Abstract: Gene GDF9(growth differentiation factor 9)and BMP15(bone morphogenetic protein 15)of yak were used as research subject；then 2 exon fragments of GDF9 and BMP15 were cloned by PCR, and the expressions of GDF9 and BMP15 as well as targeted miRNA were analyzed by RT-PCR.The results were as follows.The cloned and amplified exon fragments were analyzed by bioinformatics；the exons of yak gene GDF9 were 411 bp and 1 082 bp, encoding 453 amino acids；the lengths of exons in yak gene BMP15 were 323 bp and 802 bp separately, encoding 372 amino acids.The protein encoded by GDF9 was hydrophilic, containing one signal peptide and 15 potential phosphorylation sites；the protein encoded by BMP15 was also hydrophilic, and owing no signal peptide and 6 potential phosphorylation sites.The expressions of GDF9 and BMP15 in different tissues were examined by RT-PCR.The results showed that GDF9 expressed relatively high in ovary and uterus, and higher in ovary than others tissues, and no expression in heart, kidney, pancreas, and spleen；BMP15 was only detected in ovary.With TargetScan, the target miRNA of yak gene GDF9 and BMP15 were predicted and the expressions of target gene bta-miR-193a-3p and bta-miR-193b of GDF9 in heart, spleen, lung, kidney and uterus were analyzed.miRNAs genes were examined with RT-PCR；the results indicated that bta-miR-193a-3p in the spleen expressed significantly higher than in others tissues, and no expression in heart, lung and uterus；bta-miR-193b expressed lower in lung than spleen and uterus, and no expression was detected in heart and kidney.

Key words: Yak, GDF9, BMP15, miRNA