Molecular Cloning of the Porcine HTRA3 Gene and Association of a SNP with Litter Size Traits.

HtrA serine peptidase 3 (HTRA3) is an important reproduction-related gene. In this study, we cloned the full-length coding sequence of the porcine HTRA3 gene using RT-PCR. Sequence analysis of this gene revealed that the pig HTRA3 gene encodes a protein of 453 amino acids, which has high homology with the HTRA3 protein of five species: water buffalo (96 %), killer whale (96 %), sperm whale (96 %), Yangtze River dolphin (96 %) and smalleared galago (93 %). Phylogenetic analysis revealed that the pig HTRA3 gene has a closer genetic relationship with the HTRA3 gene of cattle. PCR-HpaIIRFLP was established to detect the GU373693:c.1140 G>A substitution of the porcine HTRA3 gene coding sequence, and eight pig breeds displayed obvious genotype and allele frequency differences at this mutation locus. Association of this SNP with litter size traits was assessed in Large White (N = 200) and Landrace (N = 200) pig populations, and the results demonstrated that this polymorphic locus was significantly associated with the litter size of all parities in Large White and Landrace sows (P < 0.05). Therefore, the HTRA3 gene could be a useful candidate for increasing the litter size in pigs. These data serve as a foundation for further insight into this novel porcine gene.

Molecular characterization, polymorphism and association of porcine IBP4 gene.

The complete coding sequence of the porcine IBP4 gene was isolated using RT-PCR. Sequence analysis showed that the porcine IBP4 gene encodes a protein of 259 amino acids which shares high homology with the insulin-like growth factor binding protein 4 (IBP4) of eight species: cattle (97 %), goat (97 %), chimpanzee (97 %), human (96 %), giant panda (96 %), sheep (95 %), Sumatran orangutan (95 %) and rabbit (93 %). This gene is structured in four exons and three introns as revealed by computer- assisted analysis. Phylogenetic analysis revealed that the porcine IBP4 gene has a close genetic relationship with the IBP4 gene of cattle. Polymorphism analysis indicated that there was an A/G substitution in the position of 134 bp of exon 2 and this mutation did not alter the encoded amino acids of the porcine IBP4 gene. PCR-Hha I-RFLP revealed that eight pig breeds displayed obvious genotype and allele frequency differences at this polymorphic locus. Association of this SNP with litter size traits was assessed in Large White (N = 100) and Landrace (N = 100) populations, and the results demonstrated that this polymorphic locus was significantly associated with the litter size of the first parity in Large White sows and Landrace sows (P <0.05). These data serve as a foundation for further insight into this novel porcine gene.

A novel porcine gene--SLC9A3R2, differentially expressed in the longissimus muscle tissues from Meishan and Large White pigs.

The mRNA differential display technique was performed to investigate the differences of gene expression in the longissimus muscle tissues from Meishan and Large White pigs. One novel gene that was differentially expressed was identified through semi-quantitative RT-PCR and the cDNA complete sequence was then obtained using the rapid amplification of cDNA ends (RACE) method. The nucleotide sequence of the gene is not homologous to any of the known porcine genes. The sequence prediction analysis revealed that the open reading frame of this gene encodes a protein of 337 amino acids that has high homology with the solute carrier family 9 isoform 3 regulator 2 isoform a of four species--human (92 %), mouse (91 %), rat (90 %), rabbit (87 %)--so that this gene can be defined as swine SLC9A3R2 gene. The phylogenetic tree analysis revealed that the swine SLC9A3R2 gene has the closest genetic relationship with the SLC9A3R2 gene of human. This gene is structured in seven exons and six introns as revealed by computer-assisted analysis. The tissue expression analysis indicated that the swine SLC9A3R2 gene is differentially expressed in different tissues. Our experiment is the first to establish the primary foundation for further research on the swine SLC9A3R2 gene.

A novel sheep gene, MMP7, differentially expressed in muscles from black-boned sheep and local common sheep.

Differences in gene expression in muscles from Chinese black-boned sheep and local common sheep were investigated using mRNA differential display. One differentially expressed novel gene was identified through semi-quantitative RT-PCR, and the full-length cDNA sequence was then obtained using the rapid amplification of cDNA ends (RACE). The nucleotide sequence of this gene is not homologous to any of the known sheep genes, but it contains an open reading frame encoding a protein of 416 amino acids, which has high homology with matrix metallopeptidase 7 (matrilysin, uterine) (MMP7) of 10 species: bovine (93%), rhesus monkey (75%), human (74%), pig (73%), chimpanzee (73%), dog (73%), horse (72%), mouse (66%), rat (65%), and chicken (53%). Thus the novel gene can be defined as the sheep MMP7 gene. It was finally assigned to GeneID:100192317. The phylogenetic tree analysis revealed that the sheep MMP7 gene is closely related to the bovine MMP7. Our experiment is the first one to establish the primary foundation for further research on the sheep MMP7 gene.