Effects Of PAHs Exposure On The Biomarkers Of Scallop Chlamys Farreri

The thesis mainly studied the effects of PAHs (BaP and BkF) on biomarkers of scallop Chlamys ferrari. The main contents include ① Effects of benzo(a)pyrene exposure on the biomarkers of scallop Chlamys farreri; ② Effects of benzo(k)fluoranthene exposure on the biomarkers of scallop Chlamys farreri; ③Effects of benzo (a) pyrene and benzo (k) fluoranthene mixture on the biomarkers of scallop Chlamys farreri; ④Responses of antioxidant systems and LPO level to benzo(a)pyrene and benzo(k)fluoranthene in the haemolymph of the scallop Chlamys ferrari.The authors mainly discussed the PAHs' toxicity and metablic cources in order to deduce the detoxification mechanism of chlamys ferrari, further, the suitable biomarkers of toxicology can be founded. 1 Effects of benzo (a) pyrene exposure on the biomarkers of scallop ChlamysfarreriA model to assess BaP exposure via water supply has been developed for the sentinel organism of China, Chlamys farreri. Scallops were cultured for 30 days in BaP exposure water (0.5μg/L, 1.0μg/L, 10.0μg/L and 50.0μg/L of culturing water). The determination of BaP concentration in culturing water was studied by HPLC. Different biomarkers of BaP exposure were measured to assess the metabolic state of the exposed scallops. 7-Ethoxyresorufin (H)eethylase assay (EROD) activity was assessed as indicator of phase Ⅰ biotransformation. Glutathione-S-transferase (GST) activity was measured as an indicator of the conjugation activity of phase Ⅱ biotransformation. Superoxide dismutase assay (SOD), Catalase (CAT) and Glutathione peroxidase determination (GPx) activities were assessed as potential biomarkers of oxidative stress, whereas contents of MDA was measured as an indicator ofoxidative perturbations. Under the developed conditions of exposure, significant changes were recorded each biomarker. EROD activity was significantly increased by BaP exposure and the activity of EROD is higher if the concentration of the BaP is higher in same sampling time. GST activity could increase in short time in low concentration BaP exposure and then dropped, whereas GST activity was significantly depressed in high concentration BaP exposure. The SOD, CAT, GPx activities could increase in low concentration BaP exposure, but in high concentration BaP exposure, the SOD, CAT, GPx activities were significantly depressed, gill was more sensitive to BaP than digestive gland, the gill' s detoxification function was less stronger than digestive gland, the digestive gland was the main tissue to deal with oxyradicals. The contents of MDA increased with the treating time and there had the positive correlation (concentration-effect) between the MDA contents and the concentrations of the BaP exposure. From our studies, we can see that the biomarkers determined in this experiments have the most important relationship in detoxification. GST, SOD, CAT and GPx showed the greatest utility as biomarkers of oxidative stress, whereas EROD, LPO appeared to be associated with BaP. Controlled laboratory experiments designed to simulate field exposure scenarios are particularly useful in ascertaining biomarkers suitable for use with complex contaminant mixtures in the marine environment.2 Effects of benzo(k)fluoranthene exposure on the biomarkers of scallop Chlamys farreriIn our experiments, we studied the effects of different concentrations of BkF (0.5 Pg/L, l.OMg/L, lO.OMg/L, 50. OUg/L) on EROD, GST, antioxidant enzymes and LPO in digestive gland and gills on scallop Chlamys farreri. Three replicates were designed for each treatment. The scallops are fed in plastic tanks (50cmX40cmX30cm), and the water was changed, in which the concentrations of BkF was maintained at the same level as designed.The sampling time was at 0, 0.5d, Id, 3d, 6d, 9d, 15d, 21d and 30d, respectively. The gills and digestive gland were placed under -20°C for the following measurement. The results showed that there had no effects on EROD activity in digestive gland at low concentrations (0.5Hg/L and l.OHg/L) of BkF, but it has increased the GST activity; but in high concentration (10. OUg/L and 50. OUg/L) of BkF, it has increased EROD activity significantly, otherwise, it has restrained the GST activity. From the results of antioxidant enzymes, we can see that the SOD, CAT and GPx activity in digestive gland increased significantly treated by low concentration of BkF (0. 5Hg/L and l.OHg/L), and it appeared time-effects and concentration-effects until it was stabilized at last. In high concentrations of BkF, the three antioxidant enzymes can increase and appears peak changes. In high concentrations of BkF, the activity of three antioxidant enzymes can increase significantly in short time (12h), then dropped under the controls at certain time. The activity in gills changed more significantly than in digestive gland. The LPO levels increased along with the sampling times, it appears time-effects and concentration-effects between MDA contents and BkF. From the results, the authors considered that the antioxidant enzymes changed more significantly than other enzymes and showed great orderliness, So they can be the biomarkers in evaluating the toxicity of BkF, LPO was a good supply in evaluating. However, we can see that the biomarkers determined in this experiments have the most important relationship in detoxification.3 Effects of benzo(a)pyrene and benzo(k)fluoranthene mixture on the biomarkers of scallop Chlamys farreriIn this experiment, we studied the effects of Benzo(a)pyrene and benzo(k)flouranthene mixture on EROD, GST, antioxidant enzymes activities and LPO levels of digestive gland and gills of scallop Chlamys ferrari. The results indicated that there had no effects on EROD activity in digestivegland at low concentrations (0. bMg/L and l.OHg/L) of PAHs, but it has increased the GST activity: but in high concentration (10. OUg/L and 50. OUg/L) of PAHs, it has increased EROD activity significantly, otherwise, the GST activity showed the peak changes, the three antioxidant enzymes all showed the peak changes and were restrained in high PAHs concentrations, gill was more sensitive to BaP than digestive gland, the gill' s detoxification function was less stronger than digestive gland, the digestive gland was the main tissue to deal with oxyradicals. The contents of MDA increased with the treating time and there had the positive correlation (concentration-effect) between the MDA contents and the concentrations of the BaP exposure. ? From our studies, we can see that the increase of EROD, the decrease of GST and the changes of antioxidant enzymes can reflect the toxicity of BaP, so the biomarker determined in this experiments showed the greatest utility as biomarkers of oxidative stress. The LPO was a direct biomarker reflecting the oxidant stress. The biomarkers determined in this experiments have the most important relationship in detoxification. 4 Responses of antioxidant systems and LPO level to benzo(a)pyrene and benzo(k)fluoranthene in the haemolymph of the scallop Chlamys ferrari In this experiment, we studied the effects of benzo(a)pyrene, benzo(k)flouranthene and their mixture on antioxidant enzymes activities and LPO levels of haemolymph of scallop Chlamys ferrari. The results showed that it was suitable to take the acetone group as controls. And in concentrations of 0. 5Mg/Land 1. OMg/L of each PAHs exposure groups, the SOD activity was higher than controls siginificantly (P<0. 05), but in BaP groups, the SOD activity was close to controls at last, the SOD changes in mixture groups was similar to that in BkF groups. In concentrations of 10. 0Mg/L and 50. 0Hg/L of each PAHs exposure groups, the SOD activities increased at first then dropped soon and were lower than controls significantly (P<0.05) at last. The GPx activities in each PAHs groups all increased significantly(P<0. 05), the concentration was higher, and the GPx activity was higher at same.sampling time. LPO levels all increased significantly (P<0.05) with the sampling time at each PAHs groups except the 0. 5Hg/L group of less than 12h. From our results, we can see that the toxicity level of BkF was lower than simplex BaP and the toxicity of BkF was similar to mixture of BaP and BkF. The authors concluded that the changes of antioxidant enzymes activities and LPO level in haemolymph could reflect the detoxification functions and damage levels of other tissues indirectly. The every biomarker determined in this experiments have most important relationships, the changes of the biomarker have the significant disciplinarian in detoxification.From the results mentioned-above, the authors think that the scallops can resist the damage done by PAHs of low concentrations, but it can be suffered from oxidative damage in PAHs of high concentrations, the biomarkers determined corperated in detoxification and had strong disciplinarian. The digestive gland is the main detoxification tissue, the damage of gills is most significant, the changes of antioxidant enzymes and LPO levels can reflect the functions of other tissues, it also reflected the detoxification functions of whole organism. The toxicity order of the PAHs is BaP>BkF>BaP and BkF mixture, the biomarkers determined in this experiment can be used to evaluate the PAHs toxicity. The authors deduced that PAHs toxicity for scallops relate to the constitution of PAHs, we can' t evaluate the PAHs toxicity with simplex PAHs exposure, this mainly relate to the detoxification mechanism of scallops, more should be studied in future.