Detection of SNPs in the TBC1D1 gene and their association with carcass traits in chicken.

TBC1D1 plays an important role in numerous fundamental physiological processes including muscle metabolism, regulation of whole body energy homeostasis and lipid metabolism. The objective of the present study was to identify single nucleotide polymorphisms (SNPs) in chicken TBC1D1 using 128 Erlang mountainous chickens and to determine if these SNPs are associated with carcass traits. The approach consisted of sequencing TBC1D1 using a panel of DNA from different individuals, revealing twenty-two SNPs. Among these SNPs, two polymorphisms (g.69307744C>T and g.69307608T>G) of block 1, four polymorphisms (g.69322320C>T, g.69322314G>A, g.69317290A>G and g.69317276T>C) of block 2 and four polymorphisms of block 3 (g.69349746G>A, g.69349736C>G, g.69349727C>T and g.69349694C>T) exhibited a high degree of linkage disequilibrium in all test populations. An association analysis was performed between the twenty-two SNPs and seven performance traits. SNPs g.69307744C>T, g.69340192G>A and g.69355665T>C were demonstrated to have a strong effect on liveweight (BW), carcass weight (CW), semi-eviscerated weight (SEW) and eviscerated weight (EW) and g.69340070C>T polymorphism was related to BW, SEW and BMW in chicken populations. However, for the other SNPs, there were no significant correlations between different genotypes and carcass traits. Meanwhile, haplotype CT-TG of block 1 and combined genotype AG-TT-AC-CT of block 3 were significantly associated with BW, CW, SEW and EW. Overall, our results provide evidence that polymorphisms in TBC1D1 are associated with carcass traits and would be a useful candidate gene in selection programs for improving carcass traits.

Silencing Pax3 by shRNA inhibits the proliferation and differentiation of duck (Anas platyrhynchos) myoblasts.

The Pax3 gene has been proven to play a crucial role in determining myogenic progenitor cell fate during embryonic myogenesis; however, the molecular role of Pax3 in myoblast development during later stages of myogenesis is unknown. We hypothesized that Pax3 would function in myoblast proliferation and differentiation; therefore, we employed three short hairpin RNAs (shRNAs) (shRNA1, shRNA2, and shRNA3) that target Pax3 to characterize the function of Pax3 in duck myoblast development. The mRNA and protein expression levels of Pax3 in duck myoblasts were detected using real-time PCR and Western blotting. Cell proliferation was assessed using the MTT and BrdU assays, while cell differentiation was assayed using immunofluorescence labeling with a MyoG antibody. Additionally, folic acid (FA), which is a rescue tool, was added into the medium of duck myoblasts to indirectly examine the function of Pax3 on duck myoblast proliferation and differentiation. The results revealed that one of the shRNA vectors, shRNA1, could significantly and stably reduce the expression of Pax3 (P < 0.05). Silencing Pax3 by shRNA1 significantly reduced the proliferation and differentiation of duck myoblasts (P < 0.05) due to downregulated expression of myogenic regulator factors. These trends could be rescued by adding FA; and Pax7, a paralog gene of Pax3, was involved in those processes. Overall, Pax3 had a positive function in duck myoblast proliferation and differentiation by modulating the expression of myogenic regulation factors, and shRNA targeting of Pax3 might be a new approach for understanding the function of Pax3 in the development of diverse tissues.

Polymorphisms and expression of the chicken POU1F1 gene associated with carcass traits.

POU1F1 is an essential factor that regulates the development and reproduction of animal. The objective of the current research was to screen for polymorphism, expression of POU1F1 and their association with carcass quality traits. A total of 126 Erlang mountainous chickens from two strains (SD02 and SD03) were employed for testing. Seventeen single nucleotide polymorphisms (SNPs) were detected, but only two SNPs (g.96217999 T > C and g.96219442 C > T) were associated with carcass quality traits. In SD03 chicken, g.96217999 T > C genotypes were significantly associated with body weight (BW), carcass weight (CW), eviscerated weight (EW), and semi-eviscerated weight (SEW; P < 0.05), and was highly significantly associated with breast muscle weight (BMW) and abdominal fat weight (AW; P < 0.01). g.96219442 C > T was significantly associated with BW, EW, SEW (P < 0.05). However, these two SNPs were not significantly associated with any carcass traits in SD02 chicken. Diplotypes showed that in SD03 chicken, the haplotype [C: C] was the most favorable haplotype because it was associated with higher BW, CW, SEW, EW, BMW, and AW (P < 0.05). On the contrary, haplotype [T: T] was associated with lower carcass quality traits (P < 0.01). In addition, qRT-PCR revealed that at 13 weeks, the POU1F1 mRNA expression was significantly higher in breast muscle of cock compared to that of hens (P < 0.05), whereas there was no significant correlation between POU1F1 expression and carcass traits. These results suggested that POU1F1 could be a potential candidate gene for carcass traits in chicken.

In ovo feeding of IGF-1 to ducks influences neonatal skeletal muscle hypertrophy and muscle mass growth upon satellite cell activation.

To investigate reasons for the muscle increase observed when eggs are treated by IGF-1 and whether or not satellite cell activation is specific to different types of myofibers, duck eggs were administrated with IGF-1. After injection, during the neonatal stages, the duck breast muscle and leg muscle were isolated for analysis. The muscle weight, muscle fiber diameter (MFD), cross-sectional area (CSA), the number of myofibers per unit area (MFN) and frequency of satellite cell activation and mitosis at the embryo stage of 27 days (27E) and the postnatal stage of 2 days after hatching (P2D) were determined. In addition, expression of two important myogenic transcription factors MyoD and Myf5 were detected and compared in the two types of muscle tissues. Results indicated that IGF-1 administration increased the duck body weight, MFD, CSA, MFN, and quantity of activated satellite cells and mitotic nuclei in the two types of muscle tissues. The MyoD and Myf5 expressed at a higher level in IGF-1-treated muscle. IGF-1 stimulated muscle weight growth more in the leg muscle than in the breast muscle. These results indicate that in ovo feeding of IGF-1 can stimulate duck growth and, especially, lead to increased muscle hypertrophy. These increases appear to be mainly dependent on the activation of satellite cells, some of which proliferate and fuse to the myofiber, enabling increased muscle mass. IGF-1 can indirectly affect satellite cells by regulating the expression of two important myogenic transcription factors, MyoD and Myf5, which help activate satellite cells.

[Progress in the study on mammalian diacylgycerol acyltransgerase (DGAT) gene and its biological function].

Diacylglycerol acyltransferase (DGAT; EC 2.3.1.20) is a microsomal enzyme that plays a central role in the metabolism of cellular glycerolipids. DGAT catalyzes the final step in triacylglycerol (TAG) biosynthesis by converting diacylgycerol (DAG) and fatty acyl-coenzyme A (CoA) into triacylglycero1. DGAT plays a fundamental role in the metabolism of cellular diacylglycerol and is important in higher eukaryotes for physiologic processes involving triacylglycerol metabolism such as intestinal fat absorption, lipoprotein assembly, adipose tissue formation, and lactation. Therefore, DGAT is not only an key factor for control triglycerides and fatty acids, but also may play a key modulatory role in animal fat deposition.