Marine animals, arsenic

C. Marine Animals Toxicological Considerations Biotransformation of Marine Arsenic Compounds... 

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...

Arsenobetaine was the first arsenic compound identified in a marine animal when it was isolated in 1977 in a crystalline form from the tail muscle of the western rock lobster Panulirus cygnus (48). The large body of work that followed established that arsenobetaine was by far the predominant form of arsenic in marine animals (Table VI). It occurs at all trophic levels, although there is a tendency for it to be present at higher concentrations (or at least constitute the greater percentage... 

Inorganic arsenic is a minor component in marine animals, generally constituting less than 2% of the total arsenic (109). 

The application of high-sensitivity ICP-MS detectors coupled to HPLC has enabled the detection of trace arsenic compounds present in marine animals. Thus, arsenocholine has been reported as a trace constituent (<0.1% of the total arsenic) in fish, molluscs, and crustaceans (37) and was found to be present in appreciable quantities (up to 15%) in some tissues of a marine turtle (110). Earlier reports (46,47) of appreciable concentrations of arsenocholine in some marine animals appear to have been in error (32). Phosphatidylarsenocholine 45 was identified as a trace constituent of lobster digestive gland following hydrolysis of the lipids and detection of GPAC in the hydrolysate by HPLC/ICP-MS analysis (70). It might result from the substitution of choline with arsenocholine in enzyme systems for the biogenesis of phosphatidylcholine (111). 

In metabolic studies with animals it is often difficult to distinguish between processes carried out by the animal and those performed by resident microorganisms, such as the gut microflora. In the following, the transformations refer to those taking place within the marine animal, whether microbially mediated or otherwise. Metabolic studies with marine animals are faced with further complications because water can be an important uptake route. A chemical, in this instance arsenic in its various forms, may undergo microbial conversions in the water, and the resultant metabolites may be accumulated by the marine animal. Thus, careful experimentation may be required to determine what is occurring inside rather than outside the animal. 

C. Rojima, T. Sakurai, M. Ochiai H. Rumata, W. Qu, M. P. Waalkes, R. Fujiwara, Cytotoxicological aspects of the organic arsenic compound arsenobetaine in marine animals, Appl. Organomet. Chem., 16 (2002), 421-426. 

R. Rubota, T. Runito, S. Tanabe, Chemical speciation of arsenic in the livers of higher trophic marine animals, Mar. Pollut. Bull., 45 (2002), 218-223. 

J. Kirby, W. A. Maher, Measurement of water-soluble arsenic species in freeze-dried marine animal tissues by microwave-assisted extraction and HPLC-ICP-MS, J. Anal. Atom. Spectrom., 17 (2002), 838-843. 

The leaching of arsenic forms is usually performed from soil or from tissues of plants or marine animals. The extraction of materials of biological origin typically involves methanol or mixtures of methanol and water. Solutions obtained by centrifugation and filtration are diluted with water and then loaded into an ion-exchange column. The method is applied for assay of arsenic acid salts and arsenosugars, even though they are more easily soluble in water than in methanol. This method of extraction into a solution involves transfer of a smaller quantity of toxic As(III) and As(V) salts than methylated derivatives and AsB or AsC, which are of markedly lower toxicity [88]. 

Cullen and Reimer summarized data on organoarsenicals isolated from seventy-two marine animals and their organs. According to their data, the arsenic concentrations range... 

Arsenic compounds were determined in the marine lungworm Arenicola marina collected from Odensee Fjord, Denmark [159]. In contrast to most other marine animals, A. marina contained most water-soluble arsenic in inorganic forms, and arsenobetaine 54 was present as a minor constituent (6% only). Other arsenic compounds detected in A. marina were dimethylarsinate 47 (4%), tetramethylarsonium ion 53 (1.5%), arsenocholine 55 (<1%), and two arsenosugars (56, 57, 1% and 3%, respectively). A new arsenobetaine, i.e. trimethylarsoniopropionate (62), previously only reported in fish, was also present in trace amounts (<1%). 

Hanaoka K, Goesslee W, Ohno H, Irgolic KJ and Raise T (2001) Formation of toxic arsenical in roasted muscles of marine animals. Appl Organo-met Chem 15 61-66. 

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