Study On Toxic Effect And Molecular Mechanism Of Petroleum Hydrocarbon Pollution To Hemicentrotus Pulcherrimus

Nowadays,oil pollution has threaten the marine environment all over the world and become one of the most serious pollution problems.Petroleum hydrocarbons are liable to deposition and accumulation,which leads to a higher level of oil contamination in the seabed.In this paper,model organisms-sea urchin,Hemicentrotus pulcherrimus was selected as test organism.The effects of petroleum hydrocarbon on the adult sea urchins and their embryos were studied from molecular level to explore the toxicity mechanism on aquatic life and to find suitable biomarkers for oil pollution detection. The main conclusions of the study are as follows:1.From the individual level,the acute toxicity effects of No.0 diesel water-accomodated fractions(WAFs) and dispersed No.0 diesel water-accomodated fractions(dis-WAFs) on sea urchin,Hemicentrotus Pulcherrimus was studied.The results show that:the 96h LC₅₀ value of No.0 diesel oil WAF and dis-WAFs are 5.1mg/L and 9.5mg/L respectively.The dis-WAFs is more toxic than WAFs.Gas chromatography-mass spectrometry analysis results show that the content of aromatic compounds in dis-WAFs is nearly 3 times of the latter.2.By using the method of static embryo toxicity test,sea urchin gametes and embryos were selected as experimental material and the effects of petroleum hydrocarbons on fertilization and embryos development were studied.The results show that petroleum hydrocarbon pollution decreased the fertilization ability of gametes.The inhibition degree is derectly proportional to the oil concentration.The 30minEC₅₀ for eggs decreased from 0.86mg/L to 0.36mg/L after adding dispersant into the WAFs,and 30minEC₅₀ for sperms decreased from 1.57mg/L to 0.38mg/L.Embryonic growth retardation,shorter body length,deformity and death can be observed in exposure experimental groups.The 48h and 72h EC₅₀ for No.0 dis-WAFs were 0.83mg/L and0.44mg/L;while the 48h and 72h EC₅₀ for No.0 oil diesel WAFs were 3.39mg/L and 1.87mg/L.The No.0 diesel dis-WAFs is obviously more toxic than WAFs.3.From an organizational level,the effects of No.0 diesel WAFs on the antioxidant defense system and lipid peroxidation of Hemicentrotus pulcherrimus after low-dose exposure were investigated.The results show different distributions of antioxidant enzyme activity in Hemicentrotus pulcherrimus.The dose-effect and time-effect relations were between the biochemical response and petroleum hydrocarbon pollution. The time-effect pattern of antioxidant defense system follows the law of increasing first and then decreasing.GSH has been gradually reduced because of the consumption and lipid peroxidation intensified by prolonging the exposure time and increasing exposure dose.GST activity is the most sensitive to petroleum hydrocarbon pollution and is more suitable to be the biomarker for monitoring and testing the extent of petroleum hydrocarbon contamination in the seabed.4.From the molecular level,complement C3 gene mutation was detected through PCR-SSCP technique and sequence determination.The results suggest that single base mutation has taken place in coding region of the 1184,with the conversion of C→T, where amino acid changed from threonine into isoleucine.Hox1 gene mutation detection results show that single base mutation have taken place in coding region of the 184,with the conversion of T→C,where amino acid is changed from serine into proline.It is also observed that with the extension of exposure time and concentration, mutation rate increased gradually.5.From the molecular level,the globle genomic DNA was detected by high performance liquid chromatography.The results show that there are no significant dose-effect relationship and with the time prolonging,hypomethylation happens under the exposure.It suggests that methyltransferase activity in sea urchin is inhibited after petroleum hydrocarbon exposure.The exposure can not only produces genetic toxicity effects,but also change the DNA methylation level.