Semester

Summer

Date of Graduation

2001

Document Type

Dissertation

Degree Type

PhD

College

Davis College of Agriculture, Natural Resources and Design

Department

Animal and Nutritional Sciences

Abstract

Reverse-transcription polymerase chain reaction (RT-PCR) was performed to measure myostatin, follistatin, activin-B gene expressions during chicken embryonic development. Strong myostatin expression was found in the early chicken embryos (E 0, E 1) and the developmental expression pattern of myostatin mRNA coincided with the periods of primary and secondary muscle fiber formation. Follistatin transcripts followed a linear expression pattern from E 0 to E 20, while activin-B had a quadratic pattern. The ontogeny of myostatin gene expression was nearly identical in satellite cells isolated from pectoralis major (PM) and biceps femoris (BF) muscles of chicken. Activin-B mRNA level in PM satellite cells was higher than in BF satellite cells at 72 h and 120 h (P < 0.01). IGF-II mRNA level plateaued in PM satellite cells by 48 h after plating (P < 0.05), and remained elevated until 144 h of culture. In ovo administration of rhIGF-I at E 3 shifted myostatin, follistatin, activin-B, and TGF-(32 gene expressions during chicken embryonic development. For example, myostatin mRNA from pectoralis muscles of rhIGF-I injected embryos increased on E 10 (∼2.5 fold) and remained high through E 13, whereas mRNA from control pectoralis muscles increased at E 9 and remained high until E 12. IGF-I, -II and IGF receptor-I mRNA and protein levels were determined in a wide variety of myostatin knockout mice tissues. IGF-I mRNA levels were not different between control and knockout mice tissues, whereas levels for IGF-II were significantly higher in myostatin knockout mice kidney and soleus muscles than that of control mice (P < 0.01). IGF-Receptor-I mRNA levels from control mice heart (P < 0.05) and kidney (P < 0.01) were significantly higher than that of myostatin knockout mice, while levels were lower in control mice pectoralis muscle than that of knockout mice (P < 0.01). The strongly IGF-II positive cells were more common in myostatin knockout mice and were seen in a few foci in control mice, while no consistent differences in IGF-II immunoreactivity were detected between the two groups of mice kidneys.

Download

Share

COinS