Generation and exploration of a dense genetic map in a region of a QTL affecting corpora lutea in a Meishan × Yorkshire cross

Abstract

Previously genomic scans revealed quantitative trait loci (QTL) on porcine Chromosome 8 (SSC8) as significantly affecting the number of corpora lutea (CL) in swine. In one study, statistical evidence for the putative QTL was found in the chromosomal region defined by the microsatellites (MS) SW205, SW444, SW206, and SW29. A Yeast Artificial Chromosome library was screened by using the corresponding primers for clones containing these MS by PCR. From five positive YAC clones, 10 additional MS were isolated and mapped to SSC8 with the INRA-University of Minnesota porcine Radiation Hybrid (IMpRH) panel. The genetic map position of the QTL has been refined by addition of these 10 markers. The QTL evaluation included pedigrees of F2-intercross Meishan x Yorkshire design, with phenotypic data of 108 F2 female offspring and genotypic data for 29 MS markers on SSC8. The analysis was performed by using the least squares regression method. The calculated QTL effect for CL obtained by the multilocus least squares method showed a maximum test statistic (F value = 13.98) at position 99 cM between three MS derived from YACs containing SW205 and SW1843 spanning an interval of 7.1 cM. The point-wise (nominal) P-value was 5.21 x 10-6 corresponding to a genome-wide P-value of 0.009. The additive QTL effect explained 17.4% of the phenotypic variance.

Mapping Quantitative Trait Loci Affecting Female Reproductive Traits on Porcine Chromosome 81

“…In a follow-up study, in which more markers were scored in these animals, the SSC8 centromeric QTL for number of corpora lutea was confirmed with increased confidence [21]. In the present study, a region was observed around the centromere of SSC8 that appeared to display an additive increasing effect from the Large White breed when GNRHR-2 genotypes were added as fixed effects to the QTL model.…”

“…Although earlier studies have provided evidence for QTL on this chromosome influencing several reproductive traits, none of these QTL has yet been confirmed across populations [6][7][8][19][20][21]. We report here, to our knowledge, the first independent confirmation of reproductive QTL on SSC8 and eliminate some candidate genes on the basis of their map locations.…”

“…Number of teats has not been investigated in most previous porcine reproductive QTL studies [6][7][8]21]. However, evidence for a QTL affecting number of teats also on the p arm of SSC8 at the genome-wide significance level (P Ͻ 0.05) has been reported [20].…”

QTL and candidate genes for fecundity in sows

“…Recent studies confirmed and narrowed these regions for the mapped QTL on SSC8. Braunschweig et al (2001) refined the genetic map by the use of 29 markers and confirmed the QTL at the centromere region of SSC8. Campbell et al (2003) narrowed the region at the telomeric end of the short arm on SSC8 using gene and microsatellite markers within the first 27 cM and confirmed and narrowed the QTL found by Rohrer et al (1999).…”

“…This gene is located at 8q11-q12 near the centromere where Wilkie et al (1999) and Braunschweig et al (2001) found a QTL for ovulation rate. A significant association between the C/G substitution in the 3 UTR and the number of corpora lutea at first parity was observed, so it can be assumed that GNRHR could have an effect on ovulation rate in pigs.…”