The expression of genes PKM2 and CAST in the muscle tissue of pigs differentiated by glycolytic potential and drip loss, with reference to the genetic group H. Sieczkowska a, * , A. Zybert a , E. Krze ˛cio a , K. Antosik a , M. Koc ´ win-Podsiadła a , M. Pierzchała b , P. Urban ´ ski b a University of Podlasie, Chair of Pig Breeding and Meat Science, 14 Prusa Street, 08-110 Siedlce, Poland b Polish Academy of Science, Institute of Genetics and Animal Breeding, Jastrze ˛biec, 05-552 Wólka Kosowska, Poland article info Article history: Received 19 January 2009 Received in revised form 13 August 2009 Accepted 24 August 2009 Keywords: Pigs PKM CAST Gene expression Meat quality abstract The present studies aimed at an analysis of the expression level of genes PKM2 and CAST in Longissimus lumborum [LL] muscle tissue of pigs differing as regards the glycolytic potential [GP] and drip loss [DL] from the LL muscle, with reference to the genetic group. The studies covered a total of 65 pigs: 20 pure- bred Landrace [L], 22 crossbreeds of Landrace with the Yorkshire [L  Y] and 23 three-breed crosses (Landrace  Yorkshire)  Duroc [(L  Y)  D]. In the case of gene PKM2 one may observe in (L  Y)  D crossbreds, compared to L  Y crossbreds, an increased expression, closely related with the increase in dry matter content, including intramuscular fat, as well as a more favourable progress of glycolytic and energy metabolism during the early time post mortem (pH 45 and R 1 ). Compared with Landrace animals, the lower expression of the CAST gene observed in (L  Y)  D pigs is manifested by a marked improvement of meat quality (R 1 pH 45 pH 24 , pH 48 ), arising from the rate of glycolytic and energy metabolism, typical for normal meat, that in effect results in its higher culinary and technological value. Ó 2009 Elsevier Ltd. All rights reserved. 1. Introduction The process of glycogen breakdown to lactic acid is catalysed by a series of enzymes. One of them is pyruvate kinase, which cataly- ses the metabolism of phosphoenolpyruvate to pyruvate, that, in anaerobic conditions, is reduced to lactic acid (Fontanesi, Davoli, Nanni Costa, Scottio, & Russo, 2003; Pösö & Puolanne, 2005). Pyruvate kinase appears in four forms: M1, M2, L and R, of which forms M2 and M1 occur in muscles, heart and brain (Immamura, Noguchi, & Tanaka, 1986; Takegawa, Shinohara, & Miwa, 1984). Forms M1 and M2 are coded by gene PKM (Noguchi, Inoue, & Tanaka, 1986). Gene PKM2 (Pyruvate Kinase Muscle 2) was localised on chromosome 7 (7q12-q23) (Davoli et al., 2002). The relation between the polymorphism of gene PKM2 and glycogen content in Longissimus lumborum muscle at 45 min was reported by Fontanesi et al. (2003) and Sieczkowska et al. (2007). In turn, the calpastatin gene (CAST) is located on chromosome 2 within intron 6 (2q2.1–2q2.4) (Ernst, Robic, Yerle, Wang, & Rothschild, 1998). Calpastatin is an endogenous inhibitor of cal- pain, which in turn, depends in its proteolytic activity on the level of calcium. The activity of calpastatin is highly correlated with the muscle growth rate and the rate of proteolytic metabolism and meat tenderization post mortem (Goll, Thompson, Taylor, & Quali, 1998). The relation between the polymorphism of the calpastatin gene and qualitative and technological properties of pork are also important (Koc ´ win-Podsiadła et al., 2006; Koc ´ win-Podsiadła, Kurył, Krze ˛ cio, Zybert, & Przybylski, 2003). 2. Purpose of the research The present studies aimed at an analysis of the expression level of genes PKM2 and CAST in Longissimus lumborum [LL] muscle tissue of pigs differing as regards the glycolytic potential [GP] and drip loss [DL] from the LL muscle, with reference to the genetic group. 3. Materials and methods 3.1. Materials The studies covered a total of 65 pigs: 20 purebred Danish Landrace [L], 22 crossbreeds of Landrace with the Yorkshire [L  Y] and 23 three-breed crosses (Landrace  Yorkshire)  Duroc [(L  Y)  D]. The 65 pigs analysed were selected from a larger group (223 animals) on which meat quality measurements were made. Among each of genetic group the material was divided into four meat quality classes differentiated by glycolytic potential (GP 6 130 lmol/g and GP > 130 lmol/g) and drip loss (DL 6 6% and DL > 6%) of (LL) muscle tissue (Table 1). The expression of PKM2 and CAST genes was analysed for the chosen group of 65 pigs only. 0309-1740/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.meatsci.2009.08.038 * Corresponding author. Tel.: +48 256461257; fax: +48 256431258. E-mail address: kocwin@ap.siedlce.pl (H. Sieczkowska). Meat Science 84 (2010) 137–142 Contents lists available at ScienceDirect Meat Science journal homepage: www.elsevier.com/locate/meatsci