Polymorphisms in the promoter region of myostatin gene are associated with carcass traits in pigs.

Higher average daily gain, more lean meat yield and less fat yield of porcine carcass increase selling profits for animal producers. Myostatin (MSTN), previously called GDF8, is a member of transforming growth factor-ß (TGF-ß) superfamily. It is a negative regulator for both embryonic development and adult homeostasis of skeletal muscle. In this study, the genotypes of the previously described SNPs MSTN g.435G>A and g.447A>G SNPs in 66 Duroc pigs, 33 Landrace pigs, 180 Duroc × Landrace (DL) pigs and 155 Duroc × Yorkshire × Landrace (DYL) pigs were determined by Taqman SNP Genotyping Assays. For Duroc and Landrace pigs, MSTN g.435GG/g.447AA individual had greater backfat thickness (p < 0.05) than g.435AA/g.447GG individual, whereas MSTN g.435AA/g.447GG had greater meat (p < 0.05) and meat percentage (p < 0.05) than g.435GA/g.447AG individual. For DL and DYL pigs, the MSTN g.435GG/g.447AA animals were greater in backfat at ultrasound 10th rib (p < 0.05) and carcass 10th rib (p < 0.01) than g.435AA/g.447GG individual. The MSTN g.435AA/g.447GG individual also had higher values than g.435GG/g.447AA for anterior-end meat (p < 0.05), posterior-end meat (p < 0.01), total meat weight (p < 0.01) and meat percentage (p < 0.01). This study confirmed evidence that MSTN g.435G>A and g.447A>G affected carcass traits in pigs. The effects of the mutated alleles were additive with the maximal effects resulting from two copies of the mutated allele. Selection for MSTN g.435A/g.447G allele is expected to increase muscle of limb and total meat production and decrease backfat thickness.

Establishment of the long-term in vitro culture system for chicken primordial germ cells.

The objective of this study was to establish the long-term in vitro culture system for chicken gonadal primordial germ cells (gPGCs). Primitive gonads collected from 5.5-day-old chicken embryos were dissociated and explanted onto plates pre-coated with 0.1% gelatin. Each of the four different conditioned media from proliferating and mitotically inactivated chicken embryonic fibroblast (CEF) cells and murine embryonic fibroblasts (STO cells, CRL-1053, ATCC, USA), respectively, was supplemented with growth factors and used to support the growth of gPGCs. The result showed that all the conditioned media could promote the growth and colony formation of gPGCs in vitro, in particular the medium conditioned by inactivated CEF cells. The gPGC-derived colonies maintained in inactivated CEF cells-conditioned medium up to 281 days were positively stained by periodic acid Schiff reaction and antibodies specific to anti-SSEA-1, SSEA-3, SSEA-4, integrin alpha6 and integrin beta1. Their capacities of migration via vascular system and taking up residence in the primary gonadal ridge were further demonstrated by transferring to the dorsal aorta of stage 17 recipient embryos. These results suggested that our culture system is able to maintain chicken gPGCs for long-term in vitro culture without losing their capacity to express pluripotent markers and to integrate into the gonads.

The effect of electrical field strength on activation and development of cloned caprine embryos.

The activation procedure used in nuclear transfer (NT) is one of the critical factors affecting the efficiency of animal cloning. The purpose of this study was to compare the effect of two electrical field strengths (EFS) for activation on the developmental competence of caprine NT embryos reconstructed from ear skin fibroblasts of adult Alpine does. The NT embryos were obtained by transfer of the quiescent fibroblasts at the fourth passage into the enucleated metaphase II (M II) oocytes. Four to five hours after electrical fusion, the NT-embryos were activated by EFS either at 1.67 or at 2.33 kV/cm and immediately incubated in 6-DMAP (2 mM) for 4 h. The cleavage rate of the NT-embryos activated with 2.33 kV/cm was greater than that activated with 1.67 kV/cm after in vitro culture for 18 h (65.6% versus 19.6%, p < 0.001). No pregnancy was found in 14 recipient does after transferring 51 NT embryos at 1-2 cell stages activated with 1.67 kV/cm. In contrast, two of the seven recipients were pregnant and gave birth to three kids after transferring 61 NT embryos at 1-2 cell stages activated by 2.33 kV/cm. The birth weights of three cloned kids were within the normal range of Alpine goats. However, one kid died 1h after birth while the remaining two are still healthy. DNA analysis by polymerase chain reaction (single-strand conformation polymorphism, SSCP) confirmed that the three kids were genetically identical to the nuclear donor.

Mice immunized with DNA encoding a modified Pseudomonas aeruginosa exotoxin A develop protective immunity against exotoxin intoxication.

A recombinant plasmid, which contains the Pseudomonas aeruginosa exotoxin A (PE) gene with a C-terminal deletion, was inserted into expression vector pSecTag Xpress. The expression of this bacterial exotoxin in an animal cell was first demonstrated in 3T3 cell by transient transfection and western blot assay. Recombinant plasmid DNA was then injected intramuscularly to BALB/c mice, anti-PE specific antibodies were found in all animals vaccinated with plasmid containing the PE gene and with 'detoxicated' recombinant PE protein. Mice vaccinated with DNA were protected from the intoxication of lethal dosage of P. aeruginosa exotoxin A. Our results indicated that mice vaccinated with DNA encoding the PE gene could express PE protein in vivo, induced specific immune response, and provided sufficient protective immunity that safeguarded mice from the injection of lethal dosage of PE toxin.