HIGH AMOUNT OF DINOPHYSISTOXIN-3 IN Mytilus chilensis COLLECTED IN SENO DE RELONCAVI, CHILE, DURING MASSIVE HUMAN INTOXICATION ASSOCIATED WITH OUTBREAK OF Vibrio parahaemolyticus

Transcriptomic Profile of the Cockle Cerastoderma edule Exposed to Seasonal Diarrhetic Shellfish Toxin Contamination

Bivalves constitute an important source of proteins for human consumption, but some accumulate biotoxins such as diarrhetic shellfish toxins (DSTs), constituting a risk to human health. The cockle Cerastoderma edule is one of the most important species harvested in the Portuguese coast but also one of the most affected species due to recurrent DSTs exposure. However, little is known regarding the effects of the toxins produced by blooming dinoflagellates on C. edule. Herein, we explore the Differentially Expressed Genes (DEGs) of two tissues (gills and digestive gland) from wild cockles sampled in Portugal, through their whole transcriptomic response in two different seasons (exposed and not exposed to DSTs). The de novo transcriptome assembly returned 684,723 contigs, N50 of 1049, and 98.53% completeness. Altogether, 1098 DEGs were identified, of which 353 DEGs were exclusive for the digestive gland, 536 unique for the gills and 209 DEGs were common. Among DEGs were identified known DSTs-biomarkers including glutathione peroxidase, glutathione S-transferase, superoxide dismutase, cytochrome P450, ABC transporters, actin and tubulin-related proteins, Heat shock proteins and complement C1Q-like proteins. This study provides the first transcriptomic profile of C. edule, giving new insights about its molecular responses under different environmental conditions of DSTs exposure.

The Latin America and Caribbean HAB status report based on OBIS and HAEDAT maps and databases

Harmful Algae Blooms (HAB) have been documented for at least fifty years in Latin America and the Caribbean (LAC), however, their impacts at social, ecological and economic levels are still little known. To contribute to the impact assessment of HABs in LAC region, the available information in HAEDAT, OBIS, CAREC, and CARPHA databases, and scientific literature was analyzed. This historical analysis allows identification of the main syndromes and causal organisms. Considering the existence of two regional working groups of the Intergovernmental Oceanographic Commission (IOC): Algas Nocivas del Caribe (ANCA) and Floraciones Algales Nocivas en Sudamérica (FANSA), representing Central American/Caribbean and South American countries, respectively, the analysis is presented both globally and subregional. For the FANSA region, the HAEDAT data base listed 249 records from 1970 to 2019, with a total of 1432 human intoxications, including 37 fatalities. The majority of these events comprised Paralytic Shellfish Toxins (49%), Diarrhetic Shellfish Toxins (34%), Cyanotoxins (12%) and 6 % other toxins. The total number of harmful taxa in the OBIS database includes 79 species distributed over 25 genera. The most commonly reported species are Alexandrium catenella/tamarense, Gymnodinium catenatum and the Dinophysis acuminata complex. Two new species Prorocentrum caipirignum Fraga, Menezes and Nascimento and Alexandrium fragae Branco and Menezes were newly described from Brazilian waters. In the ANCA region, HAEDAT listed 131 records from 1956 to 2018. The main problems are PSP and Ciguatera and common HAB taxa are Gambierdiscus, Gymnodinium, Pyrodinium, Alexandrium and Dinophysis. The most reported HAB forming species are Gymnodinium catenatum, Pyrodinium bahamense and Gambierdiscus spp. In recent years Margalefidinium polykrikoides blooms have become frequent, causing fish and invertebrates massive mortalities and impacts on touristic activities. In the LAC region, the greatest economic losses were produced by ichthyotoxic massive events causing salmon deaths associated to Pseudochattonella verruculosa and Alexandrium catenella in Chile and tuna deaths related to Tripos furca and Chattonella spp. in the Mexican Pacific. In the last decade, several studies in LAC have linked HAB events with local mesoscale oceanographic and atmospheric phenomena. Trends analyzed up to 2019 are related to the increasing awareness about presence of toxic species, the geographical expansion of already known species, the detection of new toxins for the region, and HAB events duration and/or impacts.

Shellfish contamination with marine biotoxins in Portugal and spring tides: a dangerous health coincidence

Bivalve molluscs can acquire marine biotoxins by filter-feeding upon certain toxin-producing microalgae. The two most common syndromes observed in temperate coastal waters have been diarrhetic shellfish poisoning (DSP) and paralytic shellfish poisoning (PSP). While DSP is a non-fatal gastrointestinal syndrome, PSP is a neurological syndrome which can lead to death by respiratory paralysis in high intoxication scenarios. In Portugal, the presence of both DSP and PSP toxins leads to recurrent seasonal bans of bivalve harvesting. On a few occasions, the bans were not placed in time, not properly disseminated to the public or were disregarded by recreational harvesters. Several cases of poisonings have been studied in collaboration between health authorities and the laboratory in charge of the biotoxin monitoring programme. Some of the outbreaks have even called the attention of the local media. In several of these recorded cases, a common trait has emerged throughout the years: bivalve harvest had often been done during very low tides attributed to either new or full moons. These tides expose intertidal bivalves more widely, increase harvesting time, and allow picking of larger-sized specimens. In some occasions, the consumers were extremely unfortunate because a noxious coincidence had occurred: larger-sized specimens were available but had attained the highest toxin content of the toxic season. This review alerts that despite costly monitoring programmes have been perfected through the years, human poisonings still take place due to the rapid increase in toxin levels and/or disrespect of harvest bans.

Variability and profiles of lipophilic toxins in bivalves from Great Britain during five and a half years of monitoring: Okadaic acid, dinophysis toxins and pectenotoxins

Official control biotoxin testing of bivalve molluscs from Great Britain has been conducted by Cefas for over a decade. Reflecting the changes in legislation, bioassays were gradually replaced by analytical methods, firstly for analysis of Paralytic shellfish toxins, followed by introduction of liquid chromatography tandem mass spectrometric (LCMS/MS) method for lipophilic toxins (LTs) in 2011. Twelve compounds, representing three main groups of regulated lipophilic toxins, as well as two non-regulated cyclic imines were examined in over 20,500 samples collected between July 2011 and December 2016. The toxins belonging to Okadaic acid (OA) group toxins were the most prevalent and were quantified in 23% of samples, predominantly from Scotland. The temporal pattern of OA group occurrences remained similar each year, peaking in summer months and tailing off during autumn and winter, however their abundance and magnitude varied between years significantly, with concentrations reaching up to 4993 μg OA eq./kg. Three toxin profiles were identified, reflecting the relative contribution of the two main toxins, OA and dinophysis toxin-2 (DTX2). Dinophysis toxin-1 (DTX1) was less common and was never detected in samples with high proportions of DTX2. Inter-annual changes in profiles were observed within certain regions, with the most notable being an increase of DTX2 occurrences in north-west Scotland and England in the last three years of monitoring. In addition, seasonal changes of profiles were identified when OA, the dominant toxin in early summer, was replaced by higher proportions of DTX2 in late summer and autumn. The profile distribution possibly reflected the availability of individual Dinophysis species as a food source for shellfish, however persistence of DTX2 during autumn and winter in mussels might have also been attributed to their physiology. Mussels were the only species with higher average proportions of non-esterified toxins, while Pacific oysters, cockles, surf clams, razors and queen scallops contained almost exclusively ester forms. In addition, a temporal change in proportion of OA and DTX2 free form was observed in mussels. Pectenotoxin-2 (PTX2) was quantified only on rare occasions.

Esterification of okadaic acid in the mussel Mytilus galloprovincialis

Okadaic acid and other toxins of the diarrheic shellfish poisoning (DSP) group are transformed mainly to their acyl-derivatives in bivalves. Some recent studies suggest that bacteria present in the bivalve gut could contribute substantially to the acylation of the toxins. By feeding microcapsules containing okadaic acid to mussels we have shown unequivocally that the ingested okadaic acid is nearly completely transformed to its fatty acid esters (acyl-derivatives). Treating mussels with antibiotics did not have any significant effect on the acylation of the supplied okadaic acid, suggesting that bacteria do not play any significant role in this process. The microsomal and mitochondrial subcellular fractions of the cells of the digestive gland have been shown to have contain enzymes that are able to transfer a fatty acid molecule from Coenzyme A to okadaic acid (so, that have Acyl-CoA:OA acyltransferase activity). This activity was related to that of the enzyme Cytochrome C reductase (NADPH), a marker of endoplasmic reticulum, suggesting that this organelle is the main responsible for the acylation process. Acylation of DSP toxins seems to be a key step in the depuration of these toxins from mussels, as these compounds are found in feces as acyl-derivatives. This is probably true for most bivalves. The proportion of acyl-derivatives accumulated can point to the key process of the depuration: acylation or excretion of acylated derivatives. In the mussels Mytilus galloprovincialis, Mytilus edulis and in Donax trunculus, the first process seems to be the most important, but in most bivalve species it seems to be the second one. Other aspects of the relationship between depuration and acylation are also discussed.

First evidence of Okadaic acid acyl-derivative and Dinophysistoxin-3 in mussel samples collected in Chiloe Island, Southern Chile

This paper shows the detection of Diarrhetic Shellfish Poison (DSP) phycotoxins, using HPLC-FLD with pre-column derivatization procedure and HPLC-MS methods, in the analysis of shellfish extracts tested positive with the official DSP mouse bioassay. The shellfish samples were collected in Chiloe Island, Southern of Chile. The amount of Dinophysistoxin-3 (DTX-3) measured in the shellfish extracts were in average above the international safe limits for DSP content in the shellfish extracts analyzed. As internal control of detection and recovery, DTX-1 analytical standard was spiked into dichloromethane-clean shellfish extracts in order to calculate de extraction recovery of DTX-1. The average recovery was 97%. From all DSP toxins analyzed, the hydrolyzed extract samples appeared mainly DTX-3 in concentrations ranging from 99.40 +/- 1.22 to 257.73 +/- 12.46 ng/g digestive-glands. The acyl-Okadaic Acid (acyl-OA) was also detected in some samples, ranging from 1.02 +/- 1.4 to 3.07. +/- 1.6 ng of DSP toxin/g digestive-glands. This is the first report of acyl-OA ever found in Chilean shellfish samples. This data shows that shellfish samples were contaminated with a complex DSP toxins profile, in which DTX-3 is the major DSP toxin component, followed by DTX-1 and the acyl-OA as the minor one. The important findings showed in this study are the presence of both acyl-derivates (DTX-3 and Acyl-OA) which are the product of a main metabolic biotransformation that occurred inside the shellfish, in order to chelate DTX-1 and OA, transforming them into DTX-3 and the acyl-OA respectively. This metabolic biotransformation must be performed to avoid self-inhibition of their Protein Phosphatase 2A done by DTX-1 and OA, since both acyl-derivates (DTX-3 and acyl-OA) do not inhibit Protein Phosphatase 2A. This complex DSP toxins profile and the permanent presence of both acyl-derivates (DTX-3 and Acyl-OA) could explain the permanent diarrhea symptoms that experience patients who have ingested cooked shellfish in the southern of Chile. This diarrhea is not associated to Vibrio parahaemolyticus or other enteropathogens as had been suggested before. The massive shellfish consumption is an important Chilean cultural habit and now has become a major health issue in the southern of Chile.

First identification of azaspiracid and spirolides in Mesodesma donacium and Mulinia edulis from Northern Chile

In an attempt to evaluate the risk for human consumption associated to the accumulation of lipophilic toxins by two commercially important bivalves: macha (Mesodesma donacium) and clam (Mulinia edulis) in Coquimbo Bay (Chile), monitoring of these species was carried out from March to September 2008. The samples were analyzed by liquid chromatography-mass spectrometry (LC-MS) to detect okadaic acid, dinophysistoxins, pectenotoxins, azaspiracids, yessotoxins and spirolides. Low levels of Azaspiracid-1 and 13-desmethyl C spirolide were found in both species. The toxins were detected at different dates throughout the monitoring period and in some cases both toxins were detected in the same sample. In all cases, the concentration of the toxins was below the limit of quantification of the technique used and therefore these detections are only indicative of a potential risk. This is the first report of the occurrence of these groups of toxins in Chile and suggests that it is necessary to monitor routinely these substances to warrant public health and shellfish exportations.