A novel polymorphism in the 5′ untranslated region of theporcine cytochrome b5 (CYB5) gene is associated with decreased fat androstenone level

Abstract

Raising intact male pigs would have a significant economic impact on the pork industry; however, the presence of 16-androstene (a major cause of boar taint) in meat from male pigs would be highly objectionable to consumers. In pigs, a positive correlation has been found between cytochrome b5 (CYB5) and production of 16-androstene. The search for polymorphism of CYB5 and functional analysis of polymorphism found should have an important impact on the efforts to develop genetic markers to select for low androstenone levels in fat from pigs. The aim of this study was to search the porcine CYB5 gene for mutations, examine its expression, identify genetic polymorphisms, and study how a genetic variation in this enzyme translates into interindividual variation in androstenone levels in fat from pig testis. We have identified a single nucleotide polymorphism (SNP) (G --> T) at base 8 up-stream of ATG in the CYB5 5' untranslated region which is associated with a lower fat androstenone level. Of the 229 testis samples tested, 84.8% were homozygous for the variant G, 12.4% were heterozygous, and 2.8% were homozygous for the variant T. Functional analysis of this mutation revealed that an individual homozygous for the T allele showed significantly lower CYB5 activity than an individual homozygous for the G allele. Thus, this may be at least partially responsible for a lower level of androstenone in pigs. Our findings provide an important genetic basis toward the goal of predicting the androstenone status in pigs and developing genetic markers for low androstenone.

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

“…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).…”

“…CYB5 is an important regulator of 17,20-lyase activity of P450C17, the enzyme essential for steroidogenesis (Pandey and Miller, 2005) and particularly for androstenone biosynthesis (Meadus et al, 1993). Genetic polymorphisms in the porcine gene coding for CYB5A result in different phenotypes with respect to the ability to express boar taint due to androstenone (Lin et al, 2005). In the present study, the effect of this polymorphism on the levels of boar taint and sexual development in Swedish pig populations has been investigated.…”

“…Several genomic regions were demonstrated to harbour quantitative trait loci for the variation of androstenone levels in fat (Quintanilla et al, 2003). Recently, Lin et al (2005) have demonstrated a strong association of a single-nucleotide G . T polymorphism at base 28 upstream of ATG in the CYB5A 5 0 untranslated region with lower androstenone levels for the G/T and T/T genotypes.…”

Genetic and metabolic aspects of androstenone and skatole deposition in pig adipose tissue: A review(Open Access publication)

“…I) and a SNP at base 8 upstream of the ATG in the CYB5 5'UTR has been identified [24]. This SNP is associated with a significant decrease in CYB5 protein expression (in vitro demonstration) and a low level of androstenone in the fat of animals from a variety of European breeds [24]. The putative location of CYB5 in the porcine genome (Tab.…”

Biochemical, nutritional and genetic effects on boar taint in entire male pigs

“…However, only a few studies have reported SNPs in these genes that are correlated with levels of boar taint. These include an SNP in the CYP2E1 promoter (Skinner et al, 2005), an SNP in the coding region of CYP2E1 (Skinner et al, 2005;Lin et al, 2006), a single base deletion in the coding region of CYP2A (Lin et al, 2004a), and an SNP in the coding region of SULT1A1, which may all be related to skatole deposition (Lin et al, 2004b), and an SNP in the 5 0 untranslated region of CYB5 related to decreased androstenone synthesis (Lin et al, 2005). The importance of some of these markers was not supported by other studies (Skinner et al, 2006), and this may be due to the small number of animals or differences in the breeds used in these studies.…”