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For many species several similar QTL mapping populations have been produced and analyzed independently. Joint analysis of such data could be used to increase power to detect QTL and evaluate population differences. In this study, data were collated on almost 3000 pigs from seven different F(2) crosses between Western commercial breeds and either the European wild boar or the Chinese Meishan breed. Genotypes were available for 31 markers on chromosome 4 (on average 8.3 markers per population). Data from three traits common to all populations (birth weight, mean backfat depth at slaughter or end of test, and growth rate from birth to slaughter or end of test) were analyzed for individual populations and jointly. A QTL influencing birth weight was detected in one individual population and in the combined data, with no significant interaction of the QTL effect with population. A QTL affecting backfat that had a significantly greater effect in wild boar than in Meishan crosses was detected. Some evidence for a QTL affecting growth rate was detected in all populations, with no significant differences between populations. This study is the largest F(2) QTL analysis achieved in a livestock species and demonstrates the potential of joint analysis.

Mouse fibroblast interphase nuclei stained with quinacrine dihydrochloride show distinctive differences in their fluorescent characteristics analogous to those which we have already observed in human and Syrian hamster cells. These patterns reflect the position of any given nucleus within the cell cycle. The brightly fluorescent chromocenters in the mouse nuclei were found to be in absolute aggreement with those stained by the C-banding technique, indicating that they represent centromeric heterochromatin. Furthermore, their number and size per nucleus were shown to vary in relation to the progress of the cell cycle.

Linkage and QTL maps of Sus scrofa chromosome 11 (SSC11) have been produced based on four microsatellite markers genotyped in three F2 families from Wild Boar (W), Meishan (M) and Pietrain (P) crosses. The maps were similar across the families and in agreement with already published maps. Quantitative Trait Loci (QTLs) were identified in the W x M family and not in the M × P and W × P families. The QTLs affected live weight, loin and neck meat weight, back-fat depth and food consumption, and explained up to 4.7% of the F2 phenotypic variance. Additive and dominance effects were similar in size. The Wild Boar QTL alleles led to higher trait values in comparison with Meishan alleles. [ABSTRACT FROM AUTHOR]

Linkage maps of Sus scrofa chromosome 8 (SSC8) were constructed using seven markers in three F2 families based on Meishan (M), Pietrain (P) and Wild Boar (W) crosses. The maps were similar for the pedigrees and in agreement with published maps. Most quantitative trait loci (QTLs) were found for the W × P family, while only minor QTLs were detected in the M × P and W × M families. SSC8 harbours QTLs mapped in the interval SW905 to SW933 explaining up to 6% of the F2 phenotypic variance for body conformation, carcass and growth traits. Pietrain alleles positively influenced carcass traits, with additive effects often larger than dominance effects. For food conversion ratio a large dominance QTL effect was observed in the M × P family. [ABSTRACT FROM AUTHOR]

Linkage and QTL maps of Sus scrofa chromosome 17 (SSC17) were analysed with five markers and in three F2 families basedon Wild Boar (W), Meishan (M) and Pietrain (P) crosses. The maps were similar across the three families and agree well with published maps. In the M × P family, new quantitative trait loci (QTLs) for growth and fat deposition were locatedin the vicinity of GHRH, whereas in the W × P family one minor QTLs for daily gain was detected. No QTL was found in the W x M family. [ABSTRACT FROM AUTHOR]

The Sus scrofa chromosome 15 (SSC15) linkage maps were produced with six markers in three F2 families based on Wild Boar (W), Meishan (M) and Pietrain (P) crosses. The maps were similar for the different families, with a higher rate of maternal recombination than paternal only in the M x P family. Quantitative trait loci (QTLs) for carcass composition (dressing yield, lean cuts and fat depth) explained up to 9% of F2 phenotypic variance in the W × P family and mapped near the marker S0148 (0 cM). Similar QTLs for fat depth were observed in the W × M family, where a minor QTL for dressing yield was mapped in the interval EAG-SW964 (approximately at 25 cM). No SSC15 QTL was found in the M × P family. [ABSTRACT FROM AUTHOR]

The SSC12 (Sus scrofa chromosome 12) linkage and QTL maps were generated using 11 markers, of which seven to 10 have been used in the three F2 families based on Wild Boar (W), Meishan (M) and Pietrain (P) crosses. Linkage maps showed identical marker order among the families, but differed in total lengths. They were in agreement with the already published maps, except for the order SWR1021SW605. Most quantitative trait loci (QTLs) affected fat or meat content in carcass, but were also found for some other traits (heart weight, CK20 values and teat number). They explained up to 5.4% of F2 phenotypic variance. Meishan alleles had stimulating effects on fat deposition and decreasing effects on lean content and CK20 value. The QTL profiles differed between families, with QTL effects in the vicinity of the GH1 locus found solely in the M x P family. [ABSTRACT FROM AUTHOR]

Linkage and QTL maps of Sus scrofa chromosome 9 (SSC9) were constructed using 16 markers, with 13 to 15 used in three F2 families based on Wild Boar (W), Meishan (M) and Pietrain (P) crosses. The LPR and SLN loci were integrated into the linkage map of SSC9 for the first time. Only a few quantitative trait loci (QTLs), explaining up to 5.1% of the F2 phenotypic variance, were identified on SSC9 with chromosome-wide significant effects on growth and fattening in the W x P family and on weight of liver, growth and fat-to-meat ratio in the W x M family. No QTLs were found in the M x P family. Gene effects were mainly dominant in the W x P family. In the W × M family, Wild Boar QTL alleles for weight of liver were superior over Meishan alleles. [ABSTRACT FROM AUTHOR]

Linkage maps have been constructed for Sus scrofa chromosome 6 (SSC6) based on 17 markers, of which 10 were used in all three F2 families of Wild Boar (W), Meishan (M) and Pietrain (P) crosses. The coverage of the linkage maps of SSC6 was almost complete. All loci were ordered identically in the families, but two intervals (RYR1-A1BG-EAH, S0146-S0003-SW824) differed from published maps. Major quantitative trait loci (QTLs) for meat quality, stress resistance and carcass composition explaining up to 59% of F2 phenotypic variance have been mapped in the M x P and W x P families centred on the segregating R YR1 T and C alleles. In the W × M family, which was homozygous for the RYR1 C allele, no QTL effects for meat quality and stress-resistance, but moderate effects for carcass composition have been observed in this region. These findings indicate further loci closely linked with the RYR1 or/and further alleles at the RYR1 locus, involved in the variation of carcass and growth traits. [ABSTRACT FROM AUTHOR]

Linkage maps of Sus scrofa chromosome 7 (SSC7) for three informative F2 families, based on Wild Boar (W), Meishan (M) and Pietrain (P) crosses, were constructed using 16 marker loci. Maps were consistent for the families, except the order of the markers PI2-PO1A-S0212 in the W × M family which was inverted in the M x P and W x P families. Important quantitative trait loci (QTLs) were localized in the region of the SLA complex in the M x P and W × M families. These explained up to 16% of F2 phenotypic variance for body conformation, fat deposition and muscling. In the W × P family, minor QTLs were mapped outside the SLA region. The highly significant QTL alleles were mainly additive (a > d). The Meishan alleles for QTL located in the SLA region were associated with higher head weights and carcass lengths, but with lower carcass fat contents than those from Wild Boar and Pietrain. The cryptic Meishan QTL allele, which reduces carcass fat, provides one of the first examples of transgressive segregation in animals and emphasizes that usefulgenetic variation can be hidden in the genetic background of a breed. [ABSTRACT FROM AUTHOR]

Sus scrofa chromosome 2 (SSC2) linkage maps were generated from three F2 families involving Meishan (M), Pietrain (P) and Wild Boar (W) crosses and the same 10 marker loci. SSC2 linkage maps were similar between families and correspond to published maps. Quantitative trait loci (QTLs) for carcass traits, daily gain and heart weight were identified on SSC2, especially in the intervals 0-20 and 80-90 cM in the M × P family, the intervals 20-50 and 125-140 cM in the W × P family, and the interval 15-70 cM in the W × M family. QTL presence and position varied among families. QTL effects explained up to 10% of F2 phenotypic variance. Pietrain QTL alleles were associated with high muscle and heart mass, high daily gain and low fat deposition and Meishan alleles with high carcass fat content. Wild Boar alleles were associated with leaner carcass but lower daily gain than Meishan alleles. [ABSTRACT FROM AUTHOR]

Linkage maps of Sus scrofa chromosome 5 (SSC5) were constructed using up to 10 markers in three informative F2 families based on Wild Boar (W), Meishan (M) and Pietrain (P) crosses. The map lengths differed among the families. In the M × P family, the MYF5 locus was linkage mapped between SW995 and SW967. Relatively few quantitative trait loci (QTLs) were observed on SSC5 explaining a maximum of 5.8% of phenotypic variance in the F2 generation. The presence and position of QTLs were not consistent among families. The Meishan and Wild Boar QTL allele effects were inferior compared with Pietrain allele effects. The additive effects were small and reasonably strong dominance-effects were observed. QTLs affecting conductivity in the W × M family and food conversion ratio in the M x P family mapped near MYF5, while the QTL affecting conductivity in the M x P family was located near IGF1. [ABSTRACT FROM AUTHOR]

Linkage maps of Sus scrofa chromosome 3 (SSC3) were established on the basis of eight marker loci using three F2 families generated from crosses of Meishan (M), Pietrain (P) and Wild Boar (W) founders. The maps were similar for the three families and in agreement with the published linkage maps. Recombination was significantly higher in maternal than in paternal meioses. Quantitative trait loci (QTLs), explaining up to 6.0% of the F2 phenotypic variance, were mapped for daily gain, carcass traits and meat quality in proximal and central intervals of SSC3. The QTLs detected were often family-specific. Pietrain QTL alleles were superior for muscle traits in comparison with Meishan alleles, and Wild Boar QTL alleles caused lower values for fatness than Pietrain alleles. [ABSTRACT FROM AUTHOR]

Linkage maps of Sus scrofa chromosome 4 (SSC4) based on 19 markers were similar in lengths for three F2-families [Wild Boar (W), Meishan (M) and Pietrain (P) crosses] and in agreement with the previously published maps. Quantitative trait loci (QTLs) on SSC4 affect mainly muscle and fat mass. Compared with others, Pietrain alleles were associated with longer carcass, higher body weight and higher meat content. In all three families, the profiles of F ratio values for these traits showed peaks close to the positions of candidate genes V-ATPase, ATP1A2 and ATP1B1. Additional more proximally mapped QTLs, significant at the p < 0.05 chromosome-wide level, were found in the M x P and W x P families. The W × M family revealed highly significant QTLs located in the vicinity of AMPD1 and NGFB. The SSC4 QTLs explained up to 12% of F2 phenotypic variance. [ABSTRACT FROM AUTHOR]

Linkage maps of Sus scrofa chromosome 1 (SSC1) have been produced using 10 markers in three different F2 families based on crosses of Meishan (M), Pietrain (P) and Wild Boar (W). The maps were similar for the different families and show higher paternal recombination, especially in the interval SW2130-SW803. Quantitative trait loci (QTLs) affecting body conformation, carcass composition, fat deposition and numbers of teats were identified in all three families. Major QTLs were mapped in chromosomal intervals centred at approximately 60, 120 and 170 cM. The QTLs explain up to 8.4% of phenotypic variance in the F2 generation. Pietrain QTL alleles were superior in comparison with Wild Boar andMeishan alleles for most of the trait values. Meishan alleles were associated with highest fat deposition. Additive gene effects were generally larger than dominance effects. QTL profiles on SSC1 differed between families, with the W x P family being most distinct. [ABSTRACT FROM AUTHOR]