The association of genetic variations in the promoter region of myostatin gene with growth traits in Duroc pigs.

Average daily gain (ADG) and feed efficiency (FE) are important factors for assessing productivity in farm animals. Myostatin (MSTN), previously called GDF8, is a member of transforming growth factor ß (TGFß) superfamily. It is a negative regulator for both embryonic development and adult homeostasis of skeletal muscle. In this study, the genotypes of MSTN g.435G > A and g.447A > G SNPs in Duroc pigs were determined. The 435GG/447AA individually had significantly higher ADG (P < 0.01), body weight at 70 d (P < 0.05) and 150 d (P < 0.01), and a lower age at 110 kg (P < 0.01) than 435AA/447GG individuals. Dose dependent genetic additive effects were found for the negative effects of the 435A/447 G allele for ADG and body weight on 70 d and 150 d. The 435A/447 G allele also increased the age at 110 kg about 1.47 and 4.53% for 1 and 2 copies, respectively. The MSTN 435 G/447A allele increased the age at 110 kg about 1.41 and 4.47% for 1 and 2 copies, respectively. Overall, the two mutated MSTN 435A/447G allele had negative effects on ADG (P < 0.01), body weight at 70 d (P < 0.05), and 150 d (P < 0.001) and increased the age at 110 kg (P < 0.001). The present study provided evidence that MSTN g.435G > A and g.447A > G affected growth in Duroc pigs. The effects of the mutated alleles were additive with the maximal effects resulting from two copies of the wild-type allele. Selection for the 435 G/447A allele is expected to increase ADG, body weight and decrease the age at 110 kg in Duroc pigs and might be used in porcine breeding programs.

In vitro culture period but not the passage number influences the capacity of chimera production of inner cell mass and its deriving cells from porcine embryos.

Mammalian embryonic stem (ES) cells are pluripotent cells derived from the inner cell mass (ICM) of the blastocyst. These cells are able to proliferate continuously without differentiation in vitro under suitable conditions. Their capacity of pluripotency in differentiation will be resumed when they are reintroduced into host embryos, when they will contribute to the embryonic development to form chimeric individuals. Manipulation of ES cells has been mainly established from studies in the mouse, and is powerful in the production of transgenic animals. Porcine ICM-derived cell lines possess the same cellular morphology and in vitro behavior as those of murine ES cells, but have lower efficiency in chimera formation when reintroduced into host embryos. This study was to determine the influences of passage number and the duration of in vitro culture on the capacity of porcine ICM-derived cells in the generation of chimeric embryos. The results showed that when passage number of porcine ICM-derived cells was less than 15, there were no detrimental effects on its integration ability. Extending the culture time up to 6 days in each passage of porcine ICM-derived cells impaired its integration capacity into the host blastocyst. Porcine ICM-derived cells cultured for more than 4 days in each passage should not be used for blastocyst injection if high efficiency of chimera production is to be achieved.