Location: Meat Safety and QualityTitle: Potential relationship of the porcine muscle thanatotranscriptome to pork quality
|King, David - Andy|
|Nonneman, Danny - Dan|
Submitted to: International Congress of Meat Science and Technology Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 6/30/2020
Publication Date: 8/2/2020
Citation: King, D.A., Dickey, A.M., Shackelford, S.D., Wheeler, T.L., Rohrer, G.A., Nonneman, D.J. 2020. Potential relationship of the porcine muscle thanatotranscriptome to pork quality. [Abstract]. International Congress of Meat Science and Technology Proceedings. Poster No. 206.
Technical Abstract: Genome-wide association studies for pork quality traits that are defined antemortem (i.e. fatty acid profile) tend to yield clear QTL associations, while studies for traits affected by postmortem metabolism (i.e. color) are less clear. Most gene expression studies for identification of meat quality candidate genes involve tissues collected at death, though studies have reported many genes to be upregulated postmortem (thanatotranscriptome). Anaerobic glycolysis is considered the primary postmortem metabolic pathway in the conversion of muscle to meat; however, oxygen remains in postmortem muscle for hours to support mitochondrial function. The objectives of this study were to determine changes in gene expression within the postmortem interval and relate these affected genes and pathways to QTL for pork quality. Gilts (n = 5; 262 to 325 days of age) were harvested using electrical stunning and conventional chilling. Longissimus muscle samples were removed at 0, 24, and 48 hours postmortem. Samples for the 24- and 48- hour time periods were chilled as part of the carcass. From each sample, RNAseq libraries were prepared. An average of 58.5 million paired-end reads were collected from each library, mapped to Sscrofa 11.1 assembly and differential gene expression was determined using DESeq2. Compared to 0-hour samples, 4 and 1943 genes were more highly expressed, and 132 and 2280 were more lowly expressed at 24- and 48- hours, respectively, with log2 fold changes ranging from -7.15 to 2.55 compared to 0-hour. The most overrepresented pathways included ribosomal protein, protein translation, oxidative phosphorylation and cytochrome-C oxidase activity. Genes coding for mitochondrial complexes I (34 of 44), II (3 of 4), III (2 of 10), IV (19 of 9), and V (11 of 20) were more highly expressed at 48 hours postmortem than at death. These differentially expressed genes are primarily involved in electron transport, the TCA cycle, and ATP synthesis. Differentially expressed genes also included ribosomal proteins (85 of 109) as well as mitochondrial ribosomal proteins (40 of 77), suggesting an increase of translational capacity. ELISA for 3 proteins (HSPA6, CCL21 and EPB42) with gene expression fold changes of 5.1, 2.94 and 4.4 at 48 hours showed protein content changes of 88.01%, 42.19% and -37.17% at 48 hours, respectively. One hundred twenty more highly expressed genes at 48-hours postmortem were located within QTL associations for color, pH, water holding capacity and tenderness. These results imply that gene expression and protein translation continue to occur in postmortem muscle and could impact meat quality.