Azaspiracid accumulation in Japanese coastal bivalves and ascidians fed with Azadinium poporum producing azaspiracid-2 as the dominant toxin component. (April 2023)

• Record Type: Journal Article
• Authors: Ozawa, Mayu; Uchida, Hajime; Watanabe, Ryuichi; Matsushima, Ryoji; Oikawa, Hiroshi; Takahashi, Kazuya; Iwataki, Mitsunori; Suzuki, Toshiyuki
• Is Part Of: Toxicon. Volume 226(2023)
• Publication Date: 2023-04
• Subjects: Ascidians -- AZA accumulation -- Azaspiracids -- Azadinium poporum -- Bivalves -- Tissue distribution; AZA azaspiracid -- LC-MS/MS liquid chromatography-tandem mass spectrometry -- SRM selected reaction monitoring; Toxins -- Periodicals; Venom -- Periodicals; 615.9
• DOI: 10.1016/j.toxicon.2023.107069
• Languages: English
• ISSNs: 0041-0101

Abstract

Abstract: The filter-feeding bivalves often accumulate marine toxins by feeding on toxic dinoflagellates that produce marine toxins. Azaspiracids (AZAs) are a group of lipophilic polyether toxins which have been detected in a variety of organisms in many countries. In our present study, accumulation kinetics and toxin distributions in the tissues of seven bivalve species and ascidians relevant to Japanese coastal waters were investigated by experimentally feeding a toxic dinoflagellate Azadinium poporum, which produces azaspiracid-2 (AZA2) as the dominant toxin component. All bivalve species and ascidians investigated in this study had the capability to accumulate AZA2 and no metabolites of AZA2 were detected in the bivalves and the ascidians. Japanese short-neck clams, Japanese oysters, Pacific oysters and ascidians accumulated AZA2 with the highest concentrations on the hepatopancreas, whereas the highest concentrations of AZA2 were found on the gills in surf clams and horse clams. Hard clams and cockles accumulated high levels of AZA2 in both the hepatopancreas and the gills. As far as we know, this is the first report describing detailed tissue distribution of AZAs in several bivalve species other than mussels ( M. edulis ) and scallops ( P. maximus ). Variation of accumulation rates of AZA2 in Japanese short-neck clams on different cell densities or temperatures were observed. Graphical abstract: Image 1 Highlights: Seven bivalve species and ascidians accumulated azaspiracid-2 by experimentally feeding with a toxic dinoflagellate. Azaspiracid-2 was exclusively detected in the bivalves and the ascidians and no metabolites were detected. Japanese short-neck clams, Japanese oysters, Pacific oysters and ascidians showed the highest azaspiracid-2 concentrations on the hepatopancreas. The highest concentrations of azaspiracid-2 were found on the gills in surf clams and horse clams. Hard clams and cockles accumulated high levels of azaspiracid-2 in both the hepatopancreas and the gills.