The Toxic Mechanism Of N-Phenyl-2-Naphthylamine To Chlorella Vulgaris

In recent years,eutrophication of water systems has been a global issue.The increasingly serious eutrophication causes water pollution and can effect human health by enhancing the growth of algal blooms which can release toxins.The traditional methods of inhibiting the growth of algal exist some defaults in diffenent degrees such as high cost,producing ecological risk,and hard to control.All these limited their use.The using of allelopathy and allelochemical can control the growth of algal with the rapid of chemical methods and the safety of biological methods.We choosed N-phenyl-2-naphthylamine as allelochemical and Chlorella vulgaris as experimental objects,through the changes of antioxidant enzyme activity and mRNA abundance levels to study the toxic mechanism of allelochemicals.In order to identify the mechanism of allelochemical in molecular level,We selected three heribicides atrazine,diclofop-methyl and glufosinate to establish the Real-time PCR for analyzing mRNA abudance in Chlorella vulgaris.The Real-time PCR showed that after 16h the three herbicides reduced the transcription abundance of psbC and rbcL to 25.6%,51.7%,29.1%and 6%,21%,7%of the control, respectively.The Real-time PCR assay was specificity.For the purpose of detecting the relationships between the algal cell concentration and the toxic of N-phenyl-2-naphthylamine,three different initial stages of Chlorella vulgaris was selected.The results indicated that in the same concentration of N-phenyl-2-naphthylamine,the inhibition of growth was more obviously in the smaller initial stage.This suggested that the effects of allelochemicals were related to the growth cycle of algae.Based on these experiments,we choose the initial stage of exponential growth phase,2.5mg/L and 4mg/L N-phenyl-2-naphthylamine,to study the effects from the ultrastructure, chlorophyll level,changes of antioxidant enzyme activity(SOD,POD, CAT),and lipid peroxidation level.The results showed that N-phenyl-2-naphthylamine can damage the cell integrity and decrease the chlorophyll level significantly,trigger the production of Reactive oxygen species,lead to the increased lipid peroxidation level.For the further study,we used Real-time PCR to analyze the mRNA abundance level of photosynthesis related genes psaB,psbC and rbcL. Exposured to 2.5mg/L N-phenyl-2-naphthylamine reduced the transcruption abundance of psaB and psbC seriously.However,at 4mg/L N-phenyl-2-naphthylamine,transcription abundance of psaB and psbC increased after 6h and 12h exposure,and then quickly decreased after longer exposure.The transcription abundance of rbcL were not changed obviously.So N-phenyl-2-naphthylamine mainly affects the light reaction process and inhibits the effects of photosynthesis.This topic mainly study through physiological mechanism and transcription abundance of genes related photosynthesis.These will provide certain theoretical basis about the further study of allelochemicals and the search of new anti-algal drugs.