Toxic Effects And Mechanisms Of 2,2',4,4'-tetrabromodiphenyl Ether (BDE-47) On Qingping

In order to understand the toxic effects and mechanism of 2,2',4,4'-tetrabromodiphenyl ether?BDE-47?on aquatic plants,Lemna minor L.was used as the research object.The effects of different concentrations of BDE-47 on the toxicity and mechanism of L.minor were studied systematically from the aspects of population growth,photosynthetic function,antioxidant capacity and cells.These results turn out:1?Effects of BDE-47 on physiological and biochemical indexes of L.minor?1?Effects of BDE-47 on the biomass and root length of L.minor:Under specific environmental and nutritional conditions,the growth of L.minor biomass per unit area was constrained by density,and the growth curve of L.minor biomass with time had a"S"type,which indicated that the growth curve of L.minor was in accordance with the typical Logistic growth model.BDE-47 treatment significantly inhibited the growth of L.minor and inhibited the growth of roots with the concentration of 5?g/L.At the same time,BDE-47 had no significant effect on the root length of L.minor when the concentration was between 5 and 20?g/L.?2?Effects of BDE-47 on Chlorophyll and Protein Content of Chloropyll:The content of chlorophyll and soluble protein decreased with the increasing of BDE-47concentration.The lowest chlorophyll content was 5.25 mg/g?FW?after treatment with 20?g/L BDE-47,and the soluble protein content was only 34.0%of the control.2?Effects of BDE-47 on photochemical activity of L.minor?1?Effects of BDE-47 on the long-term action of photosynthetic membrane of L.minor:With the increase of BDE-47 concentration,Fv/Fm and PI decreased significantly.Fv/Fm decreased to 0.641 after treatment with 20?g/L BDE-47 for 14days and decreased to 43.4%,32.7%,26.5%and 10.4%respectively.After 14 days of treatment with 5,10,15 and 20?g/L BDE-47.?2?The direct effect of BDE-47 on the photosynthetic membrane of L.minor was similar to that 14 days treatment of BDE-47.The results showed that with the increase of BDE-47 concentration,the Fv/Fm and PI showing a significant downward trend.3?Effects of BDE-47 on permeability of plasma membrane of L.minor?1?The long-term effects of BDE-47 on plasma membrane permeability of L.minor:After 14 days of treatment with BDE-47,plasma membrane permeability increased significantly with increasing concentration,plasma membrane permeability is 3 times of the control,especially 20?g/L BDE-47?2?The direct effect of BDE-47 on the plasma membrane permeation of L.minor:It was similar to that long-term effects of BDE-47.The results showed that BDE-47showed a significant increase in plasma membrane permeability with the increase of BDE-47 concentration.4?Effects of BDE-47 on antioxidant enzymes and redox balance of L.minor?1?Effects of BDE-47 on the antioxidant enzymes of L.minor:With the increase of BDE-47 concentration,the activity of SOD increased significantly and the activities of POD and CAT exhibited a parabolic trend with the increase of BDE-47concentration.?2?Effects of BDE-47 on the redox balance:As the concentration of BDE-47increased,the content of O₂ and MDA of L.minor were increased significantly.5?Effects of BDE-47 on the activity of PBDEs degradation Enzymes of L.minorWith the increase of BDE-47 concentration,the activity of GST was almostunchanged and NR activity increased slightly.6?Effects of BDE-47 on cytoplasmic enzyme activityWith the increase of BDE-47 concentration,the activity of NR and POD of L.minor was almost unchanged.7?Effects of BDE-47 on submicron microstructure of L.minor5?g/L BDE-47 resulted in severe structural deformation of the cells,even chloroplast dissolution and severe wall separation.The cell damage was more serious under 20?g/L BDE-47 treatment.