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 upstream 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.
Similar content being viewed by others
References
Babol J, Squires EJ, Lundstrom K (1998) Relationship between oxidation and conjugation metabolism of skatole in pig liver and concentrations of skatole in fat. J Anim Sci 76, 829–838
Bonneau M, Meadus WJ, Squires EJ (1992) Effects of exogenous porcine somatotropin on performance, testicular steroid production and fat levels of boar-taint-related compounds in young boars. Can J Anim Sci 72, 537–545
Cristiano RJ, Steggles AW (1989) The complete nucleotide sequence of bovine liver cytochrome b5 mRNA. Nucleic Acids Res 17, 799
Davis SM, Squires EJ (1999) Association of cytochrome b5 with 16-androstene steroid synthesis in the testis and accumulation in the fat of male pigs. J Anim Sci 77, 1230–1235
Giordano SJ, Kaftory A, Steggles AW (1994) A splicing mutation in the cytochrome b5 gene from a patient with congenital methemoglobinemia and pseudohermaphrodism. Hum Genet 93, 568–570
Giordano SJ, Yoo M, Ward DC, Bhatt M, Overhauser J, et al. (1993) The human cytochrome b5 gene and two of its pseudogenes are located on chromosomes 18q23: 14q31-32.1 and 20p11.2, respectively. Hum Genet 92, 615–618
Katkov T, Gower DB (1970) The biosynthesis of androst-16-enes in boar testis tissue. Biochem J 117, 533–538
Keyes SR, Cinti DL (1980) Biochemical properties of cytochrome b5-dependent microsomal fatty acid elongation and identification of products. J Biol Chem 255, 11357–11364
Kozutsumi Y, Kawano T, Kawasaki H, Suzuki K, Yamakawa T, et al. (1991) Reconstitution of CMP-N-acetylneuraminic acid hydroxylation activity using a mouse liver cytosol fraction and soluble cytochrome b5 purified from horse erythrocytes. J Biochem (Tokyo) 110, 429–435
Lin Z, Lou YP, Squires JE (2004a) Molecular cloning and functional analysis of porcine SULT1A1 gene and its variant: a single mutation SULT1A1 causes a significant decrease in sulfation activity. Mamm Genome 15, 218–232
Lin ZH, Lou YP, Squires EJ (2004b) Molecular cloning, expression and functional characterization of the cytochrome P450 2A6 gene in pig liver. Anim Genetics 35, 314–316
Meadus WJ, Mason JI, Squires EJ (1993) Cytochrome P450c17 from porcine and bovine adrenal catalyses the formation of 5,16-androstadien-3 beta-ol from pregnenolone in the presence of cytochrome b5. J Steroid Biochem Mol Biol 46, 562–572
Ogishima T, Kinoshita JY, Mitani F, Suematsu M, Ito A (2003) Identification of outer mitochondrial membrane cytochrome b5 as a modulator for androgen synthesis in Leydig cells. J Biol Chem 278, 21204–21211
Ozols J (1989) Structure of cytochrome b5 and its topology in the microsomal membrane. Biochim Biophys Acta 997, 121–130
Quintanilla R, Demeure O, Bidanel JP, Milan D, Iannuccelli N, et al. (2003) Detection of quantitative trait loci for fat androstenone levels in pigs. J Anim Sci 81, 385–394
Schenkman JB, Jansson I (2003) The many roles of cytochrome b5. Pharmacol Ther 97, 139–152
Squires EJ, Lundstrom K (1997) Relationship between cytochrome P450IIE1 in liver and levels of skatole and its metabolites in intact male pigs. J Anim Sci 75, 2506–2511
Strausberg RL, Feingold EA, Grouse LH, Derge JG, Klausner RD, et al. (2002) Generation and initial analysis of more than 15,000 full-length human and mouse cDNA sequences. Proc Natl Acad Sci USA 99, 16899–16903
Takeshita M, Tamura M, Yoshida S, Yubisui T (1985) Palmitoyl-CoA elongation in brain microsomes: dependence on cytochrome b5 and NADH-cytochrome b5 reductase. J Neurochem 45, 1390–1395
VanDerMark PK, Steggles AW (1997) The isolation and characterization of the soluble and membrane-bound porcine cytochrome b5 cDNAs. Biochem Biophys Res Commun 240, 80–83
Xue J, Dial GD, Holton EE, Vickers Z, Squires EJ, et al. (1996) Breed differences in boar taint: relationship between tissue levels boar taint compounds and sensory analysis of taint. J Anim Sci 74, 2170–2177
Acknowledgments
Funding from Natural Sciences and Engineering Research Council of Canada (NSERC) and Ontario Ministry of Agriculture and Food, Canada supported this study.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Lin, Z., Lou, Y., Peacock, J. et al. A novel polymorphism in the 5′ untranslated region of theporcine cytochrome b5 (CYB5) gene is associated with decreased fat androstenone level. Mamm Genome 16, 367–373 (2005). https://doi.org/10.1007/s00335-004-2439-4
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/s00335-004-2439-4