Avancées récentes concernant l'utilisation de l'IRM pour l'amélioration génétique des espèces piscicoles

[Departement_IRSTEA]Ecotechnologies [TR1_IRSTEA]SPEENational audienceL'utilisation d'un scanner IRM pour l'analyse d'un grand nombre d'échantillons de poissons (1000) a permis d'estimer l'héritabilité du taux de lipide de la chair dans le cadre d'un projet d'évaluation généalogique assistée par empreintes génétiques pour les programmes de sélection de la filière truiticole

Le programme Fil Dor : associer sélection génétique et analyse d’impact environnemental des élevages de poissons

International audienceÀ l’échelle mondiale, la pisciculture est le domaine de production animale qui présente la plus forte croissance, de l’ordre de 10 % par an (FAO, 2012). Elle répond une hausse de la demande en produits aquatiques que ne peut satisfaire la pêche, dont les débarquements stagnent. Tout comme les autres systèmes de production agricole, la pisciculture vise un mode de développement durable, conciliant le respect de l’environnement, les attentes sociales et économiques des producteurs, des autres acteurs de la filière et des populations locales

Rapid quantification of muscle fat content and subcutaneous adipose tissue in fish using MRI

International audienceThe potentiality of MRI to quantify fat content in flesh and subcutaneous fat in fish cutlets was investigated. Low measurement time was aimed at in a view to handling large number of samples needed in selective breeding programs for example. Results on fresh and frozen-thawed cutlets were compared to assess this way of conservation. As MRI generates unwanted spatial variations of the signal, a correction method was developed enabling the measurement on several cutlets simultaneously in less than 3 min per sample. For subcutaneous fat, the results were compared with vision measurements. High correlations between both techniques were found (R2 = 0.77 and 0.87 for the ventral and dorsal part). Fat in flesh was validated vs NMR measurements. No statistical difference was found between fresh and frozen-thawed cutlets. RMSE was respectively 0.8% and 0.89%. These results confirmed the potentiality of MRI for fat measurement in fish particularly for a large number of samples

Reprint of: Genetic parameters of in-vivo prediction of carcass, head and fillet yields by internal ultrasound and 2D external imagery in large rainbow trout [i](Oncorhynchus mykiss)[/i]

Voir aussi : Pierrick Haffray, Jérome Bugeon, Quentin Rivard, Benjamin Quittet, Sophie Puyo, Jean Michel Allamelou, Marc Vandeputte, Mathilde Dupont-Nivet. 2013. Genetic parameters of in-vivo prediction of carcass, head and fillet yields by internal ultrasound and 2D external imagery in large rainbow trout (Oncorhynchus mykiss). Aquaculture (410–411), 236-244Selection to improve processing yields relies on sib selection, in which live candidates are ranked according to their family breeding value. This approach limits genetic progress, as it only exploits genetic variability between families and not within them. Indirect criteria measured on live candidates could overcome this limitation. The present study (1) proposes a procedure to identify indirect criteria to predict processing yields in rainbow trout (head, carcass and fillet yields), (2) estimates genetic parameters of these indirect criteria, and (3) predicts relative genetic gains in processing yields using full-sib selection or indirect individual selection on those indirect criteria. DNA-pedigreed all-female rainbow trout Oncorhynchus mykiss (n = 2029, 1631.0 ± 355.6 g) from 600 families produced from 100 sires and 60 dams were characterized by external and internal non-lethal morphological measures using digital pictures and real time ultrasound tomography. Nineteen landmarks were recorded on the digital pictures to define the outline of the body, head and lateral line. Their coordinates were used to calculate different lengths, heights and areas. Five different internal thicknesses were measured by ultrasound tomography. In the first phase of this study, processing yields were predicted using multiple linear regressions including both external and internal morphometric variables. In a second phase, the heritability of the predicted values and their genetic correlations with real processing yields were estimated using animal models. Predicted yields exhibited intermediate heritabilities (0.25–0.28) that were half the value of heritabilities for real processing yields (0.47–0.55), but had high genetic correlations with these real yields (0.87–0.90). The relative efficiency of indirect selection (IS) on these indirect criteria was compared to theoretical mass selection (MS) or sib selection (FS) with different family sizes (10 or 100) and two different selection pressures (10% or 40%). At the same selection pressure (10%, with 100 sibs per family %), full-sib selection created genetic progress 49.6% to 60.5% higher than indirect selection according to the processing yield targeted. However, when sib-selection pressure was limited to a more realistic between family selection pressure (40% and 10 sibs per family), indirect selection with 10% selection pressure was 21.9% to 32.7% more efficient than sib selection

"Qualitytruite" : l'IRM comme méthode de quantification rapide du gras intramusculaire et du tissu adipeux sous cutané des darnes de truite arc-en-ciel (Oncorhynchus mykiss)

Le but du projet était d’évaluer chez la truite arc-en-ciel la faisabilité du dosage de la teneur en lipides intramusculaires et de la surface de gras sous cutané par Imagerie en Résonance Magnétique (IRM) sur des darnes entières après décongélation. La possibilité d’analyser plusieurs darnes simultanément dans l’IRM a été validée en utilisant un support spécifique pour disposer les darnes au sein de l’imageur. Un modèle de correction du signal permet de pallier l’inhomogénéité du signal dans l’espace de mesure. La comparaison de la teneur en lipides de darnes fraîches et décongelées avec un dosage RMN met en évidence de très bonnes corrélations avec une erreur moyenne de 0.8 et 0.89% respectivement. Ce qui démontre que la congélation ne dégrade pas la précision du dosage. La surface de gras sous cutané mesurée en IRM et en vision numérique présente de bonnes corrélations R²=0.77 et 0.87 respectivement pour les tissus adipeux ventraux et dorsaux

Genetic parameters of in-vivo prediction of carcass, head and fillet yields by internal ultrasound and 2D external imagery in large rainbow trout (Oncorhynchus mykiss)

Selection to improve processing yields relies on sib selection, in which live candidates are ranked according to their family breeding value. This approach limits genetic progress, as it only exploits genetic variability between families and not within them. Indirect criteria measured on live candidates could overcome this limitation. The present study (1) proposes a procedure to identify indirect criteria to predict processing yields in rainbow trout (head, carcass and fillet yields), (2) estimates genetic parameters of these indirect criteria, and (3) predicts relative genetic gains in processing yields using full-sib selection or indirect individual selection on those indirect criteria. DNA-pedigreed all-female rainbow trout Oncorhynchus mykiss (n = 2029, 1631.0 +/- 355.6 g) from 600 families produced from 100 sires and 60 dams were characterized by external and internal non-lethal morphological measures using digital pictures and real time ultrasound tomography. Nineteen landmarks were recorded on the digital pictures to define the outline of the body, head and lateral line. Their coordinates were used to calculate different lengths, heights and areas. Five different internal thicknesses were measured by ultrasound tomography. In the first phase of this study, processing yields were predicted using multiple linear regressions including both external and internal morphometric variables. In a second phase, the heritability of the predicted values and their genetic correlations with real processing yields were estimated using animal models. Predicted yields exhibited intermediate heritabilities (0.25-0.28) that were half the value of heritabilities for real processing yields (0.47-0.55), but had high genetic correlations with these real yields (0.87-0.90). The relative efficiency of indirect selection (IS) on these indirect criteria was compared to theoretical mass selection (MS) or sib selection (FS) with different family sizes (10 or 100) and two different selection pressures (10% or 40%). At the same selection pressure (10%, with 100 sibs per family %), full-sib selection created genetic progress 49.6% to 60.5% higher than indirect selection according to the processing yield targeted. However, when sib-selection pressure was limited to a more realistic between family selection pressure (40% and 10 sibs per family), indirect selection with 10% selection pressure was 21.9% to 32.7% more efficient than sib selection

Survival, Growth and Reproduction of Cryopreserved Larvae from a Marine Invertebrate, the Pacific Oyster (Crassostrea gigas)

This study is the first demonstration of successful post-thawing development to reproduction stage of diploid cryopreserved larvae in an aquatic invertebrate. Survival, growth and reproductive performances were studied in juvenile and adult Pacific oysters grown from cryopreserved embryos. Cryopreservation was performed at three early stages: trochophore (13 +/- 2 hours post fertilization: hpf), early D-larvae (24 +/- 2 hpf) and late D-larvae (43 +/- 2 hpf). From the beginning (88 days) at the end of the ongrowing phase (195 days), no mortality was recorded and mean body weights did not differ between the thawed oysters and the control. At the end of the growing-out phase (982 days), survival of the oysters cryopreserved at 13 +/- 2 hpf and at 43 +/- 2 hpf was significantly higher (P<0.001) than those of the control (non cryopreserved larvae). Only the batches cryopreserved at 24 +/- 2 hpf showed lower survival than the control. Reproductive integrity of the mature oysters, formely cryopreserved at 13 +/- 2 hpf and 24 +/- 2 hpf, was estimated by the sperm movement and the larval development of their offspring in 13 crosses gamete pools (five males and five females in each pool). In all but two crosses out of 13 tested (P<0.001), development rates of the offspring were not significantly different between frozen and unfrozen parents. In all, the growth and reproductive performances of oysters formerly cryopreserved at larval stages are close to those of controls. Furthermore, these performances did not differ between the three initial larval stages of cryopreservation. The utility of larvae cryopreservation is discussed and compared with the cryopreservation of gametes as a technique for selection programs and shellfish cryobanking

PET Adapted Salvage Therapy for Advanced Hodgkin Lymphomas: Towards the Suppression of Positive Interim PET Unfavorable Prognosis? a Report of the Goelams Multicentric Phase 2 Trial LH2007

WOS:000368021800189International audience55th Annual Meeting and Exposition of the American-Society-of-Hematology - New Orleans, LA 201

PET Adapted Salvage Therapy for Advanced Hodgkin Lymphomas: Towards the Suppression of Positive Interim PET Unfavorable Prognosis? a Report of the Goelams Multicentric Phase 2 Trial LH2007

WOS:000368021800189International audience55th Annual Meeting and Exposition of the American-Society-of-Hematology - New Orleans, LA 201

Cryopreservation of Pacific oyster (Crassostrea gigas) larvae: Revisiting the practical limitations and scaling up the procedure for application to hatchery

International audiencePacific oyster Crassostrea gigas is one major species for aquaculture, and the development of breeding programs and the need for preservation of wild stock genetic resources prompted the need for larvae cryopreservation. The objective of the present study was to choose the most reliable protocol from several existing publications, to test its biological and practical limitations, and to adapt it to hatchery conditions. The selected protocol was characterized by a very slow freezing rate without seeding, and by the use of ethylene glycol and sucrose as cryoprotectant. The best survivals after thawing and rearing up to 48 h post fertilization (hpf) were obtained with larvae that were frozen at late trochophore (20 hpf) and early-D (24 hpf) stages. Increasing the larvae concentration in the straws and using high throughput straw filling and freezing devices did not alter the cryopreservation outcome. The whole procedure was applied to cryopreservation in a commercial hatchery (Satmar, France), and the thawed larvae yielded 9.4 ± 4.5% survivals at 12 days post fertilization. The overall success was dampened by some variability in the larvae survival that is likely due to the physiological status of the larvae. In all, the proposed procedure is robust and reliable and can be used for cryobanking of oyster genetic resources