Melka, M. G. and Schenkel, F. 2010. Analysis of genetic diversity in four Canadian swine breeds using pedigree data. Can. J. Anim. Sci. 90: 331Á340. Conservation of animal genetic resources entails judicious assessment of genetic diversity as a first step. The objective of this study was to analyze the trend of within-breed genetic diversity and identify major causes of loss of genetic diversity in four swine breeds based on pedigree data. Pedigree files from Duroc (DC), Hampshire (HP), Lacombe (LC) and Landrace (LR) containing 480 191, 114 871, 51 397 and 1 080 144 records, respectively, were analyzed. Pedigree completeness, quality and depth were determined. Several parameters derived from the in-depth pedigree analyses were used to measure trends and current levels of genetic diversity. Pedigree completeness indexes of the four breeds were 90.4, 52.7, 89.6 and 96.1%, respectively. The estimated percentage of genetic diversity lost within each breed over the last three decades was approximately 3, 22, 12 and 2%, respectively. The relative proportion of genetic diversity lost due to random genetic drift in DC, HP, LC and LR was 74.5, 63.6, 72.9 and 60.0%, respectively. The estimated current effective population size for DC, HP, LC and LR was 72, 14, 36 and 125, respectively. Therefore, HP and LC have been found to have lost considerable genetic diversity, demanding priority for conservation. Key words: Genetic drift, effective population size Melka, M. G. and Schenkel, F. 2010. Analyse de la diversite´ge´ne´tiquediversite´ge´diversite´ge´ne´diversite´ge´ne´tique de quatre races de porc canadiennes a` partir des donneés ge´neálogiquesge´neálogiques. Can. J. Anim. Sci. 90: 331Á340. La pre´servationpre´servation des ressources ge´ne´tiquesge´ne´ge´ne´tiques animales suppose avant tout une e´valuatione´valuation judicieuse de la diversite´ge´ne´tiquediversite´ge´diversite´ge´ne´diversite´ge´ne´tique. L'e´tudee´tude devait analyser les tendances de la diversite´ge´ne´tiquediversite´ge´diversite´ge´ne´diversite´ge´ne´tique au sein de la race et identifier les principales raisons pour lesquelles cette diversite´sdiversite´s'amoindrit chez quatre races de porc, daprè s les donneés ge´neálogiquesge´neálogiques. A ` cette fin, les auteurs ont analyseí'ascendance des races Duroc (DC), Hampshire (HP), Lacombe (LC) et Landrace (LR) graˆcegraˆce aux dossiers contenant respectivement 480 191, 114 871, 51 397 et 1 080 144 entreés. Ils ont de´termineíade´termineía comple´tudecomple´tude, la qualiteét l'e´tenduee´tendue de la ge´neálogiege´neálogie. Plusieursparamè tres de´rive´sde´rive´de´rive´s de ces analyses approfondies ont permis de mesurer les tendances et le degreáctuel de diversite´ge´ne´tiquediversite´ge´diversite´ge´ne´diversite´ge´ne´tique. L'indice de comple´tudecomple´tude pour chacune des quatre race s'e´tablissaite´tablissait respectivement a` 90,4, 52,7, 89,6 et 96,1%. Le pourcentage de diversite´ge´ne´tiquediversite´ge´diversite´ge´ne´diversite´ge´ne´tique qu'on estime avoir perdu au sein de chaque race au cour...

Dietary preference for fat may increase risk for obesity. It is a complex behavior regulated in part by the amygdala, a brain structure involved in reward processing and food behavior, and modulated by genetic factors. Here, we conducted a genome-wide association study (GWAS) to search for gene loci associated with dietary intake of fat, and we tested whether these loci are also associated with adiposity and amygdala volume. We studied 598 adolescents (12-18 years) recruited from the French-Canadian founder population and genotyped them with 530 011 single-nucleotide polymorphisms. Fat intake was assessed with a 24-hour food recall. Adiposity was examined with anthropometry and bioimpedance. Amygdala volume was measured by magnetic resonance imaging. GWAS identified a locus of fat intake in the μ-opioid receptor gene (OPRM1, rs2281617, P=5.2 × 10(-6)), which encodes a receptor expressed in the brain-reward system and shown previously to modulate fat preference in animals. The minor OPRM1 allele appeared to have a 'protective' effect: it was associated with lower fat intake (by 4%) and lower body-fat mass (by ∼2 kg, P=0.02). Consistent with the possible amygdala-mediated inhibition of fat preference, this allele was additionally associated with higher amygdala volume (by 69 mm(3), P=0.02) and, in the carriers of this allele, amygdala volume correlated inversely with fat intake (P=0.02). Finally, OPRM1 was associated with fat intake in an independent sample of 490 young adults. In summary, OPRM1 may modulate dietary intake of fat and hence risk for obesity, and this effect may be modulated by subtle variations in the amygdala volume.

Apoptosis occurs during early development in both in vivo- and in vitro-produced embryos, and is considered as one of the causes of embryonic loss. The objectives of this study were, therefore, investigating stage-specific expression profiles of apoptosis regulatory genes in three quality groups of in vitro-produced bovine pre-implantation embryos; and analysing the relationship between cell number and DNA fragmentation with expressions of those genes. The relative abundance of mRNA of 9 pro- (Bax, caspase-9, Bcl-xs, P53, Caspase-3 and Fas) and anti- (Bcl-w and Mcl-1) apoptotic genes was analysed. Differential cell staining and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labelling were performed to analyse the variation in cell numbers and detect apoptotic nuclei respectively. Expression of Bax and Caspase-3 genes was significantly (p < 0.05) higher in poor quality pre-implantation embryos as compared with that of morphologically good quality embryos of the same developmental stages. Moreover, Mcl-1 expression was significantly higher in good quality immature oocytes than that in the poor quality group. Moreover, higher DNA fragmentation was evidenced in morphologically poor quality blastocysts. In conclusion, our study demonstrates that Bax, caspase-3 and Mcl-1 can be used as potential markers of embryo quality to evaluate in vitro-produced bovine embryos. Further studies are required to investigate specific molecular signatures that can be used in evaluating in vivo-derived embryos.