title: Metabolic and histochemical characteristics of fat and muscle tissues in homozygous or heterozygous pigs for the body composition QTL located on chromosome 7.
abstract: Quantitative trait loci (QTL) influencing many traits including backfat thickness and carcass composition have been detected on porcine chromosome 7 (SSC7) in an F2 cross between Large White (LW) and Meishan (MS) pigs. However, the genes and controlled pathways underlying the QTL effects on body phenotype remain unknown. This study aimed at investigating the tissue characteristics at metabolic and cellular levels in pigs that were either homozygous or heterozygous for a body composition SSC7 QTL. A backcross pig (BC3) was first progeny tested to confirm its heterozygoty for the SSC7 QTL; results on all offspring (n = 80) confirmed the QTL effects on body fatness. This boar was then mated with three sows known to be heterozygous for this QTL. In the subset of pigs per genotype, we found that heterozygous LW(QTL7)/MS(QTL7) pigs had smaller adipocytes in backfat, together with a lower basal rate of glucose incorporation into lipids and lower activities of selected lipogenic enzymes in backfat isolated cells, compared with homozygous LW(QTL7)/LW(QTL7) pigs. A higher number of adipocytes was also estimated in backfat of LW(QTL7)/MS(QTL7) animals compared with LW(QTL7)/LW(QTL7) pigs. The SSC7 QTL did not influence oxidative and glycolytic metabolisms of longissimus and trapezius muscles, as estimated by the activities of specific energy metabolism enzymes, or the myofiber type properties. Altogether, this study provides new evidence for an altered adipocyte cellularity in backfat of pigs carrying at least one MS allele for the SSC7 QTL. Some candidate genes known for their functions on adipocyte growth and differentiation are suggested.
authors.affiliation: Institut National de la Recherche Agronomique, Unité Mixte de Recherche 444, Laboratoire de Génétique Cellulaire, BP52627, Castanet-Tolosan, France .
authors.forename: Julie
authors.initials: J
authors.lastname: Demars
authors.forename: Juliette
authors.initials: J
authors.lastname: Riquet
authors.forename: Marie-Pierre
authors.initials: MP
authors.lastname: Sanchez
authors.forename: Yvon
authors.initials: Y
authors.lastname: Billon
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Hocquette
authors.forename: Bénédicte
authors.initials: B
authors.lastname: Lebret
authors.forename: Nathalie
authors.initials: N
authors.lastname: Iannuccelli
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Bidanel
authors.forename: Denis
authors.initials: D
authors.lastname: Milan
authors.forename: Florence
authors.initials: F
authors.lastname: Gondret
mesh_terms: D000273:Adipose Tissue / Q000033:anatomy & histology* / Q000378:metabolism*; D000818:Animals; D001823:Body Composition / Q000235:genetics*; D033481:Chromosomes, Mammalian; D005260:Female; D016013:Likelihood Functions; D008055:Lipids / Q000235:genetics; D008297:Male; D018482:Muscle, Skeletal / Q000033:anatomy & histology* / Q000378:metabolism*; D010375:Pedigree; D010641:Phenotype; D040641:Quantitative Trait Loci; D013552:Swine / Q000235:genetics*
chemical_list: D008055:Lipids