[Genome array on differentially expressed genes of muscle tissue in intact male and castrated Qinchuan cattle]

Bovine genome array was used to construct gene expression profile to screen differentially expressed genes of the Longuissimus dorsi muscle (LDM) tissue between intact male and castrated Qinchuan cattle and investigate the molecular mechanism related to meat quality differences between the two groups. Significance Analysis of Microarray (SAM) methods was used to identify the differentially expressed genes. Go (gene ontology) and the pathway analyses were conducted on differentially expressed genes using a free web-based Molecular Annotation System 2.0 (MAS 2.0). About 11,000 probe sets represented about 10,000 genes were detected in LDM of 36 months old Qinchuan cattle. A total of 143 genes were identified to be differentially expressed genes. They were mainly involved in collagen fibril organization and synthesis, regulation of cell growth and development, ubiquitin-dependent protein catabolism, and striated muscle contraction etc. The enriched pathways mainly included ECM-receptor interaction, cell communication, and focal adhesion etc. Subsequently, real-time PCR was performed to validate eight differentially expressed genes screened out by the microarray approach and sufficient consistency was observed between the two methods. According to our study and published papers, the regulated pathways including ECM-receptor interaction, cell communication, focal adhesion, tight junction and genes including COL3A1, COL1A1, COL1A2, SPP1, FBN1, MMP2, ECM1, MYH3, MYH8, S100A4, ASPN, CFD etc were considered as the most important pathways and genes involved in meat quality differences between males and castrated Qinchuan cattle. Moreover, some genes had no annotation in GenBank were screened out, which were presumed to be unknown new genes. The roles that they may play in muscle metabolism need to be clarified in future.