ABSTRACT: Texel and Ujumqin sheep show obvious differences in muscle and fat growth, so they are ideal models not only to understand the molecular mechanism in prenatal skeletal muscle development, but to identify the potential target genes of myostatin. To elucidate the phenotypic variation between the two sheep breeds and the dynamic characteristics of gene expression in skeletal muscle during the development, we examined the development of skeletal muscle in transcriptome-wide level at 70, 85,100,120 , 135 days post coitus (dpc),birth, 1 month and 2 month. Using the specialized and standardized sheep transcriptome-wide oligo DNA microarray (Agilent), we analyzed the transcriptomic profiles of longissmuss dorsi muscle from fetuses of Texel and Ujumqin sheep. We characterized dynamic transcriptome-wide profiles that accompany the prenatal skeletal muscle and fat development in Texel and Ujumqin sheep respectively, and compared the difference in profiles of gene expression between the two sheep breeds at the same developmental stage.Some potential myostatin target genes and other genes controlling the growth of skeletal muscle and adipose were identified for further examinations. Our findings not only contribute to understand the molecular mechanism of prenatal skeletal muscle development in large precocial species, but also provide some clues for human myopathy and obesity at prenatal stages. Moreover, we also can identify putative candidate genes for meat quality traits in farm animals. Longissimus dorsi muscles were sampled from five prenatal development stages (70, 85, 100, 120 and 135 day of gestation) in Texel and eight development stages (at 70, 85, 100, 120, 135 days post coitus (dpc), birth, 1 month and 2 month) in Ujumqin sheep. There were at least three replicates at each development time in each breed. Two gene expression experiments were conducted with a total of 40 hybridizations.
