Dissolved azaspiracids are absorbed and metabolized by blue mussels (Mytilus edulis)

Abstract

The relationship between azaspiracid shellfish poisoning and a small dinoflagellate, Azadinium spinosum, has been shown recently. The organism produces AZA1 and -2, while AZA3 and other analogues are metabolic products formed in shellfish. We evaluated whether mussels were capable of accumulating dissolved AZA1 and -2, and compared the toxin profiles of these mussels at 24 h with profiles of those exposed to live or lysed A. spinosum. We also assessed the possibility of preparative production of AZA metabolites by exposing mussels to semipurified AZA1. We exposed mussels to similar concentration of AZAs: dissolved AZA1+2 (crude extract) at . Subsequently, we dissected and analysed digestive glands, gills and remaining flesh. Mussels (whole flesh) accumulated AZAs above the regulatory limit except at the lower levels of dissolved AZAs.The toxin profile of the mussels varied significantly with treatment. The gills contained 42-46%and the digestive glands 23-24% of the total toxin load using dissolved AZAs, compared to 3-12% and 75-90%, respectively, in mussels exposed to live A. spinosum. Exposure of mussels to semi-purified AZA1 produced the metabolites AZA17 (16.5%) and AZA3 (1.7%) after 4 days of exposure, but the conversion efficiency was too low to justify using this procedure for preparative isolation.

Evidence of the bioaccumulation of ciguatoxins in giant clams (Tridacna maxima) exposed to Gambierdiscus spp. cells

“…In the present study, CTXs were not dissolved directly in the seawater but administered in the form of a cell lysate containing cellular debris. The fact that similar toxin levels were observed in giant clams exposed to either intact or lyzed cells is consistent with the hypothesis of Jauffrais et al (2013) and suggests a digestive uptake route. Since the CBA-N2a analyses were not performed on separate tissues but on the whole animal body, a concomitant uptake of dissolved CTXs through the ctenidia of giant clams cannot, however, be ruled out.…”

“…Interestingly, previous contamination studies of Mytilus edulis with Azadinium spinosum, a known producer of azaspiracids (AZAs), have led to similar findings with the accumulation of AZAs in blue mussels both from lyzed and live Azadinium cells, but also from toxins dissolved directly in the seawater (Jauffrais et al, 2012(Jauffrais et al, , 2013. These authors speculated that partial adsorption of dissolved AZAs onto cellular debris (lyzed cells) or non-toxic cells, followed by their ingestion by the mussels, may favor toxin accumulation in M. edulis digestive gland, whereas dissolved AZAs alone were preferentially found in gills.…”

“…were formally identified in comparison with standards whereas P-CTX-4A, P-CTX-4B, M-seco-P-CTX-4A and two analogs of P-CTX-3C/3B were tentatively identified based on MRM transitions described in Table 1. equiv. L À1 for Ostreopsis (Rhodes et al, 2002), and 0.75-7.5 mg AZAs L À1 for Azadinium (Jauffrais et al, 2012(Jauffrais et al, , 2013. The only difference lies in the fact that giant clams are organisms much bigger in size than the species tested in these previous studies.…”

“…Numerous contamination studies using various toxic dinoflagellates (Alexandrium, Ostreopsis, Azadinium) have been previously conducted on a variety of bivalve molluscs such as mussels, scallops, oysters, and clams (Rhodes et al, 2002;Rolland et al, 2012;Jauffrais et al, 2012Jauffrais et al, , 2013Haberkorn et al, 2014). Although animals were consistently exposed to higher concentrations of toxic cells in these experiments, ranging from 1 Â 10 3 to 1 Â 10 5 cells mL À1 , the total toxin loads supplied to target animals were estimated to be of the same order of magnitude as in the present study: i.e.…”

Gambierol: Synthetic Aspects

“…above regulatory limits 77 . Interestingly, the toxin distribution in the mussel tissue was different: when fed A. spinosum, mussels mainly accumulated AZAs in digestive glands, but mussels exposed to dissolved AZAs accumulated a significant proportion of toxins in the gills.…”