Marine algae, arsenic

Marine algae transform arsenate into nonvolatile methylated arsenic compounds such as methanearsonic and dimethylarsinic acids (Tamaki and Frankenberger 1992). Freshwater algae and macrophytes, like marine algae, synthesize lipid-soluble arsenic compounds and do not produce volatile methylarsines. Terrestrial plants preferentially accumulate arsenate over arsenite by a factor of about 4. Phosphate inhibits arsenate uptake by plants, but not the reverse. The mode of toxicity of arsenate in plants is to partially block protein synthesis and interfere with protein phosphorylation — a process that is prevented by phosphate (Tamaki and Frankenberger 1992). 

Yamaoka, Y. and O. Takimura. 1986. Marine algae resistant to inorganic arsenic. Agric. Biol. Chem. 50 185-186. 

Although there had been earlier reports (1-3) of the presence of arsenic in marine samples, the first comprehensive study was presented by Jones (4) in 1922. He examined marine algae collected from British coastal waters, reporting concentrations of arsenic and information on its extraction with water and ethanol. He referred to the arsenic as organic arsenic and, perhaps somewhat mischievously, remarked that the reputed medicinal properties of some algae may be due to their organic arsenic content. 

Tables I to III provide a summary of some representative data for total arsenic concentrations in sediments, marine algae, and marine animals. There can be considerable variation in the arsenic levels in these samples, in contrast to the levels in seawater, which are reasonably uniform in the world s oceans at about 0.5-2 /ug/liter (9,10). For sediments, there is perhaps a tendency for arsenic concentrations to be lower in samples from coastal regions and estuaries compared with deep-sea sediments. Industrial discharges of arsenic-enriched effluents can, however, result in arsenic contamination of near-shore sediments...

Arsenic concentrations in marine algae are generally considerably higher in brown algae than in either red or green algae. Reasons... 

Arsenic-Containing Compounds from Marine Algae... 

The arsenic constituents of marine algae have been the subject of several detailed studies over the past 15 years. It is of interest that arsenobetaine, arsenocholine, TMAO, and TeMA are yet to be detected in marine algae. 

Marine algae as well as some higher aquatic plants detoxify and excrete arsenate by conversion to various water-soluble organic forms such as trimethyarsonium lactic acid (Chapter 8) and the following ribofuranoside.3... 

The absorption of arsenic by marine algae has been referred to (p. 18) certain Chinese medicinal algae have an exceptionally high arsenic content.9... 

Aridreae, M. O., and Klumpp, D. (1979). Biosynthesis and release of organo-arsenic compounds by marine algae. Environ. Sci. Technol. 13, 738-741. 

The marine environment is a vast resource for the discovery of structurally unique bioactive secondary metabolites, some belonging to totally novel chemical classes.8 Sessile benthic organisms including the Porifera, Cnidaria, Bryozoa, and Tunicata as well as marine algae have developed an arsenal of compounds which have been demonstrated to confer a competitive advantage in ecosystems characterized by extreme resource limitations. Interactions of these organisms at the genetic,... 

T. Raise, Y. Oya-Ohta, T. Ochi, T. Okubo, R. Hanaoka, R. J. Irgolic, T. Sakurai, C. Matsubara, Toxicological study of organic arsenic compound in marine algae using mammalian cell culture techniques, J. Food Hyg. Soc. Jap., 37 (1996), 135-141. 

Andreae, M.O. 1978. Distribution and speciation of arsenic in natural waters and some marine algae. Deep-Sea Res. 25 391-402. 

Karthikeyan, S., Hirata, S., Honda, K., Shikino, O. Speciation of arsenic in marine algae and commercial shrimp using ion chromatography with ICP-MS detection. At Spectrosc 2003, 24, 79-88. 

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