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At least 145 records · Page 8Linked to original sources
PubMed1999

Tenderness, moisture loss and post-mortem metabolism of broiler Pectoralis muscle from electrically stimulated and air chilled carcases.

1. This study was to evaluate the effects of post-mortem electrical stimulation (ES) on carcase moisture loss and on tenderness, R-value and pH of breast fillets following air chilling. 2. In each of 4 replications, 8 birds were electrically stimulated and 12 birds were controls. The ES birds were stimulated at the head in a 1% saline bath (450 V, 0.45 A, 2 s on/1 s off for 7 pulses). After evisceration the carcases were air chilled in a cooler at 1 to 2 degrees C with an average relative humidity of 91% and an air speed of 44 m/min. 3. Breast fillets were harvested at 2 and 4 h postmortem from both ES and control carcases and also at 8 h postmortem from control carcases to determine moisture loss pH and R-value. 4. Although there was no significant effect of ES on shear value at 2 h postmortem, the ES fillets had a lower shear value mean than the control fillets at 4 h postmortem. There was no significant difference between the shear value means of the ES 4 h fillets and the control 8 h fillets. 5. ES accelerated the normal post-mortem decline in pH at both 2 and 4 h postmortem. 6. The R-value means for the control and ES samples were similar 2 h but the R-value mean of the ES samples was greater than the control at 4 h postmortem. 7. The results suggest that, when followed by air chilling, ES accelerates postmortem metabolism, reduces ageing by up to 50%, and has no effect upon evaporative moisture loss.

Animals↗
PubMedDate not supplied

Normal and dystrophic embryonic chicken pectoralis muscle cultures: II. Ultrastructural comparison.

Ultrastructural comparison was made between dystrophic and normal chicken breast muscle cells which had been isolated from 12-day-old embryos and cultured for up to 14 days. All electron microscopic examinations were conducted in the absence of any knowledge as to the dystrophic or normal origin of the cells, or the day on which the cells had been harvested from culture. The same blind procedures were applied to attempts to reconstruct from electron micrographs the correct sequence of days for a particular experiment and to identify the origin of the cells as normal or dystrophic. No consistent differences between normal and dystrophic cells were apparent either in extent of differentiation, such as the formation of mature sarcomeres, or in degenerative properties, such as disintegrating mitochondria, lipid aggregations, or extracellular debris. In light of metabolic and developmental differences in these cultures, the absence of ultrastructural differences was attributed in part to the presence of cells with widely different degrees of integrity, differentiation, and degeneration in both normal and dystrophic cultures.

Animals↗
PubMedDate not supplied

Normal and dystrophic embryonic chicken pectoralis muscle cultures: III. Viral infection of normal cell cultures.

Twelve-day normal and dystrophic chick embryo breast muscle cells were cultured for up to 14 days, using normal embryo extract in the culture medium. Fluorodeoxyuridine was added on day 3 to suppress fibroblast overgrowth. Three of 6 experiments with normal cells were severely infected with avian leucosis/sarcoma (ALS) virus particles. The findings appear to lend support to the suggestion that the ALS virus is a mitochondriophage. Infected cultures demonstrated a depressed rate of total protein synthesis as reflected by incorporation of [3H]leucine. Extractable protein and total protein content were also depressed within several days after ALS particles were identified. These findings reinforce caution in acceptance of the common assumption that viral infections are an unavoidable and metabolically benign component of muscle cell cultures.

Alpharetrovirus↗
PubMed1987

Isolation and clonal analysis of satellite cells from chicken pectoralis muscle.

Satellite cells, liberated from the breast muscle of young adult chickens by sequential treatment with collagenase and trypsin, were fractionated by Percoll density centrifugation to remove myofibril fragments and cell debris which otherwise heavily contaminate the preparation. This procedure allowed direct measurements of cell yields (1.5-4 X 10(5) cells/g tissue), plating efficiencies (27-40%) and identification of single cells in culture. In mass cultures, satellite cells gave rise to myotubes on the fifth day, and the progeny of these cells were sequentially passaged several times without losing myogenic traits. In clonal studies, over 90% of the satellite cells gave rise to large clones of which more than 99% were myogenic as demonstrated by the appearance of myotubes. The results obtained with satellite cells differ from observations made using embryonic muscle cell preparation from chicks. In the embryonic system massive formation of myotubes was observed following the third day of culture; sequential subculturing led to overgrowth of fibroblast-like cells following the first passage; and cells gave rise to both small myogenic clones (up to 16 terminally differentiated cells per clone) and non-myogenic clones in addition to large myogenic clones. We conclude that the isolated satellite cells represent a homogeneous cell population and reside in a stem cell compartment.

Animals↗
PubMed2002

Fate of plasmid DNA encoding infectious bursal disease virus VP2 capsid protein gene after injection into the pectoralis muscle of the chicken.

The objective of this study was to determine whether recombinant plasmid DNA injected intramuscularly into chickens expressed the gene of interest in vivo and could be subsequently detected in primary and secondary lymphoid tissues with polymerase chain reaction (PCR). The VP2 capsid protein gene of the standard challenge strain (STC) of infectious bursal disease virus (IBDV) was cloned into a eukaryotic plasmid, and purified DNA was prepared. Fourteen 2-wk-old chickens were injected in the pectoral musculature with 500 microg of plasmid DNA dissolved in sterile PBS. Seven chickens were similarly injected with PBS alone. Pectoral muscle, thymus, spleen, bursa of Fabricius, and cecal tonsils were collected at 12, 24, 36, 48, 72, 96, and 168 h postinjection for detection of protein expression (in muscle) and to extract total DNA for PCR amplification of the VP2 capsid gene. Expression of VP2 was demonstrated in muscle tissue at 12 and 24 h postinjection by using an indirect immunofluorescence assay. PCR amplification with primers specific for the VP2 gene showed that the DNA was present in the thymus, spleen, and bursa of Fabricius but not in cecal tonsils. These results demonstrate that plasmid DNA injected directly into the pectoral muscle of chickens is transcribed and translated at the injection site and promptly distributed to primary and secondary lymphoid tissues.

Animals↗
PubMed1991

Myosin isoform expression in skeletal muscles of turkeys at various ages.

The appearance of myosin isoforms in skeletal muscles of turkey embryos, poults, and toms was studied, using monoclonal antibodies raised against myosin isoforms in chicken fast-twitch muscle (Pectoralis). The myosin extract was prepared by repeated salt extraction-precipitation. The reactivity of monoclonal antibodies with turkey myosin isoforms was tested by an enzyme linked immunosorbent assay using alkaline phosphatase-conjugated antibody and detection by color development with p-nitrophenyl phosphate. Detection was also effected by protein slot blotting using peroxidase-conjugated antibody and color development with 3,3'-diaminobenzidine tetrahydrochloride. The monoclonal antibody AB8 was found to be specific for the adult myosin isoform, present in Pectoralis muscle of 14-day-old and adult turkeys and adult chickens. Subsequent peptide mapping also indicated that the adult myosin isoform of turkey Pectoralis muscle was nearly identical to the adult isoform from chickens. The monoclonal antibody 2E9 reacted with the myosin extract only from poults at ages of 7 days and 14 days posthatch, indicating that 2E9 is specific for the neonatal myosin isoform. The reactivity of 2E9 was noted with the muscle of the mixed fiber type (the thigh muscle group) as well as with the fast-twitch muscle (Pectoralis). Monoclonal antibodies EB 165 and AG6 were found to react with the myosin extract from all ages tested. Based on the reactivity with monoclonal antibodies, it was concluded that myosin in turkey muscles existed as at least three discrete isoforms that were expressed sequentially in the course of muscle development.

Age Factors↗