mass selection as soon as the maternal effect ratio exceeds 0.15, when heritability is 0.25. Practically, brown trout were selected on length at the age of one year with the PROSPER method. The genetic gain was evaluated against an unselected control line. After four generations, the mean response per generation in length at one year was 6.2% of the control mean, while the mean correlated response in weight was 21.5% of the control mean per generation. At the 4th generation, selected fish also appeared to be leaner than control fish when compared at the same size, and the response on weight was maximal ($\approx$130% of the control mean) between 386 and 470 days post fertilisation. This high response is promising, however, the key points of the method have to be investigated in more detail.

Published
2004

26. Performances of auto and allotriploids in salmonids I. Survival and growth in fresh water farming

Author

Quillet, Edwige, Chevassus, Bernard, Blanc, Jean-Marie, Krieg, Francine, and Chourrout, Daniel

Abstract

Survival and growth performances of autotriploids in rainbow trout (Salmo gairdneri) and three types of triploid hybrids between female rainbow trout and brown trout males (Salmo trutta,) coho salmon males (Oncorhynchus kisutch) and brook trout males (Salvelinus fontinalis) were analysed relatively to the parental species in freshwater farming conditions. At the end of the immature period, autotriploids exhibit moderate but significant depression relative to the control for both survival (about 25% depression) and growth (10 to 15% depression). Most of this depression is established during the first three months of life, triploids appearing very similar to the control later on. At the onset of sexual maturation at 2 years old, relative value of triploids becomes higher than that of the control, for both survival and growth. Long term evaluation (2+or 3+) balances in favor of triploids with particular advantage for triploid females. Triploid hybrids exhibit much more important depression in early survival (up to 60%). Later on, their survival remains always lower than those of parental controls. Their growth performances are intermediate between their two parental species. Despite a relative advantage for these groups during the onset of sexual maturation in control groups, especially for growth, long tem evaluation is in favor of diploid rainbow trout, but in some specific cases.

Published
1988
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28. Effect of methyltestosterone on sex differentiation and gonad morphogenesis in rainbow trout Oncorhynchus mykiss

Author

Cousin-Gerber, Michelle, Burger, Georges, Boisseau, Claude, and Chevassus, Bernard

Abstract

Oncorhynchus mykiss alevins originating from a monosex female population were treated with methyltestosterone incorporated in the diet (0.5 or 3 mg/kg) for 60 or 90 days from the beginning of first feeding. At sexual maturity the percentage masculinization achieved was high (89-98%) whatever the concentration or duration of treatment. However, the hormone concentration was the major factor in determining the frequency of functional males obtained. Of the 2-year-old neomales produced by the treatment with 0.5 mg/kg diet for 60 days 82% were able to emit their sperm under abdominal pressure compared to only 36% of those produced with 3 mg for 60 days. The increase in the duration of treatment also resulted in a decrease in the number of functional males from 82% (0.5 mg/60 days) to 72.6% (0.5 mg/90 days) and from 35.6% (3 mg/60 days) to 19.2% (3 mg/90 days). It is therefore recommended to use a low dose of hormone (0.5 mg/kg) for only 60 days to get a high proportion of functional males.

Published
1989
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29. Déterminisme génétique du nombre de cæca pyloriques chez la truite fario (Salmo Trutta, Linné) et la Truite arc-en-ciel (Salmo Gairdneri, Richardson) III. - Effet du génotype et de la taille des œufs sur la réalisation du caractère chez la Truite fario

Author

Blanc, J.M., Chevassus, Bernard, and Bergot, P.

Subjects
GENETIQUE ANIMALE, EFFET DU GENOTYPE, caeca pylorique, truite fario, pisciculture, variété de truite, truite arc en ciel
Abstract

L’analyse de la variation du nombre de caeca pyloriques chez la Truite fario élevée en pisciculture a montré que : - le sexe des animaux n’a aucune influence significative; - une part importante de variabilité est d’origine génétique additive (héritabilité approximative 0,4); - il existe un effet maternel inhérent à la taille des œufs, les alevins issus de gros œufs tendant à avoir des nombres de caeca élevés (corrélation + 0,5);- enfin, l’action conjointe de ce facteur maternel et des autres facteurs génétiques et environnementaux semble comporter des effets interactifs dont l’étude plus approfondie serait utile., An analysis of the variation of the number of pyloric caeca in hatchery-reared brown trout showed that: - the sex of the animals has no significant influence; - an important part of variability is caused by additive genetic factors (approximate heritability 0.4); - there is a maternal effect which inheres to the size of eggs; alevins hatched from large eggs tend to have high numbers of caeca (correlation + 0,5)- lastly, the joined action of that maternal factor and other genetic and environmental factors apparently includes interactive effects; further studies on that point would be useful.

Published
1979

30. Déterminisme génétique du nombre de cæca pyloriques chez la Truite fario (Salmo trutta, Linné) et la Truite arc-en-ciel (Salmo gairdneri, Richardson) II. - Effet du génotype du milieu d’élevage et de l’alimentation sur la réalisation du caractère chez la Truite arc-en-ciel

Author

Chevassus, Bernard, BLANC, J.M., Bergot, Pierre, Institut National de la Recherche Agronomique (INRA), Laboratoire d'écologie des poissons et d'aménagement des pêches, and Laboratoire de nutrition des poissons

Subjects
TRUITE FARIO, [SDV.GEN]Life Sciences [q-bio]/Genetics, EFFET DU GENOTYPE, GENETIQUE ANIMALE, TRUITE ARC EN CIEL
Abstract

National audience; Four factors liable to affect the within and between-population variability of the number of pyloric caeca in Rainbow Trout were studied. After six months, no variation due to age was observed even after transferring the fishes from one fish farm to another. Rearing of fishes from the eyed-stage in two fish farms with very different mean temperatures (8 °C and 16 °C) induced a large difference between the mean number of pyloric caeca (5,55 at 8 °C; 51,0 à 16 °C). At 8 °C, a diet with a hight level of polyholosids slightly increased the number of caeca (+ 2,7 p. 100 in average) as compared to one with a high level of proteins. No effect was detected at 16 °C. Study of the progenies of crosses between parents having a known number of caeca showed a high correlation (γ = 0,92) between the mean parent and the mean of progenies. A quite high estimate was obtained for heritability ( h2 = 0,53 ± 0,07), the non-additive genetic variance being quite low. The conjoined effect of those different factors was analysed and described by alinear additive model. Therefore, it seems to be possible to obtain, by a two way selection, strains with different numbers of caeca and to analyse the effect of this trait on other quantitative ones like growth rate or nutritional parameters.; Quatre facteurs pouvant rendre compte de la variabilité intra et inter-populations du nombre de caeca pyloriques de la Truite arc-en-ciel ont été examinés. - Aucune variation liée à l’âge n’est décelable après 6 mois, même lorsque les individus sont soumis à un changement des conditions de milieu. - L’élevage des individus depuis le stade ceillé dans deux piscicultures ayant des moyennes thermiques très différentes (8 °C et 16 °C) conduit à une différence importante entre les moyennes du nombre de caeca (5,55 à 8 °C, 51,0 à 16 °C). - L’utilisation d’un aliment à forte teneur en polyholosides augmente le nombre de caeca (+ 2,7 p. 100 en moyenne) par rapport à un aliment riche en protéines dans la pisciculture à 8 °C, mais n’a pas d’effet dans l’autre pisciculture. - La réalisation de croisements entre parents ayant un nombre connu de caeca pyloriques permet de mettre en évidence une forte corrélation (γ = 0,92) entre le parent moyen et la moyenne des descendants. Une estimation assez élevée ( h2 = 0,53 ± 0,07) est obtenue pour l’héritabilité (part de la variance génétique additive dans la variance phénotypique totale). Par contre les effets génétiques non additifs semblent de faible importance. Le mode d’action conjoint de ces différents facteurs de variation a été examiné et obéit essentiellement à un modèle de type additif. Il apparaît donc possible d’obtenir rapidement par sélection divergente des lots ayant des nombres moyens de caeca différents et de préciser ainsi la liaison de ce paramètre avec d’autres caractères quantitatifs comme la croissance ou les performances nutritionnelles.

Published
1979

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