Abstract: To select the best stable reference genes and investigate the developmental expression patterns of AKT gene in sheep fetal muscle. Quantitative RT-PCR was conducted for B2M, GAPDH, RPLPO, RPS18 and SDHC and also applied to investigate AKT mRNA expression at the gestation of 70 d, 85 d, 100 d, 120 d and 135 d in longissimus dorsi muscle of Texel and Ujumuqin sheep. The five reference genes of expression stability were analyzed by the GeNorm software, and the result showed that RPS18＞RPLPO＞SDHC＞B2M＞YWHAB. Furthermore, SDHC, RPLPO and RPS18 were identified as the most stable reference genes in the present study. In all the five stages, the expression patterns of AKT were dissimilar in the two sheep breeds. Strikingly, at the gestation of 85 d and 120 d, the expression of AKT reached their peak values in Texel,in contrast, in Ujumuqin it was at 100 d. These findings were consistent with our previous study which reflected the histological characteristics during the second half of gestation in the two sheep breeds, and this further verify that the surges in myofiber hyperplasia occurred at 85 d and 120 d in Texel sheep, whereas a unique proliferative surge appeared at 100 d in Ujumqin sheep. The results indicated that the transcript levels of AKT gene exhibited specific developmental expression changes between Texel and Ujumuqin sheep, and provided some data for further study on the effect of AKT gene.

Key words: Texel; Ujumuqin; AKT gene; quantitative RT-PCR; reference genes; developmental expression patterns