Subcellular Distribution and Mechanism of Detoxifying Arsenic in Porphyra Yezoensis
In order to disclose the compartmentation of arsenic and the mechanism of detoxifying arsenic in Porphyra yezoensis,the transformation of different arsenic speciation and the subcellular distribution of arsenic in P. yezoensis were conducted. The seaweed was exposed to different concentrations( 0. 05,0. 1,0. 5 and1. 0 mg / L) of arsenite( As(Ⅲ)) and arsenate( As(Ⅴ)) for 6 days. Samples were randomly collected every day.The arsenic speciation in P. yezoensis was analyzed using HPLC-ICP-MS and the subcellular distribution of arsenic was conducted using differential centrifugation. Results showed that the arsenic accumulated in the seaweed increased with the exposed concentration and exposure time increasing. A clear dose-response was proved to exist in both As(Ⅲ) and As(Ⅴ) exposure,and the correlation coefficient was 0. 9996( p 0. 01) and0. 9844( p 0. 01) for As(Ⅲ) and As(Ⅴ) respectively. In addition,the accumulation rate of As(Ⅲ) was higher than that of As(Ⅴ),and the accumulation coefficient of arsenic was 4719 and 4112 respectively for the seaweed exposed to 0. 1mg / L As(Ⅲ)and As(Ⅴ) after 6ds exposure. The results also proved that there was a great difference in the different subcellular distribution and the compartmentation of arsenic in P. yezoensis. The sequcence of different subcellular distribution was cyplasmic supernatant( 80%) cell wall( 15%) cell organelles( 5%). Cyplasmic supernatant was the main localization for arsenic and played an important role in the compartmentation of As. At the same time,the research of the arsenic transformation during accumulation showed that the absorbed As(Ⅴ) in P. yezoensis would be quickly methylated and then be transformed to arsenic sugar( AsX1); the absorbed As(Ⅴ) in P. yezoensis would be firstly reduced to As(Ⅲ),which was then be methylated and transformed to arsenic sugar( AsX1). The ability of the compartmention and the transformation of different arsenic speciation in P. yezoensis may play a key role in detoxifying arsenic.