Study On The Content Of Beta Carotene And Its Enzymes Of Degradation In Yak Tissue At Different Nutrient Period

The adult yak(Bos mutus) fat’s having obvious yellow color has special ability of enrichment for carotenoids including β-Carotene. This phenomenon is not caused by genetic defects and pathology, but a result of its nutrient metabolism adapts special plateau environment.In order to study the relationship between the enrichment of β-carotene and the metabolic enzymes, the content of β-carotene and vitamin A in yak tissues were analysed by using HPLC, and the content of enzyme and its activity were also analysed, and the m RNAs expression of BCMO1 in different yak tissues were analysed by using fluorescence quantitative PCR at the different nutrition periods, and the BCMO1 protein expression in yak tissues were analysed by using Western blotting at the different nutrition periods.(1) The contents of β-carotene in blood serum, liver, duodenum, jejunum and rumen are higher at rich nutrition period than nutrition deficiency period(P<0.05), there is no difference of β-carotene content in liver and fat at two nutrition period(P>0.05).The contents of vitamin A in liver are higher at rich nutrition period than nutrition deficiency period, and there is no difference in content of vitamin A in ileum, intestinal content and rumen tissues at different nutrition periods(P<0.05).(2) The activities of β-carotene degradation enzyme in yak liver and pancreas are higher at rich nutrition period than nutrition deficiency period. On the contrary, the activities of enzyme in other tissues such as duodenum, kidney, and rumenare are higher at nutrition deficiency period than rich nutrition period.(3) There is an expression of BCMO1 m RNA in every tissue at different nutrition period. The expression of BCMO1 m RNA in duodenum, kidney, rumen and jejunum is much higher at nutrition rich period than nutrition deficiency period(P<0.05). On the contrary, the m RNA expression in muscles and pancreas are higher at rich nutrition period than deficiency period.(4) BCMO1 protein expression in yak duodenum, jejunum, kidney, muscle and rumen are lower at rich nutrition period than deficiency period(P<0.05), while BCMO1 protein expression in liver is higher at rich nutrition period than nutrition deficiency period. There is no difference of BCMO1 protein expression in lungs and ileums at different nutrition periods(P>0.05).We can get some conclusions basing on results. Yak tissues such as fat can concentrate large amounts of β-carotene at rich nutrition period. During the period of vitamin A deficiency, the β-carotene is degradated into VA in some tissue. There is a relationship between β-carotene enrichment in yak fat and β-carotene degradation enzyme. In addition to the liver and pancreas, the activity of β-carotene degradation enzyme in other tissues is higher at deficiency period than rich nutrition. From view of the level of gene and protein expression, expression level of β-carotene 15, 15 ’-oxygenase(BCMO1) is lower in most tissues at rich nutrition period than deficiency period. According to the β-carotene feedback metabolic mechanism, the β-carotene metabolites(retinoic acid, etc.) has ability of feedback inhibition of β-carotene 15, 15’- oxygenase(BCMO1) expression.