Sympatric occurrence of two Azadinium poporum ribotypes in the Eastern Mediterranean Sea

Abstract

The marine dinoflagellate Azadinium poporum produce azaspiracids (AZA) and has been recorded widely in the world. However, information on its biogeography is still limited, especially in view of the fact that A. poporum comprises several genetically differentiated groups. A total of 18 strains of A. poporum were obtained from the Eastern Mediterranean area by incubating surface sediment collected from Ionian Sea of Greece. The morphology of these strains was examined with light microscopy and scanning electron microscopy. Small subunit ribosomal DNA (SSU rDNA), large subunit ribosomal DNA (LSU rDNA) and internal transcribed spacer (ITS) sequences were obtained from all cultured strains. Molecular phylogeny based on concatenated SSU, LSU and ITS sequences confirmed three ribotypes within A. poporum and revealed two subclades within ribotypes A and C. Greek strains of A. poporum ribotype A were nested within ribotype A2 together with strains from Western Mediterranean Sea and French Atlantic, and Greek strains of A. poporum ribotype C were nested within ribotype C2 together with a strain from the Gulf of Mexico. Growth experiments on four selected strains revealed that ribotypes A and C from Greece differed in their growth at higher temperatures, indicating that they are physiologically differentiated. Azaspiracid profiles were analyzed for 15 cultured A. poporum strains using LCMS/MS and demonstrate that the A. poporum ribotype A from Greece produce low level or no AZA and A. poporum ribotype C from Greece produces predominantly AZA-40 (9.6-30.2 fg cell) followed by AZA-2 (2.1-2.6 fg cell). The first record of AZA-40 producing A. poporum from the Mediterranean suggests that this species is a potential source for azaspiracid contaminations in shellfish from the Eastern Mediterranean Sea.

Toxigenic strains of Azadinium poporum (Amphidomataceae, Dinophyceae) from Japan and Vietnam, with first reports of A. poporum (ribotype A) and A. trinitatum in Asian Pacific

“…In this study, intraspecific ribotypes of A. poporum were assigned according to Luo et al . (2018). Among them, five cultures from Japan (TOY120, TOY121, MoAz592, MoAz593, MoAz594) having identical sequences, and one culture from Japan (LAM125), were positioned in the ribotype A (not monophyletic in our analysis).…”

Effects of Temperature, Growth Media, and Photoperiod on Growth and Toxin Production of Azadinium spinosum

“…Similar to AZA34, -35, -64, and their phosphorylated conjugates, these compounds were only detected after reaching the stationary phase (Figure 2 and Figure S8). AZA11 has been reported in strains of A. poporum isolated from the south China Sea, the southeast Pacific [3], and the Mediterranean [43], and A. spinosum ribotype B strains collected off the Norwegian coast [14]. The detection of AZA7, an AZA7 isomer, and AZA11 isomer, is the first reporting of these AZA analogues in cultures of A. spinosum .…”

Two novel azaspiracids from Azadinium poporum, and a comprehensive compilation of azaspiracids produced by Amphidomataceae, (Dinophyceae)

“…poporum from very distant areas such as in Argentine coastal waters (Tillmann et al, 2016), the Gulf of Mexico (Luo et al, 2016), Chinese coastal waters (Krock et al, 2014), and the Mediterranean Sea (Luo et al, 2017). AZA-11 is another example for a widely distributed toxin which has been found both in the Pacific region (Tillmann et al, 2017b) as well as in the North Atlantic (Tillmann et al, 2018), and in the Mediterranean Sea (Luo et al, 2018). Other AZA, such as AZA-40 and AZA-59 were initially thought to be local phenomena, i.e.…”

“…Other AZA, such as AZA-40 and AZA-59 were initially thought to be local phenomena, i.e. AZA-40 from the China Sea (Krock et al, 2014), and AZA-59 from coastal water of Washington State, USA (Kim et al, 2017), but recent data show that both of these compounds (albeit in very low amounts) also occur in the Eastern Mediterranean Sea (Luo et al, 2018). This clearly shows that 1) a wide geographical distribution may be a common feature for many, if not all AZA congeners and 2) that many unrecognized AZA derivatives pose a risk until inclusion in (targeted) screenings.…”