C. Ojano-Dirain

Mitochondrial proton leak kinetics and relationship with feed efficiency within a single genetic line of male broilers

Studies were conducted to assess proton leak kinetics (proton conductance) in breast muscle mitochondria isolated from broiler breeder males within a single genetic line exhibiting either high (HFE) or low (LFE) feed efficiency. Proton leak kinetics were determined by simultaneously measuring mitochondrial membrane potential and state 2 (resting) respiration rate in breast muscle mitochondria as succinate oxidation was progressively decreased by malonate. Control proton conductance was similar in HFE and LFE mitochondria and decreased to a similar extent in both groups in response to BSA. Although treatment of mitochondria with Glu or guanosine diphosphate had no effect, retinal increased and carboxyatractylate alone or in combination with Glu decreased proton conductance relative to control proton conductance in both HFE and LFE mitochondria. After treatment with either guanosine diphosphate or carboxyatractylate alone, proton conductance was lower in HFE compared with LFE mitochondria. With the exception of BSA, proton conductance in HFE mitochondria after the various chemical treatments was either less than or equal to, and never greater than, proton conductance in the LFE mitochondria. The results suggest that there are subtle differences in membrane characteristics (e.g., lipids, integral membrane proteins) that affect proton conductance in broiler muscle mitochondria that may in turn play a role in the phenotypic expression of feed efficiency.

Investigation of mitochondrial protein expression and oxidation in heart muscle in low and high feed efficient male broilers in a single genetic line

The objective of this study was to assess the expression of mitochondrial proteins and oxidized proteins in heart muscle homogenate obtained from male broilers exhibiting either high or low feed efficiency (G:F) phenotypes. Tissue homogenate was prepared from ventricular tissue obtained from broilers with high (0.80+/-0.01, n=8) and low (0.62+/-0.02, n=8) FE. The levels of specific immunoreactive proteins and oxidized proteins (carbonyls) were determined using Western blot analysis. The expression of 6 electron transport chain proteins [complex II, 70S subunit (CII 70S); iron-sulfur-containing protein (ISP), cytochrome b (Cyt b), cytochrome (Cyt c1) (of complex III); and cytochrome oxidase subunit II (COX II) (of complex IV)] and adenine nucleotide translocator 1 (ANT1) were higher in low feed efficiency heart mitochondria, but 1 protein [NAD subunit 6c (NAD6c) (complex I)] was higher in high feed efficiency birds. Protein carbonyl levels, indicative of oxidized proteins, were higher in heart tissue of low compared with high feed efficiency broilers.