scholarly journals 107 Skeletal muscle mitochondrial parameters correlate with sales price in weanling racing-bred Thoroughbred horses

2020 ◽  
Vol 98 (Supplement_4) ◽  
pp. 86-86
Author(s):  
Chloey P Guy ◽  
Christine M Latham ◽  
Randi N Owen ◽  
Ashley L Fowler ◽  
Sarah H White-Springer
Keyword(s):  
Skeletal Muscle ◽  
Complex I ◽  
Citrate Synthase ◽  
Pearson Correlation ◽  
Coupling Efficiency ◽  
Gluteus Medius ◽  
Volume Density ◽  
Sales Price ◽  
Correlation Statistics ◽  
Race Performance

Abstract Thoroughbred horse sales prices rely heavily on animal conformation and ancestral race performance, as well as the current economic landscape. However, little information exists on the relationship between physiological parameters and sales price. We aimed to test the hypothesis that weanling sales price would positively correlate with skeletal muscle mitochondrial parameters in racing-bred Thoroughbreds. Gluteus medius muscle samples were collected from racing-bred Thoroughbred weanlings (n = 19; mean ± SD; 5.7 ± 0.3 mo) and evaluated for mitochondrial volume density (citrate synthase activity; CS) and function (cytochrome c oxidase activity; COX) by colorimetry, and oxidative and electron transport system capacities by high resolution respirometry. Horses were sold at the 2018 and 2019 Keeneland November Breeding Stock Sales at 8.5 ± 0.7 mo of age. Data were analyzed using Pearson Correlation Statistics in SAS (v9.4). Weanling sales price was positively correlated with intrinsic mitochondrial function (COX activity per unit CS; r = 0.6269, P = 0.004) and coupling efficiency with substrates for complex I+II (r = 0.4424, P = 0.05). A trend for a negative correlation was observed between weanling sales price and CS activity (r = -0.4179, P = 0.07), while a trend for a positive correlation between sales price and intrinsic oxidative phosphorylation capacity with complex I substrates (r = 0.3974, P = 0.09) was observed. In this cohort of weanling Thoroughbreds, mitochondrial parameters measured at 6 mo of age correlated with sales price at 8 mo of age. Implications of these relationships as they relate to race performance should be further investigated.

scholarly journals 108 President Oral Presentation Pick: Select skeletal muscle mitochondrial measures in Thoroughbred weanlings are related to race earnings and sire

2020 ◽  
Vol 98 (Supplement_4) ◽  
pp. 85-85
Author(s):  
Chloey P Guy ◽  
Christine M Latham ◽  
Randi N Owen ◽  
Ashley L Fowler ◽  
Sarah H White-Springer
Keyword(s):  
Skeletal Muscle ◽  
Complex I ◽  
Fixed Effects ◽  
Linear Models ◽  
Citrate Synthase ◽  
Pearson Correlation ◽  
Gluteus Medius ◽  
Volume Density ◽  
Complex Ii ◽  
And Training

Abstract Quantifiable, cellular differences of individuals are not widely used in breeding and training decisions in the equine industry. Our objective was to determine if mitochondrial parameters in weanling Thoroughbreds were related to sire or lifetime race earnings. We hypothesized that weanling skeletal muscle mitochondrial capacity would be positively correlated with race earnings. Gluteus medius muscle samples were collected from racing-bred Thoroughbred weanlings (n = 139; mean ± SD; 6.0 ± 0.4 mo) from 40 different sires over 3 years at 5 different farms and evaluated for mitochondrial volume density (citrate synthase activity; CS) and function (cytochrome c oxidase activity) by colorimetry, and oxidative (P) and electron transport system (E) capacities by high resolution respirometry; two- and three-year-old race earnings were available for a subset of 13 horses. Data were analyzed using mixed linear models with sire, sex, year of collection, and farm as fixed effects. Correlations between lifetime race earnings and mitochondrial measures were determined using Pearson Correlation Statistics. A main effect of sire was observed for weanling intrinsic (relative to CS activity) P with complex I substrates (P = 0.04) and the contribution of mitochondrial leak to O2 consumption (FCRL; P = 0.04). A trend was observed for the effect of sire on intrinsic mitochondrial leak (P = 0.09). Race earnings were positively correlated with integrated (relative to mg protein) leak (r = 0.7684, P = 0.009) and FCRL (r = 0.7035; P = 0.02). A trend for a negative correlation between E with complex II substrates and race earnings was also observed (r = -0.4775, P = 0.09), No other measures were influenced by sire, nor were correlated with race earnings. Our previous work has indicated a preferential use of complex I in breeds bred for short-duration racing (Thoroughbreds) compared to distance racing breeds (Standardbreds) that relied more heavily on complex II. Mitochondrial measures in weanlings may be utilized to inform future breeding and training decisions in horses.

scholarly journals RAPID COMMUNICATION: Differential skeletal muscle mitochondrial characteristics of weanling racing-bred horses1

2019 ◽  
Vol 97 (8) ◽  
pp. 3193-3198 ◽  
Author(s):  
Christine M Latham ◽  
Clara K Fenger ◽  
Sarah H White
Keyword(s):  
Skeletal Muscle ◽  
Electron Transport ◽  
Transport System ◽  
Complex I ◽  
Management Practices ◽  
Citrate Synthase ◽  
Fiber Type ◽  
Gluteus Medius ◽  
Electron Transport System ◽  
Mitochondrial Density

Abstract Responses of equine skeletal muscle characteristics to growth and training have been shown to differ between breeds. These differential responses may arise in part because muscle fiber type and mitochondrial density differ between breeds, even in untrained racing-bred horses. However, it is not known when these breed-specific differences manifest. To test the hypothesis that weanling Standardbreds (SB) and Thoroughbreds (TB) would have higher mitochondrial measures than Quarter Horses (QH), gluteus medius samples were collected from SB (mean ± SD; 6.2 ± 1.0 mo; n = 10), TB (6.1 ± 0.5 mo; n = 12), and QH (7.4 ± 0.6 mo; n = 10). Citrate synthase (CS) and cytochrome c oxidase (CCO) activities were assessed as markers of mitochondrial density and function, respectively. Mitochondrial oxidative (P) and electron transport system (E) capacities were assessed by high-resolution respirometry (HRR). Data for CCO and HRR are expressed as integrated (per mg protein and per mg tissue wet weight, respectively) and intrinsic (per unit CS). Data were analyzed using PROC MIXED in SAS v 9.4 with breed as a fixed effect. Mitochondrial density (CS) was higher for SB and TB than QH (P ≤ 0.0007). Mitochondrial function (integrated and intrinsic CCO) was higher in TB and QH than SB (P ≤ 0.01). Integrated CCO was also higher in TB than QH (P < 0.0001). However, SB had higher integrated maximum P (PCI+II) and E (ECI+II) than QH (P ≤ 0.02) and greater integrated and intrinsic complex II-supported E (ECII) than both QH and TB (P ≤ 0.02), whereas TB exhibited higher integrated P with complex I substrates (PCI) than SB and QH (P ≤ 0.003) and higher integrated PCI+II and ECI+II than QH (P ≤ 0.02). In agreement, TB and QH had higher contribution of complex I (CI) to max E than SB (P ≤ 0.001), whereas SB had higher contribution of CII than QH and TB (P ≤ 0.002). Despite having higher mitochondrial density than QH and TB, SB showed lower CCO activity and differences in contribution of complexes to oxidative and electron transport system capacities. Breed differences in mitochondrial parameters are present early in life and should be considered when developing feeding, training, medication, and management practices.

241 Skeletal Muscle Mitochondrial Capacities Are Impacted by Breed and Temperament in Young Angus and Brahman Steers

2021 ◽  
Vol 99 (Supplement_3) ◽  
pp. 127-127
Author(s):  
Chloey P Guy ◽  
Lauren T Wesolowski ◽  
Audrey L Earnhardt ◽  
Dustin Law ◽  
Don A Neuendorff ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Fixed Effects ◽  
Linear Models ◽  
Citrate Synthase ◽  
Volume Density ◽  
Skeletal Muscle Mitochondria ◽  
Mitochondrial Volume ◽  
Mitochondrial Volume Density ◽  
Brahman Steers ◽  
The Impact

Abstract Temperament impacts skeletal muscle mitochondria in Brahman heifers, but this has not been investigated in steers or between cattle breeds. We hypothesized mitochondrial measures would be greater in Angus than Brahman, temperamental than calm steers, and the trapezius (TRAP) than the longissimus thoracis (LT) muscle. Samples from calm (n = 13 per breed), intermediate (n = 12 per breed), and temperamental (n=13 per breed) Angus and Brahman steers (mean±SD 10.0±0.8 mo) were evaluated for mitochondrial enzyme activities via colorimetry. Calm and temperamental LT samples were evaluated for oxidative phosphorylation (P) and electron transfer (E) capacities by high-resolution respirometry. Data were analyzed using linear models with fixed effects of breed, muscle, temperament, and all interactions. Brahman tended to have greater mitochondrial volume density (citrate synthase activity; CS) than Angus (P = 0.08), while intrinsic (relative to CS) mitochondrial function (cytochrome c oxidase activity) was greater in Angus than Brahman (P = 0.001) and greater in TRAP than LT (P = 0.008). Angus exhibited greater integrative (per mg tissue) and intrinsic P with complex I (PCI), P with complexes I+II (PCI+II), maximum noncoupled E, and E with complex II (ECII; P ≤ 0.04) and tended to have greater intrinsic leak (P = 0.1) than Brahman. Contribution of PCI to total E was greater in Angus than Brahman (P = 0.01), while contribution of ECII to total E was greater in Brahman than Angus (P = 0.05). A trend for the interaction of breed and temperament (P = 0.07) indicated calm Angus had the greatest intrinsic ECII (P ≤ 0.03) while intrinsic ECII was similar between temperamental Angus and calm and temperamental Brahman. Integrative PCI+II and ECII, and the contribution of PCI and PCI+II to overall E tended to be greater in temperamental than calm steers (P ≤ 0.09), while intrinsic ECII tended to be greater in calm than temperamental steers (P = 0.07). The impact of these mitochondrial differences on meat quality measures remains to be determined.

scholarly journals Temperament influences mitochondrial capacity in skeletal muscle from 8 through 18 mo of age in Brahman heifers

2020 ◽  
Vol 98 (10) ◽  
Author(s):  
Randi N Owen ◽  
Christine M Latham ◽  
Charles R Long ◽  
Ronald D Randel ◽  
Thomas H Welsh ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Product Quality ◽  
Repeated Measures ◽  
Complex I ◽  
Citrate Synthase ◽  
Serum Cortisol ◽  
System Capacity ◽  
Complex Ii ◽  
Potential Link ◽  
Muscle Groups

Abstract Temperamental cattle tend to yield carcasses of poorer quality, and Brahman cattle are reportedly more temperamental than non-indicus cattle breeds. A potential link between temperament and product quality may be mitochondrial activity. We hypothesized that mitochondrial measures would be greater in temperamental compared with calm heifers and that the relationships between temperament and mitochondria would persist as heifers age. Serum cortisol and skeletal muscle (longissimus thoracis [LT] and trapezius [TRAP]) mitochondrial profiles and antioxidant activities were quantified from the same calm (n = 6) and temperamental (n = 6) Brahman heifers at 8, 12, and 18 mo of age. Data were analyzed using a mixed model ANOVA in SAS (9.4) with repeated measures. Serum cortisol was greater in temperamental compared with calm heifers throughout the study (P = 0.02). Mitochondrial volume density (citrate synthase [CS] activity) increased over time (P < 0.0001) but was similar between temperament and muscle groups. Mitochondrial function (cytochrome c oxidase activity) was greatest in the temperamental LT at 8 mo of age (P ≤ 0.0006), greatest in the temperamental TRAP at 18 mo of age (P ≤ 0.003), and did not differ by temperament at 12 mo of age. Integrative (relative to tissue wet weight) mitochondrial oxidative phosphorylation capacity with complex I substrates (PCI), PCI plus complex II substrate (PCI+II), noncoupled electron transfer system capacity (ECI+II), and E with functional complex II only (ECII) were greater in the TRAP than LT for calm heifers at all ages (P ≤ 0.002), but were similar between muscle groups in temperamental heifers. Overall, calm heifers tended to have greater intrinsic (relative to CS activity) PCI and flux control of PCI+II (P ≤ 0.1) than temperamental heifers, indicating greater utilization of complex I paired with greater coupling efficiency in calm heifers. Within the LT, integrative PCI+II was greater (P = 0.05) and ECI+II tended to be greater (P = 0.06) in temperamental compared with calm heifers. From 8- to 18-mo old, glutathione peroxidase (GPx) activity decreased (P < 0.0001) and superoxide dismutase activity increased (P = 0.02), and both were similar between muscle groups. The activity of GPx was greater in temperamental compared with calm heifers at 8 (P = 0.004) but not at 12 or 18 mo of age. These results detail divergent skeletal muscle mitochondrial characteristics of live Brahman heifers according to temperament, which should be further investigated as a potential link between temperament and product quality.

scholarly journals Adaptations in Mitochondrial Enzymatic Activity Occurs Independent of Genomic Dosage in Response to Aerobic Exercise Training and Deconditioning in Human Skeletal Muscle

Cells ◽  
2019 ◽  
Vol 8 (3) ◽  
pp. 237 ◽  
Author(s):  
Andreas Fritzen ◽  
Frank Thøgersen ◽  
Kasper Thybo ◽  
Christoffer Vissing ◽  
Thomas Krag ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Exercise Training ◽  
Enzymatic Activity ◽  
Endurance Exercise ◽  
Complex I ◽  
Citrate Synthase ◽  
Knee Extensor ◽  
Mitochondrial Complex ◽  
Membrane Markers ◽  
Endurance Exercise Training

Mitochondrial DNA (mtDNA) replication is thought to be an integral part of exercise-training-induced mitochondrial adaptations. Thus, mtDNA level is often used as an index of mitochondrial adaptations in training studies. We investigated the hypothesis that endurance exercise training-induced mitochondrial enzymatic changes are independent of genomic dosage by studying mtDNA content in skeletal muscle in response to six weeks of knee-extensor exercise training followed by four weeks of deconditioning in one leg, comparing results to the contralateral untrained leg, in 10 healthy, untrained male volunteers. Findings were compared to citrate synthase activity, mitochondrial complex activities, and content of mitochondrial membrane markers (porin and cardiolipin). One-legged knee-extensor exercise increased endurance performance by 120%, which was accompanied by increases in power output and peak oxygen uptake of 49% and 33%, respectively (p < 0.01). Citrate synthase and mitochondrial respiratory chain complex I–IV activities were increased by 51% and 46–61%, respectively, in the trained leg (p < 0.001). Despite a substantial training-induced increase in mitochondrial activity of TCA and ETC enzymes, there was no change in mtDNA and mitochondrial inner and outer membrane markers (i.e. cardiolipin and porin). Conversely, deconditioning reduced endurance capacity by 41%, muscle citrate synthase activity by 32%, and mitochondrial complex I–IV activities by 29–36% (p < 0.05), without any change in mtDNA and porin and cardiolipin content in the previously trained leg. The findings demonstrate that the adaptations in mitochondrial enzymatic activity after aerobic endurance exercise training and the opposite effects of deconditioning are independent of changes in the number of mitochondrial genomes, and likely relate to changes in the rate of transcription of mtDNA.

scholarly journals Mitochondrial Function in Oxidative and Glycolytic Bovine Skeletal Muscle Postmortem

2019 ◽  
Vol 3 (2) ◽  
Author(s):  
P. Ramos ◽  
L. Bell ◽  
S. Wohlgemuth ◽  
T. Scheffler
Keyword(s):  
Cytochrome C ◽  
Oxidative Phosphorylation ◽  
Outer Membrane ◽  
Functional Properties ◽  
Mitochondrial Function ◽  
Complex I ◽  
Fixed Effects ◽  
Citrate Synthase ◽  
Electron Flow ◽  
Coupling Efficiency

ObjectivesMitochondrial function in postmortem muscle is affected by decreasing oxygenation. Functional properties relating to energy production and integrity of mitochondria may influence development of meat quality characteristics. Therefore, the objective was to evaluate changes in mitochondrial function in oxidative and glycolytic muscles during the first 24h postmortem.Materials and MethodsSteers (n = 6) of primarily Angus (80 to 100%) genetics were harvested at approximately 18.5 mo and 630 kg live weight. Samples from the longissimus lumborum (LL) and diaphragm (Dia) were collected at 1, 3, and 24h postmortem. Fresh-preserved muscle samples were permeabilized using saponin, and muscle bundles (2–4 mg) were transferred to a high-resolution oxygraph for respiration measurements (oxygen consumption rate, OCR, pmol/sec/mg of tissue). Samples were assessed in duplicate under hyperoxia. First, pyruvate and malate were added to support the TCA cycle and assess leak respiration. Then, ADP was added to support electron flow through complex I. The influence of glutamate on NADH production (complex I) was tested, followed by complex II activation by succinate. Integrity of the mitochondria outer membrane was tested with cytochrome c. Next, an uncoupler (FCCP) was added to force the electron transport system (ETS) to maximum capacity. Citrate synthase (CS) activity (nmol/min/mg tissue) was determined in frozen samples and used as a marker of mitochondria content. Subsequently, respiration data were normalized to CS activity (pmol/sec/U CS) to account for differences in mitochondria content. Coupling efficiency of oxidative phosphorylation was calculated as 1– (Leak/ADP-stimulated oxidative phosphorylation capacity). Raw and normalized OCR were analyzed in a randomized block design, with slaughter date as block and fixed effects of muscle, time, and the interaction. Time was considered a repeated measure.ResultsMuscle type affected (P = 0.0002) leak OCR, with Dia showing a higher rate than LL. After ADP was added, mitochondria from Dia exhibited higher OCR at all times tested and at all steps, with OCR being 4 times higher after FCCP addition. Mitochondrial content, evidenced by greater (P < 0.0001) CS activity in Dia, largely explained differences in OCR between muscles. After OCR was normalized to CS activity, the 1 and 3h postmortem OCR from Dia and LL were similar (P > 0.05). However, at 24h postmortem, OCR after ADP, glutamate, and FCCP additions were greater (P < 0.05) in Dia mitochondria. Time, but not muscle, affected cytochrome c response. At 1h postmortem, cytochrome c increased OCR by 6.6%, supporting that mitochondria outer membrane integrity is not compromised. However, cytochrome c response at 3h postmortem increased 52.4%, indicating outer membrane damage. Coupling efficiency is different between muscles (P = 0.005) with Dia exhibiting greater efficiency.ConclusionDespite inherent metabolic differences between the LL and Dia, mitochondria from both muscles are intact and coupled at 1h postmortem. However, by 24h postmortem, functional properties of LL mitochondria are reduced compared to Dia. Declining mitochondrial function may be associated with calcium overload, mitochondrial fragmentation, and protease activation.

scholarly journals Skeletal muscle metabolism in sea-acclimatized king penguins. II. Improved efficiency of mitochondrial bioenergetics

2020 ◽  
Vol 223 (21) ◽  
pp. jeb233684
Author(s):  
Damien Roussel ◽  
Vincent Marmillot ◽  
Pierre-Axel Monternier ◽  
Aurore Bourguignon ◽  
Gaëlle Toullec ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Respiratory Chain ◽  
Citrate Synthase ◽  
Coupling Efficiency ◽  
Chain Complex ◽  
Atp Synthesis ◽  
Respiratory Chain Complexes ◽  
Marine Habitat ◽  
Muscle Mitochondria

ABSTRACTAt fledging, juvenile king penguins (Aptenodytes patagonicus) must overcome the tremendous energetic constraints imposed by their marine habitat, including during sustained extensive swimming activity and deep dives in cold seawater. Both endurance swimming and skeletal muscle thermogenesis require high mitochondrial respiratory capacity while the submerged part of dive cycles repeatedly and greatly reduces oxygen availability, imposing a need for solutions to conserve oxygen. The aim of the present study was to determine in vitro whether skeletal muscle mitochondria become more ‘thermogenic’ to sustain heat production or more ‘economical’ to conserve oxygen in sea-acclimatized immature penguins (hereafter ‘immatures’) compared with terrestrial juveniles. Rates of mitochondrial oxidative phosphorylation were measured in permeabilized fibers and mitochondria from the pectoralis muscle. Mitochondrial ATP synthesis and coupling efficiency were measured in isolated muscle mitochondria. The mitochondrial activities of respiratory chain complexes and citrate synthase were also assessed. The results showed that respiration, ATP synthesis and respiratory chain complex activities in pectoralis muscles were increased by sea acclimatization. Furthermore, muscle mitochondria were on average 30–45% more energy efficient in sea-acclimatized immatures than in pre-fledging juveniles, depending on the respiratory substrate used (pyruvate, palmitoylcarnitine). Hence sea acclimatization favors the development of economical management of oxygen, decreasing the oxygen needed to produce a given amount of ATP. This mitochondrial phenotype may improve dive performance during the early marine life of king penguins, by extending their aerobic dive limit.

scholarly journals Enhanced Skeletal Muscle Oxidative Capacity and Capillary-to-Fiber Ratio Following Moderately Increased Testosterone Exposure in Young Healthy Women

2020 ◽  
Vol 11 ◽  
Author(s):  
Daniele A. Cardinale ◽  
Oscar Horwath ◽  
Jona Elings-Knutsson ◽  
Torbjörn Helge ◽  
Manne Godhe ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Complex I ◽  
Citrate Synthase ◽  
Mitochondrial Protein ◽  
Capillary Density ◽  
Oxidative Capacity ◽  
System Capacity ◽  
Endurance Capacity ◽  
Muscle Oxidative Capacity ◽  
Before And After

Background: Recently, it was shown that exogenously administered testosterone enhances endurance capacity in women. In this study, our understanding on the effects of exogenous testosterone on key determinants of oxygen transport and utilization in skeletal muscle is expanded.Methods: In a double-blinded, randomized, placebo-controlled trial, 48 healthy active women were randomized to 10 weeks of daily application of 10 mg of testosterone cream or placebo. Before and after the intervention, VO2 max, body composition, total hemoglobin (Hb) mass and blood volumes were assessed. Biopsies from the vastus lateralis muscle were obtained before and after the intervention to assess mitochondrial protein abundance, capillary density, capillary-to-fiber (C/F) ratio, and skeletal muscle oxidative capacity.Results: Maximal oxygen consumption per muscle mass, Hb mass, blood, plasma and red blood cell volumes, capillary density, and the abundance of mitochondrial protein levels (i.e., citrate synthase, complexes I, II, III, IV-subunit 2, IV-subunit 4, and V) were unchanged by the intervention. However, the C/F ratio, specific mitochondrial respiratory flux activating complex I and linked complex I and II, uncoupled respiration and electron transport system capacity, but not leak respiration or fat respiration, were significantly increased following testosterone administration compared to placebo.Conclusion: This study provides novel insights into physiological actions of increased testosterone exposure on key determinants of oxygen diffusion and utilization in skeletal muscle of women. Our findings show that higher skeletal muscle oxidative capacity coupled to higher C/F ratio could be major contributing factors that improve endurance performance following moderately increased testosterone exposure.

scholarly journals Mitochondrial oxygen consumption in early postmortem permeabilized skeletal muscle fibers is influenced by cattle breed

2020 ◽  
Vol 98 (3) ◽  
Author(s):  
Patricia M Ramos ◽  
Chengcheng Li ◽  
Mauricio A Elzo ◽  
Stephanie E Wohlgemuth ◽  
Tracy L Scheffler
Keyword(s):  
Skeletal Muscle ◽  
Oxygen Consumption ◽  
Oxidative Phosphorylation ◽  
Heat Tolerance ◽  
Complex I ◽  
Citrate Synthase ◽  
Ex Vivo ◽  
Muscle Fibers ◽  
Cattle Breed ◽  
Early Postmortem

Abstract Functional properties and integrity of skeletal muscle mitochondria (mt) during the early postmortem period may influence energy metabolism and pH decline, thereby impacting meat quality development. Angus typically produce more tender beef than Brahman, a Bos indicus breed known for heat tolerance. Thus, our objectives were to compare mt respiratory function in muscle collected early postmortem (1 h) from Angus and Brahman steers (n = 26); and to evaluate the effect of normal and elevated temperature on mt function ex vivo. We measured mt oxygen consumption rate (OCR) in fresh-permeabilized muscle fibers from Longissimus lumborum (LL) at 2 temperatures (38.5 and 40.0 °C) and determined citrate synthase (CS) activity and expression of several mt proteins. The main effects of breed, temperature, and their interaction were tested for mt respiration, and breed effect was tested for CS activity and protein expression. Breed, but not temperature (P &gt; 0.40), influenced mt OCR (per tissue weight), with Brahman exhibiting greater complex I+II-mediated oxidative phosphorylation capacity (P = 0.05). Complex I- and complex II-mediated OCR also tended to be greater in Brahman (P = 0.07 and P = 0.09, respectively). Activity of CS was higher in LL from Brahman compared to Angus (P = 0.05). Expression of specific mt proteins did not differ between breeds, except for higher expression of adenosine triphosphate (ATP) synthase subunit 5 alpha in Brahman muscle (P = 0.04). Coupling control ratio differed between breeds (P = 0.05), revealing greater coupling between oxygen consumption and phosphorylation in Brahman. Our data demonstrate that both Angus and Brahman mt retained functional capacity and integrity 1-h postmortem; greater oxidative phosphorylation capacity and coupling in Brahman mt could be related to heat tolerance and impact early postmortem metabolism.

scholarly journals PSV-25 Mitochondrial function of skeletal muscle early postmortem is influenced by cattle breed and temperature

2019 ◽  
Vol 97 (Supplement_3) ◽  
pp. 334-334
Author(s):  
Patricia Ramos ◽  
Chengcheng Li ◽  
Mauricio Elzo ◽  
Stephanie Wohlgemuth ◽  
Tracy Scheffler
Keyword(s):  
Skeletal Muscle ◽  
Meat Quality ◽  
Heat Tolerance ◽  
Mitochondrial Function ◽  
Complex I ◽  
Citrate Synthase ◽  
Bos Taurus ◽  
Cattle Breed ◽  
Longissimus Lumborum ◽  
Early Postmortem

Abstract Functional properties and integrity of skeletal muscle mitochondria during the early postmortem period may influence development of meat quality traits, such as tenderness. Angus typically produce more tender beef than Brahman, a Bos taurus indicus subspecies known for heat tolerance. Thus, our objectives were to assess mitochondrial function in muscle collected early postmortem from Angus and Brahman cattle; and to evaluate the effect of normal and elevated temperature on mitochondria function. Longissimus lumborum was collected at 1h postmortem from Angus and Brahman steers, and high resolution respirometry was used to assess mitochondrial function in permeabilized muscle fibers at two temperatures (38.5 and 40.0°C). The main effects of breed, temperature, and their interaction were tested. On a tissue weight basis, parameters of respiratory function were not influenced by breed or temperature, though Brahman exhibited numerically greater values for respiration supported by complex I, complex I+II, and complex II substrates. Citrate synthase activity, a marker of mitochondria content, was affected by breed (P = 0.049). Consequently, oxygen consumption rate (OCR) data were normalized to citrate synthase activity. After normalization for mitochondrial content, the overall mitochondria OCR pattern changed, revealing differences among breeds for proton leak respiration (P = 0.045), as well as a persistent interaction effect primarily related to reduced OCR in mitochondria from Brahman at 40.0°C. In addition, the ratio of OCR for leak relative to complex I+II phosphorylation was lower in Brahman, evidencing greater coupling. However, mean coupling ratios for both Angus and Brahman support that respiration and phosphorylation were well-coupled for both breeds even at 1h postmortem. Thus, mitochondria retain functional capacity and integrity at 1h postmortem; and mitochondria properties may be related to differences in heat tolerance and meat quality development between cattle subspecies.

Sign in / Sign up

Export Citation Format

Share Document