E.J. Squires
Professor
Biochemistry and Molecular Biology
B.Sc., M.Sc., Ph.D. Memorial
email: jsquires@uoguelph.ca
Research Areas
My broad research interests are in metabolism and functional genomics. Of particular interest is the metabolism of boar taint compounds and factors that affect their production and catabolism. My lab has identified some of the key enzymes involved in the metabolic pathways for skatole and androstenone. We are characterizing the substrate and inhibitor specificity of a number of porcine CYP450s and phase II enzymes, and are studying the role of nuclear receptors CAR, PXR and FXR in the pig, including their ligand specificity, the role of splice variants, and the downstream effects of receptor activation. My lab has identified a number of polymorphisms in candidate genes that code for key enzymes involved in the metabolism of boar taint compounds. We are particularly interested in polymorphisms that affect the function of these enzymes and thus dramatically affect the trait, and are developing a SNP panel that will be used for genetic selection for low boar taint lines of pigs. We are also working with collaborators to develop panels of genetic markers for other desirable traits, including improved disease resistance and increased productivity (feed efficiency, growth performance, and meat quality). We are also working with collaborators on hemostasis and metabolic diseases in poultry. Based on the similarities in phase I and II metabolism and nuclear receptor function between pigs and humans, we are developing a porcine hepatocyte model for toxicology and metabolic disease studies relevant to humans.
Selected Publications
- Squires, E.J. Applied Animal Endocrinology. 2nd Ed. Modular Texts Series. CABI Bookshop. November 2010.
- Leung, M.C.K., K.-L. Bowley and E.J. Squires. 2010. Examination of testicular gene expression patterns in Yorkshire pigs with high and low levels of boar taint. Anim. Biotech. (in press)
- Gray, M.A, J.N. Peacock and E.J. Squires. 2009. Characterization of the porcine Constitutive Androstane Receptor (CAR) and its splice variants. Xenobiotica 39:915-930.
- Billen, M. and E.J. Squires. 2009. The role of porcine cytochrome b5A and cytochrome b5B in the regulation of cytochrome P45017A1 activities. J. Steroid Biochem. Mol. Biol. 113:98–104.
- Yeh, E., R.D. Wood, S. Leeson and E.J. Squires. 2008. Effect of dietary omega-3 and omega-6 fatty acids on clotting activities of Factors V, VII and X in fatty liver haemorrhagic syndrome-susceptible laying hens. Br. Poultry Sci. 50:382-392.
- Yeh, E., R.D. Wood and E.J. Squires. 2008. Influence of plasma lipid composition on activity of Factors V, VII and X in Single Comb White Leghorn and fatty liver haemorrhagic syndrome-susceptible laying hens. Br. Poultry Sci. 49:760-769.
- Zamaratskaia, G. and E.J. Squires. 2008. Biochemical, nutritional and genetic effects on boar taint in entire male pigs. Animal: An International Journal of Animal Bioscience 3:1508-1521.
- Peacock J., Y. Lou, K. Lundström and E.J. Squires. 2007. The effect of a c.-8G>T polymorphism on the expression of cytochrome b5A and boar taint in pigs. Anim. Genet. 39:15-21.
- Lanthier, F., Y. Lou and E.J. Squires. 2007. Skatole metabolism in the intact pre-pubescent male pig: the relationship between hepatic enzyme activity and skatole concentrations in plasma and fat. Livest. Sci. 106:145-153.
- Lillie, B.N., N.D. Keirstead, E.J. Squires and M.A. Hayes. 2007. Gene polymorphisms associated with reduced hepatic expression of porcine mannan-binding lectin C. Dev. Comp. Immunol. 31:830-846.
- Zamaratskaia, G., W.J. Gilmore, K. Lundstrom and E.J. Squires. 2007. Effect of testicular steroids on catalytic activities of cytochrome P450 enzymes in porcine liver microsomes. Food Chem. Toxicol. 45(4):676-681.
- Zamaratskaia, G., Y. Lou, J. Peacock, L. Rydhmer, H.K. Andersson, R.K. Juneja, G. Chen., K. Lundstrom and E.J. Squires. 2007. Effect of polymorphism in the porcine cytochrome b5 (CYB5A) gene on androstenone and skatole concentrations and sexual development in Swedish swine populations. Animal 2(2):190-196.
- Zamaratskaia, G., Y. Lou, G. Chen, K. Lundstrom, O. Andresen and E.J. Squires. 2007. Effect of hCG stimulation on plasma androstenone concentrations and cytochrome b5 levels in testicular tissue. Reprod. Dom. Anim. 42:105-108.
- Lin, Z., Y. Lou and E.J. Squires. 2006. Functional polymorphism in porcine CYP2E1 gene: its association with skatole levels J. Steroid Biochem. Mol. Biol. 99:231-237.
- Lanthier, F., Y. Lou, M.A. Terner and E.J. Squires. 2006. Characterizing developmental changes in plasma and tissue skatole concentrations in the pre-pubescent intact male pig. J. Anim. Sci. 84:1699-1708.
- Terner, M.A., W.J. Gilmore, Y. Lou and E.J. Squires. 2006. The role of CYP2A and CYP2E1 in the metabolism of 3-methylindole in primary cultured porcine hepatocytes. Drug Metabolism and Disposition 34:848–854.
- Sinclair, P.A., W.J. Gilmore, Z. Lin, Y. Lou and E.J. Squires. 2006. Molecular cloning and regulation of porcine SULT2A1: Relationship between SULT2A1 expression and sulfoconjugation of androstenone. J. Mol. Endocrinol. 36:301–311.
- Lillie, B.N., N.D. Keirstead, E.J. Squires and M.A. Hayes. 2006. Single nucleotide polymorphisms in porcine mannan-binding lectin A. Immunogenetics 58(12):983-993.
- Zamaratskaia, G., E.J. Squires, J. Babol, H.K. Andersson, K. Andersson and K. Lundström. 2005. Relationship between the activities of cytochromes P4502E1 and P4502A6 and skatole content in fat in entire male pigs fed with and without raw potato starch. Livest. Prod. Sci. 95:83-88.
- Sinclair, P.A., S. Hancock and E.J. Squires. 2005. Metabolism of the 16-androstene steroids in primary porcine hepatocytes. J. Steroid Biochem. Mol. Biol. 96:79-87.
- Sinclair, P.A. and E.J. Squires. 2005. Testicular sulfoconjugation of the 16-androstene steroids by hydroxysteroid sulfotransferase: its impact on the concentrations of 5α-androstenone in plasma and fat of the mature domestic boar. J. Anim. Sci. 83:359-365.
- Lin, Z., Y. Lou and E.J. Squires. 2005. Identification of a single nucleotide polymorphism in porcine testis cytochrome P450-C17 (CYP17) and its effect on steroidogenesis. Biochem. Genet. 43:531-542.
- Stewart, J.D., Y. Lou, E.J. Squires and P.M. Coussens. 2005. Using human microarrays to identify differentially expressed genes associated with increased steroidogenesis in boars. Anim. Biotech. 16:139-151.
- Lin Z.H., Y.P. Lou, J. Peacock and E.J. Squires. 2005. A novel polymorphism in the 5 ' untranslated region of the porcine cytochrome b5 (CYB5) gene is associated with decreased fat androstenone level. Mamm. Genome 16(5):367-373.
- Sinclair, P.A., J.I. Raeside, R. Renaud and E.J. Squires. 2005. Synthesis of free and sulfoconjugated 16-androstene steroids by the leydig cells of the mature domestic boar. J. Steroid Biochem. Mol. Biol. 96:217-228.
- Zamaratskaia, G., J. Babol, A. Madej, E.J. Squires and K. Lundström. 2005. Free oestrone in adipose tissue and its relation to androstenone and skatole in entire male pigs. Reprod. Dom. Anim. 40(2):156-160.
Teaching
- ANSC*4350
Experiments in Animal Biology
This course provides an opportunity for hands-on projects involving live animals and laboratory techniques. Projects will be provided by Animal & Poultry Science faculty within their broad fields of study, for example animal behaviour and welfare, environmental physiology, endocrinology, and reproduction.
- ANSC*4490
Applied Endocrinology
This course examines the endocrine systems of farm animals and their applications to livestock production. Considerable emphasis will be placed upon understanding how knowledge of endocrine regulation can be applied within animal production systems. TEXTBOOK - Applied Animal Endocrinology (2nd Edition) by E.J. Squires
Experience and Training
Postdoctoral Fellow Assistant Professor Associate Professor Professor
B.Sc. (Hons) M.Sc. Ph.D.