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Muscle Fiber Hyperplasia in Leg Muscle of Transgenic Quail Overexpressing an Alternative Splicing Variant of Myostatin

Chen, Paula Renee

Abstract Details

2016, Master of Science, Ohio State University, Animal Sciences.
Increasing muscle mass is one of the primary goals of the United States poultry industry; however, skeletal muscle development at the molecular level is not fully understood. Myostatin (MSTN) is a well-known negative regulator of muscle growth by inhibiting both myoblast proliferation and differentiation into muscle fibers. Drastic increases in muscle mass have been observed by inhibiting MSTN activity in several species, including mice, cattle, and even humans. Recently, five alternative splicing isoforms of MSTN were discovered in domestic avians. Two of these isoforms, MSTN-A, which encodes the full-length peptide, and MSTN-B, which encodes a truncated peptide devoid of the active MSTN domain, are highly expressed in skeletal muscle. MSTN-B is able to bind and inhibit proteolytic processing of MSTN-A to the mature form, and overexpression of MSTN-B increases myoblast proliferation and myotube differentiation in vitro. Thus, MSTN-B may modulate muscle growth in avians, but further investigation is required to confirm its role in myogenesis. Japanese quail overexpressing MSTN-B in skeletal muscle were generated to elucidate the activity of this isoform in vivo. A 1.2 kb promoter of chicken skeletal muscle alpha actin was used to drive expression of the MSTN-B transgene specifically in skeletal muscle; however, MSTN-B protein was present in thigh muscle but not the pectoralis major muscle in three independent lines. The two lines with the highest MSTN-B expression (A1 and A2) were selected for further study. The growth curves between non-transgenic and transgenic groups in A1 and A2 were not different during a 6-wk growth period beginning at hatch. The pectoralis major muscle weight and heart weight as percentages of body weight were not different between any groups. On the other hand, the right gastrocnemius was a greater percentage of body weight in all transgenic male and female groups in both lines at 21 d posthatch (D21) and 42 d posthatch (D42; p < 0.05) compared to their respective non-transgenic counterparts. During the histological analysis of the left gastrocnemius, fiber number was significantly higher in male and female transgenic quail than non-transgenic quail from A1 and A2 (p < 0.05), but fiber cross-sectional area (CSA) was not different between any of the transgenic and non-transgenic groups. This indicated that the greater gastrocnemius size in MSTN-B transgenic quail was due to increased fiber hyperplasia. Furthermore, Pax-7 expression during embryonic stages was prolonged in A1 and A2 transgenic embryos, allowing for more proliferation of myogenic precursor cells. However, expression of other myogenic regulatory factors was not different between transgenic and non-transgenic groups at any age. Selection of superior poultry breeders by MSTN-B expression may be a useful method of increasing muscle growth for poultry industries.
Kichoon Lee (Advisor)
Macdonald Wick (Committee Member)
Pasha Lyvers-Peffer (Committee Member)
95 p.

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Citations

  • Chen, P. R. (2016). Muscle Fiber Hyperplasia in Leg Muscle of Transgenic Quail Overexpressing an Alternative Splicing Variant of Myostatin [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1462207424

    APA Style (7th edition)

  • Chen, Paula. Muscle Fiber Hyperplasia in Leg Muscle of Transgenic Quail Overexpressing an Alternative Splicing Variant of Myostatin. 2016. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1462207424.

    MLA Style (8th edition)

  • Chen, Paula. "Muscle Fiber Hyperplasia in Leg Muscle of Transgenic Quail Overexpressing an Alternative Splicing Variant of Myostatin." Master's thesis, Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1462207424

    Chicago Manual of Style (17th edition)