| PAHs (Polycyclic Aromatic Hydrocarbons)are one kind of persistent organic pollutants in the environment, which have effects of carcinogenesis, teratogenesis and mutagenesis. The problem of PAHs pollution in marine is getting seriously, and the research on toxicity of PAHs to marine organisms is highlighted. In this paper, We studied the effects of phenanthrene(PHE) and benzo[b]fluoranthene(BbF) on the activities of antioxidantive enzymes (SOD,CAT, GPx), nerveaction enzyme(AChE), metabolic enzymes (EROD, GST) and the expression of CYP1A mRNA of green-lipped mussel (Perna viridis), crimson snapper (Lutjanus erythropterus) and river snapper (Lutjanus argentimaculatus),in addition, we also utilize histological section to estimate the tissue damage of Lutjanus erythropterus by PHE. Then we got the index of tested animals after PAHs exposure and eliminate in water, and explored their indicating function to PAHs pollution. The results are as following:1. The toxicological effects of PHE and BbF on the tissue of Perna viridisUnder the exposure of PHE, CAT activity in viscera of Perna viridis was induced during the first day. The SOD activity was firstly induced and then restrained in the viscera and mantles. The GPx activity in viscera followed the same pattern as that of SOD. Under BbF exposure, the three antioxidant enzymes were induced at the concentration of 2.0μg·L-1 in the early exposure period, and CAT activity reach the peak after 4 d's exposure, with which the inductivity was 81.9%. SOD activity followed a restrained-induced-restrained trend at the concentration of 10.0μg·L-1 and 50.0μg·L-1 , and the inductivities were 24.9% and 62.3% respectively, for 8 d's exposure. While GPx activity followed a restrained-induced trend, and the restrainion ratio reached 23.4% and 28.9%, respectively, at the concentration of 10.0μg·L-1 and 50.0μg·L-1 . The contents of MDA were increasing increased during the whole exposure period of PHE and BbF, indicated the oxidative stress by PHE and BbF. During the elimination period, the activities of most antioxidant enzymes resumed, which indicated that the mussel can recover from a certain degree of PAHs stress. There is a linear relationship between the exposure time and the effects; meanwhile CAT can be used as the early warning to the PAHs stress. The results showed that SOD, GPx, MDA could be utilized for indicators of the effects by PHE and BbF exposure.2. The toxicological effect of PHE on the tissue of Lutjanus erythropterusUnder the exposure of PHE, the median lethal concentration(LC50) of Lutjanus erythropterus for 24 h, 48h and 96h were 4.65, 3.46, 3.17 mg·L-1 , respectively. SOD activities in the liver and gills increased under a concentration of 10.0μg·L-1 . Under the exposure concentration of 50.0 and 250μg·L-1 , it was firstly restrained and then induced in the liver. However, it followed the restrained-induced-restrained trend in gills. The MDA content in the liver and gills has been increasing with time going on. This also indicated that the degree of injury raised. AChE activity in brain was induced under low concentration of PHE. However, it was restrained with higher concentration which indicated that PHE exposure has harmful effects to neurotransmission in fish brain. The results suggested that the PHE has a high toxical effect on L. erythopterus.SOD, AChE activities and MDA contents were suitable to be bio-indicators for the PHE pollution because of their high sensitivities.3. The toxicological effect of PHE on the tissue of Lutjanus argentimaculatusUnder the exposure of PHE, the index changed significantly, including: (1) GST activities in liver and gills are both induced by 10.0μg·L-1 concentration exposure, meanwhile it was induced fist and then restrained with 50μg·L-1 and 250μg·L-1 exposure, and GST activities decreased more quickly in gills. (2) EROD activities in the liver were induced in the earlier period of 3 d, but restrained at 15 d. In the contrast, it significantly varied and followed an induced-restrained-induced trend in gills. This may resulted from the longer time of gills exposed to PHE. (3) The results of molecule experiment suggested that PHE can induce the expression of CYP1A mRNA in liver and gills. However, the expression decreased with increasing of exposure time. (4) The changes of EROD activity were in accordance with that of CYP1A expression in liver. Whereas, this was not observed in gills. This may due to that the changing of EROD activity must go through mRNA transcription and expression. Further studies were needed to clarify the possible reasons. |
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