Effects Of Continuing Heat Stress On Heat-Shock Protein HSP90? And HSP10 MRNA Expression,Tissue Injury And Blood Cell Apoptosis In Rainbow Trout(Oncorhynchus Mykiss)

Rainbow trout(Oncorhynchus mykiss)is a typical cold-water species of salmonid,which is sensitive to the temperature change.In the process of intensive net cage culture,the high temperature can easily lead to mass mortality or serious losses in yield of rainbow trout.Rainbow trout are considered to be a good model organism in many heat stress researches by reason of its sensitivity to the environment and heat stress.The study aimed to explore the molecular mechanism of rainbow trout in response to heat stress,in order to improving the ability of rainbow trout in feeding management level,controlling the mortality and increasing the production efficiency.The full-sibs were selected as objects in this study,have determined m RNA expression of HSP90? and HSP10 gene in different tissues(liver,gill,spleen,mid-kidney,heart,brain and muscle),blood cell apoptoic and have observed morphological structure of liver.The results as follows:1.The m RNA expression of HSP90? and HSP10 changed in tissues of rai nbow trout,and the expression responded in a tissue-specific manner to heat st ress.HSP90? was mainly expressed in brain,heart and liver during heat treat ment,and HSP10 was mainly expressed in liver and heart.In the heat stress p rocess,the expression of HSP90? gradually increased in gill,mid-kidney,brain,heart and muscle,but in liver was significantly higher at 21?,25? and 26? than other temperature(p<0.05);and maximum expression at 24?in splee n,significantly higher than 18? and 21?(p<0.05).The expression of HSP10 was not influenced by temperature in the brain;but in liver,heart and muscle the expression have different degrees up-regulation;in the gill the expression i ncreased continuously with the increase of temperature,the expression of mid-k idney was slightly decreased and then continued to increase,and the expression of HSP10 in spleen was significantly higher than the early temperature(p<0.05).2.The number of living cells at 25?was significantly lower than other temperature points(p<0.05),but at 26? it backed to normal levels.The number ofnecrotic cells and apoptoic at 25? was significantly higher than other temperature points(p<0.05),and 26? was significantly lower than 25?(p<0.05),but it still higher than 18?.3.Liver tissue pathological changes appeared at 21?,pathological changes gradually aggravated with the temperature increased.The liver tissue structure became irregular and widespread congestion,a wide range of cell degeneration,necrosis,apoptosis at 26?;The liver injury was worst and the original structure was destructed at 26?.4.As mentioned previously,the rainbow trout body showed significant clinical symptoms and gradually increased due to increased water temperature;HSPs expression responded in a tissue-specific and temperature dependence;live cells,apoptosis and necrosis were significantly affected by temperature;liver damage degree gradually aggravate.The rainbow trout had a heat stress response at 21? and the 25? was the critical temperature point for heat stress of rainbow trout.