Biomedical subjects

C Ojano-Dirain

Publications and source records attributed to C Ojano-Dirain.

5 recordsLinked to original sources

PubMed2006

Feed efficiency and mitochondrial function.

Studies have been conducted in our laboratory to assess differences in mitochondrial function and biochemistry in male broilers with high and low feed efficiency (FE) from the same genetic line and fed the same diet. Mitochondria obtained from broilers with low FE exhibited greater uncoupling of the electron transport chain (ETC) that was apparently due to site-specific defects in electron transport resulting in higher amounts of reactive oxygen species (ROS) compared with high FE mitochondria. Higher amounts of ROS production in Low FE mitochondria were likely responsible for higher protein carbonyl levels, indicative of higher protein oxidation compared with High FE mitochondria and tissue. In turn, higher protein damage in Low FE mitochondria may have contributed to lower activity of electron transport chain complexes relative to values observed in high FE mitochondria. Low FE mitochondria did not exhibit a compromised ability to carryout oxidative phosphorylation, and although there were differences in expression of certain electron transport chain proteins, there was nothing that would indicate that differences in coupling and respiratory chain activity could be due to a general decrease in protein expression between low and high FE mitochondria. The results of these studies provide insight into understanding cellular mechanisms associated with the phenotypic expression of feed efficiency in broilers.

Animal Feed↗

PubMed2006

Differential expression of mitochondrial and extramitochondrial proteins in lymphocytes of male broilers with low and high feed efficiency.

Studies were conducted to investigate relationships between mitochondrial and extramitochondrial protein expression, and protein oxidation in lymphocytes obtained from broilers in which individual feed efficiencies were obtained. Lymphocytes were isolated from male broilers from a single line that were shown to exhibit either low (0.48 +/- 0.02, n = 8) or high (0.68 +/- 0.01, n = 7) feed efficiency (FE). Western blot analysis showed that, compared with lymphocytes from high FE broilers, lymphocytes from low FE broilers exhibited a) higher amounts of oxidized proteins (protein carbonyls), b) lower amounts of 3 mitochondrial proteins [core I, cyt c 1 (complex III), and ATP synthase (complex V)], and c) higher amounts of 2 proteins [30 S (complex II) and COX II (complex IV)]. Two-dimensional gel electrophoresis revealed that the intensities of 25 protein spots from pooled samples of lymphocytes from high and low FE broilers differed by 5-fold or more. Three of these protein spots were picked from the gel and subjected to matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry analysis. One protein spot of ~33 kDa was tentatively identified by MALDI-TOF as a fragment of collapsin-2, a component of semaphorin 3D. The results of this study provide further evidence of increased oxidation associated with low FE and further evidence of differential protein expression associated with the phenotypic expression of feed efficiency.

Animal Feed↗

PubMed2005

Biochemical evaluation of mitochondrial respiratory chain in duodenum of low and high feed efficient broilers.

Increased H2O2 production, indicating higher oxidative stress, and lower mitochondrial function was previously observed in duodenal mitochondria isolated from broilers with low feed efficiency (FE, gain:feed). Thus, experiments were conducted to 1) evaluate the activity of the respiratory chain complexes (complexes I to V) and 2) assess protein oxidation and mitochondrial protein expression in broilers with low and high FE. Duodenal mitochondria were isolated from broiler breeders with low (0.52 +/- 0.01) and high (0.68 +/- 0.01) FE (n = 8/group). Respiratory chain complex activities were measured spectrophotometrically, whereas mitochondrial protein expression and protein oxidation (carbonyls) were assessed with Western blots. The activities of all complexes, except complex IV, were lower in the low FE compared with high FE mitochondria, whereas protein carbonyl levels were higher in low FE mitochondria. Steady-state levels of 6 out of 7 nuclear-encoded respiratory chain subunits [70S(FP), core I, core II, cytochrome c (cyt c)1, iron-sulfur protein (ISP), and ATPase-alpha] were higher, whereas 3 out of 6 mitochondrial-encoded subunits (ND4, ND6-C, and COX II) were lower in the low FE group, suggesting that sensitivity of mitochondrial proteins to H2O2 or oxidation varies. The general reduction in complex activity and differential protein expression concomitant with higher oxidized proteins in low FE mitochondria suggest that oxidative stress could be contributing to the lower mitochondrial function observed in low FE duodenal mitochondria.

Animal Feed↗

PubMed2005

Glutathione and respiratory chain complex activity in duodenal mitochondria of broilers with low and high feed efficiency.

We previously observed increased reactive oxygen species (ROS) production in intestinal mitochondria obtained from broiler breeder males with low feed efficiency (FE, gain-to-feed). Because antioxidants are critical for combating ROS-mediated oxidative stress and preserving mitochondrial function, the objectives of this study were 1) to determine levels of reduced glutathione (GSH), a major antioxidant in mitochondria, 2) to measure activities of GSH recycling enzymes: GSH peroxidase and GSH reductase, and 3) to establish relationships between antioxidants and respiratory chain complex activities (complexes I, II, III, IV, and V) in broiler breeder males with low and high FE. Duodenal mitochondria were isolated from broilers with low (0.62 +/- 0.01, n = 8) and high (0.80 +/- 0.01, n = 8) FE. Activities of respiratory chain complexes, GSH peroxidase, and GSH reductase, and levels of GSH were measured by UV spectrophotometry. There were no differences in GSH peroxidase or reductase activities or in individual complex activities between groups but GSH levels tended to be higher (P = 0.075) and oxidized to reduced glutathione ratio tended to be lower (P = 0.077) in broilers with high FE. Regression analysis revealed significant correlations (P < or = 0.05) between mitochondrial GSH and activities of complexes II, IV, and V with R2 values of 0.35, 0.56, and 0.49, respectively. These data suggest that GSH may be important in maintaining or enhancing the activity of certain respiratory chain complexes and could be involved in the phenotypic expression of feed efficiency in broilers.

Animals↗

PubMed2005

Compromised liver mitochondrial function and complex activity in low feed efficient broilers are associated with higher oxidative stress and differential protein expression.

Variations in broiler growth and efficiency have been explained in part by differences in mitochondrial function and biochemistry in broilers. To further our knowledge in this regard, 2 experiments were carried out to determine the relationships of a) mitochondrial function and activities of various electron transport chain (ETC) complexes; b) production of H2O2, a reactive oxygen species (ROS), and its association with protein oxidation; and c) mitochondrial protein expression in liver of a single line male broilers with low or high feed efficiency (FE, n = 5 to 8 per group). Mitochondrial function and complex activities were measured polarographically and spectrophotometrically, respectively. H2O2 was measured fluorimetrically, whereas oxidized protein (carbonyls) and specific mitochondrial proteins were analyzed using Western blots. Mitochondrial function (ETC coupling) and activities of ETC complexes (I, II, III, and IV) were higher in high FE compared with low FE broilers. H2O2 and protein carbonyls were higher in the livers of low FE broilers than in high FE broilers. Whereas the expression of 4 immunoreactive proteins [NAD3 (complex I), subunit VII (complex III), cytochrome c oxidase subunits (COX) II, and COX IVb (complex IV)] were higher in low FE liver mitochondria and 2 proteins [subunit 70 (complex II) and a-ATP synthase (complex V)] were higher in high FE birds, there were no differences between groups in the expression of 18 other mitochondrial proteins. In conclusion, increases in oxidative stress in low FE broilers were caused by or may contribute to differences in mitochondrial function (ETC coupling and complex activities) or the differential expression of steady-state levels of some mitochondrial proteins in the liver. Understanding the role of oxidative stress in Low FE broilers will provide clues in understanding the cellular basis of feed efficiency.

Animal Feed↗