Isolation, cDNA sequence analysis and tissue expression profile of a novel swine gene differentially expressed in the Longissimus dorsi muscle tissues from Large White x Meishan cross combination

摘要

In order to study the molecular mechanism of heterosis in pigs, the mRNA differential display technique was performed to investigate the differences in gene expression in the Longissimus dorsi muscle tissues from Large White x Meishan cross combination. One novel gene differentially expressed between the hybrids and the purebreds was isolated and subsequently identified using semi-quantitative reverse transcriptase polymerase chain reaction (RT-PCR) and its complete cDNA sequence was 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 revealed that the open reading frame of this gene encodes a protein of 188 amino acids that contains the putative conserved domain of the PRA1 family protein and this protein has high homology with the PRA1 family protein 3 of three species—rat (88% ), human (88% ), and mouse (87% ), —so that it can be defined as swine PRA1 family protein 3. The phylogenetic tree analysis revealed that the swine PRA1 family protein 3 has a closer genetic relationship with the human PRA1 family protein 3 than with those of mouse and rat. The tissue expression analysis indicated that swine PRAlfamily protein 3 gene is highly-expressed in muscle and fat, moderately in spleen, weakly in heart, kidney, ovary, lung, and almost not expressed in small intestine and liver. The function of this gene and the relationship between this gene and heterosis are also discussed.