Sargassum fusiforme (hijiki) is a popular edible seaweed in some Asian countries. However, it has been shown to have high concentrations of arsenic, mainly the more toxic inorganic arsenic. In this study, we determined the concentration, species, distribution, and absorption kinetics of arsenic (As), and the influence of different exogenous substances on its absorption. Arsenic content in the mature stage of hijiki reached up to 84.37 mg/kg dry weight. Inorganic arsenic (iAs) accounted for 68% of the total arsenic, while Arsenate (As (Ⅴ)) accounted for more than 50% of total inorganic arsenic. The contents of arsenic in different hijiki organs decreased in the following order rhizoid stem leaf airbag. Subcellular distribution of arsenic in untreated hijiki decreased in the order: cell walls cell organelles cytoplasm. In hijiki, arsenate had a higher absorption rate than arsenite (As (III)), with Vmax and km about 2 times and 3 times those of As (III), respectively. The absorption of As (V) was inhibited by phosphorus, but was not affected by glycerol. The opposite was true in the case of As (III) adsorption. Sodium vanadate significantly increased the efflux of As (V), but had no effect on As (III). Carbonylcyanide-pchlorophenyl hydrazone (CCCP) and glycerol inhibited the arsenite efflux, but had no influence on arsenate.
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