Altered development and protein metabolism in skeletal muscles of broiler chickens (Gallus gallus domesticus) by corticosterone

Two trials were conducted to investigate the effect of corticosterone (CORT) on protein metabolism and the amino acid composition in muscle tissues of broiler chickens (Gallus gallus domesticus). In Trial 1, two groups of 30 broiler chickens were subjected to control or CORT treatment (30 mg/kg diet) from 28 to 39 days of age. In Trial 2, three groups of chickens of 28 days of age were randomly subjected to one of the following treatments for 7 days: CORT (30 mg/kg diet), pair-fed (maintaining the same feed intake as CORT treatment) and control treatments. The body mass gain and feed efficiency was significantly decreased by CORT treatment, while the food intake was decreased. The breast and thigh masses (% body mass) were significantly suppressed by CORT treatment, while the abdominal fat and liver masses (%) were obviously increased. The plasma levels of glucose, urate and total amino acid were significantly elevated by CORT treatment. The capacity for protein synthesis, estimated by RNA:protein ratio, were significantly suppressed by CORT in M. pectoralis major and M. biceps femoris. The 3-methylhistidine concentrations were significantly increased in both M. pectoralis major and M. biceps femoris of CORT chickens, compared to control but not the pair-fed chickens. The amino acid composition of M. pectoralis major and M. biceps femoris was not significantly affected by CORT treatment. In conclusion, the arrested growth in skeletal muscles induced by CORT administration has tissue specificity. The CORT treatment retards the growth of skeletal muscle by suppressed protein synthesis and augmented protein catabolism.     

Muscle weights and succinic dehydrogenase distribution in the hind limb musculature of two rodents (Thryonomys gregorianus and Pedetes capensis) with different locomotory habits

The hind limb muscles of the spring hare (Pedetes capensis) were found to be relatively heavier than the hind limb muscles of the cane rat (Thryonomys gregorianus). The distribution of succine dehydrogenase activity was investigated in four of these muscles (m. gluteus superficialis, m.semimembranosus, m. biceps femoris and m.rectus femoris) from both animals. It was found that the spring hare had a higher proportion of low-activity fibres in all four muscles than the cane rat. All muscle fibre types were also smaller in diameter in the spring hare than the cane rat. These results are discussed in relation to the different locomotry habits of the two animals.     

Detection and isolation of a 30 kDa abnormal protein in avian dystrophic muscle

We have studied the protein composition of the pectoralis superficialis muscle of genetically dystrophic (New Hampshire line 413) and normal control (line 412) chickens by one- and two-dimensional gel electrophoresis. A protein, referred to hereafter as the 30 kDa abnormal protein, was specifically detected in the affected muscle. It was purified to homogeneity, and its molecular properties were studied. It is a monomer with a molecular mass of approximately 30 kDa and an isoelectric point of about pI 8.4. We have screened by Western blotting a variety of muscles from line 412 and line 413 chickens for the presence of the 30 kDa protein. While the pattern of total protein is very similar in all cases, the 30 kDa protein was not detected in the pectoralis superficialis muscle of line 412 chickens. However, the immunoreactive bands were detected in the sartorius muscle and the tensor fasciae latae muscle from dystrophic and normal chickens. Interestingly, the immunoreactive bands of normal skeletal muscles are smaller in molecular weight than those of dystrophic skeletal muscles. To determine the early time sequence of the appearance of the abnormal protein, we studied muscles from embryos and post-hatched chickens at various ages. The abnormal protein was detected in dystrophic muscles as early as 15 days ex ovo and occurred throughout development up to six months ex ovo. Although the implication of the dystrophy-associated appearance of the 30 kDa protein in the affected muscle is not clear at present, it would be of particular interest to elucidate the biochemical functions of the 30 kDa protein in the affected muscle (pectoralis superficialis muscle) of genetically dystrophic chicken.     

Gene expression pattern of glucose transporters in the skeletal muscles of newly hatched chicks

The gene expression pattern of the glucose transporters (GLUT1, GLUT3, GLUT8, and GLUT12) among pectoralis major and minor, biceps femoris, and sartorius muscles from newly hatched chicks was examined. GLUT1 mRNA level was higher in pectoralis major muscle than in the other muscles. Phosphorylated AKT level was also high in the same muscle, suggesting a relationship between AKT and GLUT1 expression.     

Avian muscular dystrophy: Thyroidal influence on pectoralis muscle growth and glucose-6-phosphate dehydrogenase activity

The pectoralis muscles of dystrophic chickens (line 413) were hypertrophic on the basis of fresh weight and fat-free dry weight. They also had greater DNA content and greater glucose-6-phosphate dehydrogenase (G6PD) and 6-phosphogluconate dehydrogenase (6PGD) activities. Of the parameters measured, the largest differences between pectoralis muscles from dystrophic and normal (line 412) chickens were for DNA content and G6PD activity. These parameters were 4.3- and 6.7-fold, respectively, the values for control pectoralis at 5 wk of age. The average number of nuclei per unit length of isolated muscle fiber was also greater (approximately 3-fold) for the dystrophic pectoralis. Body weight and pectoralis fresh weight, fat-free dry weight, DNA content, G6PD activity and 6PGD activity were reduced significantly in propylthiouracil (PTU)-treated normal and dystrophic chickens. Moreover, the effects of PTU were more pronounced in the dystrophic strain. Thyroid deprivation significantly improved the righting ability of the dystrophic chickens, in addition to its influence on muscle hypertrophy and body growth. Thyroxine (T₄) replacement reversed the PTU effects in both strains. Of all the variables measured, total G6PD activity was the most affected by PTU treatment of dystrophic chickens and was only 16% of the control dystrophic value.In addition to the effects of thyroid deprivation on the expression of avian muscular dystrophy, we observed significant differences in thyroid-related variables in the two strains. The average thyroid weight at 4 wk and serum triiodothyronine level at 5 wk for dystrophic chickens were 65 and 76%, respectively, of the normal values. The results that we report here indicate that altered thyroid function affects the expression of avian muscular dystrophy.     

Myosin heavy chain in avian muscular dystrophy corresponds to the neonatal isozyme

We have previously demonstrated, based on comparison of homologous amino acid sequences and of two-dimensional CNBr peptide gel patterns, that the myosin heavy chain in pectoralis muscles of Storrs, Connecticut dystrophic chickens is different from that of their normal controls (Huszar, G., Vigue, L., De-Lucia, J. Elzinga, M., and Haines, J. (1985) J. Biol. Chem. 260, 7429-7434). Others have shown, however, that genomic banks and mRNA complements of the control and dystrophic birds are not different. In the present studies, we have examined the hypothesis that the "dystrophic" myosin heavy chain is not a novel gene product, but is a developmental isozyme which is expressed in pectoralis muscles of adult chickens due to the dystrophic process. Two-dimensional maps of myosin heavy chain CNBr peptides were prepared from breast muscles of 17-day in ovo (embryonic), 25-day posthatch (neonatal), and adult birds of the Storrs dystrophic and of two control strains. Also, myosin and actomyosin ATPase enzymatic activities of the various preparations were determined in the pH range of 5.5 to 9.0. Analysis of the peptide maps demonstrates that the embyronic, neonatal, and control adult myosin heavy chain isozymes are distinctly different gene products with only minute variations between the respective developmental isozymes in dystrophic and control muscles. However, the pectoralis myosin heavy chain of adult dystrophic birds, which is a homogeneous isozyme population by amino acid sequences and gel patterns, corresponds to that of the neonatal-type myosin heavy chain. The ATPase properties of the embryonic, neonatal, or adult pectoralis myosins and actomyosins were not different, whether the level of specific activity or the pattern of pH activation is considered. Since the mobility of neonatal chicks (primarily neonatal-type isozymes) is not restricted, the differences in myosin heavy chain structures are part of the syndrome, but not the cause of avian muscular dystrophy.     

Succinic Dehydrogenase Distribution in the Pectoralis Muscle of Several East African Birds

The distribution of succinic dehydrogenase activity was investigated in the pectoralis muscle of thirteen East African birds, representing five Orders. It was found that the pectoralis muscle of the most primitive birds studied (Galliformes) contained all “white” muscle fibres whereas the more advanced birds (Passeriformes) had all “red” muscle fibres. Intermediate Orders had mostly a mixture of red and white muscle fibres. There also appeared to be a direct relationship between body size and average muscle fibre size. However, it was concluded that the most important factor in relation to the muscle structure is the bird's mode of flight. The relationship with the degree of evolution and body size only held true in so far as the birds which had developed the facility for sustained flight, by increasing their red muscle fibre content, were also smaller in size and constituted the more “evolved” Orders of birds. In support of this it was noted that migratory birds (i.e. engaging in sustained flight) from more primitive Orders also had a high red muscle fibre content in their pectoralis muscles.     

Gliding flight in the American Kestrel (Falco sparverius): An electromyographic study

Electromyographic (EMG) activity was studied in American Kestrels (Falco sparverius) gliding in a windtunnel tilted to 8 degrees below the horizontal. Muscle activity was observed in Mm. biceps brachii, triceps humeralis, supracoracoideus, and pectoralis, and was absent in M. deltoideus major and M. thoracobrachialis (region of M. pectoralis). These active muscles are believed to function in holding the wing protracted and extended during gliding flight. Quantification of the EMG signals showed a lower level of activity during gliding than during flapping flight, supporting the idea that gliding is a metabolically less expensive form of locomotion than flapping flight. Comparison with the pectoralis musculature of specialized gliding and soaring birds suggests that the deep layer of the pectoralis is indeed used during gliding flight and that the slow tonic fibers found in soaring birds such as vultures represents a specialization for endurant gliding. It is hypothesized that these slow fibers should be present in the wing muscles that these birds use for wing protraction and extension, in addition to the deep layer of the pectoralis. © 1993 Wiley-Liss, Inc.     

Preliminary electromyographical analysis of brachiation in gibbon and spider monkey

In order to refine the concept of brachiation as a locomotor mode and to examine the complex relationship between locomotor behavior and muscle morphology, we have undertaken a telemetered electromyographic (EMG) analysis of muscle recruitment in brachiating gibbons (Hylobates lar) and spider monkeys (Ateles belzebuth andAteles fusciceps) Electrical activity patterns were determined for both support and swing phases in the following muscles: cranial pectoralis major, caudal pectoralis major, middle deltoideus, short head of biceps brachii, flexor digitorum superficialis, latissimus dorsi, and dorsoepitrochlearis. Our experimental findings reinforce earlier behavioral observations that brachiation is not a discrete, stereotyped locomotor activity. EMG patterns differed most between gibbon and spider monkey in those muscles that exhibit markedly disparate morphologies in the two genera-pectoralis major (both portions) and the short head of biceps brachii. Additional recruitment differences appear related to consistent species-specific differences in the timing and mechanics of both support and swing phases, and probably to the role of the prehensile tail as a fail-safe mechanism in the spider monkey.     

Oxidative Stress and Metabolic Perturbations in Wooden Breast Disorder in Chickens

This study was conducted to characterize metabolic features of the breast muscle (pectoralis major) in chickens affected with the Wooden Breast myopathy. Live birds from two purebred chicken lines and one crossbred commercial broiler population were clinically examined by manual palpation of the breast muscle (pectoralis major) at 47–48 days of age. Metabolite abundance was determined by gas chromatography/mass spectrometry (GC/MS) and liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) using breast muscle tissue samples from 16 affected and 16 unaffected chickens. Muscle glycogen content was also quantified in breast muscle tissue samples from affected and unaffected chickens. In total, levels of 140 biochemicals were significantly different (FDR < 0.1 and fold-change A/U > 1.3 or < 0.77) between affected and unaffected chickens. Glycogen content measurements were considerably lower (1.7-fold) in samples taken from Wooden Breast affected birds when compared with samples from unaffected birds. Affected tissues exhibited biomarkers related to increased oxidative stress, elevated protein levels, muscle degradation, and altered glucose utilization. Affected muscle also showed elevated levels of hypoxanthine, xanthine, and urate molecules, the generation of which can contribute to altered redox homeostasis. In conclusion, our findings show that Wooden Breast affected tissues possess a unique metabolic signature. This unique profile may identify candidate biomarkers for diagnostic utilization and provide mechanistic insight into altered biochemical processes contributing to tissue hardening associated with the Wooden Breast myopathy in commercial chickens.     

Blood flow in skeletal muscles of chicken in the embryonic and early postembryonic periods

In chicken Leghorn, blood flow volume speed in pectoralis and gastrocnemius muscles was measured on 15 and 19 day-old embryos and at the 1st and the 10th days alter hatching. It was revealed that in the last quarter of embryogenesis BF in muscles did not vary remaining in both muscles in identical limits. Similar BF parameters in pectoralis and gastrocnemius muscles and their age-dependent dynamics were observed at embryos with the detained development (with the body weight 2-fold less than the norm). After hatching, the blood flow in both muscles was grown, on the average, 2.4-fold and remained high by the 10th day, a little decreasing in the pectoralis muscle. It was shown, that increase of a muscular blood flow after hatching was accompanied by different changes of anatomic lumen of the arteries addressed in pectoralis and gastrocnemius muscles: in the former it decreased, in the latter--increased.     

Relative intensity of muscular contraction during shivering.

The intensity of cold-induced shivering, quantified by surface electromyography (EMG) and then expressed as a function of the maximal myoelectrical activity (integrated EMG) obtained during a maximum voluntary contraction (MVC), was examined in this study in individuals classified by body fat. In addition, the relationship between shivering and metabolic rate (MR) and the relative contribution of various muscle groups to total heat production were studied. Ten seminude male volunteers, 5 LEAN (less than 11% body fat) and 5 NORM (greater than 15% body fat) were exposed to 10 degrees C air for 2 h. EMG of six muscle groups (pectoralis major, rectus abdominis, rectus femoris, gastrocnemius, biceps brachii, and brachioradialis) was measured and compared with the EMG of each muscle's MVC. A whole body index of shivering, determined from the mass-weighted intensity of shivering of each muscle group, was correlated with MR. After the initial few minutes of exposure, only the pectoralis major, rectus femoris, and biceps brachii continued to increase their intensity of shivering. Shivering intensity was higher in the central muscles, ranging from 5 to 16% of MVC compared with that in the peripheral muscles, which ranged from 1 to 4% of MVC. Shivering intensities were similar in the peripheral muscles for the LEAN and NORM groups, whereas differences occurred in the trunk muscles for the pectoralis major and rectus abdominis. The whole body index of shivering correlated significantly with each individual's increase in MR (r = 0.63-0.97).(ABSTRACT TRUNCATED AT 250 WORDS)     

Relationships between mitochondrial content and glycogen distribution in porcine muscle fibres.

Serial sections of longissimus dorsi and rectus femoris muscles from 15 Yorkshire breed pigs (live weights 24-46 and 49-139 kg) were stained for glycogen (PAS) and a mitochondrial enzyme (NAD tetrazolium reductase). Muscle fibres with a low mitochondrial content in both muscles were more frequently PAS-positive than fibres with a high or intermediate mitochondrial content. However, some pigs had all their muscle fibres PAS-positive while one pig with a high post-mortem muscle pH had all rectus femoris fibres PAS-negative. Relative to lighter weight pigs, longissimus dorsi muscles of heavy pigs tended to have less fibres with a high mitochondrial content and less fibres with a positive PAS reaction. Compared to longissimus dorsi muscles, rectus femoris muscles had more fibres with a high mitochondrial content and less with a positive PAS reaction. All fibres in both muscles became PAS-negative with an accompanying decrease in pH by 24 hr post-mortem. Fibres from longissimus dorsi muscles frequently had PAS-positive sarcoplasmic cores between their myofibrils. Heavy pigs tended to have larger cores (up to a mean maximum diameter of 13.4 mum), more fibres with cores, and more cores per fibre. The pigs involved exhibited no other ante- or post-mortem muscle abnormalities.     

Polymorphism in the Prolactin Promoter and Its Association with Growth Traits in Chickens

The pituitary hormone prolactin has a wide variety of functions involving growth, behavioral, and ovarian activities in chickens. The objectives of the present study were to identify polymorphisms in the prolactin promoter and estimate their effects on growth traits in White Leghorn chickens. Among 28 haplotypes found, the h1 haplotype was predominant. Body weight at 16 and 64 weeks and age at sexual maturity were significantly associated with haplotype combinations (P < 0.05). The h1/h1 haplogroup showed the highest body weight at 16 weeks of age, and h1/h7 was the highest at 64 weeks. The lowest age at sexual maturity was found in birds with the h1/h6 haplotype combination, and mRNA expression of prolactin was lowest in h1/h4 birds and highest in h1/h5 birds. The prolactin promoter was highly polymorphic and had significant associations with growth traits in White Leghorn chickens.     

Fibre types in primary ‘flight’ muscles of the African Penguin (Spheniscus demersus)

The African penguin (Spheniscus demersus) is an endangered seabird that resides on the temperate southern coast of Africa. Like all penguins it is flightless, instead using its specialized wings for underwater locomotion termed ‘aquatic flight’. While musculature and locomotion of the large Antarctic penguins have been well studied, smaller penguins show different biochemical and behavioural adaptations to their habitats. We used histochemical and immunohistochemical methods to characterize fibre type composition of the African penguin primary flight muscles, the pectoralis and supracoracoideus. We hypothesized the pectoralis would contain predominantly fast oxidative–glycolytic (FOG) fibres, with mainly aerobic subtypes. As the supracoracoideus and pectoralis both power thrust, we further hypothesized these muscles would have a similar fibre type complement. Our results supported these hypotheses, also showing an unexpected slow fibre population in the deep parts of pectoralis and supracoracoideus. The latissimus dorsi was also examined as it may contribute to thrust generation during aquatic flight, and in other avian species typically contains definitive fibre types. Unique among birds studied to date, the African penguin anterior latissimus dorsi was found to consist mainly of fast fibres. This study shows the African penguin has specialized flight musculature distinct from other birds, including large Antarctic penguins.     

A survey of tissue-specific isozyme expressions during chicken ontogeny

The ontogenetic trends in the expression of 25 isozymes in liver, gizzard, heart, and pectoralis muscle of White Leghorn chickens were examined using starch gel electrophoresis. Little change in expression during development was evident in liver S-AAT-A, GPI-A, S-ICDH-A, S-MDH-A and M-MDH-A, in gizzard S-ACON-A, ADH-A, GPI-A, HK-1, HK-3, ME-A PEP-1, and PGM-A, in heart ADH-A, HK-1, HK-3, ME-A, PEP-2, PGM-A, and LDH-A, in pectoralis M-ACON-A, S-ACON-A, ADH-A, HK-1, HK-3, ME-A, PEP-2, and PGM-A, and in liver, gizzard, and heart M-ACON-A, ALD-A, CK-A, G3PDH-A, HK-1, and PGDH-A. Increasing levels of activity were demonstrated in liver ADH-A, ME-A, and PEP-2, in heart M-MDH-A, S-ICDH-A, M-ICDH, and M-AAT-A, and in pectoralis LDH-A, LDH-B, G3PDH-3, ALD-A, CK-A, HK-2, and PGM-B. There was a decrease in the activity of HK-1 in liver and in PEP-1 and PGDH-A in pectoralis muscle throughout development. While CK-C is active in the embryonic pectoralis, CK-A is restricted to later developmental stages. Isozyme expressions in regions of the pectoralis containing fast and slow muscle fibers in 7-month-posthatch individuals were noted and found to be identical. The results underscore the need to use similar developmental stages and tissue samples in comparative electrophoretic studies of birds.This study was supported by Natural Sciences and Engineering Research Council of Canada Grant A9866 to J.P.B.     

A combined histochemical and biochemical study of myofibrillar ATPase in pectoral, leg and cardiac muscle of several species of bird

Synopsis Frozen sections of the pectoral, gastrocnemius and cardiac muscles from seven different species of birds were stained for myofibrillar ATPase and for succinic dehydrogenase. Several methods of myofibrillar ATPase were used including different pre-incubation treatments. Myofibrillar ATPases were also measured biochemically and the pH profile of the activity was compared with the histochemical staining following pre-incubation at different pH. Myofibrils from the different muscles were also subjected to sodium dodecyl sulphate acrylamide gel electrophoresis in order to separate the low molecular weight components of myosin. The results demonstrated that histochemical methods can be applied, with a reasonable degree of confidence, to classifying fibres in avian muscles although the classification used for mammalian muscles needs to be modified. They also showed that avian muscles, particularly the pectoralis, varies considerably between species and their mode of locomotion.     

Enzyme activity in livers from chickens (Gallus domesticus) experimentally infected with the digenetic trematode, Amphimerus elongatus (Trematoda: Opisthorchiidae)

Day old Leghorn chickens were infected with the digenetic trematode Amphimerus elongatus. After different periods of growth, birds were sacrificed and liver enzyme activity determined for six enzymes. Specific activities of adenylate kinase, lactate dehydrogenase, malate dehydrogenase and phosphoglucomutase were significantly lower in infected chickens than in controls. Creatine kinase and glucosephosphate isomerase activities were unaffected by the parasite.     

Myostatin regulation during skeletal muscle regeneration

Myostatin, a member of the TGF-beta superfamily, is a key negative regulator of skeletal muscle growth. The role of myostatin during skeletal muscle regeneration has not previously been reported. In the present studies, normal Sprague-Dawley and growth hormone (GH)-deficient (dw/dw) rats were administered the myotoxin, notexin, in the right M. biceps femoris on day 0. The dw/dw rats then received either saline or human-N-methionyl GH (200microg/100g body weight/day) during the ensuing regeneration. Normal and dw/dw M. biceps femoris were dissected on days 1, 2, 3, 5, 9 and 13, formalin-fixed, then immunostained for myostatin protein. Immunostaining for myostatin revealed high levels of protein within necrotic fibres and connective tissue of normal and dw/dw damaged muscles. Regenerating myotubes contained no myostatin at the time of fusion (peak fusion on day 5), and only low levels of myostatin were observed during subsequent myotube enlargement. Fibres which survived assault by notexin (survivor fibres) contained moderate to high myostatin immunostaining initially. The levels in both normal and dw/dw rat survivor fibres decreased on days 2-3, then increased on days 9-13. In dw/dw rats, there was no observed effect of GH administration on the levels of myostatin protein in damaged muscle. The low level of myostatin observed in regenerating myotubes in these studies suggests a negative regulatory role for myostatin in muscle regeneration.     

Effects of the sex-linked dwarf gene (dw) on the expression of the muscular dystrophy gene (am) in chicken.

The sex-linked dwarf gene (dw) was introduced into companion muscular dystrophic (am) and nondystrophic (Am+) New Hampshire chicken lines to investigate influences of the dwarf gene on breast muscle weights, muscle fiber area, and the histological expression of muscular dystrophy. Dystrophic and nondystrophic chickens within dwarf or nondwarf genotypes were similar in body and carcass weights. Pectoralis and supracoracoideus muscle weights (as a percentage of adjusted carcass weight) were similar in nondystrophic dwarf and nondwarf males and females. In addition, pectoralis weight was similar in dystrophic dwarf males and dystrophic nondwarf males and females. However, pectoralis weight was significantly smaller in dystrophic dwarf females than in dystrophic nondwarf females, whereas supracoracoideus weight was significantly larger in dystrophic dwarf males than in dystrophic nondwarf males. Supracoracoideus weight was similar in dystrophic dwarf males and females and dystrophic nondwarf females. Pectoralis muscle fiber area was influenced by sex and by dwarf and dystrophy genotype. Muscle fiber area was larger in females than in males, smaller in dwarfs than in nondwarfs, and smaller in dystrophic than in nondystrophic muscles. Muscle fiber degeneration and adipose infiltration was more extensive in dystrophic than in nondystrophic females and males, and it was more advanced in dwarfs than in nondwarfs. Excessive acetylcholinesterase staining patterns were characteristic of dystrophic muscle in both dwarf and nondwarf genotypes. Nondystrophic and dystrophic dwarf male and female chickens are comparable substitutes for nondwarfs as biomedical models with respect to pectoralis histology, acetylcholinesterase staining pattern, and pectoralis muscle hypertrophy.