Expression Profile of Protein Phosphatase 3 Catalytic A Gene(PPP3CA) mRNA in Muscles of Two Duck Breeds (Anas platyrhynchos domestica) and Its Relationship with Myofiber Traits During Early Development
Abstract：Protein phosphatase 3 catalytic A (PPP3CA) is a major isozyme of PPP3C in skeletal muscle and plays an important role in myofiber differentiation. In the present study, expression of PPP3CA mRNA was quantified by absolute quantitative RT-PCR in the pectorale and leg muscle tissues from Jinding ducks and Gaoyou ducks (Anas platyrhynchos domestica) differing in growth rates on days 13, 17, 21, 25, 27 of embryonic development and 7 days post-hatching (PH). The results showed that there was a significant variation with the age of ducks in the PPP3CA mRNA expression profile of the same muscle tissue in 2 duck breeds, but there was no significant breed and sex effect. In both pectoral and leg muscles, the expression peak of PPP3CA mRNA appeared at 13 embryonic day (E13 d) and the PPP3CA mRNA expression level at 7 d PH was very significantly higher than that at E27 d (before hatching) (P＜0.01). In pectoral muscles, the expression of PPP3CA mRNA was firstly declined from E13 d to E21 d, then increased from E21 d to 7 d PH, and the lowest point appeared at E21 d which was very significantly lower than that at other embryonic age or day-old (P＜0.01). In leg muscles, the expression of PPP3CA mRNA was significantly declined from E13 d to E17 d, then significantly increased to E21 d, then decreased gradually to E27 d, and finally increased to 7 d PH; the lowest point appeared at E27 d which was very significantly lower than that at other embryonic ages or day-old (P＜0.01), and the expression level was not significantly different among E17 d, E25 d and 7 d PH (P＞0.05). The correlation analysis showed that varying degrees of linear correlation were found between the expression of PPP3CA mRNA in leg muscles and myofiber types, diameter, cross-sectional area and density the data were detected in former studies in 2 duck breeds; the expression levels of PPP3CA mRNA in pectoral and leg muscles of 2 duck breeds were significantly positively correlated with IGF-Ⅰ mRNA expression which was detected by us in former studies (P＜0.05 or P＜0.01). These results suggested that PPP3 might have potential functions in controlling myofiber phenotype and development during embryonic and early post-hatch development in ducks and there was a synergistic effect between PPP3 and IGF-Ⅰ which might be involved in the regulation of growth development of duck skeletal muscle. The above results provide some valuable clues for understanding the role of PPP3 in the early development of muscles in ducks and a theoretical basis for improving the meat quality in ducks.
