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ABSTRACT: Our previous transcriptional profiling study using a turkey skeletal muscle-specific oligonucleotide microarray revealed over 3,000 genes that were differentially expressed at 3 critical stages of muscle development: 18 d embryonic, 1 d posthatch, and 16 wk of age. The genes versican, matrix Gla protein (MGP), and death-associated protein (DAP) were selected to study for their potential effects on muscle satellite cell proliferation and differentiation, as their functions in other tissues are suggestive of possible key roles in the regulation of myogenesis and they are differentially expressed throughout muscle development in the turkey. Using small interfering RNA to knockdown the expression of these genes during proliferation and differentiation, each of the genes was found to differentially affect proliferation and differentiation. Versican and MGP predominantly affected proliferation with line effects, but later stages of differentiation were affected by the knockdown of versican and MGP. The underexpression of DAP inhibited myotube formation, which is a necessary stage in the development of muscle fibers. Without myotube development, muscle fiber formation will be inhibited or abolished. This is the first report that these genes with no previously documented functions with regard to muscle development play a critical role in muscle cell proliferation and differentiation.
Poultry Science 08/2012; 91(8):1964-73. · 1.73 Impact Factor
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ABSTRACT: Aberrant postmortem Ca(2+)-regulation in the early postmortem period is associated with the occurrence of inferior meat quality in turkeys, described as pale, soft, and exudative (PSE). The objective of the current study was to quantify expression of 4 candidate genes responsible for maintaining Ca(2+) homeostasis in turkey skeletal muscle as a function of heat stress: α and β ryanodine receptors (RYR; Ca(2+)-release channels), the sarco/endoplasmic reticulum Ca(2+)-ATPase 1 (SERCA1), and the sarcoplasmic reticulum, Ca(2+)-storage protein calsequestrin (CASQ1). Two genetic lines of turkeys were used: a growth-selected commercial line and a randombred control line. Market-age birds were subjected to one of 5 heat stress treatments: no heat, 1 d, 3 d, 5 d, or 7 d of heat followed by 7 d of ambient temperature. Breast muscle samples were harvested and classified as normal or PSE using the meat quality parameters percentage of marinade uptake and percentage of cook loss. These parameters differed significantly by line, heat stress treatment, and meat quality status. Expression of candidate genes was measured using TaqMan quantitative PCR. Heat treatment was associated with significantly enhanced expression of αRYR, βRYR, and CASQ1 in normal muscle from both lines. Conversely, mRNA abundance of these genes was reduced in PSE muscle from both lines and recovered or increased by 7 d + 7 d of rest. Genetic line differences were observed at several time points. Expression of SERCA1 in both normal and PSE samples from both lines was unchanged or trended downward with heat stress. Taken together, genetic line and heat-stress treatment affected the expression of important Ca(2+)-regulating genes in association with meat quality status. The data suggest that birds whose meat leads to PSE may fail to respond to heat stress appropriately due to a delay in the upregulation of the important calcium-regulating genes: αRYR, βRYR, and CASQ1.
Poultry Science 06/2012; 91(6):1418-24. · 1.73 Impact Factor
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ABSTRACT: Skeletal muscle is composed of metabolically heterogeneous myofibres that exhibit high plasticity at both the morphological and transcriptional levels. The objective of this study was to employ microarray analysis to elucidate the differential gene expression between the tonic-'red' anterior latissimus dorsi (ALD) muscle, the phasic-'white' posterior latissimus dorsi (PLD) and 'mixed'-phenotype biceps femoris (BF) in 1-week-and 19-week-old male turkeys. A total of 170 differentially expressed genes were identified in the muscle samples analysed (P < 0.05). Gene GO analysis software was utilized to identify top gene networks and metabolic pathways involving differentially expressed genes. Quantitative real-time PCR for selected genes (BAT2D, CLU, EGFR and LEPROT) was utilized to validate the microarray data. The largest differences were observed between ALD and PLD muscles, in which 32 genes were over-expressed and 82 genes were under-expressed in ALD1-PLD1 comparison, and 70 genes were over-expressed and 70 under-expressed in ALD19-PLD19 comparison. The largest number of genes over-expressed in ALD muscles, as compared to other muscles, code for extracellular matrix proteins such as dystroglycan and collagen. The gene analysis revealed that phenotypically 'red' BF muscle has high expression of glycolytic genes usually associated with the 'white' muscle phenotype. Muscle-specific differences were observed in expression levels of genes coding for proteins involved in mRNA processing and translation regulation, proteosomal degradation, apoptosis and insulin resistance. The current findings may have large implications in muscle-type-related disorders and improvement of muscle quality in agricultural species.
Animal Genetics 06/2012; 43(3):298-308. · 2.40 Impact Factor
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ABSTRACT: Consumer demand for lean, inexpensive meat products has driven the domestic turkey (Meleagris gallopavo) industry to unprecedented production; however, this has coincided with an increase in growth-induced myopathies and meat quality defects. With the aim of developing a new tool for the study of turkey growth and development at the muscle transcriptome level, a 6K oligonucleotide microarray was constructed, the Turkey Skeletal Muscle Long Oligo (TSKMLO) microarray. Skeletal muscle samples were collected at three critical stages in muscle development: 18-day embryo (hyperplasia), 1-day post-hatch (hypertrophy), and 16-week (market age) from two genetic lines of turkeys: RBC2, a line maintained without selection pressure, and F, a line selected from the RBC2 line for increased 16-week body weight. Oligonucleotides were designed from sequences obtained from skeletal muscle cDNA libraries from the three developmental stages. Several unique controls, including mismatch and distance controls and scrambled sequences, were designed for 30 genes. Quality control hybridizations were completed, confirming the validity and repeatability of the array. Control features were evaluated across two larger experiments comparing developmental stage within genetic line or genetic line within each developmental stage, totaling 70 arrays. Mismatch and scrambled sequences appeared to be useful controls of specific hybridization for most genes. In addition, quantitative real-time RT-PCR confirmed microarray results. This creation and assessment of the TSKMLO array provides a valuable community resource for the study of gene expression changes related to turkey muscle growth and development.
Animal Genetics 02/2011; 42(1):75-82. · 2.40 Impact Factor
