Biological Effects of the Azaspiracid-Producing Dinoflagellate Azadinium dexteroporum in Mytilus galloprovincialis from the Mediterranean Sea

Abstract

Azaspiracids (AZAs) are marine biotoxins including a variety of analogues. Recently, novel AZAs produced by the Mediterranean dinoflagellate Azadinium dexteroporum were discovered (AZA-54, AZA-55, 3-epi-AZA-7, AZA-56, AZA-57 and AZA-58) and their biological effects have not been investigated yet. This study aimed to identify the biological responses (biomarkers) induced in mussels Mytilus galloprovincialis after the bioaccumulation of AZAs from A. dexteroporum. Organisms were fed with A. dexteroporum for 21 days and subsequently subjected to a recovery period (normal diet) of 21 days. Exposed organisms accumulated AZA-54, 3-epi-AZA-7 and AZA-55, predominantly in the digestive gland. Mussels’ haemocytes showed inhibition of phagocytosis activity, modulation of the composition of haemocytic subpopulation and damage to lysosomal membranes; the digestive tissue displayed thinned tubule walls, consumption of storage lipids and accumulation of lipofuscin. Slight genotoxic damage was also observed. No clear occurrence of oxidative stress and alteration of nervous activity was detected in AZA-accumulating mussels. Most of the altered parameters returned to control levels after the recovery phase. The toxic effects detected in M. galloprovincialis demonstrate a clear biological impact of the AZAs produced by A. dexteroporum, and could be used as early indicators of contamination associated with the ingestion of seafood.

Cyclic Imines (CIs) in Mussels from North-Central Adriatic Sea: First Evidence of Gymnodimine A in Italy

“…Assuming a mussel composition of 20% by weight for the DG and 80% for the RF, roughly 40% of the toxins ingested by the mussel was found in the DG (Table S3). The preferential accumulation in the DG of the contaminated shellfish was also already reported for other marine biotoxins [73][74][75][76]. Moreover, our data agree with the results obtained by Medhioub et al during the distribution studies conducted on C. gigas exposed to A. ostenfeldii [69].…”

Tetrodotoxins (TTXs) and Vibrio alginolyticus in Mussels from Central Adriatic Sea (Italy): Are They Closely Related?

“…Preferential accumulation in DG has been previously reported for other marine biotoxins in mollusks [44,45].…”

Current Trends and New Challenges in Marine Phycotoxins

“…Marine animals are the main sources of AZA contamination, but only a few studies were performed in vivo with Azadinium revealing a negative effect on feeding behavior of mussels [ 228 ]. The toxic effects detected in mussels could be used as early indicators of contamination associated with the ingestion of seafood [ 229 ]. Additionally, a potential adverse outcome of AZAs in fish development was suggested, with consequent ecological impacts [ 230 ].…”