Gene Expression Patterns Analysis And The Comparative Analysis On Transcriptional Profiling Of Muscle Tissue From Chinese Major Indigenous Species Of Cattle

As the problem of tenderness variability, improving the meat quality, especially the tenderness of beef, is of major importance in the meat industry. From the point of molecular mechanism of meat to view to consider how to improve the quality of beef is the most fundamental solution. Quality traits of meat are governed by biological processes during growth and development that are regulated by multiple genes, a variety of metabolic pathways and highly complex life activities that results in growth, development and fat deposition. Microarray technologies, which can measure the expression of thousands of genes simultaneously and identify subtle changes in expression between different biological states, provide an approach to studying differences in gene function. Three typical Chinese indigenous bovine species including yellow cattle (Bos taurus), yak (Bos grunniens) and buffalo (Bubalus bubalus) have their unique appearance characteristic and physiological property; they have great potential for meat production and are worth to develop. It is great significance to investigate the molecular mechanism involved in regulation of quality traits of meat in order to improving China's beef cattle breeding. Therefore, the genechip Bovine Genome Araay were used to construct the characteristics of the transcriptional profiling and screen the important genes and regulated pathways in the muscle tissue on Qinchuan cattle that is on behalf of Chinese indigenous yellow cattle, Qinghai yak and Guangxi buffalo. The results were confirmed by real-time quantitative PCR. The results are as follows:(1) The results of sex affecting the meat characteristics of Qinchuan cattle (Intact males, IM; Castrated males, CM; Females, FM) revealed that significant sex differences were found in the physicochemical characteristics (PCC) of longissimus thoracis muscle (LTM): the IM group had higher shear value, pH, drip and cooking losses, and contents of ash and hydroxyproline (Hyp) than the CM and FM groups (p < 0.05), as well as lower ether extract content and lightness (p < 0.05); Both the IM and CM groups had lower water content and higher protein content than the FM group (p < 0.05); Sex differences were also observed in contents of C14:0, C14:1, C18:1, saturated fatty acids (SFA), mono-unsaturated fatty acids (MUFA) (p < 0.05), and unsaturated fatty acids (UFA) between the IM and the CM, or the IM and FM groups (p < 0.05), but not between the CM and FM groups (p < 0.05). (2) The gene expression profiles detected 10960~11631 probes in Qinchuan muscle tissue, which maily involved in protein biosynthesis, ATP synthesis, glycolysis and regulation of transcription and translation etc. Total of 107 differentially expressed genes were sheared by IM vs. CM and IM vs. FM comparison groups. Gene ontology (Go) analysis showed that they were mainly involved in 44 enriched classification, including cell adhesion, protein polymerization, hypoxia response etc. Regulatory pathway analysis revealed 17 enriched pathways, such as ECM-receptors reaction, cell communication, focal adhesion etc. Total of 2 differentially expressed genes were screened in FM vs. CM comparision groups, such as X (inactive)-specific transcript (XIST).(3) Significant differences were observed in PCC of LTM between Qinghai yak and Qinchuan cattle such as protein and ether extract contents, contents of ash and Hyp, tenderness etc. The gene expression profiles detected 10631 probes in Qinghai yak muscle tissue, which maily involved in protein biosynthesis, ATP synthesis, glycolysis and intracellular transport etc. Total of 1922 probes that were differentially expressed in muscle tissues between Qinchuan cattle and Qinghai yak were screened out, 633 probes were up-regulated and 1259 probes were down-regulated in the muscle tissue of Qinghai yak, which mainly involved in ubiquitin mediated proteolysis, cellular transport, sugar metabolism, transcription and translation regulation and immune response etc.(4) Significant differences were observed in PCC of LTM between Guangxi buffalo and Qinchuan cattle such as protein and ether extract contents, tenderness etc.The gene expression profiles detected 8883 probes in Guangxi buffalo muscle tissue at 36 months., which maily involved in protein biosynthesis, ATP synthesis, glycolysis etc. Total of 2340 probes that were differentially expressed in muscle tissues between Qinchuan cattle and Guangxi buffalo were screened out, 650 probes were up-regulated and 1690 probes were down-regulated in the muscle tissue from Guangxi buffalo, which mainly involved in cholesterol homeostasis, transcriptional regulation, glycolysis, oxidation reduction etc.(5) According the results of comparative analysis of transcriptional profile of LTM from Qinchuan cattle with different genders and related literature, the regulated pathways including ECM-receptors reaction, cell communication, focal adhesion, tight junction and Glycan structures degradation were closely associated with meat quality traits of Qinchuan cattle and genes including COL1A2, COL1A1, SPP1, MMP2, MYH3, MYH8, CFD were considered as important candidate genes affecting meat quality traits and well worth further studing on.