| L.japonicus is one of the economic species of large-scale aquaculture in coastal areas of China,and the high concentration of ammonia and nitrite are important factors restricting high-density and intensive aquaculture;Curcumin plays an important role in enhancing stress resistance of fish.In this thesis,we study the ammonia,nitrite and curcumin influence on sea bass,by discussing the change of the growth metabolism and disease-resistant genes expression level in head-kidney,spleen,gill,liver,and muscle,determines the best concentrations of curcumin as feed additive,and the change trend of related genes expression levels in different periods.The main findings are as follows:1.The results showed that the expression level of immune-related genes such as heat shock proteins 70 and 90 were upregulated in the head-kidney,spleen,gill,liver,and muscle tissues under ammonia and nitrite stress.Glutamine synthetase（GS）expression increased to different degrees under ammonia and nitrite stress,while glutamate dehydrogenase（GDH）in the stress group upregulated in the gills.The expression of carbonic anhydrase（CA）was upregulated in the spleen and gill tissue under ammonia or nitrite stress.Expression of leptin（LEP）was upregulated in the muscle,gills and liver under nitrite stress;under ammonia stress,LEP expression did not fluctuate significantly in the spleen or gill.Insulin-like growth factor-1（IGF-1）was downregulated in the spleen,while did not fluctuate obviously in the muscle and head-kidney under ammonia stress.These results indicate that ammonia and nitrite stress led to an upregulated immune related indexes response and increased metabolic activities in L.japonicus,and provides reference suggestions for response status of these health markers answering the outside environment intimidation.The results indicated that the expression of immune-related genes such as heat shock proteins 70 and 90 were upregulated in the head-kidney,spleen,gill,liver,and muscle tissues under ammonia and nitrite stress.2.According to the weight growth rate of L.japonicus and the broken line equation,the optimal adding ratio of curcumin in L.japonicus feed was 0.03 g/kg.At curcumin levels of 30 mg/kg and 60 mg/kg,gene expression of HSP70 was up-regulated in the head-kidney,spleen and gill,but down-regulated in muscle,liver and intestine;and meanwhile,Hsp90 was up-regulated in the head-kidney,spleen,liver,gill and intestine.The expression of gene GS was up-regulated in the head-kidney,spleen,muscle and gill.The expression of gene GDH was up-regulated in the head-kidney,spleen,muscle,liver and gill.When curcumin level was 15 mg/kg and 30 mg/kg,the accumulation of GDH in tissues was up-regulated obviously.The expression level of gene CA was down-regulated in the head kidney,liver and muscle and up-regulated in the gill.Leptin（LEP）was up-regulated in the head kidney,spleen,liver and gill.When curcumin level was 15 mg/kg,IGF-1 was enriched in the muscle and gill;besides,the expression of gene IGF-1 was up-regulated in the head kidney,spleen,liver and gill when curcumin level was 30 mg/kg.Under the stress of NH4+-N and NO2--N,the changes of genes related to metabolism and disease resistance of L.japonicus can provide reference value for healthy aquaculture at gene level and has certain guiding significance in the process of high-density and intensive.The development and application of curcumin as feed additive is significant to the sustainable development of intensive aquaculture,maintain the food safety and human health by improving the growth metabolism and disease resistance of aquatic animals. |
