• Comparative Proteomic Profiling of Divergent Phenotypes for Water Holding Capacity across the Post Mortem Ageing Period in Porcine Muscle Exudate

      Di Luca, Alessio; Hamill, Ruth; Mullen, Anne Maria; Slavov, Nikolai; Giuliano, Elia; Department of Agriculture, Food and the Marine, Ireland; 06RDNUIG470 (PLOS, 07/03/2016)
      Two dimensional Difference Gel Electrophoresis (2-D DIGE) and mass spectrometry were applied to investigate the changes in metabolic proteins that occur over a seven day (day 1, 3 and 7) post mortem ageing period in porcine centrifugal exudate from divergent meat quality phenotypes. The objectives of the research were to enhance our understanding of the phenotype (water holding capacity) and search for biomarkers of this economically significant pork quality attribute. Major changes in protein abundance across nine phenotype-by-time conditions were observed. Proteomic patterns were dominated by post mortem ageing timepoint. Using a machine learning algorithm (l1-regularized logistic regression), a model was derived with the ability to discriminate between high drip and low drip phenotypes using a subset of 25 proteins with an accuracy of 63%. Models discriminating between divergent phenotypes with accuracy of 72% and 73% were also derived comparing respectively, high drip plus intermediate phenotype (considered as one phenotype) versus low drip and comparing low drip plus intermediate phenotype (considered as one phenotype) versus high drip. In all comparisons, the general classes of discriminatory proteins identified include metabolic enzymes, stress response, transport and structural proteins. In this research we have enhanced our understanding of the protein related processes underpinning this phenotype and provided strong data to work toward development of protein biomarkers for water holding capacity.
    • Monitoring post mortem changes in porcine muscle through 2-D DIGE proteome analysis of Longissimus muscle exudate

      Di Luca, Alessio; Elia, Giuliano; Mullen, Anne Maria; Hamill, Ruth M; Department of Agriculture, Food and the Marine, Ireland; 06RDNUIG470 (Biomed Central, 20/03/2013)
      Background: Meat quality is a complex trait influenced by a range of factors with post mortem biochemical processes highly influential in defining ultimate quality. High resolution two-dimensional DIfference Gel Electrophoresis (2-D DIGE) and Western blot were applied to study the influence of post mortem meat ageing on the proteome of pork muscle. Exudate collected from the muscle following centrifugation was analysed at three timepoints representing a seven day meat ageing period. Results: The intensity of 136 spots varied significantly (p < 0.05) across this post mortem period and 40 spots were identified using mass spectrometry. The main functional categories represented were metabolic proteins, stress-related proteins, transport and structural proteins. Metabolic and structural proteins were generally observed to increase in abundance post mortem and many likely represent the accumulation of the degradation products of proteolytic enzyme activity. In contrast, stress-related proteins broadly decreased in abundance across the ageing period. Stress response proteins have protective roles in maintaining cellular integrity and a decline in their abundance over time may correlate with a reduction in cellular integrity and the onset of meat ageing. Since cellular conditions alter with muscle ageing, changes in solubility may also contribute to observed abundance profiles. Conclusions: Muscle exudate provided valuable information about the pathways and processes underlying the post mortem ageing period, highlighting the importance of post mortem modification of proteins and their interaction for the development of meat quality traits.