Jolanta Kurył

Polymorphisms in coding and regulatory regions of the porcineMYF6 andMYOG genes and expression of theMYF6 gene inm. longissimus dorsi versus productive traits in pigs

MYOG andMYF6 belong to theMyoD gene family. They code for the bHLH transcription factors playing a key role in later stages of myogenesis: differentiation and maturation of myotubes. Three SNPs in porcineMYF6 and two in porcineMYOG were analysed in order to establish associations with chosen carcass quality and growth rate traits in Polish Landrace, Polish Large White and line 990 sows. No statistically significant effect of SNP in the promoter region of theMYF6 gene on its expression measured on mRNA level was found. Associations between the genotype at theMYF6 locus and carcass quality traits appeared to be breed-dependent. The C allele in the case of SNP in the promoter region and GC haplotype in exon 1 were advantageous for right carcass side weight in Polish Landrace sows and disadvantageous for this trait in Polish Large White sows. These gene variants were also the most advantageous for loin and ham weight in sows of line 990. The mutation in exon 1 of theMYOG gene had no statistically significant association with carcass quality traits and the mutation in the 3’-flanking region had the breed-dependent effect as well. These results suggest that SNPs analysed in this study are not causative mutations, but can be considered as markers of some other, still unrevealed genetic polymorphism that influences the physiological processes and phenotypic traits considered in this study.

Muscle glycogen level and meat quality in pigs of different halothane genotypes

The halothane genotype of 22 Polish landrace pigs was determined using halothane test and blood typing. Eight homozygous normal (NN), eight hetero-zygotes (Nn) and six homozygous recessive (nn) were identified. The levels of glycogen and lactate were measured in biopsy samples taken from the longissimus lumborum using a shot biopsy technique. pH (pH(1)) and IMP/ATP ratio (R) were determined at 30 min after slaughter, while pH, meat colour and water holding capacity were determined on the day after slaughter. The halothane genotype did not affect intra vitam glycogen level. The nn pigs had a higher R value and lower pH(1) than both Nn and NN animals. Heterozygous animals were intermediate between both homo-zygotes for biopsy lactate level and meat colour. The lactate content of biopsy samples was significantly correlated with pH(1) (r = -0·68; P < 0·01), R (r = 0·68; P < 0·01), meat colour (r = 0·57; P < 0·01) and water holding capacity (r = 0·45; P · 0·05).

The effect of interaction between genotype CAST/RsaI (calpastatin) and MYOG/MspI (myogenin) on carcass and meat quality in pigs free of RYR1T allele

The purpose of the studies was to demonstrate to what degree genotypes of calpastatin (CAST/RsaI) and myogenin (MYOG) genes as well as the interaction between them may affect the carcass and meat quality of pigs. The investigations were conducted on 397 stress resistant pigs (free of RYR1(T) allele). It was demonstrated that the favourable effect of the variants of CAST and MYOG genes on carcass quality traits depends on the cut. The gene variant favourably affecting the weight of ham simultaneously had a negative effect on the weight of the loin. It was also shown that the interaction between CAST and MYOG genotypes has a significant effect on backfat thickness. The effect of a given combination of CAST and MYOG genotypes on carcass traits is related to the weight of a substantial cut (ham, loin). Genotypes at loci CAST/RsaI and MYOG have a significant effect on the value of certain traits and parameters of meat quality and its technological value (genotype CAST on pH at 35min and 2, 3, 24, 48, 96, 144h post-mortem (pH(35), pH(2), pH(3), pH(24), pH(48), pH(96), pH(144), respectively), R(1) (IMP/ATP), electrical conductivity at 3 and 4h post-mortem (EC(3), EC(4)), technological yield of meat in curing and thermal processing (TY) and protein content in the muscle tissue, while genotype MYOG on pH(48), EC(35), EC(3), EC(24) and dry matter content).

Polymorphism in Coding and Non-coding Regions of the MyoD Gene Family and Meat Quality in Pigs*

The aim of the study was to evaluate the relations between genotype effects at porcine loci MYF3, MYF4, MYF5 and MYF6 on meat quality traits in pigs of the CC genotype at the RYR1 locus. Meat traits were analysed in longissimus lumborum muscle in 98 pigs (75 of PLW PL and 25 [PLW PL] Pietrain crosses). The determined meat characteristics covered the pH1 and pHu records, visual assessment of colour and exudation on fresh meat samples, water holding capacity, drip loss, spectrophotometric measurements of dominant wavelength, colour saturation and lightness, L, a*, b* values according to the CIE system, basic chemical constituents (water, protein, intramuscular fat and ash) and soluble protein fraction in meat. The distribution of animals within particular MyoD genotypes only in the MYF4 and MYF5 genotypes were spread uniformly. The gene effects at particular MyoD loci on studied meat traits were significant. The most pronounced effect on meat quality was exerted by the myogenin gene (MYF4). Individuals of the BB genotype in respect to the MYF4 locus showed a better water holding capacity (P<0.01), lower drip loss (P<0.05), darker colour score (P<0.01) and better wateriness score (P<0.01), darker and more desirable colour characteristic (P<0.01) than pigs with the AA genotype, whereas AB genotype animals had intermediate values. In respect to meat protein solubility the AA genotype pigs had a significantly lower level of soluble protein in meat than AB and BB (P<0.01). On basis of the present study it may be inferred that mutations in coding and the non-coding regions of MyoD genes exert significant effects on muscle traits related to oxidative metabolism, as well as related to glycolysis and contractile muscle properties, and thereby on meat quality.

A new SNP in the promoter region of the porcine MYF5 gene has no effect on its transcript level in m. longissimus dorsi

Myogenic factor 5 (myf-5) is the product of theMYF5 gene, belonging to theMyoD family. This transcription factor participates in the control of myogenesis. We identified 3 new mutations in the promoter region of the gene:A65 C, C580T andC613T. The aim of this study was to evaluate the influence of theA65C transversion on gene expression. The analysis was conducted on 15 Polish Large White gilts. The relative content ofMYF5 mRNA inm. longissimus dorsi did not differ significantly acrossMYF5 genotypes (AA, AC, CC). This result suggests that theA65C transversion may not play an important role in the expression of theMYF5 gene in analysed adult muscle but it abolishes a putative binding site for two transcription factors (CDP and HSF1) and creates such a site for Sp1.

Note: Partial Sequence of Porcine MYF6 Gene, Its Comparative Analysis and a Novel Polymorphism of the Region Coding for the Basic Domain

Myogenic factor 6 (Myf-6, MRF4), the product of the MYF6 gene, is a member of the MyoD family of four transcription factors (Myf-3, Myf-5, myogenin, and Myf-6) controlling the processes of myogenesis. These factors are typical basic helix-loop-helix (bHLH) proteins, which can induce expression of muscle specific genes and convert a large number of different nonmuscle cells into muscle (Buckingham, 1992; Weintraub et al., 1991a). The bHLH structure is typical for the whole family of growth and development factors and consists of a basic domain that binds DNA at the E-box site, and an HLH domain needed for dimerization (Murre et al., 1989). The expression of the MYF6 gene occurs in the later stages of myogenesis, is preceded by myogenin expression, and accompanies the processes of differentiation and maturation of myotubes (Braun et al., 1990a; Miner and Wold, 1990; Olson et al., 1996; Rhodes and Konieczny, 1989; Vivian et al., 2000). The MYF6 gene and its product show a high structure similarity to the other MyoD family members. All four genes are composed of three exons and share homology within the region coding for bHLH domain (Braun et al., 1990a; Fujisawa-Sehara et al., 1990). The DNA sequence of MYF6 is known in the human, mouse, and rat but not in swine. The present study was performed to sequence a portion of the porcine MYF6 coding region and examine polymorphism in these regions of MYF6 gene. The study is a part of a project aimed at evaluating the effect of the porcine MYF6 gene polymorphism on carcass lean content.

The differences in plasma protein pattern between laying and non-laying chickens, quails and geese☆

Abstract 1. 1. The pattern of proteins in blood plasma of chicken, quail and goose was studied in relation to egg laying. 2. 2. The method of horizontal polyacrylamide gradient gel electrophoresis with a 12% separation gel and a discontinuous buffer system (Tris-citrate-borate pH 9.0) was used. 3. 3. Considerable differences in the protein patterns between laying and non-laying birds in four regions of plasma proteins: prealbumin, pretransferrin, post-transferrin and γ-globulin were noticed.