Date of Graduation

7-2020

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Food Science (PhD)

Degree Level

Graduate

Department

Food Science

Advisor/Mentor

Charles V. Maxwell

Committee Member

Navam Hettiarachchy

Second Committee Member

Zelpha B. Johnson

Third Committee Member

Gisela F. Erf

Fourth Committee Member

Luke Howard

Keywords

Complex (Cx), Feed efficiency, Longissimus muscle (LM), Mitochondria isolated, Respiratory Chain Activity, Spinalis dorsi muscle (SpD)

Abstract

Current as well as past studies have provided evidence for a connection between macroeconomic/agricultural and cellular/biochemical basis of feed efficiency (FE; gain:feed) in farm animal production. Our investigation of respiratory chain activity, mitochondrial protein oxidation and protein expression was an expansion to the subcellular/molecular level. In this study we investigated the entire complex (Cx) of the electron transport chain (ETC) for differences in Cx activities in mitochondria isolated from skeletal muscle in high (HFE) and low (LFE) feed efficient swine within the same genetic line. Review of literature provided information for the connection between feed efficiency, mitochondrial function, and muscle type. Using UV spectrophotometry, gel electrophoresis and western blotting methods, we were able to study mitochondria from swine Longissimus (LM) and Spinalis dorsi muscles for differences in respiratory chain complex (I - V) activities, protein oxidation and protein expression of eleven subunits of the five electron transport chain complexes. We observed muscle dependent differences in Cx I and II, protein carbonyls and five subunits of the ETC (Cx I 30, Cor II, Cox IV, alpha and beta ATPase). We concluded after comparing our results with findings in literature, that respiratory chain activity protein oxidation and expression of protein subunits may be both skeletal muscle as well as a species dependent. These differential expressions may be the result of increased incidents of reactive oxygen species causing defects in Cx I or Cx II that may precipitate significant mitochondrial events and cellular pathways that provide links to the phenotypic expression of feed efficiency. Of high interest in relation to the mitochondrial link to FE are apoptotic, mTor and myostatin pathways.

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