Quantitative expression of myogenic regulatory factors MyoD and myogenin in pacu (Piaractus mesopotamicus) skeletal muscle during growth.

UNESP, Institute of Biosciences, Department of Morphology, 18618-000, Botucatu, São Paulo, Brazil.
Micron (Impact Factor: 1.88). 12/2010; 41(8):997-1004. DOI: 10.1016/j.micron.2010.06.012
Source: PubMed

ABSTRACT Skeletal muscle growth is regulated by differential expression of myogenic regulatory factors (MRFs). We evaluated hyperplasia, hypertrophy and quantitative expression of MRFs MyoD and myogenin in 45, 90, 180, and 400 days post-hatching (dph) and adult pacu (Piaractus mesopotamicus) skeletal muscle. Transverse sections of white dorsal muscles were obtained to evaluate hypertrophy and hyperplasia. MyoD and myogenin gene expression was determined by reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR). Pacu skeletal muscle had similar morphology at all stages. The highest and the lowest frequencies of fiber diameters <20 μm were found at the 45 dph and adult stages, respectively. Their frequency was similar in the 90, 180, and 400 dph stages. The highest percentage of >50 μm diameter fibers were found in 180 and 400 dph, and adult fish. Hyperplasia was the main mechanism observed in pacu skeletal muscle growth at 45dph; this declined through 90, 180, and 400 dph and remained low in adult fish; the latter presented hypertrophy as the main mechanism responsible for skeletal muscle growth. The high frequencies of 20-50 μm diameter fibers at 90, 180, and 400 dph can be related to intense hypertrophy. The mRNA levels for MyoD and myogenin were similar in 45, 90, and 400 dph and adult fish, peaking at 180 dph. The high MyoD expression at 180 dph can be related to intense myoblast proliferation and hyperplasia, while high myogenin expression can be related to intense myoblast differentiation and fusion during hypertrophy. MyoD and myogenin expression patterns in adults can respectively be associated with myoblast proliferation and differentiation, which both contribute to hypertrophy. Differential MyoD and myogenin expression in pacu white muscle probably is associated with differences in growth patterns during the stages analyzed. In this study, the 180 dph pacu could represent an interesting phase to investigate suitable strategies in commercial fish production focusing on skeletal muscle growth improvement to raise healthy, fast-growing fish.

  • [Show abstract] [Hide abstract]
    ABSTRACT: Hyperplasia and hypertrophy are two distinct processes of skeletal muscle growth regulated by four myogenic regulatory factors (MRFs, contains MyoD, Myf5, Mrf4 and myogenin (MyoG)) and myostatin (MSTN). In this study, characterization of muscle morphology and satellite cells in juvenile (1-year-old) and adult (2-year-old) Megalobrama amblycephala was described. Compared with 1-year-old M. amblycephala, the diameter scope of epaxial, horizontal septum and hypaxial muscle fibers including red and white muscle in 2-year-old fish exhibited broader with dramatic reduction in frequency distribution of <20 μm diameter, nevertheless observable increase in frequency distribution of >50 μm diameter. Intermyofibrillar (IM) nuclei were also found except numerous subsarcolemmal (SS) nuclei in 2-year-old fish, whereas only SS nuclei were observed in 1-year-old fish. Immunofluorescence results showed that more satellite cells existed in red muscle than white muscle in 1-year-old fish, rather than 2-year-old fish. Moreover, we observed predominant increase in the mRNA levels of MyoD, Myf5, Mrf4, and MSTN during muscle development of fish in 2-year-old fish except MyoG.
    Micron 01/2014; · 1.88 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The objective of this study was to compare the temporal expression of myosin heavy chain (MHC) isoforms, Pax7, and myogenic regulatory factors (MRFs) between heavy weight (HW) and random bred control (RBC) Japanese quail lines during muscle development to better understand the mechanisms leading to increased skeletal muscle mass in the HW quail line selected for a greater body weight at 4 weeks of age separated from RBC quail. Expression of neonatal MHC isoform began at 3 and 7 d post-hatch in RBC and HW quail lines, respectively. In the RBC quail line, adult MHC isoform, as a marker for muscle maturation, was expressed at 28 d post-hatch with sustained expression through 75 d post-hatch, while this protein was detected only at 75 d post-hatch in the HW quail line. Moreover, Pax7 expression continued from embryonic ages to 14 d post-hatch in the HW quail line and to 7 d post-hatch in the RBC quail line. These expression patterns of MHC isoforms and Pax7 in the HW quail line were accompanied by delayed muscle maturation and prolonged growth compared to the RBC quail line. Temporal expressions of the primary MRFs showed that higher expression levels of MyoD and Myf-5 were observed at 9 and 11 d embryo in the HW quail line compared to the RBC quail line (P < 0.05). The HW quail line exhibited approximately two times greater average levels of myogenin expression from 7 to 75 d post-hatch (P < 0.05) than the RBC quail line. Prolonged up-regulation of these primary and secondary MRFs during muscle development is associated with delayed maturation and continued muscle growth, which consequently would permit muscle hypertrophic potentials in the HW quail line compared to the RBC quail line.
    Poultry Science 06/2014; 93:2271. · 1.52 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: This study was designed to extensively characterize the skeletal muscle development in the low weight (LW) quail selected from random bred control (RBC) Japanese quail in order to provide a new avian model of impaired and delayed growth in physically normal animals. The LW line had smaller embryo and body weights than the RBC line in all age groups (P<0.05). During 3 to 42 d post-hatch, the LW line exhibited approximately 60% smaller weight of pectoralis major muscle (PM), mainly resulting from lower fiber numbers compared to the RBC line (P<0.05). During early post-hatch period when myotubes are still actively forming, the LW line showed impaired PM growth with prolonged expression of Pax7 and lower expression levels of MyoD, Myf-5, and myogenin (P<0.05), likely leading to impairment of myogenic differentiation and consequently, reduced muscle fiber formation. Additionally, the LW line had delayed transition of neonatal to adult myosin heavy chain isoform, suggesting delayed muscle maturation. This is further supported by the finding that the LW line continued to grow unlike the RBC line; difference in the percentages of PMW to body weights between both quail lines diminished with increasing age from 42 to 75 d post-hatch. This delayed muscle growth in the LW line is accompanied by higher levels of myogenin expression at 42 d (P<0.05), higher percentage of centered nuclei at 42 d (P<0.01), and greater rate of increase in fiber size between 42 and 75 d post-hatch (P<0.001) compared to the RBC line. Analysis of physiological, morphological, and developmental parameters during muscle development of the LW quail line provided a well-characterized avian model for future identification of the responsible genes and for studying mechanisms of hypoplasia and delayed muscle growth.
    PLoS ONE 01/2014; 9(4):e95932. · 3.53 Impact Factor


Available from