Effect Of Heat Stress On MRNA Expression Of Heat-Shock Protein 40 And 90β Genes (HSP40 And HSP90β) In Rainbow Trout Oncorhynchus Mykiss

Rainbow trout(Oncorhynchus mykiss) is a cold-water species of salmonid, which suitable growth temperature in the range of 12°C~18°C. It was more vulnerable to the effects of water temperature changes. In order to master the HSP40 and HSP90β expression characteristics in different tissues and their regulation during water temperature rise. In this study, rainbow trout environmentally-accustomed to an aquatic environment of 18°C were exposed to an elevated temperature(25°C) and HSP40 and HSP90β expression in the gill, liver, spleen, heart, head kidney and brain were quantified using real-time fluorescent quantitative polymerase chain reaction(FQ-PCR) in unstressed and heat-stressed animals. Primary results are as follows:1. HSP40 and HSP90β m RNA expressions in heart and brain were higer than other tissues in unstressed group(P < 0.05); HSP40 and HSP90β m RNA expressions were significantly up-regulated in all tissues during heat-stressed(25°C). But, during heat stress, in all tissues HSPs expression were increased at the beginning, before decreasing.2. The greatest induction of HSP40 in heat-stressed animals was recorded in the heart, followed by liver and brain tissues. HSP40 expression in the gill reached the maximum after 2 h of heat stress. Brain, heart, liver, head kidney and spleen HSP40 expression levels were highest after 4 h of heat stress, respectively.3. The greatest induction of HSP90β in heat-stressed animals was recorded in the heart, followed by brain and liver tissues. The peak of Hsp90β m RNA expression was detected at 4 h in heart and spleen, 8 h in brain and 12 h in gill, head kidney and spleen tissues.4. Compared with unstressed group, the most obvious fold changes of HSP40 and HSP90β m RNA expression were recored in spleen and liver tissues during heat stressed group, this indicated that spleen and liver tissues were the most sensitive to heat stress.5. Compared with other tissues, the higher expression of HSP40 and Hsp90β were recored in heart, brain and liver tissues under heat stress group; HSP40 in heart and brain, and Hsp90β in liver and brain did not return to the comparison group(0 h) after HSR. We deduced that heart, brain and liver tissues were priority or strongly protected, and after heat stress eliminated, the recovery is relatively slow.