The effect of a c.‐8G>T polymorphism on the expression of cytochrome b5A and boar taint in pigs

Abstract

The level of cytochrome b5A (CYB5A) in pig testis is correlated with boar taint from androstenone and an AF016388:c.-8G>T polymorphism in CYB5A has been linked with low androstenone levels in the fat of pigs. In this study, we developed a polymerase chain reaction-based assay to genotype 1242 boars from eight lines for the c.-8G>T SNP. The c.-8T allele was found in all eight lines at a frequency ranging from 1.8% to 20.3% with an overall frequency of 8.6%. Significant deviations from Hardy-Weinberg equilibrium were found in the Hampshire, Landrace and Yorkshire breeds. The homozygous mutant c.-8TT occurred infrequently and was not found in some lines, but was consistently associated with low androstenone levels in fat. Both CYB5A mRNA and CYB5A protein levels were decreased in the c.-8TT genotype in a subset of Yorkshire boars, suggesting that low levels of CYB5A protein in the c.-8TT mutant were not due to inefficient translation of CYB5A mRNA. There were significant but modest marker effects on fat androstenone levels in Landrace, Yorkshire and a Large White/Duroc cross and fat skatole in Duroc and Sire Line breeds. There was no effect of CYB5A genotype on bulbourethral gland length, suggesting that this SNP will not affect reproductive traits. We conclude that the c.-8G>T SNP in the CYB5A gene has a significant but modest effect on boar taint in male pigs and could be useful in some breeds as part of a panel of SNP markers in a marker-assisted selection programme to produce low boar taint pigs.

Effect of polymorphism in the porcine cytochrome b5 (CYB5A) gene on androstenone and skatole concentrations and sexual development in Swedish pig populations

“…A statistical analysis showed that androstenone levels were lower in plasma in the G/T genotype at 90 kg live weight, and skatole levels were lower in plasma and fat Zamaratskaia, Lou, Peacock, Rydhmer, Andersson, Juneja, Chen, Lundströ m and Squires in the G/T genotype at 115 kg live weight. Lower androstenone and skatole levels in fat from the pigs with the T allele compared with those in the pigs with the G allele in some breeds were also observed by Peacock et al (2007). Our study suggests that skatole levels might be affected by polymorphisms in the CYB5A gene.…”

“…It is unclear as to why the polymorphism in gene CYB5A in the present study affects androstenone levels in plasma, but not in fat. In contrast, Lin et al (2005) and Peacock et al (2007) observed the effect of CYB5A genotype on fat androstenone levels. On the other hand, within breed analysis demonstrated that this effect was significant only in some breeds (Peacock et al, 2007).…”

“…Liver and blood samples were processed according to the manufacturer's instruction for mammalian tissues. DNA was further used for analysis of genetic polymorphisms by PCR amplification as described by Peacock et al (2007). Briefly, 1 ml of genomic DNA was amplified for 31 cycles using three primers; B5-control-F (5 0 -TAT TAC ACC CTG GAA GAG GAT-3 0 ), B5-exon1-R (5 0 -TAC ACT TTG TGG TGC AGG ATT AG-3 0 ) and B5-mutant-F (5 0 -GCC TGA GGT TCG CCG CT-3 0 ).…”

Influence of breed and slaughter weight on boar taint prevalence in entire male pigs

“…Literature describes a positive correlation between the DG and measured androstenone levels (Weiler et al, 1995) and a negative correlation between the lean meat percentage, the yield of valuable joints and boar taint levels (Andersson et al, 1999;Walstra et al, 1999;Hortos et al, 2000). P has previously been reported to display lower androstenone levels as compared with LW and Landrace (Peacock et al, 2008), and lower skatole levels as compared with LW 3 P .…”

The roles of different porcine cytochrome P450 enzymes and cytochrome b5A in skatole metabolism

“…The ability of CYB5A to modify the activity of CYP17A1 in the pig has been reported (Billen and Squires, 2009), and a c.-8G.T polymorphism in the CYB5A gene was associated with low androstenone levels in fat and low levels of both CYB5A mRNA and CYB5A protein (Peacock et al, 2008). The contribution of CYB5A to CYP450-mediated catalysis is complex and is dependent on the substrate and CYP450 isoform (Schenkman and Jansson, 2003).…”