Suppressive subtractive hybridization (SSH) was used to analyse the muscle transcriptome and identify genes affecting meat quality within an Italian pig population of Large White and Landrace ...purebred individuals. Seven phenotypes were recorded at slaughter: dorsal fat thickness, ham fat thickness, ham fat coverage, muscle compactness, marbling, meat colour and colour uniformity. Two subtractive libraries were created from longissimus dorsi tissue of selected pigs with extreme phenotypes for meat quality. Eighty-four differentially expressed ESTs were identified, which showed homology to expressed pig sequences and/or to genomic pig sequences produced within the pig genome project. Sixty-eight sequences were mapped on the pig genome, and most of these sequences co-localized with the same chromosomal positions as QTLs that have been previously identified for meat quality. Thirty sequences, including eight matching known genes previously related to muscle metabolic pathways, were selected to statistically validate their differential expression. Association analysis and t-test results indicated that 28 ESTs of the 30 analysed were associated with phenotypes investigated here and have significant differential expression levels (P ≤ 0.05) between the two tails of the phenotypic distribution.
In order to identify candidate genes and molecular mechanisms that influence meat quality and production in pigs, microarray experiments were carried out to find differences in gene expression levels ...between two pools of six individuals, constituting the extreme tails of the Gaussian distribution of seven adjusted phenotypes of 100 Landrace and Large White animals. The phenotypes considered in this study were: muscle compactness, marbling, colour uniformity, fat covering, colour, dorsal fat, thickness, ham fat thickness. 437 differentially expressed ESTs (Expressed Sequence Tags) were found, clustering in different pathways according to their ontology. In particular, 73 functional categories were identified and ten of them could have a role in meat quality. Among the ESTs belonging to these pathways, seven of them were selected to be validated in quantitative real-time RT-PCR.
The suppressive subtractive hybridization technique was previously used by the authors to identify candidate genes for meat quality in pig. A set of ESTs homologous (>95%) to genes involved in muscle ...metabolism is reported in the present paper. Four ESTs homologous to MYH1, KALRN, MLC2V, and SNX13 genes plus two genes (AK1, PPIA) used as housekeeping for muscle tissue were assigned to porcine chromosomes using the INRA-Minnesota 7000 rads radiation hybrid panel (IMpRH). Our data confirm and refine the cytogenetic position of the KALRN, AK1, PPIA genes, improve the existing physical map of MYH1 and assign two new genes (MLC2V and SNX13) to swine chromosomes.
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