<i>Azadinium poporum</i> from the Argentine Continental Shelf, Southwestern Atlantic, produces azaspiracid-2 and azaspiracid-2 phosphate

Abstract

The marine dinophycean genus <i>Azadinium</i> has been identified as the primary source of azaspiracids (AZA), a group of lipophilic phycotoxins known to accumulate in shellfish. Blooms of <i>Azadinium</i> in the southern Atlantic off Argentina have been described from the 1990s, but due to a lack of cultures, the diversity of South-Atlantic <i>Azadinium</i> has not yet been fully explored and their toxin production potential is completely unknown. During a spring 2010 research cruise covering the El Rincon (ER) estuarine system (North Patagonian coast, Argentina, Southwestern Atlantic) a search was conducted for the presence of <i>Azadinium</i>. Although neither <i>Azadinium</i> cells nor AZA in field plankton samples were detected, 10 clonal strains of <i>Azadinium poporum</i> were successfuly established by incubation of sediment samples. Argentinean <i>A. poporum</i> were more variable in size and shape than the type description but conformed to it by the presence of multiple pyrenoids with starch sheath, in plate pattern and arrangement, and in the position of the ventral pore located on the left side of the pore plate. In contrast to all previous description of <i>A. poporum</i>, isolates of the Argentinean <i>A. poporum</i> possessed a distinct field of pores on the second antapical plate. Conspecificity of the Argentinean isolates with <i>A. poporum</i> was confirmed by molecular phylogeny of concatenated ITS and LSU rDNA sequences, where all Argentinean isolates together with some Chinese <i>A. poporum</i> strains formed a well-supported ribotype clade within <i>A. poporum</i>. All isolates produced AZA with the same profile, consisting of AZA-2 as the major compound and, to a lesser extent, its phosphated form. This is the first report of a phosphated marine algal toxin. This first confirmation of the presence of AZA producing <i>Azadinium</i> in the Argentinean coastal area underlines the risk of AZA shellfish contamination episodes in the Southwestern Atlantic region.