Study On Effects Of No.0 Diesel Oil Water-soluble Fraction On Antioxidant Defense Systems In Liver, Spleen And Kidney Of Sebastiscus Marmoratus

In this study, Sebastiscus marmoratus, which treated with 0 # diesel oil water-soluble fraction (DWSF) at concentrations of 0.02, 0.1, 0.5 mg/L in indoor experimental condition as the experimental materials, was used to search the potential influence of the antioxidant defense systems on organs such as liver, spleen and kidney. Half of sea water was replaced with the same concentration one every day and samples were taken on the 0^th, 7^th, 28^th and 84^th days in the exposure time and on the 7^th and 28^th days after released from DMSF respectively. The biochemical parameters of the antioxidant defense systems of immune organs, namely level of reactive oxygen species (ROS), content of malondial dehyde (MDA) and reduced glutathione (GSH) and activity of superoxide dismutase (SOD), catalase (CAT), glutathione-S-Transferase (GST) and glutathionesu peroxidase (GPx) were tested. The toxic effect and potential function mechanism of DWSF exposure on the antioxidant defence systems of Sebastiscus marmoratus were discussed after biochemical analysis for important enzymes activity. The results showed:1. Effects of DWSF exposure on hepatic antioxidant defense systems of Sebastiscus marmoratus were detected. The activity of SOD, GPx and content of GSH in liver have a significant positive relation with the content of DWSF in habitat. Of all the hepatic antioxidant biochemical indicators, GSH represented the most sensitive to DWSF, but the activity of CAT and GST had slower response, which might be caused by the earlier induction of GPx with the same function. The level of ROS in the low concentration group and the content of MDA in the high concentration group decreased significantly during the period of DWSF exposure owing to the decreasing of the lipid peroxidation level caused by the function of the antioxidant enzymes, which indicated liver tissue with a detoxification function showed a strong antioxidant function. Consequently, hepatic antioxidant defense systems of Sebastiscus marmoratus is suitable to be choosen as a biomarker for marine oil pollution.2. Effects of DWSF exposure on splenic antioxidant defense systems of Sebastiscus marmoratus were detected. The antioxidant enzymes other than CAT were more sensitive to the pollutants exposure with concentrations of DWSF and the middle metabolites accumulated in the spleen. In the early exposure, the level of ROS and the content of MDA significantly decreased that indicated a lower level of lipid peroxidation. Most of the antioxidant enzyme activity of the spleen was inhibited, moreover, the activity GST and SOD and the content of GSH had a significant negative relation with DWSF concentrations in habitat caused by GPx inducement, which greatly weakened the capacity of detoxification of the spleen and increased the extent of oxidative damage. After the cancellation of pollution in the high concentration group, SOD activity remained significant inhibition, which also showed that the antioxidant function of Sebastiscus marmoratus spleen might have been injuried to a certain degree. Therefore, the physiology and biochemical indicators of the fish spleen were the potential biomarkers worth being studied.3. Effects of DWSF exposure on renal antioxidant defense systems of Sebastiscus marmoratus were detected. Because of the DWSF stress, the level of ROS of kidney of Sebastiscus marmoratus had been in a low state in most of the time, the content of MDA in the low concentration group significantly decreased or decreased firstly and then rose to the original state in the high concentration group, which indicated that the level of oxidation had been stabilized under the elimination of the antioxidant enzymes to oxygen free radicals. Moreover, GST activity decreased significantly in the early exposure, SOD activity was inhibited first then induced, CAT activity was induced significantly in the low concentration group in the later period and inhibited in the high concentration group in the early period, and GPx activity had been inhibited during the early exposure. Therefore, the more the degree of pollution increased, the slower the adaptive response of GSH to diesel oil became. It was obvious that the kidney of Sebastiscus marmoratus has an effective mechanism to protect itself from oxidative damage and is suitable to be a biomarker for a low concentration of oil pollution.To sum up, the antioxidant defence systems on organs of Sebastiscus marmoratus such as liver, spleen and kidney are sensitive to the long-term exposure of low level DWSF in the environment. The antioxidant defense systems of liver, spleen and kidney can be considered as biomarkers for the oil pollution of the environment. Of all, CAT activity of liver and spleen has the lowest sensitivity, Which possibly caused by the earlier induction of GPX with the same function, so the change of CAT activity can not be considered as a monitoring indicator of DWSF pollution in this experiment. Compared with the effect of DWSF on GPx / MDA in organs of Sebastiscus marmoratus, the antioxidant capacity of the antioxidant defense systems of these three organs in Sebastiscus marmoratus on DWSF appears as below: liver > kidney > spleen.