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The purpose of this study was to compare between the histochemical characteristics and the expression of epidermal growth factor (EGF) and it's receptor (EGFR) in the submandibular gland (SMG) of adult yaks and yellow cattle. The SMG tissues of yaks and yellow cattles were collected for histochemical, immunohistochemical (IHC), immunofluorescence (F‐IHC)，real‐time quantitative polymerasechain reaction (RT‐qPCR) and Western blotting methods. The results showed that the striated ducts of SMG were highly developed and connected to the intercalated ducts, which were shorter and directly connected to the acini. Compared with yellow cattle, yak SMG contains more mucous acini. Immunofluorescence showed significant expression of EGF and its receptor in both striated and intercalated ducts of these two species of cattle. Statistical analysis divulged that the distribution density of EGF and EGFR in the SMG of the yak was both significantly higher than that in yellow cattle (p < 0.05). Furthermore, the mRNA expression of EGF and EGFR in yak SMG was also higher than that in yellow cattle. The above results indicated that the intercalated ducts and striated ducts are the main expression sites of EGF and EGFR, the acidic mucin and EGF secreted from SMG of yak were more than that from yellow cattle. The results of this study provide powerful data for the study of physiological functions of submaxillary gland in ruminants and also provide important clues for the study of adaptive physiological mechanisms in plateau organisms. [ABSTRACT FROM AUTHOR]

Bioactive components in five tisues (longissimus muscle (LSM), biceps femoris muscle (BFM), liver (LV), subcutaneous adipose tissue (SAT), and abdominal adipose tissue (AAT)) of yak in Tibet and yellow cattle in Hubei were investigated. Yak was significantly higher (p<0.01) than yellow cattle in the squalene content of lipids of BFM (59.82/19.07 mg/100g), LSM (20.99/7.81 mg/100g) and LV (6.94/2.67 mg/100g), respectively, but not in SAT and AAT (p>0.05). Yak was also significantly higher (p<0.05) than yellow cattle in the total tocopherol content. Additionally, yak hepatic lipids showed the highest content of saturated fatty acids (58.11%) and polyunsaturated fatty acids (PUFA, 25.81%) and the lowest content of monounsaturated fatty acids (MUFA, 16.08%), while yellow cattle AAT had the highest content of MUFA (47.54%) and the lowest content of PUFA (2.36%). The considerable differences between the two in composition suggest that the five tissues of yak are potential sources of bioactive components and essential fatty acids for humans. Practical applications: The results from the analysis of the contents of squalene, tocopherols, total lipids，moisture, ash, and pH and fatty acid profile in the studied tissues of Tibet yak and Hubei yellow cattle provide useful information for developing functional foods using yak meat or other tissues as materials. Comparison of squalene and total tocopherol contents in different tissues of yak and yellow cattle. [ABSTRACT FROM AUTHOR]