Pig Longissimus lumborum proteome: Part I. Effects of genetic background, rearing environment and gender A. Kwasiborski a , T. Sayd a , C. Chambon a , V. Santé-Lhoutellier a , D. Rocha b , C. Terlouw a, * a UR370 Qualité des Produits Animaux, INRA de Theix, F-63122 St. Genès Champanelle, France b Genus plc, Genus Cambridge Research Laboratory, Department of Pathology, University of Cambridge, CB2 1QP Cambridge, United Kingdom article info Article history: Received 5 October 2007 Received in revised form 14 February 2008 Accepted 28 April 2008 Keywords: Pig Proteome Meat quality Longissimus lumborum 2D-electrophoresis abstract A2  2  2 factorial experiment on Longissimus lumborum of 24 pigs found that rearing environment (indoors or outdoors), breed of sire (Duroc or Large White), and gender (female or castrated male) influ- enced 22, 10, and 88 proteins of the soluble fraction, respectively, containing 220 matched spots in total. Some proteins were influenced by more than one main effect. Outdoor rearing resulted in lower levels of enzymes of the glycolytic pathway suggesting a more oxidative metabolism. Breed of sire slightly altered the balance of enzymes of the glycolytic pathway. Gender had profound effects. In particular, different enzyme levels suggest a more lipid oriented energy metabolism, and a higher extractability of myofibr- illar proteins suggest altered control of the contractile apparatus, in castrated males. Differences in extractability did not explain the profound gender effects. Glycogen content, ultimate pH, drip and thaw- ing losses showed main or interactive effects of the three treatment factors. Ó 2008 Elsevier Ltd. All rights reserved. 1. Introduction Technological and sensory pork quality depends on genetic and rearing background of the pigs used (Bee, Guex, & Herzog, 2004; Enfält, Lundstrom, Hansson, Lundeheim, & Nystrom, 1997; Ter- louw & Rybarczyk, 2008). Oxidative and proteolytic processes in the post-mortem muscle determine to a large extent meat quality (Bendall, 1973; Rowe, Maddock, Lonergan, & Huff-Lonergan, 2004; Taylor et al., 1995). Proteins are central in these reactions as enzymes, but also as targets of oxidative and proteolytic activi- ties. It is likely that variations in protein levels mediate the effects of genetic and rearing background on meat quality. The objective of our work was to use proteomics to increase our understanding of the role of certain proteins or of the biochemical cellular events they mirror, in animal and environment-related influences on meat quality. Proteomic studies screen a chosen fraction of the cellular protein content at a given moment, generally containing several hundred proteins. Use of this technique has proven useful to iden- tify proteins that play a central role in meat quality. For example, they allowed to identification of proteins whose levels differed according to pork colour, drip loss or shear force (Hwang et al., 2004; Laville et al., 2007; Sayd et al., 2006). Such results may help to understand cellular mechanisms underlying variation in meat quality. The present paper reports the effects of genetic background, rearing environment and gender on protein levels in longissimus muscle samples obtained immediately after slaughter. The evalua- tion of relationships between protein levels and longissimus meat quality parameters will be reported in a separate paper (Kwasibor- ski et al., accepted for publication). The study uses the soluble cel- lular fraction that contains enzymes and regulators of protein expression. 2. Materials and methods 2.1. Animals, housing and slaughter Ten Large White  Landrace sows were inseminated with mixed semen from PIC Duroc and Large White sires. From about 100 piglets used for a larger study on behaviour, physiology and meat quality (Terlouw, Berne, & Astruc, submitted for publication), 48 have been selected, based on parenthood and weight. Pigs were born on the site in an outdoor farrowing system. They were weaned at 4 weeks and kept indoors until fattening at 2 months 0309-1740/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.meatsci.2008.04.028 Abbreviations: aParv, parvalbumin alpha; PPP, pyridoxal phosphate phospha- tase; HSP72, heat shock protein 72 kDa; GDI2, guanosine diphosphate dissociation inhibitor 2; ACYI, aminoacylase I; ALDH, aldehyde dehydrogenase; PKM1, pyruvate kinase isoform M1; b-ENO3, b-enolase 3; cG3PDH, cytosolic glycerol-3-phosphate dehydrogenase; CGI-29, CGI-29 protein; PRDX6, peroxiredoxin 6; TPI, triosephos- phate isomerase; PGAM1, phosphoglycerate mutase 1; MB, myoglobin; COF 2, cofilin 2. * Corresponding author. Present address: INRA de Theix, UR1213 Herbivores, F-63122 Saint-Genès Champanelle, France. Tel.: +33 (0) 473 62 45 69; fax: +33 (0) 473 62 41 18. E-mail address: Claudia.Terlouw@clermont.inra.fr (C. Terlouw). Meat Science 80 (2008) 968–981 Contents lists available at ScienceDirect Meat Science journal homepage: www.elsevier.com/locate/meatsci