Yin Xixiang, Wang Lihong, Zhang Zhanchao, Fan Guolan, Liu Jianjun, Sun Kaizhen, Sun Guo-Xin
Jinan Research Academy of Environmental Sciences, Jinan 250014, China.
Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China.
Int J Environ Res Public Health. 2017 Feb 14;14(2):188. doi: 10.3390/ijerph14020188.
, a freshwater protozoan, is common in aquatic systems. Arsenic detoxification through biotransformation by is important but poorly understood. Arsenic metabolic pathways (including cellular accumulation, effluxion, biomethylation, and volatilization) of were investigated at various phosphate concentrations. The total intracellular As concentration increased markedly as the external phosphate concentration decreased. The highest concentration was 168.8 mg·kg dry weight, after exposure to As(V) for 20 h. Inorganic As was dominant at low phosphate concentrations (3, 6, and 15 mg·L), but the concentration was much lower at 30 mg·L phosphate, and As(V) contributed only ~7% of total cellular As. Methylated As contributed 84% of total As at 30 mg·L phosphate, and dimethylarsenate (DMAs(V)) was dominant, contributing up to 48% of total As. Cellular As effluxion was detected, including inorganic As(III), methylarsenate (MAs(V)) and DMAs(V). Volatile As was determined at various phosphate concentrations in the medium. All methylated As concentrations (intracellular, extracellular, and volatilized) had significant linear positive relationships with the initial phosphate concentration. To the best of our knowledge, this is the first study of As biotransformation by protozoa at different phosphate concentrations.
作为一种淡水原生动物，在水生系统中很常见。通过其生物转化进行砷解毒很重要，但人们对此了解甚少。在不同磷酸盐浓度下研究了其砷代谢途径（包括细胞积累、外排、生物甲基化和挥发）。随着外部磷酸盐浓度降低，细胞内总砷浓度显著增加。在暴露于五价砷20小时后，最高浓度为168.8毫克·千克干重。在低磷酸盐浓度（3、6和15毫克/升）下，无机砷占主导，但在30毫克/升磷酸盐时浓度要低得多，且五价砷仅占细胞总砷的约7%。在30毫克/升磷酸盐时，甲基化砷占总砷的84%，其中二甲基砷酸（DMAs(V)）占主导，高达总砷的48%。检测到细胞砷外排，包括无机三价砷、甲基砷酸（MAs(V)）和二甲基砷酸（DMAs(V)）。在培养基的不同磷酸盐浓度下测定了挥发性砷。所有甲基化砷浓度（细胞内、细胞外和挥发的）与初始磷酸盐浓度均呈显著线性正相关。据我们所知，这是首次在不同磷酸盐浓度下对原生动物砷生物转化进行的研究。
