| PAHs (polycyclic aromatic hydrocarbons, PAHs) are a class of compounds,containing two or more benzene rings. They are a wide range of sources, stability and three-induced effects on the human body.As a persistent organic pollutants (POPs) Environmental Monitoring They were considered as an important class of research in recent years, often as a hot research field of the environment at home and abroad. In this paper,we have studied the toxicity of polycyclic aromatic hydrocarbons benzo[a]pyrene in the Phaeodactylum tricornutum which was widely represented in the laboratory and has been reaseached last year.We deepen the research about the toxicity.1.We studied the reasons of strong tolerance of Phaeodactylum tricornutum, by high-performance liquid chromatography. Biological stress concentration stress group and abiotic stress experiments has been applied in high 700μg/L and low 100μg/L dose of benzo[α]pyrene, to understand algae adsorption and metabolism of benz o[α]pyrene, by changes of benzo[α]pyrene in the medium. It was found that the total content of benzo[α]pyrene medium has a lowering phenomenon, but this reduction is slow, and similar to the non-biological control group,so we found the benzo[α]pyrene degradation from light degradation, and has a little relation about detoxification in Phaeodactylum tricornutum. However, in the water of Phaeodactylum tricornutum culture, the content of benzo[α]pyrene had quickly reduce.Compared with the control group of non-biological,by one day, benzo[a]pyrene concentrations in the Phaeodactylum tricornutum culture were reduced by 92.3% and 89.3%.Through the study of algae benzo[a]pyrene content,we found this rapidly reduce was concerned with its adsorption, Phaeodactylum tricornutum did not have a strong ability to metabolize benzo[α]pyrene.The weak capability of detoxification is the reason why they can face less oxidative stress which generated in the process of secondary metabolites.2. We research the benzo[α]pyrene (B [α] P) effects on algal density and.by flow cytometry method.detect the effects of changes in chlorophyll content in living cells. Though the reaserch we found that at high concentrations of benzo[a]pyrene 700μg/ L stress, where 96 hours inhibition of cell density is 43.1%, the chlorophyll transfer receiving material is not significant impact on important intracellular energy, its content in four consecutive days, three The next dose had no significant change in the content of the cell contents.Although increased compared with the control group, these does had not induce significant levels, Phaeodactylum tricornutum were able to maintain basic life activities at such a high concentration of benzo[a]pyrene environment.3.Further experiments with activity of detoxification enzyme and the corresponding differential gene expression analysis were done. And a antioxidant important system of Phaeodactylum tricornutum for plant cells,ascorbate glutathione cycle, as well as the expression of the enzyme superoxide dismutase SOD gene were analysised. The results found that the metabolic detoxification enzymes genes and antioxidant SOD genes showed similar changes to its enzyme activity, has increased following with increasing concentration and time. Although detoxification is not strong, the metabolism has been stronger. Secondary metabolites by the metabolism of the cells produced oxidative damage,and antioxidant mechanisms start quickly. SOD gene induced significantly higher and enzymes and nonenzymes in ascorbic acid-glutathione cycle system play an important role.Along with benzo[a]pyrene concentrations increase and prolong stress time, benzo[a]pyrene on Phaeodactylum growth inhibition gradually increased and malondialdehyde (MDA) in the algal cells and total antioxidant capacity (TAOC) had significantly increased,which we found has a correlation coefficient to the stress intensity 0.960,0.894.While, AsA-GSH cycle in non-enzymatic ingredients ascorbic acid (AsA), glutathione (GSH) content increased, the related enzyme glutathione reductase (GR), ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR) and a single hydrogen ascorbic acid reductase (MHAR) had a general increase in activity, in which GSH content. GR. APX and DHAR activity had a correlation coefficient to MDA content 0.744,0.852,0.652.0.600 t. The results illustrate that AsA-GSH cycle is important to Phaeodactylum against stress benzo[a]pyrene,quenching of reactive oxygen species.and reducing membrane lipid peroxidation. AsA content,GR activity and APX activity in benzo[a]pyrene stress responsion changed significantly,which could be considered the potential biological indicators.4. Finally experiments analyzed oxidative damage result from benzo[a]pyrene, under the stress we found high concentrations of benzo[a]pyrene oxidative stress lead to lipid peroxidation damage.Compared with the control group, intracellular MDA in experiment group had a significant difference, there are increases tendency along with the time and dose increases. In contrast,that the DNA damage which were lead by benzo[a]pyrene was not obvious. Although there is some influence than the control group, but did not reach significant levels. We concluded oxidative damage mainly occurs in the cytoplasmic matrix of Phaeodactylum tricornutum. |
PDF Full Text Request