Effects Of Temperature And Salinity On The Activities Of Antioxidant Enzymes And Hsp70Mrna Expression Of Danphniopsis Tibetana Sars

Environmental factors (temperature, salinity, pH, etc.) not only can affect thebreathing and metabolism of aquatic organisms, but also free radicals can causemetabolic disorders. The immune defense capabilities will be decreased If theorganism is in the effect of stress for a long time, thus affecting its normal growth.Itis of great significance to study the antioxidant effect and heat shock protein ofaquatic organisms to explore the mechanism of its adaptation to the environmentand improve the antioxidant immunity of aquatic organisms. The experiment wasdesigned to evaluate the effects of temperature and salinity on the activities ofantioxidant enzymes and lipid peroxidation of Danphniopsis tibetana Sars under theconditions of1500lx, photoperiod(12L:12D) and PH8.1in the laboratory, and underthe same conditions, research the effect of temperature and salinity on HSP70geneexpression of Daphniopsis tibetana Sars by molecular biology methods to explorethe tolerance mechanisms on the environment. The major results and conclusionsare as follows:1. Effects of Temperature and Salinity on the Activities of Antioxidant enzymesand Lipid peroxidation of Danphniopsis tibetana SarsThe experiment was designed to evaluate the effects of temperature（16℃、19℃、22℃、25℃、28℃）and salinity（5、10、15、20、25）on the activity oftotal superoxide dismutase(T-SOD)、 glutathione peroxidase(GPX) and maleicdialdehyde(MDA) of Danphniopsis tibetana Sars by ecological method under thelaboratory conditions.The results showed that temperature and salinity inducedadaptive responses such as increase the activities of SOD、GPX and the content ofMDA with temperature and salinity raised to28℃,25, the maximum were37.18±1.97U/mg﹒μg、75.1±9.96U/mg﹒μg、12.24±2.12nmol/mg﹒μg;48hours later, the experimental groups of high temperature and lower salinity(25~28℃、5~10) and the experimental groups of high temperature and highersalinity (25~28℃、20~25) had interactive effects. when28℃,S=5, those raised tothe maximum19.25±3.48U/mg﹒μg、59.95±4.66U/mg﹒μg、4.98±0.66nmol/mg μg. There were interactive effects between the two factors on theantioxidant enzymatic activities(SOD、GPX) and lipid peroxidation(MDA) inDanphniopsis tibetana Sars（P<0.01）.2. Effect of temperature and salinity on hsp70mRNA expression of Daphniopsis tibetana SarsPhysiological responses to temperature and salinity reflect the evolutionaryadaptations of organisms to their environment and the capability of animals totolerate stress. To study the physiological adaptations of Daphniopsis tibetana Sarsto temperature and salinity stress, hsp70mRNA expression levels of Daphniopsistibetana Sars were analyzed by SYBR Green fluorescence quantitative RT-PCR.The results showed that temperature and salinity induced adaptive responses such asincrease hsp70mRNA expression first and then decrease and then increased as thetemperature increased. When the temperature and salinity raised to22℃,10, themaximum was7.60.72, the hsp70mRNA expression was7times higher than thecontrol group(16℃，15).There were significant difference between the groups of22℃、28℃and the other groups. The expressions of hsp70were significantlydifferece with the amount of salinity changes （P<0.05）;48hours later, thetendency of hsp70expression level was increased with the temperature raised. Thehsp70expression level of D. tibetana was much higher than the control group（P<0.05）, the maximum was6.360.22, the hsp70mRNAexpression was6timeshigher than the control group(16℃，15). The hsp70expressions of high temperature(25to28℃) and high-salt groups (20to25) were significantly increased with thetime prolonged. The hsp70expression level of D. tibetana was more sensitive to thesalinity-up treatment and the salinity-drop treatment.