| A large number of oil as a globall energy applied to the actual produc-tion and life, the marine environment of petroleum hydrocarbon pollution isincreasingly serious in recent years, because of marine oil exploitation andtransportation accidents.besides, the rapid development of marine transporta-tion, serious emissions of industry and life sewage cause more pollution inmarine, even a threat to marine life. At present, more and more scholars de-vote themselves to the protection of marine ecological environment; theseissues are also studued in this paper. Under the condition of semi-hydrostaticsimulation, green mussels (Perna viridis) were exposed to0.005,0.010,0.050,0.100mg/L NO.0diesel oil water-soluble fraction (WSF) for1,3,7and15days. After15days, P. viridis in each concentration group weretransferred into clean sea water for7days, and samples were collected in18and22days after WSF were removed. Toxicological effects、relative level ofCYP4gene expression、DNA damage、Petroleum hydrocarbons enrichmentand microscopic observation of gill structure in P. Viridis were examed,Acrroding to these analyses, we Purpose to explore the antioxidant defensesystem and molecular toxicity mechanism of P. Viridis in the stress of WSF.It’s also to provid the basic datas for marine environment protection and ma-rine environmental biological monitoring.1. Toxicological Effects of Petroleum Hydrocarbons on Green Mussel (Pernaviridis)The malondialdehyde (MDA) and glutathione (GSH) contents, superox-ide dismutase (SOD) and glutathione S-transferase (GST) activities in the visceral mass and mantle of P. viridis were investigated as possible bi-omarkers of environmental petroleum hydrocarbons contamination in thecoastal area. The results showed that, the SOD activity and MDA content invisceral mass and mantle were more significant affected by the high concen-tration (0.100,0.050mg/L) of petroleum hydrocarbons than that in the lowconcentration group (0.005mg/L)(P<0.01). The SOD activity and MDAcontent followed a restrained-induced-restrained trend in the period of expo-sure, and there was no significant relationship among the concentration ofpetroleum hydrocarbons, exposure time and their effects. The GSH contentand GST activity in visceral mass tissues were sensitive to changes in con-centration of petroleum hydrocarbons and inhibited in the early exposure.Then the GSH content and GST activity in visceral mass were induced a sig-nificant increase (P<0.01) and reached the maximum after7days exposure.The GSH content and GST activity in the mantle of P. viridis put up a trendof ebb and flow. There was a linear relationship between the concentration ofpetroleum hydrocarbons and the exposure time. The content of MDA andGSH and the activities of SOD and GST in the visceral mass and mantle of P.viridis returned to the level of the control groups gradually after petroleumhydrocarbons were removed.2．The effect of CYP4gene expression exposed to Petroleum hydrocarbonon Green mussels (Perna viridis)The CYP4gene expression level in the visceral mass and mantle of P.viridis were investigated as possible biomarkers of environmental petroleumhydrocarbons contamination in the coastal area. The CYP4gene expressionlevel of treat groups were obviously higher than control group in initial pe-riod, it showed a slowly trend to increase. The induced effects maintained3-5days, it appeared induced effect saturation and the restrained effect of0.005mg/L concentration group was obvious. The CYP4gene expression level inthe visceral mass and mantle of P.viridis followed an in- duced-restrained-induced trend with the exposure time increasing, at thesame time, the CYP4gene expression level in the mantle mass showed a cer-tain relationship between the concentration of petroleum hydrocarbons andthe exposure time. The CYP4gene expression level in the visceral mass wereobviously higher than mantle, the0.050mg/L concentration group was sig-nificant difference. The CYP4gene expression in mantle of0.010mg/L and0.005mg/L did not return to the level of the control groups with significantdifferences after petroleum hydrocarbons were removed（P<0.01），but theother groups had no significant differences.3. The DNA damage of Green mussels (Perna viridis) exposed to Petro-leum hydrocarbonsUsing alkaline unwinding assay, we exam the level of DNA damage anddouble strain breakage in visceral mass, mantle, gill tissue and gonad underthe stress of WSF. The resluts show that WSF remarkably induced DNAdamage, it shows time depended concentration effects (P<0.01). In WSFex-posure time, DNA fracture were induced obviously in various tissues withinfirst day, DNA damages in visceral mass and mantle reached maximum valueat the time of third day during WSF exposure, then DNA repair system wereactived to work with the negative effect of WSF accumulation after third day.DNA damage in gill was impacted hardly at seventh day, after that DNA wasrepaired gradually. Different from any other tissues, gonad’s DNA weredamaged seriously at first day, after a interval time to repair, it were de-stroyed again in the next four days to maintain a basic levels of Petroleumhydrocarbons in Green mussels.During the period of exposure, DNA fluctua-tion changes were happened with the time extended, it shows the relativitybetween accumulation time and effects. 4. The study of enrichment effect on Petroleum hydrocarbons in Greenmussels (Perna viridis).In order to test the enrichment amounts of Petroleum hydrocarbons ofsoft tissue in Green mussels by national standard assay, we hope to investi-gate the capacity of Petroleum hydrocarbons enrichment or purification inGreen mussels at different situation.The results show the exsistence of Pe-troleum hydrocarbons enrichment in soft tissue in Green mussels at four di f-ferent concentrations. In the group of0.005mg/L, the concentration of P e-troleum hydrocarbons gets into the stage of dynamic balance at first threedays. meanwhile, the concentration of Petroleum hydrocarbons in soft tissuesin the groups of0.001mg/L、0.050mg/L and0.100mg/L were leaped to in-crease. On the third day, the enrichment amount of Petroleum hydrocarbonsin soft tissues is proportional to exposure concentration.With different con-centration of WSF pollution, the Green mussels selectively enriched Petro-leum hydrocarbons.The procedure of Petroleum hydrocarbons depuration ingreen mussels firstly realeased rapidly, then gradual realeased to the stage ofdynamic balance at22day.5. Microscopic observation of gill structure exposed to Petroleum hy-drocarbons in Green mussels (Perna viridis).We had used the paraffin section technology to observe the cellstructure changes of gill in green mussels, which were exposed to0.005,0.01,0.05,0.1mg/L NO.0diesel oil water-soluble fraction (WSF) for1,3,7and15days. After15days, P. viridis in each concentration group were transferredinto clean sea water for7days, and samples were collected in18and22daysafter petroleum hydrocarbons were removed. In the WSF realease stage of18th and22nd day, we analysed the cell structure changes in gill on the con-dition of different WSF exposure concentration.The results shows that WSFhave strong toxicity on structure of green mussels gill, the different concen-tration have different effects, the epithelial cells in gills arranged irregularityeven break up, microvilli cells distort and abscisic at the top, square cells autolysis in high concentration. At the stage of WSF pollution realease, gillcells were not repaired to reflects the destroy effect on petroleum hydrocar-bons pollution. |
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