Molecular cloning, expression, and imprinting status of maternally expressed gene 8 (Meg8) in dairy cattle

At present, small number imprinted genes have been reported in cattle compare to human and mouse. Maternally expressed gene 8 (Meg8), a non-coding gene, have been identified maternally expressed in mouse and sheep, but its sequences and imprinting status have not been established in cattle. In this study, the full-length of cattle Meg8 cDNA sequence was obtained by reverse transcript polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends (RACE) method, which has a high homology in exons sequences with the corresponding region of sheep Meg8. The isolation of cDNA sequence showed the presence of multiple splice variants in cattle Meg8 gene. The Meg8 was found to be expressed in all adult examined tissues, including heart, liver, spleen, lung, kidney, brain, subcutaneous fat and skeletal muscle. A single nucleotide polymorphism (SNP) was identified in exon 6 by Single-Strand Conformation Polymorphism (SSCP), and used to distinguish between monoallelic and biallelic expression in cattle tissues. The expression analysis of Meg8 in a heterozygous cattle showed that only one parental allele was expressed in all examined tissues, suggesting that Meg8 is imprinted in cattle.