Miyashita Shinichi, Fujiwara Shoko, Tsuzuki Mikio, Kaise Toshikazu
School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Tokyo, Japan.
Biosci Biotechnol Biochem. 2011;75(3):522-30. doi: 10.1271/bbb.100751. Epub 2011 Mar 7.
We examined the short-term metabolic processes of arsenate for 24 h in a freshwater unicellular green alga, Chlamydomonas reinhardtii wild-type strain CC-125. The arsenic species in the algal extracts were identified by high-performance liquid chromatography/inductively coupled plasma mass spectrometry after water extraction using a sonicator. Speciation analyses of arsenic showed that the levels of arsenite, arsenate, and methylarsonic acid in the cells rapidly increased for 30 min to 1 h, and those of dimethylarsinic acid and oxo-arsenosugar-glycerol also tended to increase continuously for 24 h, while that of oxo-arsenosugar-phosphate was quite low and fluctuated throughout the experiment. These results indicate that this alga can rapidly biotransform arsenate into oxo-arsenosugar-glycerol for at least 10 min and then oxo-arsenosugar-phosphate through both reduction of incorporated arsenate to arsenite and methylation of arsenite and/or arsenate retained in the cells to dimethylarsinic acid via methylarsonic acid as an possible intermediate.
我们研究了淡水单细胞绿藻莱茵衣藻野生型菌株CC-125中砷酸盐24小时的短期代谢过程。使用超声仪进行水提取后，通过高效液相色谱/电感耦合等离子体质谱法鉴定藻类提取物中的砷物种。砷的形态分析表明，细胞中亚砷酸盐、砷酸盐和甲基砷酸的水平在30分钟至1小时内迅速增加，二甲基砷酸和氧代砷糖甘油的水平在24小时内也趋于持续增加，而氧代砷糖磷酸的水平相当低且在整个实验过程中波动。这些结果表明，这种藻类可以在至少10分钟内将砷酸盐迅速生物转化为氧代砷糖甘油，然后通过将摄入的砷酸盐还原为亚砷酸盐以及将细胞中保留的亚砷酸盐和/或砷酸盐通过甲基砷酸作为可能的中间体甲基化为二甲基砷酸，转化为氧代砷糖磷酸。
