Test for positional candidate genes for body composition on pig chromosome 6.

One QTL affecting backfat thickness (BF), intramuscular fat content (IMF) and eye muscle area (MA) was previously localized on porcine chromosome 6 in an F2 cross between Iberian and Landrace pigs. This work was done to study the effect of two positional candidate genes on these traits: H-FABP and LEPR genes. The QTL mapping analysis was repeated with a regression method using genotypes for seven microsatellites and two PCR-RFLPs in the H-FABP and LEPR genes. H-FABP and LEPR genes were located at 85.4 and 107 cM respectively, by linkage analysis. The effects of the candidate gene polymorphisms were analyzed in two ways. When an animal model was fitted, both genes showed significant effects on fatness traits, the H-FABP polymorphism showed significant effects on IMF and MA, and the LEPR polymorphism on BF and IMF. But when the candidate gene effect was included in a QTL regression analysis these associations were not observed, suggesting that they must not be the causal mutations responsible for the effects found. Differences in the results of both analyses showed the inadequacy of the animal model approach for the evaluation of positional candidate genes in populations with linkage disequilibrium, when the probabilities of the parental origin of the QTL alleles are not included in the model.

OVilo C ，Oliver A ，Noguera JL ，Clop A ，Barragán C ，Varona L ，Rodríguez C ，Toro M ，Sánchez A ，Pérez-Enciso M ，Silió L ... -  《-》

The effect of adipocyte and heart fatty acid-binding protein genes on intramuscular fat and backfat content in Meishan crossbred pigs.

Effects of genetic variation in porcine adipocyte and heart fatty acid-binding protein genes, A-FABP and H-FABP, respectively, on intramuscular fat (IMF) content and backfat thickness (BFT) were examined in F2 crossbreds of Meishan and Western pigs. The involvement of each FABP gene in IMF accretion was studied to confirm previous results for Duroc pigs. The F2 crossbred pigs were genotyped for various markers including microsatellite sequences situated within both FABP genes. Linkage analysis assigned the A-FABP and H-FABP genes to marker intervals S0001-S0217 (20 cM) on SSC4 and Sw316-S0003 (16.6 cM) on SSC6, respectively, refining previous chromosomal assignments. Next, the role of both chromosome regions/genes on genetic variation in IMF content and BFT was studied by 1) screening SSC4 and SSC6 for QTL affecting both traits by performing a line-cross analysis and 2) estimation of the effect of individual A-FABP and H-FABP alleles on both traits. In the first analysis, suggestive and chromosome-wise significant evidence for a QTL affecting IMF was detected on SSC6. The H-FABP gene is a candidate gene for this effect because it resides within the large region containing this putative QTL. The second analysis showed a considerable but nonsignificant effect of H-FABP microsatellite alleles on IMF content. Suggestive evidence for a QTL affecting BFT was found on SSC6, but H-FABP was excluded as a candidate gene. In conclusion, present and previous results support involvement of H-FABP gene polymorphisms in IMF accretion independently from BFT in pigs. Therefore, implementation of these polymorphisms in marker-assisted selection to control IMF content independently from BFT may be considered. In contrast to previous findings for Duroc pigs, no evidence was found for an effect of the A-FABP gene on IMF or BFT in this population.

Gerbens F ，de Koning DJ ，Harders FL ，Meuwissen TH ，Janss LL ，Groenen MA ，Veerkamp JH ，Van Arendonk JA ，te Pas MF ... -  《JOURNAL OF ANIMAL SCIENCE》

Fine mapping of porcine chromosome 6 QTL and LEPR effects on body composition in multiple generations of an Iberian by Landrace intercross.

Ovilo C ，Fernández A ，Noguera JL ，Barragán C ，Letón R ，Rodríguez C ，Mercadé A ，Alves E ，Folch JM ，Varona L ，Toro M ... -  《Genetics Research》

Investigation of two candidate genes for meat quality traits in a quantitative trait locus region on SSC6: the porcine short heterodimer partner and heart fatty acid binding protein genes.

A highly significant quantitative trait locus (QTL) on pig chromosome 6, affecting intramuscular fat (IMF), has previously been detected by our group and others. Two genes of positional and biological interest, the small heterodimer partner (SHP; NR0B2) and the heart fatty acid binding protein (FABP3; H-FABP), were investigated for meat quality traits and IMF respectively. SHP was partially sequenced (GenBank: DQ002896 and DQ002897) and mapped to the QTL region on porcine chromosome 6, affecting IMF. The map shows no recombination between SHP and FABP3, which was previously mapped to the same QTL region. Twelve single nucleotide polymorphisms were detected in the sequenced region of SHP gene. Haplotype information was used to investigate association between genetic variation and different meat quality traits. SHP haplotype combinations were found to have significant effect on connective tissue. However, further studies are needed to evaluate this possible association more effectively. The FABP3 is involved in fatty acid transport and has been studied as a candidate gene for IMF by several research groups. In our study, FABP3 genotypes were confirmed to be significantly associated with IMF in pigs. The average content of IMF in our population was 1.6%, which may indicate that the FABP3 polymorphism explains as much as 30-35% of the variation in IMF in our pig cross-population.

Arnyasi M ，Grindflek E ，Jávor A ，Lien S ... -  《JOURNAL OF ANIMAL BREEDING AND GENETICS》

Investigation of porcine FABP3 and LEPR gene polymorphisms and mRNA expression for variation in intramuscular fat content.

Li X ，Kim SW ，Choi JS ，Lee YM ，Lee CK ，Choi BH ，Kim TH ，Choi YI ，Kim JJ ，Kim KS ... -  《-》